[PATCH AUTOSEL 4.19 06/65] perf script: Fix crash with printing mixed trace point and other events

Sasha Levin
2019-02-23T21:28:18Z

From: Andi Kleen <ak@linux.intel.com>

[ Upstream commit 96167167b6e17b25c0e05ecc31119b73baeab094 ]

'perf script' crashes currently when printing mixed trace points and
other events because the trace format does not handle events without
trace meta data. Add a simple check to avoid that.

% cat > test.c
main()
{
printf("Hello world\n");
}
^D
% gcc -g -o test test.c
% sudo perf probe -x test 'test.c:3'
% perf record -e '{cpu/cpu-cycles,period=10000/,probe_test:main}:S' ./test
% perf script
<segfault>

Committer testing:

Before:

# perf probe -x /lib64/libc-2.28.so malloc
Added new event:
probe_libc:malloc (on malloc in /usr/lib64/libc-2.28.so)

You can now use it in all perf tools, such as:

perf record -e probe_libc:malloc -aR sleep 1

# perf probe -l
probe_libc:malloc (on __libc_malloc@malloc/malloc.c in /usr/lib64/libc-2.28.so)
# perf record -e '{cpu/cpu-cycles,period=10000/,probe_libc:*}:S' sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.023 MB perf.data (40 samples) ]
# perf script
Segmentation fault (core dumped)
^C
#

After:

# perf script | head -6
sleep 2888 94796.944981: 16198 cpu/cpu-cycles,period=10000/: ffffffff925dc04f get_random_u32+0x1f (/lib/modules/5.0.0-rc2+/build/vmlinux)
sleep 2888 [-01] 94796.944981: probe_libc:malloc:
sleep 2888 94796.944983: 4713 cpu/cpu-cycles,period=10000/: ffffffff922763af change_protection+0xcf (/lib/modules/5.0.0-rc2+/build/vmlinux)
sleep 2888 [-01] 94796.944983: probe_libc:malloc:
sleep 2888 94796.944986: 9934 cpu/cpu-cycles,period=10000/: ffffffff922777e0 move_page_tables+0x0 (/lib/modules/5.0.0-rc2+/build/vmlinux)
sleep 2888 [-01] 94796.944986: probe_libc:malloc:
#

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20190117194834.21940-1-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/builtin-script.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 6c1e7ceedcf30..ce2aee11e3605 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -1658,7 +1658,7 @@ static void process_event(struct perf_script *script,
return;
}

- if (PRINT_FIELD(TRACE)) {
+ if (PRINT_FIELD(TRACE) && sample->raw_data) {
event_format__fprintf(evsel->tp_format, sample->cpu,
sample->raw_data, sample->raw_size, fp);
}
--
2.19.1