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ARM: 7355/1: perf: clear overflow flag when disabling counter on ARMv7 PMU 

When disabling a counter on an ARMv7 PMU, we should also clear the
overflow flag in case an overflow occurred whilst stopping the counter.
This prevents a spurious overflow being picked up later and leading to
either false accounting or a NULL dereference.

Cc: <stable@vger.kernel.org>
Reported-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Will Deacon 2012-03-06 17:34:22 +01:00 committed by Russell King
parent 5727347180
commit 99c1745b9c
1 changed files with 5 additions and 0 deletions
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5
arch/arm/kernel/perf_event_v7.c
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@ -809,6 +809,11 @@ static inline int armv7_pmnc_disable_intens(int idx)
counter = ARMV7_IDX_TO_COUNTER(idx);
asm volatile("mcr p15, 0, %0, c9, c14, 2" : : "r" (BIT(counter)));
isb();
/* Clear the overflow flag in case an interrupt is pending. */
asm volatile("mcr p15, 0, %0, c9, c12, 3" : : "r" (BIT(counter)));
isb();
return idx;
}