Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752919AbdFSTcR (ORCPT + 2 others); Mon, 19 Jun 2017 15:32:17 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:51973 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752710AbdFSSey (ORCPT ); Mon, 19 Jun 2017 14:34:54 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Corey Minyard , David Daney , linux-mips@linux-mips.org, Ralf Baechle , Julia Lawall , Jiri Slaby , Willy Tarreau Subject: [PATCH 3.10 256/268] MIPS: Fix crash registers on non-crashing CPUs Date: Mon, 19 Jun 2017 20:32:35 +0200 Message-Id: <1497897167-14556-257-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1497897167-14556-1-git-send-email-w@1wt.eu> References: <1497897167-14556-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Corey Minyard commit c80e1b62ffca52e2d1d865ee58bc79c4c0c55005 upstream. As part of handling a crash on an SMP system, an IPI is send to all other CPUs to save their current registers and stop. It was using task_pt_regs(current) to get the registers, but that will only be accurate if the CPU was interrupted running in userland. Instead allow the architecture to pass in the registers (all pass NULL now, but allow for the future) and then use get_irq_regs() which should be accurate as we are in an interrupt. Fall back to task_pt_regs(current) if nothing else is available. Signed-off-by: Corey Minyard Cc: David Daney Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/13050/ Signed-off-by: Ralf Baechle Cc: Julia Lawall Signed-off-by: Jiri Slaby Signed-off-by: Willy Tarreau --- arch/mips/kernel/crash.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/arch/mips/kernel/crash.c b/arch/mips/kernel/crash.c index 93aa302..c683129 100644 --- a/arch/mips/kernel/crash.c +++ b/arch/mips/kernel/crash.c @@ -15,12 +15,22 @@ static int crashing_cpu = -1; static cpumask_t cpus_in_crash = CPU_MASK_NONE; #ifdef CONFIG_SMP -static void crash_shutdown_secondary(void *ignore) +static void crash_shutdown_secondary(void *passed_regs) { - struct pt_regs *regs; + struct pt_regs *regs = passed_regs; int cpu = smp_processor_id(); - regs = task_pt_regs(current); + /* + * If we are passed registers, use those. Otherwise get the + * regs from the last interrupt, which should be correct, as + * we are in an interrupt. But if the regs are not there, + * pull them from the top of the stack. They are probably + * wrong, but we need something to keep from crashing again. + */ + if (!regs) + regs = get_irq_regs(); + if (!regs) + regs = task_pt_regs(current); if (!cpu_online(cpu)) return; -- 2.8.0.rc2.1.gbe9624a