perf probe: Show trace event definition

Add --definition/-D option for showing the trace-event definition in
stdout. This can be useful in debugging or combined with a shell script.

e.g.
  ----
  # perf probe --definition 'do_sys_open $params'
  p:probe/do_sys_open _text+2261728 dfd=%di:s32 filename=%si:u64 flags=%dx:s32 mode=%cx:u16
  ----

Suggested-and-Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/147214226712.23638.2240534040014013658.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 46 insertions, 0 deletions

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 0bed2ee..4a49cb8 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -3207,6 +3207,52 @@ int convert_perf_probe_events(struct perf_probe_event *pevs, int npevs)
 	return 0;
 }
 
+static int show_probe_trace_event(struct probe_trace_event *tev)
+{
+	char *buf = synthesize_probe_trace_command(tev);
+
+	if (!buf) {
+		pr_debug("Failed to synthesize probe trace event.\n");
+		return -EINVAL;
+	}
+
+	/* Showing definition always go stdout */
+	printf("%s\n", buf);
+	free(buf);
+
+	return 0;
+}
+
+int show_probe_trace_events(struct perf_probe_event *pevs, int npevs)
+{
+	struct strlist *namelist = strlist__new(NULL, NULL);
+	struct probe_trace_event *tev;
+	struct perf_probe_event *pev;
+	int i, j, ret = 0;
+
+	if (!namelist)
+		return -ENOMEM;
+
+	for (j = 0; j < npevs && !ret; j++) {
+		pev = &pevs[j];
+		for (i = 0; i < pev->ntevs && !ret; i++) {
+			tev = &pev->tevs[i];
+			/* Skip if the symbol is out of .text or blacklisted */
+			if (!tev->point.symbol && !pev->uprobes)
+				continue;
+
+			/* Set new name for tev (and update namelist) */
+			ret = probe_trace_event__set_name(tev, pev,
+							  namelist, true);
+			if (!ret)
+				ret = show_probe_trace_event(tev);
+		}
+	}
+	strlist__delete(namelist);
+
+	return ret;
+}
+
 int apply_perf_probe_events(struct perf_probe_event *pevs, int npevs)
 {
 	int i, ret = 0;