* [PATCH] Set the retain attribute on _elf_set_element if CC supports [BZ #27492]
@ 2021-03-15 1:10 Fangrui Song
2021-03-15 7:28 ` Florian Weimer
0 siblings, 1 reply; 40+ messages in thread
From: Fangrui Song @ 2021-03-15 1:10 UTC (permalink / raw)
To: libc-alpha; +Cc: Fangrui Song
So that text_set_element/data_set_element/bss_set_element defined
variables will be retained by the linker.
Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable
will not be optimized out; 'retain' prevents section garbage collection
if the linker support SHF_GNU_RETAIN.
GNU ld 2.36 and LLD 13 support -z start-stop-gc which allow C identifier
name sections to be GCed even if there are live __start_/__stop_
references.
Without the change, there are some static linking problems, e.g.
_IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so
stdout is not flushed on exit.
Note: `#if defined (__has_attribute) && __has_attribute (retain)`
does not work in GCC assembly mode:
error: missing binary operator before token "("
---
include/libc-symbols.h | 24 ++++++++++++++++++++----
1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/include/libc-symbols.h b/include/libc-symbols.h
index c83e550b03..291a8d8f08 100644
--- a/include/libc-symbols.h
+++ b/include/libc-symbols.h
@@ -373,16 +373,32 @@ for linking")
/* These are all done the same way in ELF.
There is a new section created for each set. */
-#ifdef SHARED
+#ifdef __has_attribute
+#if __has_attribute (retain)
+# ifdef SHARED
/* When building a shared library, make the set section writable,
because it will need to be relocated at run time anyway. */
-# define _elf_set_element(set, symbol) \
+# define _elf_set_element(set, symbol) \
static const void *__elf_set_##set##_element_##symbol##__ \
- __attribute__ ((used, section (#set))) = &(symbol)
+ __attribute__ ((used, retain, section (#set))) = &(symbol)
+# else
+# define _elf_set_element(set, symbol) \
+ static const void *const __elf_set_##set##_element_##symbol##__ \
+ __attribute__ ((used, retain, section (#set))) = &(symbol)
+# endif
#else
-# define _elf_set_element(set, symbol) \
+# ifdef SHARED
+/* When building a shared library, make the set section writable,
+ because it will need to be relocated at run time anyway. */
+# define _elf_set_element(set, symbol) \
+ static const void *__elf_set_##set##_element_##symbol##__ \
+ __attribute__ ((used, section (#set))) = &(symbol)
+# else
+# define _elf_set_element(set, symbol) \
static const void *const __elf_set_##set##_element_##symbol##__ \
__attribute__ ((used, section (#set))) = &(symbol)
+# endif
+#endif
#endif
/* Define SET as a symbol set. This may be required (it is in a.out) to
--
2.31.0.rc2.261.g7f71774620-goog
^ permalink raw reply [flat|nested] 40+ messages in thread* Re: [PATCH] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-15 1:10 [PATCH] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] Fangrui Song @ 2021-03-15 7:28 ` Florian Weimer 2021-03-15 7:45 ` Fāng-ruì Sòng 0 siblings, 1 reply; 40+ messages in thread From: Florian Weimer @ 2021-03-15 7:28 UTC (permalink / raw) To: Fangrui Song via Libc-alpha; +Cc: Fangrui Song * Fangrui Song via Libc-alpha: > So that text_set_element/data_set_element/bss_set_element defined > variables will be retained by the linker. > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > will not be optimized out; 'retain' prevents section garbage collection > if the linker support SHF_GNU_RETAIN. This needs recent-ish GCC 11, see commit 6347f4a0904fce17e ("Add retain attribute to place symbols in SHF_GNU_RETAIN section). > +#ifdef __has_attribute > +#if __has_attribute (retain) > +# ifdef SHARED Indentation is off there. It's probably simpler to define a new macro, like ELEMENT_SECTION_ATTRIBUTES, and use that unconditionally, perhaps like this? #ifndef __ASSEMBLER__ # if defined (__has_attribute) && __has_attribute (retain) # define ELEMENT_SECTION_ATTRIBUTES used, retain # else # define ELEMENT_SECTION_ATTRIBUTES used # endif #endif Have you checked that __has_attribute (retain) is only true on GCC if the underlying linker has retain support and the attribute does not produce a warning? Thanks, Florian ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-15 7:28 ` Florian Weimer @ 2021-03-15 7:45 ` Fāng-ruì Sòng 2021-03-15 8:13 ` Florian Weimer 0 siblings, 1 reply; 40+ messages in thread From: Fāng-ruì Sòng @ 2021-03-15 7:45 UTC (permalink / raw) To: Florian Weimer; +Cc: Fangrui Song via Libc-alpha On Mon, Mar 15, 2021 at 12:28 AM Florian Weimer <fweimer@redhat.com> wrote: > > * Fangrui Song via Libc-alpha: > > > So that text_set_element/data_set_element/bss_set_element defined > > variables will be retained by the linker. > > > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > > will not be optimized out; 'retain' prevents section garbage collection > > if the linker support SHF_GNU_RETAIN. > > This needs recent-ish GCC 11, see commit 6347f4a0904fce17e ("Add retain > attribute to place symbols in SHF_GNU_RETAIN section). > > > +#ifdef __has_attribute > > +#if __has_attribute (retain) > > +# ifdef SHARED > > Indentation is off there. OK. I can increase the level of indentation... > It's probably simpler to define a new macro, like > ELEMENT_SECTION_ATTRIBUTES, and use that unconditionally, perhaps like > this? > > #ifndef __ASSEMBLER__ > # if defined (__has_attribute) && __has_attribute (retain) > # define ELEMENT_SECTION_ATTRIBUTES used, retain > # else > # define ELEMENT_SECTION_ATTRIBUTES used > # endif > #endif `#ifdef __has_attribute` should be fine without #ifndef __ASSEMBLER__ ? > Have you checked that __has_attribute (retain) is only true on GCC if > the underlying linker has retain support and the attribute does not > produce a warning? There is a GCC bug. I've reported https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587 > > Thanks, > Florian > ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-15 7:45 ` Fāng-ruì Sòng @ 2021-03-15 8:13 ` Florian Weimer 2021-03-22 4:00 ` [PATCH v2] " Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: Florian Weimer @ 2021-03-15 8:13 UTC (permalink / raw) To: Fāng-ruì Sòng; +Cc: Fangrui Song via Libc-alpha * Fāng-ruì Sòng: >> It's probably simpler to define a new macro, like >> ELEMENT_SECTION_ATTRIBUTES, and use that unconditionally, perhaps like >> this? >> >> #ifndef __ASSEMBLER__ >> # if defined (__has_attribute) && __has_attribute (retain) >> # define ELEMENT_SECTION_ATTRIBUTES used, retain >> # else >> # define ELEMENT_SECTION_ATTRIBUTES used >> # endif >> #endif > > `#ifdef __has_attribute` should be fine without #ifndef __ASSEMBLER__ ? ELEMENT_SECTION_ATTRIBUTES is not useful to the assembler, and checking for __ASSEMBLER__ on the outer level makes it simpler to define the no-retain case. >> Have you checked that __has_attribute (retain) is only true on GCC if >> the underlying linker has retain support and the attribute does not >> produce a warning? > > There is a GCC bug. I've reported > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587 If this isn't fixed in GCC, we'll need a configure check because we want to keep building with -Werror=attributes. Thank,s Florian ^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v2] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-15 8:13 ` Florian Weimer @ 2021-03-22 4:00 ` Fangrui Song 2021-03-22 4:24 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-03-22 4:00 UTC (permalink / raw) To: libc-alpha, Florian Weimer; +Cc: Fangrui Song So that text_set_element/data_set_element/bss_set_element defined variables will be retained by the linker. Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable will not be optimized out; 'retain' prevents section garbage collection if the linker support SHF_GNU_RETAIN. GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C identifier name sections to be GCed even if there are live __start_/__stop_ references. Without the change, there are some static linking problems, e.g. _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so stdout is not flushed on exit. Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). --- config.h.in | 3 +++ configure | 23 +++++++++++++++++++++++ configure.ac | 16 ++++++++++++++++ include/libc-symbols.h | 30 +++++++++++++++++++++--------- 4 files changed, 63 insertions(+), 9 deletions(-) diff --git a/config.h.in b/config.h.in index f21bf04e47..cc875e90f9 100644 --- a/config.h.in +++ b/config.h.in @@ -187,6 +187,9 @@ /* Define if gcc supports attribute ifunc. */ #undef HAVE_GCC_IFUNC +/* Define if gcc supports attribute retain. */ +#undef HAVE_GCC_RETAIN + /* Define if the linker defines __ehdr_start. */ #undef HAVE_EHDR_START diff --git a/configure b/configure index 37cef37413..28494de748 100755 --- a/configure +++ b/configure @@ -4105,6 +4105,29 @@ fi $as_echo "$libc_cv_textrel_ifunc" >&6; } +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 +$as_echo_n "checking for gcc attribute retain support... " >&6; } +if ${libc_cv_gcc_retain+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gcc_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ + 2>&5 ; then + libc_cv_gcc_retain=yes +fi +rm -f conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 +$as_echo "$libc_cv_gcc_retain" >&6; } +if test $libc_cv_gcc_retain = yes; then + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h + +fi + # Check if gcc warns about alias for function with incompatible types. { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } diff --git a/configure.ac b/configure.ac index 16b15b6f90..94ad713820 100644 --- a/configure.ac +++ b/configure.ac @@ -707,6 +707,22 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_textrel_ifunc) +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. +AC_CACHE_CHECK([for gcc attribute retain support], + libc_cv_gcc_retain, [dnl +cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gcc_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ + 2>&AS_MESSAGE_LOG_FD ; then + libc_cv_gcc_retain=yes +fi +rm -f conftest*]) +if test $libc_cv_gcc_retain = yes; then + AC_DEFINE(HAVE_GCC_RETAIN) +fi + # Check if gcc warns about alias for function with incompatible types. AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], libc_cv_gcc_incompatible_alias, [dnl diff --git a/include/libc-symbols.h b/include/libc-symbols.h index c83e550b03..f8eafcf1f3 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -373,17 +373,29 @@ for linking") /* These are all done the same way in ELF. There is a new section created for each set. */ -#ifdef SHARED +#ifdef HAVE_GCC_RETAIN +# ifdef SHARED /* When building a shared library, make the set section writable, - because it will need to be relocated at run time anyway. */ -# define _elf_set_element(set, symbol) \ - static const void *__elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + because it will need to be relocated at run time anyway. */ +# define _elf_set_element(set, symbol) \ + static const void *__elf_set_##set##_element_##symbol##__ \ + __attribute__ ((used, retain, section (#set))) = &(symbol) +# else +# define _elf_set_element(set, symbol) \ + static const void *const __elf_set_##set##_element_##symbol##__ \ + __attribute__ ((used, retain, section (#set))) = &(symbol) +# endif #else -# define _elf_set_element(set, symbol) \ - static const void *const __elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) -#endif +# ifdef SHARED +# define _elf_set_element(set, symbol) \ + static const void *__elf_set_##set##_element_##symbol##__ \ + __attribute__ ((used, section (#set))) = &(symbol) +# else +# define _elf_set_element(set, symbol) \ + static const void *const __elf_set_##set##_element_##symbol##__ \ + __attribute__ ((used, section (#set))) = &(symbol) +# endif +#endif /* HAVE_GCC_RETAIN */ /* Define SET as a symbol set. This may be required (it is in a.out) to be able to use the set's contents. */ -- 2.31.0.rc2.261.g7f71774620-goog ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v2] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-22 4:00 ` [PATCH v2] " Fangrui Song @ 2021-03-22 4:24 ` H.J. Lu 2021-03-22 4:40 ` Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-03-22 4:24 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Sun, Mar 21, 2021 at 9:01 PM Fangrui Song via Libc-alpha <libc-alpha@sourceware.org> wrote: > > So that text_set_element/data_set_element/bss_set_element defined > variables will be retained by the linker. > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > will not be optimized out; 'retain' prevents section garbage collection > if the linker support SHF_GNU_RETAIN. > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > identifier name sections to be GCed even if there are live > __start_/__stop_ references. > > Without the change, there are some static linking problems, e.g. > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > stdout is not flushed on exit. > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > --- > config.h.in | 3 +++ > configure | 23 +++++++++++++++++++++++ > configure.ac | 16 ++++++++++++++++ > include/libc-symbols.h | 30 +++++++++++++++++++++--------- > 4 files changed, 63 insertions(+), 9 deletions(-) > > diff --git a/config.h.in b/config.h.in > index f21bf04e47..cc875e90f9 100644 > --- a/config.h.in > +++ b/config.h.in > @@ -187,6 +187,9 @@ > /* Define if gcc supports attribute ifunc. */ > #undef HAVE_GCC_IFUNC > > +/* Define if gcc supports attribute retain. */ > +#undef HAVE_GCC_RETAIN > + > /* Define if the linker defines __ehdr_start. */ > #undef HAVE_EHDR_START > > diff --git a/configure b/configure > index 37cef37413..28494de748 100755 > --- a/configure > +++ b/configure > @@ -4105,6 +4105,29 @@ fi > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > +$as_echo_n "checking for gcc attribute retain support... " >&6; } > +if ${libc_cv_gcc_retain+:} false; then : > + $as_echo_n "(cached) " >&6 > +else > + cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gcc_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > + 2>&5 ; then > + libc_cv_gcc_retain=yes > +fi > +rm -f conftest* > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > +$as_echo "$libc_cv_gcc_retain" >&6; } > +if test $libc_cv_gcc_retain = yes; then > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > + > +fi > + > # Check if gcc warns about alias for function with incompatible types. > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > diff --git a/configure.ac b/configure.ac > index 16b15b6f90..94ad713820 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -707,6 +707,22 @@ fi > rm -f conftest*]) > AC_SUBST(libc_cv_textrel_ifunc) > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > +AC_CACHE_CHECK([for gcc attribute retain support], > + libc_cv_gcc_retain, [dnl > +cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gcc_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > + 2>&AS_MESSAGE_LOG_FD ; then > + libc_cv_gcc_retain=yes > +fi > +rm -f conftest*]) > +if test $libc_cv_gcc_retain = yes; then > + AC_DEFINE(HAVE_GCC_RETAIN) > +fi > + > # Check if gcc warns about alias for function with incompatible types. > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > libc_cv_gcc_incompatible_alias, [dnl > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > index c83e550b03..f8eafcf1f3 100644 > --- a/include/libc-symbols.h > +++ b/include/libc-symbols.h > @@ -373,17 +373,29 @@ for linking") > > /* These are all done the same way in ELF. > There is a new section created for each set. */ > -#ifdef SHARED > +#ifdef HAVE_GCC_RETAIN > +# ifdef SHARED > /* When building a shared library, make the set section writable, > - because it will need to be relocated at run time anyway. */ > -# define _elf_set_element(set, symbol) \ > - static const void *__elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) You should define __attribute_used_and_retain__ instead. > + because it will need to be relocated at run time anyway. */ > +# define _elf_set_element(set, symbol) \ > + static const void *__elf_set_##set##_element_##symbol##__ \ > + __attribute__ ((used, retain, section (#set))) = &(symbol) > +# else > +# define _elf_set_element(set, symbol) \ > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + __attribute__ ((used, retain, section (#set))) = &(symbol) > +# endif > #else > -# define _elf_set_element(set, symbol) \ > - static const void *const __elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > -#endif > +# ifdef SHARED > +# define _elf_set_element(set, symbol) \ > + static const void *__elf_set_##set##_element_##symbol##__ \ > + __attribute__ ((used, section (#set))) = &(symbol) > +# else > +# define _elf_set_element(set, symbol) \ > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + __attribute__ ((used, section (#set))) = &(symbol) > +# endif > +#endif /* HAVE_GCC_RETAIN */ > > /* Define SET as a symbol set. This may be required (it is in a.out) to > be able to use the set's contents. */ > -- > 2.31.0.rc2.261.g7f71774620-goog > libc.a is an installed file. Does this work with older linkers? -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v2] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-22 4:24 ` H.J. Lu @ 2021-03-22 4:40 ` Fangrui Song 2021-03-22 20:28 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-03-22 4:40 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-03-21, H.J. Lu wrote: >On Sun, Mar 21, 2021 at 9:01 PM Fangrui Song via Libc-alpha ><libc-alpha@sourceware.org> wrote: >> >> So that text_set_element/data_set_element/bss_set_element defined >> variables will be retained by the linker. >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> will not be optimized out; 'retain' prevents section garbage collection >> if the linker support SHF_GNU_RETAIN. >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> identifier name sections to be GCed even if there are live >> __start_/__stop_ references. >> >> Without the change, there are some static linking problems, e.g. >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> stdout is not flushed on exit. >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> --- >> config.h.in | 3 +++ >> configure | 23 +++++++++++++++++++++++ >> configure.ac | 16 ++++++++++++++++ >> include/libc-symbols.h | 30 +++++++++++++++++++++--------- >> 4 files changed, 63 insertions(+), 9 deletions(-) >> >> diff --git a/config.h.in b/config.h.in >> index f21bf04e47..cc875e90f9 100644 >> --- a/config.h.in >> +++ b/config.h.in >> @@ -187,6 +187,9 @@ >> /* Define if gcc supports attribute ifunc. */ >> #undef HAVE_GCC_IFUNC >> >> +/* Define if gcc supports attribute retain. */ >> +#undef HAVE_GCC_RETAIN >> + >> /* Define if the linker defines __ehdr_start. */ >> #undef HAVE_EHDR_START >> >> diff --git a/configure b/configure >> index 37cef37413..28494de748 100755 >> --- a/configure >> +++ b/configure >> @@ -4105,6 +4105,29 @@ fi >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 >> +$as_echo_n "checking for gcc attribute retain support... " >&6; } >> +if ${libc_cv_gcc_retain+:} false; then : >> + $as_echo_n "(cached) " >&6 >> +else >> + cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gcc_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> + 2>&5 ; then >> + libc_cv_gcc_retain=yes >> +fi >> +rm -f conftest* >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 >> +$as_echo "$libc_cv_gcc_retain" >&6; } >> +if test $libc_cv_gcc_retain = yes; then >> + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h >> + >> +fi >> + >> # Check if gcc warns about alias for function with incompatible types. >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> diff --git a/configure.ac b/configure.ac >> index 16b15b6f90..94ad713820 100644 >> --- a/configure.ac >> +++ b/configure.ac >> @@ -707,6 +707,22 @@ fi >> rm -f conftest*]) >> AC_SUBST(libc_cv_textrel_ifunc) >> >> +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. >> +AC_CACHE_CHECK([for gcc attribute retain support], >> + libc_cv_gcc_retain, [dnl >> +cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gcc_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> + 2>&AS_MESSAGE_LOG_FD ; then >> + libc_cv_gcc_retain=yes >> +fi >> +rm -f conftest*]) >> +if test $libc_cv_gcc_retain = yes; then >> + AC_DEFINE(HAVE_GCC_RETAIN) >> +fi >> + >> # Check if gcc warns about alias for function with incompatible types. >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> libc_cv_gcc_incompatible_alias, [dnl >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> index c83e550b03..f8eafcf1f3 100644 >> --- a/include/libc-symbols.h >> +++ b/include/libc-symbols.h >> @@ -373,17 +373,29 @@ for linking") >> >> /* These are all done the same way in ELF. >> There is a new section created for each set. */ >> -#ifdef SHARED >> +#ifdef HAVE_GCC_RETAIN >> +# ifdef SHARED >> /* When building a shared library, make the set section writable, >> - because it will need to be relocated at run time anyway. */ >> -# define _elf_set_element(set, symbol) \ >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) > >You should define __attribute_used_and_retain__ instead. > >> + because it will need to be relocated at run time anyway. */ >> +# define _elf_set_element(set, symbol) \ >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> + __attribute__ ((used, retain, section (#set))) = &(symbol) >> +# else >> +# define _elf_set_element(set, symbol) \ >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> + __attribute__ ((used, retain, section (#set))) = &(symbol) >> +# endif >> #else >> -# define _elf_set_element(set, symbol) \ >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> -#endif >> +# ifdef SHARED >> +# define _elf_set_element(set, symbol) \ >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> + __attribute__ ((used, section (#set))) = &(symbol) >> +# else >> +# define _elf_set_element(set, symbol) \ >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> + __attribute__ ((used, section (#set))) = &(symbol) >> +# endif >> +#endif /* HAVE_GCC_RETAIN */ >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> be able to use the set's contents. */ >> -- >> 2.31.0.rc2.261.g7f71774620-goog >> > >libc.a is an installed file. Does this work with older linkers? > >-- >H.J. How about /* These are all done the same way in ELF. There is a new section created for each set. */ #ifdef HAVE_GCC_RETAIN # define attribute_used_retain_section(sec) \ __attribute__ ((used, retain, section (sec))) #else # define attribute_used_retain_section(sec) \ __attribute__ ((used, section (sec))) #endif #ifdef SHARED /* When building a shared library, make the set section writable, because it will need to be relocated at run time anyway. */ # define _elf_set_element(set, symbol) \ static const void *__elf_set_##set##_element_##symbol##__ \ attribute_used_retain_section(#set) = &(symbol) #else # define _elf_set_element(set, symbol) \ static const void *const __elf_set_##set##_element_##symbol##__ \ attribute_used_retain_section(#set) = &(symbol) #endif ? Yes, older linkers just ignore unknown section flags. That is the ELF spirit. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v2] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-22 4:40 ` Fangrui Song @ 2021-03-22 20:28 ` H.J. Lu 2021-03-23 4:14 ` Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-03-22 20:28 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Sun, Mar 21, 2021 at 9:40 PM Fangrui Song <maskray@google.com> wrote: > > On 2021-03-21, H.J. Lu wrote: > >On Sun, Mar 21, 2021 at 9:01 PM Fangrui Song via Libc-alpha > ><libc-alpha@sourceware.org> wrote: > >> > >> So that text_set_element/data_set_element/bss_set_element defined > >> variables will be retained by the linker. > >> > >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> will not be optimized out; 'retain' prevents section garbage collection > >> if the linker support SHF_GNU_RETAIN. > >> > >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> identifier name sections to be GCed even if there are live > >> __start_/__stop_ references. > >> > >> Without the change, there are some static linking problems, e.g. > >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> stdout is not flushed on exit. > >> > >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> --- > >> config.h.in | 3 +++ > >> configure | 23 +++++++++++++++++++++++ > >> configure.ac | 16 ++++++++++++++++ > >> include/libc-symbols.h | 30 +++++++++++++++++++++--------- > >> 4 files changed, 63 insertions(+), 9 deletions(-) > >> > >> diff --git a/config.h.in b/config.h.in > >> index f21bf04e47..cc875e90f9 100644 > >> --- a/config.h.in > >> +++ b/config.h.in > >> @@ -187,6 +187,9 @@ > >> /* Define if gcc supports attribute ifunc. */ > >> #undef HAVE_GCC_IFUNC > >> > >> +/* Define if gcc supports attribute retain. */ > >> +#undef HAVE_GCC_RETAIN > >> + > >> /* Define if the linker defines __ehdr_start. */ > >> #undef HAVE_EHDR_START > >> > >> diff --git a/configure b/configure > >> index 37cef37413..28494de748 100755 > >> --- a/configure > >> +++ b/configure > >> @@ -4105,6 +4105,29 @@ fi > >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> > >> > >> +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > >> +$as_echo_n "checking for gcc attribute retain support... " >&6; } > >> +if ${libc_cv_gcc_retain+:} false; then : > >> + $as_echo_n "(cached) " >&6 > >> +else > >> + cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gcc_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> + 2>&5 ; then > >> + libc_cv_gcc_retain=yes > >> +fi > >> +rm -f conftest* > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > >> +$as_echo "$libc_cv_gcc_retain" >&6; } > >> +if test $libc_cv_gcc_retain = yes; then > >> + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > >> + > >> +fi > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> diff --git a/configure.ac b/configure.ac > >> index 16b15b6f90..94ad713820 100644 > >> --- a/configure.ac > >> +++ b/configure.ac > >> @@ -707,6 +707,22 @@ fi > >> rm -f conftest*]) > >> AC_SUBST(libc_cv_textrel_ifunc) > >> > >> +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > >> +AC_CACHE_CHECK([for gcc attribute retain support], > >> + libc_cv_gcc_retain, [dnl > >> +cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gcc_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> + 2>&AS_MESSAGE_LOG_FD ; then > >> + libc_cv_gcc_retain=yes > >> +fi > >> +rm -f conftest*]) > >> +if test $libc_cv_gcc_retain = yes; then > >> + AC_DEFINE(HAVE_GCC_RETAIN) > >> +fi > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> libc_cv_gcc_incompatible_alias, [dnl > >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> index c83e550b03..f8eafcf1f3 100644 > >> --- a/include/libc-symbols.h > >> +++ b/include/libc-symbols.h > >> @@ -373,17 +373,29 @@ for linking") > >> > >> /* These are all done the same way in ELF. > >> There is a new section created for each set. */ > >> -#ifdef SHARED > >> +#ifdef HAVE_GCC_RETAIN > >> +# ifdef SHARED > >> /* When building a shared library, make the set section writable, > >> - because it will need to be relocated at run time anyway. */ > >> -# define _elf_set_element(set, symbol) \ > >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > > > >You should define __attribute_used_and_retain__ instead. > > > >> + because it will need to be relocated at run time anyway. */ > >> +# define _elf_set_element(set, symbol) \ > >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> + __attribute__ ((used, retain, section (#set))) = &(symbol) > >> +# else > >> +# define _elf_set_element(set, symbol) \ > >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> + __attribute__ ((used, retain, section (#set))) = &(symbol) > >> +# endif > >> #else > >> -# define _elf_set_element(set, symbol) \ > >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> -#endif > >> +# ifdef SHARED > >> +# define _elf_set_element(set, symbol) \ > >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> + __attribute__ ((used, section (#set))) = &(symbol) > >> +# else > >> +# define _elf_set_element(set, symbol) \ > >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> + __attribute__ ((used, section (#set))) = &(symbol) > >> +# endif > >> +#endif /* HAVE_GCC_RETAIN */ > >> > >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> be able to use the set's contents. */ > >> -- > >> 2.31.0.rc2.261.g7f71774620-goog > >> > > > >libc.a is an installed file. Does this work with older linkers? > > > >-- > >H.J. > > How about > > /* These are all done the same way in ELF. > There is a new section created for each set. */ > #ifdef HAVE_GCC_RETAIN > # define attribute_used_retain_section(sec) \ > __attribute__ ((used, retain, section (sec))) > #else __attribute_used_and_retain__ is more flex and can be used without section. > # define attribute_used_retain_section(sec) \ > __attribute__ ((used, section (sec))) > #endif > #ifdef SHARED > /* When building a shared library, make the set section writable, > because it will need to be relocated at run time anyway. */ > # define _elf_set_element(set, symbol) \ > static const void *__elf_set_##set##_element_##symbol##__ \ > attribute_used_retain_section(#set) = &(symbol) > #else > # define _elf_set_element(set, symbol) \ > static const void *const __elf_set_##set##_element_##symbol##__ \ > attribute_used_retain_section(#set) = &(symbol) > #endif > ? Yes, older linkers just ignore unknown section flags. That is the ELF spirit. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v2] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-22 20:28 ` H.J. Lu @ 2021-03-23 4:14 ` Fangrui Song 2021-03-29 23:11 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-03-23 4:14 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-03-22, H.J. Lu wrote: >On Sun, Mar 21, 2021 at 9:40 PM Fangrui Song <maskray@google.com> wrote: >> >> On 2021-03-21, H.J. Lu wrote: >> >On Sun, Mar 21, 2021 at 9:01 PM Fangrui Song via Libc-alpha >> ><libc-alpha@sourceware.org> wrote: >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined >> >> variables will be retained by the linker. >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> >> will not be optimized out; 'retain' prevents section garbage collection >> >> if the linker support SHF_GNU_RETAIN. >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> >> identifier name sections to be GCed even if there are live >> >> __start_/__stop_ references. >> >> >> >> Without the change, there are some static linking problems, e.g. >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> >> stdout is not flushed on exit. >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> >> --- >> >> config.h.in | 3 +++ >> >> configure | 23 +++++++++++++++++++++++ >> >> configure.ac | 16 ++++++++++++++++ >> >> include/libc-symbols.h | 30 +++++++++++++++++++++--------- >> >> 4 files changed, 63 insertions(+), 9 deletions(-) >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> index f21bf04e47..cc875e90f9 100644 >> >> --- a/config.h.in >> >> +++ b/config.h.in >> >> @@ -187,6 +187,9 @@ >> >> /* Define if gcc supports attribute ifunc. */ >> >> #undef HAVE_GCC_IFUNC >> >> >> >> +/* Define if gcc supports attribute retain. */ >> >> +#undef HAVE_GCC_RETAIN >> >> + >> >> /* Define if the linker defines __ehdr_start. */ >> >> #undef HAVE_EHDR_START >> >> >> >> diff --git a/configure b/configure >> >> index 37cef37413..28494de748 100755 >> >> --- a/configure >> >> +++ b/configure >> >> @@ -4105,6 +4105,29 @@ fi >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 >> >> +$as_echo_n "checking for gcc attribute retain support... " >&6; } >> >> +if ${libc_cv_gcc_retain+:} false; then : >> >> + $as_echo_n "(cached) " >&6 >> >> +else >> >> + cat > conftest.c <<EOF >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> +EOF >> >> +libc_cv_gcc_retain=no >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> + 2>&5 ; then >> >> + libc_cv_gcc_retain=yes >> >> +fi >> >> +rm -f conftest* >> >> +fi >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 >> >> +$as_echo "$libc_cv_gcc_retain" >&6; } >> >> +if test $libc_cv_gcc_retain = yes; then >> >> + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h >> >> + >> >> +fi >> >> + >> >> # Check if gcc warns about alias for function with incompatible types. >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> diff --git a/configure.ac b/configure.ac >> >> index 16b15b6f90..94ad713820 100644 >> >> --- a/configure.ac >> >> +++ b/configure.ac >> >> @@ -707,6 +707,22 @@ fi >> >> rm -f conftest*]) >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. >> >> +AC_CACHE_CHECK([for gcc attribute retain support], >> >> + libc_cv_gcc_retain, [dnl >> >> +cat > conftest.c <<EOF >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> +EOF >> >> +libc_cv_gcc_retain=no >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> + libc_cv_gcc_retain=yes >> >> +fi >> >> +rm -f conftest*]) >> >> +if test $libc_cv_gcc_retain = yes; then >> >> + AC_DEFINE(HAVE_GCC_RETAIN) >> >> +fi >> >> + >> >> # Check if gcc warns about alias for function with incompatible types. >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> index c83e550b03..f8eafcf1f3 100644 >> >> --- a/include/libc-symbols.h >> >> +++ b/include/libc-symbols.h >> >> @@ -373,17 +373,29 @@ for linking") >> >> >> >> /* These are all done the same way in ELF. >> >> There is a new section created for each set. */ >> >> -#ifdef SHARED >> >> +#ifdef HAVE_GCC_RETAIN >> >> +# ifdef SHARED >> >> /* When building a shared library, make the set section writable, >> >> - because it will need to be relocated at run time anyway. */ >> >> -# define _elf_set_element(set, symbol) \ >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> > >> >You should define __attribute_used_and_retain__ instead. >> > >> >> + because it will need to be relocated at run time anyway. */ >> >> +# define _elf_set_element(set, symbol) \ >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> + __attribute__ ((used, retain, section (#set))) = &(symbol) >> >> +# else >> >> +# define _elf_set_element(set, symbol) \ >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> + __attribute__ ((used, retain, section (#set))) = &(symbol) >> >> +# endif >> >> #else >> >> -# define _elf_set_element(set, symbol) \ >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> -#endif >> >> +# ifdef SHARED >> >> +# define _elf_set_element(set, symbol) \ >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> + __attribute__ ((used, section (#set))) = &(symbol) >> >> +# else >> >> +# define _elf_set_element(set, symbol) \ >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> + __attribute__ ((used, section (#set))) = &(symbol) >> >> +# endif >> >> +#endif /* HAVE_GCC_RETAIN */ >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> be able to use the set's contents. */ >> >> -- >> >> 2.31.0.rc2.261.g7f71774620-goog >> >> >> > >> >libc.a is an installed file. Does this work with older linkers? >> > >> >-- >> >H.J. >> >> How about >> >> /* These are all done the same way in ELF. >> There is a new section created for each set. */ >> #ifdef HAVE_GCC_RETAIN >> # define attribute_used_retain_section(sec) \ >> __attribute__ ((used, retain, section (sec))) >> #else > >__attribute_used_and_retain__ is more flex and can be used >without section. > >> # define attribute_used_retain_section(sec) \ >> __attribute__ ((used, section (sec))) >> #endif >> #ifdef SHARED >> /* When building a shared library, make the set section writable, >> because it will need to be relocated at run time anyway. */ >> # define _elf_set_element(set, symbol) \ >> static const void *__elf_set_##set##_element_##symbol##__ \ >> attribute_used_retain_section(#set) = &(symbol) >> #else >> # define _elf_set_element(set, symbol) \ >> static const void *const __elf_set_##set##_element_##symbol##__ \ >> attribute_used_retain_section(#set) = &(symbol) >> #endif >> ? Yes, older linkers just ignore unknown section flags. That is the ELF spirit. > > > >-- >H.J. +#ifdef HAVE_GCC_RETAIN +# define attribute_used_retain __attribute__ ((__used__, __retain__)) +#else +# define attribute_used_retain __attribute__ ((__used__)) +#endif + /* Symbol set support macros. */ /* Make SYMBOL, which is in the text segment, an element of SET. */ @@ -377,12 +383,12 @@ for linking") /* When building a shared library, make the set section writable, because it will need to be relocated at run time anyway. */ # define _elf_set_element(set, symbol) \ - static const void *__elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *__elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #else # define _elf_set_element(set, symbol) \ - static const void *const __elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *const __elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #endif ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v2] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-23 4:14 ` Fangrui Song @ 2021-03-29 23:11 ` H.J. Lu 2021-03-29 23:24 ` [PATCH v3] " Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-03-29 23:11 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Mon, Mar 22, 2021 at 9:15 PM Fangrui Song <maskray@google.com> wrote: > > > On 2021-03-22, H.J. Lu wrote: > >On Sun, Mar 21, 2021 at 9:40 PM Fangrui Song <maskray@google.com> wrote: > >> > >> On 2021-03-21, H.J. Lu wrote: > >> >On Sun, Mar 21, 2021 at 9:01 PM Fangrui Song via Libc-alpha > >> ><libc-alpha@sourceware.org> wrote: > >> >> > >> >> So that text_set_element/data_set_element/bss_set_element defined > >> >> variables will be retained by the linker. > >> >> > >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> >> will not be optimized out; 'retain' prevents section garbage collection > >> >> if the linker support SHF_GNU_RETAIN. > >> >> > >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> >> identifier name sections to be GCed even if there are live > >> >> __start_/__stop_ references. > >> >> > >> >> Without the change, there are some static linking problems, e.g. > >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> >> stdout is not flushed on exit. > >> >> > >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> >> --- > >> >> config.h.in | 3 +++ > >> >> configure | 23 +++++++++++++++++++++++ > >> >> configure.ac | 16 ++++++++++++++++ > >> >> include/libc-symbols.h | 30 +++++++++++++++++++++--------- > >> >> 4 files changed, 63 insertions(+), 9 deletions(-) > >> >> > >> >> diff --git a/config.h.in b/config.h.in > >> >> index f21bf04e47..cc875e90f9 100644 > >> >> --- a/config.h.in > >> >> +++ b/config.h.in > >> >> @@ -187,6 +187,9 @@ > >> >> /* Define if gcc supports attribute ifunc. */ > >> >> #undef HAVE_GCC_IFUNC > >> >> > >> >> +/* Define if gcc supports attribute retain. */ > >> >> +#undef HAVE_GCC_RETAIN > >> >> + > >> >> /* Define if the linker defines __ehdr_start. */ > >> >> #undef HAVE_EHDR_START > >> >> > >> >> diff --git a/configure b/configure > >> >> index 37cef37413..28494de748 100755 > >> >> --- a/configure > >> >> +++ b/configure > >> >> @@ -4105,6 +4105,29 @@ fi > >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> > >> >> > >> >> +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > >> >> +$as_echo_n "checking for gcc attribute retain support... " >&6; } > >> >> +if ${libc_cv_gcc_retain+:} false; then : > >> >> + $as_echo_n "(cached) " >&6 > >> >> +else > >> >> + cat > conftest.c <<EOF > >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> +EOF > >> >> +libc_cv_gcc_retain=no > >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> + 2>&5 ; then > >> >> + libc_cv_gcc_retain=yes > >> >> +fi > >> >> +rm -f conftest* > >> >> +fi > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > >> >> +$as_echo "$libc_cv_gcc_retain" >&6; } > >> >> +if test $libc_cv_gcc_retain = yes; then > >> >> + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > >> >> + > >> >> +fi > >> >> + > >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> diff --git a/configure.ac b/configure.ac > >> >> index 16b15b6f90..94ad713820 100644 > >> >> --- a/configure.ac > >> >> +++ b/configure.ac > >> >> @@ -707,6 +707,22 @@ fi > >> >> rm -f conftest*]) > >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> > >> >> +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > >> >> +AC_CACHE_CHECK([for gcc attribute retain support], > >> >> + libc_cv_gcc_retain, [dnl > >> >> +cat > conftest.c <<EOF > >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> +EOF > >> >> +libc_cv_gcc_retain=no > >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> + libc_cv_gcc_retain=yes > >> >> +fi > >> >> +rm -f conftest*]) > >> >> +if test $libc_cv_gcc_retain = yes; then > >> >> + AC_DEFINE(HAVE_GCC_RETAIN) > >> >> +fi > >> >> + > >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> index c83e550b03..f8eafcf1f3 100644 > >> >> --- a/include/libc-symbols.h > >> >> +++ b/include/libc-symbols.h > >> >> @@ -373,17 +373,29 @@ for linking") > >> >> > >> >> /* These are all done the same way in ELF. > >> >> There is a new section created for each set. */ > >> >> -#ifdef SHARED > >> >> +#ifdef HAVE_GCC_RETAIN > >> >> +# ifdef SHARED > >> >> /* When building a shared library, make the set section writable, > >> >> - because it will need to be relocated at run time anyway. */ > >> >> -# define _elf_set_element(set, symbol) \ > >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> > > >> >You should define __attribute_used_and_retain__ instead. > >> > > >> >> + because it will need to be relocated at run time anyway. */ > >> >> +# define _elf_set_element(set, symbol) \ > >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> + __attribute__ ((used, retain, section (#set))) = &(symbol) > >> >> +# else > >> >> +# define _elf_set_element(set, symbol) \ > >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> + __attribute__ ((used, retain, section (#set))) = &(symbol) > >> >> +# endif > >> >> #else > >> >> -# define _elf_set_element(set, symbol) \ > >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> -#endif > >> >> +# ifdef SHARED > >> >> +# define _elf_set_element(set, symbol) \ > >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> + __attribute__ ((used, section (#set))) = &(symbol) > >> >> +# else > >> >> +# define _elf_set_element(set, symbol) \ > >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> + __attribute__ ((used, section (#set))) = &(symbol) > >> >> +# endif > >> >> +#endif /* HAVE_GCC_RETAIN */ > >> >> > >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> be able to use the set's contents. */ > >> >> -- > >> >> 2.31.0.rc2.261.g7f71774620-goog > >> >> > >> > > >> >libc.a is an installed file. Does this work with older linkers? > >> > > >> >-- > >> >H.J. > >> > >> How about > >> > >> /* These are all done the same way in ELF. > >> There is a new section created for each set. */ > >> #ifdef HAVE_GCC_RETAIN > >> # define attribute_used_retain_section(sec) \ > >> __attribute__ ((used, retain, section (sec))) > >> #else > > > >__attribute_used_and_retain__ is more flex and can be used > >without section. > > > >> # define attribute_used_retain_section(sec) \ > >> __attribute__ ((used, section (sec))) > >> #endif > >> #ifdef SHARED > >> /* When building a shared library, make the set section writable, > >> because it will need to be relocated at run time anyway. */ > >> # define _elf_set_element(set, symbol) \ > >> static const void *__elf_set_##set##_element_##symbol##__ \ > >> attribute_used_retain_section(#set) = &(symbol) > >> #else > >> # define _elf_set_element(set, symbol) \ > >> static const void *const __elf_set_##set##_element_##symbol##__ \ > >> attribute_used_retain_section(#set) = &(symbol) > >> #endif > >> ? Yes, older linkers just ignore unknown section flags. That is the ELF spirit. > > > > > > > >-- > >H.J. > > +#ifdef HAVE_GCC_RETAIN > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > +#else > +# define attribute_used_retain __attribute__ ((__used__)) > +#endif > + > /* Symbol set support macros. */ > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > @@ -377,12 +383,12 @@ for linking") > /* When building a shared library, make the set section writable, > because it will need to be relocated at run time anyway. */ > # define _elf_set_element(set, symbol) \ > - static const void *__elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *__elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #else > # define _elf_set_element(set, symbol) \ > - static const void *const __elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #endif > Please submit a v2 patch. Thanks. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v3] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-29 23:11 ` H.J. Lu @ 2021-03-29 23:24 ` Fangrui Song 2021-03-30 18:17 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-03-29 23:24 UTC (permalink / raw) To: libc-alpha, Florian Weimer, H . J . Lu ; +Cc: Fangrui Song So that text_set_element/data_set_element/bss_set_element defined variables will be retained by the linker. Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable will not be optimized out; 'retain' prevents section garbage collection if the linker support SHF_GNU_RETAIN. GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C identifier name sections to be GCed even if there are live __start_/__stop_ references. Without the change, there are some static linking problems, e.g. _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so stdout is not flushed on exit. Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). --- Changes in v1 -> v2: * Define attribute_used_retain_section Changes in v2 -> v3: * Use attribute_used_retain instead attribute_used_retain_section --- config.h.in | 3 +++ configure | 23 +++++++++++++++++++++++ configure.ac | 16 ++++++++++++++++ include/libc-symbols.h | 14 ++++++++++---- 4 files changed, 52 insertions(+), 4 deletions(-) diff --git a/config.h.in b/config.h.in index ca1547ae67..95af1ef229 100644 --- a/config.h.in +++ b/config.h.in @@ -187,6 +187,9 @@ /* Define if gcc supports attribute ifunc. */ #undef HAVE_GCC_IFUNC +/* Define if gcc supports attribute retain. */ +#undef HAVE_GCC_RETAIN + /* Define if the linker defines __ehdr_start. */ #undef HAVE_EHDR_START diff --git a/configure b/configure index fcf43bf7de..6a6b8ac264 100755 --- a/configure +++ b/configure @@ -4105,6 +4105,29 @@ fi $as_echo "$libc_cv_textrel_ifunc" >&6; } +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 +$as_echo_n "checking for gcc attribute retain support... " >&6; } +if ${libc_cv_gcc_retain+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gcc_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ + 2>&5 ; then + libc_cv_gcc_retain=yes +fi +rm -f conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 +$as_echo "$libc_cv_gcc_retain" >&6; } +if test $libc_cv_gcc_retain = yes; then + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h + +fi + # Check if gcc warns about alias for function with incompatible types. { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } diff --git a/configure.ac b/configure.ac index fce967f2c2..031b8c3fb3 100644 --- a/configure.ac +++ b/configure.ac @@ -707,6 +707,22 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_textrel_ifunc) +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. +AC_CACHE_CHECK([for gcc attribute retain support], + libc_cv_gcc_retain, [dnl +cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gcc_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ + 2>&AS_MESSAGE_LOG_FD ; then + libc_cv_gcc_retain=yes +fi +rm -f conftest*]) +if test $libc_cv_gcc_retain = yes; then + AC_DEFINE(HAVE_GCC_RETAIN) +fi + # Check if gcc warns about alias for function with incompatible types. AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], libc_cv_gcc_incompatible_alias, [dnl diff --git a/include/libc-symbols.h b/include/libc-symbols.h index 546fc26a7b..b311c90f0c 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -352,6 +352,12 @@ for linking") \f */ +#ifdef HAVE_GCC_RETAIN +# define attribute_used_retain __attribute__ ((__used__, __retain__)) +#else +# define attribute_used_retain __attribute__ ((__used__)) +#endif + /* Symbol set support macros. */ /* Make SYMBOL, which is in the text segment, an element of SET. */ @@ -367,12 +373,12 @@ for linking") /* When building a shared library, make the set section writable, because it will need to be relocated at run time anyway. */ # define _elf_set_element(set, symbol) \ - static const void *__elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *__elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #else # define _elf_set_element(set, symbol) \ - static const void *const __elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *const __elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #endif /* Define SET as a symbol set. This may be required (it is in a.out) to -- 2.31.0.291.g576ba9dcdaf-goog ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-29 23:24 ` [PATCH v3] " Fangrui Song @ 2021-03-30 18:17 ` H.J. Lu 2021-03-30 19:17 ` Fāng-ruì Sòng 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-03-30 18:17 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Mon, Mar 29, 2021 at 4:24 PM Fangrui Song <maskray@google.com> wrote: > > So that text_set_element/data_set_element/bss_set_element defined > variables will be retained by the linker. > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > will not be optimized out; 'retain' prevents section garbage collection > if the linker support SHF_GNU_RETAIN. > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > identifier name sections to be GCed even if there are live > __start_/__stop_ references. > > Without the change, there are some static linking problems, e.g. > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > stdout is not flushed on exit. > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > --- > Changes in v1 -> v2: > * Define attribute_used_retain_section > Changes in v2 -> v3: > * Use attribute_used_retain instead attribute_used_retain_section > --- > config.h.in | 3 +++ > configure | 23 +++++++++++++++++++++++ > configure.ac | 16 ++++++++++++++++ > include/libc-symbols.h | 14 ++++++++++---- > 4 files changed, 52 insertions(+), 4 deletions(-) > > diff --git a/config.h.in b/config.h.in > index ca1547ae67..95af1ef229 100644 > --- a/config.h.in > +++ b/config.h.in > @@ -187,6 +187,9 @@ > /* Define if gcc supports attribute ifunc. */ > #undef HAVE_GCC_IFUNC > > +/* Define if gcc supports attribute retain. */ > +#undef HAVE_GCC_RETAIN > + > /* Define if the linker defines __ehdr_start. */ > #undef HAVE_EHDR_START > > diff --git a/configure b/configure > index fcf43bf7de..6a6b8ac264 100755 > --- a/configure > +++ b/configure > @@ -4105,6 +4105,29 @@ fi > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > +$as_echo_n "checking for gcc attribute retain support... " >&6; } > +if ${libc_cv_gcc_retain+:} false; then : > + $as_echo_n "(cached) " >&6 > +else > + cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gcc_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > + 2>&5 ; then > + libc_cv_gcc_retain=yes > +fi > +rm -f conftest* > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > +$as_echo "$libc_cv_gcc_retain" >&6; } > +if test $libc_cv_gcc_retain = yes; then > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > + > +fi > + > # Check if gcc warns about alias for function with incompatible types. > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > diff --git a/configure.ac b/configure.ac > index fce967f2c2..031b8c3fb3 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -707,6 +707,22 @@ fi > rm -f conftest*]) > AC_SUBST(libc_cv_textrel_ifunc) > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > +AC_CACHE_CHECK([for gcc attribute retain support], > + libc_cv_gcc_retain, [dnl > +cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gcc_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > + 2>&AS_MESSAGE_LOG_FD ; then > + libc_cv_gcc_retain=yes > +fi > +rm -f conftest*]) > +if test $libc_cv_gcc_retain = yes; then > + AC_DEFINE(HAVE_GCC_RETAIN) > +fi > + > # Check if gcc warns about alias for function with incompatible types. > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > libc_cv_gcc_incompatible_alias, [dnl > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > index 546fc26a7b..b311c90f0c 100644 > --- a/include/libc-symbols.h > +++ b/include/libc-symbols.h > @@ -352,6 +352,12 @@ for linking") > > */ > > +#ifdef HAVE_GCC_RETAIN > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > +#else > +# define attribute_used_retain __attribute__ ((__used__)) > +#endif > + > /* Symbol set support macros. */ > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > @@ -367,12 +373,12 @@ for linking") > /* When building a shared library, make the set section writable, > because it will need to be relocated at run time anyway. */ > # define _elf_set_element(set, symbol) \ > - static const void *__elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *__elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #else > # define _elf_set_element(set, symbol) \ > - static const void *const __elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #endif > > /* Define SET as a symbol set. This may be required (it is in a.out) to > -- > 2.31.0.291.g576ba9dcdaf-goog > Need gc-sections tests for linkers with and without -z start-stop-gc. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-30 18:17 ` H.J. Lu @ 2021-03-30 19:17 ` Fāng-ruì Sòng 2021-03-30 19:30 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fāng-ruì Sòng @ 2021-03-30 19:17 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On Tue, Mar 30, 2021 at 11:17 AM H.J. Lu <hjl.tools@gmail.com> wrote: > > On Mon, Mar 29, 2021 at 4:24 PM Fangrui Song <maskray@google.com> wrote: > > > > So that text_set_element/data_set_element/bss_set_element defined > > variables will be retained by the linker. > > > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > > will not be optimized out; 'retain' prevents section garbage collection > > if the linker support SHF_GNU_RETAIN. > > > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > > identifier name sections to be GCed even if there are live > > __start_/__stop_ references. > > > > Without the change, there are some static linking problems, e.g. > > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > > stdout is not flushed on exit. > > > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > > --- > > Changes in v1 -> v2: > > * Define attribute_used_retain_section > > Changes in v2 -> v3: > > * Use attribute_used_retain instead attribute_used_retain_section > > --- > > config.h.in | 3 +++ > > configure | 23 +++++++++++++++++++++++ > > configure.ac | 16 ++++++++++++++++ > > include/libc-symbols.h | 14 ++++++++++---- > > 4 files changed, 52 insertions(+), 4 deletions(-) > > > > diff --git a/config.h.in b/config.h.in > > index ca1547ae67..95af1ef229 100644 > > --- a/config.h.in > > +++ b/config.h.in > > @@ -187,6 +187,9 @@ > > /* Define if gcc supports attribute ifunc. */ > > #undef HAVE_GCC_IFUNC > > > > +/* Define if gcc supports attribute retain. */ > > +#undef HAVE_GCC_RETAIN > > + > > /* Define if the linker defines __ehdr_start. */ > > #undef HAVE_EHDR_START > > > > diff --git a/configure b/configure > > index fcf43bf7de..6a6b8ac264 100755 > > --- a/configure > > +++ b/configure > > @@ -4105,6 +4105,29 @@ fi > > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > > > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > > +$as_echo_n "checking for gcc attribute retain support... " >&6; } > > +if ${libc_cv_gcc_retain+:} false; then : > > + $as_echo_n "(cached) " >&6 > > +else > > + cat > conftest.c <<EOF > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > +EOF > > +libc_cv_gcc_retain=no > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > > + 2>&5 ; then > > + libc_cv_gcc_retain=yes > > +fi > > +rm -f conftest* > > +fi > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > > +$as_echo "$libc_cv_gcc_retain" >&6; } > > +if test $libc_cv_gcc_retain = yes; then > > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > > + > > +fi > > + > > # Check if gcc warns about alias for function with incompatible types. > > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > > diff --git a/configure.ac b/configure.ac > > index fce967f2c2..031b8c3fb3 100644 > > --- a/configure.ac > > +++ b/configure.ac > > @@ -707,6 +707,22 @@ fi > > rm -f conftest*]) > > AC_SUBST(libc_cv_textrel_ifunc) > > > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > > +AC_CACHE_CHECK([for gcc attribute retain support], > > + libc_cv_gcc_retain, [dnl > > +cat > conftest.c <<EOF > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > +EOF > > +libc_cv_gcc_retain=no > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > > + 2>&AS_MESSAGE_LOG_FD ; then > > + libc_cv_gcc_retain=yes > > +fi > > +rm -f conftest*]) > > +if test $libc_cv_gcc_retain = yes; then > > + AC_DEFINE(HAVE_GCC_RETAIN) > > +fi > > + > > # Check if gcc warns about alias for function with incompatible types. > > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > > libc_cv_gcc_incompatible_alias, [dnl > > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > > index 546fc26a7b..b311c90f0c 100644 > > --- a/include/libc-symbols.h > > +++ b/include/libc-symbols.h > > @@ -352,6 +352,12 @@ for linking") > > > > */ > > > > +#ifdef HAVE_GCC_RETAIN > > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > > +#else > > +# define attribute_used_retain __attribute__ ((__used__)) > > +#endif > > + > > /* Symbol set support macros. */ > > > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > > @@ -367,12 +373,12 @@ for linking") > > /* When building a shared library, make the set section writable, > > because it will need to be relocated at run time anyway. */ > > # define _elf_set_element(set, symbol) \ > > - static const void *__elf_set_##set##_element_##symbol##__ \ > > - __attribute__ ((used, section (#set))) = &(symbol) > > + static const void *__elf_set_##set##_element_##symbol##__ \ > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > #else > > # define _elf_set_element(set, symbol) \ > > - static const void *const __elf_set_##set##_element_##symbol##__ \ > > - __attribute__ ((used, section (#set))) = &(symbol) > > + static const void *const __elf_set_##set##_element_##symbol##__ \ > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > #endif > > > > /* Define SET as a symbol set. This may be required (it is in a.out) to > > -- > > 2.31.0.291.g576ba9dcdaf-goog > > > > Need gc-sections tests for linkers with and without -z start-stop-gc. > > -- > H.J. I don't know how to add such a test... It needs to check flush at ext time but I cannot find a template in libio/tst-* ... ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-30 19:17 ` Fāng-ruì Sòng @ 2021-03-30 19:30 ` H.J. Lu 2021-03-31 4:34 ` Fāng-ruì Sòng 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-03-30 19:30 UTC (permalink / raw) To: Fāng-ruì Sòng; +Cc: GNU C Library, Florian Weimer On Tue, Mar 30, 2021 at 12:17 PM Fāng-ruì Sòng <maskray@google.com> wrote: > > On Tue, Mar 30, 2021 at 11:17 AM H.J. Lu <hjl.tools@gmail.com> wrote: > > > > On Mon, Mar 29, 2021 at 4:24 PM Fangrui Song <maskray@google.com> wrote: > > > > > > So that text_set_element/data_set_element/bss_set_element defined > > > variables will be retained by the linker. > > > > > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > > > will not be optimized out; 'retain' prevents section garbage collection > > > if the linker support SHF_GNU_RETAIN. > > > > > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > > > identifier name sections to be GCed even if there are live > > > __start_/__stop_ references. > > > > > > Without the change, there are some static linking problems, e.g. > > > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > > > stdout is not flushed on exit. > > > > > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > > > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > > > --- > > > Changes in v1 -> v2: > > > * Define attribute_used_retain_section > > > Changes in v2 -> v3: > > > * Use attribute_used_retain instead attribute_used_retain_section > > > --- > > > config.h.in | 3 +++ > > > configure | 23 +++++++++++++++++++++++ > > > configure.ac | 16 ++++++++++++++++ > > > include/libc-symbols.h | 14 ++++++++++---- > > > 4 files changed, 52 insertions(+), 4 deletions(-) > > > > > > diff --git a/config.h.in b/config.h.in > > > index ca1547ae67..95af1ef229 100644 > > > --- a/config.h.in > > > +++ b/config.h.in > > > @@ -187,6 +187,9 @@ > > > /* Define if gcc supports attribute ifunc. */ > > > #undef HAVE_GCC_IFUNC > > > > > > +/* Define if gcc supports attribute retain. */ > > > +#undef HAVE_GCC_RETAIN > > > + > > > /* Define if the linker defines __ehdr_start. */ > > > #undef HAVE_EHDR_START > > > > > > diff --git a/configure b/configure > > > index fcf43bf7de..6a6b8ac264 100755 > > > --- a/configure > > > +++ b/configure > > > @@ -4105,6 +4105,29 @@ fi > > > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > > > > > > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > > > +$as_echo_n "checking for gcc attribute retain support... " >&6; } > > > +if ${libc_cv_gcc_retain+:} false; then : > > > + $as_echo_n "(cached) " >&6 > > > +else > > > + cat > conftest.c <<EOF > > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > > +EOF > > > +libc_cv_gcc_retain=no > > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > > > + 2>&5 ; then > > > + libc_cv_gcc_retain=yes > > > +fi > > > +rm -f conftest* > > > +fi > > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > > > +$as_echo "$libc_cv_gcc_retain" >&6; } > > > +if test $libc_cv_gcc_retain = yes; then > > > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > > > + > > > +fi > > > + > > > # Check if gcc warns about alias for function with incompatible types. > > > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > > > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > > > diff --git a/configure.ac b/configure.ac > > > index fce967f2c2..031b8c3fb3 100644 > > > --- a/configure.ac > > > +++ b/configure.ac > > > @@ -707,6 +707,22 @@ fi > > > rm -f conftest*]) > > > AC_SUBST(libc_cv_textrel_ifunc) > > > > > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > > > +AC_CACHE_CHECK([for gcc attribute retain support], > > > + libc_cv_gcc_retain, [dnl > > > +cat > conftest.c <<EOF > > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > > +EOF > > > +libc_cv_gcc_retain=no > > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > > > + 2>&AS_MESSAGE_LOG_FD ; then > > > + libc_cv_gcc_retain=yes > > > +fi > > > +rm -f conftest*]) > > > +if test $libc_cv_gcc_retain = yes; then > > > + AC_DEFINE(HAVE_GCC_RETAIN) > > > +fi > > > + > > > # Check if gcc warns about alias for function with incompatible types. > > > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > > > libc_cv_gcc_incompatible_alias, [dnl > > > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > > > index 546fc26a7b..b311c90f0c 100644 > > > --- a/include/libc-symbols.h > > > +++ b/include/libc-symbols.h > > > @@ -352,6 +352,12 @@ for linking") > > > > > > */ > > > > > > +#ifdef HAVE_GCC_RETAIN > > > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > > > +#else > > > +# define attribute_used_retain __attribute__ ((__used__)) > > > +#endif > > > + > > > /* Symbol set support macros. */ > > > > > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > > > @@ -367,12 +373,12 @@ for linking") > > > /* When building a shared library, make the set section writable, > > > because it will need to be relocated at run time anyway. */ > > > # define _elf_set_element(set, symbol) \ > > > - static const void *__elf_set_##set##_element_##symbol##__ \ > > > - __attribute__ ((used, section (#set))) = &(symbol) > > > + static const void *__elf_set_##set##_element_##symbol##__ \ > > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > > #else > > > # define _elf_set_element(set, symbol) \ > > > - static const void *const __elf_set_##set##_element_##symbol##__ \ > > > - __attribute__ ((used, section (#set))) = &(symbol) > > > + static const void *const __elf_set_##set##_element_##symbol##__ \ > > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > > #endif > > > > > > /* Define SET as a symbol set. This may be required (it is in a.out) to > > > -- > > > 2.31.0.291.g576ba9dcdaf-goog > > > > > > > Need gc-sections tests for linkers with and without -z start-stop-gc. > > > > -- > > H.J. > > I don't know how to add such a test... It needs to check flush at ext > time but I cannot find a template in libio/tst-* ... You can add a special rule to check for linker output with --print-gc-sections. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-30 19:30 ` H.J. Lu @ 2021-03-31 4:34 ` Fāng-ruì Sòng 2021-03-31 16:17 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fāng-ruì Sòng @ 2021-03-31 4:34 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-03-30, H.J. Lu wrote: >On Tue, Mar 30, 2021 at 12:17 PM Fāng-ruì Sòng <maskray@google.com> wrote: >> >> On Tue, Mar 30, 2021 at 11:17 AM H.J. Lu <hjl.tools@gmail.com> wrote: >> > >> > On Mon, Mar 29, 2021 at 4:24 PM Fangrui Song <maskray@google.com> wrote: >> > > >> > > So that text_set_element/data_set_element/bss_set_element defined >> > > variables will be retained by the linker. >> > > >> > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> > > will not be optimized out; 'retain' prevents section garbage collection >> > > if the linker support SHF_GNU_RETAIN. >> > > >> > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> > > identifier name sections to be GCed even if there are live >> > > __start_/__stop_ references. >> > > >> > > Without the change, there are some static linking problems, e.g. >> > > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> > > stdout is not flushed on exit. >> > > >> > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> > > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> > > --- >> > > Changes in v1 -> v2: >> > > * Define attribute_used_retain_section >> > > Changes in v2 -> v3: >> > > * Use attribute_used_retain instead attribute_used_retain_section >> > > --- >> > > config.h.in | 3 +++ >> > > configure | 23 +++++++++++++++++++++++ >> > > configure.ac | 16 ++++++++++++++++ >> > > include/libc-symbols.h | 14 ++++++++++---- >> > > 4 files changed, 52 insertions(+), 4 deletions(-) >> > > >> > > diff --git a/config.h.in b/config.h.in >> > > index ca1547ae67..95af1ef229 100644 >> > > --- a/config.h.in >> > > +++ b/config.h.in >> > > @@ -187,6 +187,9 @@ >> > > /* Define if gcc supports attribute ifunc. */ >> > > #undef HAVE_GCC_IFUNC >> > > >> > > +/* Define if gcc supports attribute retain. */ >> > > +#undef HAVE_GCC_RETAIN >> > > + >> > > /* Define if the linker defines __ehdr_start. */ >> > > #undef HAVE_EHDR_START >> > > >> > > diff --git a/configure b/configure >> > > index fcf43bf7de..6a6b8ac264 100755 >> > > --- a/configure >> > > +++ b/configure >> > > @@ -4105,6 +4105,29 @@ fi >> > > $as_echo "$libc_cv_textrel_ifunc" >&6; } >> > > >> > > >> > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. >> > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 >> > > +$as_echo_n "checking for gcc attribute retain support... " >&6; } >> > > +if ${libc_cv_gcc_retain+:} false; then : >> > > + $as_echo_n "(cached) " >&6 >> > > +else >> > > + cat > conftest.c <<EOF >> > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> > > +EOF >> > > +libc_cv_gcc_retain=no >> > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> > > + 2>&5 ; then >> > > + libc_cv_gcc_retain=yes >> > > +fi >> > > +rm -f conftest* >> > > +fi >> > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 >> > > +$as_echo "$libc_cv_gcc_retain" >&6; } >> > > +if test $libc_cv_gcc_retain = yes; then >> > > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h >> > > + >> > > +fi >> > > + >> > > # Check if gcc warns about alias for function with incompatible types. >> > > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> > > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> > > diff --git a/configure.ac b/configure.ac >> > > index fce967f2c2..031b8c3fb3 100644 >> > > --- a/configure.ac >> > > +++ b/configure.ac >> > > @@ -707,6 +707,22 @@ fi >> > > rm -f conftest*]) >> > > AC_SUBST(libc_cv_textrel_ifunc) >> > > >> > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. >> > > +AC_CACHE_CHECK([for gcc attribute retain support], >> > > + libc_cv_gcc_retain, [dnl >> > > +cat > conftest.c <<EOF >> > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> > > +EOF >> > > +libc_cv_gcc_retain=no >> > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> > > + 2>&AS_MESSAGE_LOG_FD ; then >> > > + libc_cv_gcc_retain=yes >> > > +fi >> > > +rm -f conftest*]) >> > > +if test $libc_cv_gcc_retain = yes; then >> > > + AC_DEFINE(HAVE_GCC_RETAIN) >> > > +fi >> > > + >> > > # Check if gcc warns about alias for function with incompatible types. >> > > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> > > libc_cv_gcc_incompatible_alias, [dnl >> > > diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> > > index 546fc26a7b..b311c90f0c 100644 >> > > --- a/include/libc-symbols.h >> > > +++ b/include/libc-symbols.h >> > > @@ -352,6 +352,12 @@ for linking") >> > > >> > > */ >> > > >> > > +#ifdef HAVE_GCC_RETAIN >> > > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> > > +#else >> > > +# define attribute_used_retain __attribute__ ((__used__)) >> > > +#endif >> > > + >> > > /* Symbol set support macros. */ >> > > >> > > /* Make SYMBOL, which is in the text segment, an element of SET. */ >> > > @@ -367,12 +373,12 @@ for linking") >> > > /* When building a shared library, make the set section writable, >> > > because it will need to be relocated at run time anyway. */ >> > > # define _elf_set_element(set, symbol) \ >> > > - static const void *__elf_set_##set##_element_##symbol##__ \ >> > > - __attribute__ ((used, section (#set))) = &(symbol) >> > > + static const void *__elf_set_##set##_element_##symbol##__ \ >> > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> > > #else >> > > # define _elf_set_element(set, symbol) \ >> > > - static const void *const __elf_set_##set##_element_##symbol##__ \ >> > > - __attribute__ ((used, section (#set))) = &(symbol) >> > > + static const void *const __elf_set_##set##_element_##symbol##__ \ >> > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> > > #endif >> > > >> > > /* Define SET as a symbol set. This may be required (it is in a.out) to >> > > -- >> > > 2.31.0.291.g576ba9dcdaf-goog >> > > >> > >> > Need gc-sections tests for linkers with and without -z start-stop-gc. >> > >> > -- >> > H.J. >> >> I don't know how to add such a test... It needs to check flush at ext >> time but I cannot find a template in libio/tst-* ... > >You can add a special rule to check for linker output with >--print-gc-sections. I can come up runtime tests. ( https://github.com/MaskRay/glibc/tree/retain) Runtime tests are direct. (Unsure how to test --print-gc-sections with tests-static...) diff --git a/libio/Makefile b/libio/Makefile index 12ce41038f..5e0e7f00cd 100644 --- a/libio/Makefile +++ b/libio/Makefile @@ -195,6 +195,13 @@ ifeq (yes,$(build-shared)) tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ $(objpfx)tst-bz24228-mem.out endif + +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-special += $(objpfx)tst-cleanup-start-stop-gc.out \ + $(objpfx)tst-cleanup-nostart-stop-gc.out +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc endif include ../Rules @@ -224,6 +231,20 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) $(objpfx)tst-wfile-sync.out: $(gen-locales) endif +$(objpfx)tst-cleanup-start-stop-gc.out: $(objpfx)tst-cleanup-start-stop-gc + $< > $@T + grep hello $@T; $(evaluate-test) + rm -f $@T +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-nostart-stop-gc.out: $(objpfx)tst-cleanup-nostart-stop-gc + $< > $@T + grep hello $@T; $(evaluate-test) + rm -f $@T +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ $(common-objpfx)libio/; \ diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c new file mode 100644 index 0000000000..de8130a482 --- /dev/null +++ b/libio/tst-cleanup.c @@ -0,0 +1,14 @@ +#include <stdio.h> +#include <stdlib.h> + +void +hook (void) +{ + puts ("hello"); +} + +int +main (void) +{ + atexit (hook); +} ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-31 4:34 ` Fāng-ruì Sòng @ 2021-03-31 16:17 ` H.J. Lu 2021-03-31 18:09 ` Fāng-ruì Sòng 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-03-31 16:17 UTC (permalink / raw) To: Fāng-ruì Sòng; +Cc: GNU C Library, Florian Weimer On Tue, Mar 30, 2021 at 9:34 PM Fāng-ruì Sòng <maskray@google.com> wrote: > > On 2021-03-30, H.J. Lu wrote: > >On Tue, Mar 30, 2021 at 12:17 PM Fāng-ruì Sòng <maskray@google.com> wrote: > >> > >> On Tue, Mar 30, 2021 at 11:17 AM H.J. Lu <hjl.tools@gmail.com> wrote: > >> > > >> > On Mon, Mar 29, 2021 at 4:24 PM Fangrui Song <maskray@google.com> wrote: > >> > > > >> > > So that text_set_element/data_set_element/bss_set_element defined > >> > > variables will be retained by the linker. > >> > > > >> > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> > > will not be optimized out; 'retain' prevents section garbage collection > >> > > if the linker support SHF_GNU_RETAIN. > >> > > > >> > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> > > identifier name sections to be GCed even if there are live > >> > > __start_/__stop_ references. > >> > > > >> > > Without the change, there are some static linking problems, e.g. > >> > > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> > > stdout is not flushed on exit. > >> > > > >> > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> > > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> > > --- > >> > > Changes in v1 -> v2: > >> > > * Define attribute_used_retain_section > >> > > Changes in v2 -> v3: > >> > > * Use attribute_used_retain instead attribute_used_retain_section > >> > > --- > >> > > config.h.in | 3 +++ > >> > > configure | 23 +++++++++++++++++++++++ > >> > > configure.ac | 16 ++++++++++++++++ > >> > > include/libc-symbols.h | 14 ++++++++++---- > >> > > 4 files changed, 52 insertions(+), 4 deletions(-) > >> > > > >> > > diff --git a/config.h.in b/config.h.in > >> > > index ca1547ae67..95af1ef229 100644 > >> > > --- a/config.h.in > >> > > +++ b/config.h.in > >> > > @@ -187,6 +187,9 @@ > >> > > /* Define if gcc supports attribute ifunc. */ > >> > > #undef HAVE_GCC_IFUNC > >> > > > >> > > +/* Define if gcc supports attribute retain. */ > >> > > +#undef HAVE_GCC_RETAIN > >> > > + > >> > > /* Define if the linker defines __ehdr_start. */ > >> > > #undef HAVE_EHDR_START > >> > > > >> > > diff --git a/configure b/configure > >> > > index fcf43bf7de..6a6b8ac264 100755 > >> > > --- a/configure > >> > > +++ b/configure > >> > > @@ -4105,6 +4105,29 @@ fi > >> > > $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> > > > >> > > > >> > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > >> > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > >> > > +$as_echo_n "checking for gcc attribute retain support... " >&6; } > >> > > +if ${libc_cv_gcc_retain+:} false; then : > >> > > + $as_echo_n "(cached) " >&6 > >> > > +else > >> > > + cat > conftest.c <<EOF > >> > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> > > +EOF > >> > > +libc_cv_gcc_retain=no > >> > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> > > + 2>&5 ; then > >> > > + libc_cv_gcc_retain=yes > >> > > +fi > >> > > +rm -f conftest* > >> > > +fi > >> > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > >> > > +$as_echo "$libc_cv_gcc_retain" >&6; } > >> > > +if test $libc_cv_gcc_retain = yes; then > >> > > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > >> > > + > >> > > +fi > >> > > + > >> > > # Check if gcc warns about alias for function with incompatible types. > >> > > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> > > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> > > diff --git a/configure.ac b/configure.ac > >> > > index fce967f2c2..031b8c3fb3 100644 > >> > > --- a/configure.ac > >> > > +++ b/configure.ac > >> > > @@ -707,6 +707,22 @@ fi > >> > > rm -f conftest*]) > >> > > AC_SUBST(libc_cv_textrel_ifunc) > >> > > > >> > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > >> > > +AC_CACHE_CHECK([for gcc attribute retain support], > >> > > + libc_cv_gcc_retain, [dnl > >> > > +cat > conftest.c <<EOF > >> > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> > > +EOF > >> > > +libc_cv_gcc_retain=no > >> > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> > > + 2>&AS_MESSAGE_LOG_FD ; then > >> > > + libc_cv_gcc_retain=yes > >> > > +fi > >> > > +rm -f conftest*]) > >> > > +if test $libc_cv_gcc_retain = yes; then > >> > > + AC_DEFINE(HAVE_GCC_RETAIN) > >> > > +fi > >> > > + > >> > > # Check if gcc warns about alias for function with incompatible types. > >> > > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> > > libc_cv_gcc_incompatible_alias, [dnl > >> > > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> > > index 546fc26a7b..b311c90f0c 100644 > >> > > --- a/include/libc-symbols.h > >> > > +++ b/include/libc-symbols.h > >> > > @@ -352,6 +352,12 @@ for linking") > >> > > > >> > > */ > >> > > > >> > > +#ifdef HAVE_GCC_RETAIN > >> > > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> > > +#else > >> > > +# define attribute_used_retain __attribute__ ((__used__)) > >> > > +#endif > >> > > + > >> > > /* Symbol set support macros. */ > >> > > > >> > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> > > @@ -367,12 +373,12 @@ for linking") > >> > > /* When building a shared library, make the set section writable, > >> > > because it will need to be relocated at run time anyway. */ > >> > > # define _elf_set_element(set, symbol) \ > >> > > - static const void *__elf_set_##set##_element_##symbol##__ \ > >> > > - __attribute__ ((used, section (#set))) = &(symbol) > >> > > + static const void *__elf_set_##set##_element_##symbol##__ \ > >> > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> > > #else > >> > > # define _elf_set_element(set, symbol) \ > >> > > - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> > > - __attribute__ ((used, section (#set))) = &(symbol) > >> > > + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> > > #endif > >> > > > >> > > /* Define SET as a symbol set. This may be required (it is in a.out) to > >> > > -- > >> > > 2.31.0.291.g576ba9dcdaf-goog > >> > > > >> > > >> > Need gc-sections tests for linkers with and without -z start-stop-gc. > >> > > >> > -- > >> > H.J. > >> > >> I don't know how to add such a test... It needs to check flush at ext > >> time but I cannot find a template in libio/tst-* ... > > > >You can add a special rule to check for linker output with > >--print-gc-sections. > > I can come up runtime tests. ( https://github.com/MaskRay/glibc/tree/retain) > Runtime tests are direct. > (Unsure how to test --print-gc-sections with tests-static...) > > > diff --git a/libio/Makefile b/libio/Makefile > index 12ce41038f..5e0e7f00cd 100644 > --- a/libio/Makefile > +++ b/libio/Makefile > @@ -195,6 +195,13 @@ ifeq (yes,$(build-shared)) > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > $(objpfx)tst-bz24228-mem.out > endif > + > +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-special += $(objpfx)tst-cleanup-start-stop-gc.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc.out > +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc 1. Need to check if linker supports -z start-stop-gc. 2. Need to test with only -Wl,--gc-sections. > endif > > include ../Rules > @@ -224,6 +231,20 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +$(objpfx)tst-cleanup-start-stop-gc.out: $(objpfx)tst-cleanup-start-stop-gc > + $< > $@T > + grep hello $@T; $(evaluate-test) > + rm -f $@T tst-cleanup-start-stop-gc.out isn't generated. You should add a ".exp" file and compare the .out file against it. > +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > + > +$(objpfx)tst-cleanup-nostart-stop-gc.out: $(objpfx)tst-cleanup-nostart-stop-gc > + $< > $@T > + grep hello $@T; $(evaluate-test) > + rm -f $@T > +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > + > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ > diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > new file mode 100644 > index 0000000000..de8130a482 > --- /dev/null > +++ b/libio/tst-cleanup.c > @@ -0,0 +1,14 @@ Missing comments and copyright notice. > +#include <stdio.h> > +#include <stdlib.h> > + > +void > +hook (void) > +{ > + puts ("hello"); > +} > + > +int > +main (void) > +{ > + atexit (hook); > +} -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-31 16:17 ` H.J. Lu @ 2021-03-31 18:09 ` Fāng-ruì Sòng 2021-03-31 18:57 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fāng-ruì Sòng @ 2021-03-31 18:09 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-03-31, H.J. Lu wrote: >On Tue, Mar 30, 2021 at 9:34 PM Fāng-ruì Sòng <maskray@google.com> wrote: >> >> On 2021-03-30, H.J. Lu wrote: >> >On Tue, Mar 30, 2021 at 12:17 PM Fāng-ruì Sòng <maskray@google.com> wrote: >> >> >> >> On Tue, Mar 30, 2021 at 11:17 AM H.J. Lu <hjl.tools@gmail.com> wrote: >> >> > >> >> > On Mon, Mar 29, 2021 at 4:24 PM Fangrui Song <maskray@google.com> wrote: >> >> > > >> >> > > So that text_set_element/data_set_element/bss_set_element defined >> >> > > variables will be retained by the linker. >> >> > > >> >> > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> >> > > will not be optimized out; 'retain' prevents section garbage collection >> >> > > if the linker support SHF_GNU_RETAIN. >> >> > > >> >> > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> >> > > identifier name sections to be GCed even if there are live >> >> > > __start_/__stop_ references. >> >> > > >> >> > > Without the change, there are some static linking problems, e.g. >> >> > > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> >> > > stdout is not flushed on exit. >> >> > > >> >> > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> >> > > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> >> > > --- >> >> > > Changes in v1 -> v2: >> >> > > * Define attribute_used_retain_section >> >> > > Changes in v2 -> v3: >> >> > > * Use attribute_used_retain instead attribute_used_retain_section >> >> > > --- >> >> > > config.h.in | 3 +++ >> >> > > configure | 23 +++++++++++++++++++++++ >> >> > > configure.ac | 16 ++++++++++++++++ >> >> > > include/libc-symbols.h | 14 ++++++++++---- >> >> > > 4 files changed, 52 insertions(+), 4 deletions(-) >> >> > > >> >> > > diff --git a/config.h.in b/config.h.in >> >> > > index ca1547ae67..95af1ef229 100644 >> >> > > --- a/config.h.in >> >> > > +++ b/config.h.in >> >> > > @@ -187,6 +187,9 @@ >> >> > > /* Define if gcc supports attribute ifunc. */ >> >> > > #undef HAVE_GCC_IFUNC >> >> > > >> >> > > +/* Define if gcc supports attribute retain. */ >> >> > > +#undef HAVE_GCC_RETAIN >> >> > > + >> >> > > /* Define if the linker defines __ehdr_start. */ >> >> > > #undef HAVE_EHDR_START >> >> > > >> >> > > diff --git a/configure b/configure >> >> > > index fcf43bf7de..6a6b8ac264 100755 >> >> > > --- a/configure >> >> > > +++ b/configure >> >> > > @@ -4105,6 +4105,29 @@ fi >> >> > > $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> > > >> >> > > >> >> > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. >> >> > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 >> >> > > +$as_echo_n "checking for gcc attribute retain support... " >&6; } >> >> > > +if ${libc_cv_gcc_retain+:} false; then : >> >> > > + $as_echo_n "(cached) " >&6 >> >> > > +else >> >> > > + cat > conftest.c <<EOF >> >> > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> > > +EOF >> >> > > +libc_cv_gcc_retain=no >> >> > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> > > + 2>&5 ; then >> >> > > + libc_cv_gcc_retain=yes >> >> > > +fi >> >> > > +rm -f conftest* >> >> > > +fi >> >> > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 >> >> > > +$as_echo "$libc_cv_gcc_retain" >&6; } >> >> > > +if test $libc_cv_gcc_retain = yes; then >> >> > > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h >> >> > > + >> >> > > +fi >> >> > > + >> >> > > # Check if gcc warns about alias for function with incompatible types. >> >> > > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> > > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> > > diff --git a/configure.ac b/configure.ac >> >> > > index fce967f2c2..031b8c3fb3 100644 >> >> > > --- a/configure.ac >> >> > > +++ b/configure.ac >> >> > > @@ -707,6 +707,22 @@ fi >> >> > > rm -f conftest*]) >> >> > > AC_SUBST(libc_cv_textrel_ifunc) >> >> > > >> >> > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. >> >> > > +AC_CACHE_CHECK([for gcc attribute retain support], >> >> > > + libc_cv_gcc_retain, [dnl >> >> > > +cat > conftest.c <<EOF >> >> > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> > > +EOF >> >> > > +libc_cv_gcc_retain=no >> >> > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> > > + 2>&AS_MESSAGE_LOG_FD ; then >> >> > > + libc_cv_gcc_retain=yes >> >> > > +fi >> >> > > +rm -f conftest*]) >> >> > > +if test $libc_cv_gcc_retain = yes; then >> >> > > + AC_DEFINE(HAVE_GCC_RETAIN) >> >> > > +fi >> >> > > + >> >> > > # Check if gcc warns about alias for function with incompatible types. >> >> > > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> > > libc_cv_gcc_incompatible_alias, [dnl >> >> > > diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> > > index 546fc26a7b..b311c90f0c 100644 >> >> > > --- a/include/libc-symbols.h >> >> > > +++ b/include/libc-symbols.h >> >> > > @@ -352,6 +352,12 @@ for linking") >> >> > > >> >> > > */ >> >> > > >> >> > > +#ifdef HAVE_GCC_RETAIN >> >> > > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> > > +#else >> >> > > +# define attribute_used_retain __attribute__ ((__used__)) >> >> > > +#endif >> >> > > + >> >> > > /* Symbol set support macros. */ >> >> > > >> >> > > /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> > > @@ -367,12 +373,12 @@ for linking") >> >> > > /* When building a shared library, make the set section writable, >> >> > > because it will need to be relocated at run time anyway. */ >> >> > > # define _elf_set_element(set, symbol) \ >> >> > > - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> > > - __attribute__ ((used, section (#set))) = &(symbol) >> >> > > + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> > > #else >> >> > > # define _elf_set_element(set, symbol) \ >> >> > > - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> > > - __attribute__ ((used, section (#set))) = &(symbol) >> >> > > + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> > > #endif >> >> > > >> >> > > /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> > > -- >> >> > > 2.31.0.291.g576ba9dcdaf-goog >> >> > > >> >> > >> >> > Need gc-sections tests for linkers with and without -z start-stop-gc. >> >> > >> >> > -- >> >> > H.J. >> >> >> >> I don't know how to add such a test... It needs to check flush at ext >> >> time but I cannot find a template in libio/tst-* ... >> > >> >You can add a special rule to check for linker output with >> >--print-gc-sections. >> >> I can come up runtime tests. ( https://github.com/MaskRay/glibc/tree/retain) >> Runtime tests are direct. >> (Unsure how to test --print-gc-sections with tests-static...) >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> index 12ce41038f..5e0e7f00cd 100644 >> --- a/libio/Makefile >> +++ b/libio/Makefile >> @@ -195,6 +195,13 @@ ifeq (yes,$(build-shared)) >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> $(objpfx)tst-bz24228-mem.out >> endif >> + >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc.out >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > >1. Need to check if linker supports -z start-stop-gc. This seems difficult to do with Makefile... Second, do we need to check it? ld warns instead of errors for an unknown -z option, so not checking it may be fine. (GNU ld warns even with --fatal-warnings.) >2. Need to test with only -Wl,--gc-sections. OK, removed -z,nostart-stop-gc -LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections >> endif >> >> include ../Rules >> @@ -224,6 +231,20 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> endif >> >> +$(objpfx)tst-cleanup-start-stop-gc.out: $(objpfx)tst-cleanup-start-stop-gc >> + $< > $@T >> + grep hello $@T; $(evaluate-test) >> + rm -f $@T > >tst-cleanup-start-stop-gc.out isn't generated. You should add a ".exp" file >and compare the .out file against it. Thanks for the tip. Added tst-cleanup.exp with the content "hello\n" (see the usage below). > >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> +$(objpfx)tst-cleanup-nostart-stop-gc.out: $(objpfx)tst-cleanup-nostart-stop-gc >> + $< > $@T >> + grep hello $@T; $(evaluate-test) >> + rm -f $@T >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> $(common-objpfx)libio/; \ >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> new file mode 100644 >> index 0000000000..de8130a482 >> --- /dev/null >> +++ b/libio/tst-cleanup.c >> @@ -0,0 +1,14 @@ > >Missing comments and copyright notice. OK. I find that many tst* files don't have a copyright notice.. Added. >> +#include <stdio.h> >> +#include <stdlib.h> >> + >> +void >> +hook (void) >> +{ >> + puts ("hello"); >> +} >> + >> +int >> +main (void) >> +{ >> + atexit (hook); >> +} diff --git a/libio/Makefile b/libio/Makefile index 12ce41038f..472a1e064c 100644 --- a/libio/Makefile +++ b/libio/Makefile @@ -195,6 +195,13 @@ ifeq (yes,$(build-shared)) tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ $(objpfx)tst-bz24228-mem.out endif + +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc endif include ../Rules @@ -224,6 +231,18 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) $(objpfx)tst-wfile-sync.out: $(gen-locales) endif +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ $(common-objpfx)libio/; \ diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c new file mode 100644 index 0000000000..7f0a34a91e --- /dev/null +++ b/libio/tst-cleanup.c @@ -0,0 +1,33 @@ +/* Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* Test that stdout is flushed after atexit callbacks were run. */ + +#include <stdio.h> +#include <stdlib.h> + +void +hook (void) +{ + puts ("hello"); +} + +int +main (void) +{ + atexit (hook); +} ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v3] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-31 18:09 ` Fāng-ruì Sòng @ 2021-03-31 18:57 ` H.J. Lu 2021-03-31 19:39 ` [PATCH v4] " Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-03-31 18:57 UTC (permalink / raw) To: Fāng-ruì Sòng; +Cc: GNU C Library, Florian Weimer On Wed, Mar 31, 2021 at 11:09 AM Fāng-ruì Sòng <maskray@google.com> wrote: > > > On 2021-03-31, H.J. Lu wrote: > >On Tue, Mar 30, 2021 at 9:34 PM Fāng-ruì Sòng <maskray@google.com> wrote: > >> > >> On 2021-03-30, H.J. Lu wrote: > >> >On Tue, Mar 30, 2021 at 12:17 PM Fāng-ruì Sòng <maskray@google.com> wrote: > >> >> > >> >> On Tue, Mar 30, 2021 at 11:17 AM H.J. Lu <hjl.tools@gmail.com> wrote: > >> >> > > >> >> > On Mon, Mar 29, 2021 at 4:24 PM Fangrui Song <maskray@google.com> wrote: > >> >> > > > >> >> > > So that text_set_element/data_set_element/bss_set_element defined > >> >> > > variables will be retained by the linker. > >> >> > > > >> >> > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> >> > > will not be optimized out; 'retain' prevents section garbage collection > >> >> > > if the linker support SHF_GNU_RETAIN. > >> >> > > > >> >> > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> >> > > identifier name sections to be GCed even if there are live > >> >> > > __start_/__stop_ references. > >> >> > > > >> >> > > Without the change, there are some static linking problems, e.g. > >> >> > > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> >> > > stdout is not flushed on exit. > >> >> > > > >> >> > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> >> > > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> >> > > --- > >> >> > > Changes in v1 -> v2: > >> >> > > * Define attribute_used_retain_section > >> >> > > Changes in v2 -> v3: > >> >> > > * Use attribute_used_retain instead attribute_used_retain_section > >> >> > > --- > >> >> > > config.h.in | 3 +++ > >> >> > > configure | 23 +++++++++++++++++++++++ > >> >> > > configure.ac | 16 ++++++++++++++++ > >> >> > > include/libc-symbols.h | 14 ++++++++++---- > >> >> > > 4 files changed, 52 insertions(+), 4 deletions(-) > >> >> > > > >> >> > > diff --git a/config.h.in b/config.h.in > >> >> > > index ca1547ae67..95af1ef229 100644 > >> >> > > --- a/config.h.in > >> >> > > +++ b/config.h.in > >> >> > > @@ -187,6 +187,9 @@ > >> >> > > /* Define if gcc supports attribute ifunc. */ > >> >> > > #undef HAVE_GCC_IFUNC > >> >> > > > >> >> > > +/* Define if gcc supports attribute retain. */ > >> >> > > +#undef HAVE_GCC_RETAIN > >> >> > > + > >> >> > > /* Define if the linker defines __ehdr_start. */ > >> >> > > #undef HAVE_EHDR_START > >> >> > > > >> >> > > diff --git a/configure b/configure > >> >> > > index fcf43bf7de..6a6b8ac264 100755 > >> >> > > --- a/configure > >> >> > > +++ b/configure > >> >> > > @@ -4105,6 +4105,29 @@ fi > >> >> > > $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> > > > >> >> > > > >> >> > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > >> >> > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > >> >> > > +$as_echo_n "checking for gcc attribute retain support... " >&6; } > >> >> > > +if ${libc_cv_gcc_retain+:} false; then : > >> >> > > + $as_echo_n "(cached) " >&6 > >> >> > > +else > >> >> > > + cat > conftest.c <<EOF > >> >> > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> > > +EOF > >> >> > > +libc_cv_gcc_retain=no > >> >> > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> > > + 2>&5 ; then > >> >> > > + libc_cv_gcc_retain=yes > >> >> > > +fi > >> >> > > +rm -f conftest* > >> >> > > +fi > >> >> > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > >> >> > > +$as_echo "$libc_cv_gcc_retain" >&6; } > >> >> > > +if test $libc_cv_gcc_retain = yes; then > >> >> > > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > >> >> > > + > >> >> > > +fi > >> >> > > + > >> >> > > # Check if gcc warns about alias for function with incompatible types. > >> >> > > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> > > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> > > diff --git a/configure.ac b/configure.ac > >> >> > > index fce967f2c2..031b8c3fb3 100644 > >> >> > > --- a/configure.ac > >> >> > > +++ b/configure.ac > >> >> > > @@ -707,6 +707,22 @@ fi > >> >> > > rm -f conftest*]) > >> >> > > AC_SUBST(libc_cv_textrel_ifunc) > >> >> > > > >> >> > > +# Check if gcc supports attribute ifunc as it is used in libc_ifunc macro. > >> >> > > +AC_CACHE_CHECK([for gcc attribute retain support], > >> >> > > + libc_cv_gcc_retain, [dnl > >> >> > > +cat > conftest.c <<EOF > >> >> > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> > > +EOF > >> >> > > +libc_cv_gcc_retain=no > >> >> > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> > > + 2>&AS_MESSAGE_LOG_FD ; then > >> >> > > + libc_cv_gcc_retain=yes > >> >> > > +fi > >> >> > > +rm -f conftest*]) > >> >> > > +if test $libc_cv_gcc_retain = yes; then > >> >> > > + AC_DEFINE(HAVE_GCC_RETAIN) > >> >> > > +fi > >> >> > > + > >> >> > > # Check if gcc warns about alias for function with incompatible types. > >> >> > > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> > > libc_cv_gcc_incompatible_alias, [dnl > >> >> > > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> > > index 546fc26a7b..b311c90f0c 100644 > >> >> > > --- a/include/libc-symbols.h > >> >> > > +++ b/include/libc-symbols.h > >> >> > > @@ -352,6 +352,12 @@ for linking") > >> >> > > > >> >> > > */ > >> >> > > > >> >> > > +#ifdef HAVE_GCC_RETAIN > >> >> > > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> > > +#else > >> >> > > +# define attribute_used_retain __attribute__ ((__used__)) > >> >> > > +#endif > >> >> > > + > >> >> > > /* Symbol set support macros. */ > >> >> > > > >> >> > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> > > @@ -367,12 +373,12 @@ for linking") > >> >> > > /* When building a shared library, make the set section writable, > >> >> > > because it will need to be relocated at run time anyway. */ > >> >> > > # define _elf_set_element(set, symbol) \ > >> >> > > - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> > > - __attribute__ ((used, section (#set))) = &(symbol) > >> >> > > + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> > > #else > >> >> > > # define _elf_set_element(set, symbol) \ > >> >> > > - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> > > - __attribute__ ((used, section (#set))) = &(symbol) > >> >> > > + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> > > #endif > >> >> > > > >> >> > > /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> > > -- > >> >> > > 2.31.0.291.g576ba9dcdaf-goog > >> >> > > > >> >> > > >> >> > Need gc-sections tests for linkers with and without -z start-stop-gc. > >> >> > > >> >> > -- > >> >> > H.J. > >> >> > >> >> I don't know how to add such a test... It needs to check flush at ext > >> >> time but I cannot find a template in libio/tst-* ... > >> > > >> >You can add a special rule to check for linker output with > >> >--print-gc-sections. > >> > >> I can come up runtime tests. ( https://github.com/MaskRay/glibc/tree/retain) > >> Runtime tests are direct. > >> (Unsure how to test --print-gc-sections with tests-static...) > >> > >> > >> diff --git a/libio/Makefile b/libio/Makefile > >> index 12ce41038f..5e0e7f00cd 100644 > >> --- a/libio/Makefile > >> +++ b/libio/Makefile > >> @@ -195,6 +195,13 @@ ifeq (yes,$(build-shared)) > >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> $(objpfx)tst-bz24228-mem.out > >> endif > >> + > >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc.out > >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > > > >1. Need to check if linker supports -z start-stop-gc. > > This seems difficult to do with Makefile... Second, do we need to check it? > ld warns instead of errors for an unknown -z option, so not checking it > may be fine. (GNU ld warns even with --fatal-warnings.) Please use LIBC_LINKER_FEATURE and LIBC_CONFIG_VAR to detect and check linker features. > >2. Need to test with only -Wl,--gc-sections. > > OK, removed -z,nostart-stop-gc We need all 3 tests with -Wl,--gc-sections. > -LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections > > >> endif > >> > >> include ../Rules > >> @@ -224,6 +231,20 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> endif > >> > >> +$(objpfx)tst-cleanup-start-stop-gc.out: $(objpfx)tst-cleanup-start-stop-gc > >> + $< > $@T > >> + grep hello $@T; $(evaluate-test) > >> + rm -f $@T > > > >tst-cleanup-start-stop-gc.out isn't generated. You should add a ".exp" file > >and compare the .out file against it. > > Thanks for the tip. Added tst-cleanup.exp with the content "hello\n" (see the usage below). > > > >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> + > >> +$(objpfx)tst-cleanup-nostart-stop-gc.out: $(objpfx)tst-cleanup-nostart-stop-gc > >> + $< > $@T > >> + grep hello $@T; $(evaluate-test) > >> + rm -f $@T > >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> + > >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> $(common-objpfx)libio/; \ > >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > >> new file mode 100644 > >> index 0000000000..de8130a482 > >> --- /dev/null > >> +++ b/libio/tst-cleanup.c > >> @@ -0,0 +1,14 @@ > > > >Missing comments and copyright notice. > > OK. I find that many tst* files don't have a copyright notice.. > Added. > > >> +#include <stdio.h> > >> +#include <stdlib.h> > >> + > >> +void > >> +hook (void) > >> +{ > >> + puts ("hello"); > >> +} > >> + > >> +int > >> +main (void) > >> +{ > >> + atexit (hook); > >> +} > > > diff --git a/libio/Makefile b/libio/Makefile > index 12ce41038f..472a1e064c 100644 > --- a/libio/Makefile > +++ b/libio/Makefile > @@ -195,6 +195,13 @@ ifeq (yes,$(build-shared)) > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > $(objpfx)tst-bz24228-mem.out > endif > + > +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > endif > > include ../Rules > @@ -224,6 +231,18 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > + > +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > + > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ > diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > new file mode 100644 > index 0000000000..7f0a34a91e > --- /dev/null > +++ b/libio/tst-cleanup.c > @@ -0,0 +1,33 @@ > +/* Copyright (C) 2021 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + <https://www.gnu.org/licenses/>. */ > + > +/* Test that stdout is flushed after atexit callbacks were run. */ > + > +#include <stdio.h> > +#include <stdlib.h> > + > +void > +hook (void) > +{ > + puts ("hello"); > +} > + > +int > +main (void) > +{ > + atexit (hook); > +} -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v4] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-31 18:57 ` H.J. Lu @ 2021-03-31 19:39 ` Fangrui Song 2021-03-31 23:38 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-03-31 19:39 UTC (permalink / raw) To: libc-alpha, Florian Weimer, H . J . Lu ; +Cc: Fangrui Song So that text_set_element/data_set_element/bss_set_element defined variables will be retained by the linker. Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable will not be optimized out; 'retain' prevents section garbage collection if the linker support SHF_GNU_RETAIN. GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C identifier name sections to be GCed even if there are live __start_/__stop_ references. Without the change, there are some static linking problems, e.g. _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so stdout is not flushed on exit. Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). --- Changes in v1 -> v2: * Define attribute_used_retain_section Changes in v2 -> v3: * Use attribute_used_retain instead attribute_used_retain_section Changes in v3 -> v4: * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests --- config.h.in | 3 +++ configure | 58 ++++++++++++++++++++++++++++++++++++++++++ configure.ac | 20 +++++++++++++++ include/libc-symbols.h | 14 +++++++--- libio/Makefile | 32 +++++++++++++++++++++++ libio/tst-cleanup.c | 33 ++++++++++++++++++++++++ libio/tst-cleanup.exp | 1 + 7 files changed, 157 insertions(+), 4 deletions(-) create mode 100644 libio/tst-cleanup.c create mode 100644 libio/tst-cleanup.exp diff --git a/config.h.in b/config.h.in index ca1547ae67..95af1ef229 100644 --- a/config.h.in +++ b/config.h.in @@ -187,6 +187,9 @@ /* Define if gcc supports attribute ifunc. */ #undef HAVE_GCC_IFUNC +/* Define if gcc supports attribute retain. */ +#undef HAVE_GCC_RETAIN + /* Define if the linker defines __ehdr_start. */ #undef HAVE_EHDR_START diff --git a/configure b/configure index fcf43bf7de..fa86348342 100755 --- a/configure +++ b/configure @@ -626,6 +626,7 @@ fno_unit_at_a_time libc_cv_has_glob_dat libc_cv_hashstyle libc_cv_fpie +libc_cv_z_start_stop_gc libc_cv_z_execstack libc_cv_z_combreloc ASFLAGS_config @@ -4105,6 +4106,29 @@ fi $as_echo "$libc_cv_textrel_ifunc" >&6; } +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 +$as_echo_n "checking for gcc attribute retain support... " >&6; } +if ${libc_cv_gcc_retain+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gcc_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ + 2>&5 ; then + libc_cv_gcc_retain=yes +fi +rm -f conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 +$as_echo "$libc_cv_gcc_retain" >&6; } +if test $libc_cv_gcc_retain = yes; then + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h + +fi + # Check if gcc warns about alias for function with incompatible types. { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } @@ -5871,6 +5895,40 @@ fi $as_echo "$libc_linker_feature" >&6; } +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } +libc_linker_feature=no +if test x"$gnu_ld" = x"yes"; then + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` + if test -n "$libc_linker_check"; then + cat > conftest.c <<EOF +int _start (void) { return 42; } +EOF + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp + -Wl,-z,start-stop-gc -nostdlib -nostartfiles + -fPIC -shared -o conftest.so conftest.c + 1>&5' + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 + (eval $ac_try) 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; }; } + then + libc_linker_feature=yes + fi + rm -f conftest* + fi +fi +if test $libc_linker_feature = yes; then + libc_cv_z_start_stop_gc=yes +else + libc_cv_z_start_stop_gc=no +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 +$as_echo "$libc_linker_feature" >&6; } +config_vars="$config_vars +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } libc_linker_feature=no diff --git a/configure.ac b/configure.ac index fce967f2c2..4e2907da92 100644 --- a/configure.ac +++ b/configure.ac @@ -707,6 +707,22 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_textrel_ifunc) +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. +AC_CACHE_CHECK([for gcc attribute retain support], + libc_cv_gcc_retain, [dnl +cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gcc_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ + 2>&AS_MESSAGE_LOG_FD ; then + libc_cv_gcc_retain=yes +fi +rm -f conftest*]) +if test $libc_cv_gcc_retain = yes; then + AC_DEFINE(HAVE_GCC_RETAIN) +fi + # Check if gcc warns about alias for function with incompatible types. AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], libc_cv_gcc_incompatible_alias, [dnl @@ -1317,6 +1333,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) AC_SUBST(libc_cv_z_execstack) +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) + LIBC_LINKER_FEATURE([--no-dynamic-linker], [-Wl,--no-dynamic-linker], [libc_cv_no_dynamic_linker=yes], diff --git a/include/libc-symbols.h b/include/libc-symbols.h index 546fc26a7b..b311c90f0c 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -352,6 +352,12 @@ for linking") \f */ +#ifdef HAVE_GCC_RETAIN +# define attribute_used_retain __attribute__ ((__used__, __retain__)) +#else +# define attribute_used_retain __attribute__ ((__used__)) +#endif + /* Symbol set support macros. */ /* Make SYMBOL, which is in the text segment, an element of SET. */ @@ -367,12 +373,12 @@ for linking") /* When building a shared library, make the set section writable, because it will need to be relocated at run time anyway. */ # define _elf_set_element(set, symbol) \ - static const void *__elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *__elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #else # define _elf_set_element(set, symbol) \ - static const void *const __elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *const __elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #endif /* Define SET as a symbol set. This may be required (it is in a.out) to diff --git a/libio/Makefile b/libio/Makefile index 12ce41038f..439d22e057 100644 --- a/libio/Makefile +++ b/libio/Makefile @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ $(objpfx)tst-bz24228-mem.out endif + +tests += tst-cleanup-default +tests-static += tst-cleanup-default +tests-special += $(objpfx)tst-cleanup-default-cmp.out +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections + +ifeq ($(have-z-start-stop-gc),yes) +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc +endif endif include ../Rules @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) $(objpfx)tst-wfile-sync.out: $(gen-locales) endif +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-default.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ $(common-objpfx)libio/; \ diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c new file mode 100644 index 0000000000..7f0a34a91e --- /dev/null +++ b/libio/tst-cleanup.c @@ -0,0 +1,33 @@ +/* Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* Test that stdout is flushed after atexit callbacks were run. */ + +#include <stdio.h> +#include <stdlib.h> + +void +hook (void) +{ + puts ("hello"); +} + +int +main (void) +{ + atexit (hook); +} diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp new file mode 100644 index 0000000000..ce01362503 --- /dev/null +++ b/libio/tst-cleanup.exp @@ -0,0 +1 @@ +hello -- 2.31.0.291.g576ba9dcdaf-goog ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v4] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-31 19:39 ` [PATCH v4] " Fangrui Song @ 2021-03-31 23:38 ` H.J. Lu 2021-04-01 0:02 ` Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-03-31 23:38 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Wed, Mar 31, 2021 at 12:39 PM Fangrui Song <maskray@google.com> wrote: > > So that text_set_element/data_set_element/bss_set_element defined > variables will be retained by the linker. > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > will not be optimized out; 'retain' prevents section garbage collection > if the linker support SHF_GNU_RETAIN. > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > identifier name sections to be GCed even if there are live > __start_/__stop_ references. > > Without the change, there are some static linking problems, e.g. > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > stdout is not flushed on exit. > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > --- > Changes in v1 -> v2: > * Define attribute_used_retain_section > Changes in v2 -> v3: > * Use attribute_used_retain instead attribute_used_retain_section > Changes in v3 -> v4: > * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > --- > config.h.in | 3 +++ > configure | 58 ++++++++++++++++++++++++++++++++++++++++++ > configure.ac | 20 +++++++++++++++ > include/libc-symbols.h | 14 +++++++--- > libio/Makefile | 32 +++++++++++++++++++++++ > libio/tst-cleanup.c | 33 ++++++++++++++++++++++++ > libio/tst-cleanup.exp | 1 + > 7 files changed, 157 insertions(+), 4 deletions(-) > create mode 100644 libio/tst-cleanup.c > create mode 100644 libio/tst-cleanup.exp > > diff --git a/config.h.in b/config.h.in > index ca1547ae67..95af1ef229 100644 > --- a/config.h.in > +++ b/config.h.in > @@ -187,6 +187,9 @@ > /* Define if gcc supports attribute ifunc. */ > #undef HAVE_GCC_IFUNC > > +/* Define if gcc supports attribute retain. */ > +#undef HAVE_GCC_RETAIN > + > /* Define if the linker defines __ehdr_start. */ > #undef HAVE_EHDR_START > > diff --git a/configure b/configure > index fcf43bf7de..fa86348342 100755 > --- a/configure > +++ b/configure > @@ -626,6 +626,7 @@ fno_unit_at_a_time > libc_cv_has_glob_dat > libc_cv_hashstyle > libc_cv_fpie > +libc_cv_z_start_stop_gc > libc_cv_z_execstack > libc_cv_z_combreloc > ASFLAGS_config > @@ -4105,6 +4106,29 @@ fi > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > +$as_echo_n "checking for gcc attribute retain support... " >&6; } > +if ${libc_cv_gcc_retain+:} false; then : > + $as_echo_n "(cached) " >&6 > +else > + cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gcc_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > + 2>&5 ; then > + libc_cv_gcc_retain=yes > +fi > +rm -f conftest* > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > +$as_echo "$libc_cv_gcc_retain" >&6; } > +if test $libc_cv_gcc_retain = yes; then > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > + > +fi > + > # Check if gcc warns about alias for function with incompatible types. > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > @@ -5871,6 +5895,40 @@ fi > $as_echo "$libc_linker_feature" >&6; } > > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > +libc_linker_feature=no > +if test x"$gnu_ld" = x"yes"; then > + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > + if test -n "$libc_linker_check"; then > + cat > conftest.c <<EOF > +int _start (void) { return 42; } > +EOF > + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > + -fPIC -shared -o conftest.so conftest.c > + 1>&5' > + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > + (eval $ac_try) 2>&5 > + ac_status=$? > + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > + test $ac_status = 0; }; } > + then > + libc_linker_feature=yes > + fi > + rm -f conftest* > + fi > +fi > +if test $libc_linker_feature = yes; then > + libc_cv_z_start_stop_gc=yes > +else > + libc_cv_z_start_stop_gc=no > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > +$as_echo "$libc_linker_feature" >&6; } > +config_vars="$config_vars > +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > + > { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > libc_linker_feature=no > diff --git a/configure.ac b/configure.ac > index fce967f2c2..4e2907da92 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -707,6 +707,22 @@ fi > rm -f conftest*]) > AC_SUBST(libc_cv_textrel_ifunc) > > +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. > +AC_CACHE_CHECK([for gcc attribute retain support], > + libc_cv_gcc_retain, [dnl > +cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gcc_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > + 2>&AS_MESSAGE_LOG_FD ; then > + libc_cv_gcc_retain=yes > +fi > +rm -f conftest*]) > +if test $libc_cv_gcc_retain = yes; then > + AC_DEFINE(HAVE_GCC_RETAIN) > +fi > + > # Check if gcc warns about alias for function with incompatible types. > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > libc_cv_gcc_incompatible_alias, [dnl > @@ -1317,6 +1333,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > AC_SUBST(libc_cv_z_execstack) > > +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > + > LIBC_LINKER_FEATURE([--no-dynamic-linker], > [-Wl,--no-dynamic-linker], > [libc_cv_no_dynamic_linker=yes], > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > index 546fc26a7b..b311c90f0c 100644 > --- a/include/libc-symbols.h > +++ b/include/libc-symbols.h > @@ -352,6 +352,12 @@ for linking") > > */ > > +#ifdef HAVE_GCC_RETAIN > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > +#else > +# define attribute_used_retain __attribute__ ((__used__)) > +#endif > + > /* Symbol set support macros. */ > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > @@ -367,12 +373,12 @@ for linking") > /* When building a shared library, make the set section writable, > because it will need to be relocated at run time anyway. */ > # define _elf_set_element(set, symbol) \ > - static const void *__elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *__elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #else > # define _elf_set_element(set, symbol) \ > - static const void *const __elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #endif > > /* Define SET as a symbol set. This may be required (it is in a.out) to > diff --git a/libio/Makefile b/libio/Makefile > index 12ce41038f..439d22e057 100644 > --- a/libio/Makefile > +++ b/libio/Makefile > @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > $(objpfx)tst-bz24228-mem.out > endif > + > +tests += tst-cleanup-default > +tests-static += tst-cleanup-default > +tests-special += $(objpfx)tst-cleanup-default-cmp.out > +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > + > +ifeq ($(have-z-start-stop-gc),yes) > +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc Won't this test fail if linker supports -z start-stop-gc and GCC doesn't support retain attribute? > +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > +endif > endif > > include ../Rules > @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > + $(compile.c) -o $@ > + > +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > + > +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > + > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ > diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > new file mode 100644 > index 0000000000..7f0a34a91e > --- /dev/null > +++ b/libio/tst-cleanup.c > @@ -0,0 +1,33 @@ > +/* Copyright (C) 2021 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + <https://www.gnu.org/licenses/>. */ > + > +/* Test that stdout is flushed after atexit callbacks were run. */ > + > +#include <stdio.h> > +#include <stdlib.h> > + > +void > +hook (void) > +{ > + puts ("hello"); > +} > + > +int > +main (void) > +{ > + atexit (hook); > +} > diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > new file mode 100644 > index 0000000000..ce01362503 > --- /dev/null > +++ b/libio/tst-cleanup.exp > @@ -0,0 +1 @@ > +hello > -- > 2.31.0.291.g576ba9dcdaf-goog > -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v4] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-03-31 23:38 ` H.J. Lu @ 2021-04-01 0:02 ` Fangrui Song 2021-04-01 1:00 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-04-01 0:02 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-03-31, H.J. Lu wrote: >On Wed, Mar 31, 2021 at 12:39 PM Fangrui Song <maskray@google.com> wrote: >> >> So that text_set_element/data_set_element/bss_set_element defined >> variables will be retained by the linker. >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> will not be optimized out; 'retain' prevents section garbage collection >> if the linker support SHF_GNU_RETAIN. >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> identifier name sections to be GCed even if there are live >> __start_/__stop_ references. >> >> Without the change, there are some static linking problems, e.g. >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> stdout is not flushed on exit. >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> --- >> Changes in v1 -> v2: >> * Define attribute_used_retain_section >> Changes in v2 -> v3: >> * Use attribute_used_retain instead attribute_used_retain_section >> Changes in v3 -> v4: >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests >> --- >> config.h.in | 3 +++ >> configure | 58 ++++++++++++++++++++++++++++++++++++++++++ >> configure.ac | 20 +++++++++++++++ >> include/libc-symbols.h | 14 +++++++--- >> libio/Makefile | 32 +++++++++++++++++++++++ >> libio/tst-cleanup.c | 33 ++++++++++++++++++++++++ >> libio/tst-cleanup.exp | 1 + >> 7 files changed, 157 insertions(+), 4 deletions(-) >> create mode 100644 libio/tst-cleanup.c >> create mode 100644 libio/tst-cleanup.exp >> >> diff --git a/config.h.in b/config.h.in >> index ca1547ae67..95af1ef229 100644 >> --- a/config.h.in >> +++ b/config.h.in >> @@ -187,6 +187,9 @@ >> /* Define if gcc supports attribute ifunc. */ >> #undef HAVE_GCC_IFUNC >> >> +/* Define if gcc supports attribute retain. */ >> +#undef HAVE_GCC_RETAIN >> + >> /* Define if the linker defines __ehdr_start. */ >> #undef HAVE_EHDR_START >> >> diff --git a/configure b/configure >> index fcf43bf7de..fa86348342 100755 >> --- a/configure >> +++ b/configure >> @@ -626,6 +626,7 @@ fno_unit_at_a_time >> libc_cv_has_glob_dat >> libc_cv_hashstyle >> libc_cv_fpie >> +libc_cv_z_start_stop_gc >> libc_cv_z_execstack >> libc_cv_z_combreloc >> ASFLAGS_config >> @@ -4105,6 +4106,29 @@ fi >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 >> +$as_echo_n "checking for gcc attribute retain support... " >&6; } >> +if ${libc_cv_gcc_retain+:} false; then : >> + $as_echo_n "(cached) " >&6 >> +else >> + cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gcc_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> + 2>&5 ; then >> + libc_cv_gcc_retain=yes >> +fi >> +rm -f conftest* >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 >> +$as_echo "$libc_cv_gcc_retain" >&6; } >> +if test $libc_cv_gcc_retain = yes; then >> + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h >> + >> +fi >> + >> # Check if gcc warns about alias for function with incompatible types. >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> @@ -5871,6 +5895,40 @@ fi >> $as_echo "$libc_linker_feature" >&6; } >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> +libc_linker_feature=no >> +if test x"$gnu_ld" = x"yes"; then >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> + if test -n "$libc_linker_check"; then >> + cat > conftest.c <<EOF >> +int _start (void) { return 42; } >> +EOF >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> + -fPIC -shared -o conftest.so conftest.c >> + 1>&5' >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> + (eval $ac_try) 2>&5 >> + ac_status=$? >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> + test $ac_status = 0; }; } >> + then >> + libc_linker_feature=yes >> + fi >> + rm -f conftest* >> + fi >> +fi >> +if test $libc_linker_feature = yes; then >> + libc_cv_z_start_stop_gc=yes >> +else >> + libc_cv_z_start_stop_gc=no >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> +$as_echo "$libc_linker_feature" >&6; } >> +config_vars="$config_vars >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> + >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> libc_linker_feature=no >> diff --git a/configure.ac b/configure.ac >> index fce967f2c2..4e2907da92 100644 >> --- a/configure.ac >> +++ b/configure.ac >> @@ -707,6 +707,22 @@ fi >> rm -f conftest*]) >> AC_SUBST(libc_cv_textrel_ifunc) >> >> +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. >> +AC_CACHE_CHECK([for gcc attribute retain support], >> + libc_cv_gcc_retain, [dnl >> +cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gcc_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> + 2>&AS_MESSAGE_LOG_FD ; then >> + libc_cv_gcc_retain=yes >> +fi >> +rm -f conftest*]) >> +if test $libc_cv_gcc_retain = yes; then >> + AC_DEFINE(HAVE_GCC_RETAIN) >> +fi >> + >> # Check if gcc warns about alias for function with incompatible types. >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> libc_cv_gcc_incompatible_alias, [dnl >> @@ -1317,6 +1333,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> AC_SUBST(libc_cv_z_execstack) >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> + >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> [-Wl,--no-dynamic-linker], >> [libc_cv_no_dynamic_linker=yes], >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> index 546fc26a7b..b311c90f0c 100644 >> --- a/include/libc-symbols.h >> +++ b/include/libc-symbols.h >> @@ -352,6 +352,12 @@ for linking") >> >> */ >> >> +#ifdef HAVE_GCC_RETAIN >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> +#else >> +# define attribute_used_retain __attribute__ ((__used__)) >> +#endif >> + >> /* Symbol set support macros. */ >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> @@ -367,12 +373,12 @@ for linking") >> /* When building a shared library, make the set section writable, >> because it will need to be relocated at run time anyway. */ >> # define _elf_set_element(set, symbol) \ >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #else >> # define _elf_set_element(set, symbol) \ >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #endif >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> diff --git a/libio/Makefile b/libio/Makefile >> index 12ce41038f..439d22e057 100644 >> --- a/libio/Makefile >> +++ b/libio/Makefile >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> $(objpfx)tst-bz24228-mem.out >> endif >> + >> +tests += tst-cleanup-default >> +tests-static += tst-cleanup-default >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> + >> +ifeq ($(have-z-start-stop-gc),yes) >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >Won't this test fail if linker supports -z start-stop-gc and GCC doesn't support >retain attribute? Yes, but that doesn't happen in practice. If ld supports -z start-stop-gc, the GNU as should be new and the GCC should support 'retain'. But perhaps it is good to prevent the issue, I can change +ifeq ($(have-z-start-stop-gc),yes) to +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) and add a LIBC_CONFIG_VAR in configure.ac. >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc >> +endif >> endif >> >> include ../Rules >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> endif >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> $(common-objpfx)libio/; \ >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> new file mode 100644 >> index 0000000000..7f0a34a91e >> --- /dev/null >> +++ b/libio/tst-cleanup.c >> @@ -0,0 +1,33 @@ >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> + This file is part of the GNU C Library. >> + >> + The GNU C Library is free software; you can redistribute it and/or >> + modify it under the terms of the GNU Lesser General Public >> + License as published by the Free Software Foundation; either >> + version 2.1 of the License, or (at your option) any later version. >> + >> + The GNU C Library is distributed in the hope that it will be useful, >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> + Lesser General Public License for more details. >> + >> + You should have received a copy of the GNU Lesser General Public >> + License along with the GNU C Library; if not, see >> + <https://www.gnu.org/licenses/>. */ >> + >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> + >> +#include <stdio.h> >> +#include <stdlib.h> >> + >> +void >> +hook (void) >> +{ >> + puts ("hello"); >> +} >> + >> +int >> +main (void) >> +{ >> + atexit (hook); >> +} >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> new file mode 100644 >> index 0000000000..ce01362503 >> --- /dev/null >> +++ b/libio/tst-cleanup.exp >> @@ -0,0 +1 @@ >> +hello >> -- >> 2.31.0.291.g576ba9dcdaf-goog >> > > >-- >H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v4] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-01 0:02 ` Fangrui Song @ 2021-04-01 1:00 ` H.J. Lu 2021-04-01 1:06 ` [PATCH v5] " Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-04-01 1:00 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Wed, Mar 31, 2021 at 5:02 PM Fangrui Song <maskray@google.com> wrote: > > On 2021-03-31, H.J. Lu wrote: > >On Wed, Mar 31, 2021 at 12:39 PM Fangrui Song <maskray@google.com> wrote: > >> > >> So that text_set_element/data_set_element/bss_set_element defined > >> variables will be retained by the linker. > >> > >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> will not be optimized out; 'retain' prevents section garbage collection > >> if the linker support SHF_GNU_RETAIN. > >> > >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> identifier name sections to be GCed even if there are live > >> __start_/__stop_ references. > >> > >> Without the change, there are some static linking problems, e.g. > >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> stdout is not flushed on exit. > >> > >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> --- > >> Changes in v1 -> v2: > >> * Define attribute_used_retain_section > >> Changes in v2 -> v3: > >> * Use attribute_used_retain instead attribute_used_retain_section > >> Changes in v3 -> v4: > >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> --- > >> config.h.in | 3 +++ > >> configure | 58 ++++++++++++++++++++++++++++++++++++++++++ > >> configure.ac | 20 +++++++++++++++ > >> include/libc-symbols.h | 14 +++++++--- > >> libio/Makefile | 32 +++++++++++++++++++++++ > >> libio/tst-cleanup.c | 33 ++++++++++++++++++++++++ > >> libio/tst-cleanup.exp | 1 + > >> 7 files changed, 157 insertions(+), 4 deletions(-) > >> create mode 100644 libio/tst-cleanup.c > >> create mode 100644 libio/tst-cleanup.exp > >> > >> diff --git a/config.h.in b/config.h.in > >> index ca1547ae67..95af1ef229 100644 > >> --- a/config.h.in > >> +++ b/config.h.in > >> @@ -187,6 +187,9 @@ > >> /* Define if gcc supports attribute ifunc. */ > >> #undef HAVE_GCC_IFUNC > >> > >> +/* Define if gcc supports attribute retain. */ > >> +#undef HAVE_GCC_RETAIN > >> + > >> /* Define if the linker defines __ehdr_start. */ > >> #undef HAVE_EHDR_START > >> > >> diff --git a/configure b/configure > >> index fcf43bf7de..fa86348342 100755 > >> --- a/configure > >> +++ b/configure > >> @@ -626,6 +626,7 @@ fno_unit_at_a_time > >> libc_cv_has_glob_dat > >> libc_cv_hashstyle > >> libc_cv_fpie > >> +libc_cv_z_start_stop_gc > >> libc_cv_z_execstack > >> libc_cv_z_combreloc > >> ASFLAGS_config > >> @@ -4105,6 +4106,29 @@ fi > >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> > >> > >> +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > >> +$as_echo_n "checking for gcc attribute retain support... " >&6; } > >> +if ${libc_cv_gcc_retain+:} false; then : > >> + $as_echo_n "(cached) " >&6 > >> +else > >> + cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gcc_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> + 2>&5 ; then > >> + libc_cv_gcc_retain=yes > >> +fi > >> +rm -f conftest* > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > >> +$as_echo "$libc_cv_gcc_retain" >&6; } > >> +if test $libc_cv_gcc_retain = yes; then > >> + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > >> + > >> +fi > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> @@ -5871,6 +5895,40 @@ fi > >> $as_echo "$libc_linker_feature" >&6; } > >> > >> > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> +libc_linker_feature=no > >> +if test x"$gnu_ld" = x"yes"; then > >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> + if test -n "$libc_linker_check"; then > >> + cat > conftest.c <<EOF > >> +int _start (void) { return 42; } > >> +EOF > >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> + -fPIC -shared -o conftest.so conftest.c > >> + 1>&5' > >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> + (eval $ac_try) 2>&5 > >> + ac_status=$? > >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> + test $ac_status = 0; }; } > >> + then > >> + libc_linker_feature=yes > >> + fi > >> + rm -f conftest* > >> + fi > >> +fi > >> +if test $libc_linker_feature = yes; then > >> + libc_cv_z_start_stop_gc=yes > >> +else > >> + libc_cv_z_start_stop_gc=no > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> +$as_echo "$libc_linker_feature" >&6; } > >> +config_vars="$config_vars > >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> + > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> libc_linker_feature=no > >> diff --git a/configure.ac b/configure.ac > >> index fce967f2c2..4e2907da92 100644 > >> --- a/configure.ac > >> +++ b/configure.ac > >> @@ -707,6 +707,22 @@ fi > >> rm -f conftest*]) > >> AC_SUBST(libc_cv_textrel_ifunc) > >> > >> +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. > >> +AC_CACHE_CHECK([for gcc attribute retain support], > >> + libc_cv_gcc_retain, [dnl > >> +cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gcc_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> + 2>&AS_MESSAGE_LOG_FD ; then > >> + libc_cv_gcc_retain=yes > >> +fi > >> +rm -f conftest*]) > >> +if test $libc_cv_gcc_retain = yes; then > >> + AC_DEFINE(HAVE_GCC_RETAIN) > >> +fi > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> libc_cv_gcc_incompatible_alias, [dnl > >> @@ -1317,6 +1333,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> AC_SUBST(libc_cv_z_execstack) > >> > >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> + > >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> [-Wl,--no-dynamic-linker], > >> [libc_cv_no_dynamic_linker=yes], > >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> index 546fc26a7b..b311c90f0c 100644 > >> --- a/include/libc-symbols.h > >> +++ b/include/libc-symbols.h > >> @@ -352,6 +352,12 @@ for linking") > >> > >> */ > >> > >> +#ifdef HAVE_GCC_RETAIN > >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> +#else > >> +# define attribute_used_retain __attribute__ ((__used__)) > >> +#endif > >> + > >> /* Symbol set support macros. */ > >> > >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> @@ -367,12 +373,12 @@ for linking") > >> /* When building a shared library, make the set section writable, > >> because it will need to be relocated at run time anyway. */ > >> # define _elf_set_element(set, symbol) \ > >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #else > >> # define _elf_set_element(set, symbol) \ > >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #endif > >> > >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> diff --git a/libio/Makefile b/libio/Makefile > >> index 12ce41038f..439d22e057 100644 > >> --- a/libio/Makefile > >> +++ b/libio/Makefile > >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> $(objpfx)tst-bz24228-mem.out > >> endif > >> + > >> +tests += tst-cleanup-default > >> +tests-static += tst-cleanup-default > >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> + > >> +ifeq ($(have-z-start-stop-gc),yes) > >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > > > >Won't this test fail if linker supports -z start-stop-gc and GCC doesn't support > >retain attribute? > > Yes, but that doesn't happen in practice. If ld supports -z start-stop-gc, > the GNU as should be new and the GCC should support 'retain'. I am using GCC 10 and binutils 2.37. > But perhaps it is good to prevent the issue, I can change > > +ifeq ($(have-z-start-stop-gc),yes) > > to > > +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > > and add a LIBC_CONFIG_VAR in configure.ac. > Yes, please. Thanks. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-01 1:00 ` H.J. Lu @ 2021-04-01 1:06 ` Fangrui Song 2021-04-01 12:52 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-04-01 1:06 UTC (permalink / raw) To: libc-alpha, Florian Weimer, H . J . Lu ; +Cc: Fangrui Song So that text_set_element/data_set_element/bss_set_element defined variables will be retained by the linker. Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable will not be optimized out; 'retain' prevents section garbage collection if the linker support SHF_GNU_RETAIN. GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C identifier name sections to be GCed even if there are live __start_/__stop_ references. Without the change, there are some static linking problems, e.g. _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so stdout is not flushed on exit. Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). --- Changes in v1 -> v2: * Define attribute_used_retain_section Changes in v2 -> v3: * Use attribute_used_retain instead attribute_used_retain_section Changes in v3 -> v4: * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests Changes in v4 -> v5: * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported * Rename *gcc_retain* to *gnu_retain* --- config.h.in | 3 +++ configure | 59 ++++++++++++++++++++++++++++++++++++++++++ configure.ac | 21 +++++++++++++++ include/libc-symbols.h | 14 +++++++--- libio/Makefile | 32 +++++++++++++++++++++++ libio/tst-cleanup.c | 33 +++++++++++++++++++++++ libio/tst-cleanup.exp | 1 + 7 files changed, 159 insertions(+), 4 deletions(-) create mode 100644 libio/tst-cleanup.c create mode 100644 libio/tst-cleanup.exp diff --git a/config.h.in b/config.h.in index ca1547ae67..96a08c7757 100644 --- a/config.h.in +++ b/config.h.in @@ -187,6 +187,9 @@ /* Define if gcc supports attribute ifunc. */ #undef HAVE_GCC_IFUNC +/* Define if CC supports attribute retain. */ +#undef HAVE_GNU_RETAIN + /* Define if the linker defines __ehdr_start. */ #undef HAVE_EHDR_START diff --git a/configure b/configure index fcf43bf7de..e64b7f8efe 100755 --- a/configure +++ b/configure @@ -4105,6 +4105,31 @@ fi $as_echo "$libc_cv_textrel_ifunc" >&6; } +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 +$as_echo_n "checking for GNU attribute retain support... " >&6; } +if ${libc_cv_gnu_retain+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gnu_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ + 2>&5 ; then + libc_cv_gnu_retain=yes +fi +rm -f conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 +$as_echo "$libc_cv_gnu_retain" >&6; } +if test $libc_cv_gnu_retain = yes; then + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h + +fi +config_vars="$config_vars +have-gnu-retain = $libc_cv_gnu_retain" + # Check if gcc warns about alias for function with incompatible types. { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } @@ -5871,6 +5896,40 @@ fi $as_echo "$libc_linker_feature" >&6; } +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } +libc_linker_feature=no +if test x"$gnu_ld" = x"yes"; then + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` + if test -n "$libc_linker_check"; then + cat > conftest.c <<EOF +int _start (void) { return 42; } +EOF + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp + -Wl,-z,start-stop-gc -nostdlib -nostartfiles + -fPIC -shared -o conftest.so conftest.c + 1>&5' + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 + (eval $ac_try) 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; }; } + then + libc_linker_feature=yes + fi + rm -f conftest* + fi +fi +if test $libc_linker_feature = yes; then + libc_cv_z_start_stop_gc=yes +else + libc_cv_z_start_stop_gc=no +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 +$as_echo "$libc_linker_feature" >&6; } +config_vars="$config_vars +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } libc_linker_feature=no diff --git a/configure.ac b/configure.ac index fce967f2c2..cc47e56e82 100644 --- a/configure.ac +++ b/configure.ac @@ -707,6 +707,23 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_textrel_ifunc) +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. +AC_CACHE_CHECK([for GNU attribute retain support], + libc_cv_gnu_retain, [dnl +cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gnu_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ + 2>&AS_MESSAGE_LOG_FD ; then + libc_cv_gnu_retain=yes +fi +rm -f conftest*]) +if test $libc_cv_gnu_retain = yes; then + AC_DEFINE(HAVE_GNU_RETAIN) +fi +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) + # Check if gcc warns about alias for function with incompatible types. AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], libc_cv_gcc_incompatible_alias, [dnl @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) AC_SUBST(libc_cv_z_execstack) +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) + LIBC_LINKER_FEATURE([--no-dynamic-linker], [-Wl,--no-dynamic-linker], [libc_cv_no_dynamic_linker=yes], diff --git a/include/libc-symbols.h b/include/libc-symbols.h index 546fc26a7b..127ea656c2 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -352,6 +352,12 @@ for linking") \f */ +#ifdef HAVE_GNU_RETAIN +# define attribute_used_retain __attribute__ ((__used__, __retain__)) +#else +# define attribute_used_retain __attribute__ ((__used__)) +#endif + /* Symbol set support macros. */ /* Make SYMBOL, which is in the text segment, an element of SET. */ @@ -367,12 +373,12 @@ for linking") /* When building a shared library, make the set section writable, because it will need to be relocated at run time anyway. */ # define _elf_set_element(set, symbol) \ - static const void *__elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *__elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #else # define _elf_set_element(set, symbol) \ - static const void *const __elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *const __elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #endif /* Define SET as a symbol set. This may be required (it is in a.out) to diff --git a/libio/Makefile b/libio/Makefile index 12ce41038f..c9c232ebc2 100644 --- a/libio/Makefile +++ b/libio/Makefile @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ $(objpfx)tst-bz24228-mem.out endif + +tests += tst-cleanup-default +tests-static += tst-cleanup-default +tests-special += $(objpfx)tst-cleanup-default-cmp.out +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections + +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc +endif endif include ../Rules @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) $(objpfx)tst-wfile-sync.out: $(gen-locales) endif +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-default.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ $(common-objpfx)libio/; \ diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c new file mode 100644 index 0000000000..7f0a34a91e --- /dev/null +++ b/libio/tst-cleanup.c @@ -0,0 +1,33 @@ +/* Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* Test that stdout is flushed after atexit callbacks were run. */ + +#include <stdio.h> +#include <stdlib.h> + +void +hook (void) +{ + puts ("hello"); +} + +int +main (void) +{ + atexit (hook); +} diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp new file mode 100644 index 0000000000..ce01362503 --- /dev/null +++ b/libio/tst-cleanup.exp @@ -0,0 +1 @@ +hello -- 2.31.0.291.g576ba9dcdaf-goog ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-01 1:06 ` [PATCH v5] " Fangrui Song @ 2021-04-01 12:52 ` H.J. Lu 2021-04-02 3:23 ` Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-04-01 12:52 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > > So that text_set_element/data_set_element/bss_set_element defined > variables will be retained by the linker. > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > will not be optimized out; 'retain' prevents section garbage collection > if the linker support SHF_GNU_RETAIN. > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > identifier name sections to be GCed even if there are live > __start_/__stop_ references. > > Without the change, there are some static linking problems, e.g. > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > stdout is not flushed on exit. > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > --- > Changes in v1 -> v2: > * Define attribute_used_retain_section > Changes in v2 -> v3: > * Use attribute_used_retain instead attribute_used_retain_section > Changes in v3 -> v4: > * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > Changes in v4 -> v5: > * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > * Rename *gcc_retain* to *gnu_retain* > --- > config.h.in | 3 +++ > configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > configure.ac | 21 +++++++++++++++ > include/libc-symbols.h | 14 +++++++--- > libio/Makefile | 32 +++++++++++++++++++++++ > libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > libio/tst-cleanup.exp | 1 + > 7 files changed, 159 insertions(+), 4 deletions(-) > create mode 100644 libio/tst-cleanup.c > create mode 100644 libio/tst-cleanup.exp > > diff --git a/config.h.in b/config.h.in > index ca1547ae67..96a08c7757 100644 > --- a/config.h.in > +++ b/config.h.in > @@ -187,6 +187,9 @@ > /* Define if gcc supports attribute ifunc. */ > #undef HAVE_GCC_IFUNC > > +/* Define if CC supports attribute retain. */ > +#undef HAVE_GNU_RETAIN > + > /* Define if the linker defines __ehdr_start. */ > #undef HAVE_EHDR_START > > diff --git a/configure b/configure > index fcf43bf7de..e64b7f8efe 100755 > --- a/configure > +++ b/configure > @@ -4105,6 +4105,31 @@ fi > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > +$as_echo_n "checking for GNU attribute retain support... " >&6; } > +if ${libc_cv_gnu_retain+:} false; then : > + $as_echo_n "(cached) " >&6 > +else > + cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gnu_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > + 2>&5 ; then > + libc_cv_gnu_retain=yes > +fi > +rm -f conftest* > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > +$as_echo "$libc_cv_gnu_retain" >&6; } > +if test $libc_cv_gnu_retain = yes; then > + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > + > +fi > +config_vars="$config_vars > +have-gnu-retain = $libc_cv_gnu_retain" > + > # Check if gcc warns about alias for function with incompatible types. > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > @@ -5871,6 +5896,40 @@ fi > $as_echo "$libc_linker_feature" >&6; } > > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > +libc_linker_feature=no > +if test x"$gnu_ld" = x"yes"; then > + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > + if test -n "$libc_linker_check"; then > + cat > conftest.c <<EOF > +int _start (void) { return 42; } > +EOF > + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > + -fPIC -shared -o conftest.so conftest.c > + 1>&5' > + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > + (eval $ac_try) 2>&5 > + ac_status=$? > + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > + test $ac_status = 0; }; } > + then > + libc_linker_feature=yes > + fi > + rm -f conftest* > + fi > +fi > +if test $libc_linker_feature = yes; then > + libc_cv_z_start_stop_gc=yes > +else > + libc_cv_z_start_stop_gc=no > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > +$as_echo "$libc_linker_feature" >&6; } > +config_vars="$config_vars > +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > + > { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > libc_linker_feature=no > diff --git a/configure.ac b/configure.ac > index fce967f2c2..cc47e56e82 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -707,6 +707,23 @@ fi > rm -f conftest*]) > AC_SUBST(libc_cv_textrel_ifunc) > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > +AC_CACHE_CHECK([for GNU attribute retain support], > + libc_cv_gnu_retain, [dnl > +cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gnu_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > + 2>&AS_MESSAGE_LOG_FD ; then > + libc_cv_gnu_retain=yes > +fi > +rm -f conftest*]) > +if test $libc_cv_gnu_retain = yes; then > + AC_DEFINE(HAVE_GNU_RETAIN) > +fi > +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > + > # Check if gcc warns about alias for function with incompatible types. > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > libc_cv_gcc_incompatible_alias, [dnl > @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > AC_SUBST(libc_cv_z_execstack) > > +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > + > LIBC_LINKER_FEATURE([--no-dynamic-linker], > [-Wl,--no-dynamic-linker], > [libc_cv_no_dynamic_linker=yes], > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > index 546fc26a7b..127ea656c2 100644 > --- a/include/libc-symbols.h > +++ b/include/libc-symbols.h > @@ -352,6 +352,12 @@ for linking") > > */ > > +#ifdef HAVE_GNU_RETAIN > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > +#else > +# define attribute_used_retain __attribute__ ((__used__)) > +#endif > + > /* Symbol set support macros. */ > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > @@ -367,12 +373,12 @@ for linking") > /* When building a shared library, make the set section writable, > because it will need to be relocated at run time anyway. */ > # define _elf_set_element(set, symbol) \ > - static const void *__elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *__elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #else > # define _elf_set_element(set, symbol) \ > - static const void *const __elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #endif > > /* Define SET as a symbol set. This may be required (it is in a.out) to > diff --git a/libio/Makefile b/libio/Makefile > index 12ce41038f..c9c232ebc2 100644 > --- a/libio/Makefile > +++ b/libio/Makefile > @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > $(objpfx)tst-bz24228-mem.out > endif > + > +tests += tst-cleanup-default > +tests-static += tst-cleanup-default > +tests-special += $(objpfx)tst-cleanup-default-cmp.out Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > + > +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out Same here. > +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > +endif > endif > > include ../Rules > @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > + $(compile.c) -o $@ > + > +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > + > +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ > diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > new file mode 100644 > index 0000000000..7f0a34a91e > --- /dev/null > +++ b/libio/tst-cleanup.c > @@ -0,0 +1,33 @@ Please add a comment saying that test --gc-sections. > +/* Copyright (C) 2021 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + <https://www.gnu.org/licenses/>. */ > + > +/* Test that stdout is flushed after atexit callbacks were run. */ > + > +#include <stdio.h> > +#include <stdlib.h> > + > +void > +hook (void) > +{ > + puts ("hello"); > +} > + > +int > +main (void) > +{ > + atexit (hook); > +} > diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > new file mode 100644 > index 0000000000..ce01362503 > --- /dev/null > +++ b/libio/tst-cleanup.exp > @@ -0,0 +1 @@ > +hello > -- > 2.31.0.291.g576ba9dcdaf-goog > -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-01 12:52 ` H.J. Lu @ 2021-04-02 3:23 ` Fangrui Song 2021-04-02 14:14 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-04-02 3:23 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-04-01, H.J. Lu wrote: >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: >> >> So that text_set_element/data_set_element/bss_set_element defined >> variables will be retained by the linker. >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> will not be optimized out; 'retain' prevents section garbage collection >> if the linker support SHF_GNU_RETAIN. >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> identifier name sections to be GCed even if there are live >> __start_/__stop_ references. >> >> Without the change, there are some static linking problems, e.g. >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> stdout is not flushed on exit. >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> --- >> Changes in v1 -> v2: >> * Define attribute_used_retain_section >> Changes in v2 -> v3: >> * Use attribute_used_retain instead attribute_used_retain_section >> Changes in v3 -> v4: >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests >> Changes in v4 -> v5: >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported >> * Rename *gcc_retain* to *gnu_retain* >> --- >> config.h.in | 3 +++ >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ >> configure.ac | 21 +++++++++++++++ >> include/libc-symbols.h | 14 +++++++--- >> libio/Makefile | 32 +++++++++++++++++++++++ >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ >> libio/tst-cleanup.exp | 1 + >> 7 files changed, 159 insertions(+), 4 deletions(-) >> create mode 100644 libio/tst-cleanup.c >> create mode 100644 libio/tst-cleanup.exp >> >> diff --git a/config.h.in b/config.h.in >> index ca1547ae67..96a08c7757 100644 >> --- a/config.h.in >> +++ b/config.h.in >> @@ -187,6 +187,9 @@ >> /* Define if gcc supports attribute ifunc. */ >> #undef HAVE_GCC_IFUNC >> >> +/* Define if CC supports attribute retain. */ >> +#undef HAVE_GNU_RETAIN >> + >> /* Define if the linker defines __ehdr_start. */ >> #undef HAVE_EHDR_START >> >> diff --git a/configure b/configure >> index fcf43bf7de..e64b7f8efe 100755 >> --- a/configure >> +++ b/configure >> @@ -4105,6 +4105,31 @@ fi >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> +if ${libc_cv_gnu_retain+:} false; then : >> + $as_echo_n "(cached) " >&6 >> +else >> + cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gnu_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> + 2>&5 ; then >> + libc_cv_gnu_retain=yes >> +fi >> +rm -f conftest* >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> +if test $libc_cv_gnu_retain = yes; then >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> + >> +fi >> +config_vars="$config_vars >> +have-gnu-retain = $libc_cv_gnu_retain" >> + >> # Check if gcc warns about alias for function with incompatible types. >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> @@ -5871,6 +5896,40 @@ fi >> $as_echo "$libc_linker_feature" >&6; } >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> +libc_linker_feature=no >> +if test x"$gnu_ld" = x"yes"; then >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> + if test -n "$libc_linker_check"; then >> + cat > conftest.c <<EOF >> +int _start (void) { return 42; } >> +EOF >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> + -fPIC -shared -o conftest.so conftest.c >> + 1>&5' >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> + (eval $ac_try) 2>&5 >> + ac_status=$? >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> + test $ac_status = 0; }; } >> + then >> + libc_linker_feature=yes >> + fi >> + rm -f conftest* >> + fi >> +fi >> +if test $libc_linker_feature = yes; then >> + libc_cv_z_start_stop_gc=yes >> +else >> + libc_cv_z_start_stop_gc=no >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> +$as_echo "$libc_linker_feature" >&6; } >> +config_vars="$config_vars >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> + >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> libc_linker_feature=no >> diff --git a/configure.ac b/configure.ac >> index fce967f2c2..cc47e56e82 100644 >> --- a/configure.ac >> +++ b/configure.ac >> @@ -707,6 +707,23 @@ fi >> rm -f conftest*]) >> AC_SUBST(libc_cv_textrel_ifunc) >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> +AC_CACHE_CHECK([for GNU attribute retain support], >> + libc_cv_gnu_retain, [dnl >> +cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gnu_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> + 2>&AS_MESSAGE_LOG_FD ; then >> + libc_cv_gnu_retain=yes >> +fi >> +rm -f conftest*]) >> +if test $libc_cv_gnu_retain = yes; then >> + AC_DEFINE(HAVE_GNU_RETAIN) >> +fi >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> + >> # Check if gcc warns about alias for function with incompatible types. >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> libc_cv_gcc_incompatible_alias, [dnl >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> AC_SUBST(libc_cv_z_execstack) >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> + >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> [-Wl,--no-dynamic-linker], >> [libc_cv_no_dynamic_linker=yes], >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> index 546fc26a7b..127ea656c2 100644 >> --- a/include/libc-symbols.h >> +++ b/include/libc-symbols.h >> @@ -352,6 +352,12 @@ for linking") >> >> */ >> >> +#ifdef HAVE_GNU_RETAIN >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> +#else >> +# define attribute_used_retain __attribute__ ((__used__)) >> +#endif >> + >> /* Symbol set support macros. */ >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> @@ -367,12 +373,12 @@ for linking") >> /* When building a shared library, make the set section writable, >> because it will need to be relocated at run time anyway. */ >> # define _elf_set_element(set, symbol) \ >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #else >> # define _elf_set_element(set, symbol) \ >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #endif >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> diff --git a/libio/Makefile b/libio/Makefile >> index 12ce41038f..c9c232ebc2 100644 >> --- a/libio/Makefile >> +++ b/libio/Makefile >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> $(objpfx)tst-bz24228-mem.out >> endif >> + >> +tests += tst-cleanup-default >> +tests-static += tst-cleanup-default >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. Added. >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> + >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >Same here. Added. >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc >> +endif >> endif >> >> include ../Rules >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> endif >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> $(common-objpfx)libio/; \ >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> new file mode 100644 >> index 0000000000..7f0a34a91e >> --- /dev/null >> +++ b/libio/tst-cleanup.c >> @@ -0,0 +1,33 @@ > >Please add a comment saying that test --gc-sections. OK, added. >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> + This file is part of the GNU C Library. >> + >> + The GNU C Library is free software; you can redistribute it and/or >> + modify it under the terms of the GNU Lesser General Public >> + License as published by the Free Software Foundation; either >> + version 2.1 of the License, or (at your option) any later version. >> + >> + The GNU C Library is distributed in the hope that it will be useful, >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> + Lesser General Public License for more details. >> + >> + You should have received a copy of the GNU Lesser General Public >> + License along with the GNU C Library; if not, see >> + <https://www.gnu.org/licenses/>. */ >> + >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> + >> +#include <stdio.h> >> +#include <stdlib.h> >> + >> +void >> +hook (void) >> +{ >> + puts ("hello"); >> +} >> + >> +int >> +main (void) >> +{ >> + atexit (hook); >> +} >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> new file mode 100644 >> index 0000000000..ce01362503 >> --- /dev/null >> +++ b/libio/tst-cleanup.exp >> @@ -0,0 +1 @@ >> +hello >> -- >> 2.31.0.291.g576ba9dcdaf-goog >> > diff --git a/config.h.in b/config.h.in index ca1547ae67..96a08c7757 100644 --- a/config.h.in +++ b/config.h.in @@ -187,6 +187,9 @@ /* Define if gcc supports attribute ifunc. */ #undef HAVE_GCC_IFUNC +/* Define if CC supports attribute retain. */ +#undef HAVE_GNU_RETAIN + /* Define if the linker defines __ehdr_start. */ #undef HAVE_EHDR_START diff --git a/configure b/configure index fcf43bf7de..e64b7f8efe 100755 --- a/configure +++ b/configure @@ -4105,6 +4105,31 @@ fi $as_echo "$libc_cv_textrel_ifunc" >&6; } +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 +$as_echo_n "checking for GNU attribute retain support... " >&6; } +if ${libc_cv_gnu_retain+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gnu_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ + 2>&5 ; then + libc_cv_gnu_retain=yes +fi +rm -f conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 +$as_echo "$libc_cv_gnu_retain" >&6; } +if test $libc_cv_gnu_retain = yes; then + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h + +fi +config_vars="$config_vars +have-gnu-retain = $libc_cv_gnu_retain" + # Check if gcc warns about alias for function with incompatible types. { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } @@ -5871,6 +5896,40 @@ fi $as_echo "$libc_linker_feature" >&6; } +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } +libc_linker_feature=no +if test x"$gnu_ld" = x"yes"; then + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` + if test -n "$libc_linker_check"; then + cat > conftest.c <<EOF +int _start (void) { return 42; } +EOF + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp + -Wl,-z,start-stop-gc -nostdlib -nostartfiles + -fPIC -shared -o conftest.so conftest.c + 1>&5' + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 + (eval $ac_try) 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; }; } + then + libc_linker_feature=yes + fi + rm -f conftest* + fi +fi +if test $libc_linker_feature = yes; then + libc_cv_z_start_stop_gc=yes +else + libc_cv_z_start_stop_gc=no +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 +$as_echo "$libc_linker_feature" >&6; } +config_vars="$config_vars +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } libc_linker_feature=no diff --git a/configure.ac b/configure.ac index fce967f2c2..cc47e56e82 100644 --- a/configure.ac +++ b/configure.ac @@ -707,6 +707,23 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_textrel_ifunc) +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. +AC_CACHE_CHECK([for GNU attribute retain support], + libc_cv_gnu_retain, [dnl +cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gnu_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ + 2>&AS_MESSAGE_LOG_FD ; then + libc_cv_gnu_retain=yes +fi +rm -f conftest*]) +if test $libc_cv_gnu_retain = yes; then + AC_DEFINE(HAVE_GNU_RETAIN) +fi +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) + # Check if gcc warns about alias for function with incompatible types. AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], libc_cv_gcc_incompatible_alias, [dnl @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) AC_SUBST(libc_cv_z_execstack) +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) + LIBC_LINKER_FEATURE([--no-dynamic-linker], [-Wl,--no-dynamic-linker], [libc_cv_no_dynamic_linker=yes], diff --git a/include/libc-symbols.h b/include/libc-symbols.h index 546fc26a7b..127ea656c2 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -352,6 +352,12 @@ for linking") \f */ +#ifdef HAVE_GNU_RETAIN +# define attribute_used_retain __attribute__ ((__used__, __retain__)) +#else +# define attribute_used_retain __attribute__ ((__used__)) +#endif + /* Symbol set support macros. */ /* Make SYMBOL, which is in the text segment, an element of SET. */ @@ -367,12 +373,12 @@ for linking") /* When building a shared library, make the set section writable, because it will need to be relocated at run time anyway. */ # define _elf_set_element(set, symbol) \ - static const void *__elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *__elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #else # define _elf_set_element(set, symbol) \ - static const void *const __elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *const __elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #endif /* Define SET as a symbol set. This may be required (it is in a.out) to diff --git a/libio/Makefile b/libio/Makefile index 12ce41038f..ad0d53bb49 100644 --- a/libio/Makefile +++ b/libio/Makefile @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ $(objpfx)tst-bz24228-mem.out endif + +tests += tst-cleanup-default tst-cleanup-default-static +tests-static += tst-cleanup-default-static +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections + +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc +endif endif include ../Rules @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) $(objpfx)tst-wfile-sync.out: $(gen-locales) endif +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-default.o: tst-cleanup.c + $(compile.c) -o $@ +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-nostart-stop-gc-static.o: tst-cleanup.c + $(compile.c) -o $@ + $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ $(common-objpfx)libio/; \ diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c new file mode 100644 index 0000000000..837feac164 --- /dev/null +++ b/libio/tst-cleanup.c @@ -0,0 +1,34 @@ +/* Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* Test that stdout is flushed after atexit callbacks were run, even if the + * executable is linked with --gc-sections. */ + +#include <stdio.h> +#include <stdlib.h> + +void +hook (void) +{ + puts ("hello"); +} + +int +main (void) +{ + atexit (hook); +} diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp new file mode 100644 index 0000000000..ce01362503 --- /dev/null +++ b/libio/tst-cleanup.exp @@ -0,0 +1 @@ +hello -- 2.31.0.208.g409f899ff0-goog ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-02 3:23 ` Fangrui Song @ 2021-04-02 14:14 ` H.J. Lu 2021-04-02 17:09 ` Fangrui Song 2021-04-03 18:02 ` Fangrui Song 0 siblings, 2 replies; 40+ messages in thread From: H.J. Lu @ 2021-04-02 14:14 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: > > On 2021-04-01, H.J. Lu wrote: > >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > >> > >> So that text_set_element/data_set_element/bss_set_element defined > >> variables will be retained by the linker. > >> > >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> will not be optimized out; 'retain' prevents section garbage collection > >> if the linker support SHF_GNU_RETAIN. > >> > >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> identifier name sections to be GCed even if there are live > >> __start_/__stop_ references. > >> > >> Without the change, there are some static linking problems, e.g. > >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> stdout is not flushed on exit. > >> > >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> --- > >> Changes in v1 -> v2: > >> * Define attribute_used_retain_section > >> Changes in v2 -> v3: > >> * Use attribute_used_retain instead attribute_used_retain_section > >> Changes in v3 -> v4: > >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> Changes in v4 -> v5: > >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > >> * Rename *gcc_retain* to *gnu_retain* > >> --- > >> config.h.in | 3 +++ > >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > >> configure.ac | 21 +++++++++++++++ > >> include/libc-symbols.h | 14 +++++++--- > >> libio/Makefile | 32 +++++++++++++++++++++++ > >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > >> libio/tst-cleanup.exp | 1 + > >> 7 files changed, 159 insertions(+), 4 deletions(-) > >> create mode 100644 libio/tst-cleanup.c > >> create mode 100644 libio/tst-cleanup.exp > >> > >> diff --git a/config.h.in b/config.h.in > >> index ca1547ae67..96a08c7757 100644 > >> --- a/config.h.in > >> +++ b/config.h.in > >> @@ -187,6 +187,9 @@ > >> /* Define if gcc supports attribute ifunc. */ > >> #undef HAVE_GCC_IFUNC > >> > >> +/* Define if CC supports attribute retain. */ > >> +#undef HAVE_GNU_RETAIN > >> + > >> /* Define if the linker defines __ehdr_start. */ > >> #undef HAVE_EHDR_START > >> > >> diff --git a/configure b/configure > >> index fcf43bf7de..e64b7f8efe 100755 > >> --- a/configure > >> +++ b/configure > >> @@ -4105,6 +4105,31 @@ fi > >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> > >> > >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> +if ${libc_cv_gnu_retain+:} false; then : > >> + $as_echo_n "(cached) " >&6 > >> +else > >> + cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gnu_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> + 2>&5 ; then > >> + libc_cv_gnu_retain=yes > >> +fi > >> +rm -f conftest* > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> +if test $libc_cv_gnu_retain = yes; then > >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> + > >> +fi > >> +config_vars="$config_vars > >> +have-gnu-retain = $libc_cv_gnu_retain" > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> @@ -5871,6 +5896,40 @@ fi > >> $as_echo "$libc_linker_feature" >&6; } > >> > >> > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> +libc_linker_feature=no > >> +if test x"$gnu_ld" = x"yes"; then > >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> + if test -n "$libc_linker_check"; then > >> + cat > conftest.c <<EOF > >> +int _start (void) { return 42; } > >> +EOF > >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> + -fPIC -shared -o conftest.so conftest.c > >> + 1>&5' > >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> + (eval $ac_try) 2>&5 > >> + ac_status=$? > >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> + test $ac_status = 0; }; } > >> + then > >> + libc_linker_feature=yes > >> + fi > >> + rm -f conftest* > >> + fi > >> +fi > >> +if test $libc_linker_feature = yes; then > >> + libc_cv_z_start_stop_gc=yes > >> +else > >> + libc_cv_z_start_stop_gc=no > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> +$as_echo "$libc_linker_feature" >&6; } > >> +config_vars="$config_vars > >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> + > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> libc_linker_feature=no > >> diff --git a/configure.ac b/configure.ac > >> index fce967f2c2..cc47e56e82 100644 > >> --- a/configure.ac > >> +++ b/configure.ac > >> @@ -707,6 +707,23 @@ fi > >> rm -f conftest*]) > >> AC_SUBST(libc_cv_textrel_ifunc) > >> > >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> + libc_cv_gnu_retain, [dnl > >> +cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gnu_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> + 2>&AS_MESSAGE_LOG_FD ; then > >> + libc_cv_gnu_retain=yes > >> +fi > >> +rm -f conftest*]) > >> +if test $libc_cv_gnu_retain = yes; then > >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> +fi > >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> libc_cv_gcc_incompatible_alias, [dnl > >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> AC_SUBST(libc_cv_z_execstack) > >> > >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> + > >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> [-Wl,--no-dynamic-linker], > >> [libc_cv_no_dynamic_linker=yes], > >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> index 546fc26a7b..127ea656c2 100644 > >> --- a/include/libc-symbols.h > >> +++ b/include/libc-symbols.h > >> @@ -352,6 +352,12 @@ for linking") > >> > >> */ > >> > >> +#ifdef HAVE_GNU_RETAIN > >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> +#else > >> +# define attribute_used_retain __attribute__ ((__used__)) > >> +#endif > >> + > >> /* Symbol set support macros. */ > >> > >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> @@ -367,12 +373,12 @@ for linking") > >> /* When building a shared library, make the set section writable, > >> because it will need to be relocated at run time anyway. */ > >> # define _elf_set_element(set, symbol) \ > >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #else > >> # define _elf_set_element(set, symbol) \ > >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #endif > >> > >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> diff --git a/libio/Makefile b/libio/Makefile > >> index 12ce41038f..c9c232ebc2 100644 > >> --- a/libio/Makefile > >> +++ b/libio/Makefile > >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> $(objpfx)tst-bz24228-mem.out > >> endif > >> + > >> +tests += tst-cleanup-default > >> +tests-static += tst-cleanup-default > >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > > > >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > > Added. > > >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> + > >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > > > >Same here. > > Added. > > >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > >> +endif > >> endif > >> > >> include ../Rules > >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> endif > >> > >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> + > >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> + > >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> > >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> $(common-objpfx)libio/; \ > >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > >> new file mode 100644 > >> index 0000000000..7f0a34a91e > >> --- /dev/null > >> +++ b/libio/tst-cleanup.c > >> @@ -0,0 +1,33 @@ > > > >Please add a comment saying that test --gc-sections. > > OK, added. > > >> +/* Copyright (C) 2021 Free Software Foundation, Inc. > >> + This file is part of the GNU C Library. > >> + > >> + The GNU C Library is free software; you can redistribute it and/or > >> + modify it under the terms of the GNU Lesser General Public > >> + License as published by the Free Software Foundation; either > >> + version 2.1 of the License, or (at your option) any later version. > >> + > >> + The GNU C Library is distributed in the hope that it will be useful, > >> + but WITHOUT ANY WARRANTY; without even the implied warranty of > >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > >> + Lesser General Public License for more details. > >> + > >> + You should have received a copy of the GNU Lesser General Public > >> + License along with the GNU C Library; if not, see > >> + <https://www.gnu.org/licenses/>. */ > >> + > >> +/* Test that stdout is flushed after atexit callbacks were run. */ > >> + > >> +#include <stdio.h> > >> +#include <stdlib.h> > >> + > >> +void > >> +hook (void) > >> +{ > >> + puts ("hello"); > >> +} > >> + > >> +int > >> +main (void) > >> +{ > >> + atexit (hook); > >> +} > >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > >> new file mode 100644 > >> index 0000000000..ce01362503 > >> --- /dev/null > >> +++ b/libio/tst-cleanup.exp > >> @@ -0,0 +1 @@ > >> +hello > >> -- > >> 2.31.0.291.g576ba9dcdaf-goog > >> > > > > diff --git a/config.h.in b/config.h.in > index ca1547ae67..96a08c7757 100644 > --- a/config.h.in > +++ b/config.h.in > @@ -187,6 +187,9 @@ > /* Define if gcc supports attribute ifunc. */ > #undef HAVE_GCC_IFUNC > > +/* Define if CC supports attribute retain. */ > +#undef HAVE_GNU_RETAIN > + > /* Define if the linker defines __ehdr_start. */ > #undef HAVE_EHDR_START > > diff --git a/configure b/configure > index fcf43bf7de..e64b7f8efe 100755 > --- a/configure > +++ b/configure > @@ -4105,6 +4105,31 @@ fi > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > +$as_echo_n "checking for GNU attribute retain support... " >&6; } > +if ${libc_cv_gnu_retain+:} false; then : > + $as_echo_n "(cached) " >&6 > +else > + cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gnu_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > + 2>&5 ; then > + libc_cv_gnu_retain=yes > +fi > +rm -f conftest* > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > +$as_echo "$libc_cv_gnu_retain" >&6; } > +if test $libc_cv_gnu_retain = yes; then > + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > + > +fi > +config_vars="$config_vars > +have-gnu-retain = $libc_cv_gnu_retain" > + > # Check if gcc warns about alias for function with incompatible types. > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > @@ -5871,6 +5896,40 @@ fi > $as_echo "$libc_linker_feature" >&6; } > > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > +libc_linker_feature=no > +if test x"$gnu_ld" = x"yes"; then > + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > + if test -n "$libc_linker_check"; then > + cat > conftest.c <<EOF > +int _start (void) { return 42; } > +EOF > + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > + -fPIC -shared -o conftest.so conftest.c > + 1>&5' > + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > + (eval $ac_try) 2>&5 > + ac_status=$? > + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > + test $ac_status = 0; }; } > + then > + libc_linker_feature=yes > + fi > + rm -f conftest* > + fi > +fi > +if test $libc_linker_feature = yes; then > + libc_cv_z_start_stop_gc=yes > +else > + libc_cv_z_start_stop_gc=no > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > +$as_echo "$libc_linker_feature" >&6; } > +config_vars="$config_vars > +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > + > { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > libc_linker_feature=no > diff --git a/configure.ac b/configure.ac > index fce967f2c2..cc47e56e82 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -707,6 +707,23 @@ fi > rm -f conftest*]) > AC_SUBST(libc_cv_textrel_ifunc) > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > +AC_CACHE_CHECK([for GNU attribute retain support], > + libc_cv_gnu_retain, [dnl > +cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gnu_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > + 2>&AS_MESSAGE_LOG_FD ; then > + libc_cv_gnu_retain=yes > +fi > +rm -f conftest*]) > +if test $libc_cv_gnu_retain = yes; then > + AC_DEFINE(HAVE_GNU_RETAIN) > +fi > +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > + > # Check if gcc warns about alias for function with incompatible types. > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > libc_cv_gcc_incompatible_alias, [dnl > @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > AC_SUBST(libc_cv_z_execstack) > > +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > + > LIBC_LINKER_FEATURE([--no-dynamic-linker], > [-Wl,--no-dynamic-linker], > [libc_cv_no_dynamic_linker=yes], > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > index 546fc26a7b..127ea656c2 100644 > --- a/include/libc-symbols.h > +++ b/include/libc-symbols.h > @@ -352,6 +352,12 @@ for linking") > > */ > > +#ifdef HAVE_GNU_RETAIN > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > +#else > +# define attribute_used_retain __attribute__ ((__used__)) > +#endif > + > /* Symbol set support macros. */ > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > @@ -367,12 +373,12 @@ for linking") > /* When building a shared library, make the set section writable, > because it will need to be relocated at run time anyway. */ > # define _elf_set_element(set, symbol) \ > - static const void *__elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *__elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #else > # define _elf_set_element(set, symbol) \ > - static const void *const __elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #endif > > /* Define SET as a symbol set. This may be required (it is in a.out) to > diff --git a/libio/Makefile b/libio/Makefile > index 12ce41038f..ad0d53bb49 100644 > --- a/libio/Makefile > +++ b/libio/Makefile > @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > $(objpfx)tst-bz24228-mem.out > endif > + > +tests += tst-cleanup-default tst-cleanup-default-static > +tests-static += tst-cleanup-default-static > +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > + > +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > +endif > endif > > include ../Rules > @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > + $(compile.c) -o $@ > +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c > + $(compile.c) -o $@ > + > +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > + $(compile.c) -o $@ Please add a separate .c file for each test to get the correct dependency. > +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-nostart-stop-gc-static.o: tst-cleanup.c > + $(compile.c) -o $@ > + > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ > diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > new file mode 100644 > index 0000000000..837feac164 > --- /dev/null > +++ b/libio/tst-cleanup.c > @@ -0,0 +1,34 @@ > +/* Copyright (C) 2021 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + <https://www.gnu.org/licenses/>. */ > + > +/* Test that stdout is flushed after atexit callbacks were run, even if the > + * executable is linked with --gc-sections. */ > + > +#include <stdio.h> > +#include <stdlib.h> > + > +void > +hook (void) > +{ > + puts ("hello"); > +} > + > +int > +main (void) > +{ > + atexit (hook); > +} > diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > new file mode 100644 > index 0000000000..ce01362503 > --- /dev/null > +++ b/libio/tst-cleanup.exp > @@ -0,0 +1 @@ > +hello > -- > 2.31.0.208.g409f899ff0-goog > -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-02 14:14 ` H.J. Lu @ 2021-04-02 17:09 ` Fangrui Song 2021-04-02 17:33 ` H.J. Lu 2021-04-03 18:02 ` Fangrui Song 1 sibling, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-04-02 17:09 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-04-02, H.J. Lu wrote: >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: >> >> On 2021-04-01, H.J. Lu wrote: >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined >> >> variables will be retained by the linker. >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> >> will not be optimized out; 'retain' prevents section garbage collection >> >> if the linker support SHF_GNU_RETAIN. >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> >> identifier name sections to be GCed even if there are live >> >> __start_/__stop_ references. >> >> >> >> Without the change, there are some static linking problems, e.g. >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> >> stdout is not flushed on exit. >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> >> --- >> >> Changes in v1 -> v2: >> >> * Define attribute_used_retain_section >> >> Changes in v2 -> v3: >> >> * Use attribute_used_retain instead attribute_used_retain_section >> >> Changes in v3 -> v4: >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests >> >> Changes in v4 -> v5: >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported >> >> * Rename *gcc_retain* to *gnu_retain* >> >> --- >> >> config.h.in | 3 +++ >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ >> >> configure.ac | 21 +++++++++++++++ >> >> include/libc-symbols.h | 14 +++++++--- >> >> libio/Makefile | 32 +++++++++++++++++++++++ >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ >> >> libio/tst-cleanup.exp | 1 + >> >> 7 files changed, 159 insertions(+), 4 deletions(-) >> >> create mode 100644 libio/tst-cleanup.c >> >> create mode 100644 libio/tst-cleanup.exp >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> index ca1547ae67..96a08c7757 100644 >> >> --- a/config.h.in >> >> +++ b/config.h.in >> >> @@ -187,6 +187,9 @@ >> >> /* Define if gcc supports attribute ifunc. */ >> >> #undef HAVE_GCC_IFUNC >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> +#undef HAVE_GNU_RETAIN >> >> + >> >> /* Define if the linker defines __ehdr_start. */ >> >> #undef HAVE_EHDR_START >> >> >> >> diff --git a/configure b/configure >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> --- a/configure >> >> +++ b/configure >> >> @@ -4105,6 +4105,31 @@ fi >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> + $as_echo_n "(cached) " >&6 >> >> +else >> >> + cat > conftest.c <<EOF >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> +EOF >> >> +libc_cv_gnu_retain=no >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> + 2>&5 ; then >> >> + libc_cv_gnu_retain=yes >> >> +fi >> >> +rm -f conftest* >> >> +fi >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> +if test $libc_cv_gnu_retain = yes; then >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> + >> >> +fi >> >> +config_vars="$config_vars >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> + >> >> # Check if gcc warns about alias for function with incompatible types. >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> @@ -5871,6 +5896,40 @@ fi >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> +libc_linker_feature=no >> >> +if test x"$gnu_ld" = x"yes"; then >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> + if test -n "$libc_linker_check"; then >> >> + cat > conftest.c <<EOF >> >> +int _start (void) { return 42; } >> >> +EOF >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> + -fPIC -shared -o conftest.so conftest.c >> >> + 1>&5' >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> + (eval $ac_try) 2>&5 >> >> + ac_status=$? >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> + test $ac_status = 0; }; } >> >> + then >> >> + libc_linker_feature=yes >> >> + fi >> >> + rm -f conftest* >> >> + fi >> >> +fi >> >> +if test $libc_linker_feature = yes; then >> >> + libc_cv_z_start_stop_gc=yes >> >> +else >> >> + libc_cv_z_start_stop_gc=no >> >> +fi >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> +config_vars="$config_vars >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> + >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> libc_linker_feature=no >> >> diff --git a/configure.ac b/configure.ac >> >> index fce967f2c2..cc47e56e82 100644 >> >> --- a/configure.ac >> >> +++ b/configure.ac >> >> @@ -707,6 +707,23 @@ fi >> >> rm -f conftest*]) >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> + libc_cv_gnu_retain, [dnl >> >> +cat > conftest.c <<EOF >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> +EOF >> >> +libc_cv_gnu_retain=no >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> + libc_cv_gnu_retain=yes >> >> +fi >> >> +rm -f conftest*]) >> >> +if test $libc_cv_gnu_retain = yes; then >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> +fi >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> + >> >> # Check if gcc warns about alias for function with incompatible types. >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> + >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> [-Wl,--no-dynamic-linker], >> >> [libc_cv_no_dynamic_linker=yes], >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> index 546fc26a7b..127ea656c2 100644 >> >> --- a/include/libc-symbols.h >> >> +++ b/include/libc-symbols.h >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> */ >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> +#else >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> +#endif >> >> + >> >> /* Symbol set support macros. */ >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> @@ -367,12 +373,12 @@ for linking") >> >> /* When building a shared library, make the set section writable, >> >> because it will need to be relocated at run time anyway. */ >> >> # define _elf_set_element(set, symbol) \ >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> #else >> >> # define _elf_set_element(set, symbol) \ >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> #endif >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> index 12ce41038f..c9c232ebc2 100644 >> >> --- a/libio/Makefile >> >> +++ b/libio/Makefile >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> $(objpfx)tst-bz24228-mem.out >> >> endif >> >> + >> >> +tests += tst-cleanup-default >> >> +tests-static += tst-cleanup-default >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out >> > >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. >> >> Added. >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> + >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out >> > >> >Same here. >> >> Added. >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc >> >> +endif >> >> endif >> >> >> >> include ../Rules >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> endif >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> + >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> + >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> $(common-objpfx)libio/; \ >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> >> new file mode 100644 >> >> index 0000000000..7f0a34a91e >> >> --- /dev/null >> >> +++ b/libio/tst-cleanup.c >> >> @@ -0,0 +1,33 @@ >> > >> >Please add a comment saying that test --gc-sections. >> >> OK, added. >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> >> + This file is part of the GNU C Library. >> >> + >> >> + The GNU C Library is free software; you can redistribute it and/or >> >> + modify it under the terms of the GNU Lesser General Public >> >> + License as published by the Free Software Foundation; either >> >> + version 2.1 of the License, or (at your option) any later version. >> >> + >> >> + The GNU C Library is distributed in the hope that it will be useful, >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> >> + Lesser General Public License for more details. >> >> + >> >> + You should have received a copy of the GNU Lesser General Public >> >> + License along with the GNU C Library; if not, see >> >> + <https://www.gnu.org/licenses/>. */ >> >> + >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> >> + >> >> +#include <stdio.h> >> >> +#include <stdlib.h> >> >> + >> >> +void >> >> +hook (void) >> >> +{ >> >> + puts ("hello"); >> >> +} >> >> + >> >> +int >> >> +main (void) >> >> +{ >> >> + atexit (hook); >> >> +} >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> >> new file mode 100644 >> >> index 0000000000..ce01362503 >> >> --- /dev/null >> >> +++ b/libio/tst-cleanup.exp >> >> @@ -0,0 +1 @@ >> >> +hello >> >> -- >> >> 2.31.0.291.g576ba9dcdaf-goog >> >> >> > >> >> diff --git a/config.h.in b/config.h.in >> index ca1547ae67..96a08c7757 100644 >> --- a/config.h.in >> +++ b/config.h.in >> @@ -187,6 +187,9 @@ >> /* Define if gcc supports attribute ifunc. */ >> #undef HAVE_GCC_IFUNC >> >> +/* Define if CC supports attribute retain. */ >> +#undef HAVE_GNU_RETAIN >> + >> /* Define if the linker defines __ehdr_start. */ >> #undef HAVE_EHDR_START >> >> diff --git a/configure b/configure >> index fcf43bf7de..e64b7f8efe 100755 >> --- a/configure >> +++ b/configure >> @@ -4105,6 +4105,31 @@ fi >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> +if ${libc_cv_gnu_retain+:} false; then : >> + $as_echo_n "(cached) " >&6 >> +else >> + cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gnu_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> + 2>&5 ; then >> + libc_cv_gnu_retain=yes >> +fi >> +rm -f conftest* >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> +if test $libc_cv_gnu_retain = yes; then >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> + >> +fi >> +config_vars="$config_vars >> +have-gnu-retain = $libc_cv_gnu_retain" >> + >> # Check if gcc warns about alias for function with incompatible types. >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> @@ -5871,6 +5896,40 @@ fi >> $as_echo "$libc_linker_feature" >&6; } >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> +libc_linker_feature=no >> +if test x"$gnu_ld" = x"yes"; then >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> + if test -n "$libc_linker_check"; then >> + cat > conftest.c <<EOF >> +int _start (void) { return 42; } >> +EOF >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> + -fPIC -shared -o conftest.so conftest.c >> + 1>&5' >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> + (eval $ac_try) 2>&5 >> + ac_status=$? >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> + test $ac_status = 0; }; } >> + then >> + libc_linker_feature=yes >> + fi >> + rm -f conftest* >> + fi >> +fi >> +if test $libc_linker_feature = yes; then >> + libc_cv_z_start_stop_gc=yes >> +else >> + libc_cv_z_start_stop_gc=no >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> +$as_echo "$libc_linker_feature" >&6; } >> +config_vars="$config_vars >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> + >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> libc_linker_feature=no >> diff --git a/configure.ac b/configure.ac >> index fce967f2c2..cc47e56e82 100644 >> --- a/configure.ac >> +++ b/configure.ac >> @@ -707,6 +707,23 @@ fi >> rm -f conftest*]) >> AC_SUBST(libc_cv_textrel_ifunc) >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> +AC_CACHE_CHECK([for GNU attribute retain support], >> + libc_cv_gnu_retain, [dnl >> +cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gnu_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> + 2>&AS_MESSAGE_LOG_FD ; then >> + libc_cv_gnu_retain=yes >> +fi >> +rm -f conftest*]) >> +if test $libc_cv_gnu_retain = yes; then >> + AC_DEFINE(HAVE_GNU_RETAIN) >> +fi >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> + >> # Check if gcc warns about alias for function with incompatible types. >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> libc_cv_gcc_incompatible_alias, [dnl >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> AC_SUBST(libc_cv_z_execstack) >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> + >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> [-Wl,--no-dynamic-linker], >> [libc_cv_no_dynamic_linker=yes], >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> index 546fc26a7b..127ea656c2 100644 >> --- a/include/libc-symbols.h >> +++ b/include/libc-symbols.h >> @@ -352,6 +352,12 @@ for linking") >> >> */ >> >> +#ifdef HAVE_GNU_RETAIN >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> +#else >> +# define attribute_used_retain __attribute__ ((__used__)) >> +#endif >> + >> /* Symbol set support macros. */ >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> @@ -367,12 +373,12 @@ for linking") >> /* When building a shared library, make the set section writable, >> because it will need to be relocated at run time anyway. */ >> # define _elf_set_element(set, symbol) \ >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #else >> # define _elf_set_element(set, symbol) \ >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #endif >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> diff --git a/libio/Makefile b/libio/Makefile >> index 12ce41038f..ad0d53bb49 100644 >> --- a/libio/Makefile >> +++ b/libio/Makefile >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> $(objpfx)tst-bz24228-mem.out >> endif >> + >> +tests += tst-cleanup-default tst-cleanup-default-static >> +tests-static += tst-cleanup-default-static >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections >> + >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc >> +endif >> endif >> >> include ../Rules >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> endif >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> + $(compile.c) -o $@ >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c >> + $(compile.c) -o $@ > >Please add a separate .c file for each test to get the correct dependency. This is unnecessary. $(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c does the work perfectly. >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> $(common-objpfx)libio/; \ >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> new file mode 100644 >> index 0000000000..837feac164 >> --- /dev/null >> +++ b/libio/tst-cleanup.c >> @@ -0,0 +1,34 @@ >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> + This file is part of the GNU C Library. >> + >> + The GNU C Library is free software; you can redistribute it and/or >> + modify it under the terms of the GNU Lesser General Public >> + License as published by the Free Software Foundation; either >> + version 2.1 of the License, or (at your option) any later version. >> + >> + The GNU C Library is distributed in the hope that it will be useful, >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> + Lesser General Public License for more details. >> + >> + You should have received a copy of the GNU Lesser General Public >> + License along with the GNU C Library; if not, see >> + <https://www.gnu.org/licenses/>. */ >> + >> +/* Test that stdout is flushed after atexit callbacks were run, even if the >> + * executable is linked with --gc-sections. */ >> + >> +#include <stdio.h> >> +#include <stdlib.h> >> + >> +void >> +hook (void) >> +{ >> + puts ("hello"); >> +} >> + >> +int >> +main (void) >> +{ >> + atexit (hook); >> +} >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> new file mode 100644 >> index 0000000000..ce01362503 >> --- /dev/null >> +++ b/libio/tst-cleanup.exp >> @@ -0,0 +1 @@ >> +hello >> -- >> 2.31.0.208.g409f899ff0-goog >> > > >-- >H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-02 17:09 ` Fangrui Song @ 2021-04-02 17:33 ` H.J. Lu 0 siblings, 0 replies; 40+ messages in thread From: H.J. Lu @ 2021-04-02 17:33 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Fri, Apr 2, 2021 at 10:09 AM Fangrui Song <maskray@google.com> wrote: > > On 2021-04-02, H.J. Lu wrote: > >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: > >> > >> On 2021-04-01, H.J. Lu wrote: > >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > >> >> > >> >> So that text_set_element/data_set_element/bss_set_element defined > >> >> variables will be retained by the linker. > >> >> > >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> >> will not be optimized out; 'retain' prevents section garbage collection > >> >> if the linker support SHF_GNU_RETAIN. > >> >> > >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> >> identifier name sections to be GCed even if there are live > >> >> __start_/__stop_ references. > >> >> > >> >> Without the change, there are some static linking problems, e.g. > >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> >> stdout is not flushed on exit. > >> >> > >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> >> --- > >> >> Changes in v1 -> v2: > >> >> * Define attribute_used_retain_section > >> >> Changes in v2 -> v3: > >> >> * Use attribute_used_retain instead attribute_used_retain_section > >> >> Changes in v3 -> v4: > >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> >> Changes in v4 -> v5: > >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > >> >> * Rename *gcc_retain* to *gnu_retain* > >> >> --- > >> >> config.h.in | 3 +++ > >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > >> >> configure.ac | 21 +++++++++++++++ > >> >> include/libc-symbols.h | 14 +++++++--- > >> >> libio/Makefile | 32 +++++++++++++++++++++++ > >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > >> >> libio/tst-cleanup.exp | 1 + > >> >> 7 files changed, 159 insertions(+), 4 deletions(-) > >> >> create mode 100644 libio/tst-cleanup.c > >> >> create mode 100644 libio/tst-cleanup.exp > >> >> > >> >> diff --git a/config.h.in b/config.h.in > >> >> index ca1547ae67..96a08c7757 100644 > >> >> --- a/config.h.in > >> >> +++ b/config.h.in > >> >> @@ -187,6 +187,9 @@ > >> >> /* Define if gcc supports attribute ifunc. */ > >> >> #undef HAVE_GCC_IFUNC > >> >> > >> >> +/* Define if CC supports attribute retain. */ > >> >> +#undef HAVE_GNU_RETAIN > >> >> + > >> >> /* Define if the linker defines __ehdr_start. */ > >> >> #undef HAVE_EHDR_START > >> >> > >> >> diff --git a/configure b/configure > >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> --- a/configure > >> >> +++ b/configure > >> >> @@ -4105,6 +4105,31 @@ fi > >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> > >> >> > >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> + $as_echo_n "(cached) " >&6 > >> >> +else > >> >> + cat > conftest.c <<EOF > >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> +EOF > >> >> +libc_cv_gnu_retain=no > >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> + 2>&5 ; then > >> >> + libc_cv_gnu_retain=yes > >> >> +fi > >> >> +rm -f conftest* > >> >> +fi > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> + > >> >> +fi > >> >> +config_vars="$config_vars > >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> + > >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> @@ -5871,6 +5896,40 @@ fi > >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> > >> >> > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> +libc_linker_feature=no > >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> + if test -n "$libc_linker_check"; then > >> >> + cat > conftest.c <<EOF > >> >> +int _start (void) { return 42; } > >> >> +EOF > >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> + 1>&5' > >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> + (eval $ac_try) 2>&5 > >> >> + ac_status=$? > >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> + test $ac_status = 0; }; } > >> >> + then > >> >> + libc_linker_feature=yes > >> >> + fi > >> >> + rm -f conftest* > >> >> + fi > >> >> +fi > >> >> +if test $libc_linker_feature = yes; then > >> >> + libc_cv_z_start_stop_gc=yes > >> >> +else > >> >> + libc_cv_z_start_stop_gc=no > >> >> +fi > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> +config_vars="$config_vars > >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> + > >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> libc_linker_feature=no > >> >> diff --git a/configure.ac b/configure.ac > >> >> index fce967f2c2..cc47e56e82 100644 > >> >> --- a/configure.ac > >> >> +++ b/configure.ac > >> >> @@ -707,6 +707,23 @@ fi > >> >> rm -f conftest*]) > >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> > >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> + libc_cv_gnu_retain, [dnl > >> >> +cat > conftest.c <<EOF > >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> +EOF > >> >> +libc_cv_gnu_retain=no > >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> + libc_cv_gnu_retain=yes > >> >> +fi > >> >> +rm -f conftest*]) > >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> +fi > >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> + > >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> AC_SUBST(libc_cv_z_execstack) > >> >> > >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> + > >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> [-Wl,--no-dynamic-linker], > >> >> [libc_cv_no_dynamic_linker=yes], > >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> index 546fc26a7b..127ea656c2 100644 > >> >> --- a/include/libc-symbols.h > >> >> +++ b/include/libc-symbols.h > >> >> @@ -352,6 +352,12 @@ for linking") > >> >> > >> >> */ > >> >> > >> >> +#ifdef HAVE_GNU_RETAIN > >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> +#else > >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> +#endif > >> >> + > >> >> /* Symbol set support macros. */ > >> >> > >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> @@ -367,12 +373,12 @@ for linking") > >> >> /* When building a shared library, make the set section writable, > >> >> because it will need to be relocated at run time anyway. */ > >> >> # define _elf_set_element(set, symbol) \ > >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> #else > >> >> # define _elf_set_element(set, symbol) \ > >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> #endif > >> >> > >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> index 12ce41038f..c9c232ebc2 100644 > >> >> --- a/libio/Makefile > >> >> +++ b/libio/Makefile > >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> $(objpfx)tst-bz24228-mem.out > >> >> endif > >> >> + > >> >> +tests += tst-cleanup-default > >> >> +tests-static += tst-cleanup-default > >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >> > > >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > >> > >> Added. > >> > >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> + > >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >> > > >> >Same here. > >> > >> Added. > >> > >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > >> >> +endif > >> >> endif > >> >> > >> >> include ../Rules > >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> endif > >> >> > >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> + > >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> + > >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> > >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> $(common-objpfx)libio/; \ > >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > >> >> new file mode 100644 > >> >> index 0000000000..7f0a34a91e > >> >> --- /dev/null > >> >> +++ b/libio/tst-cleanup.c > >> >> @@ -0,0 +1,33 @@ > >> > > >> >Please add a comment saying that test --gc-sections. > >> > >> OK, added. > >> > >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. > >> >> + This file is part of the GNU C Library. > >> >> + > >> >> + The GNU C Library is free software; you can redistribute it and/or > >> >> + modify it under the terms of the GNU Lesser General Public > >> >> + License as published by the Free Software Foundation; either > >> >> + version 2.1 of the License, or (at your option) any later version. > >> >> + > >> >> + The GNU C Library is distributed in the hope that it will be useful, > >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of > >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > >> >> + Lesser General Public License for more details. > >> >> + > >> >> + You should have received a copy of the GNU Lesser General Public > >> >> + License along with the GNU C Library; if not, see > >> >> + <https://www.gnu.org/licenses/>. */ > >> >> + > >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ > >> >> + > >> >> +#include <stdio.h> > >> >> +#include <stdlib.h> > >> >> + > >> >> +void > >> >> +hook (void) > >> >> +{ > >> >> + puts ("hello"); > >> >> +} > >> >> + > >> >> +int > >> >> +main (void) > >> >> +{ > >> >> + atexit (hook); > >> >> +} > >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > >> >> new file mode 100644 > >> >> index 0000000000..ce01362503 > >> >> --- /dev/null > >> >> +++ b/libio/tst-cleanup.exp > >> >> @@ -0,0 +1 @@ > >> >> +hello > >> >> -- > >> >> 2.31.0.291.g576ba9dcdaf-goog > >> >> > >> > > >> > >> diff --git a/config.h.in b/config.h.in > >> index ca1547ae67..96a08c7757 100644 > >> --- a/config.h.in > >> +++ b/config.h.in > >> @@ -187,6 +187,9 @@ > >> /* Define if gcc supports attribute ifunc. */ > >> #undef HAVE_GCC_IFUNC > >> > >> +/* Define if CC supports attribute retain. */ > >> +#undef HAVE_GNU_RETAIN > >> + > >> /* Define if the linker defines __ehdr_start. */ > >> #undef HAVE_EHDR_START > >> > >> diff --git a/configure b/configure > >> index fcf43bf7de..e64b7f8efe 100755 > >> --- a/configure > >> +++ b/configure > >> @@ -4105,6 +4105,31 @@ fi > >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> > >> > >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> +if ${libc_cv_gnu_retain+:} false; then : > >> + $as_echo_n "(cached) " >&6 > >> +else > >> + cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gnu_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> + 2>&5 ; then > >> + libc_cv_gnu_retain=yes > >> +fi > >> +rm -f conftest* > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> +if test $libc_cv_gnu_retain = yes; then > >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> + > >> +fi > >> +config_vars="$config_vars > >> +have-gnu-retain = $libc_cv_gnu_retain" > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> @@ -5871,6 +5896,40 @@ fi > >> $as_echo "$libc_linker_feature" >&6; } > >> > >> > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> +libc_linker_feature=no > >> +if test x"$gnu_ld" = x"yes"; then > >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> + if test -n "$libc_linker_check"; then > >> + cat > conftest.c <<EOF > >> +int _start (void) { return 42; } > >> +EOF > >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> + -fPIC -shared -o conftest.so conftest.c > >> + 1>&5' > >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> + (eval $ac_try) 2>&5 > >> + ac_status=$? > >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> + test $ac_status = 0; }; } > >> + then > >> + libc_linker_feature=yes > >> + fi > >> + rm -f conftest* > >> + fi > >> +fi > >> +if test $libc_linker_feature = yes; then > >> + libc_cv_z_start_stop_gc=yes > >> +else > >> + libc_cv_z_start_stop_gc=no > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> +$as_echo "$libc_linker_feature" >&6; } > >> +config_vars="$config_vars > >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> + > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> libc_linker_feature=no > >> diff --git a/configure.ac b/configure.ac > >> index fce967f2c2..cc47e56e82 100644 > >> --- a/configure.ac > >> +++ b/configure.ac > >> @@ -707,6 +707,23 @@ fi > >> rm -f conftest*]) > >> AC_SUBST(libc_cv_textrel_ifunc) > >> > >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> + libc_cv_gnu_retain, [dnl > >> +cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gnu_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> + 2>&AS_MESSAGE_LOG_FD ; then > >> + libc_cv_gnu_retain=yes > >> +fi > >> +rm -f conftest*]) > >> +if test $libc_cv_gnu_retain = yes; then > >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> +fi > >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> libc_cv_gcc_incompatible_alias, [dnl > >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> AC_SUBST(libc_cv_z_execstack) > >> > >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> + > >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> [-Wl,--no-dynamic-linker], > >> [libc_cv_no_dynamic_linker=yes], > >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> index 546fc26a7b..127ea656c2 100644 > >> --- a/include/libc-symbols.h > >> +++ b/include/libc-symbols.h > >> @@ -352,6 +352,12 @@ for linking") > >> > >> */ > >> > >> +#ifdef HAVE_GNU_RETAIN > >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> +#else > >> +# define attribute_used_retain __attribute__ ((__used__)) > >> +#endif > >> + > >> /* Symbol set support macros. */ > >> > >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> @@ -367,12 +373,12 @@ for linking") > >> /* When building a shared library, make the set section writable, > >> because it will need to be relocated at run time anyway. */ > >> # define _elf_set_element(set, symbol) \ > >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #else > >> # define _elf_set_element(set, symbol) \ > >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #endif > >> > >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> diff --git a/libio/Makefile b/libio/Makefile > >> index 12ce41038f..ad0d53bb49 100644 > >> --- a/libio/Makefile > >> +++ b/libio/Makefile > >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> $(objpfx)tst-bz24228-mem.out > >> endif > >> + > >> +tests += tst-cleanup-default tst-cleanup-default-static > >> +tests-static += tst-cleanup-default-static > >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> + > >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> +endif > >> endif > >> > >> include ../Rules > >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> endif > >> > >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> + > >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > >> + $(compile.c) -o $@ > > > >Please add a separate .c file for each test to get the correct dependency. > > This is unnecessary. > > $(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > > does the work perfectly. > What does tst-cleanup-start-stop-gc-static.o.d contain? -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-02 14:14 ` H.J. Lu 2021-04-02 17:09 ` Fangrui Song @ 2021-04-03 18:02 ` Fangrui Song 2021-04-03 20:47 ` H.J. Lu 1 sibling, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-04-03 18:02 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-04-02, H.J. Lu wrote: >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: >> >> On 2021-04-01, H.J. Lu wrote: >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined >> >> variables will be retained by the linker. >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> >> will not be optimized out; 'retain' prevents section garbage collection >> >> if the linker support SHF_GNU_RETAIN. >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> >> identifier name sections to be GCed even if there are live >> >> __start_/__stop_ references. >> >> >> >> Without the change, there are some static linking problems, e.g. >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> >> stdout is not flushed on exit. >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> >> --- >> >> Changes in v1 -> v2: >> >> * Define attribute_used_retain_section >> >> Changes in v2 -> v3: >> >> * Use attribute_used_retain instead attribute_used_retain_section >> >> Changes in v3 -> v4: >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests >> >> Changes in v4 -> v5: >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported >> >> * Rename *gcc_retain* to *gnu_retain* >> >> --- >> >> config.h.in | 3 +++ >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ >> >> configure.ac | 21 +++++++++++++++ >> >> include/libc-symbols.h | 14 +++++++--- >> >> libio/Makefile | 32 +++++++++++++++++++++++ >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ >> >> libio/tst-cleanup.exp | 1 + >> >> 7 files changed, 159 insertions(+), 4 deletions(-) >> >> create mode 100644 libio/tst-cleanup.c >> >> create mode 100644 libio/tst-cleanup.exp >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> index ca1547ae67..96a08c7757 100644 >> >> --- a/config.h.in >> >> +++ b/config.h.in >> >> @@ -187,6 +187,9 @@ >> >> /* Define if gcc supports attribute ifunc. */ >> >> #undef HAVE_GCC_IFUNC >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> +#undef HAVE_GNU_RETAIN >> >> + >> >> /* Define if the linker defines __ehdr_start. */ >> >> #undef HAVE_EHDR_START >> >> >> >> diff --git a/configure b/configure >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> --- a/configure >> >> +++ b/configure >> >> @@ -4105,6 +4105,31 @@ fi >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> + $as_echo_n "(cached) " >&6 >> >> +else >> >> + cat > conftest.c <<EOF >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> +EOF >> >> +libc_cv_gnu_retain=no >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> + 2>&5 ; then >> >> + libc_cv_gnu_retain=yes >> >> +fi >> >> +rm -f conftest* >> >> +fi >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> +if test $libc_cv_gnu_retain = yes; then >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> + >> >> +fi >> >> +config_vars="$config_vars >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> + >> >> # Check if gcc warns about alias for function with incompatible types. >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> @@ -5871,6 +5896,40 @@ fi >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> +libc_linker_feature=no >> >> +if test x"$gnu_ld" = x"yes"; then >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> + if test -n "$libc_linker_check"; then >> >> + cat > conftest.c <<EOF >> >> +int _start (void) { return 42; } >> >> +EOF >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> + -fPIC -shared -o conftest.so conftest.c >> >> + 1>&5' >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> + (eval $ac_try) 2>&5 >> >> + ac_status=$? >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> + test $ac_status = 0; }; } >> >> + then >> >> + libc_linker_feature=yes >> >> + fi >> >> + rm -f conftest* >> >> + fi >> >> +fi >> >> +if test $libc_linker_feature = yes; then >> >> + libc_cv_z_start_stop_gc=yes >> >> +else >> >> + libc_cv_z_start_stop_gc=no >> >> +fi >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> +config_vars="$config_vars >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> + >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> libc_linker_feature=no >> >> diff --git a/configure.ac b/configure.ac >> >> index fce967f2c2..cc47e56e82 100644 >> >> --- a/configure.ac >> >> +++ b/configure.ac >> >> @@ -707,6 +707,23 @@ fi >> >> rm -f conftest*]) >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> + libc_cv_gnu_retain, [dnl >> >> +cat > conftest.c <<EOF >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> +EOF >> >> +libc_cv_gnu_retain=no >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> + libc_cv_gnu_retain=yes >> >> +fi >> >> +rm -f conftest*]) >> >> +if test $libc_cv_gnu_retain = yes; then >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> +fi >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> + >> >> # Check if gcc warns about alias for function with incompatible types. >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> + >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> [-Wl,--no-dynamic-linker], >> >> [libc_cv_no_dynamic_linker=yes], >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> index 546fc26a7b..127ea656c2 100644 >> >> --- a/include/libc-symbols.h >> >> +++ b/include/libc-symbols.h >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> */ >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> +#else >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> +#endif >> >> + >> >> /* Symbol set support macros. */ >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> @@ -367,12 +373,12 @@ for linking") >> >> /* When building a shared library, make the set section writable, >> >> because it will need to be relocated at run time anyway. */ >> >> # define _elf_set_element(set, symbol) \ >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> #else >> >> # define _elf_set_element(set, symbol) \ >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> #endif >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> index 12ce41038f..c9c232ebc2 100644 >> >> --- a/libio/Makefile >> >> +++ b/libio/Makefile >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> $(objpfx)tst-bz24228-mem.out >> >> endif >> >> + >> >> +tests += tst-cleanup-default >> >> +tests-static += tst-cleanup-default >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out >> > >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. >> >> Added. >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> + >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out >> > >> >Same here. >> >> Added. >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc >> >> +endif >> >> endif >> >> >> >> include ../Rules >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> endif >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> + >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> + >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> $(common-objpfx)libio/; \ >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> >> new file mode 100644 >> >> index 0000000000..7f0a34a91e >> >> --- /dev/null >> >> +++ b/libio/tst-cleanup.c >> >> @@ -0,0 +1,33 @@ >> > >> >Please add a comment saying that test --gc-sections. >> >> OK, added. >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> >> + This file is part of the GNU C Library. >> >> + >> >> + The GNU C Library is free software; you can redistribute it and/or >> >> + modify it under the terms of the GNU Lesser General Public >> >> + License as published by the Free Software Foundation; either >> >> + version 2.1 of the License, or (at your option) any later version. >> >> + >> >> + The GNU C Library is distributed in the hope that it will be useful, >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> >> + Lesser General Public License for more details. >> >> + >> >> + You should have received a copy of the GNU Lesser General Public >> >> + License along with the GNU C Library; if not, see >> >> + <https://www.gnu.org/licenses/>. */ >> >> + >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> >> + >> >> +#include <stdio.h> >> >> +#include <stdlib.h> >> >> + >> >> +void >> >> +hook (void) >> >> +{ >> >> + puts ("hello"); >> >> +} >> >> + >> >> +int >> >> +main (void) >> >> +{ >> >> + atexit (hook); >> >> +} >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> >> new file mode 100644 >> >> index 0000000000..ce01362503 >> >> --- /dev/null >> >> +++ b/libio/tst-cleanup.exp >> >> @@ -0,0 +1 @@ >> >> +hello >> >> -- >> >> 2.31.0.291.g576ba9dcdaf-goog >> >> >> > >> >> diff --git a/config.h.in b/config.h.in >> index ca1547ae67..96a08c7757 100644 >> --- a/config.h.in >> +++ b/config.h.in >> @@ -187,6 +187,9 @@ >> /* Define if gcc supports attribute ifunc. */ >> #undef HAVE_GCC_IFUNC >> >> +/* Define if CC supports attribute retain. */ >> +#undef HAVE_GNU_RETAIN >> + >> /* Define if the linker defines __ehdr_start. */ >> #undef HAVE_EHDR_START >> >> diff --git a/configure b/configure >> index fcf43bf7de..e64b7f8efe 100755 >> --- a/configure >> +++ b/configure >> @@ -4105,6 +4105,31 @@ fi >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> +if ${libc_cv_gnu_retain+:} false; then : >> + $as_echo_n "(cached) " >&6 >> +else >> + cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gnu_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> + 2>&5 ; then >> + libc_cv_gnu_retain=yes >> +fi >> +rm -f conftest* >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> +if test $libc_cv_gnu_retain = yes; then >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> + >> +fi >> +config_vars="$config_vars >> +have-gnu-retain = $libc_cv_gnu_retain" >> + >> # Check if gcc warns about alias for function with incompatible types. >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> @@ -5871,6 +5896,40 @@ fi >> $as_echo "$libc_linker_feature" >&6; } >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> +libc_linker_feature=no >> +if test x"$gnu_ld" = x"yes"; then >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> + if test -n "$libc_linker_check"; then >> + cat > conftest.c <<EOF >> +int _start (void) { return 42; } >> +EOF >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> + -fPIC -shared -o conftest.so conftest.c >> + 1>&5' >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> + (eval $ac_try) 2>&5 >> + ac_status=$? >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> + test $ac_status = 0; }; } >> + then >> + libc_linker_feature=yes >> + fi >> + rm -f conftest* >> + fi >> +fi >> +if test $libc_linker_feature = yes; then >> + libc_cv_z_start_stop_gc=yes >> +else >> + libc_cv_z_start_stop_gc=no >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> +$as_echo "$libc_linker_feature" >&6; } >> +config_vars="$config_vars >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> + >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> libc_linker_feature=no >> diff --git a/configure.ac b/configure.ac >> index fce967f2c2..cc47e56e82 100644 >> --- a/configure.ac >> +++ b/configure.ac >> @@ -707,6 +707,23 @@ fi >> rm -f conftest*]) >> AC_SUBST(libc_cv_textrel_ifunc) >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> +AC_CACHE_CHECK([for GNU attribute retain support], >> + libc_cv_gnu_retain, [dnl >> +cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gnu_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> + 2>&AS_MESSAGE_LOG_FD ; then >> + libc_cv_gnu_retain=yes >> +fi >> +rm -f conftest*]) >> +if test $libc_cv_gnu_retain = yes; then >> + AC_DEFINE(HAVE_GNU_RETAIN) >> +fi >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> + >> # Check if gcc warns about alias for function with incompatible types. >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> libc_cv_gcc_incompatible_alias, [dnl >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> AC_SUBST(libc_cv_z_execstack) >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> + >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> [-Wl,--no-dynamic-linker], >> [libc_cv_no_dynamic_linker=yes], >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> index 546fc26a7b..127ea656c2 100644 >> --- a/include/libc-symbols.h >> +++ b/include/libc-symbols.h >> @@ -352,6 +352,12 @@ for linking") >> >> */ >> >> +#ifdef HAVE_GNU_RETAIN >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> +#else >> +# define attribute_used_retain __attribute__ ((__used__)) >> +#endif >> + >> /* Symbol set support macros. */ >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> @@ -367,12 +373,12 @@ for linking") >> /* When building a shared library, make the set section writable, >> because it will need to be relocated at run time anyway. */ >> # define _elf_set_element(set, symbol) \ >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #else >> # define _elf_set_element(set, symbol) \ >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #endif >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> diff --git a/libio/Makefile b/libio/Makefile >> index 12ce41038f..ad0d53bb49 100644 >> --- a/libio/Makefile >> +++ b/libio/Makefile >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> $(objpfx)tst-bz24228-mem.out >> endif >> + >> +tests += tst-cleanup-default tst-cleanup-default-static >> +tests-static += tst-cleanup-default-static >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections >> + >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc >> +endif >> endif >> >> include ../Rules >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> endif >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> + $(compile.c) -o $@ >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c >> + $(compile.c) -o $@ > >Please add a separate .c file for each test to get the correct dependency. Changed this block to: @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) $(objpfx)tst-wfile-sync.out: $(gen-locales) endif +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-default.c: tst-cleanup.c + cp $< $@ +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c + cp $< $@ + +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c + cp $< $@ + +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c + cp $< $@ +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c + cp $< $@ + $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ $(common-objpfx)libio/; \ >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> $(common-objpfx)libio/; \ >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> new file mode 100644 >> index 0000000000..837feac164 >> --- /dev/null >> +++ b/libio/tst-cleanup.c >> @@ -0,0 +1,34 @@ >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> + This file is part of the GNU C Library. >> + >> + The GNU C Library is free software; you can redistribute it and/or >> + modify it under the terms of the GNU Lesser General Public >> + License as published by the Free Software Foundation; either >> + version 2.1 of the License, or (at your option) any later version. >> + >> + The GNU C Library is distributed in the hope that it will be useful, >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> + Lesser General Public License for more details. >> + >> + You should have received a copy of the GNU Lesser General Public >> + License along with the GNU C Library; if not, see >> + <https://www.gnu.org/licenses/>. */ >> + >> +/* Test that stdout is flushed after atexit callbacks were run, even if the >> + * executable is linked with --gc-sections. */ >> + >> +#include <stdio.h> >> +#include <stdlib.h> >> + >> +void >> +hook (void) >> +{ >> + puts ("hello"); >> +} >> + >> +int >> +main (void) >> +{ >> + atexit (hook); >> +} >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> new file mode 100644 >> index 0000000000..ce01362503 >> --- /dev/null >> +++ b/libio/tst-cleanup.exp >> @@ -0,0 +1 @@ >> +hello >> -- >> 2.31.0.208.g409f899ff0-goog >> > > >-- >H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-03 18:02 ` Fangrui Song @ 2021-04-03 20:47 ` H.J. Lu 2021-04-03 21:57 ` Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-04-03 20:47 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: > > > On 2021-04-02, H.J. Lu wrote: > >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: > >> > >> On 2021-04-01, H.J. Lu wrote: > >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > >> >> > >> >> So that text_set_element/data_set_element/bss_set_element defined > >> >> variables will be retained by the linker. > >> >> > >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> >> will not be optimized out; 'retain' prevents section garbage collection > >> >> if the linker support SHF_GNU_RETAIN. > >> >> > >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> >> identifier name sections to be GCed even if there are live > >> >> __start_/__stop_ references. > >> >> > >> >> Without the change, there are some static linking problems, e.g. > >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> >> stdout is not flushed on exit. > >> >> > >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> >> --- > >> >> Changes in v1 -> v2: > >> >> * Define attribute_used_retain_section > >> >> Changes in v2 -> v3: > >> >> * Use attribute_used_retain instead attribute_used_retain_section > >> >> Changes in v3 -> v4: > >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> >> Changes in v4 -> v5: > >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > >> >> * Rename *gcc_retain* to *gnu_retain* > >> >> --- > >> >> config.h.in | 3 +++ > >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > >> >> configure.ac | 21 +++++++++++++++ > >> >> include/libc-symbols.h | 14 +++++++--- > >> >> libio/Makefile | 32 +++++++++++++++++++++++ > >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > >> >> libio/tst-cleanup.exp | 1 + > >> >> 7 files changed, 159 insertions(+), 4 deletions(-) > >> >> create mode 100644 libio/tst-cleanup.c > >> >> create mode 100644 libio/tst-cleanup.exp > >> >> > >> >> diff --git a/config.h.in b/config.h.in > >> >> index ca1547ae67..96a08c7757 100644 > >> >> --- a/config.h.in > >> >> +++ b/config.h.in > >> >> @@ -187,6 +187,9 @@ > >> >> /* Define if gcc supports attribute ifunc. */ > >> >> #undef HAVE_GCC_IFUNC > >> >> > >> >> +/* Define if CC supports attribute retain. */ > >> >> +#undef HAVE_GNU_RETAIN > >> >> + > >> >> /* Define if the linker defines __ehdr_start. */ > >> >> #undef HAVE_EHDR_START > >> >> > >> >> diff --git a/configure b/configure > >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> --- a/configure > >> >> +++ b/configure > >> >> @@ -4105,6 +4105,31 @@ fi > >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> > >> >> > >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> + $as_echo_n "(cached) " >&6 > >> >> +else > >> >> + cat > conftest.c <<EOF > >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> +EOF > >> >> +libc_cv_gnu_retain=no > >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> + 2>&5 ; then > >> >> + libc_cv_gnu_retain=yes > >> >> +fi > >> >> +rm -f conftest* > >> >> +fi > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> + > >> >> +fi > >> >> +config_vars="$config_vars > >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> + > >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> @@ -5871,6 +5896,40 @@ fi > >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> > >> >> > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> +libc_linker_feature=no > >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> + if test -n "$libc_linker_check"; then > >> >> + cat > conftest.c <<EOF > >> >> +int _start (void) { return 42; } > >> >> +EOF > >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> + 1>&5' > >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> + (eval $ac_try) 2>&5 > >> >> + ac_status=$? > >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> + test $ac_status = 0; }; } > >> >> + then > >> >> + libc_linker_feature=yes > >> >> + fi > >> >> + rm -f conftest* > >> >> + fi > >> >> +fi > >> >> +if test $libc_linker_feature = yes; then > >> >> + libc_cv_z_start_stop_gc=yes > >> >> +else > >> >> + libc_cv_z_start_stop_gc=no > >> >> +fi > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> +config_vars="$config_vars > >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> + > >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> libc_linker_feature=no > >> >> diff --git a/configure.ac b/configure.ac > >> >> index fce967f2c2..cc47e56e82 100644 > >> >> --- a/configure.ac > >> >> +++ b/configure.ac > >> >> @@ -707,6 +707,23 @@ fi > >> >> rm -f conftest*]) > >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> > >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> + libc_cv_gnu_retain, [dnl > >> >> +cat > conftest.c <<EOF > >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> +EOF > >> >> +libc_cv_gnu_retain=no > >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> + libc_cv_gnu_retain=yes > >> >> +fi > >> >> +rm -f conftest*]) > >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> +fi > >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> + > >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> AC_SUBST(libc_cv_z_execstack) > >> >> > >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> + > >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> [-Wl,--no-dynamic-linker], > >> >> [libc_cv_no_dynamic_linker=yes], > >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> index 546fc26a7b..127ea656c2 100644 > >> >> --- a/include/libc-symbols.h > >> >> +++ b/include/libc-symbols.h > >> >> @@ -352,6 +352,12 @@ for linking") > >> >> > >> >> */ > >> >> > >> >> +#ifdef HAVE_GNU_RETAIN > >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> +#else > >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> +#endif > >> >> + > >> >> /* Symbol set support macros. */ > >> >> > >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> @@ -367,12 +373,12 @@ for linking") > >> >> /* When building a shared library, make the set section writable, > >> >> because it will need to be relocated at run time anyway. */ > >> >> # define _elf_set_element(set, symbol) \ > >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> #else > >> >> # define _elf_set_element(set, symbol) \ > >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> #endif > >> >> > >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> index 12ce41038f..c9c232ebc2 100644 > >> >> --- a/libio/Makefile > >> >> +++ b/libio/Makefile > >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> $(objpfx)tst-bz24228-mem.out > >> >> endif > >> >> + > >> >> +tests += tst-cleanup-default > >> >> +tests-static += tst-cleanup-default > >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >> > > >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > >> > >> Added. > >> > >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> + > >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >> > > >> >Same here. > >> > >> Added. > >> > >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > >> >> +endif > >> >> endif > >> >> > >> >> include ../Rules > >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> endif > >> >> > >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> + > >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> + > >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> > >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> $(common-objpfx)libio/; \ > >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > >> >> new file mode 100644 > >> >> index 0000000000..7f0a34a91e > >> >> --- /dev/null > >> >> +++ b/libio/tst-cleanup.c > >> >> @@ -0,0 +1,33 @@ > >> > > >> >Please add a comment saying that test --gc-sections. > >> > >> OK, added. > >> > >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. > >> >> + This file is part of the GNU C Library. > >> >> + > >> >> + The GNU C Library is free software; you can redistribute it and/or > >> >> + modify it under the terms of the GNU Lesser General Public > >> >> + License as published by the Free Software Foundation; either > >> >> + version 2.1 of the License, or (at your option) any later version. > >> >> + > >> >> + The GNU C Library is distributed in the hope that it will be useful, > >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of > >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > >> >> + Lesser General Public License for more details. > >> >> + > >> >> + You should have received a copy of the GNU Lesser General Public > >> >> + License along with the GNU C Library; if not, see > >> >> + <https://www.gnu.org/licenses/>. */ > >> >> + > >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ > >> >> + > >> >> +#include <stdio.h> > >> >> +#include <stdlib.h> > >> >> + > >> >> +void > >> >> +hook (void) > >> >> +{ > >> >> + puts ("hello"); > >> >> +} > >> >> + > >> >> +int > >> >> +main (void) > >> >> +{ > >> >> + atexit (hook); > >> >> +} > >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > >> >> new file mode 100644 > >> >> index 0000000000..ce01362503 > >> >> --- /dev/null > >> >> +++ b/libio/tst-cleanup.exp > >> >> @@ -0,0 +1 @@ > >> >> +hello > >> >> -- > >> >> 2.31.0.291.g576ba9dcdaf-goog > >> >> > >> > > >> > >> diff --git a/config.h.in b/config.h.in > >> index ca1547ae67..96a08c7757 100644 > >> --- a/config.h.in > >> +++ b/config.h.in > >> @@ -187,6 +187,9 @@ > >> /* Define if gcc supports attribute ifunc. */ > >> #undef HAVE_GCC_IFUNC > >> > >> +/* Define if CC supports attribute retain. */ > >> +#undef HAVE_GNU_RETAIN > >> + > >> /* Define if the linker defines __ehdr_start. */ > >> #undef HAVE_EHDR_START > >> > >> diff --git a/configure b/configure > >> index fcf43bf7de..e64b7f8efe 100755 > >> --- a/configure > >> +++ b/configure > >> @@ -4105,6 +4105,31 @@ fi > >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> > >> > >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> +if ${libc_cv_gnu_retain+:} false; then : > >> + $as_echo_n "(cached) " >&6 > >> +else > >> + cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gnu_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> + 2>&5 ; then > >> + libc_cv_gnu_retain=yes > >> +fi > >> +rm -f conftest* > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> +if test $libc_cv_gnu_retain = yes; then > >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> + > >> +fi > >> +config_vars="$config_vars > >> +have-gnu-retain = $libc_cv_gnu_retain" > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> @@ -5871,6 +5896,40 @@ fi > >> $as_echo "$libc_linker_feature" >&6; } > >> > >> > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> +libc_linker_feature=no > >> +if test x"$gnu_ld" = x"yes"; then > >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> + if test -n "$libc_linker_check"; then > >> + cat > conftest.c <<EOF > >> +int _start (void) { return 42; } > >> +EOF > >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> + -fPIC -shared -o conftest.so conftest.c > >> + 1>&5' > >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> + (eval $ac_try) 2>&5 > >> + ac_status=$? > >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> + test $ac_status = 0; }; } > >> + then > >> + libc_linker_feature=yes > >> + fi > >> + rm -f conftest* > >> + fi > >> +fi > >> +if test $libc_linker_feature = yes; then > >> + libc_cv_z_start_stop_gc=yes > >> +else > >> + libc_cv_z_start_stop_gc=no > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> +$as_echo "$libc_linker_feature" >&6; } > >> +config_vars="$config_vars > >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> + > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> libc_linker_feature=no > >> diff --git a/configure.ac b/configure.ac > >> index fce967f2c2..cc47e56e82 100644 > >> --- a/configure.ac > >> +++ b/configure.ac > >> @@ -707,6 +707,23 @@ fi > >> rm -f conftest*]) > >> AC_SUBST(libc_cv_textrel_ifunc) > >> > >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> + libc_cv_gnu_retain, [dnl > >> +cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gnu_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> + 2>&AS_MESSAGE_LOG_FD ; then > >> + libc_cv_gnu_retain=yes > >> +fi > >> +rm -f conftest*]) > >> +if test $libc_cv_gnu_retain = yes; then > >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> +fi > >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> libc_cv_gcc_incompatible_alias, [dnl > >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> AC_SUBST(libc_cv_z_execstack) > >> > >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> + > >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> [-Wl,--no-dynamic-linker], > >> [libc_cv_no_dynamic_linker=yes], > >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> index 546fc26a7b..127ea656c2 100644 > >> --- a/include/libc-symbols.h > >> +++ b/include/libc-symbols.h > >> @@ -352,6 +352,12 @@ for linking") > >> > >> */ > >> > >> +#ifdef HAVE_GNU_RETAIN > >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> +#else > >> +# define attribute_used_retain __attribute__ ((__used__)) > >> +#endif > >> + > >> /* Symbol set support macros. */ > >> > >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> @@ -367,12 +373,12 @@ for linking") > >> /* When building a shared library, make the set section writable, > >> because it will need to be relocated at run time anyway. */ > >> # define _elf_set_element(set, symbol) \ > >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #else > >> # define _elf_set_element(set, symbol) \ > >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #endif > >> > >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> diff --git a/libio/Makefile b/libio/Makefile > >> index 12ce41038f..ad0d53bb49 100644 > >> --- a/libio/Makefile > >> +++ b/libio/Makefile > >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> $(objpfx)tst-bz24228-mem.out > >> endif > >> + > >> +tests += tst-cleanup-default tst-cleanup-default-static > >> +tests-static += tst-cleanup-default-static > >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> + > >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> +endif > >> endif > >> > >> include ../Rules > >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> endif > >> > >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> + > >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > >> + $(compile.c) -o $@ > > > >Please add a separate .c file for each test to get the correct dependency. > > Changed this block to: > > @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-default.c: tst-cleanup.c > + cp $< $@ > +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c > + cp $< $@ > + > +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c > + cp $< $@ > + > +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c > + cp $< $@ > +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c > + cp $< $@ > + > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ > "make clean" doesn't remove the generated files. The standard way in glibc is to add a *-static.c source. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-03 20:47 ` H.J. Lu @ 2021-04-03 21:57 ` Fangrui Song 2021-04-05 1:55 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-04-03 21:57 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-04-03, H.J. Lu wrote: >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: >> >> >> On 2021-04-02, H.J. Lu wrote: >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> On 2021-04-01, H.J. Lu wrote: >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined >> >> >> variables will be retained by the linker. >> >> >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> >> >> will not be optimized out; 'retain' prevents section garbage collection >> >> >> if the linker support SHF_GNU_RETAIN. >> >> >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> >> >> identifier name sections to be GCed even if there are live >> >> >> __start_/__stop_ references. >> >> >> >> >> >> Without the change, there are some static linking problems, e.g. >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> >> >> stdout is not flushed on exit. >> >> >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> >> >> --- >> >> >> Changes in v1 -> v2: >> >> >> * Define attribute_used_retain_section >> >> >> Changes in v2 -> v3: >> >> >> * Use attribute_used_retain instead attribute_used_retain_section >> >> >> Changes in v3 -> v4: >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests >> >> >> Changes in v4 -> v5: >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported >> >> >> * Rename *gcc_retain* to *gnu_retain* >> >> >> --- >> >> >> config.h.in | 3 +++ >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ >> >> >> configure.ac | 21 +++++++++++++++ >> >> >> include/libc-symbols.h | 14 +++++++--- >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ >> >> >> libio/tst-cleanup.exp | 1 + >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) >> >> >> create mode 100644 libio/tst-cleanup.c >> >> >> create mode 100644 libio/tst-cleanup.exp >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> >> index ca1547ae67..96a08c7757 100644 >> >> >> --- a/config.h.in >> >> >> +++ b/config.h.in >> >> >> @@ -187,6 +187,9 @@ >> >> >> /* Define if gcc supports attribute ifunc. */ >> >> >> #undef HAVE_GCC_IFUNC >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> >> +#undef HAVE_GNU_RETAIN >> >> >> + >> >> >> /* Define if the linker defines __ehdr_start. */ >> >> >> #undef HAVE_EHDR_START >> >> >> >> >> >> diff --git a/configure b/configure >> >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> >> --- a/configure >> >> >> +++ b/configure >> >> >> @@ -4105,6 +4105,31 @@ fi >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> >> + $as_echo_n "(cached) " >&6 >> >> >> +else >> >> >> + cat > conftest.c <<EOF >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> +EOF >> >> >> +libc_cv_gnu_retain=no >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> >> + 2>&5 ; then >> >> >> + libc_cv_gnu_retain=yes >> >> >> +fi >> >> >> +rm -f conftest* >> >> >> +fi >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> >> + >> >> >> +fi >> >> >> +config_vars="$config_vars >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> >> + >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> >> @@ -5871,6 +5896,40 @@ fi >> >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> >> +libc_linker_feature=no >> >> >> +if test x"$gnu_ld" = x"yes"; then >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> >> + if test -n "$libc_linker_check"; then >> >> >> + cat > conftest.c <<EOF >> >> >> +int _start (void) { return 42; } >> >> >> +EOF >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> >> + -fPIC -shared -o conftest.so conftest.c >> >> >> + 1>&5' >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> >> + (eval $ac_try) 2>&5 >> >> >> + ac_status=$? >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> >> + test $ac_status = 0; }; } >> >> >> + then >> >> >> + libc_linker_feature=yes >> >> >> + fi >> >> >> + rm -f conftest* >> >> >> + fi >> >> >> +fi >> >> >> +if test $libc_linker_feature = yes; then >> >> >> + libc_cv_z_start_stop_gc=yes >> >> >> +else >> >> >> + libc_cv_z_start_stop_gc=no >> >> >> +fi >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> >> +config_vars="$config_vars >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> >> + >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> >> libc_linker_feature=no >> >> >> diff --git a/configure.ac b/configure.ac >> >> >> index fce967f2c2..cc47e56e82 100644 >> >> >> --- a/configure.ac >> >> >> +++ b/configure.ac >> >> >> @@ -707,6 +707,23 @@ fi >> >> >> rm -f conftest*]) >> >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> >> + libc_cv_gnu_retain, [dnl >> >> >> +cat > conftest.c <<EOF >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> +EOF >> >> >> +libc_cv_gnu_retain=no >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> >> + libc_cv_gnu_retain=yes >> >> >> +fi >> >> >> +rm -f conftest*]) >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> >> +fi >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> >> + >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> >> + >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> >> [-Wl,--no-dynamic-linker], >> >> >> [libc_cv_no_dynamic_linker=yes], >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> >> index 546fc26a7b..127ea656c2 100644 >> >> >> --- a/include/libc-symbols.h >> >> >> +++ b/include/libc-symbols.h >> >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> >> >> */ >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> >> +#else >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> >> +#endif >> >> >> + >> >> >> /* Symbol set support macros. */ >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> >> @@ -367,12 +373,12 @@ for linking") >> >> >> /* When building a shared library, make the set section writable, >> >> >> because it will need to be relocated at run time anyway. */ >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> #else >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> #endif >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> >> index 12ce41038f..c9c232ebc2 100644 >> >> >> --- a/libio/Makefile >> >> >> +++ b/libio/Makefile >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> >> $(objpfx)tst-bz24228-mem.out >> >> >> endif >> >> >> + >> >> >> +tests += tst-cleanup-default >> >> >> +tests-static += tst-cleanup-default >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out >> >> > >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. >> >> >> >> Added. >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> >> + >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out >> >> > >> >> >Same here. >> >> >> >> Added. >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> +endif >> >> >> endif >> >> >> >> >> >> include ../Rules >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> endif >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> >> + $(compile.c) -o $@ >> >> >> + >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> >> + $(compile.c) -o $@ >> >> >> + >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> >> >> + $(compile.c) -o $@ >> >> >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> >> $(common-objpfx)libio/; \ >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> >> >> new file mode 100644 >> >> >> index 0000000000..7f0a34a91e >> >> >> --- /dev/null >> >> >> +++ b/libio/tst-cleanup.c >> >> >> @@ -0,0 +1,33 @@ >> >> > >> >> >Please add a comment saying that test --gc-sections. >> >> >> >> OK, added. >> >> >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> >> >> + This file is part of the GNU C Library. >> >> >> + >> >> >> + The GNU C Library is free software; you can redistribute it and/or >> >> >> + modify it under the terms of the GNU Lesser General Public >> >> >> + License as published by the Free Software Foundation; either >> >> >> + version 2.1 of the License, or (at your option) any later version. >> >> >> + >> >> >> + The GNU C Library is distributed in the hope that it will be useful, >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> >> >> + Lesser General Public License for more details. >> >> >> + >> >> >> + You should have received a copy of the GNU Lesser General Public >> >> >> + License along with the GNU C Library; if not, see >> >> >> + <https://www.gnu.org/licenses/>. */ >> >> >> + >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> >> >> + >> >> >> +#include <stdio.h> >> >> >> +#include <stdlib.h> >> >> >> + >> >> >> +void >> >> >> +hook (void) >> >> >> +{ >> >> >> + puts ("hello"); >> >> >> +} >> >> >> + >> >> >> +int >> >> >> +main (void) >> >> >> +{ >> >> >> + atexit (hook); >> >> >> +} >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> >> >> new file mode 100644 >> >> >> index 0000000000..ce01362503 >> >> >> --- /dev/null >> >> >> +++ b/libio/tst-cleanup.exp >> >> >> @@ -0,0 +1 @@ >> >> >> +hello >> >> >> -- >> >> >> 2.31.0.291.g576ba9dcdaf-goog >> >> >> >> >> > >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> index ca1547ae67..96a08c7757 100644 >> >> --- a/config.h.in >> >> +++ b/config.h.in >> >> @@ -187,6 +187,9 @@ >> >> /* Define if gcc supports attribute ifunc. */ >> >> #undef HAVE_GCC_IFUNC >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> +#undef HAVE_GNU_RETAIN >> >> + >> >> /* Define if the linker defines __ehdr_start. */ >> >> #undef HAVE_EHDR_START >> >> >> >> diff --git a/configure b/configure >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> --- a/configure >> >> +++ b/configure >> >> @@ -4105,6 +4105,31 @@ fi >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> + $as_echo_n "(cached) " >&6 >> >> +else >> >> + cat > conftest.c <<EOF >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> +EOF >> >> +libc_cv_gnu_retain=no >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> + 2>&5 ; then >> >> + libc_cv_gnu_retain=yes >> >> +fi >> >> +rm -f conftest* >> >> +fi >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> +if test $libc_cv_gnu_retain = yes; then >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> + >> >> +fi >> >> +config_vars="$config_vars >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> + >> >> # Check if gcc warns about alias for function with incompatible types. >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> @@ -5871,6 +5896,40 @@ fi >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> +libc_linker_feature=no >> >> +if test x"$gnu_ld" = x"yes"; then >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> + if test -n "$libc_linker_check"; then >> >> + cat > conftest.c <<EOF >> >> +int _start (void) { return 42; } >> >> +EOF >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> + -fPIC -shared -o conftest.so conftest.c >> >> + 1>&5' >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> + (eval $ac_try) 2>&5 >> >> + ac_status=$? >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> + test $ac_status = 0; }; } >> >> + then >> >> + libc_linker_feature=yes >> >> + fi >> >> + rm -f conftest* >> >> + fi >> >> +fi >> >> +if test $libc_linker_feature = yes; then >> >> + libc_cv_z_start_stop_gc=yes >> >> +else >> >> + libc_cv_z_start_stop_gc=no >> >> +fi >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> +config_vars="$config_vars >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> + >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> libc_linker_feature=no >> >> diff --git a/configure.ac b/configure.ac >> >> index fce967f2c2..cc47e56e82 100644 >> >> --- a/configure.ac >> >> +++ b/configure.ac >> >> @@ -707,6 +707,23 @@ fi >> >> rm -f conftest*]) >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> + libc_cv_gnu_retain, [dnl >> >> +cat > conftest.c <<EOF >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> +EOF >> >> +libc_cv_gnu_retain=no >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> + libc_cv_gnu_retain=yes >> >> +fi >> >> +rm -f conftest*]) >> >> +if test $libc_cv_gnu_retain = yes; then >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> +fi >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> + >> >> # Check if gcc warns about alias for function with incompatible types. >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> + >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> [-Wl,--no-dynamic-linker], >> >> [libc_cv_no_dynamic_linker=yes], >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> index 546fc26a7b..127ea656c2 100644 >> >> --- a/include/libc-symbols.h >> >> +++ b/include/libc-symbols.h >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> */ >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> +#else >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> +#endif >> >> + >> >> /* Symbol set support macros. */ >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> @@ -367,12 +373,12 @@ for linking") >> >> /* When building a shared library, make the set section writable, >> >> because it will need to be relocated at run time anyway. */ >> >> # define _elf_set_element(set, symbol) \ >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> #else >> >> # define _elf_set_element(set, symbol) \ >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> #endif >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> index 12ce41038f..ad0d53bb49 100644 >> >> --- a/libio/Makefile >> >> +++ b/libio/Makefile >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> $(objpfx)tst-bz24228-mem.out >> >> endif >> >> + >> >> +tests += tst-cleanup-default tst-cleanup-default-static >> >> +tests-static += tst-cleanup-default-static >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections >> >> + >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc >> >> +endif >> >> endif >> >> >> >> include ../Rules >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> endif >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> + >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> > >> >Please add a separate .c file for each test to get the correct dependency. >> >> Changed this block to: >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> endif >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c >> + cp $< $@ >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c >> + cp $< $@ >> + >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c >> + cp $< $@ >> + >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c >> + cp $< $@ >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c >> + cp $< $@ >> + >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> $(common-objpfx)libio/; \ >> > >"make clean" doesn't remove the generated files. The standard way in glibc >is to add a *-static.c source. I'll use .INTERMEDIATE and $(eval $(call ..)) diff --git a/libio/Makefile b/libio/Makefile index 12ce41038f..a9b44f04df 100644 --- a/libio/Makefile +++ b/libio/Makefile @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ $(objpfx)tst-bz24228-mem.out endif + +tests += tst-cleanup-default tst-cleanup-default-static +tests-static += tst-cleanup-default-static +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections + +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc +endif endif include ../Rules @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) $(objpfx)tst-wfile-sync.out: $(gen-locales) endif +define gen-tst-cleanup +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out + cmp $$^ > $$@; $$(evaluate-test) +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c + cp $$< $$@ +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c +endef + +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ + $(eval $(call gen-tst-cleanup,$(t)))) + $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ $(common-objpfx)libio/; \ ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-03 21:57 ` Fangrui Song @ 2021-04-05 1:55 ` H.J. Lu 2021-04-05 18:17 ` Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-04-05 1:55 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song <maskray@google.com> wrote: > > On 2021-04-03, H.J. Lu wrote: > >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: > >> > >> > >> On 2021-04-02, H.J. Lu wrote: > >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: > >> >> > >> >> On 2021-04-01, H.J. Lu wrote: > >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> > >> >> >> So that text_set_element/data_set_element/bss_set_element defined > >> >> >> variables will be retained by the linker. > >> >> >> > >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> >> >> will not be optimized out; 'retain' prevents section garbage collection > >> >> >> if the linker support SHF_GNU_RETAIN. > >> >> >> > >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> >> >> identifier name sections to be GCed even if there are live > >> >> >> __start_/__stop_ references. > >> >> >> > >> >> >> Without the change, there are some static linking problems, e.g. > >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> >> >> stdout is not flushed on exit. > >> >> >> > >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> >> >> --- > >> >> >> Changes in v1 -> v2: > >> >> >> * Define attribute_used_retain_section > >> >> >> Changes in v2 -> v3: > >> >> >> * Use attribute_used_retain instead attribute_used_retain_section > >> >> >> Changes in v3 -> v4: > >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> >> >> Changes in v4 -> v5: > >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > >> >> >> * Rename *gcc_retain* to *gnu_retain* > >> >> >> --- > >> >> >> config.h.in | 3 +++ > >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > >> >> >> configure.ac | 21 +++++++++++++++ > >> >> >> include/libc-symbols.h | 14 +++++++--- > >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ > >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > >> >> >> libio/tst-cleanup.exp | 1 + > >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) > >> >> >> create mode 100644 libio/tst-cleanup.c > >> >> >> create mode 100644 libio/tst-cleanup.exp > >> >> >> > >> >> >> diff --git a/config.h.in b/config.h.in > >> >> >> index ca1547ae67..96a08c7757 100644 > >> >> >> --- a/config.h.in > >> >> >> +++ b/config.h.in > >> >> >> @@ -187,6 +187,9 @@ > >> >> >> /* Define if gcc supports attribute ifunc. */ > >> >> >> #undef HAVE_GCC_IFUNC > >> >> >> > >> >> >> +/* Define if CC supports attribute retain. */ > >> >> >> +#undef HAVE_GNU_RETAIN > >> >> >> + > >> >> >> /* Define if the linker defines __ehdr_start. */ > >> >> >> #undef HAVE_EHDR_START > >> >> >> > >> >> >> diff --git a/configure b/configure > >> >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> >> --- a/configure > >> >> >> +++ b/configure > >> >> >> @@ -4105,6 +4105,31 @@ fi > >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> >> > >> >> >> > >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> >> + $as_echo_n "(cached) " >&6 > >> >> >> +else > >> >> >> + cat > conftest.c <<EOF > >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> +EOF > >> >> >> +libc_cv_gnu_retain=no > >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> >> + 2>&5 ; then > >> >> >> + libc_cv_gnu_retain=yes > >> >> >> +fi > >> >> >> +rm -f conftest* > >> >> >> +fi > >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> >> + > >> >> >> +fi > >> >> >> +config_vars="$config_vars > >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> >> + > >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> >> @@ -5871,6 +5896,40 @@ fi > >> >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> >> > >> >> >> > >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> >> +libc_linker_feature=no > >> >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> >> + if test -n "$libc_linker_check"; then > >> >> >> + cat > conftest.c <<EOF > >> >> >> +int _start (void) { return 42; } > >> >> >> +EOF > >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> >> + 1>&5' > >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> >> + (eval $ac_try) 2>&5 > >> >> >> + ac_status=$? > >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> >> + test $ac_status = 0; }; } > >> >> >> + then > >> >> >> + libc_linker_feature=yes > >> >> >> + fi > >> >> >> + rm -f conftest* > >> >> >> + fi > >> >> >> +fi > >> >> >> +if test $libc_linker_feature = yes; then > >> >> >> + libc_cv_z_start_stop_gc=yes > >> >> >> +else > >> >> >> + libc_cv_z_start_stop_gc=no > >> >> >> +fi > >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> >> +config_vars="$config_vars > >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> >> + > >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> >> libc_linker_feature=no > >> >> >> diff --git a/configure.ac b/configure.ac > >> >> >> index fce967f2c2..cc47e56e82 100644 > >> >> >> --- a/configure.ac > >> >> >> +++ b/configure.ac > >> >> >> @@ -707,6 +707,23 @@ fi > >> >> >> rm -f conftest*]) > >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> >> > >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> >> + libc_cv_gnu_retain, [dnl > >> >> >> +cat > conftest.c <<EOF > >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> +EOF > >> >> >> +libc_cv_gnu_retain=no > >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> >> + libc_cv_gnu_retain=yes > >> >> >> +fi > >> >> >> +rm -f conftest*]) > >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> >> +fi > >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> >> + > >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> >> AC_SUBST(libc_cv_z_execstack) > >> >> >> > >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> >> + > >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> >> [-Wl,--no-dynamic-linker], > >> >> >> [libc_cv_no_dynamic_linker=yes], > >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> >> index 546fc26a7b..127ea656c2 100644 > >> >> >> --- a/include/libc-symbols.h > >> >> >> +++ b/include/libc-symbols.h > >> >> >> @@ -352,6 +352,12 @@ for linking") > >> >> >> > >> >> >> */ > >> >> >> > >> >> >> +#ifdef HAVE_GNU_RETAIN > >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> >> +#else > >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> >> +#endif > >> >> >> + > >> >> >> /* Symbol set support macros. */ > >> >> >> > >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> >> @@ -367,12 +373,12 @@ for linking") > >> >> >> /* When building a shared library, make the set section writable, > >> >> >> because it will need to be relocated at run time anyway. */ > >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> #else > >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> #endif > >> >> >> > >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> index 12ce41038f..c9c232ebc2 100644 > >> >> >> --- a/libio/Makefile > >> >> >> +++ b/libio/Makefile > >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> endif > >> >> >> + > >> >> >> +tests += tst-cleanup-default > >> >> >> +tests-static += tst-cleanup-default > >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >> >> > > >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > >> >> > >> >> Added. > >> >> > >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> + > >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >> >> > > >> >> >Same here. > >> >> > >> >> Added. > >> >> > >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> +endif > >> >> >> endif > >> >> >> > >> >> >> include ../Rules > >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> endif > >> >> >> > >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> >> + $(compile.c) -o $@ > >> >> >> + > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> + $(compile.c) -o $@ > >> >> >> + > >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > >> >> >> + $(compile.c) -o $@ > >> >> >> > >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> $(common-objpfx)libio/; \ > >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > >> >> >> new file mode 100644 > >> >> >> index 0000000000..7f0a34a91e > >> >> >> --- /dev/null > >> >> >> +++ b/libio/tst-cleanup.c > >> >> >> @@ -0,0 +1,33 @@ > >> >> > > >> >> >Please add a comment saying that test --gc-sections. > >> >> > >> >> OK, added. > >> >> > >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. > >> >> >> + This file is part of the GNU C Library. > >> >> >> + > >> >> >> + The GNU C Library is free software; you can redistribute it and/or > >> >> >> + modify it under the terms of the GNU Lesser General Public > >> >> >> + License as published by the Free Software Foundation; either > >> >> >> + version 2.1 of the License, or (at your option) any later version. > >> >> >> + > >> >> >> + The GNU C Library is distributed in the hope that it will be useful, > >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of > >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > >> >> >> + Lesser General Public License for more details. > >> >> >> + > >> >> >> + You should have received a copy of the GNU Lesser General Public > >> >> >> + License along with the GNU C Library; if not, see > >> >> >> + <https://www.gnu.org/licenses/>. */ > >> >> >> + > >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ > >> >> >> + > >> >> >> +#include <stdio.h> > >> >> >> +#include <stdlib.h> > >> >> >> + > >> >> >> +void > >> >> >> +hook (void) > >> >> >> +{ > >> >> >> + puts ("hello"); > >> >> >> +} > >> >> >> + > >> >> >> +int > >> >> >> +main (void) > >> >> >> +{ > >> >> >> + atexit (hook); > >> >> >> +} > >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > >> >> >> new file mode 100644 > >> >> >> index 0000000000..ce01362503 > >> >> >> --- /dev/null > >> >> >> +++ b/libio/tst-cleanup.exp > >> >> >> @@ -0,0 +1 @@ > >> >> >> +hello > >> >> >> -- > >> >> >> 2.31.0.291.g576ba9dcdaf-goog > >> >> >> > >> >> > > >> >> > >> >> diff --git a/config.h.in b/config.h.in > >> >> index ca1547ae67..96a08c7757 100644 > >> >> --- a/config.h.in > >> >> +++ b/config.h.in > >> >> @@ -187,6 +187,9 @@ > >> >> /* Define if gcc supports attribute ifunc. */ > >> >> #undef HAVE_GCC_IFUNC > >> >> > >> >> +/* Define if CC supports attribute retain. */ > >> >> +#undef HAVE_GNU_RETAIN > >> >> + > >> >> /* Define if the linker defines __ehdr_start. */ > >> >> #undef HAVE_EHDR_START > >> >> > >> >> diff --git a/configure b/configure > >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> --- a/configure > >> >> +++ b/configure > >> >> @@ -4105,6 +4105,31 @@ fi > >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> > >> >> > >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> + $as_echo_n "(cached) " >&6 > >> >> +else > >> >> + cat > conftest.c <<EOF > >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> +EOF > >> >> +libc_cv_gnu_retain=no > >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> + 2>&5 ; then > >> >> + libc_cv_gnu_retain=yes > >> >> +fi > >> >> +rm -f conftest* > >> >> +fi > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> + > >> >> +fi > >> >> +config_vars="$config_vars > >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> + > >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> @@ -5871,6 +5896,40 @@ fi > >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> > >> >> > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> +libc_linker_feature=no > >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> + if test -n "$libc_linker_check"; then > >> >> + cat > conftest.c <<EOF > >> >> +int _start (void) { return 42; } > >> >> +EOF > >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> + 1>&5' > >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> + (eval $ac_try) 2>&5 > >> >> + ac_status=$? > >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> + test $ac_status = 0; }; } > >> >> + then > >> >> + libc_linker_feature=yes > >> >> + fi > >> >> + rm -f conftest* > >> >> + fi > >> >> +fi > >> >> +if test $libc_linker_feature = yes; then > >> >> + libc_cv_z_start_stop_gc=yes > >> >> +else > >> >> + libc_cv_z_start_stop_gc=no > >> >> +fi > >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> +config_vars="$config_vars > >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> + > >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> libc_linker_feature=no > >> >> diff --git a/configure.ac b/configure.ac > >> >> index fce967f2c2..cc47e56e82 100644 > >> >> --- a/configure.ac > >> >> +++ b/configure.ac > >> >> @@ -707,6 +707,23 @@ fi > >> >> rm -f conftest*]) > >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> > >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> + libc_cv_gnu_retain, [dnl > >> >> +cat > conftest.c <<EOF > >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> +EOF > >> >> +libc_cv_gnu_retain=no > >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> + libc_cv_gnu_retain=yes > >> >> +fi > >> >> +rm -f conftest*]) > >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> +fi > >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> + > >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> AC_SUBST(libc_cv_z_execstack) > >> >> > >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> + > >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> [-Wl,--no-dynamic-linker], > >> >> [libc_cv_no_dynamic_linker=yes], > >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> index 546fc26a7b..127ea656c2 100644 > >> >> --- a/include/libc-symbols.h > >> >> +++ b/include/libc-symbols.h > >> >> @@ -352,6 +352,12 @@ for linking") > >> >> > >> >> */ > >> >> > >> >> +#ifdef HAVE_GNU_RETAIN > >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> +#else > >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> +#endif > >> >> + > >> >> /* Symbol set support macros. */ > >> >> > >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> @@ -367,12 +373,12 @@ for linking") > >> >> /* When building a shared library, make the set section writable, > >> >> because it will need to be relocated at run time anyway. */ > >> >> # define _elf_set_element(set, symbol) \ > >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> #else > >> >> # define _elf_set_element(set, symbol) \ > >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> #endif > >> >> > >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> index 12ce41038f..ad0d53bb49 100644 > >> >> --- a/libio/Makefile > >> >> +++ b/libio/Makefile > >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> $(objpfx)tst-bz24228-mem.out > >> >> endif > >> >> + > >> >> +tests += tst-cleanup-default tst-cleanup-default-static > >> >> +tests-static += tst-cleanup-default-static > >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> >> + > >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> +endif > >> >> endif > >> >> > >> >> include ../Rules > >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> endif > >> >> > >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> + > >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> > > >> >Please add a separate .c file for each test to get the correct dependency. > >> > >> Changed this block to: > >> > >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> endif > >> > >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c > >> + cp $< $@ > >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c > >> + cp $< $@ > >> + > >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> + $(compile.c) -o $@ > >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c > >> + cp $< $@ > >> + > >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c > >> + cp $< $@ > >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out > >> + cmp $^ > $@; \ > >> + $(evaluate-test) > >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c > >> + cp $< $@ > >> + > >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> $(common-objpfx)libio/; \ > >> > > > >"make clean" doesn't remove the generated files. The standard way in glibc > >is to add a *-static.c source. > > I'll use .INTERMEDIATE and $(eval $(call ..)) > > diff --git a/libio/Makefile b/libio/Makefile > index 12ce41038f..a9b44f04df 100644 > --- a/libio/Makefile > +++ b/libio/Makefile > @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > $(objpfx)tst-bz24228-mem.out > endif > + > +tests += tst-cleanup-default tst-cleanup-default-static > +tests-static += tst-cleanup-default-static > +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > + > +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > +endif > endif > > include ../Rules > @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +define gen-tst-cleanup > +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out > + cmp $$^ > $$@; $$(evaluate-test) > +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c > + cp $$< $$@ > +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c > +endef > + > +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ > + $(eval $(call gen-tst-cleanup,$(t)))) > + > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ There are 2 issues with static tests: 1. A separate static source is needed. 2. We need to add the static test to both tests and tests-static. If you want to add a separate static source, you can submit a separate patch to address these 2 issues together. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-05 1:55 ` H.J. Lu @ 2021-04-05 18:17 ` Fangrui Song 2021-04-05 20:35 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-04-05 18:17 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-04-04, H.J. Lu wrote: >On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song <maskray@google.com> wrote: >> >> On 2021-04-03, H.J. Lu wrote: >> >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> On 2021-04-02, H.J. Lu wrote: >> >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> On 2021-04-01, H.J. Lu wrote: >> >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined >> >> >> >> variables will be retained by the linker. >> >> >> >> >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> >> >> >> will not be optimized out; 'retain' prevents section garbage collection >> >> >> >> if the linker support SHF_GNU_RETAIN. >> >> >> >> >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> >> >> >> identifier name sections to be GCed even if there are live >> >> >> >> __start_/__stop_ references. >> >> >> >> >> >> >> >> Without the change, there are some static linking problems, e.g. >> >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> >> >> >> stdout is not flushed on exit. >> >> >> >> >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> >> >> >> --- >> >> >> >> Changes in v1 -> v2: >> >> >> >> * Define attribute_used_retain_section >> >> >> >> Changes in v2 -> v3: >> >> >> >> * Use attribute_used_retain instead attribute_used_retain_section >> >> >> >> Changes in v3 -> v4: >> >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests >> >> >> >> Changes in v4 -> v5: >> >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported >> >> >> >> * Rename *gcc_retain* to *gnu_retain* >> >> >> >> --- >> >> >> >> config.h.in | 3 +++ >> >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ >> >> >> >> configure.ac | 21 +++++++++++++++ >> >> >> >> include/libc-symbols.h | 14 +++++++--- >> >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ >> >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ >> >> >> >> libio/tst-cleanup.exp | 1 + >> >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) >> >> >> >> create mode 100644 libio/tst-cleanup.c >> >> >> >> create mode 100644 libio/tst-cleanup.exp >> >> >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> >> >> index ca1547ae67..96a08c7757 100644 >> >> >> >> --- a/config.h.in >> >> >> >> +++ b/config.h.in >> >> >> >> @@ -187,6 +187,9 @@ >> >> >> >> /* Define if gcc supports attribute ifunc. */ >> >> >> >> #undef HAVE_GCC_IFUNC >> >> >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> >> >> +#undef HAVE_GNU_RETAIN >> >> >> >> + >> >> >> >> /* Define if the linker defines __ehdr_start. */ >> >> >> >> #undef HAVE_EHDR_START >> >> >> >> >> >> >> >> diff --git a/configure b/configure >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> >> >> --- a/configure >> >> >> >> +++ b/configure >> >> >> >> @@ -4105,6 +4105,31 @@ fi >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> >> >> + $as_echo_n "(cached) " >&6 >> >> >> >> +else >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> +EOF >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> >> >> + 2>&5 ; then >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> +fi >> >> >> >> +rm -f conftest* >> >> >> >> +fi >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> >> >> + >> >> >> >> +fi >> >> >> >> +config_vars="$config_vars >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> >> >> + >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> >> >> @@ -5871,6 +5896,40 @@ fi >> >> >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> >> >> +libc_linker_feature=no >> >> >> >> +if test x"$gnu_ld" = x"yes"; then >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> >> >> + if test -n "$libc_linker_check"; then >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> +int _start (void) { return 42; } >> >> >> >> +EOF >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> >> >> + -fPIC -shared -o conftest.so conftest.c >> >> >> >> + 1>&5' >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> >> >> + (eval $ac_try) 2>&5 >> >> >> >> + ac_status=$? >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> >> >> + test $ac_status = 0; }; } >> >> >> >> + then >> >> >> >> + libc_linker_feature=yes >> >> >> >> + fi >> >> >> >> + rm -f conftest* >> >> >> >> + fi >> >> >> >> +fi >> >> >> >> +if test $libc_linker_feature = yes; then >> >> >> >> + libc_cv_z_start_stop_gc=yes >> >> >> >> +else >> >> >> >> + libc_cv_z_start_stop_gc=no >> >> >> >> +fi >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> >> >> +config_vars="$config_vars >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> >> >> + >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> >> >> libc_linker_feature=no >> >> >> >> diff --git a/configure.ac b/configure.ac >> >> >> >> index fce967f2c2..cc47e56e82 100644 >> >> >> >> --- a/configure.ac >> >> >> >> +++ b/configure.ac >> >> >> >> @@ -707,6 +707,23 @@ fi >> >> >> >> rm -f conftest*]) >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> >> >> + libc_cv_gnu_retain, [dnl >> >> >> >> +cat > conftest.c <<EOF >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> +EOF >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> +fi >> >> >> >> +rm -f conftest*]) >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> >> >> +fi >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> >> >> + >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> >> >> + >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> >> >> [-Wl,--no-dynamic-linker], >> >> >> >> [libc_cv_no_dynamic_linker=yes], >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> >> >> index 546fc26a7b..127ea656c2 100644 >> >> >> >> --- a/include/libc-symbols.h >> >> >> >> +++ b/include/libc-symbols.h >> >> >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> >> >> >> >> */ >> >> >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> >> >> +#else >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> >> >> +#endif >> >> >> >> + >> >> >> >> /* Symbol set support macros. */ >> >> >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> >> >> @@ -367,12 +373,12 @@ for linking") >> >> >> >> /* When building a shared library, make the set section writable, >> >> >> >> because it will need to be relocated at run time anyway. */ >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> #else >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> #endif >> >> >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> >> >> index 12ce41038f..c9c232ebc2 100644 >> >> >> >> --- a/libio/Makefile >> >> >> >> +++ b/libio/Makefile >> >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> >> >> $(objpfx)tst-bz24228-mem.out >> >> >> >> endif >> >> >> >> + >> >> >> >> +tests += tst-cleanup-default >> >> >> >> +tests-static += tst-cleanup-default >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out >> >> >> > >> >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. >> >> >> >> >> >> Added. >> >> >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> >> >> + >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out >> >> >> > >> >> >> >Same here. >> >> >> >> >> >> Added. >> >> >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> >> +endif >> >> >> >> endif >> >> >> >> >> >> >> >> include ../Rules >> >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> >> endif >> >> >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> >> >> + $(compile.c) -o $@ >> >> >> >> + >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> >> >> + $(compile.c) -o $@ >> >> >> >> + >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> >> >> $(common-objpfx)libio/; \ >> >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> >> >> >> new file mode 100644 >> >> >> >> index 0000000000..7f0a34a91e >> >> >> >> --- /dev/null >> >> >> >> +++ b/libio/tst-cleanup.c >> >> >> >> @@ -0,0 +1,33 @@ >> >> >> > >> >> >> >Please add a comment saying that test --gc-sections. >> >> >> >> >> >> OK, added. >> >> >> >> >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> >> >> >> + This file is part of the GNU C Library. >> >> >> >> + >> >> >> >> + The GNU C Library is free software; you can redistribute it and/or >> >> >> >> + modify it under the terms of the GNU Lesser General Public >> >> >> >> + License as published by the Free Software Foundation; either >> >> >> >> + version 2.1 of the License, or (at your option) any later version. >> >> >> >> + >> >> >> >> + The GNU C Library is distributed in the hope that it will be useful, >> >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> >> >> >> + Lesser General Public License for more details. >> >> >> >> + >> >> >> >> + You should have received a copy of the GNU Lesser General Public >> >> >> >> + License along with the GNU C Library; if not, see >> >> >> >> + <https://www.gnu.org/licenses/>. */ >> >> >> >> + >> >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> >> >> >> + >> >> >> >> +#include <stdio.h> >> >> >> >> +#include <stdlib.h> >> >> >> >> + >> >> >> >> +void >> >> >> >> +hook (void) >> >> >> >> +{ >> >> >> >> + puts ("hello"); >> >> >> >> +} >> >> >> >> + >> >> >> >> +int >> >> >> >> +main (void) >> >> >> >> +{ >> >> >> >> + atexit (hook); >> >> >> >> +} >> >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> >> >> >> new file mode 100644 >> >> >> >> index 0000000000..ce01362503 >> >> >> >> --- /dev/null >> >> >> >> +++ b/libio/tst-cleanup.exp >> >> >> >> @@ -0,0 +1 @@ >> >> >> >> +hello >> >> >> >> -- >> >> >> >> 2.31.0.291.g576ba9dcdaf-goog >> >> >> >> >> >> >> > >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> >> index ca1547ae67..96a08c7757 100644 >> >> >> --- a/config.h.in >> >> >> +++ b/config.h.in >> >> >> @@ -187,6 +187,9 @@ >> >> >> /* Define if gcc supports attribute ifunc. */ >> >> >> #undef HAVE_GCC_IFUNC >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> >> +#undef HAVE_GNU_RETAIN >> >> >> + >> >> >> /* Define if the linker defines __ehdr_start. */ >> >> >> #undef HAVE_EHDR_START >> >> >> >> >> >> diff --git a/configure b/configure >> >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> >> --- a/configure >> >> >> +++ b/configure >> >> >> @@ -4105,6 +4105,31 @@ fi >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> >> + $as_echo_n "(cached) " >&6 >> >> >> +else >> >> >> + cat > conftest.c <<EOF >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> +EOF >> >> >> +libc_cv_gnu_retain=no >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> >> + 2>&5 ; then >> >> >> + libc_cv_gnu_retain=yes >> >> >> +fi >> >> >> +rm -f conftest* >> >> >> +fi >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> >> + >> >> >> +fi >> >> >> +config_vars="$config_vars >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> >> + >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> >> @@ -5871,6 +5896,40 @@ fi >> >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> >> +libc_linker_feature=no >> >> >> +if test x"$gnu_ld" = x"yes"; then >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> >> + if test -n "$libc_linker_check"; then >> >> >> + cat > conftest.c <<EOF >> >> >> +int _start (void) { return 42; } >> >> >> +EOF >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> >> + -fPIC -shared -o conftest.so conftest.c >> >> >> + 1>&5' >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> >> + (eval $ac_try) 2>&5 >> >> >> + ac_status=$? >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> >> + test $ac_status = 0; }; } >> >> >> + then >> >> >> + libc_linker_feature=yes >> >> >> + fi >> >> >> + rm -f conftest* >> >> >> + fi >> >> >> +fi >> >> >> +if test $libc_linker_feature = yes; then >> >> >> + libc_cv_z_start_stop_gc=yes >> >> >> +else >> >> >> + libc_cv_z_start_stop_gc=no >> >> >> +fi >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> >> +config_vars="$config_vars >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> >> + >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> >> libc_linker_feature=no >> >> >> diff --git a/configure.ac b/configure.ac >> >> >> index fce967f2c2..cc47e56e82 100644 >> >> >> --- a/configure.ac >> >> >> +++ b/configure.ac >> >> >> @@ -707,6 +707,23 @@ fi >> >> >> rm -f conftest*]) >> >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> >> + libc_cv_gnu_retain, [dnl >> >> >> +cat > conftest.c <<EOF >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> +EOF >> >> >> +libc_cv_gnu_retain=no >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> >> + libc_cv_gnu_retain=yes >> >> >> +fi >> >> >> +rm -f conftest*]) >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> >> +fi >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> >> + >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> >> + >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> >> [-Wl,--no-dynamic-linker], >> >> >> [libc_cv_no_dynamic_linker=yes], >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> >> index 546fc26a7b..127ea656c2 100644 >> >> >> --- a/include/libc-symbols.h >> >> >> +++ b/include/libc-symbols.h >> >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> >> >> */ >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> >> +#else >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> >> +#endif >> >> >> + >> >> >> /* Symbol set support macros. */ >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> >> @@ -367,12 +373,12 @@ for linking") >> >> >> /* When building a shared library, make the set section writable, >> >> >> because it will need to be relocated at run time anyway. */ >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> #else >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> #endif >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> >> index 12ce41038f..ad0d53bb49 100644 >> >> >> --- a/libio/Makefile >> >> >> +++ b/libio/Makefile >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> >> $(objpfx)tst-bz24228-mem.out >> >> >> endif >> >> >> + >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static >> >> >> +tests-static += tst-cleanup-default-static >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections >> >> >> + >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> +endif >> >> >> endif >> >> >> >> >> >> include ../Rules >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> endif >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> >> + $(compile.c) -o $@ >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c >> >> >> + $(compile.c) -o $@ >> >> >> + >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> >> + $(compile.c) -o $@ >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c >> >> >> + $(compile.c) -o $@ >> >> > >> >> >Please add a separate .c file for each test to get the correct dependency. >> >> >> >> Changed this block to: >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> endif >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c >> >> + cp $< $@ >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c >> >> + cp $< $@ >> >> + >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> + $(compile.c) -o $@ >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c >> >> + cp $< $@ >> >> + >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c >> >> + cp $< $@ >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out >> >> + cmp $^ > $@; \ >> >> + $(evaluate-test) >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c >> >> + cp $< $@ >> >> + >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> $(common-objpfx)libio/; \ >> >> >> > >> >"make clean" doesn't remove the generated files. The standard way in glibc >> >is to add a *-static.c source. >> >> I'll use .INTERMEDIATE and $(eval $(call ..)) >> >> diff --git a/libio/Makefile b/libio/Makefile >> index 12ce41038f..a9b44f04df 100644 >> --- a/libio/Makefile >> +++ b/libio/Makefile >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> $(objpfx)tst-bz24228-mem.out >> endif >> + >> +tests += tst-cleanup-default tst-cleanup-default-static >> +tests-static += tst-cleanup-default-static >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections >> + >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc >> +endif >> endif >> >> include ../Rules >> @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> endif >> >> +define gen-tst-cleanup >> +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out >> + cmp $$^ > $$@; $$(evaluate-test) >> +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c >> + cp $$< $$@ >> +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c >> +endef >> + >> +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ >> + $(eval $(call gen-tst-cleanup,$(t)))) >> + >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> $(common-objpfx)libio/; \ > >There are 2 issues with static tests: > >1. A separate static source is needed. .INTERMEDIATE perfectly solves the lingering copied source issue. I don't see lingering libio/tst-cleanup-*.c >2. We need to add the static test to both tests and tests-static. tests-static suffices. I have checked some tests-static usage in other directories. I have additionally checked that: * touch libc.a => next invocation `make -r -C ~/Dev/glibc/libio objdir=$PWD check -j 20` will rebuild the static tests * touch libc.so => next invocation `make -r -C ~/Dev/glibc/libio objdir=$PWD check -j 20` will rebuild the dynamic tests * rm libio/tst-cleanup-default-cmp.out => next invocation `make -r -C ~/Dev/glibc/libio objdir=$PWD check -j 20` will rerun the single test >If you want to add a separate static source, you can submit a separate patch >to address these 2 issues together. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-05 18:17 ` Fangrui Song @ 2021-04-05 20:35 ` H.J. Lu 2021-04-05 21:03 ` Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-04-05 20:35 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Mon, Apr 5, 2021 at 11:17 AM Fangrui Song <maskray@google.com> wrote: > > On 2021-04-04, H.J. Lu wrote: > >On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song <maskray@google.com> wrote: > >> > >> On 2021-04-03, H.J. Lu wrote: > >> >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: > >> >> > >> >> > >> >> On 2021-04-02, H.J. Lu wrote: > >> >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> > >> >> >> On 2021-04-01, H.J. Lu wrote: > >> >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> >> > >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined > >> >> >> >> variables will be retained by the linker. > >> >> >> >> > >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> >> >> >> will not be optimized out; 'retain' prevents section garbage collection > >> >> >> >> if the linker support SHF_GNU_RETAIN. > >> >> >> >> > >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> >> >> >> identifier name sections to be GCed even if there are live > >> >> >> >> __start_/__stop_ references. > >> >> >> >> > >> >> >> >> Without the change, there are some static linking problems, e.g. > >> >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> >> >> >> stdout is not flushed on exit. > >> >> >> >> > >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> >> >> >> --- > >> >> >> >> Changes in v1 -> v2: > >> >> >> >> * Define attribute_used_retain_section > >> >> >> >> Changes in v2 -> v3: > >> >> >> >> * Use attribute_used_retain instead attribute_used_retain_section > >> >> >> >> Changes in v3 -> v4: > >> >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> >> >> >> Changes in v4 -> v5: > >> >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > >> >> >> >> * Rename *gcc_retain* to *gnu_retain* > >> >> >> >> --- > >> >> >> >> config.h.in | 3 +++ > >> >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > >> >> >> >> configure.ac | 21 +++++++++++++++ > >> >> >> >> include/libc-symbols.h | 14 +++++++--- > >> >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ > >> >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > >> >> >> >> libio/tst-cleanup.exp | 1 + > >> >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) > >> >> >> >> create mode 100644 libio/tst-cleanup.c > >> >> >> >> create mode 100644 libio/tst-cleanup.exp > >> >> >> >> > >> >> >> >> diff --git a/config.h.in b/config.h.in > >> >> >> >> index ca1547ae67..96a08c7757 100644 > >> >> >> >> --- a/config.h.in > >> >> >> >> +++ b/config.h.in > >> >> >> >> @@ -187,6 +187,9 @@ > >> >> >> >> /* Define if gcc supports attribute ifunc. */ > >> >> >> >> #undef HAVE_GCC_IFUNC > >> >> >> >> > >> >> >> >> +/* Define if CC supports attribute retain. */ > >> >> >> >> +#undef HAVE_GNU_RETAIN > >> >> >> >> + > >> >> >> >> /* Define if the linker defines __ehdr_start. */ > >> >> >> >> #undef HAVE_EHDR_START > >> >> >> >> > >> >> >> >> diff --git a/configure b/configure > >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> >> >> --- a/configure > >> >> >> >> +++ b/configure > >> >> >> >> @@ -4105,6 +4105,31 @@ fi > >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> >> >> > >> >> >> >> > >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> >> >> + $as_echo_n "(cached) " >&6 > >> >> >> >> +else > >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> +EOF > >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> >> >> + 2>&5 ; then > >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> +fi > >> >> >> >> +rm -f conftest* > >> >> >> >> +fi > >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> >> >> + > >> >> >> >> +fi > >> >> >> >> +config_vars="$config_vars > >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> >> >> + > >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> >> >> @@ -5871,6 +5896,40 @@ fi > >> >> >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> >> >> > >> >> >> >> > >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> >> >> +libc_linker_feature=no > >> >> >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> >> >> + if test -n "$libc_linker_check"; then > >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> +int _start (void) { return 42; } > >> >> >> >> +EOF > >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> >> >> + 1>&5' > >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> >> >> + (eval $ac_try) 2>&5 > >> >> >> >> + ac_status=$? > >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> >> >> + test $ac_status = 0; }; } > >> >> >> >> + then > >> >> >> >> + libc_linker_feature=yes > >> >> >> >> + fi > >> >> >> >> + rm -f conftest* > >> >> >> >> + fi > >> >> >> >> +fi > >> >> >> >> +if test $libc_linker_feature = yes; then > >> >> >> >> + libc_cv_z_start_stop_gc=yes > >> >> >> >> +else > >> >> >> >> + libc_cv_z_start_stop_gc=no > >> >> >> >> +fi > >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> >> >> +config_vars="$config_vars > >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> >> >> + > >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> >> >> libc_linker_feature=no > >> >> >> >> diff --git a/configure.ac b/configure.ac > >> >> >> >> index fce967f2c2..cc47e56e82 100644 > >> >> >> >> --- a/configure.ac > >> >> >> >> +++ b/configure.ac > >> >> >> >> @@ -707,6 +707,23 @@ fi > >> >> >> >> rm -f conftest*]) > >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> >> >> > >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> >> >> + libc_cv_gnu_retain, [dnl > >> >> >> >> +cat > conftest.c <<EOF > >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> +EOF > >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> +fi > >> >> >> >> +rm -f conftest*]) > >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> >> >> +fi > >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> >> >> + > >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> >> >> AC_SUBST(libc_cv_z_execstack) > >> >> >> >> > >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> >> >> + > >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> >> >> [-Wl,--no-dynamic-linker], > >> >> >> >> [libc_cv_no_dynamic_linker=yes], > >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> >> >> index 546fc26a7b..127ea656c2 100644 > >> >> >> >> --- a/include/libc-symbols.h > >> >> >> >> +++ b/include/libc-symbols.h > >> >> >> >> @@ -352,6 +352,12 @@ for linking") > >> >> >> >> > >> >> >> >> */ > >> >> >> >> > >> >> >> >> +#ifdef HAVE_GNU_RETAIN > >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> >> >> +#else > >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> >> >> +#endif > >> >> >> >> + > >> >> >> >> /* Symbol set support macros. */ > >> >> >> >> > >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> >> >> @@ -367,12 +373,12 @@ for linking") > >> >> >> >> /* When building a shared library, make the set section writable, > >> >> >> >> because it will need to be relocated at run time anyway. */ > >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> #else > >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> #endif > >> >> >> >> > >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> >> index 12ce41038f..c9c232ebc2 100644 > >> >> >> >> --- a/libio/Makefile > >> >> >> >> +++ b/libio/Makefile > >> >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> >> endif > >> >> >> >> + > >> >> >> >> +tests += tst-cleanup-default > >> >> >> >> +tests-static += tst-cleanup-default > >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >> >> >> > > >> >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > >> >> >> > >> >> >> Added. > >> >> >> > >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> >> + > >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >> >> >> > > >> >> >> >Same here. > >> >> >> > >> >> >> Added. > >> >> >> > >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> +endif > >> >> >> >> endif > >> >> >> >> > >> >> >> >> include ../Rules > >> >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> >> endif > >> >> >> >> > >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> + > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> + > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> > >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> >> $(common-objpfx)libio/; \ > >> >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > >> >> >> >> new file mode 100644 > >> >> >> >> index 0000000000..7f0a34a91e > >> >> >> >> --- /dev/null > >> >> >> >> +++ b/libio/tst-cleanup.c > >> >> >> >> @@ -0,0 +1,33 @@ > >> >> >> > > >> >> >> >Please add a comment saying that test --gc-sections. > >> >> >> > >> >> >> OK, added. > >> >> >> > >> >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. > >> >> >> >> + This file is part of the GNU C Library. > >> >> >> >> + > >> >> >> >> + The GNU C Library is free software; you can redistribute it and/or > >> >> >> >> + modify it under the terms of the GNU Lesser General Public > >> >> >> >> + License as published by the Free Software Foundation; either > >> >> >> >> + version 2.1 of the License, or (at your option) any later version. > >> >> >> >> + > >> >> >> >> + The GNU C Library is distributed in the hope that it will be useful, > >> >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of > >> >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > >> >> >> >> + Lesser General Public License for more details. > >> >> >> >> + > >> >> >> >> + You should have received a copy of the GNU Lesser General Public > >> >> >> >> + License along with the GNU C Library; if not, see > >> >> >> >> + <https://www.gnu.org/licenses/>. */ > >> >> >> >> + > >> >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ > >> >> >> >> + > >> >> >> >> +#include <stdio.h> > >> >> >> >> +#include <stdlib.h> > >> >> >> >> + > >> >> >> >> +void > >> >> >> >> +hook (void) > >> >> >> >> +{ > >> >> >> >> + puts ("hello"); > >> >> >> >> +} > >> >> >> >> + > >> >> >> >> +int > >> >> >> >> +main (void) > >> >> >> >> +{ > >> >> >> >> + atexit (hook); > >> >> >> >> +} > >> >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > >> >> >> >> new file mode 100644 > >> >> >> >> index 0000000000..ce01362503 > >> >> >> >> --- /dev/null > >> >> >> >> +++ b/libio/tst-cleanup.exp > >> >> >> >> @@ -0,0 +1 @@ > >> >> >> >> +hello > >> >> >> >> -- > >> >> >> >> 2.31.0.291.g576ba9dcdaf-goog > >> >> >> >> > >> >> >> > > >> >> >> > >> >> >> diff --git a/config.h.in b/config.h.in > >> >> >> index ca1547ae67..96a08c7757 100644 > >> >> >> --- a/config.h.in > >> >> >> +++ b/config.h.in > >> >> >> @@ -187,6 +187,9 @@ > >> >> >> /* Define if gcc supports attribute ifunc. */ > >> >> >> #undef HAVE_GCC_IFUNC > >> >> >> > >> >> >> +/* Define if CC supports attribute retain. */ > >> >> >> +#undef HAVE_GNU_RETAIN > >> >> >> + > >> >> >> /* Define if the linker defines __ehdr_start. */ > >> >> >> #undef HAVE_EHDR_START > >> >> >> > >> >> >> diff --git a/configure b/configure > >> >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> >> --- a/configure > >> >> >> +++ b/configure > >> >> >> @@ -4105,6 +4105,31 @@ fi > >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> >> > >> >> >> > >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> >> + $as_echo_n "(cached) " >&6 > >> >> >> +else > >> >> >> + cat > conftest.c <<EOF > >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> +EOF > >> >> >> +libc_cv_gnu_retain=no > >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> >> + 2>&5 ; then > >> >> >> + libc_cv_gnu_retain=yes > >> >> >> +fi > >> >> >> +rm -f conftest* > >> >> >> +fi > >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> >> + > >> >> >> +fi > >> >> >> +config_vars="$config_vars > >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> >> + > >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> >> @@ -5871,6 +5896,40 @@ fi > >> >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> >> > >> >> >> > >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> >> +libc_linker_feature=no > >> >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> >> + if test -n "$libc_linker_check"; then > >> >> >> + cat > conftest.c <<EOF > >> >> >> +int _start (void) { return 42; } > >> >> >> +EOF > >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> >> + 1>&5' > >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> >> + (eval $ac_try) 2>&5 > >> >> >> + ac_status=$? > >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> >> + test $ac_status = 0; }; } > >> >> >> + then > >> >> >> + libc_linker_feature=yes > >> >> >> + fi > >> >> >> + rm -f conftest* > >> >> >> + fi > >> >> >> +fi > >> >> >> +if test $libc_linker_feature = yes; then > >> >> >> + libc_cv_z_start_stop_gc=yes > >> >> >> +else > >> >> >> + libc_cv_z_start_stop_gc=no > >> >> >> +fi > >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> >> +config_vars="$config_vars > >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> >> + > >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> >> libc_linker_feature=no > >> >> >> diff --git a/configure.ac b/configure.ac > >> >> >> index fce967f2c2..cc47e56e82 100644 > >> >> >> --- a/configure.ac > >> >> >> +++ b/configure.ac > >> >> >> @@ -707,6 +707,23 @@ fi > >> >> >> rm -f conftest*]) > >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> >> > >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> >> + libc_cv_gnu_retain, [dnl > >> >> >> +cat > conftest.c <<EOF > >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> +EOF > >> >> >> +libc_cv_gnu_retain=no > >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> >> + libc_cv_gnu_retain=yes > >> >> >> +fi > >> >> >> +rm -f conftest*]) > >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> >> +fi > >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> >> + > >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> >> AC_SUBST(libc_cv_z_execstack) > >> >> >> > >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> >> + > >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> >> [-Wl,--no-dynamic-linker], > >> >> >> [libc_cv_no_dynamic_linker=yes], > >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> >> index 546fc26a7b..127ea656c2 100644 > >> >> >> --- a/include/libc-symbols.h > >> >> >> +++ b/include/libc-symbols.h > >> >> >> @@ -352,6 +352,12 @@ for linking") > >> >> >> > >> >> >> */ > >> >> >> > >> >> >> +#ifdef HAVE_GNU_RETAIN > >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> >> +#else > >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> >> +#endif > >> >> >> + > >> >> >> /* Symbol set support macros. */ > >> >> >> > >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> >> @@ -367,12 +373,12 @@ for linking") > >> >> >> /* When building a shared library, make the set section writable, > >> >> >> because it will need to be relocated at run time anyway. */ > >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> #else > >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> #endif > >> >> >> > >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> index 12ce41038f..ad0d53bb49 100644 > >> >> >> --- a/libio/Makefile > >> >> >> +++ b/libio/Makefile > >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> endif > >> >> >> + > >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static > >> >> >> +tests-static += tst-cleanup-default-static > >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> >> >> + > >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> +endif > >> >> >> endif > >> >> >> > >> >> >> include ../Rules > >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> endif > >> >> >> > >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> >> + $(compile.c) -o $@ > >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c > >> >> >> + $(compile.c) -o $@ > >> >> >> + > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> + $(compile.c) -o $@ > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > >> >> >> + $(compile.c) -o $@ > >> >> > > >> >> >Please add a separate .c file for each test to get the correct dependency. > >> >> > >> >> Changed this block to: > >> >> > >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> endif > >> >> > >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c > >> >> + cp $< $@ > >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c > >> >> + cp $< $@ > >> >> + > >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> + $(compile.c) -o $@ > >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c > >> >> + cp $< $@ > >> >> + > >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c > >> >> + cp $< $@ > >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out > >> >> + cmp $^ > $@; \ > >> >> + $(evaluate-test) > >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c > >> >> + cp $< $@ > >> >> + > >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> $(common-objpfx)libio/; \ > >> >> > >> > > >> >"make clean" doesn't remove the generated files. The standard way in glibc > >> >is to add a *-static.c source. > >> > >> I'll use .INTERMEDIATE and $(eval $(call ..)) > >> > >> diff --git a/libio/Makefile b/libio/Makefile > >> index 12ce41038f..a9b44f04df 100644 > >> --- a/libio/Makefile > >> +++ b/libio/Makefile > >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> $(objpfx)tst-bz24228-mem.out > >> endif > >> + > >> +tests += tst-cleanup-default tst-cleanup-default-static > >> +tests-static += tst-cleanup-default-static > >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> + > >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> +endif > >> endif > >> > >> include ../Rules > >> @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> endif > >> > >> +define gen-tst-cleanup > >> +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out > >> + cmp $$^ > $$@; $$(evaluate-test) > >> +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c > >> + cp $$< $$@ > >> +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c > >> +endef > >> + > >> +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ > >> + $(eval $(call gen-tst-cleanup,$(t)))) > >> + > >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> $(common-objpfx)libio/; \ > > > >There are 2 issues with static tests: > > > >1. A separate static source is needed. > > .INTERMEDIATE perfectly solves the lingering copied source issue. > I don't see lingering libio/tst-cleanup-*.c I was referring to elf/tst-array1-static.c elf/tst-array5-static.c elf/tst-dl-iter-static.c elf/tst-dst-static.c elf/tst-leaks1-static.c elf/tst-libc_dlvsym-static.c elf/tst-linkall-static.c elf/tst-ptrguard1-static.c elf/tst-single_threaded-pthread-static.c elf/tst-single_threaded-static.c elf/tst-stackguard1-static.c elf/tst-tls1-static.c elf/tst-tls2-static.c elf/tst-tls9-static.c elf/tst-tlsalign-extern-static.c elf/tst-tlsalign-static.c gmon/tst-gmon-static.c gmon/tst-profile-static.c localedata/bug-setlocale1-static.c localedata/tst-langinfo-newlocale-static.c localedata/tst-langinfo-setlocale-static.c localedata/tst-langinfo-static.c malloc/tst-malloc-usable-static.c math/test-fpucw-ieee-static.c math/test-fpucw-static.c math/test-signgam-uchar-init-static.c math/test-signgam-uchar-static.c math/test-signgam-uint-init-static.c math/test-signgam-uint-static.c math/test-signgam-ullong-init-static.c math/test-signgam-ullong-static.c nptl/tst-mutex8-static.c nptl/tst-mutexpi8-static.c nptl/tst-sem11-static.c nptl/tst-sem12-static.c nptl/tst-setuid1-static.c nptl/tst-stackguard1-static.c nss/tst-nss-static.c posix/tst-exec-static.c posix/tst-spawn-static.c setjmp/tst-setjmp-static.c > >2. We need to add the static test to both tests and tests-static. > > tests-static suffices. I have checked some tests-static usage in other > directories. There are tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ tst-sigsetjmp tst-setjmp-static tests-static := tst-setjmp-static They should be replaced by something like tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ tst-sigsetjmp tests-static-add := tst-setjmp-static > I have additionally checked that: > > * touch libc.a => next invocation `make -r -C ~/Dev/glibc/libio objdir=$PWD check -j 20` will rebuild the static tests > * touch libc.so => next invocation `make -r -C ~/Dev/glibc/libio objdir=$PWD check -j 20` will rebuild the dynamic tests > * rm libio/tst-cleanup-default-cmp.out => next invocation `make -r -C ~/Dev/glibc/libio objdir=$PWD check -j 20` will rerun the single test > > >If you want to add a separate static source, you can submit a separate patch > >to address these 2 issues together. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-05 20:35 ` H.J. Lu @ 2021-04-05 21:03 ` Fangrui Song 2021-04-05 21:58 ` H.J. Lu 0 siblings, 1 reply; 40+ messages in thread From: Fangrui Song @ 2021-04-05 21:03 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-04-05, H.J. Lu wrote: >On Mon, Apr 5, 2021 at 11:17 AM Fangrui Song <maskray@google.com> wrote: >> >> On 2021-04-04, H.J. Lu wrote: >> >On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> On 2021-04-03, H.J. Lu wrote: >> >> >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> >> >> >> On 2021-04-02, H.J. Lu wrote: >> >> >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> >> >> On 2021-04-01, H.J. Lu wrote: >> >> >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined >> >> >> >> >> variables will be retained by the linker. >> >> >> >> >> >> >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> >> >> >> >> will not be optimized out; 'retain' prevents section garbage collection >> >> >> >> >> if the linker support SHF_GNU_RETAIN. >> >> >> >> >> >> >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> >> >> >> >> identifier name sections to be GCed even if there are live >> >> >> >> >> __start_/__stop_ references. >> >> >> >> >> >> >> >> >> >> Without the change, there are some static linking problems, e.g. >> >> >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> >> >> >> >> stdout is not flushed on exit. >> >> >> >> >> >> >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> >> >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> >> >> >> >> --- >> >> >> >> >> Changes in v1 -> v2: >> >> >> >> >> * Define attribute_used_retain_section >> >> >> >> >> Changes in v2 -> v3: >> >> >> >> >> * Use attribute_used_retain instead attribute_used_retain_section >> >> >> >> >> Changes in v3 -> v4: >> >> >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests >> >> >> >> >> Changes in v4 -> v5: >> >> >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported >> >> >> >> >> * Rename *gcc_retain* to *gnu_retain* >> >> >> >> >> --- >> >> >> >> >> config.h.in | 3 +++ >> >> >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ >> >> >> >> >> configure.ac | 21 +++++++++++++++ >> >> >> >> >> include/libc-symbols.h | 14 +++++++--- >> >> >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ >> >> >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ >> >> >> >> >> libio/tst-cleanup.exp | 1 + >> >> >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) >> >> >> >> >> create mode 100644 libio/tst-cleanup.c >> >> >> >> >> create mode 100644 libio/tst-cleanup.exp >> >> >> >> >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> >> >> >> index ca1547ae67..96a08c7757 100644 >> >> >> >> >> --- a/config.h.in >> >> >> >> >> +++ b/config.h.in >> >> >> >> >> @@ -187,6 +187,9 @@ >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ >> >> >> >> >> #undef HAVE_GCC_IFUNC >> >> >> >> >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> >> >> >> +#undef HAVE_GNU_RETAIN >> >> >> >> >> + >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ >> >> >> >> >> #undef HAVE_EHDR_START >> >> >> >> >> >> >> >> >> >> diff --git a/configure b/configure >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> >> >> >> --- a/configure >> >> >> >> >> +++ b/configure >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> >> >> >> + $as_echo_n "(cached) " >&6 >> >> >> >> >> +else >> >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> >> +EOF >> >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> >> >> >> + 2>&5 ; then >> >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> >> +fi >> >> >> >> >> +rm -f conftest* >> >> >> >> >> +fi >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> >> >> >> + >> >> >> >> >> +fi >> >> >> >> >> +config_vars="$config_vars >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> >> >> >> + >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> >> >> >> +libc_linker_feature=no >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> >> >> >> + if test -n "$libc_linker_check"; then >> >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> >> +int _start (void) { return 42; } >> >> >> >> >> +EOF >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c >> >> >> >> >> + 1>&5' >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> >> >> >> + (eval $ac_try) 2>&5 >> >> >> >> >> + ac_status=$? >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> >> >> >> + test $ac_status = 0; }; } >> >> >> >> >> + then >> >> >> >> >> + libc_linker_feature=yes >> >> >> >> >> + fi >> >> >> >> >> + rm -f conftest* >> >> >> >> >> + fi >> >> >> >> >> +fi >> >> >> >> >> +if test $libc_linker_feature = yes; then >> >> >> >> >> + libc_cv_z_start_stop_gc=yes >> >> >> >> >> +else >> >> >> >> >> + libc_cv_z_start_stop_gc=no >> >> >> >> >> +fi >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> +config_vars="$config_vars >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> >> >> >> + >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> >> >> >> libc_linker_feature=no >> >> >> >> >> diff --git a/configure.ac b/configure.ac >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 >> >> >> >> >> --- a/configure.ac >> >> >> >> >> +++ b/configure.ac >> >> >> >> >> @@ -707,6 +707,23 @@ fi >> >> >> >> >> rm -f conftest*]) >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> >> >> >> + libc_cv_gnu_retain, [dnl >> >> >> >> >> +cat > conftest.c <<EOF >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> >> +EOF >> >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> >> +fi >> >> >> >> >> +rm -f conftest*]) >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> >> >> >> +fi >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> >> >> >> + >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> >> >> >> + >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> >> >> >> [-Wl,--no-dynamic-linker], >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 >> >> >> >> >> --- a/include/libc-symbols.h >> >> >> >> >> +++ b/include/libc-symbols.h >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> >> >> >> >> >> >> */ >> >> >> >> >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> >> >> >> +#else >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> >> >> >> +#endif >> >> >> >> >> + >> >> >> >> >> /* Symbol set support macros. */ >> >> >> >> >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") >> >> >> >> >> /* When building a shared library, make the set section writable, >> >> >> >> >> because it will need to be relocated at run time anyway. */ >> >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> >> #else >> >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> >> #endif >> >> >> >> >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> >> >> >> index 12ce41038f..c9c232ebc2 100644 >> >> >> >> >> --- a/libio/Makefile >> >> >> >> >> +++ b/libio/Makefile >> >> >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> >> >> >> $(objpfx)tst-bz24228-mem.out >> >> >> >> >> endif >> >> >> >> >> + >> >> >> >> >> +tests += tst-cleanup-default >> >> >> >> >> +tests-static += tst-cleanup-default >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out >> >> >> >> > >> >> >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. >> >> >> >> >> >> >> >> Added. >> >> >> >> >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> >> >> >> + >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out >> >> >> >> > >> >> >> >> >Same here. >> >> >> >> >> >> >> >> Added. >> >> >> >> >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> >> >> +endif >> >> >> >> >> endif >> >> >> >> >> >> >> >> >> >> include ../Rules >> >> >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> >> >> endif >> >> >> >> >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> + >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> + >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> >> >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> >> >> >> $(common-objpfx)libio/; \ >> >> >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> >> >> >> >> new file mode 100644 >> >> >> >> >> index 0000000000..7f0a34a91e >> >> >> >> >> --- /dev/null >> >> >> >> >> +++ b/libio/tst-cleanup.c >> >> >> >> >> @@ -0,0 +1,33 @@ >> >> >> >> > >> >> >> >> >Please add a comment saying that test --gc-sections. >> >> >> >> >> >> >> >> OK, added. >> >> >> >> >> >> >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> >> >> >> >> + This file is part of the GNU C Library. >> >> >> >> >> + >> >> >> >> >> + The GNU C Library is free software; you can redistribute it and/or >> >> >> >> >> + modify it under the terms of the GNU Lesser General Public >> >> >> >> >> + License as published by the Free Software Foundation; either >> >> >> >> >> + version 2.1 of the License, or (at your option) any later version. >> >> >> >> >> + >> >> >> >> >> + The GNU C Library is distributed in the hope that it will be useful, >> >> >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> >> >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> >> >> >> >> + Lesser General Public License for more details. >> >> >> >> >> + >> >> >> >> >> + You should have received a copy of the GNU Lesser General Public >> >> >> >> >> + License along with the GNU C Library; if not, see >> >> >> >> >> + <https://www.gnu.org/licenses/>. */ >> >> >> >> >> + >> >> >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> >> >> >> >> + >> >> >> >> >> +#include <stdio.h> >> >> >> >> >> +#include <stdlib.h> >> >> >> >> >> + >> >> >> >> >> +void >> >> >> >> >> +hook (void) >> >> >> >> >> +{ >> >> >> >> >> + puts ("hello"); >> >> >> >> >> +} >> >> >> >> >> + >> >> >> >> >> +int >> >> >> >> >> +main (void) >> >> >> >> >> +{ >> >> >> >> >> + atexit (hook); >> >> >> >> >> +} >> >> >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> >> >> >> >> new file mode 100644 >> >> >> >> >> index 0000000000..ce01362503 >> >> >> >> >> --- /dev/null >> >> >> >> >> +++ b/libio/tst-cleanup.exp >> >> >> >> >> @@ -0,0 +1 @@ >> >> >> >> >> +hello >> >> >> >> >> -- >> >> >> >> >> 2.31.0.291.g576ba9dcdaf-goog >> >> >> >> >> >> >> >> >> > >> >> >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> >> >> index ca1547ae67..96a08c7757 100644 >> >> >> >> --- a/config.h.in >> >> >> >> +++ b/config.h.in >> >> >> >> @@ -187,6 +187,9 @@ >> >> >> >> /* Define if gcc supports attribute ifunc. */ >> >> >> >> #undef HAVE_GCC_IFUNC >> >> >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> >> >> +#undef HAVE_GNU_RETAIN >> >> >> >> + >> >> >> >> /* Define if the linker defines __ehdr_start. */ >> >> >> >> #undef HAVE_EHDR_START >> >> >> >> >> >> >> >> diff --git a/configure b/configure >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> >> >> --- a/configure >> >> >> >> +++ b/configure >> >> >> >> @@ -4105,6 +4105,31 @@ fi >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> >> >> + $as_echo_n "(cached) " >&6 >> >> >> >> +else >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> +EOF >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> >> >> + 2>&5 ; then >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> +fi >> >> >> >> +rm -f conftest* >> >> >> >> +fi >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> >> >> + >> >> >> >> +fi >> >> >> >> +config_vars="$config_vars >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> >> >> + >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> >> >> @@ -5871,6 +5896,40 @@ fi >> >> >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> >> >> +libc_linker_feature=no >> >> >> >> +if test x"$gnu_ld" = x"yes"; then >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> >> >> + if test -n "$libc_linker_check"; then >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> +int _start (void) { return 42; } >> >> >> >> +EOF >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> >> >> + -fPIC -shared -o conftest.so conftest.c >> >> >> >> + 1>&5' >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> >> >> + (eval $ac_try) 2>&5 >> >> >> >> + ac_status=$? >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> >> >> + test $ac_status = 0; }; } >> >> >> >> + then >> >> >> >> + libc_linker_feature=yes >> >> >> >> + fi >> >> >> >> + rm -f conftest* >> >> >> >> + fi >> >> >> >> +fi >> >> >> >> +if test $libc_linker_feature = yes; then >> >> >> >> + libc_cv_z_start_stop_gc=yes >> >> >> >> +else >> >> >> >> + libc_cv_z_start_stop_gc=no >> >> >> >> +fi >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> >> >> +config_vars="$config_vars >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> >> >> + >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> >> >> libc_linker_feature=no >> >> >> >> diff --git a/configure.ac b/configure.ac >> >> >> >> index fce967f2c2..cc47e56e82 100644 >> >> >> >> --- a/configure.ac >> >> >> >> +++ b/configure.ac >> >> >> >> @@ -707,6 +707,23 @@ fi >> >> >> >> rm -f conftest*]) >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> >> >> + libc_cv_gnu_retain, [dnl >> >> >> >> +cat > conftest.c <<EOF >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> +EOF >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> +fi >> >> >> >> +rm -f conftest*]) >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> >> >> +fi >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> >> >> + >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> >> >> + >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> >> >> [-Wl,--no-dynamic-linker], >> >> >> >> [libc_cv_no_dynamic_linker=yes], >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> >> >> index 546fc26a7b..127ea656c2 100644 >> >> >> >> --- a/include/libc-symbols.h >> >> >> >> +++ b/include/libc-symbols.h >> >> >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> >> >> >> >> */ >> >> >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> >> >> +#else >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> >> >> +#endif >> >> >> >> + >> >> >> >> /* Symbol set support macros. */ >> >> >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> >> >> @@ -367,12 +373,12 @@ for linking") >> >> >> >> /* When building a shared library, make the set section writable, >> >> >> >> because it will need to be relocated at run time anyway. */ >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> #else >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> #endif >> >> >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> >> >> index 12ce41038f..ad0d53bb49 100644 >> >> >> >> --- a/libio/Makefile >> >> >> >> +++ b/libio/Makefile >> >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> >> >> $(objpfx)tst-bz24228-mem.out >> >> >> >> endif >> >> >> >> + >> >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static >> >> >> >> +tests-static += tst-cleanup-default-static >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections >> >> >> >> + >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ >> >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static >> >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> >> +endif >> >> >> >> endif >> >> >> >> >> >> >> >> include ../Rules >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> >> endif >> >> >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> >> >> + $(compile.c) -o $@ >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c >> >> >> >> + $(compile.c) -o $@ >> >> >> >> + >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> >> >> + $(compile.c) -o $@ >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c >> >> >> >> + $(compile.c) -o $@ >> >> >> > >> >> >> >Please add a separate .c file for each test to get the correct dependency. >> >> >> >> >> >> Changed this block to: >> >> >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> endif >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c >> >> >> + cp $< $@ >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c >> >> >> + cp $< $@ >> >> >> + >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> >> + $(compile.c) -o $@ >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c >> >> >> + cp $< $@ >> >> >> + >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c >> >> >> + cp $< $@ >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out >> >> >> + cmp $^ > $@; \ >> >> >> + $(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c >> >> >> + cp $< $@ >> >> >> + >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> >> $(common-objpfx)libio/; \ >> >> >> >> >> > >> >> >"make clean" doesn't remove the generated files. The standard way in glibc >> >> >is to add a *-static.c source. >> >> >> >> I'll use .INTERMEDIATE and $(eval $(call ..)) >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> index 12ce41038f..a9b44f04df 100644 >> >> --- a/libio/Makefile >> >> +++ b/libio/Makefile >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> $(objpfx)tst-bz24228-mem.out >> >> endif >> >> + >> >> +tests += tst-cleanup-default tst-cleanup-default-static >> >> +tests-static += tst-cleanup-default-static >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections >> >> + >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc >> >> +endif >> >> endif >> >> >> >> include ../Rules >> >> @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> endif >> >> >> >> +define gen-tst-cleanup >> >> +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out >> >> + cmp $$^ > $$@; $$(evaluate-test) >> >> +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c >> >> + cp $$< $$@ >> >> +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c >> >> +endef >> >> + >> >> +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ >> >> + $(eval $(call gen-tst-cleanup,$(t)))) >> >> + >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> $(common-objpfx)libio/; \ >> > >> >There are 2 issues with static tests: >> > >> >1. A separate static source is needed. >> >> .INTERMEDIATE perfectly solves the lingering copied source issue. >> I don't see lingering libio/tst-cleanup-*.c > >I was referring to > >elf/tst-array1-static.c >elf/tst-array5-static.c >elf/tst-dl-iter-static.c >elf/tst-dst-static.c >elf/tst-leaks1-static.c >elf/tst-libc_dlvsym-static.c >elf/tst-linkall-static.c >elf/tst-ptrguard1-static.c >elf/tst-single_threaded-pthread-static.c >elf/tst-single_threaded-static.c >elf/tst-stackguard1-static.c >elf/tst-tls1-static.c >elf/tst-tls2-static.c >elf/tst-tls9-static.c >elf/tst-tlsalign-extern-static.c >elf/tst-tlsalign-static.c >gmon/tst-gmon-static.c >gmon/tst-profile-static.c >localedata/bug-setlocale1-static.c >localedata/tst-langinfo-newlocale-static.c >localedata/tst-langinfo-setlocale-static.c >localedata/tst-langinfo-static.c >malloc/tst-malloc-usable-static.c >math/test-fpucw-ieee-static.c >math/test-fpucw-static.c >math/test-signgam-uchar-init-static.c >math/test-signgam-uchar-static.c >math/test-signgam-uint-init-static.c >math/test-signgam-uint-static.c >math/test-signgam-ullong-init-static.c >math/test-signgam-ullong-static.c >nptl/tst-mutex8-static.c >nptl/tst-mutexpi8-static.c >nptl/tst-sem11-static.c >nptl/tst-sem12-static.c >nptl/tst-setuid1-static.c >nptl/tst-stackguard1-static.c >nss/tst-nss-static.c >posix/tst-exec-static.c >posix/tst-spawn-static.c >setjmp/tst-setjmp-static.c > >> >2. We need to add the static test to both tests and tests-static. >> >> tests-static suffices. I have checked some tests-static usage in other >> directories. > >There are > >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > tst-sigsetjmp tst-setjmp-static >tests-static := tst-setjmp-static > >They should be replaced by something like > >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > tst-sigsetjmp >tests-static-add := tst-setjmp-static Re-checking, the tst-cleanup* targets are in tests-special so `make tests` will build them. If a tests-static target is not in tests-internal/tests-special, looks like it needs to be in tests. As is, I think my usage is correct. >> I have additionally checked that: >> >> * touch libc.a => next invocation `make -r -C ~/Dev/glibc/libio objdir=$PWD check -j 20` will rebuild the static tests >> * touch libc.so => next invocation `make -r -C ~/Dev/glibc/libio objdir=$PWD check -j 20` will rebuild the dynamic tests >> * rm libio/tst-cleanup-default-cmp.out => next invocation `make -r -C ~/Dev/glibc/libio objdir=$PWD check -j 20` will rerun the single test >> >> >If you want to add a separate static source, you can submit a separate patch >> >to address these 2 issues together. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-05 21:03 ` Fangrui Song @ 2021-04-05 21:58 ` H.J. Lu 2021-04-06 21:46 ` Fangrui Song 0 siblings, 1 reply; 40+ messages in thread From: H.J. Lu @ 2021-04-05 21:58 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Mon, Apr 5, 2021 at 2:03 PM Fangrui Song <maskray@google.com> wrote: > > On 2021-04-05, H.J. Lu wrote: > >On Mon, Apr 5, 2021 at 11:17 AM Fangrui Song <maskray@google.com> wrote: > >> > >> On 2021-04-04, H.J. Lu wrote: > >> >On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song <maskray@google.com> wrote: > >> >> > >> >> On 2021-04-03, H.J. Lu wrote: > >> >> >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: > >> >> >> > >> >> >> > >> >> >> On 2021-04-02, H.J. Lu wrote: > >> >> >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> >> > >> >> >> >> On 2021-04-01, H.J. Lu wrote: > >> >> >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> >> >> > >> >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined > >> >> >> >> >> variables will be retained by the linker. > >> >> >> >> >> > >> >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> >> >> >> >> will not be optimized out; 'retain' prevents section garbage collection > >> >> >> >> >> if the linker support SHF_GNU_RETAIN. > >> >> >> >> >> > >> >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> >> >> >> >> identifier name sections to be GCed even if there are live > >> >> >> >> >> __start_/__stop_ references. > >> >> >> >> >> > >> >> >> >> >> Without the change, there are some static linking problems, e.g. > >> >> >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> >> >> >> >> stdout is not flushed on exit. > >> >> >> >> >> > >> >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> >> >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> >> >> >> >> --- > >> >> >> >> >> Changes in v1 -> v2: > >> >> >> >> >> * Define attribute_used_retain_section > >> >> >> >> >> Changes in v2 -> v3: > >> >> >> >> >> * Use attribute_used_retain instead attribute_used_retain_section > >> >> >> >> >> Changes in v3 -> v4: > >> >> >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> >> >> >> >> Changes in v4 -> v5: > >> >> >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > >> >> >> >> >> * Rename *gcc_retain* to *gnu_retain* > >> >> >> >> >> --- > >> >> >> >> >> config.h.in | 3 +++ > >> >> >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > >> >> >> >> >> configure.ac | 21 +++++++++++++++ > >> >> >> >> >> include/libc-symbols.h | 14 +++++++--- > >> >> >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ > >> >> >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > >> >> >> >> >> libio/tst-cleanup.exp | 1 + > >> >> >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) > >> >> >> >> >> create mode 100644 libio/tst-cleanup.c > >> >> >> >> >> create mode 100644 libio/tst-cleanup.exp > >> >> >> >> >> > >> >> >> >> >> diff --git a/config.h.in b/config.h.in > >> >> >> >> >> index ca1547ae67..96a08c7757 100644 > >> >> >> >> >> --- a/config.h.in > >> >> >> >> >> +++ b/config.h.in > >> >> >> >> >> @@ -187,6 +187,9 @@ > >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ > >> >> >> >> >> #undef HAVE_GCC_IFUNC > >> >> >> >> >> > >> >> >> >> >> +/* Define if CC supports attribute retain. */ > >> >> >> >> >> +#undef HAVE_GNU_RETAIN > >> >> >> >> >> + > >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ > >> >> >> >> >> #undef HAVE_EHDR_START > >> >> >> >> >> > >> >> >> >> >> diff --git a/configure b/configure > >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> >> >> >> --- a/configure > >> >> >> >> >> +++ b/configure > >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi > >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> >> >> >> > >> >> >> >> >> > >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> >> >> >> + $as_echo_n "(cached) " >&6 > >> >> >> >> >> +else > >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> +EOF > >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> >> >> >> + 2>&5 ; then > >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> +fi > >> >> >> >> >> +rm -f conftest* > >> >> >> >> >> +fi > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> >> >> >> + > >> >> >> >> >> +fi > >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> >> >> >> + > >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi > >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> > >> >> >> >> >> > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> >> >> >> +libc_linker_feature=no > >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> >> >> >> + if test -n "$libc_linker_check"; then > >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> +int _start (void) { return 42; } > >> >> >> >> >> +EOF > >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> >> >> >> + 1>&5' > >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> >> >> >> + (eval $ac_try) 2>&5 > >> >> >> >> >> + ac_status=$? > >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> >> >> >> + test $ac_status = 0; }; } > >> >> >> >> >> + then > >> >> >> >> >> + libc_linker_feature=yes > >> >> >> >> >> + fi > >> >> >> >> >> + rm -f conftest* > >> >> >> >> >> + fi > >> >> >> >> >> +fi > >> >> >> >> >> +if test $libc_linker_feature = yes; then > >> >> >> >> >> + libc_cv_z_start_stop_gc=yes > >> >> >> >> >> +else > >> >> >> >> >> + libc_cv_z_start_stop_gc=no > >> >> >> >> >> +fi > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> >> >> >> + > >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> >> >> >> libc_linker_feature=no > >> >> >> >> >> diff --git a/configure.ac b/configure.ac > >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 > >> >> >> >> >> --- a/configure.ac > >> >> >> >> >> +++ b/configure.ac > >> >> >> >> >> @@ -707,6 +707,23 @@ fi > >> >> >> >> >> rm -f conftest*]) > >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> >> >> >> > >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> >> >> >> + libc_cv_gnu_retain, [dnl > >> >> >> >> >> +cat > conftest.c <<EOF > >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> +EOF > >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> +fi > >> >> >> >> >> +rm -f conftest*]) > >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> >> >> >> +fi > >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> >> >> >> + > >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) > >> >> >> >> >> > >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> >> >> >> + > >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> >> >> >> [-Wl,--no-dynamic-linker], > >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], > >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 > >> >> >> >> >> --- a/include/libc-symbols.h > >> >> >> >> >> +++ b/include/libc-symbols.h > >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") > >> >> >> >> >> > >> >> >> >> >> */ > >> >> >> >> >> > >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN > >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> >> >> >> +#else > >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> >> >> >> +#endif > >> >> >> >> >> + > >> >> >> >> >> /* Symbol set support macros. */ > >> >> >> >> >> > >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") > >> >> >> >> >> /* When building a shared library, make the set section writable, > >> >> >> >> >> because it will need to be relocated at run time anyway. */ > >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> #else > >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> #endif > >> >> >> >> >> > >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> >> >> index 12ce41038f..c9c232ebc2 100644 > >> >> >> >> >> --- a/libio/Makefile > >> >> >> >> >> +++ b/libio/Makefile > >> >> >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> >> >> endif > >> >> >> >> >> + > >> >> >> >> >> +tests += tst-cleanup-default > >> >> >> >> >> +tests-static += tst-cleanup-default > >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >> >> >> >> > > >> >> >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > >> >> >> >> > >> >> >> >> Added. > >> >> >> >> > >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> >> >> + > >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >> >> >> >> > > >> >> >> >> >Same here. > >> >> >> >> > >> >> >> >> Added. > >> >> >> >> > >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> >> +endif > >> >> >> >> >> endif > >> >> >> >> >> > >> >> >> >> >> include ../Rules > >> >> >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> >> >> endif > >> >> >> >> >> > >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> + > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> + > >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> > >> >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> >> >> $(common-objpfx)libio/; \ > >> >> >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > >> >> >> >> >> new file mode 100644 > >> >> >> >> >> index 0000000000..7f0a34a91e > >> >> >> >> >> --- /dev/null > >> >> >> >> >> +++ b/libio/tst-cleanup.c > >> >> >> >> >> @@ -0,0 +1,33 @@ > >> >> >> >> > > >> >> >> >> >Please add a comment saying that test --gc-sections. > >> >> >> >> > >> >> >> >> OK, added. > >> >> >> >> > >> >> >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. > >> >> >> >> >> + This file is part of the GNU C Library. > >> >> >> >> >> + > >> >> >> >> >> + The GNU C Library is free software; you can redistribute it and/or > >> >> >> >> >> + modify it under the terms of the GNU Lesser General Public > >> >> >> >> >> + License as published by the Free Software Foundation; either > >> >> >> >> >> + version 2.1 of the License, or (at your option) any later version. > >> >> >> >> >> + > >> >> >> >> >> + The GNU C Library is distributed in the hope that it will be useful, > >> >> >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of > >> >> >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > >> >> >> >> >> + Lesser General Public License for more details. > >> >> >> >> >> + > >> >> >> >> >> + You should have received a copy of the GNU Lesser General Public > >> >> >> >> >> + License along with the GNU C Library; if not, see > >> >> >> >> >> + <https://www.gnu.org/licenses/>. */ > >> >> >> >> >> + > >> >> >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ > >> >> >> >> >> + > >> >> >> >> >> +#include <stdio.h> > >> >> >> >> >> +#include <stdlib.h> > >> >> >> >> >> + > >> >> >> >> >> +void > >> >> >> >> >> +hook (void) > >> >> >> >> >> +{ > >> >> >> >> >> + puts ("hello"); > >> >> >> >> >> +} > >> >> >> >> >> + > >> >> >> >> >> +int > >> >> >> >> >> +main (void) > >> >> >> >> >> +{ > >> >> >> >> >> + atexit (hook); > >> >> >> >> >> +} > >> >> >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > >> >> >> >> >> new file mode 100644 > >> >> >> >> >> index 0000000000..ce01362503 > >> >> >> >> >> --- /dev/null > >> >> >> >> >> +++ b/libio/tst-cleanup.exp > >> >> >> >> >> @@ -0,0 +1 @@ > >> >> >> >> >> +hello > >> >> >> >> >> -- > >> >> >> >> >> 2.31.0.291.g576ba9dcdaf-goog > >> >> >> >> >> > >> >> >> >> > > >> >> >> >> > >> >> >> >> diff --git a/config.h.in b/config.h.in > >> >> >> >> index ca1547ae67..96a08c7757 100644 > >> >> >> >> --- a/config.h.in > >> >> >> >> +++ b/config.h.in > >> >> >> >> @@ -187,6 +187,9 @@ > >> >> >> >> /* Define if gcc supports attribute ifunc. */ > >> >> >> >> #undef HAVE_GCC_IFUNC > >> >> >> >> > >> >> >> >> +/* Define if CC supports attribute retain. */ > >> >> >> >> +#undef HAVE_GNU_RETAIN > >> >> >> >> + > >> >> >> >> /* Define if the linker defines __ehdr_start. */ > >> >> >> >> #undef HAVE_EHDR_START > >> >> >> >> > >> >> >> >> diff --git a/configure b/configure > >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> >> >> --- a/configure > >> >> >> >> +++ b/configure > >> >> >> >> @@ -4105,6 +4105,31 @@ fi > >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> >> >> > >> >> >> >> > >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> >> >> + $as_echo_n "(cached) " >&6 > >> >> >> >> +else > >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> +EOF > >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> >> >> + 2>&5 ; then > >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> +fi > >> >> >> >> +rm -f conftest* > >> >> >> >> +fi > >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> >> >> + > >> >> >> >> +fi > >> >> >> >> +config_vars="$config_vars > >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> >> >> + > >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> >> >> @@ -5871,6 +5896,40 @@ fi > >> >> >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> >> >> > >> >> >> >> > >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> >> >> +libc_linker_feature=no > >> >> >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> >> >> + if test -n "$libc_linker_check"; then > >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> +int _start (void) { return 42; } > >> >> >> >> +EOF > >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> >> >> + 1>&5' > >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> >> >> + (eval $ac_try) 2>&5 > >> >> >> >> + ac_status=$? > >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> >> >> + test $ac_status = 0; }; } > >> >> >> >> + then > >> >> >> >> + libc_linker_feature=yes > >> >> >> >> + fi > >> >> >> >> + rm -f conftest* > >> >> >> >> + fi > >> >> >> >> +fi > >> >> >> >> +if test $libc_linker_feature = yes; then > >> >> >> >> + libc_cv_z_start_stop_gc=yes > >> >> >> >> +else > >> >> >> >> + libc_cv_z_start_stop_gc=no > >> >> >> >> +fi > >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> >> >> +config_vars="$config_vars > >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> >> >> + > >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> >> >> libc_linker_feature=no > >> >> >> >> diff --git a/configure.ac b/configure.ac > >> >> >> >> index fce967f2c2..cc47e56e82 100644 > >> >> >> >> --- a/configure.ac > >> >> >> >> +++ b/configure.ac > >> >> >> >> @@ -707,6 +707,23 @@ fi > >> >> >> >> rm -f conftest*]) > >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> >> >> > >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> >> >> + libc_cv_gnu_retain, [dnl > >> >> >> >> +cat > conftest.c <<EOF > >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> +EOF > >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> +fi > >> >> >> >> +rm -f conftest*]) > >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> >> >> +fi > >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> >> >> + > >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> >> >> AC_SUBST(libc_cv_z_execstack) > >> >> >> >> > >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> >> >> + > >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> >> >> [-Wl,--no-dynamic-linker], > >> >> >> >> [libc_cv_no_dynamic_linker=yes], > >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> >> >> index 546fc26a7b..127ea656c2 100644 > >> >> >> >> --- a/include/libc-symbols.h > >> >> >> >> +++ b/include/libc-symbols.h > >> >> >> >> @@ -352,6 +352,12 @@ for linking") > >> >> >> >> > >> >> >> >> */ > >> >> >> >> > >> >> >> >> +#ifdef HAVE_GNU_RETAIN > >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> >> >> +#else > >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> >> >> +#endif > >> >> >> >> + > >> >> >> >> /* Symbol set support macros. */ > >> >> >> >> > >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> >> >> @@ -367,12 +373,12 @@ for linking") > >> >> >> >> /* When building a shared library, make the set section writable, > >> >> >> >> because it will need to be relocated at run time anyway. */ > >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> #else > >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> #endif > >> >> >> >> > >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> >> index 12ce41038f..ad0d53bb49 100644 > >> >> >> >> --- a/libio/Makefile > >> >> >> >> +++ b/libio/Makefile > >> >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> >> endif > >> >> >> >> + > >> >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static > >> >> >> >> +tests-static += tst-cleanup-default-static > >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> >> >> >> + > >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> +endif > >> >> >> >> endif > >> >> >> >> > >> >> >> >> include ../Rules > >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> >> endif > >> >> >> >> > >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c > >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> + > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > >> >> >> >> + $(compile.c) -o $@ > >> >> >> > > >> >> >> >Please add a separate .c file for each test to get the correct dependency. > >> >> >> > >> >> >> Changed this block to: > >> >> >> > >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> endif > >> >> >> > >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c > >> >> >> + cp $< $@ > >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c > >> >> >> + cp $< $@ > >> >> >> + > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> + $(compile.c) -o $@ > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c > >> >> >> + cp $< $@ > >> >> >> + > >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c > >> >> >> + cp $< $@ > >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out > >> >> >> + cmp $^ > $@; \ > >> >> >> + $(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c > >> >> >> + cp $< $@ > >> >> >> + > >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> $(common-objpfx)libio/; \ > >> >> >> > >> >> > > >> >> >"make clean" doesn't remove the generated files. The standard way in glibc > >> >> >is to add a *-static.c source. > >> >> > >> >> I'll use .INTERMEDIATE and $(eval $(call ..)) > >> >> > >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> index 12ce41038f..a9b44f04df 100644 > >> >> --- a/libio/Makefile > >> >> +++ b/libio/Makefile > >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> $(objpfx)tst-bz24228-mem.out > >> >> endif > >> >> + > >> >> +tests += tst-cleanup-default tst-cleanup-default-static > >> >> +tests-static += tst-cleanup-default-static > >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> >> + > >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> +endif > >> >> endif > >> >> > >> >> include ../Rules > >> >> @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> endif > >> >> > >> >> +define gen-tst-cleanup > >> >> +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out > >> >> + cmp $$^ > $$@; $$(evaluate-test) > >> >> +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c > >> >> + cp $$< $$@ > >> >> +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c > >> >> +endef > >> >> + > >> >> +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ > >> >> + $(eval $(call gen-tst-cleanup,$(t)))) > >> >> + > >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> $(common-objpfx)libio/; \ > >> > > >> >There are 2 issues with static tests: > >> > > >> >1. A separate static source is needed. > >> > >> .INTERMEDIATE perfectly solves the lingering copied source issue. > >> I don't see lingering libio/tst-cleanup-*.c > > > >I was referring to > > > >elf/tst-array1-static.c > >elf/tst-array5-static.c > >elf/tst-dl-iter-static.c > >elf/tst-dst-static.c > >elf/tst-leaks1-static.c > >elf/tst-libc_dlvsym-static.c > >elf/tst-linkall-static.c > >elf/tst-ptrguard1-static.c > >elf/tst-single_threaded-pthread-static.c > >elf/tst-single_threaded-static.c > >elf/tst-stackguard1-static.c > >elf/tst-tls1-static.c > >elf/tst-tls2-static.c > >elf/tst-tls9-static.c > >elf/tst-tlsalign-extern-static.c > >elf/tst-tlsalign-static.c > >gmon/tst-gmon-static.c > >gmon/tst-profile-static.c > >localedata/bug-setlocale1-static.c > >localedata/tst-langinfo-newlocale-static.c > >localedata/tst-langinfo-setlocale-static.c > >localedata/tst-langinfo-static.c > >malloc/tst-malloc-usable-static.c > >math/test-fpucw-ieee-static.c > >math/test-fpucw-static.c > >math/test-signgam-uchar-init-static.c > >math/test-signgam-uchar-static.c > >math/test-signgam-uint-init-static.c > >math/test-signgam-uint-static.c > >math/test-signgam-ullong-init-static.c > >math/test-signgam-ullong-static.c > >nptl/tst-mutex8-static.c > >nptl/tst-mutexpi8-static.c > >nptl/tst-sem11-static.c > >nptl/tst-sem12-static.c > >nptl/tst-setuid1-static.c > >nptl/tst-stackguard1-static.c > >nss/tst-nss-static.c > >posix/tst-exec-static.c > >posix/tst-spawn-static.c > >setjmp/tst-setjmp-static.c > > > >> >2. We need to add the static test to both tests and tests-static. > >> > >> tests-static suffices. I have checked some tests-static usage in other > >> directories. > > > >There are > > > >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > > tst-sigsetjmp tst-setjmp-static > >tests-static := tst-setjmp-static > > > >They should be replaced by something like > > > >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > > tst-sigsetjmp > >tests-static-add := tst-setjmp-static > > Re-checking, the tst-cleanup* targets are in tests-special so `make tests` will build them. > If a tests-static target is not in tests-internal/tests-special, looks like it needs to be in tests. > > As is, I think my usage is correct. > The current glibc convention is to use [hjl@gnu-cfl-2 x86-glibc]$ cat elf/tst-tls9-static.c #include "tst-tls9.c" [hjl@gnu-cfl-2 x86-glibc]$ to test both dynamic and static libc. If we want to use a single source, we should create a framework to cover all such tests. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-05 21:58 ` H.J. Lu @ 2021-04-06 21:46 ` Fangrui Song 2021-04-09 22:36 ` Fāng-ruì Sòng 2021-04-16 13:00 ` H.J. Lu 0 siblings, 2 replies; 40+ messages in thread From: Fangrui Song @ 2021-04-06 21:46 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On 2021-04-05, H.J. Lu wrote: >On Mon, Apr 5, 2021 at 2:03 PM Fangrui Song <maskray@google.com> wrote: >> >> On 2021-04-05, H.J. Lu wrote: >> >On Mon, Apr 5, 2021 at 11:17 AM Fangrui Song <maskray@google.com> wrote: >> >> >> >> On 2021-04-04, H.J. Lu wrote: >> >> >On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> On 2021-04-03, H.J. Lu wrote: >> >> >> >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> >> >> >> >> >> >> On 2021-04-02, H.J. Lu wrote: >> >> >> >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> >> >> >> >> On 2021-04-01, H.J. Lu wrote: >> >> >> >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: >> >> >> >> >> >> >> >> >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined >> >> >> >> >> >> variables will be retained by the linker. >> >> >> >> >> >> >> >> >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> >> >> >> >> >> will not be optimized out; 'retain' prevents section garbage collection >> >> >> >> >> >> if the linker support SHF_GNU_RETAIN. >> >> >> >> >> >> >> >> >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> >> >> >> >> >> identifier name sections to be GCed even if there are live >> >> >> >> >> >> __start_/__stop_ references. >> >> >> >> >> >> >> >> >> >> >> >> Without the change, there are some static linking problems, e.g. >> >> >> >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> >> >> >> >> >> stdout is not flushed on exit. >> >> >> >> >> >> >> >> >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> >> >> >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> >> >> >> >> >> --- >> >> >> >> >> >> Changes in v1 -> v2: >> >> >> >> >> >> * Define attribute_used_retain_section >> >> >> >> >> >> Changes in v2 -> v3: >> >> >> >> >> >> * Use attribute_used_retain instead attribute_used_retain_section >> >> >> >> >> >> Changes in v3 -> v4: >> >> >> >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests >> >> >> >> >> >> Changes in v4 -> v5: >> >> >> >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported >> >> >> >> >> >> * Rename *gcc_retain* to *gnu_retain* >> >> >> >> >> >> --- >> >> >> >> >> >> config.h.in | 3 +++ >> >> >> >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ >> >> >> >> >> >> configure.ac | 21 +++++++++++++++ >> >> >> >> >> >> include/libc-symbols.h | 14 +++++++--- >> >> >> >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ >> >> >> >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ >> >> >> >> >> >> libio/tst-cleanup.exp | 1 + >> >> >> >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) >> >> >> >> >> >> create mode 100644 libio/tst-cleanup.c >> >> >> >> >> >> create mode 100644 libio/tst-cleanup.exp >> >> >> >> >> >> >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> >> >> >> >> index ca1547ae67..96a08c7757 100644 >> >> >> >> >> >> --- a/config.h.in >> >> >> >> >> >> +++ b/config.h.in >> >> >> >> >> >> @@ -187,6 +187,9 @@ >> >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ >> >> >> >> >> >> #undef HAVE_GCC_IFUNC >> >> >> >> >> >> >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> >> >> >> >> +#undef HAVE_GNU_RETAIN >> >> >> >> >> >> + >> >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ >> >> >> >> >> >> #undef HAVE_EHDR_START >> >> >> >> >> >> >> >> >> >> >> >> diff --git a/configure b/configure >> >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> >> >> >> >> --- a/configure >> >> >> >> >> >> +++ b/configure >> >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi >> >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> >> >> >> >> + $as_echo_n "(cached) " >&6 >> >> >> >> >> >> +else >> >> >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> >> >> +EOF >> >> >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> >> >> >> >> + 2>&5 ; then >> >> >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> >> >> +fi >> >> >> >> >> >> +rm -f conftest* >> >> >> >> >> >> +fi >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> >> >> >> >> + >> >> >> >> >> >> +fi >> >> >> >> >> >> +config_vars="$config_vars >> >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> >> >> >> >> + >> >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi >> >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> >> >> >> >> +libc_linker_feature=no >> >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then >> >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> >> >> >> >> + if test -n "$libc_linker_check"; then >> >> >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> >> >> +int _start (void) { return 42; } >> >> >> >> >> >> +EOF >> >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c >> >> >> >> >> >> + 1>&5' >> >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> >> >> >> >> + (eval $ac_try) 2>&5 >> >> >> >> >> >> + ac_status=$? >> >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> >> >> >> >> + test $ac_status = 0; }; } >> >> >> >> >> >> + then >> >> >> >> >> >> + libc_linker_feature=yes >> >> >> >> >> >> + fi >> >> >> >> >> >> + rm -f conftest* >> >> >> >> >> >> + fi >> >> >> >> >> >> +fi >> >> >> >> >> >> +if test $libc_linker_feature = yes; then >> >> >> >> >> >> + libc_cv_z_start_stop_gc=yes >> >> >> >> >> >> +else >> >> >> >> >> >> + libc_cv_z_start_stop_gc=no >> >> >> >> >> >> +fi >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> +config_vars="$config_vars >> >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> >> >> >> >> + >> >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> >> >> >> >> libc_linker_feature=no >> >> >> >> >> >> diff --git a/configure.ac b/configure.ac >> >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 >> >> >> >> >> >> --- a/configure.ac >> >> >> >> >> >> +++ b/configure.ac >> >> >> >> >> >> @@ -707,6 +707,23 @@ fi >> >> >> >> >> >> rm -f conftest*]) >> >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> >> >> >> >> + libc_cv_gnu_retain, [dnl >> >> >> >> >> >> +cat > conftest.c <<EOF >> >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> >> >> +EOF >> >> >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> >> >> +fi >> >> >> >> >> >> +rm -f conftest*]) >> >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> >> >> >> >> +fi >> >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> >> >> >> >> + >> >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> >> >> >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> >> >> >> >> + >> >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> >> >> >> >> [-Wl,--no-dynamic-linker], >> >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], >> >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 >> >> >> >> >> >> --- a/include/libc-symbols.h >> >> >> >> >> >> +++ b/include/libc-symbols.h >> >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> >> >> >> >> >> >> >> >> */ >> >> >> >> >> >> >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> >> >> >> >> +#else >> >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> >> >> >> >> +#endif >> >> >> >> >> >> + >> >> >> >> >> >> /* Symbol set support macros. */ >> >> >> >> >> >> >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") >> >> >> >> >> >> /* When building a shared library, make the set section writable, >> >> >> >> >> >> because it will need to be relocated at run time anyway. */ >> >> >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> >> >> #else >> >> >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> >> >> #endif >> >> >> >> >> >> >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> >> >> >> >> index 12ce41038f..c9c232ebc2 100644 >> >> >> >> >> >> --- a/libio/Makefile >> >> >> >> >> >> +++ b/libio/Makefile >> >> >> >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) >> >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> >> >> >> >> $(objpfx)tst-bz24228-mem.out >> >> >> >> >> >> endif >> >> >> >> >> >> + >> >> >> >> >> >> +tests += tst-cleanup-default >> >> >> >> >> >> +tests-static += tst-cleanup-default >> >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out >> >> >> >> >> > >> >> >> >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. >> >> >> >> >> >> >> >> >> >> Added. >> >> >> >> >> >> >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> >> >> >> >> + >> >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out >> >> >> >> >> > >> >> >> >> >> >Same here. >> >> >> >> >> >> >> >> >> >> Added. >> >> >> >> >> >> >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc >> >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> >> >> >> +endif >> >> >> >> >> >> endif >> >> >> >> >> >> >> >> >> >> >> >> include ../Rules >> >> >> >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> >> >> >> endif >> >> >> >> >> >> >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> >> + >> >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> >> + >> >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> >> >> >> >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> >> >> >> >> $(common-objpfx)libio/; \ >> >> >> >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> >> >> >> >> >> new file mode 100644 >> >> >> >> >> >> index 0000000000..7f0a34a91e >> >> >> >> >> >> --- /dev/null >> >> >> >> >> >> +++ b/libio/tst-cleanup.c >> >> >> >> >> >> @@ -0,0 +1,33 @@ >> >> >> >> >> > >> >> >> >> >> >Please add a comment saying that test --gc-sections. >> >> >> >> >> >> >> >> >> >> OK, added. >> >> >> >> >> >> >> >> >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> >> >> >> >> >> + This file is part of the GNU C Library. >> >> >> >> >> >> + >> >> >> >> >> >> + The GNU C Library is free software; you can redistribute it and/or >> >> >> >> >> >> + modify it under the terms of the GNU Lesser General Public >> >> >> >> >> >> + License as published by the Free Software Foundation; either >> >> >> >> >> >> + version 2.1 of the License, or (at your option) any later version. >> >> >> >> >> >> + >> >> >> >> >> >> + The GNU C Library is distributed in the hope that it will be useful, >> >> >> >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> >> >> >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> >> >> >> >> >> + Lesser General Public License for more details. >> >> >> >> >> >> + >> >> >> >> >> >> + You should have received a copy of the GNU Lesser General Public >> >> >> >> >> >> + License along with the GNU C Library; if not, see >> >> >> >> >> >> + <https://www.gnu.org/licenses/>. */ >> >> >> >> >> >> + >> >> >> >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> >> >> >> >> >> + >> >> >> >> >> >> +#include <stdio.h> >> >> >> >> >> >> +#include <stdlib.h> >> >> >> >> >> >> + >> >> >> >> >> >> +void >> >> >> >> >> >> +hook (void) >> >> >> >> >> >> +{ >> >> >> >> >> >> + puts ("hello"); >> >> >> >> >> >> +} >> >> >> >> >> >> + >> >> >> >> >> >> +int >> >> >> >> >> >> +main (void) >> >> >> >> >> >> +{ >> >> >> >> >> >> + atexit (hook); >> >> >> >> >> >> +} >> >> >> >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> >> >> >> >> >> new file mode 100644 >> >> >> >> >> >> index 0000000000..ce01362503 >> >> >> >> >> >> --- /dev/null >> >> >> >> >> >> +++ b/libio/tst-cleanup.exp >> >> >> >> >> >> @@ -0,0 +1 @@ >> >> >> >> >> >> +hello >> >> >> >> >> >> -- >> >> >> >> >> >> 2.31.0.291.g576ba9dcdaf-goog >> >> >> >> >> >> >> >> >> >> >> > >> >> >> >> >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in >> >> >> >> >> index ca1547ae67..96a08c7757 100644 >> >> >> >> >> --- a/config.h.in >> >> >> >> >> +++ b/config.h.in >> >> >> >> >> @@ -187,6 +187,9 @@ >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ >> >> >> >> >> #undef HAVE_GCC_IFUNC >> >> >> >> >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ >> >> >> >> >> +#undef HAVE_GNU_RETAIN >> >> >> >> >> + >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ >> >> >> >> >> #undef HAVE_EHDR_START >> >> >> >> >> >> >> >> >> >> diff --git a/configure b/configure >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 >> >> >> >> >> --- a/configure >> >> >> >> >> +++ b/configure >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : >> >> >> >> >> + $as_echo_n "(cached) " >&6 >> >> >> >> >> +else >> >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> >> +EOF >> >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> >> >> >> >> + 2>&5 ; then >> >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> >> +fi >> >> >> >> >> +rm -f conftest* >> >> >> >> >> +fi >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h >> >> >> >> >> + >> >> >> >> >> +fi >> >> >> >> >> +config_vars="$config_vars >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" >> >> >> >> >> + >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> >> >> >> >> +libc_linker_feature=no >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> >> >> >> >> + if test -n "$libc_linker_check"; then >> >> >> >> >> + cat > conftest.c <<EOF >> >> >> >> >> +int _start (void) { return 42; } >> >> >> >> >> +EOF >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c >> >> >> >> >> + 1>&5' >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> >> >> >> >> + (eval $ac_try) 2>&5 >> >> >> >> >> + ac_status=$? >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> >> >> >> >> + test $ac_status = 0; }; } >> >> >> >> >> + then >> >> >> >> >> + libc_linker_feature=yes >> >> >> >> >> + fi >> >> >> >> >> + rm -f conftest* >> >> >> >> >> + fi >> >> >> >> >> +fi >> >> >> >> >> +if test $libc_linker_feature = yes; then >> >> >> >> >> + libc_cv_z_start_stop_gc=yes >> >> >> >> >> +else >> >> >> >> >> + libc_cv_z_start_stop_gc=no >> >> >> >> >> +fi >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } >> >> >> >> >> +config_vars="$config_vars >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> >> >> >> >> + >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> >> >> >> >> libc_linker_feature=no >> >> >> >> >> diff --git a/configure.ac b/configure.ac >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 >> >> >> >> >> --- a/configure.ac >> >> >> >> >> +++ b/configure.ac >> >> >> >> >> @@ -707,6 +707,23 @@ fi >> >> >> >> >> rm -f conftest*]) >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) >> >> >> >> >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], >> >> >> >> >> + libc_cv_gnu_retain, [dnl >> >> >> >> >> +cat > conftest.c <<EOF >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> >> >> >> >> +EOF >> >> >> >> >> +libc_cv_gnu_retain=no >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then >> >> >> >> >> + libc_cv_gnu_retain=yes >> >> >> >> >> +fi >> >> >> >> >> +rm -f conftest*]) >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) >> >> >> >> >> +fi >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) >> >> >> >> >> + >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) >> >> >> >> >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> >> >> >> >> + >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> >> >> >> >> [-Wl,--no-dynamic-linker], >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 >> >> >> >> >> --- a/include/libc-symbols.h >> >> >> >> >> +++ b/include/libc-symbols.h >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") >> >> >> >> >> >> >> >> >> >> */ >> >> >> >> >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> >> >> >> >> +#else >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) >> >> >> >> >> +#endif >> >> >> >> >> + >> >> >> >> >> /* Symbol set support macros. */ >> >> >> >> >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") >> >> >> >> >> /* When building a shared library, make the set section writable, >> >> >> >> >> because it will need to be relocated at run time anyway. */ >> >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> >> #else >> >> >> >> >> # define _elf_set_element(set, symbol) \ >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> >> >> >> >> #endif >> >> >> >> >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> >> >> >> index 12ce41038f..ad0d53bb49 100644 >> >> >> >> >> --- a/libio/Makefile >> >> >> >> >> +++ b/libio/Makefile >> >> >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> >> >> >> $(objpfx)tst-bz24228-mem.out >> >> >> >> >> endif >> >> >> >> >> + >> >> >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static >> >> >> >> >> +tests-static += tst-cleanup-default-static >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections >> >> >> >> >> + >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ >> >> >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> >> >> +endif >> >> >> >> >> endif >> >> >> >> >> >> >> >> >> >> include ../Rules >> >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> >> >> endif >> >> >> >> >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> + >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> >> >> >> >> + cmp $^ > $@; \ >> >> >> >> >> + $(evaluate-test) >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c >> >> >> >> >> + $(compile.c) -o $@ >> >> >> >> > >> >> >> >> >Please add a separate .c file for each test to get the correct dependency. >> >> >> >> >> >> >> >> Changed this block to: >> >> >> >> >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> >> endif >> >> >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c >> >> >> >> + cp $< $@ >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c >> >> >> >> + cp $< $@ >> >> >> >> + >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> >> >> >> + $(compile.c) -o $@ >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c >> >> >> >> + cp $< $@ >> >> >> >> + >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c >> >> >> >> + cp $< $@ >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out >> >> >> >> + cmp $^ > $@; \ >> >> >> >> + $(evaluate-test) >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c >> >> >> >> + cp $< $@ >> >> >> >> + >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> >> >> $(common-objpfx)libio/; \ >> >> >> >> >> >> >> > >> >> >> >"make clean" doesn't remove the generated files. The standard way in glibc >> >> >> >is to add a *-static.c source. >> >> >> >> >> >> I'll use .INTERMEDIATE and $(eval $(call ..)) >> >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile >> >> >> index 12ce41038f..a9b44f04df 100644 >> >> >> --- a/libio/Makefile >> >> >> +++ b/libio/Makefile >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> >> >> $(objpfx)tst-bz24228-mem.out >> >> >> endif >> >> >> + >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static >> >> >> +tests-static += tst-cleanup-default-static >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections >> >> >> + >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc >> >> >> +endif >> >> >> endif >> >> >> >> >> >> include ../Rules >> >> >> @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> >> >> endif >> >> >> >> >> >> +define gen-tst-cleanup >> >> >> +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out >> >> >> + cmp $$^ > $$@; $$(evaluate-test) >> >> >> +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c >> >> >> + cp $$< $$@ >> >> >> +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c >> >> >> +endef >> >> >> + >> >> >> +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ >> >> >> + $(eval $(call gen-tst-cleanup,$(t)))) >> >> >> + >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> >> >> $(common-objpfx)libio/; \ >> >> > >> >> >There are 2 issues with static tests: >> >> > >> >> >1. A separate static source is needed. >> >> >> >> .INTERMEDIATE perfectly solves the lingering copied source issue. >> >> I don't see lingering libio/tst-cleanup-*.c >> > >> >I was referring to >> > >> >elf/tst-array1-static.c >> >elf/tst-array5-static.c >> >elf/tst-dl-iter-static.c >> >elf/tst-dst-static.c >> >elf/tst-leaks1-static.c >> >elf/tst-libc_dlvsym-static.c >> >elf/tst-linkall-static.c >> >elf/tst-ptrguard1-static.c >> >elf/tst-single_threaded-pthread-static.c >> >elf/tst-single_threaded-static.c >> >elf/tst-stackguard1-static.c >> >elf/tst-tls1-static.c >> >elf/tst-tls2-static.c >> >elf/tst-tls9-static.c >> >elf/tst-tlsalign-extern-static.c >> >elf/tst-tlsalign-static.c >> >gmon/tst-gmon-static.c >> >gmon/tst-profile-static.c >> >localedata/bug-setlocale1-static.c >> >localedata/tst-langinfo-newlocale-static.c >> >localedata/tst-langinfo-setlocale-static.c >> >localedata/tst-langinfo-static.c >> >malloc/tst-malloc-usable-static.c >> >math/test-fpucw-ieee-static.c >> >math/test-fpucw-static.c >> >math/test-signgam-uchar-init-static.c >> >math/test-signgam-uchar-static.c >> >math/test-signgam-uint-init-static.c >> >math/test-signgam-uint-static.c >> >math/test-signgam-ullong-init-static.c >> >math/test-signgam-ullong-static.c >> >nptl/tst-mutex8-static.c >> >nptl/tst-mutexpi8-static.c >> >nptl/tst-sem11-static.c >> >nptl/tst-sem12-static.c >> >nptl/tst-setuid1-static.c >> >nptl/tst-stackguard1-static.c >> >nss/tst-nss-static.c >> >posix/tst-exec-static.c >> >posix/tst-spawn-static.c >> >setjmp/tst-setjmp-static.c >> > >> >> >2. We need to add the static test to both tests and tests-static. >> >> >> >> tests-static suffices. I have checked some tests-static usage in other >> >> directories. >> > >> >There are >> > >> >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ >> > tst-sigsetjmp tst-setjmp-static >> >tests-static := tst-setjmp-static >> > >> >They should be replaced by something like >> > >> >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ >> > tst-sigsetjmp >> >tests-static-add := tst-setjmp-static >> >> Re-checking, the tst-cleanup* targets are in tests-special so `make tests` will build them. >> If a tests-static target is not in tests-internal/tests-special, looks like it needs to be in tests. >> >> As is, I think my usage is correct. >> > >The current glibc convention is to use > >[hjl@gnu-cfl-2 x86-glibc]$ cat elf/tst-tls9-static.c >#include "tst-tls9.c" >[hjl@gnu-cfl-2 x86-glibc]$ > >to test both dynamic and static libc. If we want to use a single >source, we should create >a framework to cover all such tests. OK. Dropped cp $< $@ and .INTERMEDIATE From e937ae26a4a9a8ff6b1198f347f0b141a9285305 Mon Sep 17 00:00:00 2001 From: Fangrui Song <maskray@google.com> Date: Tue, 6 Apr 2021 14:45:01 -0700 Subject: [PATCH] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit So that text_set_element/data_set_element/bss_set_element defined variables will be retained by the linker. Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable will not be optimized out; 'retain' prevents section garbage collection if the linker support SHF_GNU_RETAIN. GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C identifier name sections to be GCed even if there are live __start_/__stop_ references. Without the change, there are some static linking problems, e.g. _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so stdout is not flushed on exit. Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). --- config.h.in | 3 ++ configure | 59 ++++++++++++++++++++++ configure.ac | 21 ++++++++ include/libc-symbols.h | 14 +++-- libio/Makefile | 28 ++++++++++ libio/tst-cleanup-default-static.c | 1 + libio/tst-cleanup-default.c | 1 + libio/tst-cleanup-nostart-stop-gc-static.c | 1 + libio/tst-cleanup-nostart-stop-gc.c | 1 + libio/tst-cleanup-start-stop-gc-static.c | 1 + libio/tst-cleanup-start-stop-gc.c | 1 + libio/tst-cleanup.c | 34 +++++++++++++ libio/tst-cleanup.exp | 1 + 13 files changed, 162 insertions(+), 4 deletions(-) create mode 100644 libio/tst-cleanup-default-static.c create mode 100644 libio/tst-cleanup-default.c create mode 100644 libio/tst-cleanup-nostart-stop-gc-static.c create mode 100644 libio/tst-cleanup-nostart-stop-gc.c create mode 100644 libio/tst-cleanup-start-stop-gc-static.c create mode 100644 libio/tst-cleanup-start-stop-gc.c create mode 100644 libio/tst-cleanup.c create mode 100644 libio/tst-cleanup.exp diff --git a/config.h.in b/config.h.in index ca1547ae67..96a08c7757 100644 --- a/config.h.in +++ b/config.h.in @@ -187,6 +187,9 @@ /* Define if gcc supports attribute ifunc. */ #undef HAVE_GCC_IFUNC +/* Define if CC supports attribute retain. */ +#undef HAVE_GNU_RETAIN + /* Define if the linker defines __ehdr_start. */ #undef HAVE_EHDR_START diff --git a/configure b/configure index fcf43bf7de..e64b7f8efe 100755 --- a/configure +++ b/configure @@ -4105,6 +4105,31 @@ fi $as_echo "$libc_cv_textrel_ifunc" >&6; } +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 +$as_echo_n "checking for GNU attribute retain support... " >&6; } +if ${libc_cv_gnu_retain+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gnu_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ + 2>&5 ; then + libc_cv_gnu_retain=yes +fi +rm -f conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 +$as_echo "$libc_cv_gnu_retain" >&6; } +if test $libc_cv_gnu_retain = yes; then + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h + +fi +config_vars="$config_vars +have-gnu-retain = $libc_cv_gnu_retain" + # Check if gcc warns about alias for function with incompatible types. { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } @@ -5871,6 +5896,40 @@ fi $as_echo "$libc_linker_feature" >&6; } +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } +libc_linker_feature=no +if test x"$gnu_ld" = x"yes"; then + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` + if test -n "$libc_linker_check"; then + cat > conftest.c <<EOF +int _start (void) { return 42; } +EOF + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp + -Wl,-z,start-stop-gc -nostdlib -nostartfiles + -fPIC -shared -o conftest.so conftest.c + 1>&5' + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 + (eval $ac_try) 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; }; } + then + libc_linker_feature=yes + fi + rm -f conftest* + fi +fi +if test $libc_linker_feature = yes; then + libc_cv_z_start_stop_gc=yes +else + libc_cv_z_start_stop_gc=no +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 +$as_echo "$libc_linker_feature" >&6; } +config_vars="$config_vars +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } libc_linker_feature=no diff --git a/configure.ac b/configure.ac index fce967f2c2..cc47e56e82 100644 --- a/configure.ac +++ b/configure.ac @@ -707,6 +707,23 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_textrel_ifunc) +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. +AC_CACHE_CHECK([for GNU attribute retain support], + libc_cv_gnu_retain, [dnl +cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gnu_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ + 2>&AS_MESSAGE_LOG_FD ; then + libc_cv_gnu_retain=yes +fi +rm -f conftest*]) +if test $libc_cv_gnu_retain = yes; then + AC_DEFINE(HAVE_GNU_RETAIN) +fi +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) + # Check if gcc warns about alias for function with incompatible types. AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], libc_cv_gcc_incompatible_alias, [dnl @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) AC_SUBST(libc_cv_z_execstack) +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) + LIBC_LINKER_FEATURE([--no-dynamic-linker], [-Wl,--no-dynamic-linker], [libc_cv_no_dynamic_linker=yes], diff --git a/include/libc-symbols.h b/include/libc-symbols.h index 546fc26a7b..127ea656c2 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -352,6 +352,12 @@ for linking") \f */ +#ifdef HAVE_GNU_RETAIN +# define attribute_used_retain __attribute__ ((__used__, __retain__)) +#else +# define attribute_used_retain __attribute__ ((__used__)) +#endif + /* Symbol set support macros. */ /* Make SYMBOL, which is in the text segment, an element of SET. */ @@ -367,12 +373,12 @@ for linking") /* When building a shared library, make the set section writable, because it will need to be relocated at run time anyway. */ # define _elf_set_element(set, symbol) \ - static const void *__elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *__elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #else # define _elf_set_element(set, symbol) \ - static const void *const __elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *const __elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #endif /* Define SET as a symbol set. This may be required (it is in a.out) to diff --git a/libio/Makefile b/libio/Makefile index 12ce41038f..ed0ce4ee81 100644 --- a/libio/Makefile +++ b/libio/Makefile @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ $(objpfx)tst-bz24228-mem.out endif + +tests += tst-cleanup-default tst-cleanup-default-static +tests-static += tst-cleanup-default-static +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections + +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc +endif endif include ../Rules @@ -224,6 +244,14 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) $(objpfx)tst-wfile-sync.out: $(gen-locales) endif +define gen-tst-cleanup +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out + cmp $$^ > $$@; $$(evaluate-test) +endef + +$(foreach t,default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ + $(eval $(call gen-tst-cleanup,$(t)))) + $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ $(common-objpfx)libio/; \ diff --git a/libio/tst-cleanup-default-static.c b/libio/tst-cleanup-default-static.c new file mode 100644 index 0000000000..c39956e2a8 --- /dev/null +++ b/libio/tst-cleanup-default-static.c @@ -0,0 +1 @@ +#include "tst-cleanup.c" diff --git a/libio/tst-cleanup-default.c b/libio/tst-cleanup-default.c new file mode 100644 index 0000000000..c39956e2a8 --- /dev/null +++ b/libio/tst-cleanup-default.c @@ -0,0 +1 @@ +#include "tst-cleanup.c" diff --git a/libio/tst-cleanup-nostart-stop-gc-static.c b/libio/tst-cleanup-nostart-stop-gc-static.c new file mode 100644 index 0000000000..c39956e2a8 --- /dev/null +++ b/libio/tst-cleanup-nostart-stop-gc-static.c @@ -0,0 +1 @@ +#include "tst-cleanup.c" diff --git a/libio/tst-cleanup-nostart-stop-gc.c b/libio/tst-cleanup-nostart-stop-gc.c new file mode 100644 index 0000000000..c39956e2a8 --- /dev/null +++ b/libio/tst-cleanup-nostart-stop-gc.c @@ -0,0 +1 @@ +#include "tst-cleanup.c" diff --git a/libio/tst-cleanup-start-stop-gc-static.c b/libio/tst-cleanup-start-stop-gc-static.c new file mode 100644 index 0000000000..c39956e2a8 --- /dev/null +++ b/libio/tst-cleanup-start-stop-gc-static.c @@ -0,0 +1 @@ +#include "tst-cleanup.c" diff --git a/libio/tst-cleanup-start-stop-gc.c b/libio/tst-cleanup-start-stop-gc.c new file mode 100644 index 0000000000..c39956e2a8 --- /dev/null +++ b/libio/tst-cleanup-start-stop-gc.c @@ -0,0 +1 @@ +#include "tst-cleanup.c" diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c new file mode 100644 index 0000000000..837feac164 --- /dev/null +++ b/libio/tst-cleanup.c @@ -0,0 +1,34 @@ +/* Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* Test that stdout is flushed after atexit callbacks were run, even if the + * executable is linked with --gc-sections. */ + +#include <stdio.h> +#include <stdlib.h> + +void +hook (void) +{ + puts ("hello"); +} + +int +main (void) +{ + atexit (hook); +} diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp new file mode 100644 index 0000000000..ce01362503 --- /dev/null +++ b/libio/tst-cleanup.exp @@ -0,0 +1 @@ +hello -- 2.31.0.208.g409f899ff0-goog ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-06 21:46 ` Fangrui Song @ 2021-04-09 22:36 ` Fāng-ruì Sòng 2021-04-16 3:51 ` Fāng-ruì Sòng 2021-04-16 13:00 ` H.J. Lu 1 sibling, 1 reply; 40+ messages in thread From: Fāng-ruì Sòng @ 2021-04-09 22:36 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On Tue, Apr 6, 2021 at 2:46 PM Fangrui Song <maskray@google.com> wrote: > > > On 2021-04-05, H.J. Lu wrote: > >On Mon, Apr 5, 2021 at 2:03 PM Fangrui Song <maskray@google.com> wrote: > >> > >> On 2021-04-05, H.J. Lu wrote: > >> >On Mon, Apr 5, 2021 at 11:17 AM Fangrui Song <maskray@google.com> wrote: > >> >> > >> >> On 2021-04-04, H.J. Lu wrote: > >> >> >On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> > >> >> >> On 2021-04-03, H.J. Lu wrote: > >> >> >> >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: > >> >> >> >> > >> >> >> >> > >> >> >> >> On 2021-04-02, H.J. Lu wrote: > >> >> >> >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> >> >> > >> >> >> >> >> On 2021-04-01, H.J. Lu wrote: > >> >> >> >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> >> >> >> > >> >> >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined > >> >> >> >> >> >> variables will be retained by the linker. > >> >> >> >> >> >> > >> >> >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> >> >> >> >> >> will not be optimized out; 'retain' prevents section garbage collection > >> >> >> >> >> >> if the linker support SHF_GNU_RETAIN. > >> >> >> >> >> >> > >> >> >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> >> >> >> >> >> identifier name sections to be GCed even if there are live > >> >> >> >> >> >> __start_/__stop_ references. > >> >> >> >> >> >> > >> >> >> >> >> >> Without the change, there are some static linking problems, e.g. > >> >> >> >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> >> >> >> >> >> stdout is not flushed on exit. > >> >> >> >> >> >> > >> >> >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> >> >> >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> >> >> >> >> >> --- > >> >> >> >> >> >> Changes in v1 -> v2: > >> >> >> >> >> >> * Define attribute_used_retain_section > >> >> >> >> >> >> Changes in v2 -> v3: > >> >> >> >> >> >> * Use attribute_used_retain instead attribute_used_retain_section > >> >> >> >> >> >> Changes in v3 -> v4: > >> >> >> >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> >> >> >> >> >> Changes in v4 -> v5: > >> >> >> >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > >> >> >> >> >> >> * Rename *gcc_retain* to *gnu_retain* > >> >> >> >> >> >> --- > >> >> >> >> >> >> config.h.in | 3 +++ > >> >> >> >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > >> >> >> >> >> >> configure.ac | 21 +++++++++++++++ > >> >> >> >> >> >> include/libc-symbols.h | 14 +++++++--- > >> >> >> >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ > >> >> >> >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > >> >> >> >> >> >> libio/tst-cleanup.exp | 1 + > >> >> >> >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) > >> >> >> >> >> >> create mode 100644 libio/tst-cleanup.c > >> >> >> >> >> >> create mode 100644 libio/tst-cleanup.exp > >> >> >> >> >> >> > >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in > >> >> >> >> >> >> index ca1547ae67..96a08c7757 100644 > >> >> >> >> >> >> --- a/config.h.in > >> >> >> >> >> >> +++ b/config.h.in > >> >> >> >> >> >> @@ -187,6 +187,9 @@ > >> >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ > >> >> >> >> >> >> #undef HAVE_GCC_IFUNC > >> >> >> >> >> >> > >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ > >> >> >> >> >> >> +#undef HAVE_GNU_RETAIN > >> >> >> >> >> >> + > >> >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ > >> >> >> >> >> >> #undef HAVE_EHDR_START > >> >> >> >> >> >> > >> >> >> >> >> >> diff --git a/configure b/configure > >> >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> >> >> >> >> --- a/configure > >> >> >> >> >> >> +++ b/configure > >> >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi > >> >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> >> >> >> >> > >> >> >> >> >> >> > >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> >> >> >> >> + $as_echo_n "(cached) " >&6 > >> >> >> >> >> >> +else > >> >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> >> +EOF > >> >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> >> >> >> >> + 2>&5 ; then > >> >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +rm -f conftest* > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> >> >> >> >> + > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> >> >> >> >> + > >> >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi > >> >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> >> > >> >> >> >> >> >> > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> >> >> >> >> +libc_linker_feature=no > >> >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> >> >> >> >> + if test -n "$libc_linker_check"; then > >> >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> >> +int _start (void) { return 42; } > >> >> >> >> >> >> +EOF > >> >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> >> >> >> >> + 1>&5' > >> >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> >> >> >> >> + (eval $ac_try) 2>&5 > >> >> >> >> >> >> + ac_status=$? > >> >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> >> >> >> >> + test $ac_status = 0; }; } > >> >> >> >> >> >> + then > >> >> >> >> >> >> + libc_linker_feature=yes > >> >> >> >> >> >> + fi > >> >> >> >> >> >> + rm -f conftest* > >> >> >> >> >> >> + fi > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +if test $libc_linker_feature = yes; then > >> >> >> >> >> >> + libc_cv_z_start_stop_gc=yes > >> >> >> >> >> >> +else > >> >> >> >> >> >> + libc_cv_z_start_stop_gc=no > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> >> >> >> >> + > >> >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> >> >> >> >> libc_linker_feature=no > >> >> >> >> >> >> diff --git a/configure.ac b/configure.ac > >> >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 > >> >> >> >> >> >> --- a/configure.ac > >> >> >> >> >> >> +++ b/configure.ac > >> >> >> >> >> >> @@ -707,6 +707,23 @@ fi > >> >> >> >> >> >> rm -f conftest*]) > >> >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> >> >> >> >> > >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> >> >> >> >> + libc_cv_gnu_retain, [dnl > >> >> >> >> >> >> +cat > conftest.c <<EOF > >> >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> >> +EOF > >> >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +rm -f conftest*]) > >> >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> >> >> >> >> + > >> >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) > >> >> >> >> >> >> > >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> >> >> >> >> + > >> >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> >> >> >> >> [-Wl,--no-dynamic-linker], > >> >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], > >> >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 > >> >> >> >> >> >> --- a/include/libc-symbols.h > >> >> >> >> >> >> +++ b/include/libc-symbols.h > >> >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") > >> >> >> >> >> >> > >> >> >> >> >> >> */ > >> >> >> >> >> >> > >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN > >> >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> >> >> >> >> +#else > >> >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> >> >> >> >> +#endif > >> >> >> >> >> >> + > >> >> >> >> >> >> /* Symbol set support macros. */ > >> >> >> >> >> >> > >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") > >> >> >> >> >> >> /* When building a shared library, make the set section writable, > >> >> >> >> >> >> because it will need to be relocated at run time anyway. */ > >> >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> >> #else > >> >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> >> #endif > >> >> >> >> >> >> > >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> >> >> >> index 12ce41038f..c9c232ebc2 100644 > >> >> >> >> >> >> --- a/libio/Makefile > >> >> >> >> >> >> +++ b/libio/Makefile > >> >> >> >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> >> >> >> endif > >> >> >> >> >> >> + > >> >> >> >> >> >> +tests += tst-cleanup-default > >> >> >> >> >> >> +tests-static += tst-cleanup-default > >> >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >> >> >> >> >> > > >> >> >> >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > >> >> >> >> >> > >> >> >> >> >> Added. > >> >> >> >> >> > >> >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> >> >> >> + > >> >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >> >> >> >> >> > > >> >> >> >> >> >Same here. > >> >> >> >> >> > >> >> >> >> >> Added. > >> >> >> >> >> > >> >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> >> >> +endif > >> >> >> >> >> >> endif > >> >> >> >> >> >> > >> >> >> >> >> >> include ../Rules > >> >> >> >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> >> >> >> endif > >> >> >> >> >> >> > >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> >> + > >> >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> >> + > >> >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > >> >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> >> > >> >> >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> >> >> >> $(common-objpfx)libio/; \ > >> >> >> >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > >> >> >> >> >> >> new file mode 100644 > >> >> >> >> >> >> index 0000000000..7f0a34a91e > >> >> >> >> >> >> --- /dev/null > >> >> >> >> >> >> +++ b/libio/tst-cleanup.c > >> >> >> >> >> >> @@ -0,0 +1,33 @@ > >> >> >> >> >> > > >> >> >> >> >> >Please add a comment saying that test --gc-sections. > >> >> >> >> >> > >> >> >> >> >> OK, added. > >> >> >> >> >> > >> >> >> >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. > >> >> >> >> >> >> + This file is part of the GNU C Library. > >> >> >> >> >> >> + > >> >> >> >> >> >> + The GNU C Library is free software; you can redistribute it and/or > >> >> >> >> >> >> + modify it under the terms of the GNU Lesser General Public > >> >> >> >> >> >> + License as published by the Free Software Foundation; either > >> >> >> >> >> >> + version 2.1 of the License, or (at your option) any later version. > >> >> >> >> >> >> + > >> >> >> >> >> >> + The GNU C Library is distributed in the hope that it will be useful, > >> >> >> >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of > >> >> >> >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > >> >> >> >> >> >> + Lesser General Public License for more details. > >> >> >> >> >> >> + > >> >> >> >> >> >> + You should have received a copy of the GNU Lesser General Public > >> >> >> >> >> >> + License along with the GNU C Library; if not, see > >> >> >> >> >> >> + <https://www.gnu.org/licenses/>. */ > >> >> >> >> >> >> + > >> >> >> >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ > >> >> >> >> >> >> + > >> >> >> >> >> >> +#include <stdio.h> > >> >> >> >> >> >> +#include <stdlib.h> > >> >> >> >> >> >> + > >> >> >> >> >> >> +void > >> >> >> >> >> >> +hook (void) > >> >> >> >> >> >> +{ > >> >> >> >> >> >> + puts ("hello"); > >> >> >> >> >> >> +} > >> >> >> >> >> >> + > >> >> >> >> >> >> +int > >> >> >> >> >> >> +main (void) > >> >> >> >> >> >> +{ > >> >> >> >> >> >> + atexit (hook); > >> >> >> >> >> >> +} > >> >> >> >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > >> >> >> >> >> >> new file mode 100644 > >> >> >> >> >> >> index 0000000000..ce01362503 > >> >> >> >> >> >> --- /dev/null > >> >> >> >> >> >> +++ b/libio/tst-cleanup.exp > >> >> >> >> >> >> @@ -0,0 +1 @@ > >> >> >> >> >> >> +hello > >> >> >> >> >> >> -- > >> >> >> >> >> >> 2.31.0.291.g576ba9dcdaf-goog > >> >> >> >> >> >> > >> >> >> >> >> > > >> >> >> >> >> > >> >> >> >> >> diff --git a/config.h.in b/config.h.in > >> >> >> >> >> index ca1547ae67..96a08c7757 100644 > >> >> >> >> >> --- a/config.h.in > >> >> >> >> >> +++ b/config.h.in > >> >> >> >> >> @@ -187,6 +187,9 @@ > >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ > >> >> >> >> >> #undef HAVE_GCC_IFUNC > >> >> >> >> >> > >> >> >> >> >> +/* Define if CC supports attribute retain. */ > >> >> >> >> >> +#undef HAVE_GNU_RETAIN > >> >> >> >> >> + > >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ > >> >> >> >> >> #undef HAVE_EHDR_START > >> >> >> >> >> > >> >> >> >> >> diff --git a/configure b/configure > >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> >> >> >> --- a/configure > >> >> >> >> >> +++ b/configure > >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi > >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> >> >> >> > >> >> >> >> >> > >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> >> >> >> + $as_echo_n "(cached) " >&6 > >> >> >> >> >> +else > >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> +EOF > >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> >> >> >> + 2>&5 ; then > >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> +fi > >> >> >> >> >> +rm -f conftest* > >> >> >> >> >> +fi > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> >> >> >> + > >> >> >> >> >> +fi > >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> >> >> >> + > >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi > >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> > >> >> >> >> >> > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> >> >> >> +libc_linker_feature=no > >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> >> >> >> + if test -n "$libc_linker_check"; then > >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> +int _start (void) { return 42; } > >> >> >> >> >> +EOF > >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> >> >> >> + 1>&5' > >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> >> >> >> + (eval $ac_try) 2>&5 > >> >> >> >> >> + ac_status=$? > >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> >> >> >> + test $ac_status = 0; }; } > >> >> >> >> >> + then > >> >> >> >> >> + libc_linker_feature=yes > >> >> >> >> >> + fi > >> >> >> >> >> + rm -f conftest* > >> >> >> >> >> + fi > >> >> >> >> >> +fi > >> >> >> >> >> +if test $libc_linker_feature = yes; then > >> >> >> >> >> + libc_cv_z_start_stop_gc=yes > >> >> >> >> >> +else > >> >> >> >> >> + libc_cv_z_start_stop_gc=no > >> >> >> >> >> +fi > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> >> >> >> + > >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> >> >> >> libc_linker_feature=no > >> >> >> >> >> diff --git a/configure.ac b/configure.ac > >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 > >> >> >> >> >> --- a/configure.ac > >> >> >> >> >> +++ b/configure.ac > >> >> >> >> >> @@ -707,6 +707,23 @@ fi > >> >> >> >> >> rm -f conftest*]) > >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> >> >> >> > >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> >> >> >> + libc_cv_gnu_retain, [dnl > >> >> >> >> >> +cat > conftest.c <<EOF > >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> +EOF > >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> +fi > >> >> >> >> >> +rm -f conftest*]) > >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> >> >> >> +fi > >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> >> >> >> + > >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) > >> >> >> >> >> > >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> >> >> >> + > >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> >> >> >> [-Wl,--no-dynamic-linker], > >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], > >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 > >> >> >> >> >> --- a/include/libc-symbols.h > >> >> >> >> >> +++ b/include/libc-symbols.h > >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") > >> >> >> >> >> > >> >> >> >> >> */ > >> >> >> >> >> > >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN > >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> >> >> >> +#else > >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> >> >> >> +#endif > >> >> >> >> >> + > >> >> >> >> >> /* Symbol set support macros. */ > >> >> >> >> >> > >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") > >> >> >> >> >> /* When building a shared library, make the set section writable, > >> >> >> >> >> because it will need to be relocated at run time anyway. */ > >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> #else > >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> #endif > >> >> >> >> >> > >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> >> >> index 12ce41038f..ad0d53bb49 100644 > >> >> >> >> >> --- a/libio/Makefile > >> >> >> >> >> +++ b/libio/Makefile > >> >> >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> >> >> endif > >> >> >> >> >> + > >> >> >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static > >> >> >> >> >> +tests-static += tst-cleanup-default-static > >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> >> >> >> >> + > >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> >> >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> >> +endif > >> >> >> >> >> endif > >> >> >> >> >> > >> >> >> >> >> include ../Rules > >> >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> >> >> endif > >> >> >> >> >> > >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> + > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> > > >> >> >> >> >Please add a separate .c file for each test to get the correct dependency. > >> >> >> >> > >> >> >> >> Changed this block to: > >> >> >> >> > >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> >> endif > >> >> >> >> > >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> + > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> + > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> + > >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> >> $(common-objpfx)libio/; \ > >> >> >> >> > >> >> >> > > >> >> >> >"make clean" doesn't remove the generated files. The standard way in glibc > >> >> >> >is to add a *-static.c source. > >> >> >> > >> >> >> I'll use .INTERMEDIATE and $(eval $(call ..)) > >> >> >> > >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> index 12ce41038f..a9b44f04df 100644 > >> >> >> --- a/libio/Makefile > >> >> >> +++ b/libio/Makefile > >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> endif > >> >> >> + > >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static > >> >> >> +tests-static += tst-cleanup-default-static > >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> >> >> + > >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> +endif > >> >> >> endif > >> >> >> > >> >> >> include ../Rules > >> >> >> @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> endif > >> >> >> > >> >> >> +define gen-tst-cleanup > >> >> >> +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out > >> >> >> + cmp $$^ > $$@; $$(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c > >> >> >> + cp $$< $$@ > >> >> >> +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c > >> >> >> +endef > >> >> >> + > >> >> >> +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ > >> >> >> + $(eval $(call gen-tst-cleanup,$(t)))) > >> >> >> + > >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> $(common-objpfx)libio/; \ > >> >> > > >> >> >There are 2 issues with static tests: > >> >> > > >> >> >1. A separate static source is needed. > >> >> > >> >> .INTERMEDIATE perfectly solves the lingering copied source issue. > >> >> I don't see lingering libio/tst-cleanup-*.c > >> > > >> >I was referring to > >> > > >> >elf/tst-array1-static.c > >> >elf/tst-array5-static.c > >> >elf/tst-dl-iter-static.c > >> >elf/tst-dst-static.c > >> >elf/tst-leaks1-static.c > >> >elf/tst-libc_dlvsym-static.c > >> >elf/tst-linkall-static.c > >> >elf/tst-ptrguard1-static.c > >> >elf/tst-single_threaded-pthread-static.c > >> >elf/tst-single_threaded-static.c > >> >elf/tst-stackguard1-static.c > >> >elf/tst-tls1-static.c > >> >elf/tst-tls2-static.c > >> >elf/tst-tls9-static.c > >> >elf/tst-tlsalign-extern-static.c > >> >elf/tst-tlsalign-static.c > >> >gmon/tst-gmon-static.c > >> >gmon/tst-profile-static.c > >> >localedata/bug-setlocale1-static.c > >> >localedata/tst-langinfo-newlocale-static.c > >> >localedata/tst-langinfo-setlocale-static.c > >> >localedata/tst-langinfo-static.c > >> >malloc/tst-malloc-usable-static.c > >> >math/test-fpucw-ieee-static.c > >> >math/test-fpucw-static.c > >> >math/test-signgam-uchar-init-static.c > >> >math/test-signgam-uchar-static.c > >> >math/test-signgam-uint-init-static.c > >> >math/test-signgam-uint-static.c > >> >math/test-signgam-ullong-init-static.c > >> >math/test-signgam-ullong-static.c > >> >nptl/tst-mutex8-static.c > >> >nptl/tst-mutexpi8-static.c > >> >nptl/tst-sem11-static.c > >> >nptl/tst-sem12-static.c > >> >nptl/tst-setuid1-static.c > >> >nptl/tst-stackguard1-static.c > >> >nss/tst-nss-static.c > >> >posix/tst-exec-static.c > >> >posix/tst-spawn-static.c > >> >setjmp/tst-setjmp-static.c > >> > > >> >> >2. We need to add the static test to both tests and tests-static. > >> >> > >> >> tests-static suffices. I have checked some tests-static usage in other > >> >> directories. > >> > > >> >There are > >> > > >> >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > >> > tst-sigsetjmp tst-setjmp-static > >> >tests-static := tst-setjmp-static > >> > > >> >They should be replaced by something like > >> > > >> >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > >> > tst-sigsetjmp > >> >tests-static-add := tst-setjmp-static > >> > >> Re-checking, the tst-cleanup* targets are in tests-special so `make tests` will build them. > >> If a tests-static target is not in tests-internal/tests-special, looks like it needs to be in tests. > >> > >> As is, I think my usage is correct. > >> > > > >The current glibc convention is to use > > > >[hjl@gnu-cfl-2 x86-glibc]$ cat elf/tst-tls9-static.c > >#include "tst-tls9.c" > >[hjl@gnu-cfl-2 x86-glibc]$ > > > >to test both dynamic and static libc. If we want to use a single > >source, we should create > >a framework to cover all such tests. > > OK. Dropped cp $< $@ and .INTERMEDIATE > > > From e937ae26a4a9a8ff6b1198f347f0b141a9285305 Mon Sep 17 00:00:00 2001 > From: Fangrui Song <maskray@google.com> > Date: Tue, 6 Apr 2021 14:45:01 -0700 > Subject: [PATCH] Set the retain attribute on _elf_set_element if CC supports > [BZ #27492] > MIME-Version: 1.0 > Content-Type: text/plain; charset=UTF-8 > Content-Transfer-Encoding: 8bit > > So that text_set_element/data_set_element/bss_set_element defined > variables will be retained by the linker. > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > will not be optimized out; 'retain' prevents section garbage collection > if the linker support SHF_GNU_RETAIN. > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > identifier name sections to be GCed even if there are live > __start_/__stop_ references. > > Without the change, there are some static linking problems, e.g. > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > stdout is not flushed on exit. > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > --- > config.h.in | 3 ++ > configure | 59 ++++++++++++++++++++++ > configure.ac | 21 ++++++++ > include/libc-symbols.h | 14 +++-- > libio/Makefile | 28 ++++++++++ > libio/tst-cleanup-default-static.c | 1 + > libio/tst-cleanup-default.c | 1 + > libio/tst-cleanup-nostart-stop-gc-static.c | 1 + > libio/tst-cleanup-nostart-stop-gc.c | 1 + > libio/tst-cleanup-start-stop-gc-static.c | 1 + > libio/tst-cleanup-start-stop-gc.c | 1 + > libio/tst-cleanup.c | 34 +++++++++++++ > libio/tst-cleanup.exp | 1 + > 13 files changed, 162 insertions(+), 4 deletions(-) > create mode 100644 libio/tst-cleanup-default-static.c > create mode 100644 libio/tst-cleanup-default.c > create mode 100644 libio/tst-cleanup-nostart-stop-gc-static.c > create mode 100644 libio/tst-cleanup-nostart-stop-gc.c > create mode 100644 libio/tst-cleanup-start-stop-gc-static.c > create mode 100644 libio/tst-cleanup-start-stop-gc.c > create mode 100644 libio/tst-cleanup.c > create mode 100644 libio/tst-cleanup.exp > > diff --git a/config.h.in b/config.h.in > index ca1547ae67..96a08c7757 100644 > --- a/config.h.in > +++ b/config.h.in > @@ -187,6 +187,9 @@ > /* Define if gcc supports attribute ifunc. */ > #undef HAVE_GCC_IFUNC > > +/* Define if CC supports attribute retain. */ > +#undef HAVE_GNU_RETAIN > + > /* Define if the linker defines __ehdr_start. */ > #undef HAVE_EHDR_START > > diff --git a/configure b/configure > index fcf43bf7de..e64b7f8efe 100755 > --- a/configure > +++ b/configure > @@ -4105,6 +4105,31 @@ fi > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > +$as_echo_n "checking for GNU attribute retain support... " >&6; } > +if ${libc_cv_gnu_retain+:} false; then : > + $as_echo_n "(cached) " >&6 > +else > + cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gnu_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > + 2>&5 ; then > + libc_cv_gnu_retain=yes > +fi > +rm -f conftest* > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > +$as_echo "$libc_cv_gnu_retain" >&6; } > +if test $libc_cv_gnu_retain = yes; then > + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > + > +fi > +config_vars="$config_vars > +have-gnu-retain = $libc_cv_gnu_retain" > + > # Check if gcc warns about alias for function with incompatible types. > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > @@ -5871,6 +5896,40 @@ fi > $as_echo "$libc_linker_feature" >&6; } > > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > +libc_linker_feature=no > +if test x"$gnu_ld" = x"yes"; then > + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > + if test -n "$libc_linker_check"; then > + cat > conftest.c <<EOF > +int _start (void) { return 42; } > +EOF > + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > + -fPIC -shared -o conftest.so conftest.c > + 1>&5' > + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > + (eval $ac_try) 2>&5 > + ac_status=$? > + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > + test $ac_status = 0; }; } > + then > + libc_linker_feature=yes > + fi > + rm -f conftest* > + fi > +fi > +if test $libc_linker_feature = yes; then > + libc_cv_z_start_stop_gc=yes > +else > + libc_cv_z_start_stop_gc=no > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > +$as_echo "$libc_linker_feature" >&6; } > +config_vars="$config_vars > +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > + > { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > libc_linker_feature=no > diff --git a/configure.ac b/configure.ac > index fce967f2c2..cc47e56e82 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -707,6 +707,23 @@ fi > rm -f conftest*]) > AC_SUBST(libc_cv_textrel_ifunc) > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > +AC_CACHE_CHECK([for GNU attribute retain support], > + libc_cv_gnu_retain, [dnl > +cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gnu_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > + 2>&AS_MESSAGE_LOG_FD ; then > + libc_cv_gnu_retain=yes > +fi > +rm -f conftest*]) > +if test $libc_cv_gnu_retain = yes; then > + AC_DEFINE(HAVE_GNU_RETAIN) > +fi > +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > + > # Check if gcc warns about alias for function with incompatible types. > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > libc_cv_gcc_incompatible_alias, [dnl > @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > AC_SUBST(libc_cv_z_execstack) > > +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > + > LIBC_LINKER_FEATURE([--no-dynamic-linker], > [-Wl,--no-dynamic-linker], > [libc_cv_no_dynamic_linker=yes], > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > index 546fc26a7b..127ea656c2 100644 > --- a/include/libc-symbols.h > +++ b/include/libc-symbols.h > @@ -352,6 +352,12 @@ for linking") > > */ > > +#ifdef HAVE_GNU_RETAIN > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > +#else > +# define attribute_used_retain __attribute__ ((__used__)) > +#endif > + > /* Symbol set support macros. */ > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > @@ -367,12 +373,12 @@ for linking") > /* When building a shared library, make the set section writable, > because it will need to be relocated at run time anyway. */ > # define _elf_set_element(set, symbol) \ > - static const void *__elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *__elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #else > # define _elf_set_element(set, symbol) \ > - static const void *const __elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #endif > > /* Define SET as a symbol set. This may be required (it is in a.out) to > diff --git a/libio/Makefile b/libio/Makefile > index 12ce41038f..ed0ce4ee81 100644 > --- a/libio/Makefile > +++ b/libio/Makefile > @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > $(objpfx)tst-bz24228-mem.out > endif > + > +tests += tst-cleanup-default tst-cleanup-default-static > +tests-static += tst-cleanup-default-static > +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > + > +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > +endif > endif > > include ../Rules > @@ -224,6 +244,14 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +define gen-tst-cleanup > +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out > + cmp $$^ > $$@; $$(evaluate-test) > +endef > + > +$(foreach t,default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ > + $(eval $(call gen-tst-cleanup,$(t)))) > + > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ > diff --git a/libio/tst-cleanup-default-static.c b/libio/tst-cleanup-default-static.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-default-static.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-default.c b/libio/tst-cleanup-default.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-default.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-nostart-stop-gc-static.c b/libio/tst-cleanup-nostart-stop-gc-static.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-nostart-stop-gc-static.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-nostart-stop-gc.c b/libio/tst-cleanup-nostart-stop-gc.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-nostart-stop-gc.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-start-stop-gc-static.c b/libio/tst-cleanup-start-stop-gc-static.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-start-stop-gc-static.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-start-stop-gc.c b/libio/tst-cleanup-start-stop-gc.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-start-stop-gc.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > new file mode 100644 > index 0000000000..837feac164 > --- /dev/null > +++ b/libio/tst-cleanup.c > @@ -0,0 +1,34 @@ > +/* Copyright (C) 2021 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + <https://www.gnu.org/licenses/>. */ > + > +/* Test that stdout is flushed after atexit callbacks were run, even if the > + * executable is linked with --gc-sections. */ > + > +#include <stdio.h> > +#include <stdlib.h> > + > +void > +hook (void) > +{ > + puts ("hello"); > +} > + > +int > +main (void) > +{ > + atexit (hook); > +} > diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > new file mode 100644 > index 0000000000..ce01362503 > --- /dev/null > +++ b/libio/tst-cleanup.exp > @@ -0,0 +1 @@ > +hello > -- > 2.31.0.208.g409f899ff0-goog > Looks good now? I want to push next week. ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-09 22:36 ` Fāng-ruì Sòng @ 2021-04-16 3:51 ` Fāng-ruì Sòng 0 siblings, 0 replies; 40+ messages in thread From: Fāng-ruì Sòng @ 2021-04-16 3:51 UTC (permalink / raw) To: H.J. Lu; +Cc: GNU C Library, Florian Weimer On Fri, Apr 9, 2021 at 3:36 PM Fāng-ruì Sòng <maskray@google.com> wrote: > > On Tue, Apr 6, 2021 at 2:46 PM Fangrui Song <maskray@google.com> wrote: > > > > > > On 2021-04-05, H.J. Lu wrote: > > >On Mon, Apr 5, 2021 at 2:03 PM Fangrui Song <maskray@google.com> wrote: > > >> > > >> On 2021-04-05, H.J. Lu wrote: > > >> >On Mon, Apr 5, 2021 at 11:17 AM Fangrui Song <maskray@google.com> wrote: > > >> >> > > >> >> On 2021-04-04, H.J. Lu wrote: > > >> >> >On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song <maskray@google.com> wrote: > > >> >> >> > > >> >> >> On 2021-04-03, H.J. Lu wrote: > > >> >> >> >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: > > >> >> >> >> > > >> >> >> >> > > >> >> >> >> On 2021-04-02, H.J. Lu wrote: > > >> >> >> >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: > > >> >> >> >> >> > > >> >> >> >> >> On 2021-04-01, H.J. Lu wrote: > > >> >> >> >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > > >> >> >> >> >> >> > > >> >> >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined > > >> >> >> >> >> >> variables will be retained by the linker. > > >> >> >> >> >> >> > > >> >> >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > > >> >> >> >> >> >> will not be optimized out; 'retain' prevents section garbage collection > > >> >> >> >> >> >> if the linker support SHF_GNU_RETAIN. > > >> >> >> >> >> >> > > >> >> >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > > >> >> >> >> >> >> identifier name sections to be GCed even if there are live > > >> >> >> >> >> >> __start_/__stop_ references. > > >> >> >> >> >> >> > > >> >> >> >> >> >> Without the change, there are some static linking problems, e.g. > > >> >> >> >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > > >> >> >> >> >> >> stdout is not flushed on exit. > > >> >> >> >> >> >> > > >> >> >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > > >> >> >> >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > > >> >> >> >> >> >> --- > > >> >> >> >> >> >> Changes in v1 -> v2: > > >> >> >> >> >> >> * Define attribute_used_retain_section > > >> >> >> >> >> >> Changes in v2 -> v3: > > >> >> >> >> >> >> * Use attribute_used_retain instead attribute_used_retain_section > > >> >> >> >> >> >> Changes in v3 -> v4: > > >> >> >> >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > > >> >> >> >> >> >> Changes in v4 -> v5: > > >> >> >> >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > > >> >> >> >> >> >> * Rename *gcc_retain* to *gnu_retain* > > >> >> >> >> >> >> --- > > >> >> >> >> >> >> config.h.in | 3 +++ > > >> >> >> >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > > >> >> >> >> >> >> configure.ac | 21 +++++++++++++++ > > >> >> >> >> >> >> include/libc-symbols.h | 14 +++++++--- > > >> >> >> >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ > > >> >> >> >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > > >> >> >> >> >> >> libio/tst-cleanup.exp | 1 + > > >> >> >> >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) > > >> >> >> >> >> >> create mode 100644 libio/tst-cleanup.c > > >> >> >> >> >> >> create mode 100644 libio/tst-cleanup.exp > > >> >> >> >> >> >> > > >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in > > >> >> >> >> >> >> index ca1547ae67..96a08c7757 100644 > > >> >> >> >> >> >> --- a/config.h.in > > >> >> >> >> >> >> +++ b/config.h.in > > >> >> >> >> >> >> @@ -187,6 +187,9 @@ > > >> >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ > > >> >> >> >> >> >> #undef HAVE_GCC_IFUNC > > >> >> >> >> >> >> > > >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ > > >> >> >> >> >> >> +#undef HAVE_GNU_RETAIN > > >> >> >> >> >> >> + > > >> >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ > > >> >> >> >> >> >> #undef HAVE_EHDR_START > > >> >> >> >> >> >> > > >> >> >> >> >> >> diff --git a/configure b/configure > > >> >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 > > >> >> >> >> >> >> --- a/configure > > >> >> >> >> >> >> +++ b/configure > > >> >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi > > >> >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > > >> >> >> >> >> >> > > >> >> >> >> >> >> > > >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > > >> >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > > >> >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > > >> >> >> >> >> >> + $as_echo_n "(cached) " >&6 > > >> >> >> >> >> >> +else > > >> >> >> >> >> >> + cat > conftest.c <<EOF > > >> >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > >> >> >> >> >> >> +EOF > > >> >> >> >> >> >> +libc_cv_gnu_retain=no > > >> >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > > >> >> >> >> >> >> + 2>&5 ; then > > >> >> >> >> >> >> + libc_cv_gnu_retain=yes > > >> >> >> >> >> >> +fi > > >> >> >> >> >> >> +rm -f conftest* > > >> >> >> >> >> >> +fi > > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > > >> >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > > >> >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > > >> >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > > >> >> >> >> >> >> + > > >> >> >> >> >> >> +fi > > >> >> >> >> >> >> +config_vars="$config_vars > > >> >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > > >> >> >> >> >> >> + > > >> >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > > >> >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > > >> >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > > >> >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi > > >> >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } > > >> >> >> >> >> >> > > >> >> >> >> >> >> > > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > > >> >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > > >> >> >> >> >> >> +libc_linker_feature=no > > >> >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then > > >> >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > > >> >> >> >> >> >> + if test -n "$libc_linker_check"; then > > >> >> >> >> >> >> + cat > conftest.c <<EOF > > >> >> >> >> >> >> +int _start (void) { return 42; } > > >> >> >> >> >> >> +EOF > > >> >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > > >> >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > > >> >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c > > >> >> >> >> >> >> + 1>&5' > > >> >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > > >> >> >> >> >> >> + (eval $ac_try) 2>&5 > > >> >> >> >> >> >> + ac_status=$? > > >> >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > > >> >> >> >> >> >> + test $ac_status = 0; }; } > > >> >> >> >> >> >> + then > > >> >> >> >> >> >> + libc_linker_feature=yes > > >> >> >> >> >> >> + fi > > >> >> >> >> >> >> + rm -f conftest* > > >> >> >> >> >> >> + fi > > >> >> >> >> >> >> +fi > > >> >> >> >> >> >> +if test $libc_linker_feature = yes; then > > >> >> >> >> >> >> + libc_cv_z_start_stop_gc=yes > > >> >> >> >> >> >> +else > > >> >> >> >> >> >> + libc_cv_z_start_stop_gc=no > > >> >> >> >> >> >> +fi > > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > > >> >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } > > >> >> >> >> >> >> +config_vars="$config_vars > > >> >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > > >> >> >> >> >> >> + > > >> >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > > >> >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > > >> >> >> >> >> >> libc_linker_feature=no > > >> >> >> >> >> >> diff --git a/configure.ac b/configure.ac > > >> >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 > > >> >> >> >> >> >> --- a/configure.ac > > >> >> >> >> >> >> +++ b/configure.ac > > >> >> >> >> >> >> @@ -707,6 +707,23 @@ fi > > >> >> >> >> >> >> rm -f conftest*]) > > >> >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > > >> >> >> >> >> >> > > >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > > >> >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > > >> >> >> >> >> >> + libc_cv_gnu_retain, [dnl > > >> >> >> >> >> >> +cat > conftest.c <<EOF > > >> >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > >> >> >> >> >> >> +EOF > > >> >> >> >> >> >> +libc_cv_gnu_retain=no > > >> >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > > >> >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > > >> >> >> >> >> >> + libc_cv_gnu_retain=yes > > >> >> >> >> >> >> +fi > > >> >> >> >> >> >> +rm -f conftest*]) > > >> >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > > >> >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > > >> >> >> >> >> >> +fi > > >> >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > > >> >> >> >> >> >> + > > >> >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > > >> >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > > >> >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl > > >> >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > > >> >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > > >> >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) > > >> >> >> >> >> >> > > >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > > >> >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > > >> >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > > >> >> >> >> >> >> + > > >> >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > > >> >> >> >> >> >> [-Wl,--no-dynamic-linker], > > >> >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], > > >> >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > > >> >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 > > >> >> >> >> >> >> --- a/include/libc-symbols.h > > >> >> >> >> >> >> +++ b/include/libc-symbols.h > > >> >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") > > >> >> >> >> >> >> > > >> >> >> >> >> >> */ > > >> >> >> >> >> >> > > >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN > > >> >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > > >> >> >> >> >> >> +#else > > >> >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > > >> >> >> >> >> >> +#endif > > >> >> >> >> >> >> + > > >> >> >> >> >> >> /* Symbol set support macros. */ > > >> >> >> >> >> >> > > >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > > >> >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") > > >> >> >> >> >> >> /* When building a shared library, make the set section writable, > > >> >> >> >> >> >> because it will need to be relocated at run time anyway. */ > > >> >> >> >> >> >> # define _elf_set_element(set, symbol) \ > > >> >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > > >> >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > > >> >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > > >> >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > >> >> >> >> >> >> #else > > >> >> >> >> >> >> # define _elf_set_element(set, symbol) \ > > >> >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > > >> >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > > >> >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > > >> >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > >> >> >> >> >> >> #endif > > >> >> >> >> >> >> > > >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > > >> >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile > > >> >> >> >> >> >> index 12ce41038f..c9c232ebc2 100644 > > >> >> >> >> >> >> --- a/libio/Makefile > > >> >> >> >> >> >> +++ b/libio/Makefile > > >> >> >> >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > > >> >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > > >> >> >> >> >> >> $(objpfx)tst-bz24228-mem.out > > >> >> >> >> >> >> endif > > >> >> >> >> >> >> + > > >> >> >> >> >> >> +tests += tst-cleanup-default > > >> >> >> >> >> >> +tests-static += tst-cleanup-default > > >> >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > > >> >> >> >> >> > > > >> >> >> >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > > >> >> >> >> >> > > >> >> >> >> >> Added. > > >> >> >> >> >> > > >> >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > > >> >> >> >> >> >> + > > >> >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > > >> >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > > >> >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > > >> >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > > >> >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > > >> >> >> >> >> > > > >> >> >> >> >> >Same here. > > >> >> >> >> >> > > >> >> >> >> >> Added. > > >> >> >> >> >> > > >> >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > > >> >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > > >> >> >> >> >> >> +endif > > >> >> >> >> >> >> endif > > >> >> >> >> >> >> > > >> >> >> >> >> >> include ../Rules > > >> >> >> >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > > >> >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > > >> >> >> >> >> >> endif > > >> >> >> >> >> >> > > >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > > >> >> >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> >> >> + $(evaluate-test) > > >> >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > > >> >> >> >> >> >> + $(compile.c) -o $@ > > >> >> >> >> >> >> + > > >> >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > > >> >> >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> >> >> + $(evaluate-test) > > >> >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > > >> >> >> >> >> >> + $(compile.c) -o $@ > > >> >> >> >> >> >> + > > >> >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > > >> >> >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> >> >> + $(evaluate-test) > > >> >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > > >> >> >> >> >> >> + $(compile.c) -o $@ > > >> >> >> >> >> >> > > >> >> >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > > >> >> >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > > >> >> >> >> >> >> $(common-objpfx)libio/; \ > > >> >> >> >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > > >> >> >> >> >> >> new file mode 100644 > > >> >> >> >> >> >> index 0000000000..7f0a34a91e > > >> >> >> >> >> >> --- /dev/null > > >> >> >> >> >> >> +++ b/libio/tst-cleanup.c > > >> >> >> >> >> >> @@ -0,0 +1,33 @@ > > >> >> >> >> >> > > > >> >> >> >> >> >Please add a comment saying that test --gc-sections. > > >> >> >> >> >> > > >> >> >> >> >> OK, added. > > >> >> >> >> >> > > >> >> >> >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. > > >> >> >> >> >> >> + This file is part of the GNU C Library. > > >> >> >> >> >> >> + > > >> >> >> >> >> >> + The GNU C Library is free software; you can redistribute it and/or > > >> >> >> >> >> >> + modify it under the terms of the GNU Lesser General Public > > >> >> >> >> >> >> + License as published by the Free Software Foundation; either > > >> >> >> >> >> >> + version 2.1 of the License, or (at your option) any later version. > > >> >> >> >> >> >> + > > >> >> >> >> >> >> + The GNU C Library is distributed in the hope that it will be useful, > > >> >> >> >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of > > >> >> >> >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > > >> >> >> >> >> >> + Lesser General Public License for more details. > > >> >> >> >> >> >> + > > >> >> >> >> >> >> + You should have received a copy of the GNU Lesser General Public > > >> >> >> >> >> >> + License along with the GNU C Library; if not, see > > >> >> >> >> >> >> + <https://www.gnu.org/licenses/>. */ > > >> >> >> >> >> >> + > > >> >> >> >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ > > >> >> >> >> >> >> + > > >> >> >> >> >> >> +#include <stdio.h> > > >> >> >> >> >> >> +#include <stdlib.h> > > >> >> >> >> >> >> + > > >> >> >> >> >> >> +void > > >> >> >> >> >> >> +hook (void) > > >> >> >> >> >> >> +{ > > >> >> >> >> >> >> + puts ("hello"); > > >> >> >> >> >> >> +} > > >> >> >> >> >> >> + > > >> >> >> >> >> >> +int > > >> >> >> >> >> >> +main (void) > > >> >> >> >> >> >> +{ > > >> >> >> >> >> >> + atexit (hook); > > >> >> >> >> >> >> +} > > >> >> >> >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > > >> >> >> >> >> >> new file mode 100644 > > >> >> >> >> >> >> index 0000000000..ce01362503 > > >> >> >> >> >> >> --- /dev/null > > >> >> >> >> >> >> +++ b/libio/tst-cleanup.exp > > >> >> >> >> >> >> @@ -0,0 +1 @@ > > >> >> >> >> >> >> +hello > > >> >> >> >> >> >> -- > > >> >> >> >> >> >> 2.31.0.291.g576ba9dcdaf-goog > > >> >> >> >> >> >> > > >> >> >> >> >> > > > >> >> >> >> >> > > >> >> >> >> >> diff --git a/config.h.in b/config.h.in > > >> >> >> >> >> index ca1547ae67..96a08c7757 100644 > > >> >> >> >> >> --- a/config.h.in > > >> >> >> >> >> +++ b/config.h.in > > >> >> >> >> >> @@ -187,6 +187,9 @@ > > >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ > > >> >> >> >> >> #undef HAVE_GCC_IFUNC > > >> >> >> >> >> > > >> >> >> >> >> +/* Define if CC supports attribute retain. */ > > >> >> >> >> >> +#undef HAVE_GNU_RETAIN > > >> >> >> >> >> + > > >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ > > >> >> >> >> >> #undef HAVE_EHDR_START > > >> >> >> >> >> > > >> >> >> >> >> diff --git a/configure b/configure > > >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 > > >> >> >> >> >> --- a/configure > > >> >> >> >> >> +++ b/configure > > >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi > > >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > > >> >> >> >> >> > > >> >> >> >> >> > > >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > > >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > > >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > > >> >> >> >> >> + $as_echo_n "(cached) " >&6 > > >> >> >> >> >> +else > > >> >> >> >> >> + cat > conftest.c <<EOF > > >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > >> >> >> >> >> +EOF > > >> >> >> >> >> +libc_cv_gnu_retain=no > > >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > > >> >> >> >> >> + 2>&5 ; then > > >> >> >> >> >> + libc_cv_gnu_retain=yes > > >> >> >> >> >> +fi > > >> >> >> >> >> +rm -f conftest* > > >> >> >> >> >> +fi > > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > > >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > > >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > > >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > > >> >> >> >> >> + > > >> >> >> >> >> +fi > > >> >> >> >> >> +config_vars="$config_vars > > >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > > >> >> >> >> >> + > > >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > > >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > > >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > > >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi > > >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } > > >> >> >> >> >> > > >> >> >> >> >> > > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > > >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > > >> >> >> >> >> +libc_linker_feature=no > > >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then > > >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > > >> >> >> >> >> + if test -n "$libc_linker_check"; then > > >> >> >> >> >> + cat > conftest.c <<EOF > > >> >> >> >> >> +int _start (void) { return 42; } > > >> >> >> >> >> +EOF > > >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > > >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > > >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c > > >> >> >> >> >> + 1>&5' > > >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > > >> >> >> >> >> + (eval $ac_try) 2>&5 > > >> >> >> >> >> + ac_status=$? > > >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > > >> >> >> >> >> + test $ac_status = 0; }; } > > >> >> >> >> >> + then > > >> >> >> >> >> + libc_linker_feature=yes > > >> >> >> >> >> + fi > > >> >> >> >> >> + rm -f conftest* > > >> >> >> >> >> + fi > > >> >> >> >> >> +fi > > >> >> >> >> >> +if test $libc_linker_feature = yes; then > > >> >> >> >> >> + libc_cv_z_start_stop_gc=yes > > >> >> >> >> >> +else > > >> >> >> >> >> + libc_cv_z_start_stop_gc=no > > >> >> >> >> >> +fi > > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > > >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } > > >> >> >> >> >> +config_vars="$config_vars > > >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > > >> >> >> >> >> + > > >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > > >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > > >> >> >> >> >> libc_linker_feature=no > > >> >> >> >> >> diff --git a/configure.ac b/configure.ac > > >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 > > >> >> >> >> >> --- a/configure.ac > > >> >> >> >> >> +++ b/configure.ac > > >> >> >> >> >> @@ -707,6 +707,23 @@ fi > > >> >> >> >> >> rm -f conftest*]) > > >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > > >> >> >> >> >> > > >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > > >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > > >> >> >> >> >> + libc_cv_gnu_retain, [dnl > > >> >> >> >> >> +cat > conftest.c <<EOF > > >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > >> >> >> >> >> +EOF > > >> >> >> >> >> +libc_cv_gnu_retain=no > > >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > > >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > > >> >> >> >> >> + libc_cv_gnu_retain=yes > > >> >> >> >> >> +fi > > >> >> >> >> >> +rm -f conftest*]) > > >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > > >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > > >> >> >> >> >> +fi > > >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > > >> >> >> >> >> + > > >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > > >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > > >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl > > >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > > >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > > >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) > > >> >> >> >> >> > > >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > > >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > > >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > > >> >> >> >> >> + > > >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > > >> >> >> >> >> [-Wl,--no-dynamic-linker], > > >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], > > >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > > >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 > > >> >> >> >> >> --- a/include/libc-symbols.h > > >> >> >> >> >> +++ b/include/libc-symbols.h > > >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") > > >> >> >> >> >> > > >> >> >> >> >> */ > > >> >> >> >> >> > > >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN > > >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > > >> >> >> >> >> +#else > > >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > > >> >> >> >> >> +#endif > > >> >> >> >> >> + > > >> >> >> >> >> /* Symbol set support macros. */ > > >> >> >> >> >> > > >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > > >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") > > >> >> >> >> >> /* When building a shared library, make the set section writable, > > >> >> >> >> >> because it will need to be relocated at run time anyway. */ > > >> >> >> >> >> # define _elf_set_element(set, symbol) \ > > >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > > >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > > >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > > >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > >> >> >> >> >> #else > > >> >> >> >> >> # define _elf_set_element(set, symbol) \ > > >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > > >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > > >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > > >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > >> >> >> >> >> #endif > > >> >> >> >> >> > > >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > > >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile > > >> >> >> >> >> index 12ce41038f..ad0d53bb49 100644 > > >> >> >> >> >> --- a/libio/Makefile > > >> >> >> >> >> +++ b/libio/Makefile > > >> >> >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > > >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > > >> >> >> >> >> $(objpfx)tst-bz24228-mem.out > > >> >> >> >> >> endif > > >> >> >> >> >> + > > >> >> >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static > > >> >> >> >> >> +tests-static += tst-cleanup-default-static > > >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > > >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > > >> >> >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > > >> >> >> >> >> + > > >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > > >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > > >> >> >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > > >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > > >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > > >> >> >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > > >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > > >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > > >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > > >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > > >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > > >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > > >> >> >> >> >> +endif > > >> >> >> >> >> endif > > >> >> >> >> >> > > >> >> >> >> >> include ../Rules > > >> >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > > >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > > >> >> >> >> >> endif > > >> >> >> >> >> > > >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > > >> >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> >> + $(evaluate-test) > > >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > > >> >> >> >> >> + $(compile.c) -o $@ > > >> >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > > >> >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> >> + $(evaluate-test) > > >> >> >> >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c > > >> >> >> >> >> + $(compile.c) -o $@ > > >> >> >> >> >> + > > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > > >> >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> >> + $(evaluate-test) > > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > > >> >> >> >> >> + $(compile.c) -o $@ > > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > > >> >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> >> + $(evaluate-test) > > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > > >> >> >> >> >> + $(compile.c) -o $@ > > >> >> >> >> > > > >> >> >> >> >Please add a separate .c file for each test to get the correct dependency. > > >> >> >> >> > > >> >> >> >> Changed this block to: > > >> >> >> >> > > >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > > >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > > >> >> >> >> endif > > >> >> >> >> > > >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > > >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> + $(evaluate-test) > > >> >> >> >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c > > >> >> >> >> + cp $< $@ > > >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > > >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> + $(evaluate-test) > > >> >> >> >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c > > >> >> >> >> + cp $< $@ > > >> >> >> >> + > > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > > >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> + $(evaluate-test) > > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > > >> >> >> >> + $(compile.c) -o $@ > > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > > >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> + $(evaluate-test) > > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c > > >> >> >> >> + cp $< $@ > > >> >> >> >> + > > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > > >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> + $(evaluate-test) > > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c > > >> >> >> >> + cp $< $@ > > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out > > >> >> >> >> + cmp $^ > $@; \ > > >> >> >> >> + $(evaluate-test) > > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c > > >> >> >> >> + cp $< $@ > > >> >> >> >> + > > >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > > >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > > >> >> >> >> $(common-objpfx)libio/; \ > > >> >> >> >> > > >> >> >> > > > >> >> >> >"make clean" doesn't remove the generated files. The standard way in glibc > > >> >> >> >is to add a *-static.c source. > > >> >> >> > > >> >> >> I'll use .INTERMEDIATE and $(eval $(call ..)) > > >> >> >> > > >> >> >> diff --git a/libio/Makefile b/libio/Makefile > > >> >> >> index 12ce41038f..a9b44f04df 100644 > > >> >> >> --- a/libio/Makefile > > >> >> >> +++ b/libio/Makefile > > >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > > >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > > >> >> >> $(objpfx)tst-bz24228-mem.out > > >> >> >> endif > > >> >> >> + > > >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static > > >> >> >> +tests-static += tst-cleanup-default-static > > >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > > >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > > >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > > >> >> >> + > > >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > > >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > > >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > > >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > > >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > > >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > > >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > > >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > > >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > > >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > > >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > > >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > > >> >> >> +endif > > >> >> >> endif > > >> >> >> > > >> >> >> include ../Rules > > >> >> >> @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > > >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > > >> >> >> endif > > >> >> >> > > >> >> >> +define gen-tst-cleanup > > >> >> >> +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out > > >> >> >> + cmp $$^ > $$@; $$(evaluate-test) > > >> >> >> +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c > > >> >> >> + cp $$< $$@ > > >> >> >> +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c > > >> >> >> +endef > > >> >> >> + > > >> >> >> +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ > > >> >> >> + $(eval $(call gen-tst-cleanup,$(t)))) > > >> >> >> + > > >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > > >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > > >> >> >> $(common-objpfx)libio/; \ > > >> >> > > > >> >> >There are 2 issues with static tests: > > >> >> > > > >> >> >1. A separate static source is needed. > > >> >> > > >> >> .INTERMEDIATE perfectly solves the lingering copied source issue. > > >> >> I don't see lingering libio/tst-cleanup-*.c > > >> > > > >> >I was referring to > > >> > > > >> >elf/tst-array1-static.c > > >> >elf/tst-array5-static.c > > >> >elf/tst-dl-iter-static.c > > >> >elf/tst-dst-static.c > > >> >elf/tst-leaks1-static.c > > >> >elf/tst-libc_dlvsym-static.c > > >> >elf/tst-linkall-static.c > > >> >elf/tst-ptrguard1-static.c > > >> >elf/tst-single_threaded-pthread-static.c > > >> >elf/tst-single_threaded-static.c > > >> >elf/tst-stackguard1-static.c > > >> >elf/tst-tls1-static.c > > >> >elf/tst-tls2-static.c > > >> >elf/tst-tls9-static.c > > >> >elf/tst-tlsalign-extern-static.c > > >> >elf/tst-tlsalign-static.c > > >> >gmon/tst-gmon-static.c > > >> >gmon/tst-profile-static.c > > >> >localedata/bug-setlocale1-static.c > > >> >localedata/tst-langinfo-newlocale-static.c > > >> >localedata/tst-langinfo-setlocale-static.c > > >> >localedata/tst-langinfo-static.c > > >> >malloc/tst-malloc-usable-static.c > > >> >math/test-fpucw-ieee-static.c > > >> >math/test-fpucw-static.c > > >> >math/test-signgam-uchar-init-static.c > > >> >math/test-signgam-uchar-static.c > > >> >math/test-signgam-uint-init-static.c > > >> >math/test-signgam-uint-static.c > > >> >math/test-signgam-ullong-init-static.c > > >> >math/test-signgam-ullong-static.c > > >> >nptl/tst-mutex8-static.c > > >> >nptl/tst-mutexpi8-static.c > > >> >nptl/tst-sem11-static.c > > >> >nptl/tst-sem12-static.c > > >> >nptl/tst-setuid1-static.c > > >> >nptl/tst-stackguard1-static.c > > >> >nss/tst-nss-static.c > > >> >posix/tst-exec-static.c > > >> >posix/tst-spawn-static.c > > >> >setjmp/tst-setjmp-static.c > > >> > > > >> >> >2. We need to add the static test to both tests and tests-static. > > >> >> > > >> >> tests-static suffices. I have checked some tests-static usage in other > > >> >> directories. > > >> > > > >> >There are > > >> > > > >> >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > > >> > tst-sigsetjmp tst-setjmp-static > > >> >tests-static := tst-setjmp-static > > >> > > > >> >They should be replaced by something like > > >> > > > >> >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > > >> > tst-sigsetjmp > > >> >tests-static-add := tst-setjmp-static > > >> > > >> Re-checking, the tst-cleanup* targets are in tests-special so `make tests` will build them. > > >> If a tests-static target is not in tests-internal/tests-special, looks like it needs to be in tests. > > >> > > >> As is, I think my usage is correct. > > >> > > > > > >The current glibc convention is to use > > > > > >[hjl@gnu-cfl-2 x86-glibc]$ cat elf/tst-tls9-static.c > > >#include "tst-tls9.c" > > >[hjl@gnu-cfl-2 x86-glibc]$ > > > > > >to test both dynamic and static libc. If we want to use a single > > >source, we should create > > >a framework to cover all such tests. > > > > OK. Dropped cp $< $@ and .INTERMEDIATE > > > > > > From e937ae26a4a9a8ff6b1198f347f0b141a9285305 Mon Sep 17 00:00:00 2001 > > From: Fangrui Song <maskray@google.com> > > Date: Tue, 6 Apr 2021 14:45:01 -0700 > > Subject: [PATCH] Set the retain attribute on _elf_set_element if CC supports > > [BZ #27492] > > MIME-Version: 1.0 > > Content-Type: text/plain; charset=UTF-8 > > Content-Transfer-Encoding: 8bit > > > > So that text_set_element/data_set_element/bss_set_element defined > > variables will be retained by the linker. > > > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > > will not be optimized out; 'retain' prevents section garbage collection > > if the linker support SHF_GNU_RETAIN. > > > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > > identifier name sections to be GCed even if there are live > > __start_/__stop_ references. > > > > Without the change, there are some static linking problems, e.g. > > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > > stdout is not flushed on exit. > > > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > > --- > > config.h.in | 3 ++ > > configure | 59 ++++++++++++++++++++++ > > configure.ac | 21 ++++++++ > > include/libc-symbols.h | 14 +++-- > > libio/Makefile | 28 ++++++++++ > > libio/tst-cleanup-default-static.c | 1 + > > libio/tst-cleanup-default.c | 1 + > > libio/tst-cleanup-nostart-stop-gc-static.c | 1 + > > libio/tst-cleanup-nostart-stop-gc.c | 1 + > > libio/tst-cleanup-start-stop-gc-static.c | 1 + > > libio/tst-cleanup-start-stop-gc.c | 1 + > > libio/tst-cleanup.c | 34 +++++++++++++ > > libio/tst-cleanup.exp | 1 + > > 13 files changed, 162 insertions(+), 4 deletions(-) > > create mode 100644 libio/tst-cleanup-default-static.c > > create mode 100644 libio/tst-cleanup-default.c > > create mode 100644 libio/tst-cleanup-nostart-stop-gc-static.c > > create mode 100644 libio/tst-cleanup-nostart-stop-gc.c > > create mode 100644 libio/tst-cleanup-start-stop-gc-static.c > > create mode 100644 libio/tst-cleanup-start-stop-gc.c > > create mode 100644 libio/tst-cleanup.c > > create mode 100644 libio/tst-cleanup.exp > > > > diff --git a/config.h.in b/config.h.in > > index ca1547ae67..96a08c7757 100644 > > --- a/config.h.in > > +++ b/config.h.in > > @@ -187,6 +187,9 @@ > > /* Define if gcc supports attribute ifunc. */ > > #undef HAVE_GCC_IFUNC > > > > +/* Define if CC supports attribute retain. */ > > +#undef HAVE_GNU_RETAIN > > + > > /* Define if the linker defines __ehdr_start. */ > > #undef HAVE_EHDR_START > > > > diff --git a/configure b/configure > > index fcf43bf7de..e64b7f8efe 100755 > > --- a/configure > > +++ b/configure > > @@ -4105,6 +4105,31 @@ fi > > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > > > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > > +$as_echo_n "checking for GNU attribute retain support... " >&6; } > > +if ${libc_cv_gnu_retain+:} false; then : > > + $as_echo_n "(cached) " >&6 > > +else > > + cat > conftest.c <<EOF > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > +EOF > > +libc_cv_gnu_retain=no > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > > + 2>&5 ; then > > + libc_cv_gnu_retain=yes > > +fi > > +rm -f conftest* > > +fi > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > > +$as_echo "$libc_cv_gnu_retain" >&6; } > > +if test $libc_cv_gnu_retain = yes; then > > + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > > + > > +fi > > +config_vars="$config_vars > > +have-gnu-retain = $libc_cv_gnu_retain" > > + > > # Check if gcc warns about alias for function with incompatible types. > > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > > @@ -5871,6 +5896,40 @@ fi > > $as_echo "$libc_linker_feature" >&6; } > > > > > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > > +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > > +libc_linker_feature=no > > +if test x"$gnu_ld" = x"yes"; then > > + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > > + if test -n "$libc_linker_check"; then > > + cat > conftest.c <<EOF > > +int _start (void) { return 42; } > > +EOF > > + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > > + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > > + -fPIC -shared -o conftest.so conftest.c > > + 1>&5' > > + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > > + (eval $ac_try) 2>&5 > > + ac_status=$? > > + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > > + test $ac_status = 0; }; } > > + then > > + libc_linker_feature=yes > > + fi > > + rm -f conftest* > > + fi > > +fi > > +if test $libc_linker_feature = yes; then > > + libc_cv_z_start_stop_gc=yes > > +else > > + libc_cv_z_start_stop_gc=no > > +fi > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > > +$as_echo "$libc_linker_feature" >&6; } > > +config_vars="$config_vars > > +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > > + > > { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > > $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > > libc_linker_feature=no > > diff --git a/configure.ac b/configure.ac > > index fce967f2c2..cc47e56e82 100644 > > --- a/configure.ac > > +++ b/configure.ac > > @@ -707,6 +707,23 @@ fi > > rm -f conftest*]) > > AC_SUBST(libc_cv_textrel_ifunc) > > > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > > +AC_CACHE_CHECK([for GNU attribute retain support], > > + libc_cv_gnu_retain, [dnl > > +cat > conftest.c <<EOF > > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > > +EOF > > +libc_cv_gnu_retain=no > > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > > + 2>&AS_MESSAGE_LOG_FD ; then > > + libc_cv_gnu_retain=yes > > +fi > > +rm -f conftest*]) > > +if test $libc_cv_gnu_retain = yes; then > > + AC_DEFINE(HAVE_GNU_RETAIN) > > +fi > > +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > > + > > # Check if gcc warns about alias for function with incompatible types. > > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > > libc_cv_gcc_incompatible_alias, [dnl > > @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > > [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > > AC_SUBST(libc_cv_z_execstack) > > > > +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > > + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > > +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > > + > > LIBC_LINKER_FEATURE([--no-dynamic-linker], > > [-Wl,--no-dynamic-linker], > > [libc_cv_no_dynamic_linker=yes], > > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > > index 546fc26a7b..127ea656c2 100644 > > --- a/include/libc-symbols.h > > +++ b/include/libc-symbols.h > > @@ -352,6 +352,12 @@ for linking") > > > > */ > > > > +#ifdef HAVE_GNU_RETAIN > > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > > +#else > > +# define attribute_used_retain __attribute__ ((__used__)) > > +#endif > > + > > /* Symbol set support macros. */ > > > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > > @@ -367,12 +373,12 @@ for linking") > > /* When building a shared library, make the set section writable, > > because it will need to be relocated at run time anyway. */ > > # define _elf_set_element(set, symbol) \ > > - static const void *__elf_set_##set##_element_##symbol##__ \ > > - __attribute__ ((used, section (#set))) = &(symbol) > > + static const void *__elf_set_##set##_element_##symbol##__ \ > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > #else > > # define _elf_set_element(set, symbol) \ > > - static const void *const __elf_set_##set##_element_##symbol##__ \ > > - __attribute__ ((used, section (#set))) = &(symbol) > > + static const void *const __elf_set_##set##_element_##symbol##__ \ > > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > > #endif > > > > /* Define SET as a symbol set. This may be required (it is in a.out) to > > diff --git a/libio/Makefile b/libio/Makefile > > index 12ce41038f..ed0ce4ee81 100644 > > --- a/libio/Makefile > > +++ b/libio/Makefile > > @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > > $(objpfx)tst-bz24228-mem.out > > endif > > + > > +tests += tst-cleanup-default tst-cleanup-default-static > > +tests-static += tst-cleanup-default-static > > +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > > +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > > +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > > + > > +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > > +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > > + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > > +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > > +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > > + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > > + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > > + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > > +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > > +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > > +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > > +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > > +endif > > endif > > > > include ../Rules > > @@ -224,6 +244,14 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > > $(objpfx)tst-wfile-sync.out: $(gen-locales) > > endif > > > > +define gen-tst-cleanup > > +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out > > + cmp $$^ > $$@; $$(evaluate-test) > > +endef > > + > > +$(foreach t,default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ > > + $(eval $(call gen-tst-cleanup,$(t)))) > > + > > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > > $(common-objpfx)libio/; \ > > diff --git a/libio/tst-cleanup-default-static.c b/libio/tst-cleanup-default-static.c > > new file mode 100644 > > index 0000000000..c39956e2a8 > > --- /dev/null > > +++ b/libio/tst-cleanup-default-static.c > > @@ -0,0 +1 @@ > > +#include "tst-cleanup.c" > > diff --git a/libio/tst-cleanup-default.c b/libio/tst-cleanup-default.c > > new file mode 100644 > > index 0000000000..c39956e2a8 > > --- /dev/null > > +++ b/libio/tst-cleanup-default.c > > @@ -0,0 +1 @@ > > +#include "tst-cleanup.c" > > diff --git a/libio/tst-cleanup-nostart-stop-gc-static.c b/libio/tst-cleanup-nostart-stop-gc-static.c > > new file mode 100644 > > index 0000000000..c39956e2a8 > > --- /dev/null > > +++ b/libio/tst-cleanup-nostart-stop-gc-static.c > > @@ -0,0 +1 @@ > > +#include "tst-cleanup.c" > > diff --git a/libio/tst-cleanup-nostart-stop-gc.c b/libio/tst-cleanup-nostart-stop-gc.c > > new file mode 100644 > > index 0000000000..c39956e2a8 > > --- /dev/null > > +++ b/libio/tst-cleanup-nostart-stop-gc.c > > @@ -0,0 +1 @@ > > +#include "tst-cleanup.c" > > diff --git a/libio/tst-cleanup-start-stop-gc-static.c b/libio/tst-cleanup-start-stop-gc-static.c > > new file mode 100644 > > index 0000000000..c39956e2a8 > > --- /dev/null > > +++ b/libio/tst-cleanup-start-stop-gc-static.c > > @@ -0,0 +1 @@ > > +#include "tst-cleanup.c" > > diff --git a/libio/tst-cleanup-start-stop-gc.c b/libio/tst-cleanup-start-stop-gc.c > > new file mode 100644 > > index 0000000000..c39956e2a8 > > --- /dev/null > > +++ b/libio/tst-cleanup-start-stop-gc.c > > @@ -0,0 +1 @@ > > +#include "tst-cleanup.c" > > diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > > new file mode 100644 > > index 0000000000..837feac164 > > --- /dev/null > > +++ b/libio/tst-cleanup.c > > @@ -0,0 +1,34 @@ > > +/* Copyright (C) 2021 Free Software Foundation, Inc. > > + This file is part of the GNU C Library. > > + > > + The GNU C Library is free software; you can redistribute it and/or > > + modify it under the terms of the GNU Lesser General Public > > + License as published by the Free Software Foundation; either > > + version 2.1 of the License, or (at your option) any later version. > > + > > + The GNU C Library is distributed in the hope that it will be useful, > > + but WITHOUT ANY WARRANTY; without even the implied warranty of > > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > > + Lesser General Public License for more details. > > + > > + You should have received a copy of the GNU Lesser General Public > > + License along with the GNU C Library; if not, see > > + <https://www.gnu.org/licenses/>. */ > > + > > +/* Test that stdout is flushed after atexit callbacks were run, even if the > > + * executable is linked with --gc-sections. */ > > + > > +#include <stdio.h> > > +#include <stdlib.h> > > + > > +void > > +hook (void) > > +{ > > + puts ("hello"); > > +} > > + > > +int > > +main (void) > > +{ > > + atexit (hook); > > +} > > diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > > new file mode 100644 > > index 0000000000..ce01362503 > > --- /dev/null > > +++ b/libio/tst-cleanup.exp > > @@ -0,0 +1 @@ > > +hello > > -- > > 2.31.0.208.g409f899ff0-goog > > > > Looks good now? I want to push next week. Ping... ^ permalink raw reply [flat|nested] 40+ messages in thread
* Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] 2021-04-06 21:46 ` Fangrui Song 2021-04-09 22:36 ` Fāng-ruì Sòng @ 2021-04-16 13:00 ` H.J. Lu 1 sibling, 0 replies; 40+ messages in thread From: H.J. Lu @ 2021-04-16 13:00 UTC (permalink / raw) To: Fangrui Song; +Cc: GNU C Library, Florian Weimer On Tue, Apr 6, 2021 at 2:46 PM Fangrui Song <maskray@google.com> wrote: > > > On 2021-04-05, H.J. Lu wrote: > >On Mon, Apr 5, 2021 at 2:03 PM Fangrui Song <maskray@google.com> wrote: > >> > >> On 2021-04-05, H.J. Lu wrote: > >> >On Mon, Apr 5, 2021 at 11:17 AM Fangrui Song <maskray@google.com> wrote: > >> >> > >> >> On 2021-04-04, H.J. Lu wrote: > >> >> >On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> > >> >> >> On 2021-04-03, H.J. Lu wrote: > >> >> >> >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song <maskray@google.com> wrote: > >> >> >> >> > >> >> >> >> > >> >> >> >> On 2021-04-02, H.J. Lu wrote: > >> >> >> >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> >> >> > >> >> >> >> >> On 2021-04-01, H.J. Lu wrote: > >> >> >> >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song <maskray@google.com> wrote: > >> >> >> >> >> >> > >> >> >> >> >> >> So that text_set_element/data_set_element/bss_set_element defined > >> >> >> >> >> >> variables will be retained by the linker. > >> >> >> >> >> >> > >> >> >> >> >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> >> >> >> >> >> will not be optimized out; 'retain' prevents section garbage collection > >> >> >> >> >> >> if the linker support SHF_GNU_RETAIN. > >> >> >> >> >> >> > >> >> >> >> >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> >> >> >> >> >> identifier name sections to be GCed even if there are live > >> >> >> >> >> >> __start_/__stop_ references. > >> >> >> >> >> >> > >> >> >> >> >> >> Without the change, there are some static linking problems, e.g. > >> >> >> >> >> >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> >> >> >> >> >> stdout is not flushed on exit. > >> >> >> >> >> >> > >> >> >> >> >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> >> >> >> >> >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> >> >> >> >> >> --- > >> >> >> >> >> >> Changes in v1 -> v2: > >> >> >> >> >> >> * Define attribute_used_retain_section > >> >> >> >> >> >> Changes in v2 -> v3: > >> >> >> >> >> >> * Use attribute_used_retain instead attribute_used_retain_section > >> >> >> >> >> >> Changes in v3 -> v4: > >> >> >> >> >> >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> >> >> >> >> >> Changes in v4 -> v5: > >> >> >> >> >> >> * Enable -z start-stop-gc tests if both retain and -z start-stop-gc are supported > >> >> >> >> >> >> * Rename *gcc_retain* to *gnu_retain* > >> >> >> >> >> >> --- > >> >> >> >> >> >> config.h.in | 3 +++ > >> >> >> >> >> >> configure | 59 ++++++++++++++++++++++++++++++++++++++++++ > >> >> >> >> >> >> configure.ac | 21 +++++++++++++++ > >> >> >> >> >> >> include/libc-symbols.h | 14 +++++++--- > >> >> >> >> >> >> libio/Makefile | 32 +++++++++++++++++++++++ > >> >> >> >> >> >> libio/tst-cleanup.c | 33 +++++++++++++++++++++++ > >> >> >> >> >> >> libio/tst-cleanup.exp | 1 + > >> >> >> >> >> >> 7 files changed, 159 insertions(+), 4 deletions(-) > >> >> >> >> >> >> create mode 100644 libio/tst-cleanup.c > >> >> >> >> >> >> create mode 100644 libio/tst-cleanup.exp > >> >> >> >> >> >> > >> >> >> >> >> >> diff --git a/config.h.in b/config.h.in > >> >> >> >> >> >> index ca1547ae67..96a08c7757 100644 > >> >> >> >> >> >> --- a/config.h.in > >> >> >> >> >> >> +++ b/config.h.in > >> >> >> >> >> >> @@ -187,6 +187,9 @@ > >> >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ > >> >> >> >> >> >> #undef HAVE_GCC_IFUNC > >> >> >> >> >> >> > >> >> >> >> >> >> +/* Define if CC supports attribute retain. */ > >> >> >> >> >> >> +#undef HAVE_GNU_RETAIN > >> >> >> >> >> >> + > >> >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ > >> >> >> >> >> >> #undef HAVE_EHDR_START > >> >> >> >> >> >> > >> >> >> >> >> >> diff --git a/configure b/configure > >> >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> >> >> >> >> --- a/configure > >> >> >> >> >> >> +++ b/configure > >> >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi > >> >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> >> >> >> >> > >> >> >> >> >> >> > >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> >> >> >> >> + $as_echo_n "(cached) " >&6 > >> >> >> >> >> >> +else > >> >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> >> +EOF > >> >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> >> >> >> >> + 2>&5 ; then > >> >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +rm -f conftest* > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> >> >> >> >> + > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> >> >> >> >> + > >> >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi > >> >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> >> > >> >> >> >> >> >> > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> >> >> >> >> +libc_linker_feature=no > >> >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> >> >> >> >> + if test -n "$libc_linker_check"; then > >> >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> >> +int _start (void) { return 42; } > >> >> >> >> >> >> +EOF > >> >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> >> >> >> >> + 1>&5' > >> >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> >> >> >> >> + (eval $ac_try) 2>&5 > >> >> >> >> >> >> + ac_status=$? > >> >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> >> >> >> >> + test $ac_status = 0; }; } > >> >> >> >> >> >> + then > >> >> >> >> >> >> + libc_linker_feature=yes > >> >> >> >> >> >> + fi > >> >> >> >> >> >> + rm -f conftest* > >> >> >> >> >> >> + fi > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +if test $libc_linker_feature = yes; then > >> >> >> >> >> >> + libc_cv_z_start_stop_gc=yes > >> >> >> >> >> >> +else > >> >> >> >> >> >> + libc_cv_z_start_stop_gc=no > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> >> >> >> >> + > >> >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> >> >> >> >> libc_linker_feature=no > >> >> >> >> >> >> diff --git a/configure.ac b/configure.ac > >> >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 > >> >> >> >> >> >> --- a/configure.ac > >> >> >> >> >> >> +++ b/configure.ac > >> >> >> >> >> >> @@ -707,6 +707,23 @@ fi > >> >> >> >> >> >> rm -f conftest*]) > >> >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> >> >> >> >> > >> >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> >> >> >> >> + libc_cv_gnu_retain, [dnl > >> >> >> >> >> >> +cat > conftest.c <<EOF > >> >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> >> +EOF > >> >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +rm -f conftest*]) > >> >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> >> >> >> >> +fi > >> >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> >> >> >> >> + > >> >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) > >> >> >> >> >> >> > >> >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> >> >> >> >> + > >> >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> >> >> >> >> [-Wl,--no-dynamic-linker], > >> >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], > >> >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 > >> >> >> >> >> >> --- a/include/libc-symbols.h > >> >> >> >> >> >> +++ b/include/libc-symbols.h > >> >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") > >> >> >> >> >> >> > >> >> >> >> >> >> */ > >> >> >> >> >> >> > >> >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN > >> >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> >> >> >> >> +#else > >> >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> >> >> >> >> +#endif > >> >> >> >> >> >> + > >> >> >> >> >> >> /* Symbol set support macros. */ > >> >> >> >> >> >> > >> >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") > >> >> >> >> >> >> /* When building a shared library, make the set section writable, > >> >> >> >> >> >> because it will need to be relocated at run time anyway. */ > >> >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> >> #else > >> >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> >> #endif > >> >> >> >> >> >> > >> >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> >> >> >> index 12ce41038f..c9c232ebc2 100644 > >> >> >> >> >> >> --- a/libio/Makefile > >> >> >> >> >> >> +++ b/libio/Makefile > >> >> >> >> >> >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> >> >> >> endif > >> >> >> >> >> >> + > >> >> >> >> >> >> +tests += tst-cleanup-default > >> >> >> >> >> >> +tests-static += tst-cleanup-default > >> >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >> >> >> >> >> > > >> >> >> >> >> >Please make 2 tests, tst-cleanup-default and tst-cleanup-default-static. > >> >> >> >> >> > >> >> >> >> >> Added. > >> >> >> >> >> > >> >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> >> >> >> + > >> >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >> >> >> >> >> > > >> >> >> >> >> >Same here. > >> >> >> >> >> > >> >> >> >> >> Added. > >> >> >> >> >> > >> >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> >> >> +endif > >> >> >> >> >> >> endif > >> >> >> >> >> >> > >> >> >> >> >> >> include ../Rules > >> >> >> >> >> >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> >> >> >> endif > >> >> >> >> >> >> > >> >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> >> + > >> >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> >> + > >> >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > >> >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> >> > >> >> >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> >> >> >> $(common-objpfx)libio/; \ > >> >> >> >> >> >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > >> >> >> >> >> >> new file mode 100644 > >> >> >> >> >> >> index 0000000000..7f0a34a91e > >> >> >> >> >> >> --- /dev/null > >> >> >> >> >> >> +++ b/libio/tst-cleanup.c > >> >> >> >> >> >> @@ -0,0 +1,33 @@ > >> >> >> >> >> > > >> >> >> >> >> >Please add a comment saying that test --gc-sections. > >> >> >> >> >> > >> >> >> >> >> OK, added. > >> >> >> >> >> > >> >> >> >> >> >> +/* Copyright (C) 2021 Free Software Foundation, Inc. > >> >> >> >> >> >> + This file is part of the GNU C Library. > >> >> >> >> >> >> + > >> >> >> >> >> >> + The GNU C Library is free software; you can redistribute it and/or > >> >> >> >> >> >> + modify it under the terms of the GNU Lesser General Public > >> >> >> >> >> >> + License as published by the Free Software Foundation; either > >> >> >> >> >> >> + version 2.1 of the License, or (at your option) any later version. > >> >> >> >> >> >> + > >> >> >> >> >> >> + The GNU C Library is distributed in the hope that it will be useful, > >> >> >> >> >> >> + but WITHOUT ANY WARRANTY; without even the implied warranty of > >> >> >> >> >> >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > >> >> >> >> >> >> + Lesser General Public License for more details. > >> >> >> >> >> >> + > >> >> >> >> >> >> + You should have received a copy of the GNU Lesser General Public > >> >> >> >> >> >> + License along with the GNU C Library; if not, see > >> >> >> >> >> >> + <https://www.gnu.org/licenses/>. */ > >> >> >> >> >> >> + > >> >> >> >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ > >> >> >> >> >> >> + > >> >> >> >> >> >> +#include <stdio.h> > >> >> >> >> >> >> +#include <stdlib.h> > >> >> >> >> >> >> + > >> >> >> >> >> >> +void > >> >> >> >> >> >> +hook (void) > >> >> >> >> >> >> +{ > >> >> >> >> >> >> + puts ("hello"); > >> >> >> >> >> >> +} > >> >> >> >> >> >> + > >> >> >> >> >> >> +int > >> >> >> >> >> >> +main (void) > >> >> >> >> >> >> +{ > >> >> >> >> >> >> + atexit (hook); > >> >> >> >> >> >> +} > >> >> >> >> >> >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > >> >> >> >> >> >> new file mode 100644 > >> >> >> >> >> >> index 0000000000..ce01362503 > >> >> >> >> >> >> --- /dev/null > >> >> >> >> >> >> +++ b/libio/tst-cleanup.exp > >> >> >> >> >> >> @@ -0,0 +1 @@ > >> >> >> >> >> >> +hello > >> >> >> >> >> >> -- > >> >> >> >> >> >> 2.31.0.291.g576ba9dcdaf-goog > >> >> >> >> >> >> > >> >> >> >> >> > > >> >> >> >> >> > >> >> >> >> >> diff --git a/config.h.in b/config.h.in > >> >> >> >> >> index ca1547ae67..96a08c7757 100644 > >> >> >> >> >> --- a/config.h.in > >> >> >> >> >> +++ b/config.h.in > >> >> >> >> >> @@ -187,6 +187,9 @@ > >> >> >> >> >> /* Define if gcc supports attribute ifunc. */ > >> >> >> >> >> #undef HAVE_GCC_IFUNC > >> >> >> >> >> > >> >> >> >> >> +/* Define if CC supports attribute retain. */ > >> >> >> >> >> +#undef HAVE_GNU_RETAIN > >> >> >> >> >> + > >> >> >> >> >> /* Define if the linker defines __ehdr_start. */ > >> >> >> >> >> #undef HAVE_EHDR_START > >> >> >> >> >> > >> >> >> >> >> diff --git a/configure b/configure > >> >> >> >> >> index fcf43bf7de..e64b7f8efe 100755 > >> >> >> >> >> --- a/configure > >> >> >> >> >> +++ b/configure > >> >> >> >> >> @@ -4105,6 +4105,31 @@ fi > >> >> >> >> >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> >> >> >> >> > >> >> >> >> >> > >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > >> >> >> >> >> +$as_echo_n "checking for GNU attribute retain support... " >&6; } > >> >> >> >> >> +if ${libc_cv_gnu_retain+:} false; then : > >> >> >> >> >> + $as_echo_n "(cached) " >&6 > >> >> >> >> >> +else > >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> +EOF > >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> >> >> >> >> + 2>&5 ; then > >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> +fi > >> >> >> >> >> +rm -f conftest* > >> >> >> >> >> +fi > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > >> >> >> >> >> +$as_echo "$libc_cv_gnu_retain" >&6; } > >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > >> >> >> >> >> + > >> >> >> >> >> +fi > >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> +have-gnu-retain = $libc_cv_gnu_retain" > >> >> >> >> >> + > >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> >> >> >> >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> >> >> >> >> @@ -5871,6 +5896,40 @@ fi > >> >> >> >> >> $as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> > >> >> >> >> >> > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> >> >> >> >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> >> >> >> >> +libc_linker_feature=no > >> >> >> >> >> +if test x"$gnu_ld" = x"yes"; then > >> >> >> >> >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> >> >> >> >> + if test -n "$libc_linker_check"; then > >> >> >> >> >> + cat > conftest.c <<EOF > >> >> >> >> >> +int _start (void) { return 42; } > >> >> >> >> >> +EOF > >> >> >> >> >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> >> >> >> >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> >> >> >> >> + -fPIC -shared -o conftest.so conftest.c > >> >> >> >> >> + 1>&5' > >> >> >> >> >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> >> >> >> >> + (eval $ac_try) 2>&5 > >> >> >> >> >> + ac_status=$? > >> >> >> >> >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> >> >> >> >> + test $ac_status = 0; }; } > >> >> >> >> >> + then > >> >> >> >> >> + libc_linker_feature=yes > >> >> >> >> >> + fi > >> >> >> >> >> + rm -f conftest* > >> >> >> >> >> + fi > >> >> >> >> >> +fi > >> >> >> >> >> +if test $libc_linker_feature = yes; then > >> >> >> >> >> + libc_cv_z_start_stop_gc=yes > >> >> >> >> >> +else > >> >> >> >> >> + libc_cv_z_start_stop_gc=no > >> >> >> >> >> +fi > >> >> >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> >> >> >> >> +$as_echo "$libc_linker_feature" >&6; } > >> >> >> >> >> +config_vars="$config_vars > >> >> >> >> >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> >> >> >> >> + > >> >> >> >> >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> >> >> >> >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> >> >> >> >> libc_linker_feature=no > >> >> >> >> >> diff --git a/configure.ac b/configure.ac > >> >> >> >> >> index fce967f2c2..cc47e56e82 100644 > >> >> >> >> >> --- a/configure.ac > >> >> >> >> >> +++ b/configure.ac > >> >> >> >> >> @@ -707,6 +707,23 @@ fi > >> >> >> >> >> rm -f conftest*]) > >> >> >> >> >> AC_SUBST(libc_cv_textrel_ifunc) > >> >> >> >> >> > >> >> >> >> >> +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > >> >> >> >> >> +AC_CACHE_CHECK([for GNU attribute retain support], > >> >> >> >> >> + libc_cv_gnu_retain, [dnl > >> >> >> >> >> +cat > conftest.c <<EOF > >> >> >> >> >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> >> >> >> >> +EOF > >> >> >> >> >> +libc_cv_gnu_retain=no > >> >> >> >> >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> >> >> >> >> + 2>&AS_MESSAGE_LOG_FD ; then > >> >> >> >> >> + libc_cv_gnu_retain=yes > >> >> >> >> >> +fi > >> >> >> >> >> +rm -f conftest*]) > >> >> >> >> >> +if test $libc_cv_gnu_retain = yes; then > >> >> >> >> >> + AC_DEFINE(HAVE_GNU_RETAIN) > >> >> >> >> >> +fi > >> >> >> >> >> +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > >> >> >> >> >> + > >> >> >> >> >> # Check if gcc warns about alias for function with incompatible types. > >> >> >> >> >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> >> >> >> >> libc_cv_gcc_incompatible_alias, [dnl > >> >> >> >> >> @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> >> >> >> >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> >> >> >> >> AC_SUBST(libc_cv_z_execstack) > >> >> >> >> >> > >> >> >> >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> >> >> >> >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> >> >> >> >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> >> >> >> >> + > >> >> >> >> >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> >> >> >> >> [-Wl,--no-dynamic-linker], > >> >> >> >> >> [libc_cv_no_dynamic_linker=yes], > >> >> >> >> >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> >> >> >> >> index 546fc26a7b..127ea656c2 100644 > >> >> >> >> >> --- a/include/libc-symbols.h > >> >> >> >> >> +++ b/include/libc-symbols.h > >> >> >> >> >> @@ -352,6 +352,12 @@ for linking") > >> >> >> >> >> > >> >> >> >> >> */ > >> >> >> >> >> > >> >> >> >> >> +#ifdef HAVE_GNU_RETAIN > >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> >> >> >> >> +#else > >> >> >> >> >> +# define attribute_used_retain __attribute__ ((__used__)) > >> >> >> >> >> +#endif > >> >> >> >> >> + > >> >> >> >> >> /* Symbol set support macros. */ > >> >> >> >> >> > >> >> >> >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> >> >> >> >> @@ -367,12 +373,12 @@ for linking") > >> >> >> >> >> /* When building a shared library, make the set section writable, > >> >> >> >> >> because it will need to be relocated at run time anyway. */ > >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> #else > >> >> >> >> >> # define _elf_set_element(set, symbol) \ > >> >> >> >> >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> - __attribute__ ((used, section (#set))) = &(symbol) > >> >> >> >> >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> >> >> >> >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> >> >> >> >> #endif > >> >> >> >> >> > >> >> >> >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> >> >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> >> >> index 12ce41038f..ad0d53bb49 100644 > >> >> >> >> >> --- a/libio/Makefile > >> >> >> >> >> +++ b/libio/Makefile > >> >> >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> >> >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> >> >> endif > >> >> >> >> >> + > >> >> >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static > >> >> >> >> >> +tests-static += tst-cleanup-default-static > >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> >> >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> >> >> >> >> + > >> >> >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> >> >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> >> >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> >> >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> >> >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> >> >> +endif > >> >> >> >> >> endif > >> >> >> >> >> > >> >> >> >> >> include ../Rules > >> >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> >> >> endif > >> >> >> >> >> > >> >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-default-static.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> + > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> >> + $(evaluate-test) > >> >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.o: tst-cleanup.c > >> >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> > > >> >> >> >> >Please add a separate .c file for each test to get the correct dependency. > >> >> >> >> > >> >> >> >> Changed this block to: > >> >> >> >> > >> >> >> >> @@ -224,6 +244,39 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> >> endif > >> >> >> >> > >> >> >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-default.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> +$(objpfx)tst-cleanup-default-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default-static.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-default-static.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> + > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > >> >> >> >> + $(compile.c) -o $@ > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc-static.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-start-stop-gc-static.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> + > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc-static.out > >> >> >> >> + cmp $^ > $@; \ > >> >> >> >> + $(evaluate-test) > >> >> >> >> +$(objpfx)tst-cleanup-nostart-stop-gc-static.c: tst-cleanup.c > >> >> >> >> + cp $< $@ > >> >> >> >> + > >> >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> >> $(common-objpfx)libio/; \ > >> >> >> >> > >> >> >> > > >> >> >> >"make clean" doesn't remove the generated files. The standard way in glibc > >> >> >> >is to add a *-static.c source. > >> >> >> > >> >> >> I'll use .INTERMEDIATE and $(eval $(call ..)) > >> >> >> > >> >> >> diff --git a/libio/Makefile b/libio/Makefile > >> >> >> index 12ce41038f..a9b44f04df 100644 > >> >> >> --- a/libio/Makefile > >> >> >> +++ b/libio/Makefile > >> >> >> @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > >> >> >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> >> >> $(objpfx)tst-bz24228-mem.out > >> >> >> endif > >> >> >> + > >> >> >> +tests += tst-cleanup-default tst-cleanup-default-static > >> >> >> +tests-static += tst-cleanup-default-static > >> >> >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > >> >> >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> >> >> +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > >> >> >> + > >> >> >> +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > >> >> >> +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > >> >> >> + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > >> >> >> +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > >> >> >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > >> >> >> + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > >> >> >> +endif > >> >> >> endif > >> >> >> > >> >> >> include ../Rules > >> >> >> @@ -224,6 +244,17 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > >> >> >> $(objpfx)tst-wfile-sync.out: $(gen-locales) > >> >> >> endif > >> >> >> > >> >> >> +define gen-tst-cleanup > >> >> >> +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out > >> >> >> + cmp $$^ > $$@; $$(evaluate-test) > >> >> >> +$(objpfx)tst-cleanup-$1.c: tst-cleanup.c > >> >> >> + cp $$< $$@ > >> >> >> +.INTERMEDIATE: $(objpfx)tst-cleanup-$1.c > >> >> >> +endef > >> >> >> + > >> >> >> +$(foreach t, default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ > >> >> >> + $(eval $(call gen-tst-cleanup,$(t)))) > >> >> >> + > >> >> >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > >> >> >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > >> >> >> $(common-objpfx)libio/; \ > >> >> > > >> >> >There are 2 issues with static tests: > >> >> > > >> >> >1. A separate static source is needed. > >> >> > >> >> .INTERMEDIATE perfectly solves the lingering copied source issue. > >> >> I don't see lingering libio/tst-cleanup-*.c > >> > > >> >I was referring to > >> > > >> >elf/tst-array1-static.c > >> >elf/tst-array5-static.c > >> >elf/tst-dl-iter-static.c > >> >elf/tst-dst-static.c > >> >elf/tst-leaks1-static.c > >> >elf/tst-libc_dlvsym-static.c > >> >elf/tst-linkall-static.c > >> >elf/tst-ptrguard1-static.c > >> >elf/tst-single_threaded-pthread-static.c > >> >elf/tst-single_threaded-static.c > >> >elf/tst-stackguard1-static.c > >> >elf/tst-tls1-static.c > >> >elf/tst-tls2-static.c > >> >elf/tst-tls9-static.c > >> >elf/tst-tlsalign-extern-static.c > >> >elf/tst-tlsalign-static.c > >> >gmon/tst-gmon-static.c > >> >gmon/tst-profile-static.c > >> >localedata/bug-setlocale1-static.c > >> >localedata/tst-langinfo-newlocale-static.c > >> >localedata/tst-langinfo-setlocale-static.c > >> >localedata/tst-langinfo-static.c > >> >malloc/tst-malloc-usable-static.c > >> >math/test-fpucw-ieee-static.c > >> >math/test-fpucw-static.c > >> >math/test-signgam-uchar-init-static.c > >> >math/test-signgam-uchar-static.c > >> >math/test-signgam-uint-init-static.c > >> >math/test-signgam-uint-static.c > >> >math/test-signgam-ullong-init-static.c > >> >math/test-signgam-ullong-static.c > >> >nptl/tst-mutex8-static.c > >> >nptl/tst-mutexpi8-static.c > >> >nptl/tst-sem11-static.c > >> >nptl/tst-sem12-static.c > >> >nptl/tst-setuid1-static.c > >> >nptl/tst-stackguard1-static.c > >> >nss/tst-nss-static.c > >> >posix/tst-exec-static.c > >> >posix/tst-spawn-static.c > >> >setjmp/tst-setjmp-static.c > >> > > >> >> >2. We need to add the static test to both tests and tests-static. > >> >> > >> >> tests-static suffices. I have checked some tests-static usage in other > >> >> directories. > >> > > >> >There are > >> > > >> >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > >> > tst-sigsetjmp tst-setjmp-static > >> >tests-static := tst-setjmp-static > >> > > >> >They should be replaced by something like > >> > > >> >tests := tst-setjmp jmpbug bug269-setjmp tst-setjmp-fp \ > >> > tst-sigsetjmp > >> >tests-static-add := tst-setjmp-static > >> > >> Re-checking, the tst-cleanup* targets are in tests-special so `make tests` will build them. > >> If a tests-static target is not in tests-internal/tests-special, looks like it needs to be in tests. > >> > >> As is, I think my usage is correct. > >> > > > >The current glibc convention is to use > > > >[hjl@gnu-cfl-2 x86-glibc]$ cat elf/tst-tls9-static.c > >#include "tst-tls9.c" > >[hjl@gnu-cfl-2 x86-glibc]$ > > > >to test both dynamic and static libc. If we want to use a single > >source, we should create > >a framework to cover all such tests. > > OK. Dropped cp $< $@ and .INTERMEDIATE > > > From e937ae26a4a9a8ff6b1198f347f0b141a9285305 Mon Sep 17 00:00:00 2001 > From: Fangrui Song <maskray@google.com> > Date: Tue, 6 Apr 2021 14:45:01 -0700 > Subject: [PATCH] Set the retain attribute on _elf_set_element if CC supports > [BZ #27492] > MIME-Version: 1.0 > Content-Type: text/plain; charset=UTF-8 > Content-Transfer-Encoding: 8bit > > So that text_set_element/data_set_element/bss_set_element defined > variables will be retained by the linker. > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > will not be optimized out; 'retain' prevents section garbage collection > if the linker support SHF_GNU_RETAIN. > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > identifier name sections to be GCed even if there are live > __start_/__stop_ references. > > Without the change, there are some static linking problems, e.g. > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > stdout is not flushed on exit. > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > --- > config.h.in | 3 ++ > configure | 59 ++++++++++++++++++++++ > configure.ac | 21 ++++++++ > include/libc-symbols.h | 14 +++-- > libio/Makefile | 28 ++++++++++ > libio/tst-cleanup-default-static.c | 1 + > libio/tst-cleanup-default.c | 1 + > libio/tst-cleanup-nostart-stop-gc-static.c | 1 + > libio/tst-cleanup-nostart-stop-gc.c | 1 + > libio/tst-cleanup-start-stop-gc-static.c | 1 + > libio/tst-cleanup-start-stop-gc.c | 1 + > libio/tst-cleanup.c | 34 +++++++++++++ > libio/tst-cleanup.exp | 1 + > 13 files changed, 162 insertions(+), 4 deletions(-) > create mode 100644 libio/tst-cleanup-default-static.c > create mode 100644 libio/tst-cleanup-default.c > create mode 100644 libio/tst-cleanup-nostart-stop-gc-static.c > create mode 100644 libio/tst-cleanup-nostart-stop-gc.c > create mode 100644 libio/tst-cleanup-start-stop-gc-static.c > create mode 100644 libio/tst-cleanup-start-stop-gc.c > create mode 100644 libio/tst-cleanup.c > create mode 100644 libio/tst-cleanup.exp > > diff --git a/config.h.in b/config.h.in > index ca1547ae67..96a08c7757 100644 > --- a/config.h.in > +++ b/config.h.in > @@ -187,6 +187,9 @@ > /* Define if gcc supports attribute ifunc. */ > #undef HAVE_GCC_IFUNC > > +/* Define if CC supports attribute retain. */ > +#undef HAVE_GNU_RETAIN > + > /* Define if the linker defines __ehdr_start. */ > #undef HAVE_EHDR_START > > diff --git a/configure b/configure > index fcf43bf7de..e64b7f8efe 100755 > --- a/configure > +++ b/configure > @@ -4105,6 +4105,31 @@ fi > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for GNU attribute retain support" >&5 > +$as_echo_n "checking for GNU attribute retain support... " >&6; } > +if ${libc_cv_gnu_retain+:} false; then : > + $as_echo_n "(cached) " >&6 > +else > + cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gnu_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > + 2>&5 ; then > + libc_cv_gnu_retain=yes > +fi > +rm -f conftest* > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gnu_retain" >&5 > +$as_echo "$libc_cv_gnu_retain" >&6; } > +if test $libc_cv_gnu_retain = yes; then > + $as_echo "#define HAVE_GNU_RETAIN 1" >>confdefs.h > + > +fi > +config_vars="$config_vars > +have-gnu-retain = $libc_cv_gnu_retain" > + > # Check if gcc warns about alias for function with incompatible types. > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > @@ -5871,6 +5896,40 @@ fi > $as_echo "$libc_linker_feature" >&6; } > > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > +libc_linker_feature=no > +if test x"$gnu_ld" = x"yes"; then > + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > + if test -n "$libc_linker_check"; then > + cat > conftest.c <<EOF > +int _start (void) { return 42; } > +EOF > + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > + -fPIC -shared -o conftest.so conftest.c > + 1>&5' > + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > + (eval $ac_try) 2>&5 > + ac_status=$? > + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > + test $ac_status = 0; }; } > + then > + libc_linker_feature=yes > + fi > + rm -f conftest* > + fi > +fi > +if test $libc_linker_feature = yes; then > + libc_cv_z_start_stop_gc=yes > +else > + libc_cv_z_start_stop_gc=no > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > +$as_echo "$libc_linker_feature" >&6; } > +config_vars="$config_vars > +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > + > { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > libc_linker_feature=no > diff --git a/configure.ac b/configure.ac > index fce967f2c2..cc47e56e82 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -707,6 +707,23 @@ fi > rm -f conftest*]) > AC_SUBST(libc_cv_textrel_ifunc) > > +# Check if CC supports attribute retain as it is used in attribute_used_retain macro. > +AC_CACHE_CHECK([for GNU attribute retain support], > + libc_cv_gnu_retain, [dnl > +cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gnu_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > + 2>&AS_MESSAGE_LOG_FD ; then > + libc_cv_gnu_retain=yes > +fi > +rm -f conftest*]) > +if test $libc_cv_gnu_retain = yes; then > + AC_DEFINE(HAVE_GNU_RETAIN) > +fi > +LIBC_CONFIG_VAR([have-gnu-retain], [$libc_cv_gnu_retain]) > + > # Check if gcc warns about alias for function with incompatible types. > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > libc_cv_gcc_incompatible_alias, [dnl > @@ -1317,6 +1334,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > AC_SUBST(libc_cv_z_execstack) > > +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > + > LIBC_LINKER_FEATURE([--no-dynamic-linker], > [-Wl,--no-dynamic-linker], > [libc_cv_no_dynamic_linker=yes], > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > index 546fc26a7b..127ea656c2 100644 > --- a/include/libc-symbols.h > +++ b/include/libc-symbols.h > @@ -352,6 +352,12 @@ for linking") > > */ > > +#ifdef HAVE_GNU_RETAIN > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > +#else > +# define attribute_used_retain __attribute__ ((__used__)) > +#endif > + > /* Symbol set support macros. */ > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > @@ -367,12 +373,12 @@ for linking") > /* When building a shared library, make the set section writable, > because it will need to be relocated at run time anyway. */ > # define _elf_set_element(set, symbol) \ > - static const void *__elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *__elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #else > # define _elf_set_element(set, symbol) \ > - static const void *const __elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #endif > > /* Define SET as a symbol set. This may be required (it is in a.out) to > diff --git a/libio/Makefile b/libio/Makefile > index 12ce41038f..ed0ce4ee81 100644 > --- a/libio/Makefile > +++ b/libio/Makefile > @@ -195,6 +195,26 @@ ifeq (yes,$(build-shared)) > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > $(objpfx)tst-bz24228-mem.out > endif > + > +tests += tst-cleanup-default tst-cleanup-default-static > +tests-static += tst-cleanup-default-static > +tests-special += $(objpfx)tst-cleanup-default-cmp.out $(objpfx)tst-cleanup-default-static-cmp.out > +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > +LDFLAGS-tst-cleanup-default-static = -Wl,--gc-sections > + > +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > +tests += tst-cleanup-start-stop-gc tst-cleanup-start-stop-gc-static \ > + tst-cleanup-nostart-stop-gc tst-cleanup-nostart-stop-gc-static > +tests-static += tst-cleanup-start-stop-gc-static tst-cleanup-nostart-stop-gc-static > +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-start-stop-gc-static-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-static-cmp.out > +LDFLAGS-tst-cleanup-start-stop-gc := -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-start-stop-gc-static := -Wl,--gc-sections,-z,start-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc := -Wl,--gc-sections,-z,nostart-stop-gc > +LDFLAGS-tst-cleanup-nostart-stop-gc-static := -Wl,--gc-sections,-z,nostart-stop-gc > +endif > endif > > include ../Rules > @@ -224,6 +244,14 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +define gen-tst-cleanup > +$(objpfx)tst-cleanup-$1-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-$1.out > + cmp $$^ > $$@; $$(evaluate-test) > +endef > + > +$(foreach t,default default-static start-stop-gc start-stop-gc-static nostart-stop-gc nostart-stop-gc-static, \ > + $(eval $(call gen-tst-cleanup,$(t)))) > + > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ > diff --git a/libio/tst-cleanup-default-static.c b/libio/tst-cleanup-default-static.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-default-static.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-default.c b/libio/tst-cleanup-default.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-default.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-nostart-stop-gc-static.c b/libio/tst-cleanup-nostart-stop-gc-static.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-nostart-stop-gc-static.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-nostart-stop-gc.c b/libio/tst-cleanup-nostart-stop-gc.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-nostart-stop-gc.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-start-stop-gc-static.c b/libio/tst-cleanup-start-stop-gc-static.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-start-stop-gc-static.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup-start-stop-gc.c b/libio/tst-cleanup-start-stop-gc.c > new file mode 100644 > index 0000000000..c39956e2a8 > --- /dev/null > +++ b/libio/tst-cleanup-start-stop-gc.c > @@ -0,0 +1 @@ > +#include "tst-cleanup.c" > diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > new file mode 100644 > index 0000000000..837feac164 > --- /dev/null > +++ b/libio/tst-cleanup.c > @@ -0,0 +1,34 @@ > +/* Copyright (C) 2021 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + <https://www.gnu.org/licenses/>. */ > + > +/* Test that stdout is flushed after atexit callbacks were run, even if the > + * executable is linked with --gc-sections. */ > + > +#include <stdio.h> > +#include <stdlib.h> > + > +void > +hook (void) > +{ > + puts ("hello"); > +} > + > +int > +main (void) > +{ > + atexit (hook); > +} > diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > new file mode 100644 > index 0000000000..ce01362503 > --- /dev/null > +++ b/libio/tst-cleanup.exp > @@ -0,0 +1 @@ > +hello > -- > 2.31.0.208.g409f899ff0-goog > LGTM. Thanks. -- H.J. ^ permalink raw reply [flat|nested] 40+ messages in thread
end of thread, other threads:[~2021-04-16 13:01 UTC | newest] Thread overview: 40+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-03-15 1:10 [PATCH] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] Fangrui Song 2021-03-15 7:28 ` Florian Weimer 2021-03-15 7:45 ` Fāng-ruì Sòng 2021-03-15 8:13 ` Florian Weimer 2021-03-22 4:00 ` [PATCH v2] " Fangrui Song 2021-03-22 4:24 ` H.J. Lu 2021-03-22 4:40 ` Fangrui Song 2021-03-22 20:28 ` H.J. Lu 2021-03-23 4:14 ` Fangrui Song 2021-03-29 23:11 ` H.J. Lu 2021-03-29 23:24 ` [PATCH v3] " Fangrui Song 2021-03-30 18:17 ` H.J. Lu 2021-03-30 19:17 ` Fāng-ruì Sòng 2021-03-30 19:30 ` H.J. Lu 2021-03-31 4:34 ` Fāng-ruì Sòng 2021-03-31 16:17 ` H.J. Lu 2021-03-31 18:09 ` Fāng-ruì Sòng 2021-03-31 18:57 ` H.J. Lu 2021-03-31 19:39 ` [PATCH v4] " Fangrui Song 2021-03-31 23:38 ` H.J. Lu 2021-04-01 0:02 ` Fangrui Song 2021-04-01 1:00 ` H.J. Lu 2021-04-01 1:06 ` [PATCH v5] " Fangrui Song 2021-04-01 12:52 ` H.J. Lu 2021-04-02 3:23 ` Fangrui Song 2021-04-02 14:14 ` H.J. Lu 2021-04-02 17:09 ` Fangrui Song 2021-04-02 17:33 ` H.J. Lu 2021-04-03 18:02 ` Fangrui Song 2021-04-03 20:47 ` H.J. Lu 2021-04-03 21:57 ` Fangrui Song 2021-04-05 1:55 ` H.J. Lu 2021-04-05 18:17 ` Fangrui Song 2021-04-05 20:35 ` H.J. Lu 2021-04-05 21:03 ` Fangrui Song 2021-04-05 21:58 ` H.J. Lu 2021-04-06 21:46 ` Fangrui Song 2021-04-09 22:36 ` Fāng-ruì Sòng 2021-04-16 3:51 ` Fāng-ruì Sòng 2021-04-16 13:00 ` H.J. Lu
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