From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753926AbdKXRY7 (ORCPT ); Fri, 24 Nov 2017 12:24:59 -0500 Received: from mail-wm0-f67.google.com ([74.125.82.67]:45289 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753565AbdKXRYx (ORCPT ); Fri, 24 Nov 2017 12:24:53 -0500 X-Google-Smtp-Source: AGs4zMZiR3a9GX2s22e1jtlWwUR6DAKM4xd7tyFthdWXwOURpDyuBtEXjmOTSUVJ4Ox04bzmZhhUMQ== From: Ingo Molnar To: linux-kernel@vger.kernel.org Cc: Dave Hansen , Andy Lutomirski , Thomas Gleixner , "H . Peter Anvin" , Peter Zijlstra , Borislav Petkov , Linus Torvalds Subject: [PATCH 08/43] x86/dumpstack: Handle stack overflow on all stacks Date: Fri, 24 Nov 2017 18:23:36 +0100 Message-Id: <20171124172411.19476-9-mingo@kernel.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171124172411.19476-1-mingo@kernel.org> References: <20171124172411.19476-1-mingo@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Lutomirski 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 Signed-off-by: Thomas Gleixner Reviewed-by: Borislav Petkov Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Link: https://lkml.kernel.org/r/5454bb325cb30a70457a47b50f22317be65eba7d.1511497875.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/dumpstack.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 5e7d10e8ca25..a8aa70c05489 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -90,24 +90,28 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, * - 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) -- 2.14.1