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From: James Clark <james.clark@arm.com>
To: linux-perf-users@vger.kernel.org,
	coresight@lists.linaro.org
Cc: James Clark <james.clark@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Mike Leach <mike.leach@linaro.org>,
	John Garry <john.g.garry@oracle.com>,
	Will Deacon <will@kernel.org>,
	Leo Yan <leo.yan@linux.dev>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Namhyung Kim <namhyung@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>,
	Ian Rogers <irogers@google.com>,
	Adrian Hunter <adrian.hunter@intel.com>,
	"Liang, Kan" <kan.liang@linux.intel.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH] perf cs-etm: Improve version detection and error reporting
Date: Tue, 30 Apr 2024 14:32:21 +0100
Message-Id: <20240430133221.250811-1-james.clark@arm.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

When the config validation functions are warning about ETMv3, they do it
based on "not ETMv4". If the drivers aren't all loaded or the hardware
doesn't support Coresight it will appear as "not ETMv4" and then Perf
will print the error message "... not supported in ETMv3 ..." which is
wrong and confusing.

cs_etm_is_etmv4() is also misnamed because it also returns true for
ETE because ETE has a superset of the ETMv4 metadata files. Although
this was always done in the correct order so it wasn't a bug.

Improve all this by making a single get version function which also
handles not present as a separate case. Change the ETMv3 error message
to only print when ETMv3 is detected, and add a new error message for
the not present case.

Signed-off-by: James Clark <james.clark@arm.com>
---
 tools/perf/arch/arm/util/cs-etm.c | 64 +++++++++++++++++++++++--------
 1 file changed, 48 insertions(+), 16 deletions(-)

diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index 07be32d99805..2763c6758b91 100644
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -66,9 +66,25 @@ static const char * const metadata_ete_ro[] = {
 	[CS_ETE_TS_SOURCE]		= "ts_source",
 };
 
-static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu);
+enum cs_etm_version { CS_NOT_PRESENT, CS_ETMV3, CS_ETMV4, CS_ETE };
+
+static bool cs_etm_pmu_file_present(struct auxtrace_record *itr, int cpu,
+				       const char *file);
 static bool cs_etm_is_ete(struct auxtrace_record *itr, int cpu);
 
+static enum cs_etm_version cs_etm_get_version(struct auxtrace_record *itr,
+					      int cpu)
+{
+	if (cs_etm_is_ete(itr, cpu))
+		return CS_ETE;
+	else if (cs_etm_pmu_file_present(itr, cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR0]))
+		return CS_ETMV4;
+	else if (cs_etm_pmu_file_present(itr, cpu, metadata_etmv3_ro[CS_ETM_ETMCCER]))
+		return CS_ETMV3;
+
+	return CS_NOT_PRESENT;
+}
+
 static int cs_etm_validate_context_id(struct auxtrace_record *itr,
 				      struct evsel *evsel, int cpu)
 {
@@ -87,7 +103,7 @@ static int cs_etm_validate_context_id(struct auxtrace_record *itr,
 		return 0;
 
 	/* Not supported in etmv3 */
-	if (!cs_etm_is_etmv4(itr, cpu)) {
+	if (cs_etm_get_version(itr, cpu) == CS_ETMV3) {
 		pr_err("%s: contextid not supported in ETMv3, disable with %s/contextid=0/\n",
 		       CORESIGHT_ETM_PMU_NAME, CORESIGHT_ETM_PMU_NAME);
 		return -EINVAL;
@@ -154,7 +170,7 @@ static int cs_etm_validate_timestamp(struct auxtrace_record *itr,
 	      perf_pmu__format_bits(cs_etm_pmu, "timestamp")))
 		return 0;
 
-	if (!cs_etm_is_etmv4(itr, cpu)) {
+	if (cs_etm_get_version(itr, cpu) == CS_ETMV3) {
 		pr_err("%s: timestamp not supported in ETMv3, disable with %s/timestamp=0/\n",
 		       CORESIGHT_ETM_PMU_NAME, CORESIGHT_ETM_PMU_NAME);
 		return -EINVAL;
@@ -218,6 +234,11 @@ static int cs_etm_validate_config(struct auxtrace_record *itr,
 	}
 
 	perf_cpu_map__for_each_cpu_skip_any(cpu, idx, intersect_cpus) {
+		if (cs_etm_get_version(itr, cpu.cpu) == CS_NOT_PRESENT) {
+			pr_err("%s: Not found on CPU %d. Check hardware and firmware support and that all Coresight drivers are loaded\n",
+			       CORESIGHT_ETM_PMU_NAME, cpu.cpu);
+			return -EINVAL;
+		}
 		err = cs_etm_validate_context_id(itr, evsel, cpu.cpu);
 		if (err)
 			break;
@@ -548,13 +569,13 @@ cs_etm_info_priv_size(struct auxtrace_record *itr __maybe_unused,
 		/* Event can be "any" CPU so count all online CPUs. */
 		intersect_cpus = perf_cpu_map__new_online_cpus();
 	}
+	/* Count number of each type of ETM. Don't count if that CPU has CS_NOT_PRESENT. */
 	perf_cpu_map__for_each_cpu_skip_any(cpu, idx, intersect_cpus) {
-		if (cs_etm_is_ete(itr, cpu.cpu))
-			ete++;
-		else if (cs_etm_is_etmv4(itr, cpu.cpu))
-			etmv4++;
-		else
-			etmv3++;
+		enum cs_etm_version v = cs_etm_get_version(itr, cpu.cpu);
+
+		ete   += v == CS_ETE;
+		etmv4 += v == CS_ETMV4;
+		etmv3 += v == CS_ETMV3;
 	}
 	perf_cpu_map__put(intersect_cpus);
 
@@ -564,7 +585,8 @@ cs_etm_info_priv_size(struct auxtrace_record *itr __maybe_unused,
 	       (etmv3 * CS_ETMV3_PRIV_SIZE));
 }
 
-static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu)
+static bool cs_etm_pmu_file_present(struct auxtrace_record *itr, int cpu,
+				       const char *file)
 {
 	bool ret = false;
 	char path[PATH_MAX];
@@ -574,9 +596,7 @@ static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu)
 			container_of(itr, struct cs_etm_recording, itr);
 	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
 
-	/* Take any of the RO files for ETMv4 and see if it present */
-	snprintf(path, PATH_MAX, "cpu%d/%s",
-		 cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR0]);
+	snprintf(path, PATH_MAX, "cpu%d/%s", cpu, file);
 	scan = perf_pmu__scan_file(cs_etm_pmu, path, "%x", &val);
 
 	/* The file was read successfully, we have a winner */
@@ -735,21 +755,26 @@ static void cs_etm_get_metadata(int cpu, u32 *offset,
 	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
 
 	/* first see what kind of tracer this cpu is affined to */
-	if (cs_etm_is_ete(itr, cpu)) {
+	switch (cs_etm_get_version(itr, cpu)) {
+	case CS_ETE:
 		magic = __perf_cs_ete_magic;
 		cs_etm_save_ete_header(&info->priv[*offset], itr, cpu);
 
 		/* How much space was used */
 		increment = CS_ETE_PRIV_MAX;
 		nr_trc_params = CS_ETE_PRIV_MAX - CS_ETM_COMMON_BLK_MAX_V1;
-	} else if (cs_etm_is_etmv4(itr, cpu)) {
+		break;
+
+	case CS_ETMV4:
 		magic = __perf_cs_etmv4_magic;
 		cs_etm_save_etmv4_header(&info->priv[*offset], itr, cpu);
 
 		/* How much space was used */
 		increment = CS_ETMV4_PRIV_MAX;
 		nr_trc_params = CS_ETMV4_PRIV_MAX - CS_ETMV4_TRCCONFIGR;
-	} else {
+		break;
+
+	case CS_ETMV3:
 		magic = __perf_cs_etmv3_magic;
 		/* Get configuration register */
 		info->priv[*offset + CS_ETM_ETMCR] = cs_etm_get_config(itr);
@@ -767,6 +792,13 @@ static void cs_etm_get_metadata(int cpu, u32 *offset,
 		/* How much space was used */
 		increment = CS_ETM_PRIV_MAX;
 		nr_trc_params = CS_ETM_PRIV_MAX - CS_ETM_ETMCR;
+		break;
+
+	default:
+	case CS_NOT_PRESENT:
+		/* Unreachable, CPUs already validated in cs_etm_validate_config() */
+		assert(true);
+		return;
 	}
 
 	/* Build generic header portion */
-- 
2.34.1