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Subject[PATCH 38/85] perf cs-etm: Configure timestamp generation in CPU-wide mode
Date
From: Mathieu Poirier <mathieu.poirier@linaro.org>

When operating in CPU-wide mode tracers need to generate timestamps in
order to correlate the code being traced on one CPU with what is executed
on other CPUs.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Tested-by: Leo Yan <leo.yan@linaro.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190524173508.29044-3-mathieu.poirier@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/arch/arm/util/cs-etm.c | 57 +++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)

diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index 3912f0bf04ed..be1e4f20affa 100644
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -99,6 +99,54 @@ static int cs_etm_set_context_id(struct auxtrace_record *itr,
return err;
}

+static int cs_etm_set_timestamp(struct auxtrace_record *itr,
+ struct perf_evsel *evsel, int cpu)
+{
+ struct cs_etm_recording *ptr;
+ struct perf_pmu *cs_etm_pmu;
+ char path[PATH_MAX];
+ int err = -EINVAL;
+ u32 val;
+
+ ptr = container_of(itr, struct cs_etm_recording, itr);
+ cs_etm_pmu = ptr->cs_etm_pmu;
+
+ if (!cs_etm_is_etmv4(itr, cpu))
+ goto out;
+
+ /* Get a handle on TRCIRD0 */
+ snprintf(path, PATH_MAX, "cpu%d/%s",
+ cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR0]);
+ err = perf_pmu__scan_file(cs_etm_pmu, path, "%x", &val);
+
+ /* There was a problem reading the file, bailing out */
+ if (err != 1) {
+ pr_err("%s: can't read file %s\n",
+ CORESIGHT_ETM_PMU_NAME, path);
+ goto out;
+ }
+
+ /*
+ * TRCIDR0.TSSIZE, bit [28-24], indicates whether global timestamping
+ * is supported:
+ * 0b00000 Global timestamping is not implemented
+ * 0b00110 Implementation supports a maximum timestamp of 48bits.
+ * 0b01000 Implementation supports a maximum timestamp of 64bits.
+ */
+ val &= GENMASK(28, 24);
+ if (!val) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ /* All good, let the kernel know */
+ evsel->attr.config |= (1 << ETM_OPT_TS);
+ err = 0;
+
+out:
+ return err;
+}
+
static int cs_etm_set_option(struct auxtrace_record *itr,
struct perf_evsel *evsel, u32 option)
{
@@ -118,6 +166,11 @@ static int cs_etm_set_option(struct auxtrace_record *itr,
if (err)
goto out;
break;
+ case ETM_OPT_TS:
+ err = cs_etm_set_timestamp(itr, evsel, i);
+ if (err)
+ goto out;
+ break;
default:
goto out;
}
@@ -343,6 +396,10 @@ static int cs_etm_recording_options(struct auxtrace_record *itr,
err = cs_etm_set_option(itr, cs_etm_evsel, ETM_OPT_CTXTID);
if (err)
goto out;
+
+ err = cs_etm_set_option(itr, cs_etm_evsel, ETM_OPT_TS);
+ if (err)
+ goto out;
}

/* Add dummy event to keep tracking */
--
2.20.1
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