Commit 8b8ff8cc authored by Adrian Hunter's avatar Adrian Hunter Committed by Peter Zijlstra
Browse files

perf/x86: Add new event for AUX output counter index 



PEBS-via-PT records contain a mask of applicable counters. To identify
which event belongs to which counter, a side-band event is needed. Until
now, there has been no side-band event, and consequently users were limited
to using a single event.

Add such a side-band event. Note the event is optimised to output only
when the counter index changes for an event. That works only so long as
all PEBS-via-PT events are scheduled together, which they are for a
recording session because they are in a single group.

Also no attribute bit is used to select the new event, so a new
kernel is not compatible with older perf tools.  The assumption
being that PEBS-via-PT is sufficiently esoteric that users will not
be troubled by this.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210907163903.11820-2-adrian.hunter@intel.com
parent 41100833

arch/x86/events/core.c

+6 −0
Original line number Diff line number Diff line
@@ -66,6 +66,8 @@ DEFINE_STATIC_CALL_NULL(x86_pmu_enable_all, *x86_pmu.enable_all); 
DEFINE_STATIC_CALL_NULL(x86_pmu_enable,	     *x86_pmu.enable);

DEFINE_STATIC_CALL_NULL(x86_pmu_disable,     *x86_pmu.disable);



DEFINE_STATIC_CALL_NULL(x86_pmu_assign, *x86_pmu.assign);



DEFINE_STATIC_CALL_NULL(x86_pmu_add,  *x86_pmu.add);

DEFINE_STATIC_CALL_NULL(x86_pmu_del,  *x86_pmu.del);

DEFINE_STATIC_CALL_NULL(x86_pmu_read, *x86_pmu.read);
@@ -1215,6 +1217,8 @@ static inline void x86_assign_hw_event(struct perf_event *event, 
	hwc->last_cpu = smp_processor_id();

	hwc->last_tag = ++cpuc->tags[i];



	static_call_cond(x86_pmu_assign)(event, idx);



	switch (hwc->idx) {

	case INTEL_PMC_IDX_FIXED_BTS:

	case INTEL_PMC_IDX_FIXED_VLBR:
@@ -2005,6 +2009,8 @@ static void x86_pmu_static_call_update(void) 
	static_call_update(x86_pmu_enable, x86_pmu.enable);

	static_call_update(x86_pmu_disable, x86_pmu.disable);



	static_call_update(x86_pmu_assign, x86_pmu.assign);



	static_call_update(x86_pmu_add, x86_pmu.add);

	static_call_update(x86_pmu_del, x86_pmu.del);

	static_call_update(x86_pmu_read, x86_pmu.read);

arch/x86/events/intel/core.c

+16 −0
Original line number Diff line number Diff line
@@ -2402,6 +2402,12 @@ static void intel_pmu_disable_event(struct perf_event *event) 
		intel_pmu_pebs_disable(event);

}



static void intel_pmu_assign_event(struct perf_event *event, int idx)

{

	if (is_pebs_pt(event))

		perf_report_aux_output_id(event, idx);

}



static void intel_pmu_del_event(struct perf_event *event)

{

	if (needs_branch_stack(event))
@@ -4494,8 +4500,16 @@ static int intel_pmu_check_period(struct perf_event *event, u64 value) 
	return intel_pmu_has_bts_period(event, value) ? -EINVAL : 0;

}



static void intel_aux_output_init(void)

{

	/* Refer also intel_pmu_aux_output_match() */

	if (x86_pmu.intel_cap.pebs_output_pt_available)

		x86_pmu.assign = intel_pmu_assign_event;

}



static int intel_pmu_aux_output_match(struct perf_event *event)

{

	/* intel_pmu_assign_event() is needed, refer intel_aux_output_init() */

	if (!x86_pmu.intel_cap.pebs_output_pt_available)

		return 0;
@@ -6301,6 +6315,8 @@ __init int intel_pmu_init(void) 
	if (is_hybrid())

		intel_pmu_check_hybrid_pmus((u64)fixed_mask);



	intel_aux_output_init();



	return 0;

}

arch/x86/events/perf_event.h

+1 −0
Original line number Diff line number Diff line
@@ -726,6 +726,7 @@ struct x86_pmu { 
	void		(*enable_all)(int added);

	void		(*enable)(struct perf_event *);

	void		(*disable)(struct perf_event *);

	void		(*assign)(struct perf_event *event, int idx);

	void		(*add)(struct perf_event *);

	void		(*del)(struct perf_event *);

	void		(*read)(struct perf_event *event);

include/linux/perf_event.h

+1 −0
Original line number Diff line number Diff line
@@ -1397,6 +1397,7 @@ perf_event_addr_filters(struct perf_event *event) 
}



extern void perf_event_addr_filters_sync(struct perf_event *event);

extern void perf_report_aux_output_id(struct perf_event *event, u64 hw_id);



extern int perf_output_begin(struct perf_output_handle *handle,

			     struct perf_sample_data *data,

include/uapi/linux/perf_event.h

+15 −0
Original line number Diff line number Diff line
@@ -1141,6 +1141,21 @@ enum perf_event_type { 
	 */

	PERF_RECORD_TEXT_POKE			= 20,



	/*

	 * Data written to the AUX area by hardware due to aux_output, may need

	 * to be matched to the event by an architecture-specific hardware ID.

	 * This records the hardware ID, but requires sample_id to provide the

	 * event ID. e.g. Intel PT uses this record to disambiguate PEBS-via-PT

	 * records from multiple events.

	 *

	 * struct {

	 *	struct perf_event_header	header;

	 *	u64				hw_id;

	 *	struct sample_id		sample_id;

	 * };

	 */

	PERF_RECORD_AUX_OUTPUT_HW_ID		= 21,



	PERF_RECORD_MAX,			/* non-ABI */

};