mirror of
https://github.com/torvalds/linux.git
synced 2026-07-30 19:21:28 +02:00
Linux kernel source tree
77acd1cd91
[Why]
The behavior of drm_atomic_helper_cleanup_planes differs depending on
whether the commit was asynchronous or not. When it's called from
amdgpu_dm_atomic_commit_tail during a typical atomic commit the
plane state has been swapped so it calls cleanup_fb on the old plane
state.
However, in the asynchronous commit codepath the call to
drm_atomic_helper_commit also calls dm_plane_helper_cleanup_fb after
atomic_async_update has been called. Since the plane state is updated
in place and has not been swapped the cleanup_fb call affects the new
plane state.
This results in a use after free for the given sequence:
- Fast update, fb1 pin/ref, fb1 unpin/unref
- Fast update, fb2 pin/ref, fb2 unpin/unref
- Slow update, fb1 pin/ref, fb2 unpin/unref
- Fast update, fb2 pin/ref -> use after free. bug
[How]
Disallow framebuffer changes in the fast path. Since this includes
a NULL framebuffer, this means that only framebuffers that have
been previously pin+ref at least once will be used, preventing a
use after free.
This has a significant throughput reduction for cursor updates where
the framebuffer changes. For most desktop usage this isn't a problem,
but it does introduce performance regressions for two specific IGT
tests:
- cursor-vs-flip-toggle
- cursor-vs-flip-varying-size
Fixes: 2cc751931afc ("drm/amd/display: Add fast path for cursor plane updates")
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.