perf probe: Show accessible local variables

Add -V (--vars) option for listing accessible local variables at given probe
point. This will help finding which local variables are available for event
arguments.

e.g.)
 # perf probe -V call_timer_fn:23
 Available variables at call_timer_fn:23
         @<run_timer_softirq+345>
                 function_type*  fn
                 int     preempt_count
                 long unsigned int       data
                 struct list_head        work_list
                 struct list_head*       head
                 struct timer_list*      timer
                 struct tvec_base*       base

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20101021101323.3542.40282.stgit@ltc236.sdl.hitachi.co.jp>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 54 insertions, 7 deletions

diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index 199d5e19554..91bb6cf4e02 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -50,6 +50,8 @@ static struct {
 	bool list_events;
 	bool force_add;
 	bool show_lines;
+	bool show_vars;
+	bool mod_events;
 	int nevents;
 	struct perf_probe_event events[MAX_PROBES];
 	struct strlist *dellist;
@@ -57,7 +59,6 @@ static struct {
 	int max_probe_points;
 } params;
 
-
 /* Parse an event definition. Note that any error must die. */
 static int parse_probe_event(const char *str)
 {
@@ -92,6 +93,7 @@ static int parse_probe_event_argv(int argc, const char **argv)
 	len = 0;
 	for (i = 0; i < argc; i++)
 		len += sprintf(&buf[len], "%s ", argv[i]);
+	params.mod_events = true;
 	ret = parse_probe_event(buf);
 	free(buf);
 	return ret;
@@ -100,9 +102,10 @@ static int parse_probe_event_argv(int argc, const char **argv)
 static int opt_add_probe_event(const struct option *opt __used,
 			      const char *str, int unset __used)
 {
-	if (str)
+	if (str) {
+		params.mod_events = true;
 		return parse_probe_event(str);
-	else
+	} else
 		return 0;
 }
 
@@ -110,6 +113,7 @@ static int opt_del_probe_event(const struct option *opt __used,
 			       const char *str, int unset __used)
 {
 	if (str) {
+		params.mod_events = true;
 		if (!params.dellist)
 			params.dellist = strlist__new(true, NULL);
 		strlist__add(params.dellist, str);
@@ -130,6 +134,25 @@ static int opt_show_lines(const struct option *opt __used,
 
 	return ret;
 }
+
+static int opt_show_vars(const struct option *opt __used,
+			 const char *str, int unset __used)
+{
+	struct perf_probe_event *pev = &params.events[params.nevents];
+	int ret;
+
+	if (!str)
+		return 0;
+
+	ret = parse_probe_event(str);
+	if (!ret && pev->nargs != 0) {
+		pr_err("  Error: '--vars' doesn't accept arguments.\n");
+		return -EINVAL;
+	}
+	params.show_vars = true;
+
+	return ret;
+}
 #endif
 
 static const char * const probe_usage[] = {
@@ -139,6 +162,7 @@ static const char * const probe_usage[] = {
 	"perf probe --list",
 #ifdef DWARF_SUPPORT
 	"perf probe --line 'LINEDESC'",
+	"perf probe --vars 'PROBEPOINT'",
 #endif
 	NULL
 };
@@ -180,6 +204,9 @@ static const struct option options[] = {
 	OPT_CALLBACK('L', "line", NULL,
 		     "FUNC[:RLN[+NUM|-RLN2]]|SRC:ALN[+NUM|-ALN2]",
 		     "Show source code lines.", opt_show_lines),
+	OPT_CALLBACK('V', "vars", NULL,
+		     "FUNC[@SRC][+OFF|%return|:RL|;PT]|SRC:AL|SRC;PT",
+		     "Show accessible variables on PROBEDEF", opt_show_vars),
 	OPT_STRING('k', "vmlinux", &symbol_conf.vmlinux_name,
 		   "file", "vmlinux pathname"),
 	OPT_STRING('s', "source", &symbol_conf.source_prefix,
@@ -217,7 +244,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 		usage_with_options(probe_usage, options);
 
 	if (params.list_events) {
-		if (params.nevents != 0 || params.dellist) {
+		if (params.mod_events) {
 			pr_err("  Error: Don't use --list with --add/--del.\n");
 			usage_with_options(probe_usage, options);
 		}
@@ -225,6 +252,10 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 			pr_err("  Error: Don't use --list with --line.\n");
 			usage_with_options(probe_usage, options);
 		}
+		if (params.show_vars) {
+			pr_err(" Error: Don't use --list with --vars.\n");
+			usage_with_options(probe_usage, options);
+		}
 		ret = show_perf_probe_events();
 		if (ret < 0)
 			pr_err("  Error: Failed to show event list. (%d)\n",
@@ -234,9 +265,13 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 
 #ifdef DWARF_SUPPORT
 	if (params.show_lines) {
-		if (params.nevents != 0 || params.dellist) {
-			pr_warning("  Error: Don't use --line with"
-				   " --add/--del.\n");
+		if (params.mod_events) {
+			pr_err("  Error: Don't use --line with"
+			       " --add/--del.\n");
+			usage_with_options(probe_usage, options);
+		}
+		if (params.show_vars) {
+			pr_err(" Error: Don't use --line with --vars.\n");
 			usage_with_options(probe_usage, options);
 		}
 
@@ -245,6 +280,18 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 			pr_err("  Error: Failed to show lines. (%d)\n", ret);
 		return ret;
 	}
+	if (params.show_vars) {
+		if (params.mod_events) {
+			pr_err("  Error: Don't use --vars with"
+			       " --add/--del.\n");
+			usage_with_options(probe_usage, options);
+		}
+		ret = show_available_vars(params.events, params.nevents,
+					  params.max_probe_points);
+		if (ret < 0)
+			pr_err("  Error: Failed to show vars. (%d)\n", ret);
+		return ret;
+	}
 #endif
 
 	if (params.dellist) {