On i386, when multi-arch is enabled, all external functions must be
called via PIC PLT in PIE, which requires setting up EBX register,
since they may be IFUNC functions.
* config.h.in (NO_HIDDEN_EXTERN_FUNC_IN_PIE): New.
* include/libc-symbols.h (__hidden_proto_hiddenattr): Add check
for PIC and NO_HIDDEN_EXTERN_FUNC_IN_PIE.
* sysdeps/i386/configure.ac (NO_HIDDEN_EXTERN_FUNC_IN_PIE): New
AC_DEFINE if multi-arch is enabled.
* sysdeps/i386/configure: Regenerated.
On the Hurd, the rtld needs to see its own dumb versions of a few functions
(defined in sysdeps/mach/hurd/dl-sysdep.c) overridden by libc's versions once
loaded. rtld should thus not have hidden attribute for these. To achieve this,
the Hurd port used to just define NO_HIDDEN, which disables it completely. For
now, this changes that to disabling it for all rtld functions, for simplicity.
See Roland's comment on https://sourceware.org/bugzilla/show_bug.cgi?id=15605#c5
The ld.so numbers remain at
8 .rel.plt 000000c8 00000c24 00000c24 00000c24 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .plt 000001a0 00000cf0 00000cf0 00000cf0 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
10 .plt.got 00000010 00000e90 00000e90 00000e90 2**3
CONTENTS, ALLOC, LOAD, READONLY, CODE
18 .got.plt 00000070 0002d000 0002d000 0002c000 2**2
CONTENTS, ALLOC, LOAD, DATA
which is about 3 times as much as on Linux.
The libc.so numbers get divided by 3 (the remainings are mostly RPC stub calls)
* include/libc-symbols.h [NO_RTLD_HIDDEN] (rtld_hidden_proto,
rtld_hidden_tls_proto, rtld_hidden_def, rtld_hidden_weak,
rtld_hidden_rtld_hidden_ver, data_def, rtld_hidden_data_weak,
rtld_hidden_data_ver): Define to empty.
* include/assert.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__assert_fail,
__assert_perror_fail): Likewise.
* include/dirent.h [IS_IN(rtld) && NO_RTLD_HIDDEN]
(__rewinddir): Likewise.
* include/libc-internal.h [IS_IN(rtld) && NO_RTLD_HIDDEN]
(__profile_frequency): Likewise.
* include/setjmp.h (__sigsetjmp): Likewise.
* include/signal.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__sigaction,
__libc_sigaction): Likewise.
* include/stdlib.h [NO_RTLD_HIDDEN] (unsetenv, __strtoul_internal): Do
not set hidden attribute.
* include/string.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__stpcpy, __strdup,
__strerror_t, __strsep_g, memchr, memcmp, memcpy, memmove, memset,
rawmemchr, stpcpy, strchr, strcmp, strlen, strnlen, strsep): Likewise.
* include/sys/stat.h [IS_IN(rtld) && NO_RTLD_HIDDEN] (__fxstat,
__fxstat64, __lxstat, __lxstat64, __xstat, __xstat64,
__fxstatat64): Likewise.
* include/sys/utsname.h [IS_IN(rtld) && NO_RTLD_HIDDEN]
(__uname): Likewise.
* include/sysdeps/generic/_itoa.h [IS_IN(rtld) && NO_RTLD_HIDDEN]
(_itoa_upper_digits, _itoa_lower_digits): Likewise.
* sysdeps/mach/hurd/configure.ac (NO_HIDDEN): Do not set.
(NO_RTLD_HIDDEN): Set.
* sysdeps/mach/hurd/configure: Refresh.
* config.h.in: Refresh.
Since Martin Sebor's commit
commit ee4e992ebe
Author: Martin Sebor <msebor@redhat.com>
Date: Tue Aug 22 09:35:23 2017 -0600
Declare ifunc resolver to return a pointer to the same type as the target
function to help GCC detect incompatibilities between the two when it's
enhanced to do so.
builds for powerpc64le fail in the declaration of some ifunc resolvers,
because the ifunc is declared with unmatching return types. One of the
declarations comes from the __ifunc_resolver macro, which was patched by
the aforementioned commit:
/* Helper / base macros for indirect function symbols. */
#define __ifunc_resolver(type_name, name, expr, arg, init, classifier) \
classifier inhibit_stack_protector \
__typeof (type_name) *name##_ifunc (arg) \
whereas the other comes from the unpatched __ifunc macro when
HAVE_GCC_IFUNC is not defined:
# define __ifunc(type_name, name, expr, arg, init) \
extern __typeof (type_name) name; \
void *name##_ifunc (arg) __asm__ (#name); \
This patch changes the return type of the ifunc resolver in the __ifunc
macro, so that it matches the return type of the target function,
similarly to what the aforementioned commit does.
Tested for powerpc64le and s390x with unpatched GCC.
* include/libc-symbols.h: [!defined HAVE_GCC_IFUNC] (__ifunc):
Change the return type of the ifunc resolver to match the return
type of the target function.
Add hidden visibility to internal function prototypes to allow direct
access to internal functions within libc.a without using GOT when the
compiler defaults to -fPIE.
Size comparison of elf/ldconfig when the compiler defaults to -fPIE:
On x86-64:
text data bss dec hex
Before: 619646 20132 5488 645266 9d892
After : 619502 20132 5488 645122 9d802
On i686:
text data bss dec hex
Before: 550333 10748 3060 564141 89bad
After : 546453 10732 3060 560245 88c75
* include/libc-symbols.h (__hidden_proto_hiddenattr): New for
building libc.a.
(hidden_proto): Likewise.
(hidden_tls_proto): Likewise.
(__hidden_proto): Likewise.
(Reapplied after the revert in df1deda60050cc8a68156cf6c81ad42363647a29.)
The commit
commit 568ff4296c
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Mon Aug 21 05:50:38 2017 -0700
Add hidden visibility to internal function prototypes
breaks the build of the testsuite for many platforms:
https://sourceware.org/ml/libc-testresults/2017-q3/msg00300.html
The errors are of the following form, building math/atest-exp:
[...]
/scratch/jmyers/glibc-bot/build/glibcs/aarch64-linux-gnu/glibc/stdlib/rshift.o: In function `__mpn_rshift':
/scratch/jmyers/glibc-bot/build/glibcs/aarch64-linux-gnu/glibc-src/stdlib/rshift.c:45: undefined reference to `__assert_fail'
/scratch/jmyers/glibc-bot/install/compilers/aarch64-linux-gnu/lib/gcc/aarch64-glibc-linux-gnu/7.2.1/../../../../aarch64-glibc-linux-gnu/bin/ld: /scratch/jmyers/glibc-bot/build/glibcs/aarch64-linux-gnu/glibc/math/atest-exp: hidden symbol `__assert_fail' isn't defined
/scratch/jmyers/glibc-bot/install/compilers/aarch64-linux-gnu/lib/gcc/aarch64-glibc-linux-gnu/7.2.1/../../../../aarch64-glibc-linux-gnu/bin/ld: final link failed: Bad value
This test is using various objects from the build of libc. Some of
those objects contain references to __assert_fail. Because those
references are hidden, they cannot refer to __assert_fail from
libc.so. Given the tests using internal objects those symbols in
libc.a can't safely be made hidden, so this patch reverts the problem
commit until any alternative approach that doesn't break the build can
be found.
Add hidden visibility to internal function prototypes to allow direct
access to internal functions within libc.a without using GOT when the
compiler defaults to -fPIE.
Size comparison of elf/ldconfig when the compiler defaults to -fPIE:
On x86-64:
text data bss dec hex
Before: 619646 20132 5488 645266 9d892
After : 619502 20132 5488 645122 9d802
On i686:
text data bss dec hex
Before: 550333 10748 3060 564141 89bad
After : 546453 10732 3060 560245 88c75
* include/libc-symbols.h (__hidden_proto_hiddenattr): New for
building libc.a.
(hidden_proto): Likewise.
(hidden_tls_proto): Likewise.
(__hidden_proto): Likewise.
When building libc.a with PIE, enable hidden visibility to allow direct
access to definitions within libc.a without using GOT.
Size comparison of elf/ldconfig when the compiler defaults to -fPIE:
On x86-64:
text data bss dec hex
Before: 619206 20132 5488 644826 9d6da
After : 619062 20132 5488 644682 9d64a
On i686:
text data bss dec hex
Before: 556305 10816 3056 570177 8b341
After : 553688 10756 3056 567500 8a8cc
* include/libc-symbols.h (attribute_hidden): Enable hidden
visibility in libc.a compiled with PIE.
On Linux/i386, there are 3 ways to make a system call:
1. call *%gs:SYSINFO_OFFSET. This requires TLS initialization.
2. call *_dl_sysinfo. This requires relocation of _dl_sysinfo.
3. int $0x80. This is slower than #2 and #3, but works everywhere.
When an object file is compiled with PIC, #1 is prefered since it is
faster than #3 and doesn't require relocation of _dl_sysinfo. For
dynamic executables, ld.so initializes TLS. However, for static
executables, before TLS is initialized by __libc_setup_tls, #3 should
be used for system calls.
This patch adds <startup.h> which defines _startup_fatal and defaults
it to __libc_fatal. It replaces __libc_fatal with _startup_fatal in
static executables where it is called before __libc_setup_tls is called.
This header file is included in all files containing functions which are
called before __libc_setup_tls is called. On Linux/i386, when PIE is
enabled by default, _startup_fatal is turned into ABORT_INSTRUCTION and
I386_USE_SYSENTER is defined to 0 so that "int $0x80" is used for system
calls before __libc_setup_tls is called.
Tested on i686 and x86-64. Without this patch, all statically-linked
tests will fail on i686 when the compiler defaults to -fPIE.
[BZ #21913]
* csu/libc-tls.c: Include <startup.h> first.
(__libc_setup_tls): Call _startup_fatal instead of __libc_fatal.
* elf/dl-tunables.c: Include <startup.h> first.
* include/libc-symbols.h (BUILD_PIE_DEFAULT): New.
* sysdeps/generic/startup.h: New file.
* sysdeps/unix/sysv/linux/i386/startup.h: Likewise.
* sysdeps/unix/sysv/linux/i386/brk.c [BUILD_PIE_DEFAULT != 0]
(I386_USE_SYSENTER): New. Defined to 0.
This patch adds a new build module called 'testsuite'.
IS_IN (testsuite) implies _ISOMAC, as do IS_IN_build and __cplusplus
(which means several ad-hoc tests for __cplusplus can go away).
libc-symbols.h now suppresses almost all of *itself* when _ISOMAC is
defined; in particular, _ISOMAC mode does not get config.h
automatically anymore.
There are still quite a few tests that need to see internal gunk of
one variety or another. For them, we now have 'tests-internal' and
'test-internal-extras'; files in this category will still be compiled
with MODULE_NAME=nonlib, and everything proceeds as it always has.
The bulk of this patch is moving tests from 'tests' to
'tests-internal'. There is also 'tests-static-internal', which has
the same effect on files in 'tests-static', and 'modules-names-tests',
which has the *inverse* effect on files in 'modules-names' (it's
inverted because most of the things in modules-names are *not* tests).
For both of these, the file must appear in *both* the new variable and
the old one.
There is also now a special case for when libc-symbols.h is included
without MODULE_NAME being defined at all. (This happens during the
creation of libc-modules.h, and also when preprocessing Versions
files.) When this happens, IS_IN is set to be always false and
_ISOMAC is *not* defined, which was the status quo, but now it's
explicit.
The remaining changes to C source files in this patch seemed likely to
cause problems in the absence of the main change. They should be
relatively self-explanatory. In a few cases I duplicated a definition
from an internal header rather than move the test to tests-internal;
this was a judgement call each time and I'm happy to change those
however reviewers feel is more appropriate.
* Makerules: New subdir configuration variables 'tests-internal'
and 'test-internal-extras'. Test files in these categories will
still be compiled with MODULE_NAME=nonlib. Test files in the
existing categories (tests, xtests, test-srcs, test-extras) are
now compiled with MODULE_NAME=testsuite.
New subdir configuration variable 'modules-names-tests'. Files
which are in both 'modules-names' and 'modules-names-tests' will
be compiled with MODULE_NAME=testsuite instead of
MODULE_NAME=extramodules.
(gen-as-const-headers): Move to tests-internal.
(do-tests-clean, common-mostlyclean): Support tests-internal.
* Makeconfig (built-modules): Add testsuite.
* Makefile: Change libof-check-installed-headers-c and
libof-check-installed-headers-cxx to 'testsuite'.
* Rules: Likewise. Support tests-internal.
* benchtests/strcoll-inputs/filelist#en_US.UTF-8:
Remove extra-modules.mk.
* config.h.in: Don't check for __OPTIMIZE__ or __FAST_MATH__ here.
* include/libc-symbols.h: Move definitions of _GNU_SOURCE,
PASTE_NAME, PASTE_NAME1, IN_MODULE, IS_IN, and IS_IN_LIB to the
very top of the file and rationalize their order.
If MODULE_NAME is not defined at all, define IS_IN to always be
false, and don't define _ISOMAC.
If any of IS_IN (testsuite), IS_IN_build, or __cplusplus are
true, define _ISOMAC and suppress everything else in this file,
starting with the inclusion of config.h.
Do check for inappropriate definitions of __OPTIMIZE__ and
__FAST_MATH__ here, but only if _ISOMAC is not defined.
Correct some out-of-date commentary.
* include/math.h: If _ISOMAC is defined, undefine NO_LONG_DOUBLE
and _Mlong_double_ before including math.h.
* include/string.h: If _ISOMAC is defined, don't expose
_STRING_ARCH_unaligned. Move a comment to a more appropriate
location.
* include/errno.h, include/stdio.h, include/stdlib.h, include/string.h
* include/time.h, include/unistd.h, include/wchar.h: No need to
check __cplusplus nor use __BEGIN_DECLS/__END_DECLS.
* misc/sys/cdefs.h (__NTHNL): New macro.
* sysdeps/m68k/m680x0/fpu/bits/mathinline.h
(__m81_defun): Use __NTHNL to avoid errors with GCC 6.
* elf/tst-env-setuid-tunables.c: Include config.h with _LIBC
defined, for HAVE_TUNABLES.
* inet/tst-checks-posix.c: No need to define _ISOMAC.
* intl/tst-gettext2.c: Provide own definition of N_.
* math/test-signgam-finite-c99.c: No need to define _ISOMAC.
* math/test-signgam-main.c: No need to define _ISOMAC.
* stdlib/tst-strtod.c: Convert to test-driver. Split locale_test to...
* stdlib/tst-strtod1i.c: ...this new file.
* stdlib/tst-strtod5.c: Convert to test-driver and add copyright notice.
Split tests of __strtod_internal to...
* stdlib/tst-strtod5i.c: ...this new file.
* string/test-string.h: Include stdint.h. Duplicate definition of
inhibit_loop_to_libcall here (from libc-symbols.h).
* string/test-strstr.c: Provide dummy definition of
libc_hidden_builtin_def when including strstr.c.
* sysdeps/ia64/fpu/libm-symbols.h: Suppress entire file in _ISOMAC
mode; no need to test __STRICT_ANSI__ nor __cplusplus as well.
* sysdeps/x86_64/fpu/math-tests-arch.h: Include cpu-features.h.
Don't include init-arch.h.
* sysdeps/x86_64/multiarch/test-multiarch.h: Include cpu-features.h.
Don't include init-arch.h.
* elf/Makefile: Move tst-ptrguard1-static, tst-stackguard1-static,
tst-tls1-static, tst-tls2-static, tst-tls3-static, loadtest,
unload, unload2, circleload1, neededtest, neededtest2,
neededtest3, neededtest4, tst-tls1, tst-tls2, tst-tls3,
tst-tls6, tst-tls7, tst-tls8, tst-dlmopen2, tst-ptrguard1,
tst-stackguard1, tst-_dl_addr_inside_object, and all of the
ifunc tests to tests-internal.
Don't add $(modules-names) to test-extras.
* inet/Makefile: Move tst-inet6_scopeid_pton to tests-internal.
Add tst-deadline to tests-static-internal.
* malloc/Makefile: Move tst-mallocstate and tst-scratch_buffer to
tests-internal.
* misc/Makefile: Move tst-atomic and tst-atomic-long to tests-internal.
* nptl/Makefile: Move tst-typesizes, tst-rwlock19, tst-sem11,
tst-sem12, tst-sem13, tst-barrier5, tst-signal7, tst-tls3,
tst-tls3-malloc, tst-tls5, tst-stackguard1, tst-sem11-static,
tst-sem12-static, and tst-stackguard1-static to tests-internal.
Link tests-internal with libpthread also.
Don't add $(modules-names) to test-extras.
* nss/Makefile: Move tst-field to tests-internal.
* posix/Makefile: Move bug-regex5, bug-regex20, bug-regex33,
tst-rfc3484, tst-rfc3484-2, and tst-rfc3484-3 to tests-internal.
* stdlib/Makefile: Move tst-strtod1i, tst-strtod3, tst-strtod4,
tst-strtod5i, tst-tls-atexit, and tst-tls-atexit-nodelete to
tests-internal.
* sunrpc/Makefile: Move tst-svc_register to tests-internal.
* sysdeps/powerpc/Makefile: Move test-get_hwcap and
test-get_hwcap-static to tests-internal.
* sysdeps/unix/sysv/linux/Makefile: Move tst-setgetname to
tests-internal.
* sysdeps/x86_64/fpu/Makefile: Add all libmvec test modules to
modules-names-tests.
gnulib now has annotations on at least some functions to cater to
compilation with -Wunused-parameter. In order to follow suit cleanly,
I've added to libc-symbols.h some of the _GL_* macros that
gnulib-common.m4 puts into config.h. (I don't think they belong in
sys/cdefs.h, at least not without further thought.)
At this point all gnulib-side changes to getopt.c have been merged.
* include/libc-symbols.h: For gnulib compatibility, define
_GL_UNUSED, _GL_UNUSED_LABEL, _GL_ATTRIBUTE_PURE, and
_GL_ATTRIBUTE_CONST.
* posix/getopt.c (_getopt_initialize): Mark argc and argv
parameters with _GL_UNUSED.
When dynamically linking, ifunc resolvers are called before TLS is
initialized, so they cannot be safely stack-protected.
We avoid disabling stack-protection on large numbers of files by
using __attribute__ ((__optimize__ ("-fno-stack-protector")))
to turn it off just for the resolvers themselves. (We provide
the attribute even when statically linking, because we will later
use it elsewhere too.)
For many years, the only effect of these macros has been to make
unistd.h declare getlogin_r. _POSIX_C_SOURCE >= 199506L also causes
this function to be declared. However, people who don't carefully
read all the headers might be confused into thinking they need to
define _REENTRANT for any threaded code (as was indeed the case a long
time ago).
Therefore, remove __USE_REENTRANT, and make _REENTRANT and _THREAD_SAFE
into synonyms for _POSIX_C_SOURCE=199506L. This will only affect
programs that don't select a higher conformance level some other way.
For instance, -std=c89 -D_REENTRANT will see a change in visible
declarations, but -std=c99 -D_POSIX_C_SOURCE=200809L -D_REENTRANT won't,
and -D_REENTRANT all by itself also won't, because _DEFAULT_SOURCE
implies _POSIX_C_SOURCE > 199506.
* include/features.h: Remove __USE_REENTRANT. Treat _REENTRANT
and _THREAD_SAFE the same as _POSIX_C_SOURCE=199506L, if a higher
POSIX conformance level has not been selected by other macros.
* NEWS, manual/creature.texi: Document this change.
* posix/unistd.h, posix/bits/unistd.h: Don't check __USE_REENTRANT.
* include/libc-symbols.h: Don't define _REENTRANT.
* scripts/check-installed-headers.sh: Don't undefine _REENTRANT.
This patch uses the libc_ifunc_hidden macro to create already existing ifunc functions
time and gettimeofday on intel. This way, the libc_hidden_def macro can be used
instead of the libc_ifunc_hidden_def one which was only used here. Thus the
macro is removed from libc-symbols.h.
On i386, the __GI_* symbols do not target the ifunc symbol and thus the
redirection construct has to be applied here.
ChangeLog:
* sysdeps/unix/sysv/linux/x86/gettimeofday.c (__gettimeofday):
Use libc_ifunc_hidden macro. Use libc_hidden_def instead of
libc_ifunc_hidden_def.
* sysdeps/unix/sysv/linux/x86/time.c (time): Likewise.
* sysdeps/unix/sysv/linux/i386/gettimeofday.c (__gettimeofday):
Redirect ifunced function in header for using it as type of ifunc'ed
function. Redefine libc_hidden_def to use fallback non ifunc'ed
function for __GI_* symbol.
* sysdeps/unix/sysv/linux/i386/time.c (time): Likewise.
* include/libc-symbols.h
(libc_ifunc_hidden_def, libc_ifunc_hidden_def1): Delete macro.
The current s390 ifunc resolver for vector optimized functions and the common
libc_ifunc macro in include/libc-symbols.h uses something like that to generate ifunc'ed functions:
extern void *__resolve___strlen(unsigned long int dl_hwcap) asm (strlen);
asm (".type strlen, %gnu_indirect_function");
This leads to false debug information:
objdump --dwarf=info libc.so:
...
<1><1e6424>: Abbrev Number: 43 (DW_TAG_subprogram)
<1e6425> DW_AT_external : 1
<1e6425> DW_AT_name : (indirect string, offset: 0x1146e): __resolve___strlen
<1e6429> DW_AT_decl_file : 1
<1e642a> DW_AT_decl_line : 23
<1e642b> DW_AT_linkage_name: (indirect string, offset: 0x1147a): strlen
<1e642f> DW_AT_prototyped : 1
<1e642f> DW_AT_type : <0x1e4ccd>
<1e6433> DW_AT_low_pc : 0x998e0
<1e643b> DW_AT_high_pc : 0x16
<1e6443> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa)
<1e6445> DW_AT_GNU_all_call_sites: 1
<1e6445> DW_AT_sibling : <0x1e6459>
<2><1e6449>: Abbrev Number: 44 (DW_TAG_formal_parameter)
<1e644a> DW_AT_name : (indirect string, offset: 0x1845): dl_hwcap
<1e644e> DW_AT_decl_file : 1
<1e644f> DW_AT_decl_line : 23
<1e6450> DW_AT_type : <0x1e4c8d>
<1e6454> DW_AT_location : 0x122115 (location list)
...
The debuginfo for the ifunc-resolver function contains the DW_AT_linkage_name
field, which names the real function name "strlen". If you perform an inferior
function call to strlen in lldb, then it fails due to something like that:
"error: no matching function for call to 'strlen'
candidate function not viable: no known conversion from 'const char [6]'
to 'unsigned long' for 1st argument"
The unsigned long is the dl_hwcap argument of the resolver function.
The strlen function itself has no debufinfo.
The s390 ifunc resolver for memset & co uses something like that:
asm (".globl FUNC"
".type FUNC, @gnu_indirect_function"
".set FUNC, __resolve_FUNC");
This way the debuginfo for the ifunc-resolver function does not conain the
DW_AT_linkage_name field and the real function has no debuginfo, too.
Using this strategy for the vector optimized functions leads to some troubles
for functions like strnlen. Here we have __strnlen and a weak alias strnlen.
The __strnlen function is the ifunc function, which is realized with the asm-
statement above. The weak_alias-macro can't be used here due to undefined symbol:
gcc ../sysdeps/s390/multiarch/strnlen.c -c ...
In file included from <command-line>:0:0:
../sysdeps/s390/multiarch/strnlen.c:28:24: error: ‘strnlen’ aliased to undefined symbol ‘__strnlen’
weak_alias (__strnlen, strnlen)
^
./../include/libc-symbols.h:111:26: note: in definition of macro ‘_weak_alias’
extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
^
../sysdeps/s390/multiarch/strnlen.c:28:1: note: in expansion of macro ‘weak_alias’
weak_alias (__strnlen, strnlen)
^
make[2]: *** [build/string/strnlen.o] Error 1
As the __strnlen function is defined with asm-statements the function name
__strnlen isn't known by gcc. But the weak alias can also be done with an
asm statement to resolve this issue:
__asm__ (".weak strnlen\n\t"
".set strnlen,__strnlen\n");
In order to use the weak_alias macro, gcc needs to know the ifunc function. The
minimum gcc to build glibc is currently 4.7, which supports attribute((ifunc)).
See https://gcc.gnu.org/onlinedocs/gcc-4.7.0/gcc/Function-Attributes.html.
It is only supported if gcc is configured with --enable-gnu-indirect-function
or gcc supports it by default for at least intel and s390x architecture.
This patch uses the old behaviour if gcc support is not available.
Usage of attribute ifunc is something like that:
__typeof (FUNC) FUNC __attribute__ ((ifunc ("__resolve_FUNC")));
Then gcc produces the same .globl, .type, .set assembler instructions like above.
And the debuginfo does not contain the DW_AT_linkage_name field and there is no
debuginfo for the real function, too.
But in order to get it work, there is also some extra work to do.
Currently, the glibc internal symbol on s390x e.g. __GI___strnlen is not the
ifunc symbol, but the fallback __strnlen_c symbol. Thus I have to omit the
libc_hidden_def macro in strnlen.c (here is the ifunc function __strnlen)
because it is already handled in strnlen-c.c (here is __strnlen_c).
Due to libc_hidden_proto (__strnlen) in string.h, compiling fails:
gcc ../sysdeps/s390/multiarch/strnlen.c -c ...
In file included from <command-line>:0:0:
../sysdeps/s390/multiarch/strnlen.c:53:24: error: ‘strnlen’ aliased to undefined symbol ‘__strnlen’
weak_alias (__strnlen, strnlen)
^
./../include/libc-symbols.h:111:26: note: in definition of macro ‘_weak_alias’
extern __typeof (name) aliasname __attribute__ ((weak, alias (#name)));
^
../sysdeps/s390/multiarch/strnlen.c:53:1: note: in expansion of macro ‘weak_alias’
weak_alias (__strnlen, strnlen)
^
make[2]: *** [build/string/strnlen.os] Error 1
I have to redirect the prototypes for __strnlen in string.h and create a copy
of the prototype for using as ifunc function:
__typeof (__redirect___strnlen) __strnlen __attribute__ ((ifunc ("__resolve_strnlen")));
weak_alias (__strnlen, strnlen)
This way there is no trouble with the internal __GI_* symbols.
Glibc builds fine with this construct and the debuginfo is "correct".
For functions without a __GI_* symbol like memccpy this redirection is not needed.
This patch adjusts the common libc_ifunc and libm_ifunc macro to use gcc
attribute ifunc. Due to this change, the macro users where the __GI_* symbol
does not target the ifunc symbol have to be prepared with the redirection
construct.
Furthermore a configure check to test gcc support is added. If it is not supported,
the old behaviour is used.
This patch also prepares the libc_ifunc macro to be useable in s390-ifunc-macro.
The s390 ifunc-resolver-functions do have an hwcaps parameter and not all
resolvers need the same initialization code. The next patch in this series
changes the s390 ifunc macros to use this common one.
ChangeLog:
* include/libc-symbols.h (__ifunc_resolver):
New macro is used by __ifunc* macros.
(__ifunc): New macro uses gcc attribute ifunc or inline assembly
depending on HAVE_GCC_IFUNC.
(libc_ifunc, libm_ifunc): Use __ifunc as base macro.
(libc_ifunc_redirected, libc_ifunc_hidden, libm_ifunc_init): New macro.
* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_finite.c:
Redirect ifunced function in header for using as type for ifunc function.
* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_finitef.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_isinf.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_isinff.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_isnan.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/memcmp.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/memcpy.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/memmove.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/mempcpy.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/memset.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/rawmemchr.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/strchr.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/strlen.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/strncmp.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/multiarch/strnlen.c: Likewise.
* sysdeps/powerpc/powerpc64/fpu/multiarch/s_finite.c: Likewise.
* sysdeps/powerpc/powerpc64/fpu/multiarch/s_finitef.c: Likewise.
* sysdeps/powerpc/powerpc64/fpu/multiarch/s_isinf.c: Likewise.
* sysdeps/powerpc/powerpc64/fpu/multiarch/s_isinff.c: Likewise.
* sysdeps/powerpc/powerpc64/fpu/multiarch/s_isnan.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/memcmp.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/mempcpy.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/rawmemchr.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/stpncpy.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/strcat.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/strchr.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/strcmp.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/strcpy.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/strncmp.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/strncpy.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/strnlen.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/strrchr.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/strstr.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/wcschr.c: Likewise.
* sysdeps/powerpc/powerpc32/power4/fpu/multiarch/s_isnanf.c:
Add libc_hidden_def() and use libc_ifunc_hidden() macro
instead of libc_ifunc() macro.
* sysdeps/powerpc/powerpc64/fpu/multiarch/s_isnanf.c: Likewise.
* sysdeps/powerpc/powerpc64/multiarch/stpcpy.c: Likewise.
Existing interposed mallocs do not define the glibc-internal
fork callbacks (and they should not), so statically interposed
mallocs lead to link failures because the strong reference from
fork pulls in glibc's malloc, resulting in multiple definitions
of malloc-related symbols.
There are configure tests for assembler .weak support, and, as a
fallback, for .weakext support.
.weakext appears to be an ECOFF thing (although a few ELF targets
support it as well). .weak has been supported by the GNU assembler
for ELF targets since version 2.2, so given the requirement for ELF
the configure tests are obsolete; this patch removes them.
Tested for x86_64 (testsuite, and that installed shared libraries are
unchanged by the patch).
* configure.ac (libc_cv_asm_weak_directive): Remove configure
test.
(libc_cv_asm_weakext_directive): Likewise.
* configure: Regenerated.
* config.h.in (HAVE_ASM_WEAK_DIRECTIVE): Remove #undef.
(HAVE_ASM_WEAKEXT_DIRECTIVE): Likewise.
* include/libc-symbols.h
[!HAVE_ASM_WEAK_DIRECTIVE && !HAVE_ASM_WEAKEXT_DIRECTIVE]: Remove
#error.
[HAVE_ASM_WEAKEXT_DIRECTIVE]: Remove conditional code.
[!HAVE_ASM_WEAKEXT_DIRECTIVE]: Make code unconditional.
There is a configure test for the assembler .previous directive, and,
as a fallback, for .popsection.
glibc now only supports ELF. For ELF, the GNU assembler has supported
.previous since version 2.2 (support added by
Mon Jul 19 15:21:20 1993 Ken Raeburn (raeburn@rtl.cygnus.com)
* config/obj-elf.c (obj_elf_previous): New function.
(previous_section, previous_subsection): New vars.
(obj_elf_section): Save current place in case DWARF code wants us
to pop back to it. Handle unquoted section name as well as quoted
section name. Don't crash on invalid strings.
(obj_pseudo_table): Handle new pseudos "previous", "2byte", and
"4byte".
). Thus this configure test is obsolete, and this patch removes it
(and with it the fallback .popsection test).
Tested for x86_64 and x86 (testsuite, and that installed shared
libraries are unchanged by the patch).
* configure.ac (libc_cv_asm_previous_directive): Remove configure
test.
(libc_cv_asm_popsection_directive): Likewise.
* configure: Regenerated.
* config.h.in (HAVE_ASM_PREVIOUS_DIRECTIVE): Remove #undef.
(HAVE_ASM_POPSECTION_DIRECTIVE): Likewise.
* include/libc-symbols.h [HAVE_ASM_PREVIOUS_DIRECTIVE]
(__make_section_unallocated): Make definition unconditional.
[HAVE_ASM_POPSECTION_DIRECTIVE] (__make_section_unallocated):
Remove conditional definition.
[!HAVE_ASM_PREVIOUS_DIRECTIVE && !HAVE_ASM_POPSECTION_DIRECTIVE]
(__make_section_unallocated): Likewise.
With AIX port deprecated there is no need to check/define
HAVE_ASM_GLOBAL_DOT_NAME anymore since the current minimum binutils
supported (2.22) does not emit global symbol with dot.
This patch removes all the HAVE_ASM_GLOBAL_DOT_NAME definition and
checks for powerpc64 port.
Replace with IS_IN and IS_IN_LIB macros instead. This change results
in a change in generated code, because it fixes a subtle bug. The bug
was introduced when systemtap probes were added to lowlevellock.h,
which resulted in stap-probe.h being included in a number of places.
stap-probe.h always defines IN_LIB, which breaks a check in errno.h
and netdb.h since they rely on that macro to decide whether to
implement an internal version of a declaration or an external one.
The components that see a code change due to this are:
iconv_prog
libmemusage.so
libpcprofile.so
libSegFault.so
libutil.so.1
locale
localedef
nscd
All other built components (i.e. libc, libpthread, etc.) remain
unchanged by this on x86_64.
* elf/Makefile (CPPFLAGS-.os): Remove IN_LIB.
* elf/rtld-Rules (rtld-CPPFLAGS): Likewise.
* extra-lib.mk (CPPFLAGS-$(lib)): Likewise.
* include/libc-symbols.h (IS_IN_LIB): New macro.
* include/errno.h: Use IS_IN_LIB instead of IN_LIB.
* include/netdb.h: Likewise.
* include/stap-probe.h: Remove all uses of IN_LIB.
Define MODULE_NAME in the build command and define IN_MODULE using
MODULE_NAME. Verified that the generated code is unchanged on x86_64.
* Makeconfig (module-cppflags-real): Define MODULE_NAME
instead of IN_MODULE.
* include/libc-symbols.h (IN_MODULE): Define using
MODULE_NAME.
(PASTE_NAME, PASTE_NAME1): New macros.
* include/stap-probe.h (LIBC_PROBE_1): Use MODULE_NAME instead
of IN_LIB.
(STAP_PROBE_ASM): Likewise.
Remove libc-modules.h from the tree and auto-generate it from
soversions.i and the list of modules in the built-modules variable
defined in Makeconfig. Macros generated have increasing numbered
values, with built-modules having lower values starting from 1,
following which a separator value LIBS_BEGIN is added and then finally
the library names from soversions.i are appended to the list. This
allows us to conveniently differentiate between the versioned
libraries and other built modules, which is needed in errno.h and
netdb.h to decide whether to use an internal symbol or an external
one.
Verified that generated code remains unchanged on x86_64.
* Makeconfig (built-modules): List non-library modules to be
built.
(module-cppflags): Include libc-modules.h for
everything except shlib-versions.v.i.
(CPPFLAGS): Use it.
(before-compile): Add libc-modules.h.
($(common-objpfx)libc-modules.h,
$(common-objpfx)libc-modules.stmp): New targets.
(common-generated): Add libc-modules.h and libc-modules.stmp.
($(common-objpfx)Versions.v.i): Depend on libc-modules.h.
* include/libc-symbols.h: Don't include libc-modules.h.
* include/libc-modules.h: Remove file.
* scripts/gen-libc-modules.awk: New script to generate
libc-modules.h.
* sysdeps/unix/Makefile ($(common-objpfx)sysd-syscalls):
Depend on libc-modules.stmp.
The current scheme to identify which module a translation unit is
built in depends on defining multiple macros IS_IN_* and also defining
NOT_IN_libc if we're building a non-libc module. In addition, there
is an IN_LIB macro that does effectively the same thing, but for
different modules (notably the systemtap probes). This macro scheme
unifies both ideas to use just one macro IN_MODULE and assign it a
value depending on the module it is being built into. If the module
is not defined, it defaults to MODULE_libc.
Patches that follow will replace uses of IS_IN_* variables with the
IS_IN() macro. libc-symbols.h has been converted already to give an
example of how such a transition will look.
Verified that there are no relevant binary changes. One source change
that will crop up repeatedly is that of nscd_stat, since it uses the
build timestamp as a constant in its logic.
* Makeconfig (in-module): Get value of libof set for the
translation unit.
(CPPFLAGS): Use $(in-module).
* Makerules: Don't suffix routine names for nonlib.
* include/libc-modules.h: New file.
* include/libc-symbols.h: Include libc-modules.h
(IS_IN): New macro to replace IS_IN_* macros.
* elf/Makefile: Set libof-* for each routine.
* elf/rtld-Rules: Likewise.
* extra-modules.mk: Likewise.
* iconv/Makefile: Likewise.
* iconvdata/Makefile: Likewise.
* locale/Makefile: Likewise.
* malloc/Makefile: Likewise.
* nss/Makefile: Likewise.
* sysdeps/gnu/Makefile: Likewise.
* sysdeps/ieee754/ldbl-opt/Makefile: Likewise.
* sysdeps/unix/sysv/linux/Makefile: Likewise.
* sysdeps/s390/s390-64/Makefile: Likewise.
* nscd/Makefile: Set libof-* for each routine. Set CFLAGS and
CPPFLAGS for nscd instead of nonlib.
Completing the removal of the obsolete INTDEF / INTUSE mechanism, this
patch removes the final use - that for _dl_starting_up - replacing it
by rtld_hidden_def / rtld_hidden_proto. Having removed the last use,
the mechanism itself is also removed.
Tested for x86_64 that installed stripped shared libraries are
unchanged by the patch. (This is not much of a test since this
variable is only defined and used in the !HAVE_INLINED_SYSCALLS case.)
[BZ #14132]
* include/libc-symbols.h (INTUSE): Remove macro.
(INTDEF): Likewise.
(INTVARDEF): Likewise.
(_INTVARDEF): Likewise.
(INTDEF2): Likewise.
(INTVARDEF2): Likewise.
* elf/rtld.c [!HAVE_INLINED_SYSCALLS] (_dl_starting_up): Use
rtld_hidden_def instead of INTVARDEF.
* sysdeps/generic/ldsodefs.h [IS_IN_rtld]
(_dl_starting_up_internal): Remove declaration.
(_dl_starting_up): Use rtld_hidden_proto.
* elf/dl-init.c [!HAVE_INLINED_SYSCALLS] (_dl_starting_up): Remove
declaration.
[!HAVE_INLINED_SYSCALLS] (_dl_starting_up_internal): Likewise.
(_dl_init) [!HAVE_INLINED_SYSCALLS]: Don't use INTUSE with
_dl_starting_up.
* elf/dl-writev.h (_dl_writev): Likewise.
* sysdeps/powerpc/powerpc64/dl-machine.h [!HAVE_INLINED_SYSCALLS]
(DL_STARTING_UP_DEF): Use __GI__dl_starting_up instead of
_dl_starting_up_internal.
Fixes -Wundef warnings for MBSTATE_T and HAVE_STRING_H. The
HAVE_STRING_H bit is a merge from the gnulib fnmatch.c and the
MBSTATE_T fix has been posted to gnulib for inclusion.
Check wheter the compiler has the option -fno-tree-loop-distribute-patterns
to inhibit loop transformation to library calls and uses it on memset
and memmove default implementation to avoid recursive calls.
New configure option --enable-obsolete-rpc makes the deprecated RPC
headers and functions available at compile time as they were before
version 2.14. This option will be removed at some time in the future
after the TI-RPC library becomes fully sufficient for the needs of
existing applications.
