From: Miroslav Benes mbenes@suse.cz
commit f1d9a2abff66aa8156fbc1493abed468db63ea48 upstream.
When unwinding an inactive task, the ORC unwinder skips the first frame by default. If both the 'regs' and 'first_frame' parameters of unwind_start() are NULL, 'state->sp' and 'first_frame' are later initialized to the same value for an inactive task. Given there is a "less than or equal to" comparison used at the end of __unwind_start() for skipping stack frames, the first frame is skipped.
Drop the equal part of the comparison and make the behavior equivalent to the frame pointer unwinder.
Fixes: ee9f8fce9964 ("x86/unwind: Add the ORC unwinder") Reviewed-by: Miroslav Benes mbenes@suse.cz Signed-off-by: Miroslav Benes mbenes@suse.cz Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com Signed-off-by: Ingo Molnar mingo@kernel.org Cc: Andy Lutomirski luto@kernel.org Cc: Dave Jones dsj@fb.com Cc: Jann Horn jannh@google.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Vince Weaver vincent.weaver@maine.edu Link: https://lore.kernel.org/r/7f08db872ab59e807016910acdbe82f744de7065.158780874... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/kernel/unwind_orc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/x86/kernel/unwind_orc.c +++ b/arch/x86/kernel/unwind_orc.c @@ -574,7 +574,7 @@ void __unwind_start(struct unwind_state /* 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;