From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:58236 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751261AbdKMJFu (ORCPT ); Mon, 13 Nov 2017 04:05:50 -0500 Subject: Patch "x86/debug: Handle warnings before the notifier chain, to fix KGDB crash" has been added to the 4.13-stable tree To: alexander.shishkin@linux.intel.com, arjan@linux.intel.com, bp@alien8.de, daniel.thompson@linaro.org, gregkh@linuxfoundation.org, idryomov@gmail.com, jason.wessel@windriver.com, mingo@kernel.org, peterz@infradead.org, richard.weinberger@gmail.com, tglx@linutronix.de, torvalds@linux-foundation.org Cc: , From: Date: Mon, 13 Nov 2017 10:05:55 +0100 Message-ID: <1510563955249106@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled x86/debug: Handle warnings before the notifier chain, to fix KGDB crash to the 4.13-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: x86-debug-handle-warnings-before-the-notifier-chain-to-fix-kgdb-crash.patch and it can be found in the queue-4.13 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From b8347c2196492f4e1cccde3d92fda1cc2cc7de7e Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Mon, 24 Jul 2017 13:04:28 +0300 Subject: x86/debug: Handle warnings before the notifier chain, to fix KGDB crash From: Alexander Shishkin commit b8347c2196492f4e1cccde3d92fda1cc2cc7de7e upstream. 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 Link: http://lkml.kernel.org/r/20170724100428.19173-1-alexander.shishkin@linux.intel.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/traps.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -221,9 +221,6 @@ do_trap_no_signal(struct task_struct *ts 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); @@ -304,6 +301,13 @@ static void do_error_trap(struct pt_regs 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); Patches currently in stable-queue which might be from alexander.shishkin@linux.intel.com are queue-4.13/x86-debug-handle-warnings-before-the-notifier-chain-to-fix-kgdb-crash.patch