perf auxtrace: Add support for AUX area sample recording

Add support for parsing and validating AUX area sample options. At
present, the only option is the sample size, but it is also necessary to
ensure that events are in a group with an AUX area event as the leader.

Committer note:

Add missing 'static inline' in front of auxtrace_parse_sample_options()
for when we don't HAVE_AUXTRACE_SUPPORT.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20191115124225.5247-6-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 107 insertions, 0 deletions

diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index 263d1d9d8987..51fbe01f8a11 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -69,6 +69,13 @@ static struct perf_pmu *perf_evsel__find_pmu(struct evsel *evsel)
 	return pmu;
 }
 
+static bool perf_evsel__is_aux_event(struct evsel *evsel)
+{
+	struct perf_pmu *pmu = perf_evsel__find_pmu(evsel);
+
+	return pmu && pmu->auxtrace;
+}
+
 static bool auxtrace__dont_decode(struct perf_session *session)
 {
 	return !session->itrace_synth_opts ||
@@ -609,6 +616,106 @@ int auxtrace_parse_snapshot_options(struct auxtrace_record *itr,
 	return -EINVAL;
 }
 
+/*
+ * Event record size is 16-bit which results in a maximum size of about 64KiB.
+ * Allow about 4KiB for the rest of the sample record, to give a maximum
+ * AUX area sample size of 60KiB.
+ */
+#define MAX_AUX_SAMPLE_SIZE (60 * 1024)
+
+/* Arbitrary default size if no other default provided */
+#define DEFAULT_AUX_SAMPLE_SIZE (4 * 1024)
+
+static int auxtrace_validate_aux_sample_size(struct evlist *evlist,
+					     struct record_opts *opts)
+{
+	struct evsel *evsel;
+	bool has_aux_leader = false;
+	u32 sz;
+
+	evlist__for_each_entry(evlist, evsel) {
+		sz = evsel->core.attr.aux_sample_size;
+		if (perf_evsel__is_group_leader(evsel)) {
+			has_aux_leader = perf_evsel__is_aux_event(evsel);
+			if (sz) {
+				if (has_aux_leader)
+					pr_err("Cannot add AUX area sampling to an AUX area event\n");
+				else
+					pr_err("Cannot add AUX area sampling to a group leader\n");
+				return -EINVAL;
+			}
+		}
+		if (sz > MAX_AUX_SAMPLE_SIZE) {
+			pr_err("AUX area sample size %u too big, max. %d\n",
+			       sz, MAX_AUX_SAMPLE_SIZE);
+			return -EINVAL;
+		}
+		if (sz) {
+			if (!has_aux_leader) {
+				pr_err("Cannot add AUX area sampling because group leader is not an AUX area event\n");
+				return -EINVAL;
+			}
+			perf_evsel__set_sample_bit(evsel, AUX);
+			opts->auxtrace_sample_mode = true;
+		} else {
+			perf_evsel__reset_sample_bit(evsel, AUX);
+		}
+	}
+
+	if (!opts->auxtrace_sample_mode) {
+		pr_err("AUX area sampling requires an AUX area event group leader plus other events to which to add samples\n");
+		return -EINVAL;
+	}
+
+	if (!perf_can_aux_sample()) {
+		pr_err("AUX area sampling is not supported by kernel\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int auxtrace_parse_sample_options(struct auxtrace_record *itr,
+				  struct evlist *evlist,
+				  struct record_opts *opts, const char *str)
+{
+	bool has_aux_leader = false;
+	struct evsel *evsel;
+	char *endptr;
+	unsigned long sz;
+
+	if (!str)
+		return 0;
+
+	if (!itr) {
+		pr_err("No AUX area event to sample\n");
+		return -EINVAL;
+	}
+
+	sz = strtoul(str, &endptr, 0);
+	if (*endptr || sz > UINT_MAX) {
+		pr_err("Bad AUX area sampling option: '%s'\n", str);
+		return -EINVAL;
+	}
+
+	if (!sz)
+		sz = itr->default_aux_sample_size;
+
+	if (!sz)
+		sz = DEFAULT_AUX_SAMPLE_SIZE;
+
+	/* Set aux_sample_size based on --aux-sample option */
+	evlist__for_each_entry(evlist, evsel) {
+		if (perf_evsel__is_group_leader(evsel)) {
+			has_aux_leader = perf_evsel__is_aux_event(evsel);
+		} else if (has_aux_leader) {
+			evsel->core.attr.aux_sample_size = sz;
+		}
+	}
+
+	return auxtrace_validate_aux_sample_size(evlist, opts);
+}
+
 struct auxtrace_record *__weak
 auxtrace_record__init(struct evlist *evlist __maybe_unused, int *err)
 {