Remove support for NO_CTORS_DTORS_SECTIONS
Commit Message
As far as I can tell, no architecture currently needs this. The
build-many-glibcs.py logs I have show that the configure check for
.ctors/.dtors sections always fails.
This is part of my efforts to rework the early initialization code in
preparation for rseq support.
Tested on x86_64-linux-gnu, i686-linux-gnu, s390x-linux-gnu,
powerpc64le-linux-gnu, aarch64-linux-gnu. Built with
build-many-glibcs.py (compilers followed by glibcs).
2019-10-08 Florian Weimer <fweimer@redhat.com>
Remove support for NO_CTORS_DTORS_SECTIONS.
* Makerules (libc.so): Do not link with soinit.os.
(linkobj/libc.so): Likewise.
* config.h.in (NO_CTORS_DTORS_SECTIONS): Remove definition.
* configure.ac: Remove check for NO_CTORS_DTORS_SECTIONS.
* configure: Regenerate.
* csu/init-first.c (_init): Remove call to __libc_global_ctors.
* elf/Makefile (extra-objs): Remove soinit.os.
* elf/sofini.c (__CTOR_END__, __DTOR_END__): Remove definitions.
* elf/sonit.c: Remove file.
* include/libc-internal.h (__libc_global_ctors): Remove
declaration.
* sysdeps/mach/hurd/i386/init-first.c (__libc_global_ctors):
Remove declaration.
(posixland_init): Remove call to __libc_global_ctors.
Comments
On Tue, 8 Oct 2019, Florian Weimer wrote:
> As far as I can tell, no architecture currently needs this. The
> build-many-glibcs.py logs I have show that the configure check for
> .ctors/.dtors sections always fails.
I don't think this was meant to be architecture-specific. It was added in
<https://sourceware.org/ml/libc-alpha/2010-12/msg00051.html>; the relevant
linker feature appears to have been added in binutils 2.22 (which is older
than the oldest supported binutils version for building glibc).
* Joseph Myers:
> On Tue, 8 Oct 2019, Florian Weimer wrote:
>
>> As far as I can tell, no architecture currently needs this. The
>> build-many-glibcs.py logs I have show that the configure check for
>> .ctors/.dtors sections always fails.
>
> I don't think this was meant to be architecture-specific. It was added in
> <https://sourceware.org/ml/libc-alpha/2010-12/msg00051.html>; the relevant
> linker feature appears to have been added in binutils 2.22 (which is older
> than the oldest supported binutils version for building glibc).
Thanks. I have changed the commit message to this:
Remove support for NO_CTORS_DTORS_SECTIONS
This was originally added to support binutils older than version
2.22:
<https://sourceware.org/ml/libc-alpha/2010-12/msg00051.html>
Since 2.22 is older than the minimum required binutils version
for building glibc, we no longer need this. (The changes do
not impact the statically linked startup code.)
Tested on x86_64-linux-gnu, i686-linux-gnu, s390x-linux-gnu,
powerpc64le-linux-gnu, aarch64-linux-gnu. Built with
build-many-glibcs.py (compilers followed by glibcs).
Okay for master?
Florian
@@ -690,8 +690,7 @@ $(common-objpfx)linkobj/libc.so: link-libc-deps = # empty
# Use our own special initializer and finalizer files for the libc.so
# libraries.
-$(common-objpfx)libc.so: $(elf-objpfx)soinit.os \
- $(common-objpfx)libc_pic.os$(libc_pic_clean) \
+$(common-objpfx)libc.so: $(common-objpfx)libc_pic.os$(libc_pic_clean) \
$(elf-objpfx)sofini.os \
$(elf-objpfx)interp.os \
$(elf-objpfx)ld.so \
@@ -699,8 +698,7 @@ $(common-objpfx)libc.so: $(elf-objpfx)soinit.os \
$(build-shlib)
$(call after-link,$@)
-$(common-objpfx)linkobj/libc.so: $(elf-objpfx)soinit.os \
- $(common-objpfx)linkobj/libc_pic.a \
+$(common-objpfx)linkobj/libc.so: $(common-objpfx)linkobj/libc_pic.a \
$(elf-objpfx)sofini.os \
$(elf-objpfx)interp.os \
$(elf-objpfx)ld.so \
@@ -160,9 +160,6 @@
/* Define if multi-arch DSOs should be generated. */
#undef USE_MULTIARCH
-/* Define if `.ctors' and `.dtors' sections shouldn't be used. */
-#undef NO_CTORS_DTORS_SECTIONS
-
/* Define if obsolete RPC code should be made available for user-level code
to link against. */
#undef LINK_OBSOLETE_RPC
@@ -5731,59 +5731,6 @@ if test $libc_cv_have_sdata_section = yes; then
fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to use .ctors/.dtors header and trailer" >&5
-$as_echo_n "checking whether to use .ctors/.dtors header and trailer... " >&6; }
-if ${libc_cv_ctors_header+:} false; then :
- $as_echo_n "(cached) " >&6
-else
- libc_cv_ctors_header=yes
- cat > conftest.c <<EOF
-int _start (void) { return 0; }
-int __start (void) { return 0; }
-
-__attribute__ ((constructor)) void ctor (void) { asm (""); }
-__attribute__ ((destructor)) void dtor (void) { asm (""); }
-
-EOF
-if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS $no_ssp -o conftest
- conftest.c -static -nostartfiles -nostdlib
- 1>&5'
- { { eval echo "\"\$as_me\":${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 :
- if $READELF -WS conftest$ac_exeext | $AWK '
- { gsub(/\[ */, "[") }
- $2 == ".ctors" || $2 == ".dtors" {
- size = strtonum("0x" $6)
- align = strtonum("0x" $NF)
- seen[$2] = 1
- stub[$2] = size == align * 2
- }
- END {
- ctors_ok = !seen[".ctors"] || stub[".ctors"]
- dtors_ok = !seen[".dtors"] || stub[".dtors"]
- exit ((ctors_ok && dtors_ok) ? 0 : 1)
- }
- '; then :
- libc_cv_ctors_header=no
-fi
-
-else
- as_fn_error $? "missing __attribute__ ((constructor)) support??" "$LINENO" 5
-
-fi
-rm -f conftest*
-
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_ctors_header" >&5
-$as_echo "$libc_cv_ctors_header" >&6; }
-if test $libc_cv_ctors_header = no; then
- $as_echo "#define NO_CTORS_DTORS_SECTIONS 1" >>confdefs.h
-
-fi
-
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for libunwind-support in compiler" >&5
$as_echo_n "checking for libunwind-support in compiler... " >&6; }
if ${libc_cv_cc_with_libunwind+:} false; then :
@@ -1243,36 +1243,6 @@ if test $libc_cv_have_sdata_section = yes; then
AC_DEFINE(HAVE_SDATA_SECTION)
fi
-AC_CACHE_CHECK(whether to use .ctors/.dtors header and trailer,
- libc_cv_ctors_header, [dnl
- libc_cv_ctors_header=yes
- LIBC_TRY_LINK_STATIC([
-__attribute__ ((constructor)) void ctor (void) { asm (""); }
-__attribute__ ((destructor)) void dtor (void) { asm (""); }
-],
- [dnl
- AS_IF([$READELF -WS conftest$ac_exeext | $AWK '
- { gsub(/\@<:@ */, "@<:@") }
- $2 == ".ctors" || $2 == ".dtors" {
- size = strtonum("0x" $6)
- align = strtonum("0x" $NF)
- seen@<:@$2@:>@ = 1
- stub@<:@$2@:>@ = size == align * 2
- }
- END {
- ctors_ok = !seen@<:@".ctors"@:>@ || stub@<:@".ctors"@:>@
- dtors_ok = !seen@<:@".dtors"@:>@ || stub@<:@".dtors"@:>@
- exit ((ctors_ok && dtors_ok) ? 0 : 1)
- }
- '], [libc_cv_ctors_header=no])
- ], [dnl
- AC_MSG_ERROR([missing __attribute__ ((constructor)) support??])
- ])
-])
-if test $libc_cv_ctors_header = no; then
- AC_DEFINE(NO_CTORS_DTORS_SECTIONS)
-fi
-
AC_CACHE_CHECK(for libunwind-support in compiler,
libc_cv_cc_with_libunwind, [
cat > conftest.c <<EOF
@@ -82,10 +82,6 @@ _init (int argc, char **argv, char **envp)
/* Initialize ctype data. */
__ctype_init ();
-
-#if defined SHARED && !defined NO_CTORS_DTORS_SECTIONS
- __libc_global_ctors ();
-#endif
}
/* This function is defined here so that if this file ever gets into
@@ -91,7 +91,7 @@ ld-map = $(common-objpfx)ld.map
endif
ifeq (yes,$(build-shared))
-extra-objs = $(all-rtld-routines:%=%.os) soinit.os sofini.os interp.os
+extra-objs = $(all-rtld-routines:%=%.os) sofini.os interp.os
generated += librtld.os dl-allobjs.os ld.so ldd
install-others = $(inst_rtlddir)/$(rtld-installed-name)
install-bin-script = ldd
@@ -1,15 +1,3 @@
-/* Finalizer module for ELF shared C library. This provides terminating
- null pointer words in the `.ctors' and `.dtors' sections. */
-
-#ifndef NO_CTORS_DTORS_SECTIONS
-static void (*const __CTOR_END__[1]) (void)
- __attribute__ ((used, section (".ctors")))
- = { 0 };
-static void (*const __DTOR_END__[1]) (void)
- __attribute__ ((used, section (".dtors")))
- = { 0 };
-#endif
-
/* Terminate the frame unwind info section with a 4byte 0 as a sentinel;
this would be the 'length' field in a real FDE. */
deleted file mode 100644
@@ -1,43 +0,0 @@
-/* Initializer module for building the ELF shared C library. This file and
- sofini.c do the work normally done by crtbeginS.o and crtendS.o, to wrap
- the `.ctors' and `.dtors' sections so the lists are terminated, and
- calling those lists of functions. */
-
-#ifndef NO_CTORS_DTORS_SECTIONS
-# include <stdlib.h>
-
-static void (*const __CTOR_LIST__[1]) (void)
- __attribute__ ((used, section (".ctors")))
- = { (void (*) (void)) -1 };
-static void (*const __DTOR_LIST__[1]) (void)
- __attribute__ ((used, section (".dtors")))
- = { (void (*) (void)) -1 };
-
-static inline void
-run_hooks (void (*const list[]) (void))
-{
- while (*++list)
- (**list) ();
-}
-
-/* This function will be called from _init in init-first.c. */
-void
-__libc_global_ctors (void)
-{
- /* Call constructor functions. */
- run_hooks (__CTOR_LIST__);
-}
-
-
-/* This function becomes the DT_FINI termination function
- for the C library. */
-void
-__libc_fini (void)
-{
- /* Call destructor functions. */
- run_hooks (__DTOR_LIST__);
-}
-
-void (*_fini_ptr) (void) __attribute__ ((section (".fini_array")))
- = &__libc_fini;
-#endif
@@ -24,9 +24,6 @@
/* Initialize the `__libc_enable_secure' flag. */
extern void __libc_init_secure (void);
-/* This function will be called from _init in init-first.c. */
-extern void __libc_global_ctors (void);
-
/* Discover the tick frequency of the machine if something goes wrong,
we return 0, an impossible hertz. */
extern int __profile_frequency (void);
@@ -33,7 +33,6 @@
extern void __mach_init (void);
extern void __init_misc (int, char **, char **);
-extern void __libc_global_ctors (void);
unsigned long int __hurd_threadvar_stack_offset;
unsigned long int __hurd_threadvar_stack_mask;
@@ -86,10 +85,6 @@ posixland_init (int argc, char **argv, char **envp)
/* Initialize ctype data. */
__ctype_init ();
-
-#if defined SHARED && !defined NO_CTORS_DTORS_SECTIONS
- __libc_global_ctors ();
-#endif
}