perf probe: Add --bootconfig to output definition in bootconfig format

Now the boot-time tracing supports kprobes events and that must be
written in bootconfig file in the following format.

  ftrace.event.kprobes.<EVENT_NAME>.probes = <PROBE-DEF>

'perf probe' already supports --definition (-D) action to show probe
definitions, but the format is for tracefs:

  [p|r][:EVENT_NAME] <PROBE-DEF>

This patch adds the --bootconfig option for -D action so that it outputs
the probe definitions in bootconfig format. E.g.

  $ perf probe --bootconfig -D "path_lookupat:7 err:s32 s:string"
  ftrace.event.kprobes.path_lookupat_L7.probe = 'path_lookupat.isra.0+309 err_s32=%ax:s32 s_string=+0(%r13):string'

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/162282412351.452340.14871995440005640114.stgit@devnote2
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-probe.c

@@ -347,7 +347,10 @@ static int perf_add_probe_events(struct perf_probe_event *pevs, int npevs)
 		goto out_cleanup;
 
 	if (params.command == 'D') {	/* it shows definition */
-		ret = show_probe_trace_events(pevs, npevs);
+		if (probe_conf.bootconfig)
+			ret = show_bootconfig_events(pevs, npevs);
+		else
+			ret = show_probe_trace_events(pevs, npevs);
 		goto out_cleanup;
 	}
 
@@ -581,6 +584,8 @@ __cmd_probe(int argc, const char **argv)
 		   "Look for files with symbols relative to this directory"),
 	OPT_CALLBACK(0, "target-ns", NULL, "pid",
 		     "target pid for namespace contexts", opt_set_target_ns),
+	OPT_BOOLEAN(0, "bootconfig", &probe_conf.bootconfig,
+		    "Output probe definition with bootconfig format"),
 	OPT_END()
 	};
 	int ret;
@@ -692,6 +697,11 @@ __cmd_probe(int argc, const char **argv)
 		}
 		break;
 	case 'D':
+		if (probe_conf.bootconfig && params.uprobes) {
+			pr_err("  Error: --bootconfig doesn't support uprobes.\n");
+			return -EINVAL;
+		}
+		__fallthrough;
 	case 'a':
 
 		/* Ensure the last given target is used */

tools/perf/util/probe-event.c

@@ -3564,6 +3564,78 @@ int show_probe_trace_events(struct perf_probe_event *pevs, int npevs)
 	return ret;
 }
 
+static int show_bootconfig_event(struct probe_trace_event *tev)
+{
+	struct probe_trace_point *tp = &tev->point;
+	struct strbuf buf;
+	char *ret = NULL;
+	int err;
+
+	if (strbuf_init(&buf, 32) < 0)
+		return -ENOMEM;
+
+	err = synthesize_kprobe_trace_def(tp, &buf);
+	if (err >= 0)
+		err = synthesize_probe_trace_args(tev, &buf);
+	if (err >= 0)
+		ret = strbuf_detach(&buf, NULL);
+	strbuf_release(&buf);
+
+	if (ret) {
+		printf("'%s'", ret);
+		free(ret);
+	}
+
+	return err;
+}
+
+int show_bootconfig_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;
+	char *cur_name = NULL;
+	int i, j, ret = 0;
+
+	if (!namelist)
+		return -ENOMEM;
+
+	for (j = 0; j < npevs && !ret; j++) {
+		pev = &pevs[j];
+		if (pev->group && strcmp(pev->group, "probe"))
+			pr_warning("WARN: Group name %s is ignored\n", pev->group);
+		if (pev->uprobes) {
+			pr_warning("ERROR: Bootconfig doesn't support uprobes\n");
+			ret = -EINVAL;
+			break;
+		}
+		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)
+				break;
+
+			if (!cur_name || strcmp(cur_name, tev->event)) {
+				printf("%sftrace.event.kprobes.%s.probe = ",
+					cur_name ? "\n" : "", tev->event);
+				cur_name = tev->event;
+			} else
+				printf(", ");
+			ret = show_bootconfig_event(tev);
+		}
+	}
+	printf("\n");
+	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

@@ -15,6 +15,7 @@ struct probe_conf {
 	bool	force_add;
 	bool	no_inlines;
 	bool	cache;
+	bool	bootconfig;
 	int	max_probes;
 	unsigned long	magic_num;
 };
@@ -163,6 +164,7 @@ 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);
+int show_bootconfig_events(struct perf_probe_event *pevs, int npevs);
 void cleanup_perf_probe_events(struct perf_probe_event *pevs, int npevs);
 
 struct strfilter;