diff options
| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2023-03-01 07:13:12 -0800 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-03-23 23:18:58 +0100 |
| commit | fb799447ae2974a07907906dff5bd4b9e47b7123 (patch) | |
| tree | 05f8233eb66094db1be1801c5544776674c5913a /Documentation/livepatch | |
| parent | 4708ea14bef314fc901857eefd65678236a9f2d9 (diff) | |
x86,objtool: Split UNWIND_HINT_EMPTY in two
Mark reported that the ORC unwinder incorrectly marks an unwind as
reliable when the unwind terminates prematurely in the dark corners of
return_to_handler() due to lack of information about the next frame.
The problem is UNWIND_HINT_EMPTY is used in two different situations:
1) The end of the kernel stack unwind before hitting user entry, boot
code, or fork entry
2) A blind spot in ORC coverage where the unwinder has to bail due to
lack of information about the next frame
The ORC unwinder has no way to tell the difference between the two.
When it encounters an undefined stack state with 'end=1', it blindly
marks the stack reliable, which can break the livepatch consistency
model.
Fix it by splitting UNWIND_HINT_EMPTY into UNWIND_HINT_UNDEFINED and
UNWIND_HINT_END_OF_STACK.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/fd6212c8b450d3564b855e1cb48404d6277b4d9f.1677683419.git.jpoimboe@kernel.org
Diffstat (limited to 'Documentation/livepatch')
| -rw-r--r-- | Documentation/livepatch/reliable-stacktrace.rst | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/Documentation/livepatch/reliable-stacktrace.rst b/Documentation/livepatch/reliable-stacktrace.rst index 67459d2ca2af..d56bb706172f 100644 --- a/Documentation/livepatch/reliable-stacktrace.rst +++ b/Documentation/livepatch/reliable-stacktrace.rst @@ -183,7 +183,7 @@ trampoline or return trampoline. For example, considering the x86_64 .. code-block:: none SYM_CODE_START(return_to_handler) - UNWIND_HINT_EMPTY + UNWIND_HINT_UNDEFINED subq $24, %rsp /* Save the return values */ |