| From | Luis Henriques <> | Subject | [PATCH 104/115] ARM: 7720/1: ARM v6/v7 cmpxchg64 shouldn't clear upper 32 bits of the old/new value | Date | Mon, 20 May 2013 11:51:44 +0100 |
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3.5.7.13 -stable review patch. If anyone has any objections, please let me know.
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From: Jaccon Bastiaansen <jaccon.bastiaansen@gmail.com>
commit 6eabb3301b1facee669d9938f7c5a0295c21d71d upstream.
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 3e0f5a15f500 ("ARM: 7404/1: cmpxchg64: use atomic64 and local64 routines for cmpxchg64").
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> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- arch/arm/include/asm/cmpxchg.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/arm/include/asm/cmpxchg.h b/arch/arm/include/asm/cmpxchg.h index 7eb18c1..4f009c1 100644 --- a/arch/arm/include/asm/cmpxchg.h +++ b/arch/arm/include/asm/cmpxchg.h @@ -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 */ -- 1.8.1.2
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