From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756023Ab2K3WLG (ORCPT ); Fri, 30 Nov 2012 17:11:06 -0500 Received: from terminus.zytor.com ([198.137.202.10]:38349 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751036Ab2K3WLD (ORCPT ); Fri, 30 Nov 2012 17:11:03 -0500 Date: Fri, 30 Nov 2012 14:10:37 -0800 From: tip-bot for Vincent Palatin Message-ID: Cc: linux-kernel@vger.kernel.org, hpa@zytor.com, mingo@kernel.org, olofj@chromium.org, dlaurie@chromium.org, vpalatin@chromium.org, tglx@linutronix.de, hpa@linux.intel.com Reply-To: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, olofj@chromium.org, vpalatin@chromium.org, dlaurie@chromium.org, tglx@linutronix.de, hpa@linux.intel.com In-Reply-To: <1354306532-1014-1-git-send-email-vpalatin@chromium.org> References: <1354306532-1014-1-git-send-email-vpalatin@chromium.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86, fpu: Avoid FPU lazy restore after suspend Git-Commit-ID: 644c154186386bb1fa6446bc5e037b9ed098db46 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 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (terminus.zytor.com [127.0.0.1]); Fri, 30 Nov 2012 14:10:43 -0800 (PST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 644c154186386bb1fa6446bc5e037b9ed098db46 Gitweb: http://git.kernel.org/tip/644c154186386bb1fa6446bc5e037b9ed098db46 Author: Vincent Palatin AuthorDate: Fri, 30 Nov 2012 12:15:32 -0800 Committer: H. Peter Anvin CommitDate: Fri, 30 Nov 2012 13:48:05 -0800 x86, fpu: Avoid FPU lazy restore after suspend When a cpu enters S3 state, the FPU state is lost. After resuming for S3, if we try to lazy restore the FPU for a process running on the same CPU, this will result in a corrupted FPU context. Ensure that "fpu_owner_task" is properly invalided when (re-)initializing a CPU, so nobody will try to lazy restore a state which doesn't exist in the hardware. Tested with a 64-bit kernel on a 4-core Ivybridge CPU with eagerfpu=off, by doing thousands of suspend/resume cycles with 4 processes doing FPU operations running. Without the patch, a process is killed after a few hundreds cycles by a SIGFPE. Cc: Duncan Laurie Cc: Olof Johansson Cc: v3.4+ # for 3.4 need to replace this_cpu_write by percpu_write Signed-off-by: Vincent Palatin Link: http://lkml.kernel.org/r/1354306532-1014-1-git-send-email-vpalatin@chromium.org Signed-off-by: H. Peter Anvin --- arch/x86/include/asm/fpu-internal.h | 15 +++++++++------ arch/x86/kernel/smpboot.c | 5 +++++ 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h index 831dbb9..41ab26e 100644 --- a/arch/x86/include/asm/fpu-internal.h +++ b/arch/x86/include/asm/fpu-internal.h @@ -399,14 +399,17 @@ static inline void drop_init_fpu(struct task_struct *tsk) typedef struct { int preload; } fpu_switch_t; /* - * FIXME! We could do a totally lazy restore, but we need to - * add a per-cpu "this was the task that last touched the FPU - * on this CPU" variable, and the task needs to have a "I last - * touched the FPU on this CPU" and check them. + * Must be run with preemption disabled: this clears the fpu_owner_task, + * on this CPU. * - * We don't do that yet, so "fpu_lazy_restore()" always returns - * false, but some day.. + * This will disable any lazy FPU state restore of the current FPU state, + * but if the current thread owns the FPU, it will still be saved by. */ +static inline void __cpu_disable_lazy_restore(unsigned int cpu) +{ + per_cpu(fpu_owner_task, cpu) = NULL; +} + static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu) { return new == this_cpu_read_stable(fpu_owner_task) && diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index c80a33b..f3e2ec8 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -68,6 +68,8 @@ #include #include #include +#include +#include #include #include #include @@ -818,6 +820,9 @@ int __cpuinit native_cpu_up(unsigned int cpu, struct task_struct *tidle) per_cpu(cpu_state, cpu) = CPU_UP_PREPARE; + /* the FPU context is blank, nobody can own it */ + __cpu_disable_lazy_restore(cpu); + err = do_boot_cpu(apicid, cpu, tidle); if (err) { pr_debug("do_boot_cpu failed %d\n", err);