ARM: perf: hook up perf_sample_event_took around pmu irq handling

Since we indirect all of our PMU IRQ handling through a dispatcher, it's
trivial to hook up perf_sample_event_took to prevent applications such
as oprofile from generating interrupt storms due to an unrealisticly
low sample period.

Reported-by: Robert Richter <rric@kernel.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

diff --git a/arch/arm/kernel/perf_event.c b/arch/arm/kernel/perf_event.c
index 361a1aa..a6bc431 100644 (file)
--- a/arch/arm/kernel/perf_event.c
+++ b/arch/arm/kernel/perf_event.c
@@ -302,6 +302,8 @@ static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
        struct arm_pmu *armpmu;
        struct platform_device *plat_device;
        struct arm_pmu_platdata *plat;
+       int ret;
+       u64 start_clock, finish_clock;
 
        if (irq_is_percpu(irq))
                dev = *(void **)dev;
@@ -309,10 +311,15 @@ static irqreturn_t armpmu_dispatch_irq(int irq, void *dev)
        plat_device = armpmu->plat_device;
        plat = dev_get_platdata(&plat_device->dev);
 
+       start_clock = sched_clock();
        if (plat && plat->handle_irq)
-               return plat->handle_irq(irq, dev, armpmu->handle_irq);
+               ret = plat->handle_irq(irq, dev, armpmu->handle_irq);
        else
-               return armpmu->handle_irq(irq, dev);
+               ret = armpmu->handle_irq(irq, dev);
+       finish_clock = sched_clock();
+
+       perf_sample_event_took(finish_clock - start_clock);
+       return ret;
 }
 
 static void