perf probe: Show accessible global variables

Add --externs for allowing --vars to show accessible global (externally
defined) variables from a given probe point too.

This will give you a hint which globals can be accessible from the probe point.

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: <20101021101335.3542.31003.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>
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 83192a5..82b0976 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -379,7 +379,7 @@
 }
 
 static int show_available_vars_at(int fd, struct perf_probe_event *pev,
-				  int max_vls)
+				  int max_vls, bool externs)
 {
 	char *buf;
 	int ret, i;
@@ -391,7 +391,7 @@
 		return -EINVAL;
 	pr_debug("Searching variables at %s\n", buf);
 
-	ret = find_available_vars_at(fd, pev, &vls, max_vls);
+	ret = find_available_vars_at(fd, pev, &vls, max_vls, externs);
 	if (ret > 0) {
 		/* Some variables were found */
 		fprintf(stdout, "Available variables at %s\n", buf);
@@ -421,7 +421,7 @@
 
 /* Show available variables on given probe point */
 int show_available_vars(struct perf_probe_event *pevs, int npevs,
-			int max_vls)
+			int max_vls, bool externs)
 {
 	int i, fd, ret = 0;
 
@@ -438,7 +438,7 @@
 	setup_pager();
 
 	for (i = 0; i < npevs && ret >= 0; i++)
-		ret = show_available_vars_at(fd, &pevs[i], max_vls);
+		ret = show_available_vars_at(fd, &pevs[i], max_vls, externs);
 
 	close(fd);
 	return ret;