Fix a wrong "variable not found" warning when the probe point is
not found in the debuginfo.
Since the debuginfo__find_probes() can return 0 even if it does not
find given probe point in the debuginfo, fill_empty_trace_arg() can
be called with tf.ntevs == 0 and it can warn a wrong warning.
To fix this, reject ntevs == 0 in fill_empty_trace_arg().
E.g. without this patch;
# perf probe -x /lib64/libc-2.30.so -a "memcpy arg1=%di"
Failed to find the location of the '%di' variable at this address.
Perhaps it has been optimized out.
Use -V with the --range option to show '%di' location range.
Added new events:
probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di)
probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di)
You can now use it in all perf tools, such as:
perf record -e probe_libc:memcpy -aR sleep 1
With this;
# perf probe -x /lib64/libc-2.30.so -a "memcpy arg1=%di"
Added new events:
probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di)
probe_libc:memcpy (on memcpy in /usr/lib64/libc-2.30.so with arg1=%di)
You can now use it in all perf tools, such as:
perf record -e probe_libc:memcpy -aR sleep 1
Reported-by: Andi Kleen <a...@firstfloor.org>
Fixes: cb4027308570 ("perf probe: Trace a magic number if variable is not
found")
Cc: sta...@vger.kernel.org
Signed-off-by: Masami Hiramatsu <mhira...@kernel.org>
---
tools/perf/util/probe-finder.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 55924255c535..9963e4e8ea20 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1408,6 +1408,9 @@ static int fill_empty_trace_arg(struct perf_probe_event
*pev,
char *type;
int i, j, ret;
+ if (!ntevs)
+ return -ENOENT;
+
for (i = 0; i < pev->nargs; i++) {
type = NULL;
for (j = 0; j < ntevs; j++) {
