From bf95f6186770fa3f8959e3ea8317ad7db9af1dc3 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Mon, 9 Oct 2017 20:20:04 -0500 Subject: [PATCH] x86/unwind: Align stack pointer in unwinder dump When printing the unwinder dump, the stack pointer could be unaligned, for one of two reasons: - stack corruption; or - GCC created an unaligned stack. There's no way for the unwinder to tell the difference between the two, so we have to assume one or the other. GCC unaligned stacks are very rare, and have only been spotted before GCC 5. Presumably, if we're doing an unwinder stack dump, stack corruption is more likely than a GCC unaligned stack. So always align the stack before starting the dump. Reported-and-tested-by: Tetsuo Handa Reported-and-tested-by: Fengguang Wu Signed-off-by: Josh Poimboeuf Cc: Byungchul Park Cc: LKP Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/2f540c515946ab09ed267e1a1d6421202a0cce08.1507597785.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/unwind_frame.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index 4949bbc95f750..81aca077fbb60 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -44,7 +44,8 @@ static void unwind_dump(struct unwind_state *state) state->stack_info.type, state->stack_info.next_sp, state->stack_mask, state->graph_idx); - for (sp = state->orig_sp; sp; sp = PTR_ALIGN(stack_info.next_sp, sizeof(long))) { + for (sp = PTR_ALIGN(state->orig_sp, sizeof(long)); sp; + sp = PTR_ALIGN(stack_info.next_sp, sizeof(long))) { if (get_stack_info(sp, state->task, &stack_info, &visit_mask)) break; -- 2.39.5