From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932901AbcGOMBw (ORCPT ); Fri, 15 Jul 2016 08:01:52 -0400 Received: from terminus.zytor.com ([198.137.202.10]:55814 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932565AbcGOMBu (ORCPT ); Fri, 15 Jul 2016 08:01:50 -0400 Date: Fri, 15 Jul 2016 05:00:56 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: dvlasenk@redhat.com, hpa@zytor.com, mingo@kernel.org, linux-kernel@vger.kernel.org, peterz@infradead.org, luto@kernel.org, bp@alien8.de, torvalds@linux-foundation.org, jpoimboe@redhat.com, tglx@linutronix.de, brgerst@gmail.com Reply-To: torvalds@linux-foundation.org, jpoimboe@redhat.com, tglx@linutronix.de, brgerst@gmail.com, dvlasenk@redhat.com, hpa@zytor.com, mingo@kernel.org, linux-kernel@vger.kernel.org, peterz@infradead.org, luto@kernel.org, bp@alien8.de In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/mm] x86/dumpstack: Try harder to get a call trace on stack overflow Git-Commit-ID: 9a2e9da3e003112399f2863b7b6b911043c01895 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 9a2e9da3e003112399f2863b7b6b911043c01895 Gitweb: http://git.kernel.org/tip/9a2e9da3e003112399f2863b7b6b911043c01895 Author: Andy Lutomirski AuthorDate: Thu, 14 Jul 2016 13:22:52 -0700 Committer: Ingo Molnar CommitDate: Fri, 15 Jul 2016 10:26:26 +0200 x86/dumpstack: Try harder to get a call trace on stack overflow If we overflow the stack, print_context_stack() will abort. Detect this case and rewind back into the valid part of the stack so that we can trace it. Signed-off-by: Andy Lutomirski Reviewed-by: Josh Poimboeuf Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/ee1690eb2715ccc5dc187fde94effa4ca0ccbbcd.1468527351.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/dumpstack.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index ef8017c..cc88e25 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -87,7 +87,7 @@ static inline int valid_stack_ptr(struct task_struct *task, else return 0; } - return p > t && p < t + THREAD_SIZE - size; + return p >= t && p < t + THREAD_SIZE - size; } unsigned long @@ -98,6 +98,14 @@ print_context_stack(struct task_struct *task, { struct stack_frame *frame = (struct stack_frame *)bp; + /* + * If we overflowed the stack into a guard page, jump back to the + * bottom of the usable stack. + */ + if ((unsigned long)task_stack_page(task) - (unsigned long)stack < + PAGE_SIZE) + stack = (unsigned long *)task_stack_page(task); + while (valid_stack_ptr(task, stack, sizeof(*stack), end)) { unsigned long addr;