Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263019AbTEGJVE (ORCPT ); Wed, 7 May 2003 05:21:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263020AbTEGJVE (ORCPT ); Wed, 7 May 2003 05:21:04 -0400 Received: from meryl.it.uu.se ([130.238.12.42]:2538 "EHLO meryl.it.uu.se") by vger.kernel.org with ESMTP id S263019AbTEGJVC (ORCPT ); Wed, 7 May 2003 05:21:02 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16056.53993.774345.897852@gargle.gargle.HOWL> Date: Wed, 7 May 2003 11:33:29 +0200 From: mikpe@csd.uu.se To: Dave Jones Cc: torvalds@transmeta.com, linux-kernel@vger.kernel.org Subject: [PATCH] restore sysenter MSRs at resume In-Reply-To: <20030506223534.GA3339@suse.de> References: <16056.4728.649612.413159@gargle.gargle.HOWL> <20030506223534.GA3339@suse.de> X-Mailer: VM 6.90 under Emacs 20.7.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3199 Lines: 101 Dave Jones writes: > On Tue, May 06, 2003 at 09:52:24PM +0200, mikpe@csd.uu.se wrote: > > suspending the box (apm). At resume, I am immediately greeted with an > > oops looking like: > > > > general protection fault: 0000 [#?] > > CPU: 0 > > EIP: 0060:[] Not tainted > > EFLAGS: 00010246 > > EIP is at systenter_past_esp+0x6e/0x71 > > I wonder if your BIOS is trashing the sysenter MSRs on suspend. > Maybe they need restoring ? I've confirmed that that's exatly what's happening. EIP points to the sysexit instruction in entry.S, and the sysenter MSRs are all zero. The patch below hooks sysenter into the driver model and implements a resume() method which restores the sysenter MSRs. On my '98 vintage Latitude, this is necessary since those MSRs are cleared at resume. Failure to restore them leads to oopses and eventual kernel hang. (Of course, your user-space must also use sysenter. RH9 does.) The patch has a debug printk() for problematic systems that require the fix. If it says your machine didn't preserve the MSRs, please post a note about this to LKML with your machine model, so we can estimate the scope of the problem. /Mikael diff -ruN linux-2.5.69/arch/i386/kernel/sysenter.c linux-2.5.69.sysenter-pm/arch/i386/kernel/sysenter.c --- linux-2.5.69/arch/i386/kernel/sysenter.c 2003-05-05 22:56:28.000000000 +0200 +++ linux-2.5.69.sysenter-pm/arch/i386/kernel/sysenter.c 2003-05-07 10:50:39.690468848 +0200 @@ -51,6 +51,53 @@ put_cpu(); } +#ifdef CONFIG_PM +#include + +static int sysenter_resume(struct device *dev, u32 state, u32 level) +{ + if (level != RESUME_POWER_ON) + return 0; + /* for collecting statistics, will go away */ + { + unsigned int h, l0, l1, l2; + rdmsr(MSR_IA32_SYSENTER_CS, l0, h); + rdmsr(MSR_IA32_SYSENTER_ESP, l1, h); + rdmsr(MSR_IA32_SYSENTER_EIP, l2, h); + if (!l0 || !l1 || !l2) + printk("sysenter_resume: your BIOS didn't preserve the SYSENTER MSRs\n"); + else + printk("sysenter_resume: congratulations, your BIOS seems Ok\n"); + } + enable_sep_cpu(NULL); + return 0; +} + +static struct device_driver sysenter_driver = { + .name = "sysenter", + .bus = &system_bus_type, + .resume = sysenter_resume, +}; + +static struct sys_device device_sysenter = { + .name = "sysenter", + .id = 0, + .dev = { + .name = "sysenter", + .driver = &sysenter_driver, + }, +}; + +static int __init init_sysenter_devicefs(void) +{ + driver_register(&sysenter_driver); + return sys_device_register(&device_sysenter); +} + +#else /* CONFIG_PM */ +static inline int init_sysenter_devicefs(void) { return 0; } +#endif /* CONFIG_PM */ + /* * These symbols are defined by vsyscall.o to mark the bounds * of the ELF DSO images included therein. @@ -76,7 +123,7 @@ &vsyscall_sysenter_end - &vsyscall_sysenter_start); on_each_cpu(enable_sep_cpu, NULL, 1, 1); - return 0; + return init_sysenter_devicefs(); } __initcall(sysenter_setup); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/