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65810f0ef0
glibc/sysdeps/nptl
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Torvald Riegel 65810f0ef0 robust mutexes: Fix broken x86 assembly by removing it 
lll_robust_unlock on i386 and x86_64 first sets the futex word to
FUTEX_WAITERS|0 before calling __lll_unlock_wake, which will set the
futex word to 0.  If the thread is killed between these steps, then the
futex word will be FUTEX_WAITERS|0, and the kernel (at least current
upstream) will not set it to FUTEX_OWNER_DIED|FUTEX_WAITERS because 0 is
not equal to the TID of the crashed thread.

The lll_robust_lock assembly code on i386 and x86_64 is not prepared to
deal with this case because the fastpath tries to only CAS 0 to TID and
not FUTEX_WAITERS|0 to TID; the slowpath simply waits until it can CAS 0
to TID or the futex_word has the FUTEX_OWNER_DIED bit set.

This issue is fixed by removing the custom x86 assembly code and using
the generic C code instead.  However, instead of adding more duplicate
code to the custom x86 lowlevellock.h, the code of the lll_robust* functions
is inlined into the single call sites that exist for each of these functions
in the pthread_mutex_* functions.  The robust mutex paths in the latter
have been slightly reorganized to make them simpler.

This patch is meant to be easy to backport, so C11-style atomics are not
used.

	[BZ #20985]
	* nptl/Makefile: Adapt.
	* nptl/pthread_mutex_cond_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove.
	(LLL_ROBUST_MUTEX_LOCK_MODIFIER): New.
	* nptl/pthread_mutex_lock.c (LLL_ROBUST_MUTEX_LOCK): Remove.
	(LLL_ROBUST_MUTEX_LOCK_MODIFIER): New.
	(__pthread_mutex_lock_full): Inline lll_robust* functions and adapt.
	* nptl/pthread_mutex_timedlock.c (pthread_mutex_timedlock): Inline
	lll_robust* functions and adapt.
	* nptl/pthread_mutex_unlock.c (__pthread_mutex_unlock_full): Likewise.
	* sysdeps/nptl/lowlevellock.h (__lll_robust_lock_wait,
	__lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait,
	__lll_robust_timedlock, __lll_robust_unlock): Remove.
	* sysdeps/unix/sysv/linux/i386/lowlevellock.h (lll_robust_lock,
	lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove.
	* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h (lll_robust_lock,
	lll_robust_cond_lock, lll_robust_timedlock, lll_robust_unlock): Remove.
	* sysdeps/unix/sysv/linux/sparc/lowlevellock.h (__lll_robust_lock_wait,
	__lll_robust_lock, lll_robust_cond_lock, __lll_robust_timedlock_wait,
	__lll_robust_timedlock, __lll_robust_unlock): Remove.
	* nptl/lowlevelrobustlock.c: Remove file.
	* nptl/lowlevelrobustlock.sym: Likewise.
	* sysdeps/unix/sysv/linux/i386/lowlevelrobustlock.S: Likewise.
	* sysdeps/unix/sysv/linux/x86_64/lowlevelrobustlock.S: Likewise.
2017-01-13 17:16:07 +01:00
..
sys Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
aio_misc.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
allocrtsig.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fork.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
fork.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
futex-internal.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
gai_misc.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
Implies
internaltypes.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
jmp-unwind.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
libc-lock.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
libc-lockP.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
librt-cancellation.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
lowlevellock-futex.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
lowlevellock.h robust mutexes: Fix broken x86 assembly by removing it 2017-01-13 17:16:07 +01:00
Makeconfig Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
Makefile Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
malloc-machine.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
nptl-signals.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
pthread-functions.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
pthread.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
setxid.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
shm-directory.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
sigfillset.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
stdio-lock.h Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00
Subdirs
tcb-offsets.h
tst-mqueue8x.c
unwind-forcedunwind.c Update copyright dates with scripts/update-copyrights. 2017-01-01 00:14:16 +00:00