The recently introduced TLS variables in the thread-local destructor
implementation (__cxa_thread_atexit_impl) used the default GD access
model, resulting in a call to __tls_get_addr. This causes a deadlock
with recent changes to the way TLS is initialized because DTV
allocations are delayed and hence despite knowing the offset to the
variable inside its TLS block, the thread has to take the global rtld
lock to safely update the TLS offset.
This causes deadlocks when a thread is instantiated and joined inside
a destructor of a dlopen'd DSO. The correct long term fix is to
somehow not take the lock, but that will need a lot deeper change set
to alter the way in which the big rtld lock is used.
Instead, this patch just eliminates the call to __tls_get_addr for the
thread-local variables inside libc.so, libpthread.so and rtld by
building all of their units with -mtls-model=initial-exec.
There were concerns that the static storage for TLS is limited and
hence we should not be using it. Additionally, dynamically loaded
modules may result in libc.so looking for this static storage pretty
late in static binaries. Both concerns are valid when using TLSDESC
since that is where one may attempt to allocate a TLS block from
static storage for even those variables that are not IE. They're not
very strong arguments for the traditional TLS model though, since it
assumes that the static storage would be used sparingly and definitely
not by default. Hence, for now this would only theoretically affect
ARM architectures.
The impact is hence limited to statically linked binaries that dlopen
modules that in turn load libc.so, all that on arm hardware. It seems
like a small enough impact to justify fixing the larger problem that
currently affects everything everywhere.
This still does not solve the original problem completely. That is,
it is still possible to deadlock on the big rtld lock with a small
tweak to the test case attached to this patch. That problem is
however not a regression in 2.22 and hence could be tackled as a
separate project. The test case is picked up as is from Alex's patch.
This change has been tested to verify that it does not cause any
issues on x86_64.
ChangeLog:
[BZ #18457]
* nptl/Makefile (tests): New test case tst-join7.
(modules-names): New test case module tst-join7mod.
* nptl/tst-join7.c: New file.
* nptl/tst-join7mod.c: New file.
* Makeconfig (tls-model): Pass -ftls-model=initial-exec for
all translation units in libc.so, libpthread.so and rtld.
glibc supports the deprecated matherr hook for math error reporting. The
conform tests take this into consideration and whitelist this symbol when
running linknamespace tests.
The ia64 libm code has long provided two additional hooks in this space:
matherrf (for floats)
matherrl (for long doubles)
Which causes the conform tests to fail with chains that all look like:
[initial] __atan2 ->
[libm.a(e_atan2.o)] __libm_error_support ->
[libm.a(libm_error.o)] matherrf
We can't (losslessly) redirect existing usage of these funcs to matherr
because the structure passed in is different -- matherr uses a struct with
doubles while matherrf/matherrl use floats and long doubles respectively.
Plus, this has been part of the exported ABI since glibc-2.2.3, so it
doesn't feel right to change it so late.
Until we get around to obsoleting matherr entirely, whitelist these two
additional ia64 symbols.
Since ia64 is little endian, sa_flags has to come before the padding
when splitting it from 64bits to 32bits.
Reported-by: Joseph Myers <joseph@codesourcery.com>
When an TLS destructor is registered, we set the DF_1_NODELETE flag to
signal that the object should not be destroyed. We then clear the
DF_1_NODELETE flag when all destructors are called, which is wrong -
the flag could have been set by other means too.
This patch replaces this use of the flag by using l_tls_dtor_count
directly to determine whether it is safe to unload the object. This
change has the added advantage of eliminating the lock taking when
calling the destructors, which could result in a deadlock. The patch
also fixes the test case tst-tls-atexit - it was making an invalid
dlclose call, which would just return an error silently.
I have also added a detailed note on concurrency which also aims to
justify why I chose the semantics I chose for accesses to
l_tls_dtor_count. Thanks to Torvald for his help in getting me
started on this and (literally) teaching my how to approach the
problem.
Change verified on x86_64; the test suite does not show any
regressions due to the patch.
ChangeLog:
[BZ #18657]
* elf/dl-close.c (_dl_close_worker): Don't unload DSO if there
are pending TLS destructor calls.
* include/link.h (struct link_map): Add concurrency note for
L_TLS_DTOR_COUNT.
* stdlib/cxa_thread_atexit_impl.c (__cxa_thread_atexit_impl):
Don't touch the link map flag. Atomically increment
l_tls_dtor_count.
(__call_tls_dtors): Atomically decrement l_tls_dtor_count.
Avoid taking the load lock and don't touch the link map flag.
* stdlib/tst-tls-atexit-nodelete.c: New test case.
* stdlib/Makefile (tests): Use it.
* stdlib/tst-tls-atexit.c (do_test): dlopen
tst-tls-atexit-lib.so again before dlclose. Add conditionals
to allow tst-tls-atexit-nodelete test case to use it.
It turns out tile suffered from the same problem as S390. However,
disabling CFI information for the __startcontext on tile was not
sufficient to fix the problem; I think the backtracer will just
blindly try to follow the link register (lr) in that case.
Instead, the change adds a cfi_undefined directive for "lr"
and then arranges to call __startcontext directly when the new
context starts, rather than just synthesizing a return to it.
In addition to being a bit easier now to understand the control
flow, this also allows the cfi_undefined directive to be placed in
a way that causes it to be in force at the address that the "lr"
from the called function points to.
repertoire maps and character mnemonics were used early in the glibc
i18n/l10n effort but were quickly deprecated in favor of Unicode code
points. According to ChangeLog, the in-tree repertoire maps were
removed 2000-07-07 but some stray references remain even today. The
patch below removes them.
After renaming localedef now complains and build fails
LC_ADDRESS: field `lang_ab' must not be defined
earlier the names were similar to lang_ab definitions 'tu' or 'bh'
but after rename they are not.
Commit a059d359d8 changed the sigaction
struct to pass conform tests, but it ended up also changing the ABI for
32 bit builds. For 64 bit builds, changing the long to two ints works,
but for 32 bit builds, it inserts 4 extra bytes. This leads to many
packages randomly failing like bash that spews things like:
configure: line 471: wait_for: No record of process 0
Bracket the new member by a wordsize check to fix the ABI for 32bit.
The tst-tls-atexit test case searches for its module in /proc/PID/maps
to verify that it is unloaded, which is a Linux-specific test. This
patch makes the test generic by looking for the library in the link
map list in the _r_debug structure.
Verified that the test continues to succeed on x86_64. There is a bug
in the test case where it calls dlclose once again, which is actually
incorrect but still manages to unload the DSO thanks to an existing
bug in __tls_call_dtors. This will be fixed in a later patch which
also fixes up the __cxa_thread_atexit_impl implementation. I have
added a FIXME comment to that call momentarily, which I will remove
when I fix the problem.
* stdlib/tst-tls-atexit-lib.c (do_foo): Rename to reg_dtor.
* stdlib/tst-tls-atexit.c: (is_loaded): New function.
(spawn_thread): New function.
(load): Rename to reg_dtor_and_close. Move dlopen to...
(do_test): ... here. Use IS_LOADED to test for its
availability.
X86 struct siginfo in kernel 3.19 has been changed by
commit ee1b58d36aa1b5a79eaba11f5c3633c88231da83
Author: Qiaowei Ren <qiaowei.ren@intel.com>
Date: Fri Nov 14 07:18:19 2014 -0800
mpx: Extend siginfo structure to include bound violation information
This patch adds new fields about bound violation into siginfo
structure. si_lower and si_upper are respectively lower bound
and upper bound when bound violation is caused.
This patch updates x86 struct siginfo to enable GDB with MPX support.
[BZ #18696]
* sysdeps/unix/sysv/linux/x86/bits/siginfo.h (_sigfault): Add
si_addr_bnd.
(si_lower): New.
(si_upper): Likewise.
If 'w' mode is used with a provided buffer the fmemopen will try to find
the first null byte to set as maximum internal stream size. It should be
done only for append mode ('a').
Kudos for Stefan Liebler for finding this error on s390-32.
* libio/fmemopen.c (__fmemopen): Fix 'w' openmode with provided
buffer.
* stdio-common/tst-fmemopen2.c (do_test_with_buffer): Fix typo and
fail output information.
This patch optimizes strstr function for power >= 7 systems. Performance
gain is obtained using aligned memory access and usage of cmpb
instruction for quicker comparison. The average improvement of this
optimization is ~40%. Tested on ppc64 and ppc64le.
2015-07-16 Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com>
* sysdeps/powerpc/powerpc64/multiarch/Makefile: Add strstr().
* sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c: Likewise.
* sysdeps/powerpc/powerpc64/power7/strstr.S: New File.
* sysdeps/powerpc/powerpc64/multiarch/strstr-power7.S: New File.
* sysdeps/powerpc/powerpc64/multiarch/strstr-ppc64.c: New File.
* sysdeps/powerpc/powerpc64/multiarch/strstr.c: New File.
This symbol is only used by DL_UNMAP which in turn is only used by
_dl_close_worker in dl-close.c, and _dl_close_worker itself is marked
hidden as it is only used by the ldso. That means _dl_unmap should
be marked hidden. Without this, the elf/check-localplt test fails.
This symbol is defined in the ldso, and is used both there and libc.so.
There is no hidden symbol for it though which leads to relocations in
the ldso and the elf/check-localplt test failing. Add a hidden def for
rtld to fix all of that.
This function/file is only used by hppa & ia64, so no testing is needed
for other arches.
The DF_1_NODELETE flag is set too late when opening a DSO, due to
which, if a DSO is already open, subsequently opening it with
RTLD_NODELETE fails to set the DF_1_NODELETE flag. This patch fixes
this by setting the flag immediately after bumping the opencount.
Verified on x86_64.
[BZ #18676]
* elf/tst-nodelete-opened.c: New test case.
* elf/tst-nodelete-opened-lib.c: New test case module.
* elf/Makefile (tests, modules-names): Use them.
* elf/dl-open.c (dl_open_worker): Set DF_1_NODELETE flag
early.
Bhili [1] and Tulu [2] language does not have iso-639-1 codes. Patch
moves locale file with correct code and also fix iso-639.def.
1. http://www-01.sil.org/iso639-3/documentation.asp?id=bhb
2. http://www-01.sil.org/iso639-3/documentation.asp?id=tcy
localedata/ChangeLog:
2015-07-02 Pravin Satpute <psatpute@redhat.com>
[BZ #17475]
* locales/tu_IN: renamed to tcy_IN
* locales/bh_IN: renamed to bhb_IN
Changelog:
2015-03-05 Pravin Satpute <psatpute@redhat.com>
[BZ #17475]
* locale/iso-639.def: Update Bhili and Tulu language codes as
per iso639-3.
These tests were skipped by the use-test-skeleton conversion done in
commit 29955b5d because they were reused in other tests via the #include
directive, and so deemed worth an inspection before they were modified.
This has now been done.
ChangeLog:
2015-07-09 Arjun Shankar <arjun.is@lostca.se>
* elf/tst-leaks1.c (main): Converted to ...
(do_test): ... this.
(TEST_FUNCTION): New macro.
Include test-skeleton.c.
* localedata/tst-langinfo.c (main): Converted to ...
(do_test): ... this.
(TEST_FUNCTION): New macro.
Include test-skeleton.c.
* math/test-fpucw.c (main): Converted to ...
(do_test): ... this.
(TEST_FUNCTION): New macro.
Include test-skeleton.c.
* math/test-tgmath.c (main): Converted to ...
(do_test): ... this.
(TEST_FUNCTION): New macro.
Include test-skeleton.c.
* math/test-tgmath2.c (main): Converted to ...
(do_test): ... this.
(TEST_FUNCTION): New macro.
Include test-skeleton.c.
* setjmp/tst-setjmp.c (main): Converted to ...
(do_test): ... this.
(TEST_FUNCTION): New macro.
Include test-skeleton.c.
* stdio-common/tst-sscanf.c (main): Converted to ...
(do_test): ... this.
(TEST_FUNCTION): New macro.
Include test-skeleton.c.
* sysdeps/x86_64/tst-audit6.c (main): Converted to ...
(do_test): ... this.
(TEST_FUNCTION): New macro.
Include test-skeleton.c.
This test was skipped by the use-test-skeleton conversion script
[29955b5d] because the definition of `main' did not begin according to
the GNU formatting style that the script assumed.
ChangeLog:
2015-07-09 Arjun Shankar <arjun.is@lostca.se>
* elf/tst-audit9.c (main): Converted to ...
(do_test): ... this.
(TEST_FUNCTION): New macro.
Include test-skeleton.c.
The testcase stdlib/tst-makecontext fails on i686 because
_Unwind_Backtrace from libgcc produces a segmentation fault if it was
called within a context created by makecontext. See Bug 18635.
ChangeLog:
* sysdeps/i386/i686/Makefile (test-xfail-tst-makecontext):
New variable.
Chung-Lin Tang