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>
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index fcc16e4..288ebe8 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -378,6 +378,72 @@
return ret;
}
+static int show_available_vars_at(int fd, struct perf_probe_event *pev,
+ int max_vls)
+{
+ char *buf;
+ int ret, i;
+ struct str_node *node;
+ struct variable_list *vls = NULL, *vl;
+
+ buf = synthesize_perf_probe_point(&pev->point);
+ if (!buf)
+ return -EINVAL;
+ pr_debug("Searching variables at %s\n", buf);
+
+ ret = find_available_vars_at(fd, pev, &vls, max_vls);
+ if (ret > 0) {
+ /* Some variables were found */
+ fprintf(stdout, "Available variables at %s\n", buf);
+ for (i = 0; i < ret; i++) {
+ vl = &vls[i];
+ /*
+ * A probe point might be converted to
+ * several trace points.
+ */
+ fprintf(stdout, "\t@<%s+%lu>\n", vl->point.symbol,
+ vl->point.offset);
+ free(vl->point.symbol);
+ if (vl->vars) {
+ strlist__for_each(node, vl->vars)
+ fprintf(stdout, "\t\t%s\n", node->s);
+ strlist__delete(vl->vars);
+ } else
+ fprintf(stdout, "(No variables)\n");
+ }
+ free(vls);
+ } else
+ pr_err("Failed to find variables at %s (%d)\n", buf, ret);
+
+ free(buf);
+ return ret;
+}
+
+/* Show available variables on given probe point */
+int show_available_vars(struct perf_probe_event *pevs, int npevs,
+ int max_vls)
+{
+ int i, fd, ret = 0;
+
+ ret = init_vmlinux();
+ if (ret < 0)
+ return ret;
+
+ fd = open_vmlinux();
+ if (fd < 0) {
+ pr_warning("Failed to open debuginfo file.\n");
+ return fd;
+ }
+
+ setup_pager();
+
+ for (i = 0; i < npevs && ret >= 0; i++)
+ ret = show_available_vars_at(fd, &pevs[i], max_vls);
+
+ close(fd);
+ return ret;
+}
+
#else /* !DWARF_SUPPORT */
static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
@@ -409,6 +475,12 @@
return -ENOSYS;
}
+int show_available_vars(struct perf_probe_event *pevs __unused,
+ int npevs __unused, int max_probe_points __unused)
+{
+ pr_warning("Debuginfo-analysis is not supported.\n");
+ return -ENOSYS;
+}
#endif
int parse_line_range_desc(const char *arg, struct line_range *lr)