linux-kernel - [PATCH v2] perf arm-spe: Synthesize SPE instruction events

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Message-Id: <20211215184605.92787-1-german.gomez@arm.com>
Date:   Wed, 15 Dec 2021 18:46:05 +0000
From:   German Gomez <german.gomez@....com>
To:     linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        acme@...nel.org
Cc:     German Gomez <german.gomez@....com>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: [PATCH v2] perf arm-spe: Synthesize SPE instruction events

Synthesize instruction events per every decoded ARM SPE record.

Because Arm SPE implements a hardware-based sample period, and perf
implements a software-based one that gets applied on top, also add a
warning to make the user aware.

Signed-off-by: German Gomez <german.gomez@....com>
---
Changes since v1 [https://lore.kernel.org/all/20211117142833.226629-1-german.gomez@arm.com]
  - Generate events with "--itrace=i" instead of "--itrace=o".
  - Generate events with virt_addr, phys_addr, and data_src values.
---
 tools/perf/util/arm-spe.c | 58 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/tools/perf/util/arm-spe.c b/tools/perf/util/arm-spe.c
index fccac06b573a..879583822c8f 100644
--- a/tools/perf/util/arm-spe.c
+++ b/tools/perf/util/arm-spe.c
@@ -58,6 +58,8 @@ struct arm_spe {
 	u8				sample_branch;
 	u8				sample_remote_access;
 	u8				sample_memory;
+	u8				sample_instructions;
+	u64				instructions_sample_period;
 
 	u64				l1d_miss_id;
 	u64				l1d_access_id;
@@ -68,6 +70,7 @@ struct arm_spe {
 	u64				branch_miss_id;
 	u64				remote_access_id;
 	u64				memory_id;
+	u64				instructions_id;
 
 	u64				kernel_start;
 
@@ -90,6 +93,7 @@ struct arm_spe_queue {
 	u64				time;
 	u64				timestamp;
 	struct thread			*thread;
+	u64				period_instructions;
 };
 
 static void arm_spe_dump(struct arm_spe *spe __maybe_unused,
@@ -202,6 +206,7 @@ static struct arm_spe_queue *arm_spe__alloc_queue(struct arm_spe *spe,
 	speq->pid = -1;
 	speq->tid = -1;
 	speq->cpu = -1;
+	speq->period_instructions = 0;
 
 	/* params set */
 	params.get_trace = arm_spe_get_trace;
@@ -351,6 +356,33 @@ static int arm_spe__synth_branch_sample(struct arm_spe_queue *speq,
 	return arm_spe_deliver_synth_event(spe, speq, event, &sample);
 }
 
+static int arm_spe__synth_instruction_sample(struct arm_spe_queue *speq,
+					     u64 spe_events_id, u64 data_src)
+{
+	struct arm_spe *spe = speq->spe;
+	struct arm_spe_record *record = &speq->decoder->record;
+	union perf_event *event = speq->event_buf;
+	struct perf_sample sample = { .ip = 0, };
+
+	/*
+	 * Handles perf instruction sampling period.
+	 */
+	speq->period_instructions++;
+	if (speq->period_instructions < spe->instructions_sample_period)
+		return 0;
+	speq->period_instructions = 0;
+
+	arm_spe_prep_sample(spe, speq, event, &sample);
+
+	sample.id = spe_events_id;
+	sample.stream_id = spe_events_id;
+	sample.addr = record->virt_addr;
+	sample.phys_addr = record->phys_addr;
+	sample.data_src = data_src;
+
+	return arm_spe_deliver_synth_event(spe, speq, event, &sample);
+}
+
 #define SPE_MEM_TYPE	(ARM_SPE_L1D_ACCESS | ARM_SPE_L1D_MISS | \
 			 ARM_SPE_LLC_ACCESS | ARM_SPE_LLC_MISS | \
 			 ARM_SPE_REMOTE_ACCESS)
@@ -480,6 +512,12 @@ static int arm_spe_sample(struct arm_spe_queue *speq)
 			return err;
 	}
 
+	if (spe->sample_instructions) {
+		err = arm_spe__synth_instruction_sample(speq, spe->instructions_id, data_src);
+		if (err)
+			return err;
+	}
+
 	return 0;
 }
 
@@ -1107,6 +1145,26 @@ arm_spe_synth_events(struct arm_spe *spe, struct perf_session *session)
 			return err;
 		spe->memory_id = id;
 		arm_spe_set_event_name(evlist, id, "memory");
+		id += 1;
+	}
+
+	if (spe->synth_opts.instructions) {
+		if (spe->synth_opts.period_type != PERF_ITRACE_PERIOD_INSTRUCTIONS)
+			return -EINVAL;
+
+		if (spe->synth_opts.period > 1)
+			pr_warning("Arm SPE has a hardware-based sample period.\n"
+				   "More instruction events will be discarded by --itrace\n");
+
+		spe->sample_instructions = true;
+		attr.config = PERF_COUNT_HW_INSTRUCTIONS;
+		attr.sample_period = spe->synth_opts.period;
+		spe->instructions_sample_period = attr.sample_period;
+		err = arm_spe_synth_event(session, &attr, id);
+		if (err)
+			return err;
+		spe->instructions_id = id;
+		arm_spe_set_event_name(evlist, id, "instructions");
 	}
 
 	return 0;
-- 
2.25.1