ARM: 6352/1: perf: fix event validation

The validate_event function in the ARM perf events backend has the
following problems:

1.) Events that are disabled count towards the cost.
2.) Events associated with other PMUs [for example, software events or
    breakpoints] do not count towards the cost, but do fail validation,
    causing the group to fail.

This patch changes validate_event so that it ignores events in the
PERF_EVENT_STATE_OFF state or that are scheduled for other PMUs.
Reported-by: NPawel Moll <pawel.moll@arm.com>
Acked-by: NJamie Iles <jamie.iles@picochip.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/perf_event.c

@@ -319,8 +319,8 @@ validate_event(struct cpu_hw_events *cpuc,
 {
 	struct hw_perf_event fake_event = event->hw;
 
-	if (event->pmu && event->pmu != &pmu)
-		return 0;
+	if (event->pmu != &pmu || event->state <= PERF_EVENT_STATE_OFF)
+		return 1;
 
 	return armpmu->get_event_idx(cpuc, &fake_event) >= 0;
 }