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git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
[PATCH] fix i386 mutex fastpath on FRAME_POINTER && !DEBUG_MUTEXES
Call the mutex slowpath more conservatively - e.g. FRAME_POINTERS can
change the calling convention, in which case a direct branch to the
slowpath becomes illegal. Bug found by Hugh Dickins.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
authored by
Ingo Molnar
and committed by
Linus Torvalds
73165b88
042c904c
+14
-2
include/asm-i386/mutex.h
+14
-2
include/asm-i386/mutex.h
···
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\
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__asm__ __volatile__( \
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LOCK " decl (%%eax) \n" \
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-
" js "#fail_fn" \n" \
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" js 2f \n" \
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"1: \n" \
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\
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LOCK_SECTION_START("") \
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"2: call "#fail_fn" \n" \
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" jmp 1b \n" \
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LOCK_SECTION_END \
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\
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:"=a" (dummy) \
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: "a" (count) \
···
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\
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__asm__ __volatile__( \
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LOCK " incl (%%eax) \n" \
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" jle "#fail_fn" \n" \
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" jle 2f \n" \
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"1: \n" \
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\
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LOCK_SECTION_START("") \
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"2: call "#fail_fn" \n" \
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" jmp 1b \n" \
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LOCK_SECTION_END \
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\
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:"=a" (dummy) \
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: "a" (count) \
-9
kernel/mutex.c
-9
kernel/mutex.c
···
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/*
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* The locking fastpath is the 1->0 transition from
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* 'unlocked' into 'locked' state.
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*
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* NOTE: if asm/mutex.h is included, then some architectures
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* rely on mutex_lock() having _no other code_ here but this
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* fastpath. That allows the assembly fastpath to do
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* tail-merging optimizations. (If you want to put testcode
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* here, do it under #ifndef CONFIG_MUTEX_DEBUG.)
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*/
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__mutex_fastpath_lock(&lock->count, __mutex_lock_slowpath);
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}
···
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/*
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* The unlocking fastpath is the 0->1 transition from 'locked'
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* into 'unlocked' state:
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*
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* NOTE: no other code must be here - see mutex_lock() .
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*/
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__mutex_fastpath_unlock(&lock->count, __mutex_unlock_slowpath);
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}
···
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*/
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int fastcall __sched mutex_lock_interruptible(struct mutex *lock)
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{
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/* NOTE: no other code must be here - see mutex_lock() */
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return __mutex_fastpath_lock_retval
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(&lock->count, __mutex_lock_interruptible_slowpath);
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}