From 99c1745b9c76910e195889044f914b4898b7c9a5 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Tue, 6 Mar 2012 17:34:22 +0100 Subject: [PATCH] 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: Reported-by: Ming Lei Signed-off-by: Will Deacon Signed-off-by: Russell King --- arch/arm/kernel/perf_event_v7.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/arm/kernel/perf_event_v7.c b/arch/arm/kernel/perf_event_v7.c index 6f488610f8f..050cc8bf724 100644 --- a/arch/arm/kernel/perf_event_v7.c +++ b/arch/arm/kernel/perf_event_v7.c @@ -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; } -- 2.39.2