ORC unwinder can currently skip the first frame even if a user does not
ask for it. If both regs and first_frame parameters of unwind_start()
are set to NULL, state->sp and first_frame are later initialized to the
same value for an inactive task. Given there is "less than or equal to"
comparison used at the end of __unwind_start() for skipping stack frames,
the first frame is always skipped in this case.
Drop the equal part of the comparison and make it equivalent to the
frame pointer unwinder.
Signed-off-by: Miroslav Benes <[email protected]>
---
arch/x86/kernel/unwind_orc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kernel/unwind_orc.c b/arch/x86/kernel/unwind_orc.c
index e9cc182aa97e..8452518cc20a 100644
--- a/arch/x86/kernel/unwind_orc.c
+++ b/arch/x86/kernel/unwind_orc.c
@@ -651,7 +651,7 @@ void __unwind_start(struct unwind_state *state, struct task_struct *task,
/* Otherwise, skip ahead to the user-specified starting frame: */
while (!unwind_done(state) &&
(!on_stack(&state->stack_info, first_frame, sizeof(long)) ||
- state->sp <= (unsigned long)first_frame))
+ state->sp < (unsigned long)first_frame))
unwind_next_frame(state);
return;
--
2.25.1
On Wed, Mar 04, 2020 at 01:32:59PM +0100, Miroslav Benes wrote:
> ORC unwinder can currently skip the first frame even if a user does not
> ask for it. If both regs and first_frame parameters of unwind_start()
> are set to NULL, state->sp and first_frame are later initialized to the
> same value for an inactive task. Given there is "less than or equal to"
> comparison used at the end of __unwind_start() for skipping stack frames,
> the first frame is always skipped in this case.
>
> Drop the equal part of the comparison and make it equivalent to the
> frame pointer unwinder.
>
> Signed-off-by: Miroslav Benes <[email protected]>
Acked-by: Josh Poimboeuf <[email protected]>
--
Josh