diff options
| author | Jann Horn <jannh@google.com> | 2025-03-25 03:01:22 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-03-25 08:30:43 +0100 |
| commit | 57e2428f8df8263275344566e02c277648a4b7f1 (patch) | |
| tree | 2c04d02c359f4fd51b07523e4a5e501dc0fafd48 | |
| parent | 2704ad556cf2b1f3a08526f4f12f9200cf7dcb03 (diff) | |
x86/entry: Fix ORC unwinder for PUSH_REGS with save_ret=1
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: 9e809d15d6b6 ("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
| -rw-r--r-- | arch/x86/entry/calling.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/entry/calling.h b/arch/x86/entry/calling.h index cb0911c5dc5d..d83236b96f22 100644 --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -70,6 +70,8 @@ For 32-bit we have the following conventions - kernel is built with pushq %rsi /* pt_regs->si */ movq 8(%rsp), %rsi /* temporarily store the return address in %rsi */ movq %rdi, 8(%rsp) /* pt_regs->di (overwriting original return address) */ + /* We just clobbered the return address - use the IRET frame for unwinding: */ + UNWIND_HINT_IRET_REGS offset=3*8 .else pushq %rdi /* pt_regs->di */ pushq %rsi /* pt_regs->si */ |