[tip:perf/core] perf script python: Use PyBytes for attr in trace-event-python

[tip-bot for Tony Jones]

Commit-ID:  72e0b15cb24a497d7d0d4707cf51ff40c185ae8c
Gitweb:     https://git.kernel.org/tip/72e0b15cb24a497d7d0d4707cf51ff40c185ae8c
Author:     Tony Jones <to...@suse.de>
AuthorDate: Wed, 23 Jan 2019 16:52:25 -0800
Committer:  Arnaldo Carvalho de Melo <a...@redhat.com>
CommitDate: Fri, 25 Jan 2019 15:12:10 +0100

perf script python: Use PyBytes for attr in trace-event-python

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 <to...@suse.de>
Acked-by: Jiri Olsa <jo...@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <a...@redhat.com>
Cc: Jaroslav Škarvada <jskar...@redhat.com>
Cc: Jonathan Corbet <cor...@lwn.net>
Cc: Ravi Bangoria <ravi.bango...@linux.ibm.com>
Cc: Seeteena Thoufeek <s1see...@linux.vnet.ibm.com>
Fixes: 66dfdff03d19 ("perf tools: Add Python 3 support")
Link: http://lkml.kernel.org/r/20190124005229.16146-3-to...@suse.de
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
---
 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 315905c748fa..7059d1be2d09 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));