| Date | Mon, 04 Dec 2017 15:07:18 +0100 | From | Thomas Gleixner <> | Subject | [patch 12/60] x86/dumpstack: Handle stack overflow on all stacks |
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From: Andy Lutomirski <luto@kernel.org>
We currently special-case stack overflow on the task stack. We're going to start putting special stacks in the fixmap with a custom layout, so they'll have guard pages, too. Teach the unwinder to be able to unwind an overflow of any of the stacks.
Signed-off-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Borislav Petkov <bp@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Brian Gerst <brgerst@gmail.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lkml.kernel.org/r/5454bb325cb30a70457a47b50f22317be65eba7d.1511497875.git.luto@kernel.org
--- arch/x86/kernel/dumpstack.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-)
--- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -112,24 +112,28 @@ void show_trace_log_lvl(struct task_stru * - task stack * - interrupt stack * - HW exception stacks (double fault, nmi, debug, mce) + * - SYSENTER stack * - * x86-32 can have up to three stacks: + * x86-32 can have up to four stacks: * - task stack * - softirq stack * - hardirq stack + * - SYSENTER stack */ for (regs = NULL; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) { const char *stack_name; - /* - * If we overflowed the task stack into a guard page, jump back - * to the bottom of the usable stack. - */ - if (task_stack_page(task) - (void *)stack < PAGE_SIZE) - stack = task_stack_page(task); - - if (get_stack_info(stack, task, &stack_info, &visit_mask)) - break; + if (get_stack_info(stack, task, &stack_info, &visit_mask)) { + /* + * We weren't on a valid stack. It's possible that + * we overflowed a valid stack into a guard page. + * See if the next page up is valid so that we can + * generate some kind of backtrace if this happens. + */ + stack = (unsigned long *)PAGE_ALIGN((unsigned long)stack); + if (get_stack_info(stack, task, &stack_info, &visit_mask)) + break; + } stack_name = stack_type_name(stack_info.type); if (stack_name)
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