[tip:perf/core] perf arm cs-etm: Use event attributes to send sink information to kernel

[tip-bot for Mathieu Poirier]

Commit-ID:  fa4e819bbca9939c54e87ba994a6a9bffd0247df
Gitweb:     https://git.kernel.org/tip/fa4e819bbca9939c54e87ba994a6a9bffd0247df
Author:     Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
AuthorDate: Thu, 31 Jan 2019 11:47:12 -0700
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Wed, 6 Feb 2019 10:00:39 -0300

perf arm cs-etm: Use event attributes to send sink information to kernel

The communication of sink information for a trace session doesn't work
when more than on CPU is involved in the scenario due to the static
nature of sysfs.  As such communicate the sink information to each event
by using the perf_event::attr:config2 attribute.  The information sent
to the kernel is an hash of the sink's name, which is unique in a
system.

Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Acked-by: Suzuki K Poulouse <suzuki.poulose@xxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-s390@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20190131184714.20388-6-mathieu.poirier@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/arch/arm/util/cs-etm.c | 44 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index 2f595cd73da6..4f31cf0d1e6d 100644
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -5,6 +5,7 @@
  */
 
 #include <api/fs/fs.h>
+#include <linux/bits.h>
 #include <linux/bitops.h>
 #include <linux/compiler.h>
 #include <linux/coresight-pmu.h>
@@ -22,6 +23,7 @@
 #include "../../util/thread_map.h"
 #include "../../util/cs-etm.h"
 
+#include <errno.h>
 #include <stdlib.h>
 #include <sys/stat.h>
 
@@ -60,10 +62,48 @@ static int cs_etm_parse_snapshot_options(struct auxtrace_record *itr,
 	return 0;
 }
 
+static int cs_etm_set_sink_attr(struct perf_pmu *pmu,
+				struct perf_evsel *evsel)
+{
+	char msg[BUFSIZ], path[PATH_MAX], *sink;
+	struct perf_evsel_config_term *term;
+	int ret = -EINVAL;
+	u32 hash;
+
+	if (evsel->attr.config2 & GENMASK(31, 0))
+		return 0;
+
+	list_for_each_entry(term, &evsel->config_terms, list) {
+		if (term->type != PERF_EVSEL__CONFIG_TERM_DRV_CFG)
+			continue;
+
+		sink = term->val.drv_cfg;
+		snprintf(path, PATH_MAX, "sinks/%s", sink);
+
+		ret = perf_pmu__scan_file(pmu, path, "%x", &hash);
+		if (ret != 1) {
+			pr_err("failed to set sink \"%s\" on event %s with %d (%s)\n",
+			       sink, perf_evsel__name(evsel), errno,
+			       str_error_r(errno, msg, sizeof(msg)));
+			return ret;
+		}
+
+		evsel->attr.config2 |= hash;
+		return 0;
+	}
+
+	/*
+	 * No sink was provided on the command line - for _now_ treat
+	 * this as an error.
+	 */
+	return ret;
+}
+
 static int cs_etm_recording_options(struct auxtrace_record *itr,
 				    struct perf_evlist *evlist,
 				    struct record_opts *opts)
 {
+	int ret;
 	struct cs_etm_recording *ptr =
 				container_of(itr, struct cs_etm_recording, itr);
 	struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
@@ -92,6 +132,10 @@ static int cs_etm_recording_options(struct auxtrace_record *itr,
 	if (!cs_etm_evsel)
 		return 0;
 
+	ret = cs_etm_set_sink_attr(cs_etm_pmu, cs_etm_evsel);
+	if (ret)
+		return ret;
+
 	if (opts->use_clockid) {
 		pr_err("Cannot use clockid (-k option) with %s\n",
 		       CORESIGHT_ETM_PMU_NAME);