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02586692ac
[ Upstream commit 57e2428f8df8263275344566e02c277648a4b7f1 ]
PUSH_REGS with save_ret=1 is used by interrupt entry helper functions that
initially start with a UNWIND_HINT_FUNC ORC state.
However, save_ret=1 means that we clobber the helper function's return
address (and then later restore the return address further down on the
stack); after that point, the only thing on the stack we can unwind through
is the IRET frame, so use UNWIND_HINT_IRET_REGS until we have a full
pt_regs frame.
( An alternate approach would be to move the pt_regs->di overwrite down
such that it is the final step of pt_regs setup; but I don't want to
rearrange entry code just to make unwinding a tiny bit more elegant. )
Fixes: 9e809d15d6 ("x86/entry: Reduce the code footprint of the 'idtentry' macro")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20250325-2025-03-unwind-fixes-v1-1-acd774364768@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
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.