Message ID | 20210331193923.2602174-1-maskray@google.com |
---|---|
State | New |
Headers | show |
Series | [v4] Set the retain attribute on _elf_set_element if CC supports [BZ #27492] | expand |
On Wed, Mar 31, 2021 at 12:39 PM Fangrui Song <maskray@google.com> wrote: > > So that text_set_element/data_set_element/bss_set_element defined > variables will be retained by the linker. > > Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > will not be optimized out; 'retain' prevents section garbage collection > if the linker support SHF_GNU_RETAIN. > > GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > identifier name sections to be GCed even if there are live > __start_/__stop_ references. > > Without the change, there are some static linking problems, e.g. > _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > stdout is not flushed on exit. > > Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > --- > Changes in v1 -> v2: > * Define attribute_used_retain_section > Changes in v2 -> v3: > * Use attribute_used_retain instead attribute_used_retain_section > Changes in v3 -> v4: > * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > --- > config.h.in | 3 +++ > configure | 58 ++++++++++++++++++++++++++++++++++++++++++ > configure.ac | 20 +++++++++++++++ > include/libc-symbols.h | 14 +++++++--- > libio/Makefile | 32 +++++++++++++++++++++++ > libio/tst-cleanup.c | 33 ++++++++++++++++++++++++ > libio/tst-cleanup.exp | 1 + > 7 files changed, 157 insertions(+), 4 deletions(-) > create mode 100644 libio/tst-cleanup.c > create mode 100644 libio/tst-cleanup.exp > > diff --git a/config.h.in b/config.h.in > index ca1547ae67..95af1ef229 100644 > --- a/config.h.in > +++ b/config.h.in > @@ -187,6 +187,9 @@ > /* Define if gcc supports attribute ifunc. */ > #undef HAVE_GCC_IFUNC > > +/* Define if gcc supports attribute retain. */ > +#undef HAVE_GCC_RETAIN > + > /* Define if the linker defines __ehdr_start. */ > #undef HAVE_EHDR_START > > diff --git a/configure b/configure > index fcf43bf7de..fa86348342 100755 > --- a/configure > +++ b/configure > @@ -626,6 +626,7 @@ fno_unit_at_a_time > libc_cv_has_glob_dat > libc_cv_hashstyle > libc_cv_fpie > +libc_cv_z_start_stop_gc > libc_cv_z_execstack > libc_cv_z_combreloc > ASFLAGS_config > @@ -4105,6 +4106,29 @@ fi > $as_echo "$libc_cv_textrel_ifunc" >&6; } > > > +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > +$as_echo_n "checking for gcc attribute retain support... " >&6; } > +if ${libc_cv_gcc_retain+:} false; then : > + $as_echo_n "(cached) " >&6 > +else > + cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gcc_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > + 2>&5 ; then > + libc_cv_gcc_retain=yes > +fi > +rm -f conftest* > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > +$as_echo "$libc_cv_gcc_retain" >&6; } > +if test $libc_cv_gcc_retain = yes; then > + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > + > +fi > + > # Check if gcc warns about alias for function with incompatible types. > { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > @@ -5871,6 +5895,40 @@ fi > $as_echo "$libc_linker_feature" >&6; } > > > +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > +libc_linker_feature=no > +if test x"$gnu_ld" = x"yes"; then > + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > + if test -n "$libc_linker_check"; then > + cat > conftest.c <<EOF > +int _start (void) { return 42; } > +EOF > + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > + -fPIC -shared -o conftest.so conftest.c > + 1>&5' > + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > + (eval $ac_try) 2>&5 > + ac_status=$? > + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > + test $ac_status = 0; }; } > + then > + libc_linker_feature=yes > + fi > + rm -f conftest* > + fi > +fi > +if test $libc_linker_feature = yes; then > + libc_cv_z_start_stop_gc=yes > +else > + libc_cv_z_start_stop_gc=no > +fi > +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > +$as_echo "$libc_linker_feature" >&6; } > +config_vars="$config_vars > +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > + > { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > libc_linker_feature=no > diff --git a/configure.ac b/configure.ac > index fce967f2c2..4e2907da92 100644 > --- a/configure.ac > +++ b/configure.ac > @@ -707,6 +707,22 @@ fi > rm -f conftest*]) > AC_SUBST(libc_cv_textrel_ifunc) > > +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. > +AC_CACHE_CHECK([for gcc attribute retain support], > + libc_cv_gcc_retain, [dnl > +cat > conftest.c <<EOF > +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > +EOF > +libc_cv_gcc_retain=no > +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > + 2>&AS_MESSAGE_LOG_FD ; then > + libc_cv_gcc_retain=yes > +fi > +rm -f conftest*]) > +if test $libc_cv_gcc_retain = yes; then > + AC_DEFINE(HAVE_GCC_RETAIN) > +fi > + > # Check if gcc warns about alias for function with incompatible types. > AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > libc_cv_gcc_incompatible_alias, [dnl > @@ -1317,6 +1333,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > AC_SUBST(libc_cv_z_execstack) > > +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > + > LIBC_LINKER_FEATURE([--no-dynamic-linker], > [-Wl,--no-dynamic-linker], > [libc_cv_no_dynamic_linker=yes], > diff --git a/include/libc-symbols.h b/include/libc-symbols.h > index 546fc26a7b..b311c90f0c 100644 > --- a/include/libc-symbols.h > +++ b/include/libc-symbols.h > @@ -352,6 +352,12 @@ for linking") > > */ > > +#ifdef HAVE_GCC_RETAIN > +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > +#else > +# define attribute_used_retain __attribute__ ((__used__)) > +#endif > + > /* Symbol set support macros. */ > > /* Make SYMBOL, which is in the text segment, an element of SET. */ > @@ -367,12 +373,12 @@ for linking") > /* When building a shared library, make the set section writable, > because it will need to be relocated at run time anyway. */ > # define _elf_set_element(set, symbol) \ > - static const void *__elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *__elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #else > # define _elf_set_element(set, symbol) \ > - static const void *const __elf_set_##set##_element_##symbol##__ \ > - __attribute__ ((used, section (#set))) = &(symbol) > + static const void *const __elf_set_##set##_element_##symbol##__ \ > + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > #endif > > /* Define SET as a symbol set. This may be required (it is in a.out) to > diff --git a/libio/Makefile b/libio/Makefile > index 12ce41038f..439d22e057 100644 > --- a/libio/Makefile > +++ b/libio/Makefile > @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > $(objpfx)tst-bz24228-mem.out > endif > + > +tests += tst-cleanup-default > +tests-static += tst-cleanup-default > +tests-special += $(objpfx)tst-cleanup-default-cmp.out > +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > + > +ifeq ($(have-z-start-stop-gc),yes) > +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc Won't this test fail if linker supports -z start-stop-gc and GCC doesn't support retain attribute? > +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc > +endif > endif > > include ../Rules > @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) > $(objpfx)tst-wfile-sync.out: $(gen-locales) > endif > > +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-default.o: tst-cleanup.c > + $(compile.c) -o $@ > + > +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > + > +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out > + cmp $^ > $@; \ > + $(evaluate-test) > +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c > + $(compile.c) -o $@ > + > $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen > $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ > $(common-objpfx)libio/; \ > diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c > new file mode 100644 > index 0000000000..7f0a34a91e > --- /dev/null > +++ b/libio/tst-cleanup.c > @@ -0,0 +1,33 @@ > +/* Copyright (C) 2021 Free Software Foundation, Inc. > + This file is part of the GNU C Library. > + > + The GNU C Library is free software; you can redistribute it and/or > + modify it under the terms of the GNU Lesser General Public > + License as published by the Free Software Foundation; either > + version 2.1 of the License, or (at your option) any later version. > + > + The GNU C Library is distributed in the hope that it will be useful, > + but WITHOUT ANY WARRANTY; without even the implied warranty of > + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU > + Lesser General Public License for more details. > + > + You should have received a copy of the GNU Lesser General Public > + License along with the GNU C Library; if not, see > + <https://www.gnu.org/licenses/>. */ > + > +/* Test that stdout is flushed after atexit callbacks were run. */ > + > +#include <stdio.h> > +#include <stdlib.h> > + > +void > +hook (void) > +{ > + puts ("hello"); > +} > + > +int > +main (void) > +{ > + atexit (hook); > +} > diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp > new file mode 100644 > index 0000000000..ce01362503 > --- /dev/null > +++ b/libio/tst-cleanup.exp > @@ -0,0 +1 @@ > +hello > -- > 2.31.0.291.g576ba9dcdaf-goog >
On 2021-03-31, H.J. Lu wrote: >On Wed, Mar 31, 2021 at 12:39 PM Fangrui Song <maskray@google.com> wrote: >> >> So that text_set_element/data_set_element/bss_set_element defined >> variables will be retained by the linker. >> >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable >> will not be optimized out; 'retain' prevents section garbage collection >> if the linker support SHF_GNU_RETAIN. >> >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C >> identifier name sections to be GCed even if there are live >> __start_/__stop_ references. >> >> Without the change, there are some static linking problems, e.g. >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so >> stdout is not flushed on exit. >> >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). >> --- >> Changes in v1 -> v2: >> * Define attribute_used_retain_section >> Changes in v2 -> v3: >> * Use attribute_used_retain instead attribute_used_retain_section >> Changes in v3 -> v4: >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests >> --- >> config.h.in | 3 +++ >> configure | 58 ++++++++++++++++++++++++++++++++++++++++++ >> configure.ac | 20 +++++++++++++++ >> include/libc-symbols.h | 14 +++++++--- >> libio/Makefile | 32 +++++++++++++++++++++++ >> libio/tst-cleanup.c | 33 ++++++++++++++++++++++++ >> libio/tst-cleanup.exp | 1 + >> 7 files changed, 157 insertions(+), 4 deletions(-) >> create mode 100644 libio/tst-cleanup.c >> create mode 100644 libio/tst-cleanup.exp >> >> diff --git a/config.h.in b/config.h.in >> index ca1547ae67..95af1ef229 100644 >> --- a/config.h.in >> +++ b/config.h.in >> @@ -187,6 +187,9 @@ >> /* Define if gcc supports attribute ifunc. */ >> #undef HAVE_GCC_IFUNC >> >> +/* Define if gcc supports attribute retain. */ >> +#undef HAVE_GCC_RETAIN >> + >> /* Define if the linker defines __ehdr_start. */ >> #undef HAVE_EHDR_START >> >> diff --git a/configure b/configure >> index fcf43bf7de..fa86348342 100755 >> --- a/configure >> +++ b/configure >> @@ -626,6 +626,7 @@ fno_unit_at_a_time >> libc_cv_has_glob_dat >> libc_cv_hashstyle >> libc_cv_fpie >> +libc_cv_z_start_stop_gc >> libc_cv_z_execstack >> libc_cv_z_combreloc >> ASFLAGS_config >> @@ -4105,6 +4106,29 @@ fi >> $as_echo "$libc_cv_textrel_ifunc" >&6; } >> >> >> +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 >> +$as_echo_n "checking for gcc attribute retain support... " >&6; } >> +if ${libc_cv_gcc_retain+:} false; then : >> + $as_echo_n "(cached) " >&6 >> +else >> + cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gcc_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ >> + 2>&5 ; then >> + libc_cv_gcc_retain=yes >> +fi >> +rm -f conftest* >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 >> +$as_echo "$libc_cv_gcc_retain" >&6; } >> +if test $libc_cv_gcc_retain = yes; then >> + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h >> + >> +fi >> + >> # Check if gcc warns about alias for function with incompatible types. >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } >> @@ -5871,6 +5895,40 @@ fi >> $as_echo "$libc_linker_feature" >&6; } >> >> >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } >> +libc_linker_feature=no >> +if test x"$gnu_ld" = x"yes"; then >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` >> + if test -n "$libc_linker_check"; then >> + cat > conftest.c <<EOF >> +int _start (void) { return 42; } >> +EOF >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles >> + -fPIC -shared -o conftest.so conftest.c >> + 1>&5' >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 >> + (eval $ac_try) 2>&5 >> + ac_status=$? >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 >> + test $ac_status = 0; }; } >> + then >> + libc_linker_feature=yes >> + fi >> + rm -f conftest* >> + fi >> +fi >> +if test $libc_linker_feature = yes; then >> + libc_cv_z_start_stop_gc=yes >> +else >> + libc_cv_z_start_stop_gc=no >> +fi >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 >> +$as_echo "$libc_linker_feature" >&6; } >> +config_vars="$config_vars >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" >> + >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } >> libc_linker_feature=no >> diff --git a/configure.ac b/configure.ac >> index fce967f2c2..4e2907da92 100644 >> --- a/configure.ac >> +++ b/configure.ac >> @@ -707,6 +707,22 @@ fi >> rm -f conftest*]) >> AC_SUBST(libc_cv_textrel_ifunc) >> >> +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. >> +AC_CACHE_CHECK([for gcc attribute retain support], >> + libc_cv_gcc_retain, [dnl >> +cat > conftest.c <<EOF >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); >> +EOF >> +libc_cv_gcc_retain=no >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ >> + 2>&AS_MESSAGE_LOG_FD ; then >> + libc_cv_gcc_retain=yes >> +fi >> +rm -f conftest*]) >> +if test $libc_cv_gcc_retain = yes; then >> + AC_DEFINE(HAVE_GCC_RETAIN) >> +fi >> + >> # Check if gcc warns about alias for function with incompatible types. >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], >> libc_cv_gcc_incompatible_alias, [dnl >> @@ -1317,6 +1333,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) >> AC_SUBST(libc_cv_z_execstack) >> >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) >> + >> LIBC_LINKER_FEATURE([--no-dynamic-linker], >> [-Wl,--no-dynamic-linker], >> [libc_cv_no_dynamic_linker=yes], >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h >> index 546fc26a7b..b311c90f0c 100644 >> --- a/include/libc-symbols.h >> +++ b/include/libc-symbols.h >> @@ -352,6 +352,12 @@ for linking") >> >> */ >> >> +#ifdef HAVE_GCC_RETAIN >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) >> +#else >> +# define attribute_used_retain __attribute__ ((__used__)) >> +#endif >> + >> /* Symbol set support macros. */ >> >> /* Make SYMBOL, which is in the text segment, an element of SET. */ >> @@ -367,12 +373,12 @@ for linking") >> /* When building a shared library, make the set section writable, >> because it will need to be relocated at run time anyway. */ >> # define _elf_set_element(set, symbol) \ >> - static const void *__elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *__elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #else >> # define _elf_set_element(set, symbol) \ >> - static const void *const __elf_set_##set##_element_##symbol##__ \ >> - __attribute__ ((used, section (#set))) = &(symbol) >> + static const void *const __elf_set_##set##_element_##symbol##__ \ >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) >> #endif >> >> /* Define SET as a symbol set. This may be required (it is in a.out) to >> diff --git a/libio/Makefile b/libio/Makefile >> index 12ce41038f..439d22e057 100644 >> --- a/libio/Makefile >> +++ b/libio/Makefile >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ >> $(objpfx)tst-bz24228-mem.out >> endif >> + >> +tests += tst-cleanup-default >> +tests-static += tst-cleanup-default >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections >> + >> +ifeq ($(have-z-start-stop-gc),yes) >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > >Won't this test fail if linker supports -z start-stop-gc and GCC doesn't support >retain attribute? Yes, but that doesn't happen in practice. If ld supports -z start-stop-gc, the GNU as should be new and the GCC should support 'retain'. But perhaps it is good to prevent the issue, I can change +ifeq ($(have-z-start-stop-gc),yes) to +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) and add a LIBC_CONFIG_VAR in configure.ac. >> +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc >> +endif >> endif >> >> include ../Rules >> @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) >> $(objpfx)tst-wfile-sync.out: $(gen-locales) >> endif >> >> +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-default.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out >> + cmp $^ > $@; \ >> + $(evaluate-test) >> +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c >> + $(compile.c) -o $@ >> + >> $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen >> $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ >> $(common-objpfx)libio/; \ >> diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c >> new file mode 100644 >> index 0000000000..7f0a34a91e >> --- /dev/null >> +++ b/libio/tst-cleanup.c >> @@ -0,0 +1,33 @@ >> +/* Copyright (C) 2021 Free Software Foundation, Inc. >> + This file is part of the GNU C Library. >> + >> + The GNU C Library is free software; you can redistribute it and/or >> + modify it under the terms of the GNU Lesser General Public >> + License as published by the Free Software Foundation; either >> + version 2.1 of the License, or (at your option) any later version. >> + >> + The GNU C Library is distributed in the hope that it will be useful, >> + but WITHOUT ANY WARRANTY; without even the implied warranty of >> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU >> + Lesser General Public License for more details. >> + >> + You should have received a copy of the GNU Lesser General Public >> + License along with the GNU C Library; if not, see >> + <https://www.gnu.org/licenses/>. */ >> + >> +/* Test that stdout is flushed after atexit callbacks were run. */ >> + >> +#include <stdio.h> >> +#include <stdlib.h> >> + >> +void >> +hook (void) >> +{ >> + puts ("hello"); >> +} >> + >> +int >> +main (void) >> +{ >> + atexit (hook); >> +} >> diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp >> new file mode 100644 >> index 0000000000..ce01362503 >> --- /dev/null >> +++ b/libio/tst-cleanup.exp >> @@ -0,0 +1 @@ >> +hello >> -- >> 2.31.0.291.g576ba9dcdaf-goog >> > > >-- >H.J.
On Wed, Mar 31, 2021 at 5:02 PM Fangrui Song <maskray@google.com> wrote: > > On 2021-03-31, H.J. Lu wrote: > >On Wed, Mar 31, 2021 at 12:39 PM Fangrui Song <maskray@google.com> wrote: > >> > >> So that text_set_element/data_set_element/bss_set_element defined > >> variables will be retained by the linker. > >> > >> Note: 'used' and 'retain' are orthogonal: 'used' makes sure the variable > >> will not be optimized out; 'retain' prevents section garbage collection > >> if the linker support SHF_GNU_RETAIN. > >> > >> GNU ld 2.37 and LLD 13 will support -z start-stop-gc which allow C > >> identifier name sections to be GCed even if there are live > >> __start_/__stop_ references. > >> > >> Without the change, there are some static linking problems, e.g. > >> _IO_cleanup (libio/genops.c) may be discarded by ld --gc-sections, so > >> stdout is not flushed on exit. > >> > >> Note: GCC may warning ‘retain’ attribute ignored while __has_attribute(retain) is 1 > >> (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99587). > >> --- > >> Changes in v1 -> v2: > >> * Define attribute_used_retain_section > >> Changes in v2 -> v3: > >> * Use attribute_used_retain instead attribute_used_retain_section > >> Changes in v3 -> v4: > >> * Add LIBC_LINKER_FEATURE detection for -z start-stop-gc and add tst-cleanup* tests > >> --- > >> config.h.in | 3 +++ > >> configure | 58 ++++++++++++++++++++++++++++++++++++++++++ > >> configure.ac | 20 +++++++++++++++ > >> include/libc-symbols.h | 14 +++++++--- > >> libio/Makefile | 32 +++++++++++++++++++++++ > >> libio/tst-cleanup.c | 33 ++++++++++++++++++++++++ > >> libio/tst-cleanup.exp | 1 + > >> 7 files changed, 157 insertions(+), 4 deletions(-) > >> create mode 100644 libio/tst-cleanup.c > >> create mode 100644 libio/tst-cleanup.exp > >> > >> diff --git a/config.h.in b/config.h.in > >> index ca1547ae67..95af1ef229 100644 > >> --- a/config.h.in > >> +++ b/config.h.in > >> @@ -187,6 +187,9 @@ > >> /* Define if gcc supports attribute ifunc. */ > >> #undef HAVE_GCC_IFUNC > >> > >> +/* Define if gcc supports attribute retain. */ > >> +#undef HAVE_GCC_RETAIN > >> + > >> /* Define if the linker defines __ehdr_start. */ > >> #undef HAVE_EHDR_START > >> > >> diff --git a/configure b/configure > >> index fcf43bf7de..fa86348342 100755 > >> --- a/configure > >> +++ b/configure > >> @@ -626,6 +626,7 @@ fno_unit_at_a_time > >> libc_cv_has_glob_dat > >> libc_cv_hashstyle > >> libc_cv_fpie > >> +libc_cv_z_start_stop_gc > >> libc_cv_z_execstack > >> libc_cv_z_combreloc > >> ASFLAGS_config > >> @@ -4105,6 +4106,29 @@ fi > >> $as_echo "$libc_cv_textrel_ifunc" >&6; } > >> > >> > >> +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 > >> +$as_echo_n "checking for gcc attribute retain support... " >&6; } > >> +if ${libc_cv_gcc_retain+:} false; then : > >> + $as_echo_n "(cached) " >&6 > >> +else > >> + cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gcc_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ > >> + 2>&5 ; then > >> + libc_cv_gcc_retain=yes > >> +fi > >> +rm -f conftest* > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 > >> +$as_echo "$libc_cv_gcc_retain" >&6; } > >> +if test $libc_cv_gcc_retain = yes; then > >> + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h > >> + > >> +fi > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 > >> $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } > >> @@ -5871,6 +5895,40 @@ fi > >> $as_echo "$libc_linker_feature" >&6; } > >> > >> > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 > >> +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } > >> +libc_linker_feature=no > >> +if test x"$gnu_ld" = x"yes"; then > >> + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` > >> + if test -n "$libc_linker_check"; then > >> + cat > conftest.c <<EOF > >> +int _start (void) { return 42; } > >> +EOF > >> + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp > >> + -Wl,-z,start-stop-gc -nostdlib -nostartfiles > >> + -fPIC -shared -o conftest.so conftest.c > >> + 1>&5' > >> + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 > >> + (eval $ac_try) 2>&5 > >> + ac_status=$? > >> + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 > >> + test $ac_status = 0; }; } > >> + then > >> + libc_linker_feature=yes > >> + fi > >> + rm -f conftest* > >> + fi > >> +fi > >> +if test $libc_linker_feature = yes; then > >> + libc_cv_z_start_stop_gc=yes > >> +else > >> + libc_cv_z_start_stop_gc=no > >> +fi > >> +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 > >> +$as_echo "$libc_linker_feature" >&6; } > >> +config_vars="$config_vars > >> +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" > >> + > >> { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 > >> $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } > >> libc_linker_feature=no > >> diff --git a/configure.ac b/configure.ac > >> index fce967f2c2..4e2907da92 100644 > >> --- a/configure.ac > >> +++ b/configure.ac > >> @@ -707,6 +707,22 @@ fi > >> rm -f conftest*]) > >> AC_SUBST(libc_cv_textrel_ifunc) > >> > >> +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. > >> +AC_CACHE_CHECK([for gcc attribute retain support], > >> + libc_cv_gcc_retain, [dnl > >> +cat > conftest.c <<EOF > >> +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); > >> +EOF > >> +libc_cv_gcc_retain=no > >> +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ > >> + 2>&AS_MESSAGE_LOG_FD ; then > >> + libc_cv_gcc_retain=yes > >> +fi > >> +rm -f conftest*]) > >> +if test $libc_cv_gcc_retain = yes; then > >> + AC_DEFINE(HAVE_GCC_RETAIN) > >> +fi > >> + > >> # Check if gcc warns about alias for function with incompatible types. > >> AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], > >> libc_cv_gcc_incompatible_alias, [dnl > >> @@ -1317,6 +1333,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], > >> [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) > >> AC_SUBST(libc_cv_z_execstack) > >> > >> +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], > >> + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) > >> +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) > >> + > >> LIBC_LINKER_FEATURE([--no-dynamic-linker], > >> [-Wl,--no-dynamic-linker], > >> [libc_cv_no_dynamic_linker=yes], > >> diff --git a/include/libc-symbols.h b/include/libc-symbols.h > >> index 546fc26a7b..b311c90f0c 100644 > >> --- a/include/libc-symbols.h > >> +++ b/include/libc-symbols.h > >> @@ -352,6 +352,12 @@ for linking") > >> > >> */ > >> > >> +#ifdef HAVE_GCC_RETAIN > >> +# define attribute_used_retain __attribute__ ((__used__, __retain__)) > >> +#else > >> +# define attribute_used_retain __attribute__ ((__used__)) > >> +#endif > >> + > >> /* Symbol set support macros. */ > >> > >> /* Make SYMBOL, which is in the text segment, an element of SET. */ > >> @@ -367,12 +373,12 @@ for linking") > >> /* When building a shared library, make the set section writable, > >> because it will need to be relocated at run time anyway. */ > >> # define _elf_set_element(set, symbol) \ > >> - static const void *__elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *__elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #else > >> # define _elf_set_element(set, symbol) \ > >> - static const void *const __elf_set_##set##_element_##symbol##__ \ > >> - __attribute__ ((used, section (#set))) = &(symbol) > >> + static const void *const __elf_set_##set##_element_##symbol##__ \ > >> + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) > >> #endif > >> > >> /* Define SET as a symbol set. This may be required (it is in a.out) to > >> diff --git a/libio/Makefile b/libio/Makefile > >> index 12ce41038f..439d22e057 100644 > >> --- a/libio/Makefile > >> +++ b/libio/Makefile > >> @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) > >> tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ > >> $(objpfx)tst-bz24228-mem.out > >> endif > >> + > >> +tests += tst-cleanup-default > >> +tests-static += tst-cleanup-default > >> +tests-special += $(objpfx)tst-cleanup-default-cmp.out > >> +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections > >> + > >> +ifeq ($(have-z-start-stop-gc),yes) > >> +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc > >> +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ > >> + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out > >> +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc > > > >Won't this test fail if linker supports -z start-stop-gc and GCC doesn't support > >retain attribute? > > Yes, but that doesn't happen in practice. If ld supports -z start-stop-gc, > the GNU as should be new and the GCC should support 'retain'. I am using GCC 10 and binutils 2.37. > But perhaps it is good to prevent the issue, I can change > > +ifeq ($(have-z-start-stop-gc),yes) > > to > > +ifeq ($(have-gnu-retain)$(have-z-start-stop-gc),yesyes) > > and add a LIBC_CONFIG_VAR in configure.ac. > Yes, please. Thanks.
diff --git a/config.h.in b/config.h.in index ca1547ae67..95af1ef229 100644 --- a/config.h.in +++ b/config.h.in @@ -187,6 +187,9 @@ /* Define if gcc supports attribute ifunc. */ #undef HAVE_GCC_IFUNC +/* Define if gcc supports attribute retain. */ +#undef HAVE_GCC_RETAIN + /* Define if the linker defines __ehdr_start. */ #undef HAVE_EHDR_START diff --git a/configure b/configure index fcf43bf7de..fa86348342 100755 --- a/configure +++ b/configure @@ -626,6 +626,7 @@ fno_unit_at_a_time libc_cv_has_glob_dat libc_cv_hashstyle libc_cv_fpie +libc_cv_z_start_stop_gc libc_cv_z_execstack libc_cv_z_combreloc ASFLAGS_config @@ -4105,6 +4106,29 @@ fi $as_echo "$libc_cv_textrel_ifunc" >&6; } +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for gcc attribute retain support" >&5 +$as_echo_n "checking for gcc attribute retain support... " >&6; } +if ${libc_cv_gcc_retain+:} false; then : + $as_echo_n "(cached) " >&6 +else + cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gcc_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&5 \ + 2>&5 ; then + libc_cv_gcc_retain=yes +fi +rm -f conftest* +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_retain" >&5 +$as_echo "$libc_cv_gcc_retain" >&6; } +if test $libc_cv_gcc_retain = yes; then + $as_echo "#define HAVE_GCC_RETAIN 1" >>confdefs.h + +fi + # Check if gcc warns about alias for function with incompatible types. { $as_echo "$as_me:${as_lineno-$LINENO}: checking if compiler warns about alias for function with incompatible types" >&5 $as_echo_n "checking if compiler warns about alias for function with incompatible types... " >&6; } @@ -5871,6 +5895,40 @@ fi $as_echo "$libc_linker_feature" >&6; } +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports -z start-stop-gc" >&5 +$as_echo_n "checking for linker that supports -z start-stop-gc... " >&6; } +libc_linker_feature=no +if test x"$gnu_ld" = x"yes"; then + libc_linker_check=`$LD -v --help 2>/dev/null | grep "\-z start-stop-gc"` + if test -n "$libc_linker_check"; then + cat > conftest.c <<EOF +int _start (void) { return 42; } +EOF + if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp + -Wl,-z,start-stop-gc -nostdlib -nostartfiles + -fPIC -shared -o conftest.so conftest.c + 1>&5' + { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5 + (eval $ac_try) 2>&5 + ac_status=$? + $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5 + test $ac_status = 0; }; } + then + libc_linker_feature=yes + fi + rm -f conftest* + fi +fi +if test $libc_linker_feature = yes; then + libc_cv_z_start_stop_gc=yes +else + libc_cv_z_start_stop_gc=no +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_linker_feature" >&5 +$as_echo "$libc_linker_feature" >&6; } +config_vars="$config_vars +have-z-start-stop-gc = $libc_cv_z_start_stop_gc" + { $as_echo "$as_me:${as_lineno-$LINENO}: checking for linker that supports --no-dynamic-linker" >&5 $as_echo_n "checking for linker that supports --no-dynamic-linker... " >&6; } libc_linker_feature=no diff --git a/configure.ac b/configure.ac index fce967f2c2..4e2907da92 100644 --- a/configure.ac +++ b/configure.ac @@ -707,6 +707,22 @@ fi rm -f conftest*]) AC_SUBST(libc_cv_textrel_ifunc) +# Check if gcc supports attribute retain as it is used in attribute_used_retain macro. +AC_CACHE_CHECK([for gcc attribute retain support], + libc_cv_gcc_retain, [dnl +cat > conftest.c <<EOF +static int var __attribute__ ((used, retain, section ("__libc_atexit"))); +EOF +libc_cv_gcc_retain=no +if ${CC-cc} -Werror -c conftest.c -o /dev/null 1>&AS_MESSAGE_LOG_FD \ + 2>&AS_MESSAGE_LOG_FD ; then + libc_cv_gcc_retain=yes +fi +rm -f conftest*]) +if test $libc_cv_gcc_retain = yes; then + AC_DEFINE(HAVE_GCC_RETAIN) +fi + # Check if gcc warns about alias for function with incompatible types. AC_CACHE_CHECK([if compiler warns about alias for function with incompatible types], libc_cv_gcc_incompatible_alias, [dnl @@ -1317,6 +1333,10 @@ LIBC_LINKER_FEATURE([-z execstack], [-Wl,-z,execstack], [libc_cv_z_execstack=yes], [libc_cv_z_execstack=no]) AC_SUBST(libc_cv_z_execstack) +LIBC_LINKER_FEATURE([-z start-stop-gc], [-Wl,-z,start-stop-gc], + [libc_cv_z_start_stop_gc=yes], [libc_cv_z_start_stop_gc=no]) +LIBC_CONFIG_VAR([have-z-start-stop-gc], [$libc_cv_z_start_stop_gc]) + LIBC_LINKER_FEATURE([--no-dynamic-linker], [-Wl,--no-dynamic-linker], [libc_cv_no_dynamic_linker=yes], diff --git a/include/libc-symbols.h b/include/libc-symbols.h index 546fc26a7b..b311c90f0c 100644 --- a/include/libc-symbols.h +++ b/include/libc-symbols.h @@ -352,6 +352,12 @@ for linking") */ +#ifdef HAVE_GCC_RETAIN +# define attribute_used_retain __attribute__ ((__used__, __retain__)) +#else +# define attribute_used_retain __attribute__ ((__used__)) +#endif + /* Symbol set support macros. */ /* Make SYMBOL, which is in the text segment, an element of SET. */ @@ -367,12 +373,12 @@ for linking") /* When building a shared library, make the set section writable, because it will need to be relocated at run time anyway. */ # define _elf_set_element(set, symbol) \ - static const void *__elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *__elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #else # define _elf_set_element(set, symbol) \ - static const void *const __elf_set_##set##_element_##symbol##__ \ - __attribute__ ((used, section (#set))) = &(symbol) + static const void *const __elf_set_##set##_element_##symbol##__ \ + attribute_used_retain __attribute__ ((section (#set))) = &(symbol) #endif /* Define SET as a symbol set. This may be required (it is in a.out) to diff --git a/libio/Makefile b/libio/Makefile index 12ce41038f..439d22e057 100644 --- a/libio/Makefile +++ b/libio/Makefile @@ -195,6 +195,20 @@ ifeq (yes,$(build-shared)) tests-special += $(objpfx)tst-fopenloc-cmp.out $(objpfx)tst-fopenloc-mem.out \ $(objpfx)tst-bz24228-mem.out endif + +tests += tst-cleanup-default +tests-static += tst-cleanup-default +tests-special += $(objpfx)tst-cleanup-default-cmp.out +LDFLAGS-tst-cleanup-default = -Wl,--gc-sections + +ifeq ($(have-z-start-stop-gc),yes) +tests += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-static += tst-cleanup-start-stop-gc tst-cleanup-nostart-stop-gc +tests-special += $(objpfx)tst-cleanup-start-stop-gc-cmp.out \ + $(objpfx)tst-cleanup-nostart-stop-gc-cmp.out +LDFLAGS-tst-cleanup-start-stop-gc = -Wl,--gc-sections,-z,start-stop-gc +LDFLAGS-tst-cleanup-nostart-stop-gc = -Wl,--gc-sections,-z,nostart-stop-gc +endif endif include ../Rules @@ -224,6 +238,24 @@ $(objpfx)tst_wprintf2.out: $(gen-locales) $(objpfx)tst-wfile-sync.out: $(gen-locales) endif +$(objpfx)tst-cleanup-default-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-default.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-default.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-start-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-start-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-start-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + +$(objpfx)tst-cleanup-nostart-stop-gc-cmp.out: tst-cleanup.exp $(objpfx)tst-cleanup-nostart-stop-gc.out + cmp $^ > $@; \ + $(evaluate-test) +$(objpfx)tst-cleanup-nostart-stop-gc.o: tst-cleanup.c + $(compile.c) -o $@ + $(objpfx)test-freopen.out: test-freopen.sh $(objpfx)test-freopen $(SHELL) $< $(common-objpfx) '$(test-program-prefix)' \ $(common-objpfx)libio/; \ diff --git a/libio/tst-cleanup.c b/libio/tst-cleanup.c new file mode 100644 index 0000000000..7f0a34a91e --- /dev/null +++ b/libio/tst-cleanup.c @@ -0,0 +1,33 @@ +/* Copyright (C) 2021 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + <https://www.gnu.org/licenses/>. */ + +/* Test that stdout is flushed after atexit callbacks were run. */ + +#include <stdio.h> +#include <stdlib.h> + +void +hook (void) +{ + puts ("hello"); +} + +int +main (void) +{ + atexit (hook); +} diff --git a/libio/tst-cleanup.exp b/libio/tst-cleanup.exp new file mode 100644 index 0000000000..ce01362503 --- /dev/null +++ b/libio/tst-cleanup.exp @@ -0,0 +1 @@ +hello