x86/unwind: Dump all stacks in unwind_dump() (262fa734) · Commits · 戴 / test

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: ("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>

arch/x86/kernel/unwind_frame.c

+21 −13

Original line number	Diff line number	Diff line
		@@ -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;
		@@ -40,7 +42,12 @@ 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++) {
		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;

		for (; sp < stack_info.end; sp++) {

		word = READ_ONCE_NOCHECK(*sp);

		prev_zero = zero;
		@@ -57,6 +64,7 @@ static void unwind_dump(struct unwind_state *state)
		sp, BITS_PER_LONG/4, word, (void *)word);
		}
		}
		}

		unsigned long unwind_get_return_address(struct unwind_state *state)
		{
		@@ -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;

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