linux-kernel - [PATCH v4 2/5] perf arm-spe: Calculate meta data size

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Message-Id: <20241003184302.190806-3-leo.yan@arm.com>
Date: Thu,  3 Oct 2024 19:42:59 +0100
From: Leo Yan <leo.yan@....com>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	Besar Wicaksono <bwicaksono@...dia.com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Will Deacon <will@...nel.org>,
	John Garry <john.g.garry@...cle.com>,
	James Clark <james.clark@...aro.org>,
	Mike Leach <mike.leach@...aro.org>
Cc: Leo Yan <leo.yan@....com>
Subject: [PATCH v4 2/5] perf arm-spe: Calculate meta data size

The metadata is designed to contain a header and per CPU information.

The arm_spe_find_cpus() function is introduced to identify how many CPUs
support ARM SPE. Based on the CPU number, calculates the metadata size.

Signed-off-by: Leo Yan <leo.yan@....com>
Reviewed-by: James Clark <james.clark@...aro.org>
---
 tools/perf/arch/arm64/util/arm-spe.c | 39 +++++++++++++++++++++++++---
 1 file changed, 36 insertions(+), 3 deletions(-)

diff --git a/tools/perf/arch/arm64/util/arm-spe.c b/tools/perf/arch/arm64/util/arm-spe.c
index c2d5c8ca4900..81d5c07380a4 100644
--- a/tools/perf/arch/arm64/util/arm-spe.c
+++ b/tools/perf/arch/arm64/util/arm-spe.c
@@ -37,11 +37,44 @@ struct arm_spe_recording {
 	bool			*wrapped;
 };
 
+/*
+ * arm_spe_find_cpus() returns a new cpu map, and the caller should invoke
+ * perf_cpu_map__put() to release the map after use.
+ */
+static struct perf_cpu_map *arm_spe_find_cpus(struct evlist *evlist)
+{
+	struct perf_cpu_map *event_cpus = evlist->core.user_requested_cpus;
+	struct perf_cpu_map *online_cpus = perf_cpu_map__new_online_cpus();
+	struct perf_cpu_map *intersect_cpus;
+
+	/* cpu map is not "any" CPU , we have specific CPUs to work with */
+	if (!perf_cpu_map__has_any_cpu(event_cpus)) {
+		intersect_cpus = perf_cpu_map__intersect(event_cpus, online_cpus);
+		perf_cpu_map__put(online_cpus);
+	/* Event can be "any" CPU so count all CPUs. */
+	} else {
+		intersect_cpus = online_cpus;
+	}
+
+	return intersect_cpus;
+}
+
 static size_t
 arm_spe_info_priv_size(struct auxtrace_record *itr __maybe_unused,
-		       struct evlist *evlist __maybe_unused)
+		       struct evlist *evlist)
 {
-	return ARM_SPE_AUXTRACE_V1_PRIV_SIZE;
+	struct perf_cpu_map *cpu_map = arm_spe_find_cpus(evlist);
+	size_t size;
+
+	if (!cpu_map)
+		return 0;
+
+	size = ARM_SPE_AUXTRACE_PRIV_MAX +
+	       ARM_SPE_CPU_PRIV_MAX * perf_cpu_map__nr(cpu_map);
+	size *= sizeof(u64);
+
+	perf_cpu_map__put(cpu_map);
+	return size;
 }
 
 static int arm_spe_info_fill(struct auxtrace_record *itr,
@@ -53,7 +86,7 @@ static int arm_spe_info_fill(struct auxtrace_record *itr,
 			container_of(itr, struct arm_spe_recording, itr);
 	struct perf_pmu *arm_spe_pmu = sper->arm_spe_pmu;
 
-	if (priv_size != ARM_SPE_AUXTRACE_V1_PRIV_SIZE)
+	if (priv_size != arm_spe_info_priv_size(itr, session->evlist))
 		return -EINVAL;
 
 	if (!session->evlist->core.nr_mmaps)
-- 
2.34.1