mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-07 11:26:02 +09:00
41928e303c
To enable RELIABLE_STACKTRACE and LIVEPATCH on arm64, we need to substantially rework arm64's unwinding code. As part of this, we want to minimize the set of unwind interfaces we expose, and avoid open-coding of unwind logic. Currently, dump_backtrace() walks the stack of the current task or a blocked task by calling stact_backtrace() and iterating unwind steps using unwind_frame(). This can be written more simply in terms of arch_stack_walk(), considering three distinct cases: 1) When unwinding a blocked task, start_backtrace() is called with the blocked task's saved PC and FP, and the unwind proceeds immediately from this point without skipping any entries. This is functionally equivalent to calling arch_stack_walk() with the blocked task, which will start with the task's saved PC and FP. There is no functional change to this case. 2) When unwinding the current task without regs, start_backtrace() is called with dump_backtrace() as the PC and __builtin_frame_address(0) as the next frame, and the unwind proceeds immediately without skipping. This is *almost* functionally equivalent to calling arch_stack_walk() for the current task, which will start with its caller (i.e. an offset into dump_backtrace()) as the PC, and the callers frame record as the next frame. The only difference being that dump_backtrace() will be reported with an offset (which is strictly more correct than currently). Otherwise there is no functional cahnge to this case. 3) When unwinding the current task with regs, start_backtrace() is called with dump_backtrace() as the PC and __builtin_frame_address(0) as the next frame, and the unwind is performed silently until the next frame is the frame pointed to by regs->fp. Reporting starts from regs->pc and continues from the frame in regs->fp. Historically, this pre-unwind was necessary to correctly record return addresses rewritten by the ftrace graph calller, but this is no longer necessary as these are now recovered using the FP since commit:c6d3cd32fd("arm64: ftrace: use HAVE_FUNCTION_GRAPH_RET_ADDR_PTR") This pre-unwind is not necessary to recover return addresses rewritten by kretprobes, which historically were not recovered, and are now recovered using the FP since commit:cd9bc2c925("arm64: Recover kretprobe modified return address in stacktrace") Thus, this is functionally equivalent to calling arch_stack_walk() with the current task and regs, which will start with regs->pc as the PC and regs->fp as the next frame, without a pre-unwind. This patch makes dump_backtrace() use arch_stack_walk(). This simplifies dump_backtrace() and will permit subsequent changes to the unwind code. Aside from the improved reporting when unwinding current without regs, there should be no functional change as a result of this patch. Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com> [Mark: elaborate commit message] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Reviewed-by: Mark Brown <broonie@kernel.org> Link: https://lore.kernel.org/r/20211129142849.3056714-9-mark.rutland@arm.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> (cherry picked from commit2dad6dc17b) [willdeacon@: NOTE: We don't havecd9bc2c925and backporting its dependencies is not viable so kretprobe unwinding remains broken even after this patch] Signed-off-by: Will Deacon <willdeacon@google.com> Bug: 233587962 Bug: 233588291 Change-Id: I04ca152601bd64f0e46a606af2aa5b35c86b5bf3
How do I submit patches to Android Common Kernels
-
BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.
- Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux,
additions of
EXPORT_SYMBOL_GPL()require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export. - When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.
- Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux,
additions of
-
LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.
Common Kernel patch requirements
- All patches must conform to the Linux kernel coding standards and pass
scripts/checkpatch.pl - Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
- If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch:
UPSTREAM:,BACKPORT:,FROMGIT:,FROMLIST:, orANDROID:. - All patches must have a
Change-Id:tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html) - If an Android bug has been assigned, there must be a
Bug:tag. - All patches must have a
Signed-off-by:tag by the author and the submitter
Additional requirements are listed below based on patch type
Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:
- If the patch is a cherry-pick from Linux mainline with no changes at all
- tag the patch subject with
UPSTREAM:. - add upstream commit information with a
(cherry picked from commit ...)line - Example:
- if the upstream commit message is
- tag the patch subject with
important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
- then Joe Smith would upload the patch for the common kernel as
UPSTREAM: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
(cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
Signed-off-by: Joe Smith <joe.smith@foo.org>
- If the patch requires any changes from the upstream version, tag the patch with
BACKPORT:instead ofUPSTREAM:.- use the same tags as
UPSTREAM: - add comments about the changes under the
(cherry picked from commit ...)line - Example:
- use the same tags as
BACKPORT: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
(cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
[joe: Resolved minor conflict in drivers/foo/bar.c ]
Signed-off-by: Joe Smith <joe.smith@foo.org>
Requirements for other backports: FROMGIT:, FROMLIST:,
- If the patch has been merged into an upstream maintainer tree, but has not yet
been merged into Linux mainline
- tag the patch subject with
FROMGIT: - add info on where the patch came from as
(cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't uselinux-nextfor example). - if changes were required, use
BACKPORT: FROMGIT: - Example:
- if the commit message in the maintainer tree is
- tag the patch subject with
important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
- then Joe Smith would upload the patch for the common kernel as
FROMGIT: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
(cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Joe Smith <joe.smith@foo.org>
- If the patch has been submitted to LKML, but not accepted into any maintainer tree
- tag the patch subject with
FROMLIST: - add a
Link:tag with a link to the submittal on lore.kernel.org - add a
Bug:tag with the Android bug (required for patches not accepted into a maintainer tree) - if changes were required, use
BACKPORT: FROMLIST: - Example:
- tag the patch subject with
FROMLIST: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Joe Smith <joe.smith@foo.org>
Requirements for Android-specific patches: ANDROID:
- If the patch is fixing a bug to Android-specific code
- tag the patch subject with
ANDROID: - add a
Fixes:tag that cites the patch with the bug - Example:
- tag the patch subject with
ANDROID: fix android-specific bug in foobar.c
This is the detailed description of the important fix
Fixes: 1234abcd2468 ("foobar: add cool feature")
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Joe Smith <joe.smith@foo.org>
- If the patch is a new feature
- tag the patch subject with
ANDROID: - add a
Bug:tag with the Android bug (required for android-specific features)
- tag the patch subject with