perf tools: Support reading PERF_FORMAT_LOST

The recent kernel added lost count can be read from either read(2) or
ring buffer data with PERF_SAMPLE_READ.  As it's a variable length data
we need to access it according to the format info.

But for perf tools use cases, PERF_FORMAT_ID is always set.  So we can
only check PERF_FORMAT_LOST bit to determine the data format.

Add sample_read_value_size() and next_sample_read_value() helpers to
make it a bit easier to access.  Use them in all places where it reads
the struct sample_read_value.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220819003644.508916-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 18 insertions, 11 deletions

diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 4852089e1d79..18c3eb864d55 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1541,7 +1541,7 @@ static int evsel__read_one(struct evsel *evsel, int cpu_map_idx, int thread)
 }
 
 static void evsel__set_count(struct evsel *counter, int cpu_map_idx, int thread,
-			     u64 val, u64 ena, u64 run)
+			     u64 val, u64 ena, u64 run, u64 lost)
 {
 	struct perf_counts_values *count;
 
@@ -1550,6 +1550,7 @@ static void evsel__set_count(struct evsel *counter, int cpu_map_idx, int thread,
 	count->val    = val;
 	count->ena    = ena;
 	count->run    = run;
+	count->lost   = lost;
 
 	perf_counts__set_loaded(counter->counts, cpu_map_idx, thread, true);
 }
@@ -1558,7 +1559,7 @@ static int evsel__process_group_data(struct evsel *leader, int cpu_map_idx, int
 {
 	u64 read_format = leader->core.attr.read_format;
 	struct sample_read_value *v;
-	u64 nr, ena = 0, run = 0, i;
+	u64 nr, ena = 0, run = 0, lost = 0;
 
 	nr = *data++;
 
@@ -1571,18 +1572,18 @@ static int evsel__process_group_data(struct evsel *leader, int cpu_map_idx, int
 	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
 		run = *data++;
 
-	v = (struct sample_read_value *) data;
-
-	evsel__set_count(leader, cpu_map_idx, thread, v[0].value, ena, run);
-
-	for (i = 1; i < nr; i++) {
+	v = (void *)data;
+	sample_read_group__for_each(v, nr, read_format) {
 		struct evsel *counter;
 
-		counter = evlist__id2evsel(leader->evlist, v[i].id);
+		counter = evlist__id2evsel(leader->evlist, v->id);
 		if (!counter)
 			return -EINVAL;
 
-		evsel__set_count(counter, cpu_map_idx, thread, v[i].value, ena, run);
+		if (read_format & PERF_FORMAT_LOST)
+			lost = v->lost;
+
+		evsel__set_count(counter, cpu_map_idx, thread, v->value, ena, run, lost);
 	}
 
 	return 0;
@@ -2475,8 +2476,8 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
 
 			if (data->read.group.nr > max_group_nr)
 				return -EFAULT;
-			sz = data->read.group.nr *
-			     sizeof(struct sample_read_value);
+
+			sz = data->read.group.nr * sample_read_value_size(read_format);
 			OVERFLOW_CHECK(array, sz, max_size);
 			data->read.group.values =
 					(struct sample_read_value *)array;
@@ -2485,6 +2486,12 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
 			OVERFLOW_CHECK_u64(array);
 			data->read.one.id = *array;
 			array++;
+
+			if (read_format & PERF_FORMAT_LOST) {
+				OVERFLOW_CHECK_u64(array);
+				data->read.one.lost = *array;
+				array++;
+			}
 		}
 	}