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Commit eab443ef authored by Stephen Boyd's avatar Stephen Boyd Committed by Will Deacon
Browse files

ARM: perf: add hook for event index clearing 



On Krait processors we have a many-to-one relationship between
raw CPU events and the event programmed into the PMNx counter.
Two raw CPU events could map to the same value programmed in the
PMNx counter. To avoid this problem, we check for collisions
during the get_event_idx() callback by setting a bit in a bitmap
whenever a certain event is used in a PMNx counter (see the next
patch). Unfortunately, we don't have a hook to clear this bit in
the bitmap when the event is deleted so let's add an optional
clear_event_idx() callback for this purpose.

Signed-off-by: default avatarStephen Boyd <sboyd@codeaurora.org>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 2a3391cd

arch/arm/include/asm/pmu.h

+2 −0
Original line number Diff line number Diff line
@@ -71,6 +71,8 @@ struct arm_pmu { 
	void		(*disable)(struct perf_event *event);

	int		(*get_event_idx)(struct pmu_hw_events *hw_events,

					 struct perf_event *event);

	void		(*clear_event_idx)(struct pmu_hw_events *hw_events,

					 struct perf_event *event);

	int		(*set_event_filter)(struct hw_perf_event *evt,

					    struct perf_event_attr *attr);

	u32		(*read_counter)(struct perf_event *event);

arch/arm/kernel/perf_event.c

+2 −0
Original line number Diff line number Diff line
@@ -207,6 +207,8 @@ armpmu_del(struct perf_event *event, int flags) 
	armpmu_stop(event, PERF_EF_UPDATE);

	hw_events->events[idx] = NULL;

	clear_bit(idx, hw_events->used_mask);

	if (armpmu->clear_event_idx)

		armpmu->clear_event_idx(hw_events, event);



	perf_event_update_userpage(event);

}