perf intel-pt: Add support for PERF_RECORD_AUX_OUTPUT_HW_ID

Originally, software only supported redirecting at most one PEBS event to
Intel PT (PEBS-via-PT) because it was not able to differentiate one event
from another. To overcome that, add support for the
PERF_RECORD_AUX_OUTPUT_HW_ID side-band event.

Committer notes:

Cast the pointer arg to for_each_set_bit() to (unsigned long *), to fix
the build on 32-bit systems.

Reviewed-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: x86@kernel.org
Link: http://lore.kernel.org/lkml/20210907163903.11820-4-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-intel-pt.txt

@@ -1144,7 +1144,12 @@ Recording is selected by using the aux-output config term e.g.
 
 	perf record -c 10000 -e '{intel_pt/branch=0/,cycles/aux-output/ppp}' uname
 
-Note that currently, software only supports redirecting at most one PEBS event.
+Originally, software only supported redirecting at most one PEBS event because it
+was not able to differentiate one event from another. To overcome that, more recent
+kernels and perf tools add support for the PERF_RECORD_AUX_OUTPUT_HW_ID side-band event.
+To check for the presence of that event in a PEBS-via-PT trace:
+
+	perf script -D --no-itrace | grep PERF_RECORD_AUX_OUTPUT_HW_ID
 
 To display PEBS events from the Intel PT trace, use the itrace 'o' option e.g.
 

tools/perf/util/intel-pt.c

@@ -111,6 +111,7 @@ struct intel_pt {
 	u64 cbr_id;
 	u64 psb_id;
 
+	bool single_pebs;
 	bool sample_pebs;
 	struct evsel *pebs_evsel;
 
@@ -148,6 +149,14 @@ enum switch_state {
 	INTEL_PT_SS_EXPECTING_SWITCH_IP,
 };
 
+/* applicable_counters is 64-bits */
+#define INTEL_PT_MAX_PEBS 64
+
+struct intel_pt_pebs_event {
+	struct evsel *evsel;
+	u64 id;
+};
+
 struct intel_pt_queue {
 	struct intel_pt *pt;
 	unsigned int queue_nr;
@@ -189,6 +198,7 @@ struct intel_pt_queue {
 	u64 last_br_cyc_cnt;
 	unsigned int cbr_seen;
 	char insn[INTEL_PT_INSN_BUF_SZ];
+	struct intel_pt_pebs_event pebs[INTEL_PT_MAX_PEBS];
 };
 
 static void intel_pt_dump(struct intel_pt *pt __maybe_unused,
@@ -1978,15 +1988,13 @@ static void intel_pt_add_lbrs(struct branch_stack *br_stack,
 	}
 }
 
-static int intel_pt_synth_pebs_sample(struct intel_pt_queue *ptq)
+static int intel_pt_do_synth_pebs_sample(struct intel_pt_queue *ptq, struct evsel *evsel, u64 id)
 {
 	const struct intel_pt_blk_items *items = &ptq->state->items;
 	struct perf_sample sample = { .ip = 0, };
 	union perf_event *event = ptq->event_buf;
 	struct intel_pt *pt = ptq->pt;
-	struct evsel *evsel = pt->pebs_evsel;
 	u64 sample_type = evsel->core.attr.sample_type;
-	u64 id = evsel->core.id[0];
 	u8 cpumode;
 	u64 regs[8 * sizeof(sample.intr_regs.mask)];
 
@@ -2112,6 +2120,45 @@ static int intel_pt_synth_pebs_sample(struct intel_pt_queue *ptq)
 	return intel_pt_deliver_synth_event(pt, event, &sample, sample_type);
 }
 
+static int intel_pt_synth_single_pebs_sample(struct intel_pt_queue *ptq)
+{
+	struct intel_pt *pt = ptq->pt;
+	struct evsel *evsel = pt->pebs_evsel;
+	u64 id = evsel->core.id[0];
+
+	return intel_pt_do_synth_pebs_sample(ptq, evsel, id);
+}
+
+static int intel_pt_synth_pebs_sample(struct intel_pt_queue *ptq)
+{
+	const struct intel_pt_blk_items *items = &ptq->state->items;
+	struct intel_pt_pebs_event *pe;
+	struct intel_pt *pt = ptq->pt;
+	int err = -EINVAL;
+	int hw_id;
+
+	if (!items->has_applicable_counters || !items->applicable_counters) {
+		if (!pt->single_pebs)
+			pr_err("PEBS-via-PT record with no applicable_counters\n");
+		return intel_pt_synth_single_pebs_sample(ptq);
+	}
+
+	for_each_set_bit(hw_id, (unsigned long *)&items->applicable_counters, INTEL_PT_MAX_PEBS) {
+		pe = &ptq->pebs[hw_id];
+		if (!pe->evsel) {
+			if (!pt->single_pebs)
+				pr_err("PEBS-via-PT record with no matching event, hw_id %d\n",
+				       hw_id);
+			return intel_pt_synth_single_pebs_sample(ptq);
+		}
+		err = intel_pt_do_synth_pebs_sample(ptq, pe->evsel, pe->id);
+		if (err)
+			return err;
+	}
+
+	return err;
+}
+
 static int intel_pt_synth_error(struct intel_pt *pt, int code, int cpu,
 				pid_t pid, pid_t tid, u64 ip, u64 timestamp)
 {
@@ -2882,6 +2929,30 @@ static int intel_pt_process_itrace_start(struct intel_pt *pt,
 					event->itrace_start.tid);
 }
 
+static int intel_pt_process_aux_output_hw_id(struct intel_pt *pt,
+					     union perf_event *event,
+					     struct perf_sample *sample)
+{
+	u64 hw_id = event->aux_output_hw_id.hw_id;
+	struct auxtrace_queue *queue;
+	struct intel_pt_queue *ptq;
+	struct evsel *evsel;
+
+	queue = auxtrace_queues__sample_queue(&pt->queues, sample, pt->session);
+	evsel = evlist__id2evsel_strict(pt->session->evlist, sample->id);
+	if (!queue || !queue->priv || !evsel || hw_id > INTEL_PT_MAX_PEBS) {
+		pr_err("Bad AUX output hardware ID\n");
+		return -EINVAL;
+	}
+
+	ptq = queue->priv;
+
+	ptq->pebs[hw_id].evsel = evsel;
+	ptq->pebs[hw_id].id = sample->id;
+
+	return 0;
+}
+
 static int intel_pt_find_map(struct thread *thread, u8 cpumode, u64 addr,
 			     struct addr_location *al)
 {
@@ -3009,6 +3080,8 @@ static int intel_pt_process_event(struct perf_session *session,
 		err = intel_pt_process_switch(pt, sample);
 	else if (event->header.type == PERF_RECORD_ITRACE_START)
 		err = intel_pt_process_itrace_start(pt, event, sample);
+	else if (event->header.type == PERF_RECORD_AUX_OUTPUT_HW_ID)
+		err = intel_pt_process_aux_output_hw_id(pt, event, sample);
 	else if (event->header.type == PERF_RECORD_SWITCH ||
 		 event->header.type == PERF_RECORD_SWITCH_CPU_WIDE)
 		err = intel_pt_context_switch(pt, event, sample);
@@ -3393,9 +3466,13 @@ static void intel_pt_setup_pebs_events(struct intel_pt *pt)
 
 	evlist__for_each_entry(pt->session->evlist, evsel) {
 		if (evsel->core.attr.aux_output && evsel->core.id) {
+			if (pt->single_pebs) {
+				pt->single_pebs = false;
+				return;
+			}
+			pt->single_pebs = true;
 			pt->sample_pebs = true;
 			pt->pebs_evsel = evsel;
-			return;
 		}
 	}
 }