CHANGELOG.md

Changelog

Unreleased

Changes which are committed to git, but not yet released, may appear here.

0.9.0 - Tue, Apr 16, 2023

This marks the final version before public release! The primary changes have to do with release preparation.

Added

• RPM spec file for packaging
• Manual page for corelens
• Corelens modules:
  • net
  • multipath (v2 only)
  • virtutil (v2 only)
• Corelens modules for v2 have been split off into the drgn_tools.v2 package. They will not be included in the v1 RPM.

Changed

• The required drgn version is 0.0.25 or 0.0.26.
• Corelens improvements to user experience:
  • When run with -o, corelens prints each module as it runs, along with runtime. This helps assure that progress is made. The timing information is also included in the report.
  • Additional information is provided to the user about each module: what kernel moudles it depends on, special debuginfo requirements, etc.
  • Corelens now checks whether CTF is compatible prior to loading it
• The lock module is improved to index stack traces for much faster runtime.
• The lock module now supports rwsem.
• The ps module has more command line arguments similar to crash's.

0.8.0 - Wed, Jan 31, 2023

Another intermediate release prior to 1.0.0. We have a few new corelens modules, and some fixes and general improvements.

Added

• slabinfo corelens module
• partitioninfo corelens module
• CtfCompatibility to automatically detect which UEK kernels are compatible with CTF debuginfo

Fixed

• bt corelens module is more resilient to unwind errors
• md helpers now support kernels containing a92ce0feffee ("md: drop queue limitation for RAID1 and RAID10"), from 5.17

Changed

• bt() function now outputs the task state in [] brackets as part of the header
• scsiinfo now outputs more useful fields
• Several minor improvements to testing infrastructure

0.7.0 - Tue, Jan 9, 2023

This is another intermediate release prior to the anticipated 1.0.0. It contains new corelens modules and an improved Corelens CLI, along with some bug and performance fixes.

Added

• Corelens modules & helpers added:
  • runq corelens module
  • lsmod corelens module
  • blockinfo corelens module
  • scsiinfo corelens module
  • filecache corelens module

Changed

• The ps corelens module now supports regular output fields
• The Corelens CLI has the following changes:
  • When run without args, shows a usage summary
  • When run without specifying modules, shows the sys output
  • The -a and -A arguments are used to run all modules
  • CTF is loaded automatically when DWARF is unavailable
• Corelens modules may now be skipped if they don't support live kernels

Fixed

• Performance issues related to have_debuginfo() is greatly reduced, especially when using CTF.
• Several block & NVME helpers are updated to work with RHCK 9.

0.6.0 - Tue, Dec 5, 2023

This is the first major release of drgn-tools after open-sourcing! We've been on a mission to add many Corelens modules, and so this release contains several of those. There are also lots of quality of life improvements and a few bug fixes. Since it's been almost three months since our last release, this is a bigger one. I hope to make releases a bit more frequently form here on out.

Added

• Added a -L option to corelens which lists all corelens modules alongside a brief description of each.
• Consistent with the new changes in drgn, we now can open /proc/kcore using sudo, without running drgn & drgn-tools as root.
• The "litevm" testing framework now runs in Github Actions!
• Support for aarch64 / arm64 is now available and tested!
• Corelens modules & helpers added:
  • drgn_tools.irq and irq corelens module
  • drgn_tools.cpuinfo and cpuinfo corelens module
  • dentrycache corelens module (most of the helpers were present in 0.5.1)
  • bt module (equivalent of crash's foreach bt)
  • drgn_tools.meminfo and meminfo corelens module (similar to /proc/meminfo)
  • drgn_tools.mounts and mounts corelens module (similar to /proc/mounts)
  • drgn_tools.task and ps corelens module (only supports ps -m for now)
  • drgn_tools.lock and lock corelens module (detecting contended semaphores and mutexes)
  • drgn_tools.numastat and numastat corelens module
  • drgn_tools.buddyinfo and buddyinfo corelens module
  • drgn_tools.nfs and nfs corelens module

Changed

• corelens: the --vmlinux argument has now become --debuginfo. This should instead specify a directory containing a vmlinux and any module .ko.debug files necessary to run.
• The required drgn version is 0.0.25.

Fixed

• corelens: modules are now specified using -M, just as the help output indicates. Previously they were specified using --.
• corelens: modules missing necessary debuginfo are now skipped. Previously, we logged an error, but continued to execute them anyway.

0.5.1 - Tue, Sept 12, 2023

In this release we have several new helpers, as well as a lot of changes in preparation for open-sourcing.

Added

• 0.5.1 patch adds an entry point for the "corelens" script.
• Debuginfo fetching API is added. An implementation which downloads from the public Yum debuginfo repositories is added. The debuginfo fetching is configurable via ~/.config/drgn_tools.ini.
• New testing framework, "litevm", enables testing drgn-tools without creating large VM images. This is suitable for use in environments like Github actions.
• New helpers
  • RDS
  • Dentry cache
  • File cache
  • Sysctl

Changed

• The required drgn version is 0.0.24.
• Existing VM testing framework has been renamed to "heavyvm".

0.4.0 - Thur, Jun 29, 2023

Added

• New md/raid helpers and corresponding corelens module.
• New RDS helper and corresponding corelens module.

Changed

• Test VMs are now updated to OL8.8 and OL9.2.
• The minimum requirement for drgn is not 0.0.23, the latest release.

Fixes

• Fix for the SMP CSD helpers.
• An optimization has been added to the symbol loader for modules which don't have debuginfoa available.

0.3.0 - Tue, May 23, 2023

Added

• The drgn_tools.corelens script has finally become more useful and less preliminary. This is intended to be an automatic mechanism for running analysis code and printing its results to either stdout, or to a sosreport-like directory.
  • The command line interface is changed & much improved from the preliminary version released in 0.2.0, thanks to feedback in the Drgn Biweekly meeting.
  • Helpers may implement Corelens "modules", which can then be executed on the command line with arguments, or executed automatically in bulk using their default arguments.
  • The Corelens system handles ensuring that debuginfo is loaded for the correct kernel modules. It defaults to using DWARF debuginfo, but it supports the new provisional CTF API provided by the internal Drgn builds.
  • Many pre-existing helpers now have corelens modules, as well as the newly added helper modules.
  • During interactive debugging, you may use the special function cl() function to execute a corelens command.
• Added the Ext4 Directory Lock scan, which can find tasks blocked on a particular directory inode and identify the current owner of the lock. This scan depends on DWARF debuginfo for finding variables from the stack trace. There is a Corelens module too. Thanks to Junxiao for these.
• Added helpers for the SMP IPI subsystem. These can show pending SMP function calls and help see which CPU is waiting on which others. There is a Corelens module as well. Thanks Imran for these!

Fixed

• The drgn_tools.debuginfo script now correctly outputs the filename vmlinux rather than vmlinux.ko.debug, as it did before.

0.2.0 - Tue, April 25, 2023

Added

• Added drgn_tools.debuginfo CLI script. This can be called with a UEK release string to find vmlinux, extracting it if necessary. In the process, it will also update the access time in the access.db file.
• Added the drgn_tools.taint module that has an enumeration of the module / kernel taint values. These aren't included in debuginfo due since they are preprocessor definitions.
• Added a preliminary system called corelens which will be able to run scripts against vmcores and live systems. For now, there's no major change introduced, and the system is just a sketch.

Changed

• drgn_tools.bt.bt() now has a show_absent flag -- and it is false by default. This is a breaking change, but I think a welcome one. There are more absent variables than non-absent in your average stack trace, and they take up a lot of space to show you absolutely nothing. So now, they are hidden by default to free up some real estate on your screen.
• drgn_tools.bt has now been refactored into several helper functions. Please see the module documentation for more information. TL;DR: if you wanted to get expanded stack trace frames, without printing them, you're now in luck!

Fixed

• A relatively uncommon FaultError in bt() was fixed
• Fixed some address computation bugs for exported module symbols
• Lots of documentation and testing improvements!

0.1.0 - Tue, Mar 14, 2023

• Improvements to the CLI:
  • Debuginfo extraction support is now here! When the /share/linuxrpm directory exists, the DRGN CLI will automatically extract the vmlinux in the case where it is not found.
  • Module debuginfo extraction support! You can ask drgn-tools to load an individual module's debuginfo, and optionally extract it when necessary: KernelModule.load_debuginfo(extract=True). You can also ask to load a list of module debuginfo, or all debuginfo, with drgn_tools.module.load_module_debuginfo(). Finally, you can have the DRGN CLI automatically load all module debuginfo with DRGN -x.
  • dmesg(prog) will open the kernel log in a pager for easy reading.
  • The CLI contains a few more commonly used helpers from drgn_tools
• The drgn.helpers.linux.idr module has been patched to include support for UEK4. This patch (by Imran) is already integrated in drgn main branch, but has not been released and won't see release there for a while. So it's included in drgn_tools. In order for the "patch" to apply, you need to import drgn_tools -- even if you're not using it.
• Symbol loading for modules without DWARF debuginfo was further improved: now, module symbols can be found using the exported symbol and GPL symbol list on the struct module *. This information is combined with module kallsyms to provide a decent baseline level of support even for modules without debuginfo. The only area where this would be less helpful is for purposely obfuscated modules, e.g. antivirus. It's quite helpful for giving you better backtrace information.
• Added NVMe helpers by Ritika.
• Added In-Flight I/O helpers by Junxiao.
• Added Workqueue helpers by Imran.
• Improvements to the CI testing:
  • Each OL and UEK version now shows up under its own collapsible sub-header in the CI testing output. This makes it easier to scan the output and find what you're interested in.
  • Fixed a flaky block test by retrying it, so test results should be more reliable now.

0.0.7 - Tue, Feb 14, 2023

• Really fixed the version string

0.0.6 - Tue, Feb 14, 2023

• Fixed the version string
• Fixed missing newline in cli header

0.0.5 - Tue, Feb 14, 2023

• Minor improvements to module symbol table lookup and backtrace printing.
• Minor improvements to CLI code to support unreleased drgn changes.
• Add redirect_stdout()

0.0.4 - Fri, Jan 13, 2023

Some major improvements to the backtrace helper:

• Use bt(prog, cpu=5) as a shortcut for backtracing the active task.
• Get rid of the return value unless requested.
• Lookup symbols in the module symbol table even without debuginfo.

Updated the kernel module helper and added the ability to lookup symbols.

Added a CLI wrapper which can automatically locate the vmlinux: DRGN.

0.0.3 - Mon, Jan 9, 2023

Adds the backtrace helper.

0.0.2 - Mon, Jan 9, 2023

This the first release for internal distribution, with more helpers.

Contains additional helpers:

• virtio
• kernel module helpers
• logging

0.0.1 - Mon, Jul 25, 2022

• Initial release, containing one helper and some documentation.