From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752489AbdKJJqm (ORCPT ); Fri, 10 Nov 2017 04:46:42 -0500 Received: from terminus.zytor.com ([65.50.211.136]:34905 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751220AbdKJJqk (ORCPT ); Fri, 10 Nov 2017 04:46:40 -0500 Date: Fri, 10 Nov 2017 01:41:01 -0800 From: tip-bot for Alexander Shishkin Message-ID: Cc: arjan@linux.intel.com, linux-kernel@vger.kernel.org, idryomov@gmail.com, mingo@kernel.org, alexander.shishkin@linux.intel.com, hpa@zytor.com, tglx@linutronix.de, torvalds@linux-foundation.org, daniel.thompson@linaro.org, richard.weinberger@gmail.com, peterz@infradead.org, jason.wessel@windriver.com, bp@alien8.de Reply-To: alexander.shishkin@linux.intel.com, hpa@zytor.com, arjan@linux.intel.com, mingo@kernel.org, linux-kernel@vger.kernel.org, idryomov@gmail.com, peterz@infradead.org, richard.weinberger@gmail.com, jason.wessel@windriver.com, bp@alien8.de, daniel.thompson@linaro.org, tglx@linutronix.de, torvalds@linux-foundation.org In-Reply-To: <20170724100428.19173-1-alexander.shishkin@linux.intel.com> References: <20170724100428.19173-1-alexander.shishkin@linux.intel.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86/debug: Handle warnings before the notifier chain, to fix KGDB crash Git-Commit-ID: b8347c2196492f4e1cccde3d92fda1cc2cc7de7e 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: b8347c2196492f4e1cccde3d92fda1cc2cc7de7e Gitweb: https://git.kernel.org/tip/b8347c2196492f4e1cccde3d92fda1cc2cc7de7e Author: Alexander Shishkin AuthorDate: Mon, 24 Jul 2017 13:04:28 +0300 Committer: Ingo Molnar CommitDate: Fri, 10 Nov 2017 08:04:19 +0100 x86/debug: Handle warnings before the notifier chain, to fix KGDB crash Commit: 9a93848fe787 ("x86/debug: Implement __WARN() using UD0") turned warnings into UD0, but the fixup code only runs after the notify_die() chain. This is a problem, in particular, with kgdb, which kicks in as if it was a BUG(). Fix this by running the fixup code before the notifier chain in the invalid op handler path. Signed-off-by: Alexander Shishkin Tested-by: Ilya Dryomov Acked-by: Daniel Thompson Acked-by: Thomas Gleixner Cc: Jason Wessel Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Richard Weinberger Cc: # v4.12+ Link: http://lkml.kernel.org/r/20170724100428.19173-1-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/traps.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 67db4f4..5a6b8f8 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -209,9 +209,6 @@ do_trap_no_signal(struct task_struct *tsk, int trapnr, char *str, if (fixup_exception(regs, trapnr)) return 0; - if (fixup_bug(regs, trapnr)) - return 0; - tsk->thread.error_code = error_code; tsk->thread.trap_nr = trapnr; die(str, regs, error_code); @@ -292,6 +289,13 @@ static void do_error_trap(struct pt_regs *regs, long error_code, char *str, RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); + /* + * WARN*()s end up here; fix them up before we call the + * notifier chain. + */ + if (!user_mode(regs) && fixup_bug(regs, trapnr)) + return; + if (notify_die(DIE_TRAP, str, regs, error_code, trapnr, signr) != NOTIFY_STOP) { cond_local_irq_enable(regs);