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Lu" Cc: GNU C Library , Florian Weimer Subject: Re: [PATCH v5] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] Message-ID: <20210405181702.46i742yevcjiazgn@google.com> References: <20210401010657.3474569-1-maskray@google.com> <20210402032329.c5d3zzlrtm3d3do3@google.com> <20210403180245.el7x24zpg4icg26k@google.com> <20210403215730.3hjzutts6fty7jji@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Spam-Status: No, score=-26.3 required=5.0 tests=BAYES_00, DKIMWL_WL_MED, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, ENV_AND_HDR_SPF_MATCH, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP, URIBL_BLACK, USER_IN_DEF_DKIM_WL, USER_IN_DEF_SPF_WL autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Apr 2021 18:17:11 -0000 On 2021-04-04, H.J. Lu wrote: >On Sat, Apr 3, 2021 at 2:57 PM Fangrui Song wrote: >> >> On 2021-04-03, H.J. Lu wrote: >> >On Sat, Apr 3, 2021 at 11:02 AM Fangrui Song wrote: >> >> >> >> >> >> On 2021-04-02, H.J. Lu wrote: >> >> >On Thu, Apr 1, 2021 at 8:23 PM Fangrui Song wrote: >> >> >> >> >> >> On 2021-04-01, H.J. Lu wrote: >> >> >> >On Wed, Mar 31, 2021 at 6:07 PM Fangrui Song 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 <> >> >> >> +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 <> >> >> >> +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 <> >> >> >> +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 >> >> >> >> + . */ >> >> >> >> + >> >> >> >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> >> >> >> + >> >> >> >> +#include >> >> >> >> +#include >> >> >> >> + >> >> >> >> +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 <> >> >> +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 <> >> >> +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 <> >> >> +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.