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Programmable debugger
add17a9a36
dwfl_module_getsrc() relies on .debug_aranges to find the CU containing the PC. If the module has a missing or incomplete .debug_aranges, it fails. This lookup is actually redundant since we already found the CU when we unwound the stack. Use the libdw helpers that take the CU DIE instead to avoid this. We also need to save the CU for frames where we found it but couldn't find the subprogram (typically assembly files). Signed-off-by: Omar Sandoval <osandov@osandov.com> |
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.github/workflows | ||
docs | ||
drgn | ||
examples/linux | ||
libdrgn | ||
scripts | ||
tests | ||
tools | ||
vmtest | ||
_drgn.pyi | ||
.editorconfig | ||
.git-blame-ignore-revs | ||
.gitignore | ||
.readthedocs.yml | ||
CONTRIBUTING.rst | ||
COPYING | ||
MANIFEST.in | ||
pyproject.toml | ||
README.rst | ||
setup.py | ||
util.py |
drgn ==== .. image:: https://img.shields.io/pypi/v/drgn :target: https://pypi.org/project/drgn/ :alt: PyPI .. image:: https://github.com/osandov/drgn/workflows/CI/badge.svg :target: https://github.com/osandov/drgn/actions :alt: CI Status .. image:: https://readthedocs.org/projects/drgn/badge/?version=latest :target: https://drgn.readthedocs.io/en/latest/?badge=latest :alt: Documentation Status .. image:: https://img.shields.io/badge/code%20style-black-000000.svg :target: https://github.com/psf/black .. start-introduction drgn (pronounced "dragon") is a debugger with an emphasis on programmability. drgn exposes the types and variables in a program for easy, expressive scripting in Python. For example, you can debug the Linux kernel: .. code-block:: pycon >>> from drgn.helpers.linux import list_for_each_entry >>> for mod in list_for_each_entry('struct module', ... prog['modules'].address_of_(), ... 'list'): ... if mod.refcnt.counter > 10: ... print(mod.name) ... (char [56])"snd" (char [56])"evdev" (char [56])"i915" Although other debuggers like `GDB <https://www.gnu.org/software/gdb/>`_ have scripting support, drgn aims to make scripting as natural as possible so that debugging feels like coding. This makes it well-suited for introspecting the complex, inter-connected state in large programs. It is also designed as a library that can be used to build debugging and introspection tools; see the official `tools <https://github.com/osandov/drgn/tree/main/tools>`_. drgn was developed for debugging the Linux kernel (as an alternative to the `crash <http://people.redhat.com/anderson/>`_ utility), but it can also debug userspace programs written in C. C++ support is in progress. .. end-introduction Documentation can be found at `drgn.readthedocs.io <https://drgn.readthedocs.io>`_. Installation ------------ .. start-install-dependencies Install dependencies: Arch Linux: .. code-block:: console $ sudo pacman -S --needed gcc libelf make pkgconf python python-pip python-setuptools Debian/Ubuntu: .. code-block:: console $ sudo apt-get install gcc liblzma-dev libelf-dev libdw-dev make pkgconf python3 python3-dev python3-pip python3-setuptools zlib1g-dev Note that Debian Stretch, Ubuntu Trusty, and Ubuntu Xenial (and older) ship Python versions which are too old. Python 3.6 or newer must be installed manually. Fedora: .. code-block:: console $ sudo dnf install elfutils-devel gcc make pkgconf python3 python3-devel python3-pip python3-setuptools Optionally, install: * `libkdumpfile <https://github.com/ptesarik/libkdumpfile>`_ if you want support for kdump-compressed kernel core dumps .. end-install-dependencies Then, run: .. code-block:: console $ sudo pip3 install drgn See the `installation documentation <https://drgn.readthedocs.io/en/latest/installation.html>`_ for more options. Quick Start ----------- .. start-quick-start drgn debugs the running kernel by default; run ``sudo drgn``. To debug a running program, run ``sudo drgn -p $PID``. To debug a core dump (either a kernel vmcore or a userspace core dump), run ``drgn -c $PATH``. The program must have debugging symbols available. Then, you can access variables in the program with ``prog['name']``, access structure members with ``.``, use various predefined helpers, and more: .. code-block:: pycon $ sudo drgn >>> prog['init_task'].comm (char [16])"swapper/0" >>> d_path(fget(find_task(prog, 1), 0).f_path.address_of_()) b'/dev/null' >>> max(task.stime for task in for_each_task(prog)) (u64)4192109975952 >>> sum(disk.gendisk.part0.nr_sects for disk in for_each_disk(prog)) (sector_t)999705952 .. end-quick-start See the `user guide <https://drgn.readthedocs.io/en/latest/user_guide.html>`_ for more information. License ------- .. start-license Copyright (c) Facebook, Inc. and its affiliates. drgn is licensed under the `GPLv3 <https://www.gnu.org/licenses/gpl-3.0.en.html>`_ or later. .. end-license