Messages in this thread Patch in this message |  | | From | Masami Hiramatsu <> | Subject | [PATCH 2/4] perf-probe: Fix wrong variable warning when the probe point is not found | Date | Thu, 9 Jul 2020 17:07:12 +0900 |
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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 <andi@firstfloor.org> Fixes: cb4027308570 ("perf probe: Trace a magic number if variable is not found") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu <mhiramat@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++) {
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