arm_pmu: Tidy up clear_event_idx call backs
The armpmu uses get_event_idx callback to allocate an event
counter for a given event, which marks the selected counter
as "used". Now, when we delete the counter, the arm_pmu goes
ahead and clears the "used" bit and then invokes the "clear_event_idx"
call back, which kind of splits the job between the core code
and the backend. To keep things tidy, mandate the implementation
of clear_event_idx() and add it for exisiting backends.
This will be useful for adding the chained event support, where
we leave the event idx maintenance to the backend.
Also, when an event is removed from the PMU, reset the hw.idx
to indicate that a counter is not allocated for this event,
to help the backends do better checks. This will be also used
for the chain counter support.
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 66a2ffd..ac66851 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -778,6 +778,12 @@ static int armv8pmu_get_event_idx(struct pmu_hw_events *cpuc,
return -EAGAIN;
}
+static void armv8pmu_clear_event_idx(struct pmu_hw_events *cpuc,
+ struct perf_event *event)
+{
+ clear_bit(event->hw.idx, cpuc->used_mask);
+}
+
/*
* Add an event filter to a given event. This will only work for PMUv2 PMUs.
*/
@@ -956,6 +962,7 @@ static int armv8_pmu_init(struct arm_pmu *cpu_pmu)
cpu_pmu->read_counter = armv8pmu_read_counter,
cpu_pmu->write_counter = armv8pmu_write_counter,
cpu_pmu->get_event_idx = armv8pmu_get_event_idx,
+ cpu_pmu->clear_event_idx = armv8pmu_clear_event_idx,
cpu_pmu->start = armv8pmu_start,
cpu_pmu->stop = armv8pmu_stop,
cpu_pmu->reset = armv8pmu_reset,