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x86/unwind: Dump all stacks in unwind_dump()

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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 <jpoimboe@redhat.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 8b5e99f022 ("x86/unwind: Dump stack data on warnings")
Link: http://lkml.kernel.org/r/016d6a9810d7d1bfc87ef8c0e6ee041c6744c909.1493171120.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Josh Poimboeuf 2017-04-25 20:48:52 -05:00 committed by Ingo Molnar
parent b0d50c7b5d
commit 262fa734a0
1 changed files with 21 additions and 13 deletions
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34
arch/x86/kernel/unwind_frame.c
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@ -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;
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);
}
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;