[PATCH v17 00/20] Add additional python API support

[Ian Rogers]

The perf script command has long supported running Python and Perl scripts
by embedding libpython and libperl. This approach has several drawbacks:
 - overhead by creating Python dictionaries for every event (whether used or
   not),
 - complex build dependencies on specific Python/Perl versions,
 - complications with threading due to perf being the interpreter,
 - no clear way to run standalone scripts like ilist.py.

This series takes a different approach with some initial implementation posted
as an RFC last October:
https://lore.kernel.org/linux-perf-users/20251029053413.355154-1-irogers@xxxxxxxxxx/
with the motivation coming up on the mailing list earlier:
https://lore.kernel.org/lkml/CAP-5=fWDqE8SYfOLZkg_0=4Ayx6E7O+h7uUp4NDeCFkiN4b7-w@xxxxxxxxxxxxxx/

The ultimate goal is to remove the embedded libpython and libperl support from
perf entirely, expanding the existing perf Python module to provide full access
to perf data files and events, allowing scripts to be run as standalone Python
applications.

To make the review process more manageable, the original 58-patch series has
been split. This v17 series represents "Phase 1: API & Infrastructure" (20 patches).
The first 4 patches of Phase 1 (cleanups and arch-specific header sorting) have
already been merged upstream.

This remaining set contains:
1. Missed explicit dependency cleanups and header sorting for util/ and python.
2. Crucial core safety infrastructure (reference counting for evlist/evsel)
   to support safe lifecycle management in garbage-collected Python.
3. The core Python API extensions (session wrappers, perf_data wrappers,
   sample accessors, stubs, and LiveSession helper).

The subsequent "Phase 2" series will contain the actual porting of all
existing Python/Perl scripts to the new API (which yields up to 35x speedups
as demonstrated previously) and the final removal of embedded interpreters.


Addressing v16 Review Feedback:
 - Patch 10: Removed unconditional `perf_session__create_kernel_maps` to
   prevent corrupting cross-platform offline analysis.
 - Patch 11: Corrected inaccurate commit message regarding memory
   allocation sizing.
 - Patch 19: Fixed numerous type inconsistencies, missing properties, and
   incorrect return types in the `perf.pyi` stubs file.
 - Patch 20: Cleaned up unused `import errno` in `perf_live.py`.

Note: Several issues spotted in v16 review (e.g. pyrf_evsel__init format
string type mismatch, evlist lockless double free, asymmetric memory
leaks, and lack of NUL-termination for COMM/MMAP) are pre-existing
limitations in the codebase or side-effects of the transitional
cycle-breaking design. As discussed previously, these structurally complex
or pre-existing bugs are deliberately deferred to the Phase 2 series.

Addressing v15 Review Feedback:
- Patch 2 (buffer overflow & type checks): The buffer overflow in
  pyrf_counts_values_set_values and unsafe PyArg_ParseTupleAndKeywords
  casts are pre-existing issues in tools/perf/util/python.c. To keep
  Phase 1 scoped strictly to new API infrastructure, these will be
  followed up and fixed independently during Phase 2.
- Patch 7 (evlist refcounting): The TOCTOU race condition and asymmetric
  drop cycle-leak mentioned in the review are known limitations of this
  transitional cycle-breaking logic. A proper, thread-safe fix requires a
  global design change that is out of scope for Phase 1. These structural
  cycle-breaking issues will be fully addressed in Phase 2.
- Patch 16 (syscall name/id): The script modifications (syscall-counts.py)
  are intentionally omitted from this patch. As stated, the porting of
  scripts to the new API will be done entirely in Phase 2. The commit
  message simply motivates the API addition.

---


v16 Changes
-----------
- Patch 6: Added missing CHECK_INITIALIZED for pevsel parameter in
  pyrf_evlist__add and added evsel__put(pevent->evsel) to
  pyrf_sample_event__delete to fix a git bisect reference leak.
- Patch 11: Restored the TypeError for oversized events instead of
  silently truncating them and causing memory corruption. Also added
  specific handling for -EAGAIN in pyrf_evlist__read_on_cpu to return
  Py_RETURN_NONE instead of raising OSError.
- Patch 12: Added explicit null-termination for the mmap2 filename to
  prevent heap out-of-bounds reads when accessed via T_STRING_INPLACE.
- Patch 14: Removed the fallback to perf_event__process_stat_event when
  no stat callback is provided, preventing a segmentation fault on
  PERF_RECORD_STAT events.
- Patch 18: Added a new patch 'perf python: Handle Py_None for thread
  and cpu maps' to fix a pre-existing C API bug where passing None
  from Python caused a crash. This addresses the feedback on the stubs.

v15 Changes
-----------
- Patch 11: Removed manual '\0' assignment for mmap/comm filenames which
  corrupted the sample_id trailer. Replaced with memset of the event buffer
  prior to memcpy to safely handle non-terminated strings without
  overwriting trailer data.
- Patch 18: Added python/perf.pyi to Makefile.perf dependencies. Added
  missing properties to counts_values and sample_event stubs, fixed
  branch_stack/callchain sequence protocols, and added _sample_members
  inheritance to stat_round_event in perf.pyi.

v14 Changes
-----------
- Patch 6: Replaced Py_IsTrue with PyObject_IsTrue to correctly evaluate
  Python truthiness and added error handling returning -1.
- Patch 7: Added comments to `evlist__put` and `evlist__splice_list_tail`
  noting that cycle breaking and pointer rebinding for spliced events will
  be addressed in subsequent patches. Removed "Phase 2" from the previous
  cycle-breaking comment as it doesn't make sense in the wider Linux code
  base context.
- Patch 10: Fixed `pyrf_session__new` missing `tool.tracing_data`
  initialization and wrapped kernel map creation in an access check.
- Patch 15: Exposed remaining bitfields from `struct branch_flags` in
  `pyrf_branch_entry`.
- Patch 18: Cleaned up `perf.pyi` in `Makefile.perf`'s `python-clean`
  target. Renamed `sc_id` to `id` in `syscall_name` stub, and corrected
  property types.
- Patch 19: Fixed `perf_live.py` inner loop to `break` instead of
  `continue` on `TypeError` to properly exit when processing is complete.

v13 Changes
-----------
- Patch 6: Reverted `idx` parsing for `pyrf_evsel__init`. Added explicit NULL
  checks for `evlist` in `session.c` to prevent crashes when accessing properties.
- Patch 7: Rely natively on `evlist.c`'s updated logic through `evlist__add`.
- Patch 8: Fixed memory leak in `intel_pt_synth_ptwrite_sample` by adding
  `perf_sample__exit(&sample)` on exit.
- Patch 9: Zeroed out `perf_data` struct via `memset(&data, 0, sizeof(data))`
  before using it to prevent stale state issues.
- Patch 11: Switched from `PyLong_FromUnsignedLong` to `PyLong_FromUnsignedLongLong`
  to guarantee full 64-bit bounds representation even on 32-bit platforms.
- Patch 18: Modified `Makefile.perf` to correctly install `perf.pyi`.
  Synchronized `.pyi` stubs to fully match the C implementation signatures.
- Patch 19: Updated `pyrf_evlist__read_on_cpu` to safely return `Py_RETURN_NONE`
  on `-EAGAIN` natively from C instead of relying on broken OSError emulation.
  Updated `perf_live.py` loop to handle the native `None` return correctly.

v12 Changes
-----------
- Patch 6: Restored `idx` parsing in `pyrf_evsel__init` kwargs, and removed
  an erroneous `Py_INCREF(pevsel)` in `pyrf_evlist__add` that caused a
  memory leak.
- Patch 7: Fixed `evlist__put` cycle collection TOCTOU double free race by
  checking `refcount_read == 1`. Fixed `evlist__purge` recursion and cycle
  reference tearing logic.
- Patch 8: Removed an extra `evsel__get` in `evsel__parse_sample` to fix a
  reference leak on error paths.
- Patch 11: Used `copy_size` to bound `max_len` for NUL termination to fix
  an out-of-bounds write in `pyrf_event__new`. Also set
  `pevent->event.header.size = copy_size`.
- Patch 12: Used `copy_size` to bound `max_len` for NUL termination of
  mmap2 and comm events to fix an out-of-bounds write.
- Patch 13: Added an optional `struct machine *` argument to
  `pyrf_event__new` defaulting to the host machine if NULL, avoiding
  regressions for future phases.
- Patch 14: Made `psession->tool.stat = perf_event__process_stat_event;`
  conditional on `!stat` so it doesn't unconditionally overwrite user stat
  callbacks.
- Patch 18: Audited all `perf.pyi` event stubs: added full `sample_members`
  attributes (`pid`, `tid`, `time`, `id`, `stream_id`, `period`, `cpu`) to
  all payload events via inheritance. Fixed `sample_event` unique fields
  (`ip`, `addr`, `phys_addr`, `weight`, `data_src`, `insn_cnt`, `cyc_cnt`).
  Renamed `mmap_event.addr` to `start`. Removed `read_event.value`.
- Patch 19: Replaced `except TypeError` with `continue` to ignore
  unmapped/offline CPUs instead of breaking the poll loop. Replaced
  hardcoded `-11` with `e.errno == errno.EAGAIN` in `LiveSession.run()`.
  Fixed `setup_python.sh` `PYTHONPATH` prepend logic to cleanly append to
  existing paths.

Ian Rogers (20):
  perf util: Sort includes and add missed explicit dependencies
  perf python: Add missed explicit dependencies
  perf evsel/evlist: Avoid unnecessary #includes
  perf data: Add open flag
  perf evlist: Add reference count
  perf evsel: Add reference count
  perf evlist: Add reference count checking
  perf python: Use evsel in sample in pyrf_event
  perf python: Add wrapper for perf_data file abstraction
  perf python: Add python session abstraction wrapping perf's session
  perf python: Refactor and add accessors to sample event
  perf python: Add mmap2 event
  perf python: Add callchain support
  perf python: Extend API for stat events in python.c
  perf python: Expose brstack in sample event
  perf python: Add syscall name/id to convert syscall number and name
  perf python: Add config file access
  perf python: Handle Py_None for thread and cpu maps
  perf python: Add perf.pyi stubs file
  perf python: Add LiveSession helper

 tools/perf/Makefile.perf                    |    9 +-
 tools/perf/arch/arm/util/cs-etm.c           |   10 +-
 tools/perf/arch/arm64/util/arm-spe.c        |    8 +-
 tools/perf/arch/arm64/util/hisi-ptt.c       |    2 +-
 tools/perf/arch/x86/tests/hybrid.c          |   22 +-
 tools/perf/arch/x86/tests/topdown.c         |    4 +-
 tools/perf/arch/x86/util/auxtrace.c         |    2 +-
 tools/perf/arch/x86/util/intel-bts.c        |    6 +-
 tools/perf/arch/x86/util/intel-pt.c         |    9 +-
 tools/perf/arch/x86/util/iostat.c           |   14 +-
 tools/perf/bench/evlist-open-close.c        |   29 +-
 tools/perf/builtin-annotate.c               |    7 +-
 tools/perf/builtin-ftrace.c                 |   14 +-
 tools/perf/builtin-inject.c                 |    9 +-
 tools/perf/builtin-kvm.c                    |   14 +-
 tools/perf/builtin-kwork.c                  |    8 +-
 tools/perf/builtin-lock.c                   |    4 +-
 tools/perf/builtin-record.c                 |   95 +-
 tools/perf/builtin-report.c                 |    6 +-
 tools/perf/builtin-sched.c                  |   30 +-
 tools/perf/builtin-script.c                 |   15 +-
 tools/perf/builtin-stat.c                   |   83 +-
 tools/perf/builtin-top.c                    |  104 +-
 tools/perf/builtin-trace.c                  |   65 +-
 tools/perf/python/perf.pyi                  |  654 +++++
 tools/perf/python/perf_live.py              |   55 +
 tools/perf/tests/backward-ring-buffer.c     |   26 +-
 tools/perf/tests/code-reading.c             |   14 +-
 tools/perf/tests/event-times.c              |    6 +-
 tools/perf/tests/event_update.c             |    4 +-
 tools/perf/tests/evsel-roundtrip-name.c     |    8 +-
 tools/perf/tests/evsel-tp-sched.c           |    4 +-
 tools/perf/tests/expand-cgroup.c            |   12 +-
 tools/perf/tests/hists_cumulate.c           |    2 +-
 tools/perf/tests/hists_filter.c             |    2 +-
 tools/perf/tests/hists_link.c               |    2 +-
 tools/perf/tests/hists_output.c             |    2 +-
 tools/perf/tests/hwmon_pmu.c                |    7 +-
 tools/perf/tests/keep-tracking.c            |   10 +-
 tools/perf/tests/mmap-basic.c               |   24 +-
 tools/perf/tests/openat-syscall-all-cpus.c  |    6 +-
 tools/perf/tests/openat-syscall-tp-fields.c |   26 +-
 tools/perf/tests/openat-syscall.c           |    6 +-
 tools/perf/tests/parse-events.c             |  139 +-
 tools/perf/tests/parse-metric.c             |    8 +-
 tools/perf/tests/parse-no-sample-id-all.c   |    2 +-
 tools/perf/tests/perf-record.c              |   38 +-
 tools/perf/tests/perf-time-to-tsc.c         |   12 +-
 tools/perf/tests/pfm.c                      |   12 +-
 tools/perf/tests/pmu-events.c               |   11 +-
 tools/perf/tests/pmu.c                      |    4 +-
 tools/perf/tests/sample-parsing.c           |   45 +-
 tools/perf/tests/shell/lib/setup_python.sh  |   13 +
 tools/perf/tests/sw-clock.c                 |   20 +-
 tools/perf/tests/switch-tracking.c          |   11 +-
 tools/perf/tests/task-exit.c                |   20 +-
 tools/perf/tests/time-utils-test.c          |   14 +-
 tools/perf/tests/tool_pmu.c                 |    7 +-
 tools/perf/tests/topology.c                 |    4 +-
 tools/perf/tests/uncore-event-sorting.c     |    6 +-
 tools/perf/ui/browsers/annotate.c           |    2 +-
 tools/perf/ui/browsers/hists.c              |   22 +-
 tools/perf/util/Build                       |    1 -
 tools/perf/util/amd-sample-raw.c            |    2 +-
 tools/perf/util/annotate-data.c             |    2 +-
 tools/perf/util/annotate.c                  |   10 +-
 tools/perf/util/auxtrace.c                  |   14 +-
 tools/perf/util/block-info.c                |    4 +-
 tools/perf/util/bpf_counter.c               |    2 +-
 tools/perf/util/bpf_counter_cgroup.c        |   14 +-
 tools/perf/util/bpf_ftrace.c                |    9 +-
 tools/perf/util/bpf_lock_contention.c       |   12 +-
 tools/perf/util/bpf_off_cpu.c               |   44 +-
 tools/perf/util/bpf_trace_augment.c         |    8 +-
 tools/perf/util/cgroup.c                    |   26 +-
 tools/perf/util/cs-etm.c                    |    5 +-
 tools/perf/util/data-convert-bt.c           |    2 +-
 tools/perf/util/data.c                      |   27 +-
 tools/perf/util/data.h                      |    4 +-
 tools/perf/util/evlist.c                    |  496 ++--
 tools/perf/util/evlist.h                    |  273 +-
 tools/perf/util/evsel.c                     |   39 +-
 tools/perf/util/evsel.h                     |   40 +-
 tools/perf/util/expr.c                      |    2 +-
 tools/perf/util/header.c                    |   69 +-
 tools/perf/util/header.h                    |    2 +-
 tools/perf/util/intel-pt.c                  |    2 +-
 tools/perf/util/intel-tpebs.c               |    7 +-
 tools/perf/util/iostat.c                    |    2 +-
 tools/perf/util/iostat.h                    |    2 +-
 tools/perf/util/map.h                       |    9 +-
 tools/perf/util/metricgroup.c               |   12 +-
 tools/perf/util/parse-events.c              |   10 +-
 tools/perf/util/parse-events.y              |    2 +-
 tools/perf/util/perf_api_probe.c            |   20 +-
 tools/perf/util/pfm.c                       |    4 +-
 tools/perf/util/print-events.c              |    2 +-
 tools/perf/util/python.c                    | 2633 ++++++++++++++++---
 tools/perf/util/record.c                    |   11 +-
 tools/perf/util/s390-sample-raw.c           |   20 +-
 tools/perf/util/sample-raw.c                |    4 +-
 tools/perf/util/sample.c                    |   17 +-
 tools/perf/util/session.c                   |   69 +-
 tools/perf/util/session.h                   |    2 +
 tools/perf/util/setup.py                    |    5 +
 tools/perf/util/sideband_evlist.c           |   40 +-
 tools/perf/util/sort.c                      |    2 +-
 tools/perf/util/stat-display.c              |    6 +-
 tools/perf/util/stat-shadow.c               |   24 +-
 tools/perf/util/stat.c                      |   20 +-
 tools/perf/util/stream.c                    |    4 +-
 tools/perf/util/synthetic-events.c          |   11 +-
 tools/perf/util/time-utils.c                |   12 +-
 tools/perf/util/top.c                       |    4 +-
 114 files changed, 4445 insertions(+), 1447 deletions(-)
 create mode 100644 tools/perf/python/perf.pyi
 create mode 100755 tools/perf/python/perf_live.py

-- 
2.54.0.1136.gdb2ca164c4-goog