linux-kernel - [PATCH v2 3/4] perf arm-spe: Enable timestamp for per-cpu mode

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Date:   Wed, 19 May 2021 12:15:45 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        John Garry <john.garry@...wei.com>,
        Will Deacon <will@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        James Clark <james.clark@....com>, Al Grant <Al.Grant@....com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v2 3/4] perf arm-spe: Enable timestamp for per-cpu mode

For per-cpu mmap, it should enable timestamp tracing for Arm SPE; this
is helpful for samples correlation.

To automatically enable the timestamp, a helper arm_spe_set_timestamp()
is introduced for setting "ts_enable" format bit.

Signed-off-by: Leo Yan <leo.yan@...aro.org>
Reviewed-by: James Clark <james.clark@....com>
Tested-by: James Clark <james.clark@....com>
---
 tools/perf/arch/arm64/util/arm-spe.c | 33 ++++++++++++++++++++++++++--
 1 file changed, 31 insertions(+), 2 deletions(-)

diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c
index 4c916626c203..bacdf366040d 100644
--- a/tools/perf/arch/arm64/util/arm-spe.c
+++ b/tools/perf/arch/arm64/util/arm-spe.c
@@ -14,6 +14,7 @@
 #include "../../../util/cpumap.h"
 #include "../../../util/event.h"
 #include "../../../util/evsel.h"
+#include "../../../util/evsel_config.h"
 #include "../../../util/evlist.h"
 #include "../../../util/session.h"
 #include <internal/lib.h> // page_size
@@ -32,6 +33,29 @@ struct arm_spe_recording {
 	struct evlist		*evlist;
 };
 
+static void arm_spe_set_timestamp(struct auxtrace_record *itr,
+				  struct evsel *evsel)
+{
+	struct arm_spe_recording *ptr;
+	struct perf_pmu *arm_spe_pmu;
+	struct evsel_config_term *term = evsel__get_config_term(evsel, CFG_CHG);
+	u64 user_bits = 0, bit;
+
+	ptr = container_of(itr, struct arm_spe_recording, itr);
+	arm_spe_pmu = ptr->arm_spe_pmu;
+
+	if (term)
+		user_bits = term->val.cfg_chg;
+
+	bit = perf_pmu__format_bits(&arm_spe_pmu->format, "ts_enable");
+
+	/* Skip if user has set it */
+	if (bit & user_bits)
+		return;
+
+	evsel->core.attr.config |= bit;
+}
+
 static size_t
 arm_spe_info_priv_size(struct auxtrace_record *itr __maybe_unused,
 		       struct evlist *evlist __maybe_unused)
@@ -121,9 +145,14 @@ static int arm_spe_recording_options(struct auxtrace_record *itr,
 	 */
 	evlist__to_front(evlist, arm_spe_evsel);
 
-	/* In the case of per-cpu mmaps, sample CPU for AUX event. */
-	if (!perf_cpu_map__empty(cpus))
+	/*
+	 * In the case of per-cpu mmaps, sample CPU for AUX event;
+	 * also enable the timestamp tracing for samples correlation.
+	 */
+	if (!perf_cpu_map__empty(cpus)) {
 		evsel__set_sample_bit(arm_spe_evsel, CPU);
+		arm_spe_set_timestamp(itr, arm_spe_evsel);
+	}
 
 	/* Add dummy event to keep tracking */
 	err = parse_events(evlist, "dummy:u", NULL);
-- 
2.25.1