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* [glibc/azanella/rtld-shared] elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
@ 2021-08-09 20:17 Adhemerval Zanella
  0 siblings, 0 replies; 6+ messages in thread
From: Adhemerval Zanella @ 2021-08-09 20:17 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=83dc194adfa8e5b0747947806409a4582369da24

commit 83dc194adfa8e5b0747947806409a4582369da24
Author: Vivek Das Mohapatra <vivek@collabora.com>
Date:   Thu Jul 8 17:32:51 2021 +0100

    elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
    
    libc.so, libpthread.so etc should have the new unique-dso-by-default
    flag set to allow dlmopen to work better (libc et al instance shared
    by default when DSOs dlmopened into a new namespace).
    
    Checked on x86_64-linux-gnu and i686-linux-gnu.
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 Makeconfig                |  3 +++
 Makerules                 | 18 +++++++++++++++++-
 config.make.in            |  1 +
 configure                 | 48 ++++++++++++++++++++++++++++++++++++++++++++---
 configure.ac              | 23 ++++++++++++++++++++---
 elf/Makefile              |  3 +++
 elf/dynamic-notes.c       |  4 ++++
 extra-lib.mk              |  3 +++
 htl/Makefile              |  3 +++
 iconvdata/Makefile        |  3 +++
 iconvdata/extra-module.mk |  4 ++++
 11 files changed, 106 insertions(+), 7 deletions(-)

diff --git a/Makeconfig b/Makeconfig
index 68663d984e..1046ebb291 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -398,6 +398,9 @@ LDFLAGS-lib.so += -Wl,-z,now
 # Extra flags for dynamically linked non-test main programs.
 link-extra-flags += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS-lib.so += -Wl,-z,unique
+endif
 
 # Command to run after every final link (executable or shared object).
 # This is invoked with $(call after-link,...), so it should operate on
diff --git a/Makerules b/Makerules
index 596fa68376..66c1251754 100644
--- a/Makerules
+++ b/Makerules
@@ -581,7 +581,8 @@ $(common-objpfx)shlib.lds: $(common-objpfx)config.make $(..)Makerules
 		 PROVIDE(__start___libc_IO_vtables = .);\
 		 __libc_IO_vtables : { *(__libc_IO_vtables) }\
 		 PROVIDE(__stop___libc_IO_vtables = .);\
-		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@'
+		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@' \
+	      -e 's/^.*\*(\.dynamic).*$$/   .dynamic : { *dynamic-notes.os(.dynamic) *(.dynamic) }/'
 	test -s $@T
 	mv -f $@T $@
 common-generated += shlib.lds
@@ -636,6 +637,16 @@ build-shlib-objlist = $(build-module-helper-objlist) \
 # Also omits crti.o and crtn.o, which we do not want
 # since we define our own `.init' section specially.
 LDFLAGS-c.so = -nostdlib -nostartfiles
+
+# The stub dynamic-notes.os should not have weak/undefined symbol magic in it.
+# It's not really part of the internals, rather it is a vector for linker magic
+# which we need when the linker isn't new enough:
+%/dynamic-notes.os: CPPFLAGS += -UMODULE_NAME
+
+ifeq ($(ld-zunique),yes)
+LDFLAGS-c.so += -Wl,-z,unique
+endif
+
 # But we still want to link libc.so against $(libc.so-gnulib).
 LDLIBS-c.so += $(libc.so-gnulib)
 # Give libc.so an entry point and make it directly runnable itself.
@@ -706,6 +717,11 @@ $(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \
 	$(build-shlib)
 	$(call after-link,$@)
 
+ifneq ($(ld-zunique),yes)
+$(common-objpfx)libc.so: $(common-objpfx)elf/dynamic-notes.os
+$(common-objpfx)linkobj/libc.so: $(common-objpfx)elf/dynamic-notes.os
+endif
+
 ifeq ($(build-shared),yes)
 $(common-objpfx)libc.so: $(common-objpfx)libc.map
 endif
diff --git a/config.make.in b/config.make.in
index cbf59114b0..8755490c13 100644
--- a/config.make.in
+++ b/config.make.in
@@ -72,6 +72,7 @@ have-cc-with-libunwind = @libc_cv_cc_with_libunwind@
 fno-unit-at-a-time = @fno_unit_at_a_time@
 bind-now = @bindnow@
 have-hash-style = @libc_cv_hashstyle@
+ld-zunique = @ld_zunique@
 use-default-link = @use_default_link@
 have-cxx-thread_local = @libc_cv_cxx_thread_local@
 have-loop-to-function = @libc_cv_cc_loop_to_function@
diff --git a/configure b/configure
index 9619c10991..3e6d7ffc49 100755
--- a/configure
+++ b/configure
@@ -625,6 +625,7 @@ libc_cv_cc_nofma
 libc_cv_mtls_dialect_gnu2
 fno_unit_at_a_time
 libc_cv_has_glob_dat
+ld_zunique
 libc_cv_hashstyle
 libc_cv_fpie
 libc_cv_z_execstack
@@ -6074,9 +6075,44 @@ fi
 $as_echo "$libc_cv_hashstyle" >&6; }
 
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support" >&5
+$as_echo_n "checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support... " >&6; }
+if { as_var=cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext; eval \${$as_var+:} false; }; then :
+  $as_echo_n "(cached) " >&6
+fi
+eval ac_res=\$cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+LDFLAGS="$old_LDFLAGS"
+
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sufficient default -shared layout" >&5
 $as_echo_n "checking for sufficient default -shared layout... " >&6; }
@@ -6119,10 +6155,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&5 "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&5 "\
 $libc_seen_a$libc_seen_b from:
diff --git a/configure.ac b/configure.ac
index 34ecbba540..6a443007fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1372,9 +1372,20 @@ fi
 rm -f conftest*])
 AC_SUBST(libc_cv_hashstyle)
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+AC_CACHE_CHECK([for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support],
+	       AC_LINK_IFELSE([AC_LANG_SOURCE([void foo (void) { }])],
+			      libc_cv_ld_zunique=yes,
+			      libc_cv_ld_zunique=no))
+LDFLAGS="$old_LDFLAGS"
+AC_SUBST(ld_zunique)
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   AC_CACHE_CHECK([for sufficient default -shared layout],
 		  libc_cv_use_default_link, [dnl
@@ -1410,10 +1421,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&AS_MESSAGE_LOG_FD "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&AS_MESSAGE_LOG_FD "\
 $libc_seen_a$libc_seen_b from:
diff --git a/elf/Makefile b/elf/Makefile
index d05f410592..f33a761c93 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -103,6 +103,9 @@ endif
 
 ifeq (yes,$(build-shared))
 extra-objs	= $(all-rtld-routines:%=%.os) sofini.os interp.os
+ifneq (yes,$(ld-zunique))
+extra-objs      += dynamic-notes.os
+endif
 generated	+= librtld.os dl-allobjs.os ld.so ldd
 install-others	= $(inst_rtlddir)/$(rtld-installed-name)
 install-bin-script = ldd
diff --git a/elf/dynamic-notes.c b/elf/dynamic-notes.c
new file mode 100644
index 0000000000..d0b487e970
--- /dev/null
+++ b/elf/dynamic-notes.c
@@ -0,0 +1,4 @@
+#include <link.h>
+
+const ElfW(Dyn) __dynamic_note __attribute__ ((section (".dynamic"))) =
+  { .d_tag = DT_GNU_FLAGS_1, .d_un.d_val = DF_GNU_1_UNIQUE };
diff --git a/extra-lib.mk b/extra-lib.mk
index 72f8d2e1df..9051958ec0 100644
--- a/extra-lib.mk
+++ b/extra-lib.mk
@@ -101,6 +101,9 @@ $(objpfx)$(lib).so: $(firstword $($(lib)-map) \
 				$(addprefix $(common-objpfx), \
 					    $(filter $(lib).map, \
 						     $(version-maps))))
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(lib).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
 endif
 
 endif
diff --git a/htl/Makefile b/htl/Makefile
index cf9d12fc12..c2a25dcd79 100644
--- a/htl/Makefile
+++ b/htl/Makefile
@@ -203,6 +203,9 @@ libc-link.so = $(common-objpfx)libc.so
 
 extra-B-pthread.so = -B$(common-objpfx)htl/
 LDFLAGS-pthread.so = -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst
+ifeq ($(ld-zunique),yes)
+LDFLAGS-pthread.so += -Wl,-z,unique
+endif
 
 include ../Rules
 
diff --git a/iconvdata/Makefile b/iconvdata/Makefile
index c216f959df..b1b46e5a43 100644
--- a/iconvdata/Makefile
+++ b/iconvdata/Makefile
@@ -67,6 +67,9 @@ modules	:= ISO8859-1 ISO8859-2 ISO8859-3 ISO8859-4 ISO8859-5		 \
 ifeq ($(bind-now),yes)
 LDFLAGS.so += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS.so += -Wl,-z,unique
+endif
 
 modules.so := $(addsuffix .so, $(modules))
 
diff --git a/iconvdata/extra-module.mk b/iconvdata/extra-module.mk
index ecaf507624..92c3ab4d7b 100644
--- a/iconvdata/extra-module.mk
+++ b/iconvdata/extra-module.mk
@@ -7,6 +7,10 @@ $(objpfx)$(mod).so: $(addprefix $(objpfx),$(addsuffix .os,$($(mod)-routines)))\
 		    $(shlib-lds) $(link-libc-deps)
 	$(build-module-asneeded)
 
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(mod).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
+
 ifneq (,$(extra-modules-left))
 include extra-module.mk
 endif


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/azanella/rtld-shared] elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
@ 2021-09-27 18:54 Adhemerval Zanella
  0 siblings, 0 replies; 6+ messages in thread
From: Adhemerval Zanella @ 2021-09-27 18:54 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9702f28ab810a8a2e8c7759f10fc8cab1ab8b11e

commit 9702f28ab810a8a2e8c7759f10fc8cab1ab8b11e
Author: Vivek Das Mohapatra <vivek@collabora.com>
Date:   Thu Jul 8 17:32:51 2021 +0100

    elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
    
    libc.so, libpthread.so etc should have the new unique-dso-by-default
    flag set to allow dlmopen to work better (libc et al instance shared
    by default when DSOs dlmopened into a new namespace).
    
    Checked on x86_64-linux-gnu and i686-linux-gnu.
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 Makeconfig                |  3 +++
 Makerules                 | 18 ++++++++++++++++-
 configure                 | 50 ++++++++++++++++++++++++++++++++++++++++++++---
 configure.ac              | 24 ++++++++++++++++++++---
 elf/Makefile              |  3 +++
 elf/dynamic-notes.c       |  4 ++++
 extra-lib.mk              |  3 +++
 iconvdata/Makefile        |  3 +++
 iconvdata/extra-module.mk |  4 ++++
 9 files changed, 105 insertions(+), 7 deletions(-)

diff --git a/Makeconfig b/Makeconfig
index 2fa0884b4e..ae587ce84e 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -398,6 +398,9 @@ LDFLAGS-lib.so += -Wl,-z,now
 # Extra flags for dynamically linked non-test main programs.
 link-extra-flags += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS-lib.so += -Wl,-z,unique
+endif
 
 # Command to run after every final link (executable or shared object).
 # This is invoked with $(call after-link,...), so it should operate on
diff --git a/Makerules b/Makerules
index 596fa68376..66c1251754 100644
--- a/Makerules
+++ b/Makerules
@@ -581,7 +581,8 @@ $(common-objpfx)shlib.lds: $(common-objpfx)config.make $(..)Makerules
 		 PROVIDE(__start___libc_IO_vtables = .);\
 		 __libc_IO_vtables : { *(__libc_IO_vtables) }\
 		 PROVIDE(__stop___libc_IO_vtables = .);\
-		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@'
+		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@' \
+	      -e 's/^.*\*(\.dynamic).*$$/   .dynamic : { *dynamic-notes.os(.dynamic) *(.dynamic) }/'
 	test -s $@T
 	mv -f $@T $@
 common-generated += shlib.lds
@@ -636,6 +637,16 @@ build-shlib-objlist = $(build-module-helper-objlist) \
 # Also omits crti.o and crtn.o, which we do not want
 # since we define our own `.init' section specially.
 LDFLAGS-c.so = -nostdlib -nostartfiles
+
+# The stub dynamic-notes.os should not have weak/undefined symbol magic in it.
+# It's not really part of the internals, rather it is a vector for linker magic
+# which we need when the linker isn't new enough:
+%/dynamic-notes.os: CPPFLAGS += -UMODULE_NAME
+
+ifeq ($(ld-zunique),yes)
+LDFLAGS-c.so += -Wl,-z,unique
+endif
+
 # But we still want to link libc.so against $(libc.so-gnulib).
 LDLIBS-c.so += $(libc.so-gnulib)
 # Give libc.so an entry point and make it directly runnable itself.
@@ -706,6 +717,11 @@ $(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \
 	$(build-shlib)
 	$(call after-link,$@)
 
+ifneq ($(ld-zunique),yes)
+$(common-objpfx)libc.so: $(common-objpfx)elf/dynamic-notes.os
+$(common-objpfx)linkobj/libc.so: $(common-objpfx)elf/dynamic-notes.os
+endif
+
 ifeq ($(build-shared),yes)
 $(common-objpfx)libc.so: $(common-objpfx)libc.map
 endif
diff --git a/configure b/configure
index 39d75eb4ed..3f749b7635 100755
--- a/configure
+++ b/configure
@@ -625,6 +625,7 @@ libc_cv_cc_nofma
 libc_cv_mtls_dialect_gnu2
 fno_unit_at_a_time
 libc_cv_has_glob_dat
+libc_cv_ld_zunique
 libc_cv_hashstyle
 libc_cv_fpie
 libc_cv_z_execstack
@@ -6181,9 +6182,46 @@ fi
 $as_echo "$libc_cv_hashstyle" >&6; }
 
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support" >&5
+$as_echo_n "checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support... " >&6; }
+if { as_var=cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext; eval \${$as_var+:} false; }; then :
+  $as_echo_n "(cached) " >&6
+fi
+eval ac_res=\$cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+LDFLAGS="$old_LDFLAGS"
+
+config_vars="$config_vars
+ld_zunique = $libc_cv_ld_zunique"
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sufficient default -shared layout" >&5
 $as_echo_n "checking for sufficient default -shared layout... " >&6; }
@@ -6226,10 +6264,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&5 "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&5 "\
 $libc_seen_a$libc_seen_b from:
diff --git a/configure.ac b/configure.ac
index 00f49f09f7..928989fac5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1389,9 +1389,21 @@ fi
 rm -f conftest*])
 AC_SUBST(libc_cv_hashstyle)
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+AC_CACHE_CHECK([for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support],
+	       AC_LINK_IFELSE([AC_LANG_SOURCE([void foo (void) { }])],
+			      libc_cv_ld_zunique=yes,
+			      libc_cv_ld_zunique=no))
+LDFLAGS="$old_LDFLAGS"
+AC_SUBST(libc_cv_ld_zunique)
+LIBC_CONFIG_VAR([ld_zunique], [$libc_cv_ld_zunique])
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   AC_CACHE_CHECK([for sufficient default -shared layout],
 		  libc_cv_use_default_link, [dnl
@@ -1427,10 +1439,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&AS_MESSAGE_LOG_FD "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&AS_MESSAGE_LOG_FD "\
 $libc_seen_a$libc_seen_b from:
diff --git a/elf/Makefile b/elf/Makefile
index 26986c0692..d7eb7cf476 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -104,6 +104,9 @@ endif
 
 ifeq (yes,$(build-shared))
 extra-objs	= $(all-rtld-routines:%=%.os) sofini.os interp.os
+ifneq (yes,$(ld-zunique))
+extra-objs      += dynamic-notes.os
+endif
 generated	+= librtld.os dl-allobjs.os ld.so ldd
 install-others	= $(inst_rtlddir)/$(rtld-installed-name)
 install-bin-script = ldd
diff --git a/elf/dynamic-notes.c b/elf/dynamic-notes.c
new file mode 100644
index 0000000000..d0b487e970
--- /dev/null
+++ b/elf/dynamic-notes.c
@@ -0,0 +1,4 @@
+#include <link.h>
+
+const ElfW(Dyn) __dynamic_note __attribute__ ((section (".dynamic"))) =
+  { .d_tag = DT_GNU_FLAGS_1, .d_un.d_val = DF_GNU_1_UNIQUE };
diff --git a/extra-lib.mk b/extra-lib.mk
index 72f8d2e1df..9051958ec0 100644
--- a/extra-lib.mk
+++ b/extra-lib.mk
@@ -101,6 +101,9 @@ $(objpfx)$(lib).so: $(firstword $($(lib)-map) \
 				$(addprefix $(common-objpfx), \
 					    $(filter $(lib).map, \
 						     $(version-maps))))
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(lib).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
 endif
 
 endif
diff --git a/iconvdata/Makefile b/iconvdata/Makefile
index c216f959df..b1b46e5a43 100644
--- a/iconvdata/Makefile
+++ b/iconvdata/Makefile
@@ -67,6 +67,9 @@ modules	:= ISO8859-1 ISO8859-2 ISO8859-3 ISO8859-4 ISO8859-5		 \
 ifeq ($(bind-now),yes)
 LDFLAGS.so += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS.so += -Wl,-z,unique
+endif
 
 modules.so := $(addsuffix .so, $(modules))
 
diff --git a/iconvdata/extra-module.mk b/iconvdata/extra-module.mk
index ecaf507624..92c3ab4d7b 100644
--- a/iconvdata/extra-module.mk
+++ b/iconvdata/extra-module.mk
@@ -7,6 +7,10 @@ $(objpfx)$(mod).so: $(addprefix $(objpfx),$(addsuffix .os,$($(mod)-routines)))\
 		    $(shlib-lds) $(link-libc-deps)
 	$(build-module-asneeded)
 
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(mod).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
+
 ifneq (,$(extra-modules-left))
 include extra-module.mk
 endif


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/azanella/rtld-shared] elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
@ 2021-08-10 13:42 Adhemerval Zanella
  0 siblings, 0 replies; 6+ messages in thread
From: Adhemerval Zanella @ 2021-08-10 13:42 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=69b0cffd7362e5827a95df6a690f8dd1d9fb1e77

commit 69b0cffd7362e5827a95df6a690f8dd1d9fb1e77
Author: Vivek Das Mohapatra <vivek@collabora.com>
Date:   Thu Jul 8 17:32:51 2021 +0100

    elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
    
    libc.so, libpthread.so etc should have the new unique-dso-by-default
    flag set to allow dlmopen to work better (libc et al instance shared
    by default when DSOs dlmopened into a new namespace).
    
    Checked on x86_64-linux-gnu and i686-linux-gnu.
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 Makeconfig                |  3 +++
 Makerules                 | 18 ++++++++++++++++-
 configure                 | 50 ++++++++++++++++++++++++++++++++++++++++++++---
 configure.ac              | 24 ++++++++++++++++++++---
 elf/Makefile              |  3 +++
 elf/dynamic-notes.c       |  4 ++++
 extra-lib.mk              |  3 +++
 iconvdata/Makefile        |  3 +++
 iconvdata/extra-module.mk |  4 ++++
 9 files changed, 105 insertions(+), 7 deletions(-)

diff --git a/Makeconfig b/Makeconfig
index 68663d984e..1046ebb291 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -398,6 +398,9 @@ LDFLAGS-lib.so += -Wl,-z,now
 # Extra flags for dynamically linked non-test main programs.
 link-extra-flags += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS-lib.so += -Wl,-z,unique
+endif
 
 # Command to run after every final link (executable or shared object).
 # This is invoked with $(call after-link,...), so it should operate on
diff --git a/Makerules b/Makerules
index 596fa68376..66c1251754 100644
--- a/Makerules
+++ b/Makerules
@@ -581,7 +581,8 @@ $(common-objpfx)shlib.lds: $(common-objpfx)config.make $(..)Makerules
 		 PROVIDE(__start___libc_IO_vtables = .);\
 		 __libc_IO_vtables : { *(__libc_IO_vtables) }\
 		 PROVIDE(__stop___libc_IO_vtables = .);\
-		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@'
+		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@' \
+	      -e 's/^.*\*(\.dynamic).*$$/   .dynamic : { *dynamic-notes.os(.dynamic) *(.dynamic) }/'
 	test -s $@T
 	mv -f $@T $@
 common-generated += shlib.lds
@@ -636,6 +637,16 @@ build-shlib-objlist = $(build-module-helper-objlist) \
 # Also omits crti.o and crtn.o, which we do not want
 # since we define our own `.init' section specially.
 LDFLAGS-c.so = -nostdlib -nostartfiles
+
+# The stub dynamic-notes.os should not have weak/undefined symbol magic in it.
+# It's not really part of the internals, rather it is a vector for linker magic
+# which we need when the linker isn't new enough:
+%/dynamic-notes.os: CPPFLAGS += -UMODULE_NAME
+
+ifeq ($(ld-zunique),yes)
+LDFLAGS-c.so += -Wl,-z,unique
+endif
+
 # But we still want to link libc.so against $(libc.so-gnulib).
 LDLIBS-c.so += $(libc.so-gnulib)
 # Give libc.so an entry point and make it directly runnable itself.
@@ -706,6 +717,11 @@ $(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \
 	$(build-shlib)
 	$(call after-link,$@)
 
+ifneq ($(ld-zunique),yes)
+$(common-objpfx)libc.so: $(common-objpfx)elf/dynamic-notes.os
+$(common-objpfx)linkobj/libc.so: $(common-objpfx)elf/dynamic-notes.os
+endif
+
 ifeq ($(build-shared),yes)
 $(common-objpfx)libc.so: $(common-objpfx)libc.map
 endif
diff --git a/configure b/configure
index 9619c10991..e7eb4d1456 100755
--- a/configure
+++ b/configure
@@ -625,6 +625,7 @@ libc_cv_cc_nofma
 libc_cv_mtls_dialect_gnu2
 fno_unit_at_a_time
 libc_cv_has_glob_dat
+libc_cv_ld_zunique
 libc_cv_hashstyle
 libc_cv_fpie
 libc_cv_z_execstack
@@ -6074,9 +6075,46 @@ fi
 $as_echo "$libc_cv_hashstyle" >&6; }
 
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support" >&5
+$as_echo_n "checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support... " >&6; }
+if { as_var=cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext; eval \${$as_var+:} false; }; then :
+  $as_echo_n "(cached) " >&6
+fi
+eval ac_res=\$cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+LDFLAGS="$old_LDFLAGS"
+
+config_vars="$config_vars
+ld_zunique = $libc_cv_ld_zunique"
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sufficient default -shared layout" >&5
 $as_echo_n "checking for sufficient default -shared layout... " >&6; }
@@ -6119,10 +6157,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&5 "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&5 "\
 $libc_seen_a$libc_seen_b from:
diff --git a/configure.ac b/configure.ac
index 34ecbba540..711d012ed7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1372,9 +1372,21 @@ fi
 rm -f conftest*])
 AC_SUBST(libc_cv_hashstyle)
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+AC_CACHE_CHECK([for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support],
+	       AC_LINK_IFELSE([AC_LANG_SOURCE([void foo (void) { }])],
+			      libc_cv_ld_zunique=yes,
+			      libc_cv_ld_zunique=no))
+LDFLAGS="$old_LDFLAGS"
+AC_SUBST(libc_cv_ld_zunique)
+LIBC_CONFIG_VAR([ld_zunique], [$libc_cv_ld_zunique])
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   AC_CACHE_CHECK([for sufficient default -shared layout],
 		  libc_cv_use_default_link, [dnl
@@ -1410,10 +1422,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&AS_MESSAGE_LOG_FD "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&AS_MESSAGE_LOG_FD "\
 $libc_seen_a$libc_seen_b from:
diff --git a/elf/Makefile b/elf/Makefile
index d05f410592..f33a761c93 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -103,6 +103,9 @@ endif
 
 ifeq (yes,$(build-shared))
 extra-objs	= $(all-rtld-routines:%=%.os) sofini.os interp.os
+ifneq (yes,$(ld-zunique))
+extra-objs      += dynamic-notes.os
+endif
 generated	+= librtld.os dl-allobjs.os ld.so ldd
 install-others	= $(inst_rtlddir)/$(rtld-installed-name)
 install-bin-script = ldd
diff --git a/elf/dynamic-notes.c b/elf/dynamic-notes.c
new file mode 100644
index 0000000000..d0b487e970
--- /dev/null
+++ b/elf/dynamic-notes.c
@@ -0,0 +1,4 @@
+#include <link.h>
+
+const ElfW(Dyn) __dynamic_note __attribute__ ((section (".dynamic"))) =
+  { .d_tag = DT_GNU_FLAGS_1, .d_un.d_val = DF_GNU_1_UNIQUE };
diff --git a/extra-lib.mk b/extra-lib.mk
index 72f8d2e1df..9051958ec0 100644
--- a/extra-lib.mk
+++ b/extra-lib.mk
@@ -101,6 +101,9 @@ $(objpfx)$(lib).so: $(firstword $($(lib)-map) \
 				$(addprefix $(common-objpfx), \
 					    $(filter $(lib).map, \
 						     $(version-maps))))
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(lib).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
 endif
 
 endif
diff --git a/iconvdata/Makefile b/iconvdata/Makefile
index c216f959df..b1b46e5a43 100644
--- a/iconvdata/Makefile
+++ b/iconvdata/Makefile
@@ -67,6 +67,9 @@ modules	:= ISO8859-1 ISO8859-2 ISO8859-3 ISO8859-4 ISO8859-5		 \
 ifeq ($(bind-now),yes)
 LDFLAGS.so += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS.so += -Wl,-z,unique
+endif
 
 modules.so := $(addsuffix .so, $(modules))
 
diff --git a/iconvdata/extra-module.mk b/iconvdata/extra-module.mk
index ecaf507624..92c3ab4d7b 100644
--- a/iconvdata/extra-module.mk
+++ b/iconvdata/extra-module.mk
@@ -7,6 +7,10 @@ $(objpfx)$(mod).so: $(addprefix $(objpfx),$(addsuffix .os,$($(mod)-routines)))\
 		    $(shlib-lds) $(link-libc-deps)
 	$(build-module-asneeded)
 
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(mod).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
+
 ifneq (,$(extra-modules-left))
 include extra-module.mk
 endif


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/azanella/rtld-shared] elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
@ 2021-08-10 12:43 Adhemerval Zanella
  0 siblings, 0 replies; 6+ messages in thread
From: Adhemerval Zanella @ 2021-08-10 12:43 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=83dc194adfa8e5b0747947806409a4582369da24

commit 83dc194adfa8e5b0747947806409a4582369da24
Author: Vivek Das Mohapatra <vivek@collabora.com>
Date:   Thu Jul 8 17:32:51 2021 +0100

    elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
    
    libc.so, libpthread.so etc should have the new unique-dso-by-default
    flag set to allow dlmopen to work better (libc et al instance shared
    by default when DSOs dlmopened into a new namespace).
    
    Checked on x86_64-linux-gnu and i686-linux-gnu.
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 Makeconfig                |  3 +++
 Makerules                 | 18 +++++++++++++++++-
 config.make.in            |  1 +
 configure                 | 48 ++++++++++++++++++++++++++++++++++++++++++++---
 configure.ac              | 23 ++++++++++++++++++++---
 elf/Makefile              |  3 +++
 elf/dynamic-notes.c       |  4 ++++
 extra-lib.mk              |  3 +++
 htl/Makefile              |  3 +++
 iconvdata/Makefile        |  3 +++
 iconvdata/extra-module.mk |  4 ++++
 11 files changed, 106 insertions(+), 7 deletions(-)

diff --git a/Makeconfig b/Makeconfig
index 68663d984e..1046ebb291 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -398,6 +398,9 @@ LDFLAGS-lib.so += -Wl,-z,now
 # Extra flags for dynamically linked non-test main programs.
 link-extra-flags += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS-lib.so += -Wl,-z,unique
+endif
 
 # Command to run after every final link (executable or shared object).
 # This is invoked with $(call after-link,...), so it should operate on
diff --git a/Makerules b/Makerules
index 596fa68376..66c1251754 100644
--- a/Makerules
+++ b/Makerules
@@ -581,7 +581,8 @@ $(common-objpfx)shlib.lds: $(common-objpfx)config.make $(..)Makerules
 		 PROVIDE(__start___libc_IO_vtables = .);\
 		 __libc_IO_vtables : { *(__libc_IO_vtables) }\
 		 PROVIDE(__stop___libc_IO_vtables = .);\
-		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@'
+		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@' \
+	      -e 's/^.*\*(\.dynamic).*$$/   .dynamic : { *dynamic-notes.os(.dynamic) *(.dynamic) }/'
 	test -s $@T
 	mv -f $@T $@
 common-generated += shlib.lds
@@ -636,6 +637,16 @@ build-shlib-objlist = $(build-module-helper-objlist) \
 # Also omits crti.o and crtn.o, which we do not want
 # since we define our own `.init' section specially.
 LDFLAGS-c.so = -nostdlib -nostartfiles
+
+# The stub dynamic-notes.os should not have weak/undefined symbol magic in it.
+# It's not really part of the internals, rather it is a vector for linker magic
+# which we need when the linker isn't new enough:
+%/dynamic-notes.os: CPPFLAGS += -UMODULE_NAME
+
+ifeq ($(ld-zunique),yes)
+LDFLAGS-c.so += -Wl,-z,unique
+endif
+
 # But we still want to link libc.so against $(libc.so-gnulib).
 LDLIBS-c.so += $(libc.so-gnulib)
 # Give libc.so an entry point and make it directly runnable itself.
@@ -706,6 +717,11 @@ $(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \
 	$(build-shlib)
 	$(call after-link,$@)
 
+ifneq ($(ld-zunique),yes)
+$(common-objpfx)libc.so: $(common-objpfx)elf/dynamic-notes.os
+$(common-objpfx)linkobj/libc.so: $(common-objpfx)elf/dynamic-notes.os
+endif
+
 ifeq ($(build-shared),yes)
 $(common-objpfx)libc.so: $(common-objpfx)libc.map
 endif
diff --git a/config.make.in b/config.make.in
index cbf59114b0..8755490c13 100644
--- a/config.make.in
+++ b/config.make.in
@@ -72,6 +72,7 @@ have-cc-with-libunwind = @libc_cv_cc_with_libunwind@
 fno-unit-at-a-time = @fno_unit_at_a_time@
 bind-now = @bindnow@
 have-hash-style = @libc_cv_hashstyle@
+ld-zunique = @ld_zunique@
 use-default-link = @use_default_link@
 have-cxx-thread_local = @libc_cv_cxx_thread_local@
 have-loop-to-function = @libc_cv_cc_loop_to_function@
diff --git a/configure b/configure
index 9619c10991..3e6d7ffc49 100755
--- a/configure
+++ b/configure
@@ -625,6 +625,7 @@ libc_cv_cc_nofma
 libc_cv_mtls_dialect_gnu2
 fno_unit_at_a_time
 libc_cv_has_glob_dat
+ld_zunique
 libc_cv_hashstyle
 libc_cv_fpie
 libc_cv_z_execstack
@@ -6074,9 +6075,44 @@ fi
 $as_echo "$libc_cv_hashstyle" >&6; }
 
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support" >&5
+$as_echo_n "checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support... " >&6; }
+if { as_var=cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext; eval \${$as_var+:} false; }; then :
+  $as_echo_n "(cached) " >&6
+fi
+eval ac_res=\$cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+LDFLAGS="$old_LDFLAGS"
+
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sufficient default -shared layout" >&5
 $as_echo_n "checking for sufficient default -shared layout... " >&6; }
@@ -6119,10 +6155,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&5 "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&5 "\
 $libc_seen_a$libc_seen_b from:
diff --git a/configure.ac b/configure.ac
index 34ecbba540..6a443007fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1372,9 +1372,20 @@ fi
 rm -f conftest*])
 AC_SUBST(libc_cv_hashstyle)
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+AC_CACHE_CHECK([for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support],
+	       AC_LINK_IFELSE([AC_LANG_SOURCE([void foo (void) { }])],
+			      libc_cv_ld_zunique=yes,
+			      libc_cv_ld_zunique=no))
+LDFLAGS="$old_LDFLAGS"
+AC_SUBST(ld_zunique)
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   AC_CACHE_CHECK([for sufficient default -shared layout],
 		  libc_cv_use_default_link, [dnl
@@ -1410,10 +1421,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&AS_MESSAGE_LOG_FD "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&AS_MESSAGE_LOG_FD "\
 $libc_seen_a$libc_seen_b from:
diff --git a/elf/Makefile b/elf/Makefile
index d05f410592..f33a761c93 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -103,6 +103,9 @@ endif
 
 ifeq (yes,$(build-shared))
 extra-objs	= $(all-rtld-routines:%=%.os) sofini.os interp.os
+ifneq (yes,$(ld-zunique))
+extra-objs      += dynamic-notes.os
+endif
 generated	+= librtld.os dl-allobjs.os ld.so ldd
 install-others	= $(inst_rtlddir)/$(rtld-installed-name)
 install-bin-script = ldd
diff --git a/elf/dynamic-notes.c b/elf/dynamic-notes.c
new file mode 100644
index 0000000000..d0b487e970
--- /dev/null
+++ b/elf/dynamic-notes.c
@@ -0,0 +1,4 @@
+#include <link.h>
+
+const ElfW(Dyn) __dynamic_note __attribute__ ((section (".dynamic"))) =
+  { .d_tag = DT_GNU_FLAGS_1, .d_un.d_val = DF_GNU_1_UNIQUE };
diff --git a/extra-lib.mk b/extra-lib.mk
index 72f8d2e1df..9051958ec0 100644
--- a/extra-lib.mk
+++ b/extra-lib.mk
@@ -101,6 +101,9 @@ $(objpfx)$(lib).so: $(firstword $($(lib)-map) \
 				$(addprefix $(common-objpfx), \
 					    $(filter $(lib).map, \
 						     $(version-maps))))
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(lib).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
 endif
 
 endif
diff --git a/htl/Makefile b/htl/Makefile
index cf9d12fc12..c2a25dcd79 100644
--- a/htl/Makefile
+++ b/htl/Makefile
@@ -203,6 +203,9 @@ libc-link.so = $(common-objpfx)libc.so
 
 extra-B-pthread.so = -B$(common-objpfx)htl/
 LDFLAGS-pthread.so = -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst
+ifeq ($(ld-zunique),yes)
+LDFLAGS-pthread.so += -Wl,-z,unique
+endif
 
 include ../Rules
 
diff --git a/iconvdata/Makefile b/iconvdata/Makefile
index c216f959df..b1b46e5a43 100644
--- a/iconvdata/Makefile
+++ b/iconvdata/Makefile
@@ -67,6 +67,9 @@ modules	:= ISO8859-1 ISO8859-2 ISO8859-3 ISO8859-4 ISO8859-5		 \
 ifeq ($(bind-now),yes)
 LDFLAGS.so += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS.so += -Wl,-z,unique
+endif
 
 modules.so := $(addsuffix .so, $(modules))
 
diff --git a/iconvdata/extra-module.mk b/iconvdata/extra-module.mk
index ecaf507624..92c3ab4d7b 100644
--- a/iconvdata/extra-module.mk
+++ b/iconvdata/extra-module.mk
@@ -7,6 +7,10 @@ $(objpfx)$(mod).so: $(addprefix $(objpfx),$(addsuffix .os,$($(mod)-routines)))\
 		    $(shlib-lds) $(link-libc-deps)
 	$(build-module-asneeded)
 
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(mod).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
+
 ifneq (,$(extra-modules-left))
 include extra-module.mk
 endif


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/azanella/rtld-shared] elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
@ 2021-08-09 20:31 Adhemerval Zanella
  0 siblings, 0 replies; 6+ messages in thread
From: Adhemerval Zanella @ 2021-08-09 20:31 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=83dc194adfa8e5b0747947806409a4582369da24

commit 83dc194adfa8e5b0747947806409a4582369da24
Author: Vivek Das Mohapatra <vivek@collabora.com>
Date:   Thu Jul 8 17:32:51 2021 +0100

    elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
    
    libc.so, libpthread.so etc should have the new unique-dso-by-default
    flag set to allow dlmopen to work better (libc et al instance shared
    by default when DSOs dlmopened into a new namespace).
    
    Checked on x86_64-linux-gnu and i686-linux-gnu.
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 Makeconfig                |  3 +++
 Makerules                 | 18 +++++++++++++++++-
 config.make.in            |  1 +
 configure                 | 48 ++++++++++++++++++++++++++++++++++++++++++++---
 configure.ac              | 23 ++++++++++++++++++++---
 elf/Makefile              |  3 +++
 elf/dynamic-notes.c       |  4 ++++
 extra-lib.mk              |  3 +++
 htl/Makefile              |  3 +++
 iconvdata/Makefile        |  3 +++
 iconvdata/extra-module.mk |  4 ++++
 11 files changed, 106 insertions(+), 7 deletions(-)

diff --git a/Makeconfig b/Makeconfig
index 68663d984e..1046ebb291 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -398,6 +398,9 @@ LDFLAGS-lib.so += -Wl,-z,now
 # Extra flags for dynamically linked non-test main programs.
 link-extra-flags += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS-lib.so += -Wl,-z,unique
+endif
 
 # Command to run after every final link (executable or shared object).
 # This is invoked with $(call after-link,...), so it should operate on
diff --git a/Makerules b/Makerules
index 596fa68376..66c1251754 100644
--- a/Makerules
+++ b/Makerules
@@ -581,7 +581,8 @@ $(common-objpfx)shlib.lds: $(common-objpfx)config.make $(..)Makerules
 		 PROVIDE(__start___libc_IO_vtables = .);\
 		 __libc_IO_vtables : { *(__libc_IO_vtables) }\
 		 PROVIDE(__stop___libc_IO_vtables = .);\
-		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@'
+		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@' \
+	      -e 's/^.*\*(\.dynamic).*$$/   .dynamic : { *dynamic-notes.os(.dynamic) *(.dynamic) }/'
 	test -s $@T
 	mv -f $@T $@
 common-generated += shlib.lds
@@ -636,6 +637,16 @@ build-shlib-objlist = $(build-module-helper-objlist) \
 # Also omits crti.o and crtn.o, which we do not want
 # since we define our own `.init' section specially.
 LDFLAGS-c.so = -nostdlib -nostartfiles
+
+# The stub dynamic-notes.os should not have weak/undefined symbol magic in it.
+# It's not really part of the internals, rather it is a vector for linker magic
+# which we need when the linker isn't new enough:
+%/dynamic-notes.os: CPPFLAGS += -UMODULE_NAME
+
+ifeq ($(ld-zunique),yes)
+LDFLAGS-c.so += -Wl,-z,unique
+endif
+
 # But we still want to link libc.so against $(libc.so-gnulib).
 LDLIBS-c.so += $(libc.so-gnulib)
 # Give libc.so an entry point and make it directly runnable itself.
@@ -706,6 +717,11 @@ $(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \
 	$(build-shlib)
 	$(call after-link,$@)
 
+ifneq ($(ld-zunique),yes)
+$(common-objpfx)libc.so: $(common-objpfx)elf/dynamic-notes.os
+$(common-objpfx)linkobj/libc.so: $(common-objpfx)elf/dynamic-notes.os
+endif
+
 ifeq ($(build-shared),yes)
 $(common-objpfx)libc.so: $(common-objpfx)libc.map
 endif
diff --git a/config.make.in b/config.make.in
index cbf59114b0..8755490c13 100644
--- a/config.make.in
+++ b/config.make.in
@@ -72,6 +72,7 @@ have-cc-with-libunwind = @libc_cv_cc_with_libunwind@
 fno-unit-at-a-time = @fno_unit_at_a_time@
 bind-now = @bindnow@
 have-hash-style = @libc_cv_hashstyle@
+ld-zunique = @ld_zunique@
 use-default-link = @use_default_link@
 have-cxx-thread_local = @libc_cv_cxx_thread_local@
 have-loop-to-function = @libc_cv_cc_loop_to_function@
diff --git a/configure b/configure
index 9619c10991..3e6d7ffc49 100755
--- a/configure
+++ b/configure
@@ -625,6 +625,7 @@ libc_cv_cc_nofma
 libc_cv_mtls_dialect_gnu2
 fno_unit_at_a_time
 libc_cv_has_glob_dat
+ld_zunique
 libc_cv_hashstyle
 libc_cv_fpie
 libc_cv_z_execstack
@@ -6074,9 +6075,44 @@ fi
 $as_echo "$libc_cv_hashstyle" >&6; }
 
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support" >&5
+$as_echo_n "checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support... " >&6; }
+if { as_var=cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext; eval \${$as_var+:} false; }; then :
+  $as_echo_n "(cached) " >&6
+fi
+eval ac_res=\$cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+LDFLAGS="$old_LDFLAGS"
+
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sufficient default -shared layout" >&5
 $as_echo_n "checking for sufficient default -shared layout... " >&6; }
@@ -6119,10 +6155,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&5 "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&5 "\
 $libc_seen_a$libc_seen_b from:
diff --git a/configure.ac b/configure.ac
index 34ecbba540..6a443007fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1372,9 +1372,20 @@ fi
 rm -f conftest*])
 AC_SUBST(libc_cv_hashstyle)
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+AC_CACHE_CHECK([for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support],
+	       AC_LINK_IFELSE([AC_LANG_SOURCE([void foo (void) { }])],
+			      libc_cv_ld_zunique=yes,
+			      libc_cv_ld_zunique=no))
+LDFLAGS="$old_LDFLAGS"
+AC_SUBST(ld_zunique)
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   AC_CACHE_CHECK([for sufficient default -shared layout],
 		  libc_cv_use_default_link, [dnl
@@ -1410,10 +1421,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&AS_MESSAGE_LOG_FD "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&AS_MESSAGE_LOG_FD "\
 $libc_seen_a$libc_seen_b from:
diff --git a/elf/Makefile b/elf/Makefile
index d05f410592..f33a761c93 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -103,6 +103,9 @@ endif
 
 ifeq (yes,$(build-shared))
 extra-objs	= $(all-rtld-routines:%=%.os) sofini.os interp.os
+ifneq (yes,$(ld-zunique))
+extra-objs      += dynamic-notes.os
+endif
 generated	+= librtld.os dl-allobjs.os ld.so ldd
 install-others	= $(inst_rtlddir)/$(rtld-installed-name)
 install-bin-script = ldd
diff --git a/elf/dynamic-notes.c b/elf/dynamic-notes.c
new file mode 100644
index 0000000000..d0b487e970
--- /dev/null
+++ b/elf/dynamic-notes.c
@@ -0,0 +1,4 @@
+#include <link.h>
+
+const ElfW(Dyn) __dynamic_note __attribute__ ((section (".dynamic"))) =
+  { .d_tag = DT_GNU_FLAGS_1, .d_un.d_val = DF_GNU_1_UNIQUE };
diff --git a/extra-lib.mk b/extra-lib.mk
index 72f8d2e1df..9051958ec0 100644
--- a/extra-lib.mk
+++ b/extra-lib.mk
@@ -101,6 +101,9 @@ $(objpfx)$(lib).so: $(firstword $($(lib)-map) \
 				$(addprefix $(common-objpfx), \
 					    $(filter $(lib).map, \
 						     $(version-maps))))
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(lib).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
 endif
 
 endif
diff --git a/htl/Makefile b/htl/Makefile
index cf9d12fc12..c2a25dcd79 100644
--- a/htl/Makefile
+++ b/htl/Makefile
@@ -203,6 +203,9 @@ libc-link.so = $(common-objpfx)libc.so
 
 extra-B-pthread.so = -B$(common-objpfx)htl/
 LDFLAGS-pthread.so = -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst
+ifeq ($(ld-zunique),yes)
+LDFLAGS-pthread.so += -Wl,-z,unique
+endif
 
 include ../Rules
 
diff --git a/iconvdata/Makefile b/iconvdata/Makefile
index c216f959df..b1b46e5a43 100644
--- a/iconvdata/Makefile
+++ b/iconvdata/Makefile
@@ -67,6 +67,9 @@ modules	:= ISO8859-1 ISO8859-2 ISO8859-3 ISO8859-4 ISO8859-5		 \
 ifeq ($(bind-now),yes)
 LDFLAGS.so += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS.so += -Wl,-z,unique
+endif
 
 modules.so := $(addsuffix .so, $(modules))
 
diff --git a/iconvdata/extra-module.mk b/iconvdata/extra-module.mk
index ecaf507624..92c3ab4d7b 100644
--- a/iconvdata/extra-module.mk
+++ b/iconvdata/extra-module.mk
@@ -7,6 +7,10 @@ $(objpfx)$(mod).so: $(addprefix $(objpfx),$(addsuffix .os,$($(mod)-routines)))\
 		    $(shlib-lds) $(link-libc-deps)
 	$(build-module-asneeded)
 
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(mod).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
+
 ifneq (,$(extra-modules-left))
 include extra-module.mk
 endif


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [glibc/azanella/rtld-shared] elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
@ 2021-08-09 20:26 Adhemerval Zanella
  0 siblings, 0 replies; 6+ messages in thread
From: Adhemerval Zanella @ 2021-08-09 20:26 UTC (permalink / raw)
  To: glibc-cvs

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=83dc194adfa8e5b0747947806409a4582369da24

commit 83dc194adfa8e5b0747947806409a4582369da24
Author: Vivek Das Mohapatra <vivek@collabora.com>
Date:   Thu Jul 8 17:32:51 2021 +0100

    elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745)
    
    libc.so, libpthread.so etc should have the new unique-dso-by-default
    flag set to allow dlmopen to work better (libc et al instance shared
    by default when DSOs dlmopened into a new namespace).
    
    Checked on x86_64-linux-gnu and i686-linux-gnu.
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 Makeconfig                |  3 +++
 Makerules                 | 18 +++++++++++++++++-
 config.make.in            |  1 +
 configure                 | 48 ++++++++++++++++++++++++++++++++++++++++++++---
 configure.ac              | 23 ++++++++++++++++++++---
 elf/Makefile              |  3 +++
 elf/dynamic-notes.c       |  4 ++++
 extra-lib.mk              |  3 +++
 htl/Makefile              |  3 +++
 iconvdata/Makefile        |  3 +++
 iconvdata/extra-module.mk |  4 ++++
 11 files changed, 106 insertions(+), 7 deletions(-)

diff --git a/Makeconfig b/Makeconfig
index 68663d984e..1046ebb291 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -398,6 +398,9 @@ LDFLAGS-lib.so += -Wl,-z,now
 # Extra flags for dynamically linked non-test main programs.
 link-extra-flags += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS-lib.so += -Wl,-z,unique
+endif
 
 # Command to run after every final link (executable or shared object).
 # This is invoked with $(call after-link,...), so it should operate on
diff --git a/Makerules b/Makerules
index 596fa68376..66c1251754 100644
--- a/Makerules
+++ b/Makerules
@@ -581,7 +581,8 @@ $(common-objpfx)shlib.lds: $(common-objpfx)config.make $(..)Makerules
 		 PROVIDE(__start___libc_IO_vtables = .);\
 		 __libc_IO_vtables : { *(__libc_IO_vtables) }\
 		 PROVIDE(__stop___libc_IO_vtables = .);\
-		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@'
+		 /DISCARD/ : { *(.gnu.glibc-stub.*) }@' \
+	      -e 's/^.*\*(\.dynamic).*$$/   .dynamic : { *dynamic-notes.os(.dynamic) *(.dynamic) }/'
 	test -s $@T
 	mv -f $@T $@
 common-generated += shlib.lds
@@ -636,6 +637,16 @@ build-shlib-objlist = $(build-module-helper-objlist) \
 # Also omits crti.o and crtn.o, which we do not want
 # since we define our own `.init' section specially.
 LDFLAGS-c.so = -nostdlib -nostartfiles
+
+# The stub dynamic-notes.os should not have weak/undefined symbol magic in it.
+# It's not really part of the internals, rather it is a vector for linker magic
+# which we need when the linker isn't new enough:
+%/dynamic-notes.os: CPPFLAGS += -UMODULE_NAME
+
+ifeq ($(ld-zunique),yes)
+LDFLAGS-c.so += -Wl,-z,unique
+endif
+
 # But we still want to link libc.so against $(libc.so-gnulib).
 LDLIBS-c.so += $(libc.so-gnulib)
 # Give libc.so an entry point and make it directly runnable itself.
@@ -706,6 +717,11 @@ $(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \
 	$(build-shlib)
 	$(call after-link,$@)
 
+ifneq ($(ld-zunique),yes)
+$(common-objpfx)libc.so: $(common-objpfx)elf/dynamic-notes.os
+$(common-objpfx)linkobj/libc.so: $(common-objpfx)elf/dynamic-notes.os
+endif
+
 ifeq ($(build-shared),yes)
 $(common-objpfx)libc.so: $(common-objpfx)libc.map
 endif
diff --git a/config.make.in b/config.make.in
index cbf59114b0..8755490c13 100644
--- a/config.make.in
+++ b/config.make.in
@@ -72,6 +72,7 @@ have-cc-with-libunwind = @libc_cv_cc_with_libunwind@
 fno-unit-at-a-time = @fno_unit_at_a_time@
 bind-now = @bindnow@
 have-hash-style = @libc_cv_hashstyle@
+ld-zunique = @ld_zunique@
 use-default-link = @use_default_link@
 have-cxx-thread_local = @libc_cv_cxx_thread_local@
 have-loop-to-function = @libc_cv_cc_loop_to_function@
diff --git a/configure b/configure
index 9619c10991..3e6d7ffc49 100755
--- a/configure
+++ b/configure
@@ -625,6 +625,7 @@ libc_cv_cc_nofma
 libc_cv_mtls_dialect_gnu2
 fno_unit_at_a_time
 libc_cv_has_glob_dat
+ld_zunique
 libc_cv_hashstyle
 libc_cv_fpie
 libc_cv_z_execstack
@@ -6074,9 +6075,44 @@ fi
 $as_echo "$libc_cv_hashstyle" >&6; }
 
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support" >&5
+$as_echo_n "checking for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support... " >&6; }
+if { as_var=cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext; eval \${$as_var+:} false; }; then :
+  $as_echo_n "(cached) " >&6
+fi
+eval ac_res=\$cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+void foo (void) { }
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  libc_cv_ld_zunique=yes
+else
+  libc_cv_ld_zunique=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+	       { $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_res" >&5
+$as_echo "$ac_res" >&6; }
+LDFLAGS="$old_LDFLAGS"
+
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for sufficient default -shared layout" >&5
 $as_echo_n "checking for sufficient default -shared layout... " >&6; }
@@ -6119,10 +6155,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&5 "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&5 "\
 $libc_seen_a$libc_seen_b from:
diff --git a/configure.ac b/configure.ac
index 34ecbba540..6a443007fe 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1372,9 +1372,20 @@ fi
 rm -f conftest*])
 AC_SUBST(libc_cv_hashstyle)
 
+old_LDFLAGS="$LDFLAGS"
+LDFLAGS="-Wl,--fatal-warnings -Wl,-z,unique -shared"
+AC_CACHE_CHECK([for linker DT_GNU_FLAGS_1 / DF_GNU_1_UNIQUE support],
+	       AC_LINK_IFELSE([AC_LANG_SOURCE([void foo (void) { }])],
+			      libc_cv_ld_zunique=yes,
+			      libc_cv_ld_zunique=no))
+LDFLAGS="$old_LDFLAGS"
+AC_SUBST(ld_zunique)
+
 # The linker's default -shared behavior is good enough if it
 # does these things that our custom linker scripts ensure that
-# all allocated NOTE sections come first.
+# all allocated NOTE sections come first AND it understands
+# -z unique should result in DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE
+# sections in its output.
 if test "$use_default_link" = default; then
   AC_CACHE_CHECK([for sufficient default -shared layout],
 		  libc_cv_use_default_link, [dnl
@@ -1410,10 +1421,16 @@ EOF
       esac
       shift 2
     done
-    case "$libc_seen_a$libc_seen_b" in
-    yesyes)
+    case "$libc_seen_a$libc_seen_b$libc_cv_ld_zunique" in
+    yesyesyes)
       libc_cv_use_default_link=yes
       ;;
+    yesyesno)
+      echo >&AS_MESSAGE_LOG_FD "\
+shared layout from:
+$ac_try
+is OK but -Wl,-z,unique is unsupported so linker scripts are required"
+      ;;
     *)
       echo >&AS_MESSAGE_LOG_FD "\
 $libc_seen_a$libc_seen_b from:
diff --git a/elf/Makefile b/elf/Makefile
index d05f410592..f33a761c93 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -103,6 +103,9 @@ endif
 
 ifeq (yes,$(build-shared))
 extra-objs	= $(all-rtld-routines:%=%.os) sofini.os interp.os
+ifneq (yes,$(ld-zunique))
+extra-objs      += dynamic-notes.os
+endif
 generated	+= librtld.os dl-allobjs.os ld.so ldd
 install-others	= $(inst_rtlddir)/$(rtld-installed-name)
 install-bin-script = ldd
diff --git a/elf/dynamic-notes.c b/elf/dynamic-notes.c
new file mode 100644
index 0000000000..d0b487e970
--- /dev/null
+++ b/elf/dynamic-notes.c
@@ -0,0 +1,4 @@
+#include <link.h>
+
+const ElfW(Dyn) __dynamic_note __attribute__ ((section (".dynamic"))) =
+  { .d_tag = DT_GNU_FLAGS_1, .d_un.d_val = DF_GNU_1_UNIQUE };
diff --git a/extra-lib.mk b/extra-lib.mk
index 72f8d2e1df..9051958ec0 100644
--- a/extra-lib.mk
+++ b/extra-lib.mk
@@ -101,6 +101,9 @@ $(objpfx)$(lib).so: $(firstword $($(lib)-map) \
 				$(addprefix $(common-objpfx), \
 					    $(filter $(lib).map, \
 						     $(version-maps))))
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(lib).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
 endif
 
 endif
diff --git a/htl/Makefile b/htl/Makefile
index cf9d12fc12..c2a25dcd79 100644
--- a/htl/Makefile
+++ b/htl/Makefile
@@ -203,6 +203,9 @@ libc-link.so = $(common-objpfx)libc.so
 
 extra-B-pthread.so = -B$(common-objpfx)htl/
 LDFLAGS-pthread.so = -Wl,--enable-new-dtags,-z,nodelete,-z,initfirst
+ifeq ($(ld-zunique),yes)
+LDFLAGS-pthread.so += -Wl,-z,unique
+endif
 
 include ../Rules
 
diff --git a/iconvdata/Makefile b/iconvdata/Makefile
index c216f959df..b1b46e5a43 100644
--- a/iconvdata/Makefile
+++ b/iconvdata/Makefile
@@ -67,6 +67,9 @@ modules	:= ISO8859-1 ISO8859-2 ISO8859-3 ISO8859-4 ISO8859-5		 \
 ifeq ($(bind-now),yes)
 LDFLAGS.so += -Wl,-z,now
 endif
+ifeq ($(ld-zunique),yes)
+LDFLAGS.so += -Wl,-z,unique
+endif
 
 modules.so := $(addsuffix .so, $(modules))
 
diff --git a/iconvdata/extra-module.mk b/iconvdata/extra-module.mk
index ecaf507624..92c3ab4d7b 100644
--- a/iconvdata/extra-module.mk
+++ b/iconvdata/extra-module.mk
@@ -7,6 +7,10 @@ $(objpfx)$(mod).so: $(addprefix $(objpfx),$(addsuffix .os,$($(mod)-routines)))\
 		    $(shlib-lds) $(link-libc-deps)
 	$(build-module-asneeded)
 
+ifneq ($(ld-zunique),yes)
+$(objpfx)$(mod).so: $(common-objpfx)/elf/dynamic-notes.os
+endif
+
 ifneq (,$(extra-modules-left))
 include extra-module.mk
 endif


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2021-09-27 18:54 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-09 20:17 [glibc/azanella/rtld-shared] elf: Add DT_GNU_FLAGS_1/DF_GNU_1_UNIQUE to glibc DSOs (BZ #22745) Adhemerval Zanella
2021-08-09 20:26 Adhemerval Zanella
2021-08-09 20:31 Adhemerval Zanella
2021-08-10 12:43 Adhemerval Zanella
2021-08-10 13:42 Adhemerval Zanella
2021-09-27 18:54 Adhemerval Zanella

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