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ARM: 7720/1: ARM v6/v7 cmpxchg64 shouldn't clear upper 32 bits of the old/new value

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The implementation of cmpxchg64() for the ARM v6 and v7 architecture
casts parameter 2 and 3 (the old and new 64bit values) to an unsigned
long before calling the atomic_cmpxchg64() function. This clears
the top 32 bits of the old and new values, resulting in the wrong
values being compare-exchanged. Luckily, this only appears to be used
for 64-bit sched_clock, which we don't (yet) have on ARM.

This bug was introduced by commit 3e0f5a15f5 ("ARM: 7404/1: cmpxchg64:
use atomic64 and local64 routines for cmpxchg64").

Cc: <stable@vger.kernel.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jaccon Bastiaansen <jaccon.bastiaansen@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Jaccon Bastiaansen 2013-05-13 17:28:27 +01:00 committed by Russell King
parent 9e01573b5c
commit 6eabb3301b
1 changed files with 4 additions and 4 deletions
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8
arch/arm/include/asm/cmpxchg.h
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@ -233,15 +233,15 @@ static inline unsigned long __cmpxchg_local(volatile void *ptr,
((__typeof__(*(ptr)))atomic64_cmpxchg(container_of((ptr), \
atomic64_t, \
counter), \
(unsigned long)(o), \
(unsigned long)(n)))
(unsigned long long)(o), \
(unsigned long long)(n)))
#define cmpxchg64_local(ptr, o, n) \
((__typeof__(*(ptr)))local64_cmpxchg(container_of((ptr), \
local64_t, \
a), \
(unsigned long)(o), \
(unsigned long)(n)))
(unsigned long long)(o), \
(unsigned long long)(n)))
#endif /* __LINUX_ARM_ARCH__ >= 6 */