-fno-omit-frame-pointer is not enough to make every target walkable by the
simple manual frame pointer unwinder.
The helper used by test_frame_pointer_unwind used to assume the frame pointer
named a two-word record where fp[0] was the previous frame pointer and fp[1]
was the return address. That is only the generic layout used by some targets.
This patch keeps that default, but moves the slots behind named offsets so
architecture-specific layouts can describe where the backchain and return
address really live.
On s390x, GCC and Clang do not emit a usable backchain unless -mbackchain is
enabled. Without it, the unwinder stops at the current C frame and the test
reports no Python frames. Once backchains are present, the helper must also
stop at the current thread's known C stack bounds; otherwise it can follow the
final backchain far enough to dereference an invalid frame and segfault.
For Linux s390x backchain frames, the documented z/Architecture stack-frame
layout saves r14, the return-address register, at byte offset 112 from the
frame pointer, so read the return address from that named slot instead of fp[1].
The 112-byte offset comes from Linux's s390 debugging documentation: its Stack
Frame Layout table shows z/Architecture backchain frames with the backchain at
offset 0 and saved r14 of the caller function at offset 112:
https://www.kernel.org/doc/html/v5.3/s390/debugging390.html#stack-frame-layout
This helper remains scoped to Linux s390x backchain frames. GNU SFrame's s390x
notes state that the s390x ELF ABI does not generally mandate where RA and FP
are saved, or whether they are saved at all:
https://sourceware.org/binutils/docs/sframe-spec.html#s390x
As Jens Remus noted, -fno-omit-frame-pointer is not needed when -mbackchain is
present.
On 32-bit ARM, GCC defaults to Thumb mode on common armhf toolchains. The Thumb
prologue keeps the saved frame pointer and link register at offsets that depend
on the generated frame, which breaks the fp[0]/fp[1] walk used by the helper.
Use -marm when it is supported for frame-pointer builds, and teach the helper
the GCC ARM-mode slots where the previous frame pointer is at fp[-1] and the
saved LR return address is at fp[0].
Co-authored-by: Petr Viktorin <encukou@gmail.com>
Co-authored-by: Victor Stinner <vstinner@python.org>
The remote debugging protocol has been generating spurious
vulnerability reports from automated scanners that pattern-match
on "remote access" and "memory operations" without understanding
the privilege model. This section documents the security boundaries
so reporters can self-triage before submitting.
The threat model clarifies three points: attaching requires the
same OS-level privileges as GDB (ptrace, task_for_pid, or
SeDebugPrivilege), crashes caused by reading corrupted target
process memory are not security issues, and a compromised target
process is out of scope. A subsection explains when operators
should use PYTHON_DISABLE_REMOTE_DEBUG for defence-in-depth.
Add a warning in the free-threading extensions howto explaining that
PyObject.ob_mutex is reserved for the critical section API and must not
be locked directly with PyMutex_Lock, as this can cause deadlocks.
Extension authors who need their own lock should add a separate PyMutex
field to their object struct.
Also add an ob_mutex member entry under PyObject in the C API reference
(Doc/c-api/structures.rst) with a cross-reference to the howto.
Co-authored-by: Victor Stinner <vstinner@python.org>
To avoid duplicate content in the Enum HOWTO and
API documentation which is not automatically synced,
the section about supported __dunder__ and _sunder
names is moved from HOWTO to API docs.
See also https://github.com/python/cpython/pull/136791
Although PEP 768 mentions how to disable the mechanism of
remote debugging, it is not documented in the Python docs.
This change adds a note on how to disable remote debugging support
in a Python interpreter to the remote debugging how-to.
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
* gh-140550: PEP 793 reference documentation
Since the PEP calls for soft-deprecation of the existing initialization
function, this reorganizes the relevant docs to put the new way of
doing things first, and de-emphasize the old.
Some bits, like the tutorial, are left out of this patch. (See the
issue for a list.)
* Docs: Move Enum functions and add examples
When the `Enum` functions `_add_alias_` and `_add_value_alias_` were added in de6bca9564, the documentation for them was done under `EnumType` instead of `Enum`.
This change moves them to the docs of the `Enum` class and adds an example for each function.
---------
Co-authored-by: Ethan Furman <ethan@stoneleaf.us>
* - Add an explainer guide (aka HOWTO, not how-to) for asyncio.
* Fix linter errors.
* - Enforce max line length of roughly 79 chars.
- Start sentences on new lines to minimize disruption of diffs.
* Add reference to subinterpreters.
* - Significantly reduce article size. Remove both example sections & "Which concurrency do I want" section.
* Align section-header lengths with section names.
* - Remove reference to deleted section.
* - Fix a variety of rote style guide items like title-alignment, use of ie and $, and so forth.
- Add links to other parts of the docs for keywords and objects like await, coro, task, future, etc.
* - One last title alignment.
* - Style nit.
* - Rework a variety of I statements.
* Lint fix.
* - Firm up commentary on yield from in corotuines.
* Update language comparing await and yield from.
* - Remove await-ing Tasks and futures section
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* - Address comments related to style & writing flow.
* per-thread event loop note.
* Add section describing coroutines roots in generators.
* Phrasing tweak.
* Use asyncio.create_task instead of asyncio.Task
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* small phrasing.
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* phrasing nit.
* style nits
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* phrasing nit
* Fix misnaming of async generator.
* phrasing nits.
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* consistent spacing
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* phrasing nits
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* add conclusion
* nits
* - Variety of style & grammar improvements thanks to ZeroIntensity's comments.
* - Make all directives start with a 3 space indent. Then 4 thereafter.
* - Use :linenos: instead of manually writing the line numbers.
* - Fix label typo for article.
* fix label link.
* Apply suggestions from code review
Co-authored-by: 🇺🇦 Sviatoslav Sydorenko (Святослав Сидоренко) <wk.cvs.github@sydorenko.org.ua>
Co-authored-by: Carol Willing <carolcode@willingconsulting.com>
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* - introduce async-sleep name
* Phrasing
* nit
* ungendered octopus
* teammates
* jobs
* rework fella to penguin
* - remove byline; add seealso
* Change ref from asyncio to use seealso block.
* Remove typehints. Fix indentation in one code example.
* Slight rephrase for clarity.
* Make references point to asyncio. Wrap some long lines.
* - Variety of style/phrasing improvements based on PR feedback.
* phrasing.
* phrasing nit.
* Apply suggestions from code review
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Carol Willing <carolcode@willingconsulting.com>
* nit
* Apply suggestions from code review
Co-authored-by: Carol Willing <carolcode@willingconsulting.com>
* fix backticks.
* nits
* nit
* add section on asyncio.run
* title change under the hood.
* modify task coro example.
* howtos article link.
* prefer await without backticks.
* phrasing tweak.
* Rework phrasing around how await tasks pauses and returns control in the await section.
* move code block to beforfe explanation in coroutine under the hood.
* phrasing.
* link to yield from.
* style nits
* nit
* - Modify language re: event-loop cycling endlessly.
- Discuss why await was designed to not yield for coros.
* - Add a note about debug=True on asyncio.run to await coro section.
* clarity nit
* - Add two other references in seealso block.
* nit
* Language simplification
* Apply suggestions from code review
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
* nit
* grammar fix.
* fix
* worker bees
* rework event loop paragraph to significantly deemphasize queues
* remove all references to queue besides the initial analogy.
* add note about garbage collection of tasks
* add practical note re: garbage collection
* phrasing nits
* re arrange note on task gc.
* line wrap nit
* Update Doc/howto/a-conceptual-overview-of-asyncio.rst
Co-authored-by: Kumar Aditya <kumaraditya@python.org>
* link to debug mode docs.
* readd part2 prefix.
* simplify title.
* fix titles. tihnk I messed this up earlier.
* avoid idiom in title.
* fix titles once agian.
* Apply suggestions from code review
Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>
* rework task gc example.
* phrasing tweak.
* tewak.
* nit
* nit
* nit
* nit
---------
Co-authored-by: Peter Bierma <zintensitydev@gmail.com>
Co-authored-by: 🇺🇦 Sviatoslav Sydorenko (Святослав Сидоренко) <wk.cvs.github@sydorenko.org.ua>
Co-authored-by: Carol Willing <carolcode@willingconsulting.com>
Co-authored-by: Kumar Aditya <kumaraditya@python.org>
Co-authored-by: Stan Ulbrych <89152624+StanFromIreland@users.noreply.github.com>
The documentation incorrectly stated that generator.close() 'raises' a
GeneratorExit exception. This was misleading because the method doesn't
raise the exception to the caller - it sends the exception internally
to the generator and returns None.
Peter Bierma