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@devboxSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/Documentation/perf-probe.txt

@@ -21,6 +21,8 @@ or
 'perf probe' [options] --vars='PROBEPOINT'
 or
 'perf probe' [options] --funcs
+or
+'perf probe' [options] --definition='PROBE' [...]
 
 DESCRIPTION
 -----------
@@ -96,6 +98,11 @@ OPTIONS
 	can also list functions in a user space executable / shared library.
 	This also can accept a FILTER rule argument.
 
+-D::
+--definition=::
+	Show trace-event definition converted from given probe-event instead
+	of write it into tracing/[k,u]probe_events.
+
 --filter=FILTER::
 	(Only for --vars and --funcs) Set filter. FILTER is a combination of glob
 	pattern, see FILTER PATTERN for detail.

tools/perf/builtin-probe.c

@@ -326,6 +326,11 @@ static int perf_add_probe_events(struct perf_probe_event *pevs, int npevs)
 	if (ret < 0)
 		goto out_cleanup;
 
+	if (params.command == 'D') {	/* it shows definition */
+		ret = show_probe_trace_events(pevs, npevs);
+		goto out_cleanup;
+	}
+
 	ret = apply_perf_probe_events(pevs, npevs);
 	if (ret < 0)
 		goto out_cleanup;
@@ -454,6 +459,14 @@ static int perf_del_probe_events(struct strfilter *filter)
 	return ret;
 }
 
+#ifdef HAVE_DWARF_SUPPORT
+#define PROBEDEF_STR	\
+	"[EVENT=]FUNC[@SRC][+OFF|%return|:RL|;PT]|SRC:AL|SRC;PT [[NAME=]ARG ...]"
+#else
+#define PROBEDEF_STR	"[EVENT=]FUNC[+OFF|%return] [[NAME=]ARG ...]"
+#endif
+
+
 static int
 __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 {
@@ -479,13 +492,7 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 			     opt_set_filter_with_command, DEFAULT_LIST_FILTER),
 	OPT_CALLBACK('d', "del", NULL, "[GROUP:]EVENT", "delete a probe event.",
 		     opt_set_filter_with_command),
-	OPT_CALLBACK('a', "add", NULL,
-#ifdef HAVE_DWARF_SUPPORT
-		"[EVENT=]FUNC[@SRC][+OFF|%return|:RL|;PT]|SRC:AL|SRC;PT"
-		" [[NAME=]ARG ...]",
-#else
-		"[EVENT=]FUNC[+OFF|%return] [[NAME=]ARG ...]",
-#endif
+	OPT_CALLBACK('a', "add", NULL, PROBEDEF_STR,
 		"probe point definition, where\n"
 		"\t\tGROUP:\tGroup name (optional)\n"
 		"\t\tEVENT:\tEvent name\n"
@@ -503,6 +510,9 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 		"\t\tARG:\tProbe argument (kprobe-tracer argument format.)\n",
 #endif
 		opt_add_probe_event),
+	OPT_CALLBACK('D', "definition", NULL, PROBEDEF_STR,
+		"Show trace event definition of given traceevent for k/uprobe_events.",
+		opt_add_probe_event),
 	OPT_BOOLEAN('f', "force", &probe_conf.force_add, "forcibly add events"
 		    " with existing name"),
 	OPT_CALLBACK('L', "line", NULL,
@@ -548,6 +558,7 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 
 	set_option_flag(options, 'a', "add", PARSE_OPT_EXCLUSIVE);
 	set_option_flag(options, 'd', "del", PARSE_OPT_EXCLUSIVE);
+	set_option_flag(options, 'D', "definition", PARSE_OPT_EXCLUSIVE);
 	set_option_flag(options, 'l', "list", PARSE_OPT_EXCLUSIVE);
 #ifdef HAVE_DWARF_SUPPORT
 	set_option_flag(options, 'L', "line", PARSE_OPT_EXCLUSIVE);
@@ -644,6 +655,7 @@ __cmd_probe(int argc, const char **argv, const char *prefix __maybe_unused)
 		}
 		break;
 	case 'a':
+	case 'D':
 		/* Ensure the last given target is used */
 		if (params.target && !params.target_used) {
 			pr_err("  Error: -x/-m must follow the probe definitions.\n");

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;

tools/perf/util/probe-event.h

@@ -147,6 +147,7 @@ int line_range__init(struct line_range *lr);
 int add_perf_probe_events(struct perf_probe_event *pevs, int npevs);
 int convert_perf_probe_events(struct perf_probe_event *pevs, int npevs);
 int apply_perf_probe_events(struct perf_probe_event *pevs, int npevs);
+int show_probe_trace_events(struct perf_probe_event *pevs, int npevs);
 void cleanup_perf_probe_events(struct perf_probe_event *pevs, int npevs);
 int del_perf_probe_events(struct strfilter *filter);