Beginning with the upcoming 4.1 release, Linux on a subset of 32-bit
ARM hardware will provide fast user-space implementations of the
following system calls:
- gettimeofday
- clock_gettime
The kernel implementation depends on the ARMv7 Generic Timers
Extension to accelerate these system calls. So CPUs such as
Cortex-A15 and -A7 benefit, while Cortex-A9, -A8, and pre-v7 CPUs do
not. On systems where the VDSO does not provide any speedup, the
kernel prevents the relevant symbol lookups from succeeding.
On OMAP5 (Cortex-A15) gettimeofday latency decreases from ~350ns to
~120ns. On BeagleBone Black (Cortex-A8) it goes from ~650ns to
~660ns, which to my mind is an acceptable cost.
Verified that no new test failures are introduced on kernels with and
without the VDSO.
* sysdeps/unix/sysv/linux/arm/Makefile: (sysdep_routines):
Include dl-vdso.
* sysdeps/unix/sysv/linux/arm/init-first.c: New file:
Use VDSO routines for gettimeofday, clock_gettime if
available.
* sysdeps/unix/sysv/linux/arm/libc-vdso.h: New file:
Declare VDSO symbols.
* sysdeps/unix/sysv/linux/arm/sysdep.h:
[HAVE_GETTIMEOFDAY_VSYSCALL]: Define.
[HAVE_CLOCK_GETTIME_VSYSCALL]: Define.
* sysdeps/unix/sysv/linux/arm/Versions: Add
__vdso_clock_gettime.
This patch uses inline calls (through INLINE_SYSCALL macro) to define
the non-cancellable functions macros to avoid use of the
syscall_nocancel entrypoint.
This adds wake-ups that would be missing if assuming that for a
non-writer-preferring rwlock, if one thread has acquired a rdlock and
does not release it, another thread will eventually acquire a rdlock too
despite concurrent write lock acquisition attempts. BZ 14958 is about
supporting this assumption. Strictly speaking, this isn't a valid
test case, but nonetheless worth supporting (see comment 7 of BZ 14958).
If we set up a rwlock to prefer writers (and disallow recursive rdlock
acquisitions), then readers will block for writers that are blocked to
acquire the lock (otherwise, readers could constantly enter and exit,
and the writer would never get the lock). However, the existing
implementation did not wake such readers when the writer timed out.
This patch adds the missing wake-up.
There's no similar case for writers being blocked on readers.
fnmatch brings in references to strnlen, which isn't in all the
standards that contain fnmatch (not added until the 2008 edition of
POSIX), resulting in linknamespace test failures. (This is contrary
to glibc conventions, rather than a standards conformance issue,
because of the str* reservation.) This patch fixes this in the usual
way, using __strnlen instead of strnlen.
Tested for x86_64 and x86 (testsuite, and that installed stripped
shared libraries are unchanged by the patch).
[BZ #18470]
* posix/fnmatch.c (fnmatch) [_LIBC]: Call __strnlen instead of
strnlen.
* conform/Makefile (test-xfail-XPG3/fnmatch.h/linknamespace):
Remove variable.
(test-xfail-XPG4/fnmatch.h/linknamespace): Likewise.
(test-xfail-POSIX/fnmatch.h/linknamespace): Likewise.
(test-xfail-POSIX/glob.h/linknamespace): Likewise.
(test-xfail-POSIX/wordexp.h/linknamespace): Likewise.
(test-xfail-UNIX98/fnmatch.h/linknamespace): Likewise.
(test-xfail-UNIX98/glob.h/linknamespace): Likewise.
(test-xfail-UNIX98/wordexp.h/linknamespace): Likewise.
(test-xfail-XOPEN2K/fnmatch.h/linknamespace): Likewise.
(test-xfail-XOPEN2K/glob.h/linknamespace): Likewise.
(test-xfail-XOPEN2K/wordexp.h/linknamespace): Likewise.
fnmatch brings in references to wmemchr, which isn't in all the
standards that contain fnmatch, resulting in linknamespace test
failures. This patch fixes this in the usual way, making wmemchr into
a weak alias for __wmemchr.
Tested for x86_64 and x86 (testsuite, and that disassembly of
installed shared libraries is unchanged by the patch).
[BZ #18468]
* wcsmbs/wmemchr.c (wmemchr): Rename to __wmemchr and define as
weak alias of __wmemchr. Use libc_hidden_weak.
* include/wchar.h (__wmemchr): Declare. Use libc_hidden_proto.
* posix/fnmatch.c [HANDLE_MULTIBYTE] (MEMCHR): Use __wmemchr
instead of wmemchr.
Carlos noted in
<https://sourceware.org/ml/libc-alpha/2015-05/msg00680.html> that
various ports use potentially problematic short variables names in
their syscall macros, which could shadow variables with the same name
from containing scopes.
This patch fixes variables called err and ret in MIPS macros. (I left
result_var and _sys_result - separate variables in different macros,
which need separate names - alone.)
Tested for mips64 (all three ABIs) that installed stripped shared
libraries are unchanged by this patch.
* sysdeps/unix/sysv/linux/mips/mips32/sysdep.h (INLINE_SYSCALL):
Use variable name _sc_err instead of err.
[__mips16] (INTERNAL_SYSCALL_NCS): Use variable name _sc_ret
instead of ret.
* sysdeps/unix/sysv/linux/mips/mips64/n32/sysdep.h
(INLINE_SYSCALL): Use variable name _sc_err instead of err.
* sysdeps/unix/sysv/linux/mips/mips64/n64/sysdep.h
(INLINE_SYSCALL): Likewise.
Various code in glibc uses __strnlen instead of strnlen for namespace
reasons. However, __strnlen does not use libc_hidden_proto /
libc_hidden_def (as is normally done for any function defined and
called within the same library, whether or not exported from the
library and whatever namespace it is in), so the compiler does not
know that those calls are to a function within libc.
This patch uses libc_hidden_proto / libc_hidden_def with __strnlen.
On x86_64, it makes no difference to the installed stripped shared
libraries. On 32-bit x86, it causes __strnlen calls to go to the same
place as strnlen calls (the fallback strnlen implementation), rather
than through a PLT entry for the strnlen IFUNC; I'm not sure of the
logic behind when calls from within libc should use IFUNCs versus when
they should go direct to a particular function implementation, but
clearly it doesn't make sense for strnlen and __strnlen to be handled
differently in this regard.
Tested for x86_64 and x86 (testsuite, and comparison of installed
shared libraries as described above).
* string/strnlen.c [!STRNLEN] (__strnlen): Use libc_hidden_def.
* include/string.h (__strnlen): Use libc_hidden_proto.
* sysdeps/aarch64/strnlen.S (__strnlen): Use libc_hidden_def.
* sysdeps/i386/i686/multiarch/strnlen-c.c [SHARED]
(libc_hidden_def): Define __GI___strnlen as well as __GI_strnlen.
* sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-power7.S
(libc_hidden_def): Undefine and redefine.
* sysdeps/powerpc/powerpc32/power4/multiarch/strnlen-ppc32.c
[SHARED] (libc_hidden_def): Define __GI___strnlen as well as
__GI_strnlen.
* sysdeps/powerpc/powerpc32/power7/strnlen.S (__strnlen): Use
libc_hidden_def.
* sysdeps/tile/tilegx/strnlen.c (__strnlen): Likewise.
fnmatch brings in references to towlower (and thereby towupper), which
isn't in all the standards that contain fnmatch, resulting in
linknamespace test failures. (This is contrary to glibc conventions,
rather than a standards conformance issue, because of the to*
reservation.) This patch fixes this in the usual way, making those
functions into weak aliases.
Tested for x86_64 and x86 (testsuite, and that disassembly of
installed shared libraries is unchanged by the patch). This is on top
of <https://sourceware.org/ml/libc-alpha/2015-06/msg00019.html>, but
the two patches should be independent.
(The __attribute_pure__ on the declarations in include/wctype.h comes
from GCC's built-in attributes for towlower and towupper, and is
needed to get the same code generation for fnmatch before and after
the patch. It seems likely there are cases where the declaration of
__foo in the internal headers is missing attributes from foo in the
public headers, built-in to GCC or both, but I don't know a good way
to detect such missing attributes.)
[BZ #18469]
* wctype/wcfuncs.c (towlower): Rename to __towlower and define as
weak alias of __towlower. Use libc_hidden_weak.
(towupper): Rename to __towupper and define as weak alias of
__towupper. Use libc_hidden_weak.
* include/wctype.h (__towlower): Declare. Use libc_hidden_proto.
(__towupper): Likewise.
* posix/fnmatch.c [HANDLE_MULTIBYTE && _LIBC] (FOLD): Use
__towlower instead of towlower.
The attached patch fixes a glibc build failure with gcc 5 on powerpc64le
caused by a recent change in gcc where the compiler defines the
_ARCH_PWR6 macro when processing assembly files but doesn't invoke the
assembler in the corresponding machine mode (unless it has been
explicitly configured to target POWER 6 or later). A bug had been filed
with gcc for this (65341) but was closed as won't fix. Glibc relies on
the _ARCH_PWR6 macro in a few .S files to make use of Power ISA 2.5
instructions (specifically, the four-argument form of the mtfsf insn).
A similar problem had occurred in the past (bug 10118) but the fix that
was committed for it didn't anticipate this new problem.
This script is a sample implementation that uses import_bench to
construct two benchmark objects and compare them. If detailed timing
information is available (when one does `make DETAILED=1 bench`), it
writes out graphs for all functions it benchmarks and prints
significant differences in timings of the two benchmark runs. If
detailed timing information is not available, it points out
significant differences in aggregate times.
Call this script as follows:
compare_bench.py schema_file.json bench1.out bench2.out
Alternatively, if one wants to set a different threshold for warnings
(default is a 10% difference):
compare_bench.py schema_file.json bench1.out bench2.out 25
The threshold in the example above is 25%. schema_file.json is the
JSON schema (which is $srcdir/benchtests/scripts/benchout.schema.json
for the benchmark output file) and bench1.out and bench2.out are the
two benchmark output files to compare.
The key functionality here is the compress_timings function which
groups together points that are close together into a single point
that is the mean of all its representative points. Any point in such
a group is at most 1.5x the smallest point in that group. The
detailed derivation is a comment in the function.
* benchtests/scripts/compare_bench.py: New file.
* benchtests/scripts/import_bench.py (mean): New function.
(split_list): Likewise.
(do_for_all_timings): Likewise.
(compress_timings): Likewise.
This is the beginning of a module to import and process benchmark
outputs. The module currently supports importing of a bench.out and
validating it against a schema file. In future this could grow a set
of routines that benchmark consumers may find useful to build their
own analysis tools. I have altered validate_bench to use this module
too.
* benchtests/scripts/import_bench.py: New file.
* benchtests/scripts/validate_benchout.py: Import import_bench
instead of jsonschema.
(validate_bench): Remove function.
(main): Use import_bench.
PLT relocations aren't required when -z now used. Linker on master with:
commit 25070364b0ce33eed46aa5d78ebebbec6accec7e
Author: H.J. Lu <hjl.tools@gmail.com>
Date: Sat May 16 07:00:21 2015 -0700
Don't generate PLT relocations for now binding
There is no need for PLT relocations with -z now. We can use GOT
relocations, which take less space, instead and replace 16-byte .plt
entres with 8-byte .plt.got entries.
bfd/
* elf32-i386.c (elf_i386_check_relocs): Create .plt.got section
for now binding.
(elf_i386_allocate_dynrelocs): Use .plt.got section for now
binding.
* elf64-x86-64.c (elf_x86_64_check_relocs): Create .plt.got
section for now binding.
(elf_x86_64_allocate_dynrelocs): Use .plt.got section for now
binding.
won't generate PLT relocations with -z now. elf/tst-audit2.c expect
certain order of execution in ld.so. With PLT relocations, the GOTPLT
entry of calloc is update to calloc defined in tst-audit2:
(gdb) bt
skip_ifunc=<optimized out>, reloc_addr_arg=<optimized out>,
version=<optimized out>, sym=<optimized out>, map=<optimized out>)
at ../sysdeps/i386/dl-machine.h:329
out>,
nrelative=<optimized out>, relsize=<optimized out>,
reladdr=<optimized out>, map=<optimized out>) at do-rel.h:137
reloc_mode=reloc_mode@entry=0,
consider_profiling=1, consider_profiling@entry=0) at dl-reloc.c:258
user_entry=0xffffcf1c, auxv=0xffffd0a8) at rtld.c:2133
start_argptr=start_argptr@entry=0xffffcfb0,
dl_main=dl_main@entry=0xf7fda6f0 <dl_main>) at
../elf/dl-sysdep.c:249
from /export/build/gnu/glibc-32bit/build-i686-linux/elf/ld.so
(gdb)
and then calloc is called:
(gdb) c
Continuing.
Breakpoint 4, calloc (n=n@entry=20, m=4) at tst-audit2.c:18
18 {
(gdb) bt
reloc_mode=reloc_mode@entry=0, consider_profiling=1,
consider_profiling@entry=0) at dl-reloc.c:272
user_entry=0xffffcf1c, auxv=0xffffd0a8) at rtld.c:2133
start_argptr=start_argptr@entry=0xffffcfb0,
dl_main=dl_main@entry=0xf7fda6f0 <dl_main>) at
../elf/dl-sysdep.c:249
from /export/build/gnu/glibc-32bit/build-i686-linux/elf/ld.so
(gdb)
With GOT relocation, calloc in ld.so is called first:
(gdb) bt
consider_profiling=1) at dl-reloc.c:272
user_entry=0xffffcf0c, auxv=0xffffd098) at rtld.c:2074
start_argptr=start_argptr@entry=0xffffcfa0,
dl_main=dl_main@entry=0xf7fda6c0 <dl_main>) at
../elf/dl-sysdep.c:249
from /export/build/gnu/glibc-32bit-test/build-i686-linux/elf/ld.so
(gdb)
and then the GOT entry of calloc is updated:
(gdb) bt
skip_ifunc=<optimized out>, reloc_addr_arg=<optimized out>,
version=<optimized out>, sym=<optimized out>, map=<optimized out>)
at ../sysdeps/i386/dl-machine.h:329
out>,
nrelative=<optimized out>, relsize=<optimized out>,
reladdr=<optimized out>, map=<optimized out>) at do-rel.h:137
reloc_mode=reloc_mode@entry=0,
consider_profiling=1, consider_profiling@entry=0) at dl-reloc.c:258
user_entry=0xffffcf0c, auxv=0xffffd098) at rtld.c:2133
start_argptr=start_argptr@entry=0xffffcfa0,
dl_main=dl_main@entry=0xf7fda6c0 <dl_main>) at
../elf/dl-sysdep.c:249
from /export/build/gnu/glibc-32bit-test/build-i686-linux/elf/ld.so
(gdb)
After that, since calloc isn't called from ld.so nor any other modules,
magic in tst-audit2 isn't updated. Both orders are correct. This patch
makes sure that calloc in tst-audit2.c is called at least once from ld.so.
[BZ #18422]
* Makefile ($(objpfx)tst-audit2): Depend on $(libdl).
($(objpfx)tst-audit2.out): Also depend on
$(objpfx)tst-auditmod9b.so.
* elf/tst-audit2.c: Include <dlfcn.h>.
(calloc_called): New.
(calloc): Allow to be called more than once.
(do_test): dllopen/dlclose $ORIGIN/tst-auditmod9b.so.
On 2015-05-26 21:24, Siddhesh Poyarekar wrote:
> On Tue, May 26, 2015 at 05:13:07PM +0300, Marko Myllynen wrote:
>> this should be obvious, please commit if looks to be ok.
>>
>> 2015-05-26 Marko Myllynen <myllynen@redhat.com>
>>
>> * stdlib/monetary.h: Fix comment.
>
> Patch didn't apply to master, but I've fixed it up and pushed it.
sorry about that (a whitespace hickup) - but your patch changed the
wrong comment, so here's a new patch to fix the fix.
At issue for INLINE_SYSCALL was that it used "err" and "val"
as variable names in a #define, so that if it was used in a context
where the "caller" was also using "err" or "val", and those
variables were passed in to INLINE_SYSCALL, we would end up
referencing the internal shadowed variables instead.
For example, "char val" in check_may_shrink_heap() in
sysdeps/unix/sysv/linux/malloc-sysdep.h was being shadowed by
the syscall return "val" in INLINE_SYSCALL, causing the "char val"
not to get updated at all, and may_shrink_heap ended up always false.
A similar fix was made to INTERNAL_VSYSCALL_CALL.
This patch removes the architecture specific gettimeofday implementation
to use the vDSO symbol and consolidate it on a common Linux one.
Similar to clock_gettime and clock_getres vDSO implementation, each port
that supports gettimeofday through vDSO should just implement INLINE_VSYSCALL
to access the symbol and define HAVE_{GETTIME,GETRES}_VSYSCAL as 1.
In the introduction for the official orthography rules for Ukrainian
language (http://spelling.ulif.org.ua/peredmova.htm) there's a note
that only apostrophe does not affect order of the words when sorting.
As could be seen from the official alphabet the soft sign
(U+044C/U+042C) has its hard position and thus affects the order and
also letters "е" and "є" (CYR-IE: U+0435/U+0415 and UKR-IE:
U+0454/U+0404) have their own positions and should have separate place
when sorting.
This also corresponds to official Unicode collation chart for these
letters: http://unicode.org/charts/collation/chart_Cyrillic.html
On 21/05/15 05:29, Siddhesh Poyarekar wrote:
> On Wed, May 20, 2015 at 06:55:02PM +0100, Szabolcs Nagy wrote:
>> i guess it's ok for consistency if i fix struct stat64
>> too to use __USE_XOPEN2K8.
>>
>> i will run some tests and come back with a patch
>
> I also think it would be appropriate to change this code in other
> architectures (microblaze and nacl IIRC) to make all of them
> consistent. It is a mechanical enough change IMO that all arch
> maintainer acks is not necessary.
>
here is the patch with consistent __USE_XOPEN2K8
ok to commit?
2015-05-21 Szabolcs Nagy <szabolcs.nagy@arm.com>
[BZ #18234]
* conform/data/sys/stat.h-data (struct stat): Add tests for st_atim,
st_mtim and st_ctim members.
* sysdeps/nacl/bits/stat.h (struct stat, struct stat64): Make
st_atim, st_ctim, st_mtim visible under __USE_XOPEN2K8 only.
* sysdeps/unix/sysv/linux/generic/bits/stat.h (struct stat,):
(struct stat64): Likewise.
* sysdeps/unix/sysv/linux/ia64/bits/stat.h (struct stat,):
(struct stat64): Likewise.
* sysdeps/unix/sysv/linux/microblaze/bits/stat.h (struct stat,):
(struct stat64): Likewise.
This patch consolidate the Linux vDSO define and usage across all ports
that uses it. The common vDSO definitions and calling through
{INLINE/INTERNAL}_VSYSCALL macros are moved to a common header
sysdep-vdso.h and vDSO name declaration and prototype is defined
using a common macro.
Also PTR_{MANGLE,DEMANGLE} is added to ports that does not use them
for vDSO calls (aarch64, powerpc, s390, and tile) and thus it will
reflect in code changes. For ports that already implement pointer
mangling/demangling in vDSO system (i386, x32, x86_64) this patch
is mainly a code refactor.
Checked on x32, x86_64, x32, ppc64le, and aarch64.
A shared object doesn't need PLT if there are no PLT relocations. It
shouldn't be an error if DT_PLTRELSZ is missing.
[BZ #18410]
* elf/dl-reloc.c (_dl_relocate_object): Don't issue an error
for missing DT_PLTRELSZ.
[BZ #18412]
* intl/locale.alias: Remove obsolete aliases "bokmål" and "français"
which caused 'locale -a' to output Latin-1 data in UTF-8 locales,
breaking some applications that use 'locale -a' output.
Change the encoding of this file from Latin-1 to ASCII to avoid
other potential problems with people grepping this file.
This patch removes the socket.S implementation for all ports and replace
it by a C implementation using socketcall. For ports that implement
the syscall directly, there is no change.
The patch idea is to simplify the socket function implementation that
uses the socketcall to be based on C implemetation instead of a pseudo
assembly implementation with arch specific parts. The patch then remove
the assembly implementatation for the ports which uses socketcall
(i386, microblaze, mips, powerpc, sparc, m68k, s390 and sh).
I have cross-build GLIBC for afore-mentioned ports and tested on both
i386 and ppc32 without regressions.
The soft-fp implementations of fma produce -Wuninitialized warnings
because, in the cases where the result is not a nonzero finite value,
the soft-fp does not set the exponent of the result since the (cooked)
packing will do so, but the compiler does not then see that the
exponent is always set in packing before it's used if it wasn't set
earlier. This patch uses DIAG_* macros to suppress those warnings.
Tested for mips64. (In fact this allows the mips64 build to complete
with the -Wno-uninitialized removed from math/Makefile, but more
cleanups are still needed in the ldbl-128ibm code for uninitialized
warnings there.)
* soft-fp/fmadf4.c: Include <libc-internal.h>.
(__fma): Ignore uninitialized warnings around packing.
* soft-fp/fmasf4.c: Include <libc-internal.h>.
(__fmaf): Ignore uninitialized warnings around packing.
* soft-fp/fmatf4.c: Include <libc-internal.h>.
(__fmal): Ignore uninitialized warnings around packing.
The ldbl-128 and ldbl-128ibm implementations of tanl produce
uninitialized variable warnings with -Wuninitialized because of a
variable that is initialized only conditionally, then used under the
same conditions under which it is set. This patch uses DIAG_* macros
to suppress those warnings.
Tested for powerpc and mips64.
* sysdeps/ieee754/ldbl-128/k_tanl.c: Include <libc-internal.h>.
(__kernel_tanl): Ignore uninitialized warnings around use of SIGN.
* sysdeps/ieee754/ldbl-128ibm/k_tanl.c: Include <libc-internal.h>.
(__kernel_tanl): Ignore uninitialized warnings around use of SIGN.
The ldbl-128 and ldbl-128ibm implementations of erfcl produce
uninitialized variable warnings with -Wuninitialized because of switch
statements where in fact one of the cases will always be executed, but
the compiler does not see that these cases cover all possibilities
(and because the reasoning that it does involves inequalities on the
representation of a floating point value leading to a set of possible
values for 8.0 times that value, converted to int, it's highly
nontrivial for the compiler to see that). This patch fixes those
warnings by converting the last case in those switch statements to a
"default" case.
Tested for powerpc and mips64.
* sysdeps/ieee754/ldbl-128/s_erfl.c (__erfcl): Make case 9 in
switch statement into default case.
* sysdeps/ieee754/ldbl-128ibm/s_erfl.c (__erfcl): Likewise.
The ldbl-128 and ldbl-128ibm implementations of asinl produce
uninitialized variable warnings with -Wuninitialized because the code
for small arguments in fact always returns but the compiler cannot see
this and instead sees that a variable would be uninitialized if the
"if (huge + x > one)" conditional used to force the "inexact"
exception were false.
All the code in libm trying to force "inexact" for functions that are
not exactly defined is suspect and should be removed at some point
given that we now have a clear definition of the accuracy goals for
libm functions which, following C99/C11, does not require anything
about "inexact" for most functions (likewise, the multi-precision code
that tries to give correctly-rounded results, very slowly, for
functions for which the goals clearly do not include correct rounding,
if the faster paths are accurate enough). However, for now this patch
simply changes the code to use math_force_eval, rather than "if", to
ensure the evaluation of the inexact computation.
Tested for powerpc and mips64.
* sysdeps/ieee754/ldbl-128/e_asinl.c (__ieee754_asinl): Don't use
a conditional in forcing "inexact".
* sysdeps/ieee754/ldbl-128ibm/e_asinl.c (__ieee754_asinl):
Likewise.
My review of conformtest expectations for POSIX showed up that the
_POSIX2_C_VERSION macro, required by POSIX and XPG standards before
2001, was missing in unistd.h, having been removed on 2003-04-03
despite those standards still being supported. This patch adds it
back. As it's in the implementation namespace, there's no need for it
to be conditional, and other such macros aren't conditional in this
header either.
Tested for x86_64 and x86 (testsuite). Note that this *does* change
the installed libraries, because it affects the sysconf support
(present all along) for _SC_2_C_VERSION.
[BZ #438]
* posix/unistd.h (_POSIX2_C_VERSION): New macro.
* conform/Makefile (test-xfail-POSIX/unistd.h/conform): Remove
variable.
pathconf (sysdeps/unix/sysv/linux/pathconf.c) uses basename. But
pathconf is in POSIX back to 1990 while basename is only reserved with
external linkage in those standards including XPG functions. This
patch fixes this namespace issue in the usual way, renaming basename
to __basename and making it into a weak alias.
Tested for x86_64 and x86 (testsuite, and that disassembly of
installed shared libraries is unchanged by the patch).
[BZ #18444]
* string/basename.c (basename): Rename to __basename and define as
weak alias of __basename. Use libc_hidden_weak.
* include/string.h (__basename): Declare. Use libc_hidden_proto.
* sysdeps/unix/sysv/linux/pathconf.c (distinguish_extX): Call
__basename instead of basename.
* conform/Makefile (test-xfail-POSIX2008/unistd.h/linknamespace):
Remove variable.
(test-xfail-XOPEN2K8/unistd.h/linknamespace): Likewise.
