[PATCH AUTOSEL 5.0 213/262] perf script python: Use PyBytes for attr in trace-event-python

Sasha Levin
2019-03-27T18:09:04Z

From: Tony Jones <tonyj@suse.de>

[ Upstream commit 72e0b15cb24a497d7d0d4707cf51ff40c185ae8c ]

With Python3. PyUnicode_FromStringAndSize is unsafe to call on attr and will
return NULL. Use _PyBytes_FromStringAndSize (as with raw_buf).

Below is the observed behavior without the fix. Note it is first necessary
to apply the prior fix (Add trace_context extension module to sys,modules):

# ldd /usr/bin/perf | grep -i python
libpython3.6m.so.1.0 => /usr/lib64/libpython3.6m.so.1.0 (0x00007f8e1dfb2000)

# perf record -e raw_syscalls:sys_enter /bin/false
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.018 MB perf.data (21 samples) ]

# perf script -g python | cat
generated Python script: perf-script.py

# perf script -s ./perf-script.py
in trace_begin
Segmentation fault (core dumped)

Signed-off-by: Tony Jones <tonyj@suse.de>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jaroslav Škarvada <jskarvad@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Seeteena Thoufeek <s1seetee@linux.vnet.ibm.com>
Fixes: 66dfdff03d19 ("perf tools: Add Python 3 support")
Link: http://lkml.kernel.org/r/20190124005229.16146-3-tonyj@suse.de
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/perf/util/scripting-engines/trace-event-python.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index 87ef16a1b17e..2fe3cc43526f 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -733,8 +733,7 @@ static PyObject *get_perf_sample_dict(struct perf_sample *sample,
Py_FatalError("couldn't create Python dictionary");

pydict_set_item_string_decref(dict, "ev_name", _PyUnicode_FromString(perf_evsel__name(evsel)));
- pydict_set_item_string_decref(dict, "attr", _PyUnicode_FromStringAndSize(
- (const char *)&evsel->attr, sizeof(evsel->attr)));
+ pydict_set_item_string_decref(dict, "attr", _PyBytes_FromStringAndSize((const char *)&evsel->attr, sizeof(evsel->attr)));

pydict_set_item_string_decref(dict_sample, "pid",
_PyLong_FromLong(sample->pid));
--
2.19.1