From 262fa734a0023a43391f9bd4a4099487b8393f35 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Tue, 25 Apr 2017 20:48:52 -0500 Subject: [PATCH] x86/unwind: Dump all stacks in unwind_dump() Currently unwind_dump() dumps only the most recently accessed stack. But it has a few issues. In some cases, 'first_sp' can get out of sync with 'stack_info', causing unwind_dump() to start from the wrong address, flood the printk buffer, and eventually read a bad address. In other cases, dumping only the most recently accessed stack doesn't give enough data to diagnose the error. Fix both issues by dumping *all* stacks involved in the trace, not just the last one. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 8b5e99f02264 ("x86/unwind: Dump stack data on warnings") Link: http://lkml.kernel.org/r/016d6a9810d7d1bfc87ef8c0e6ee041c6744c909.1493171120.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/unwind_frame.c | 34 +++++++++++++++++++++------------- 1 file changed, 21 insertions(+), 13 deletions(-) diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c index ae0821f6c3a5..fec70fe3b1ec 100644 --- a/arch/x86/kernel/unwind_frame.c +++ b/arch/x86/kernel/unwind_frame.c @@ -30,6 +30,8 @@ static void unwind_dump(struct unwind_state *state) static bool dumped_before = false; bool prev_zero, zero = false; unsigned long word, *sp; + struct stack_info stack_info = {0}; + unsigned long visit_mask = 0; if (dumped_before) return; @@ -40,21 +42,27 @@ 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 < state->stack_info.end; sp++) { - word = READ_ONCE_NOCHECK(*sp); + for (sp = state->orig_sp; sp; sp = PTR_ALIGN(stack_info.next_sp, sizeof(long))) { + if (get_stack_info(sp, state->task, &stack_info, &visit_mask)) + break; - prev_zero = zero; - zero = word == 0; + for (; sp < stack_info.end; sp++) { - if (zero) { - if (!prev_zero) - printk_deferred("%p: %0*x ...\n", - sp, BITS_PER_LONG/4, 0); - continue; - } + word = READ_ONCE_NOCHECK(*sp); + + prev_zero = zero; + zero = word == 0; - printk_deferred("%p: %0*lx (%pB)\n", - sp, BITS_PER_LONG/4, word, (void *)word); + if (zero) { + if (!prev_zero) + printk_deferred("%p: %0*x ...\n", + sp, BITS_PER_LONG/4, 0); + continue; + } + + printk_deferred("%p: %0*lx (%pB)\n", + sp, BITS_PER_LONG/4, word, (void *)word); + } } } @@ -216,7 +224,7 @@ static bool update_stack_state(struct unwind_state *state, } /* Save the original stack pointer for unwind_dump(): */ - if (!state->orig_sp || info->type != prev_type) + if (!state->orig_sp) state->orig_sp = frame; return true; -- 2.30.2