mirror of
https://github.com/python/cpython.git
synced 2026-06-05 01:10:53 +00:00
4ed40146f1
-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> |
||
|---|---|---|
| .. | ||
| _static | ||
| c-api | ||
| data | ||
| deprecations | ||
| distributing | ||
| extending | ||
| faq | ||
| howto | ||
| includes | ||
| installing | ||
| library | ||
| reference | ||
| tools | ||
| tutorial | ||
| using | ||
| whatsnew | ||
| .ruff.toml | ||
| about.rst | ||
| bugs.rst | ||
| conf.py | ||
| constraints.txt | ||
| contents.rst | ||
| copyright.rst | ||
| glossary.rst | ||
| improve-page-nojs.rst | ||
| improve-page.rst | ||
| license.rst | ||
| make.bat | ||
| Makefile | ||
| pylock.toml | ||
| README.rst | ||
| requirements.txt | ||
Python Documentation README ~~~~~~~~~~~~~~~~~~~~~~~~~~~ This directory contains the reStructuredText (reST) sources to the Python documentation. You don't need to build them yourself, `prebuilt versions are available <https://docs.python.org/dev/download.html>`_. Documentation on authoring Python documentation, including information about both style and markup, is available in the "`Documenting Python <https://devguide.python.org/documenting/>`_" chapter of the developers guide. Building the docs ================= The documentation is built with several tools which are not included in this tree but are maintained separately and are available from `PyPI <https://pypi.org/>`_. * `Sphinx <https://pypi.org/project/Sphinx/>`_ * `blurb <https://pypi.org/project/blurb/>`_ * `python-docs-theme <https://pypi.org/project/python-docs-theme/>`_ The easiest way to install these tools is to create a virtual environment and install the tools into there. Using make ---------- To get started on Unix, you can create a virtual environment and build documentation with the commands:: make venv make html The virtual environment in the ``venv`` directory will contain all the tools necessary to build the documentation downloaded and installed from PyPI. If you'd like to create the virtual environment in a different location, you can specify it using the ``VENVDIR`` variable. You can also skip creating the virtual environment altogether, in which case the ``Makefile`` will look for instances of ``sphinx-build`` and ``blurb`` installed on your process ``PATH`` (configurable with the ``SPHINXBUILD`` and ``BLURB`` variables). On Windows, we try to emulate the ``Makefile`` as closely as possible with a ``make.bat`` file. If you need to specify the Python interpreter to use, set the ``PYTHON`` environment variable. Available make targets are: * "clean", which removes all build files and the virtual environment. * "clean-venv", which removes the virtual environment directory. * "venv", which creates a virtual environment with all necessary tools installed. * "html", which builds standalone HTML files for offline viewing. * "htmlview", which re-uses the "html" builder, but then opens the main page in your default web browser. * "htmllive", which re-uses the "html" builder, rebuilds the docs, starts a local server, and automatically reloads the page in your browser when you make changes to reST files (Unix only). * "htmlhelp", which builds HTML files and a HTML Help project file usable to convert them into a single Compiled HTML (.chm) file -- these are popular under Microsoft Windows, but very handy on every platform. To create the CHM file, you need to run the Microsoft HTML Help Workshop over the generated project (.hhp) file. The ``make.bat`` script does this for you on Windows. * "latex", which builds LaTeX source files as input to ``pdflatex`` to produce PDF documents. * "text", which builds a plain text file for each source file. * "epub", which builds an EPUB document, suitable to be viewed on e-book readers. * "linkcheck", which checks all external references to see whether they are broken, redirected or malformed, and outputs this information to stdout as well as a plain-text (.txt) file. * "changes", which builds an overview over all versionadded/versionchanged/ deprecated items in the current version. This is meant as a help for the writer of the "What's New" document. * "coverage", which builds a coverage overview for standard library modules and C API. * "pydoc-topics", which builds a Python module containing a dictionary with plain text documentation for the labels defined in ``tools/pyspecific.py`` -- pydoc needs these to show topic and keyword help. * "check", which checks for frequent markup errors. * "dist", (Unix only) which creates distributable archives of HTML, text, PDF, and EPUB builds. Without make ------------ First, install the tool dependencies from PyPI. Then, from the ``Doc`` directory, run :: sphinx-build -b<builder> . build/<builder> where ``<builder>`` is one of html, text, latex, or htmlhelp (for explanations see the make targets above). Deprecation header ================== You can define the ``outdated`` variable in ``html_context`` to show a red banner on each page redirecting to the "latest" version. The link points to the same page on ``/3/``, sadly for the moment the language is lost during the process. Contributing ============ Bugs in the content should be reported to the `Python bug tracker <https://github.com/python/cpython/issues>`_. Bugs in the toolset should be reported to the tools themselves. To help with the documentation, or report any problems, please leave a message on `discuss.python.org <https://discuss.python.org/c/documentation>`_.