linux-stable.git/tools/perf/util/python.c, branch v6.15

perf python: Check if there is space to copy all the event

2025-03-18T23:08:45+00:00

The pyrf_event__new() method copies the event obtained from the perf
ring buffer to a structure that will then be turned into a python object
for further consumption, so it copies perf_event.header.size bytes to
its 'event' member:

  $ pahole -C pyrf_event /tmp/build/perf-tools-next/python/perf.cpython-312-x86_64-linux-gnu.so
  struct pyrf_event {
  	PyObject                   ob_base;              /*     0    16 */
  	struct evsel *             evsel;                /*    16     8 */
  	struct perf_sample         sample;               /*    24   312 */

  	/* XXX last struct has 7 bytes of padding, 2 holes */

  	/* --- cacheline 5 boundary (320 bytes) was 16 bytes ago --- */
  	union perf_event           event;                /*   336  4168 */

  	/* size: 4504, cachelines: 71, members: 4 */
  	/* member types with holes: 1, total: 2 */
  	/* paddings: 1, sum paddings: 7 */
  	/* last cacheline: 24 bytes */
  };

  $

It was doing so without checking if the event just obtained has more
than that space, fix it.

This isn't a proper, final solution, as we need to support larger
events, but for the time being we at least bounds check and document it.

Fixes: 877108e42b1b9ba6 ("perf tools: Initial python binding")
Signed-off-by: Arnaldo Carvalho de Melo 
Reviewed-by: Ian Rogers 
Link: https://lore.kernel.org/r/20250312203141.285263-7-acme@kernel.org
Signed-off-by: Namhyung Kim

perf python: Don't keep a raw_data pointer to consumed ring buffer space

2025-03-18T23:08:35+00:00

When processing tracepoints the perf python binding was parsing the
event before calling perf_mmap__consume(&md->core) in
pyrf_evlist__read_on_cpu().

But part of this event parsing was to set the perf_sample->raw_data
pointer to the payload of the event, which then could be overwritten by
other event before tracepoint fields were asked for via event.prev_comm
in a python program, for instance.

This also happened with other fields, but strings were were problems
were surfacing, as there is UTF-8 validation for the potentially garbled
data.

This ended up showing up as (with some added debugging messages):

  ( field 'prev_comm' ret=0x7f7c31f65110, raw_size=68 )  ( field 'prev_pid' ret=0x7f7c23b1bed0, raw_size=68 )  ( field 'prev_prio' ret=0x7f7c239c0030, raw_size=68 )  ( field 'prev_state' ret=0x7f7c239c0250, raw_size=68 ) time 14771421785867 prev_comm= prev_pid=1919907691 prev_prio=796026219 prev_state=0x303a32313175 ==>
  ( XXX '��' len=16, raw_size=68)  ( field 'next_comm' ret=(nil), raw_size=68 ) Traceback (most recent call last):
   File "/home/acme/git/perf-tools-next/tools/perf/python/tracepoint.py", line 51, in 
     main()
   File "/home/acme/git/perf-tools-next/tools/perf/python/tracepoint.py", line 46, in main
     event.next_comm,
     ^^^^^^^^^^^^^^^
  AttributeError: 'perf.sample_event' object has no attribute 'next_comm'

When event.next_comm was asked for, the PyUnicode_FromString() python
API would fail and that tracepoint field wouldn't be available, stopping
the tools/perf/python/tracepoint.py test tool.

But, since we already do a copy of the whole event in pyrf_event__new,
just use it and while at it remove what was done in in e8968e654191390a
("perf python: Fix pyrf_evlist__read_on_cpu event consuming") because we
don't really need to wait for parsing the sample before declaring the
event as consumed.

This copy is questionable as is now, as it limits the maximum event +
sample_type and tracepoint payload to sizeof(union perf_event), this all
has been "working" because 'struct perf_event_mmap2', the largest entry
in 'union perf_event' is:

  $ pahole -C perf_event ~/bin/perf | grep mmap2
	struct perf_record_mmap2   mmap2;              /*     0  4168 */
  $

Fixes: bae57e3825a3dded ("perf python: Add support to resolve tracepoint fields")
Signed-off-by: Arnaldo Carvalho de Melo 
Reviewed-by: Ian Rogers 
Link: https://lore.kernel.org/r/20250312203141.285263-6-acme@kernel.org
Signed-off-by: Namhyung Kim

perf python: Decrement the refcount of just created event on failure

2025-03-18T23:08:29+00:00

To avoid a leak if we have the python object but then something happens
and we need to return the operation, decrement the offset of the newly
created object.

Fixes: 377f698db12150a1 ("perf python: Add struct evsel into struct pyrf_event")
Signed-off-by: Arnaldo Carvalho de Melo 
Reviewed-by: Ian Rogers 
Link: https://lore.kernel.org/r/20250312203141.285263-5-acme@kernel.org
Signed-off-by: Namhyung Kim

perf python: Remove some unused macros (_PyUnicode_FromString(arg), etc)

2025-03-18T23:08:14+00:00

When python2 support was removed in e7e9943c87d857da ("perf python:
Remove python 2 scripting support"), all use of the
_PyUnicode_FromString(arg), _PyUnicode_FromFormat(...), and
_PyLong_FromLong(arg) macros was removed as well, so remove it.

Signed-off-by: Arnaldo Carvalho de Melo 
Reviewed-by: Ian Rogers 
Link: https://lore.kernel.org/r/20250312203141.285263-3-acme@kernel.org
Signed-off-by: Namhyung Kim

perf python: Fixup description of sample.id event member

2025-03-18T23:08:05+00:00

Some old cut'n'paste error, its "ip", so the description should be
"event ip", not "event type".

Fixes: 877108e42b1b9ba6 ("perf tools: Initial python binding")
Signed-off-by: Arnaldo Carvalho de Melo 
Reviewed-by: Ian Rogers 
Link: https://lore.kernel.org/r/20250312203141.285263-2-acme@kernel.org
Signed-off-by: Namhyung Kim

perf python: Add evlist.config to set up record options

2025-03-12T01:55:38+00:00

Add access to evlist__config that is used to configure an evlist with
record options.

Reviewed-by: Howard Chu 
Signed-off-by: Ian Rogers 
Acked-by: Arnaldo Carvalho de Melo 
Link: https://lore.kernel.org/r/20250228222308.626803-11-irogers@google.com
Signed-off-by: Namhyung Kim

perf python: Add evlist all_cpus accessor

2025-03-12T01:55:38+00:00

Add a means to get the reference counted all_cpus CPU map from an
evlist in its python form.

Reviewed-by: Howard Chu 
Signed-off-by: Ian Rogers 
Reviewed-by: Arnaldo Carvalho de Melo 
Link: https://lore.kernel.org/r/20250228222308.626803-10-irogers@google.com
Signed-off-by: Namhyung Kim

perf python: Avoid duplicated code in get_tracepoint_field

2025-03-12T01:55:38+00:00

The code replicates computations done in evsel__tp_format, reuse
evsel__tp_format to simplify the python C code.

Reviewed-by: Howard Chu 
Signed-off-by: Ian Rogers 
Reviewed-by: Arnaldo Carvalho de Melo 
Link: https://lore.kernel.org/r/20250228222308.626803-9-irogers@google.com
Signed-off-by: Namhyung Kim

perf python: Update ungrouped evsel leader in clone

2025-03-12T01:55:37+00:00

evsels are cloned in the python code as they form part of the Python
object pyrf_evsel. The cloning doesn't update the evsel's leader, do
this for the case of an evsel being ungrouped.

Reviewed-by: Howard Chu 
Signed-off-by: Ian Rogers 
Reviewed-by: Arnaldo Carvalho de Melo 
Link: https://lore.kernel.org/r/20250228222308.626803-8-irogers@google.com
Signed-off-by: Namhyung Kim

perf python: Add optional cpus and threads arguments to parse_events

2025-03-12T01:55:37+00:00

Used for the evlist initialization.

Reviewed-by: Howard Chu 
Signed-off-by: Ian Rogers 
Reviewed-by: Arnaldo Carvalho de Melo 
Link: https://lore.kernel.org/r/20250228222308.626803-7-irogers@google.com
Signed-off-by: Namhyung Kim