libperf: Adopt perf_evsel__read() function from tools/perf

Move the perf_evsel__read() function to libperf as a public interface
together with struct perf_counts_values for returning counter values.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190721112506.12306-65-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/tools/perf/lib/evsel.c b/tools/perf/lib/evsel.c
index 50f09e939229..390fcf9107c1 100644
--- a/tools/perf/lib/evsel.c
+++ b/tools/perf/lib/evsel.c
@@ -12,6 +12,7 @@
 #include <internal/xyarray.h>
 #include <internal/cpumap.h>
 #include <internal/threadmap.h>
+#include <internal/lib.h>
 #include <linux/string.h>
 
 void perf_evsel__init(struct perf_evsel *evsel, struct perf_event_attr *attr)
@@ -137,3 +138,44 @@ void perf_evsel__close(struct perf_evsel *evsel)
 	perf_evsel__close_fd(evsel);
 	perf_evsel__free_fd(evsel);
 }
+
+int perf_evsel__read_size(struct perf_evsel *evsel)
+{
+	u64 read_format = evsel->attr.read_format;
+	int entry = sizeof(u64); /* value */
+	int size = 0;
+	int nr = 1;
+
+	if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+		size += sizeof(u64);
+
+	if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+		size += sizeof(u64);
+
+	if (read_format & PERF_FORMAT_ID)
+		entry += sizeof(u64);
+
+	if (read_format & PERF_FORMAT_GROUP) {
+		nr = evsel->nr_members;
+		size += sizeof(u64);
+	}
+
+	size += entry * nr;
+	return size;
+}
+
+int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread,
+		     struct perf_counts_values *count)
+{
+	size_t size = perf_evsel__read_size(evsel);
+
+	memset(count, 0, sizeof(*count));
+
+	if (FD(evsel, cpu, thread) < 0)
+		return -EINVAL;
+
+	if (readn(FD(evsel, cpu, thread), count->values, size) <= 0)
+		return -errno;
+
+	return 0;
+}