From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1167814AbcKAHR3 (ORCPT ); Tue, 1 Nov 2016 03:17:29 -0400 Received: from terminus.zytor.com ([198.137.202.10]:45864 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S945789AbcKAHRZ (ORCPT ); Tue, 1 Nov 2016 03:17:25 -0400 Date: Tue, 1 Nov 2016 00:16:19 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: tglx@linutronix.de, jpoimboe@redhat.com, oleg@redhat.com, pbonzini@redhat.com, bp@alien8.de, quentin.casasnovas@oracle.com, rusty@rustcorp.com.au, riel@redhat.com, brgerst@gmail.com, luto@kernel.org, dave.hansen@linux.intel.com, kvm@vger.kernel.org, torvalds@linux-foundation.org, fenghua.yu@intel.com, hpa@zytor.com, mingo@kernel.org, dvlasenk@redhat.com, peterz@infradead.org, linux-kernel@vger.kernel.org Reply-To: mingo@kernel.org, fenghua.yu@intel.com, hpa@zytor.com, torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, peterz@infradead.org, dvlasenk@redhat.com, luto@kernel.org, kvm@vger.kernel.org, dave.hansen@linux.intel.com, rusty@rustcorp.com.au, brgerst@gmail.com, riel@redhat.com, bp@alien8.de, oleg@redhat.com, pbonzini@redhat.com, tglx@linutronix.de, jpoimboe@redhat.com, quentin.casasnovas@oracle.com In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/fpu] x86/fpu: Handle #NM without FPU emulation as an error Git-Commit-ID: bef8b6da95229f780a0a7f63e23124058bfad6d3 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: bef8b6da95229f780a0a7f63e23124058bfad6d3 Gitweb: http://git.kernel.org/tip/bef8b6da95229f780a0a7f63e23124058bfad6d3 Author: Andy Lutomirski AuthorDate: Mon, 31 Oct 2016 15:18:47 -0700 Committer: Ingo Molnar CommitDate: Tue, 1 Nov 2016 07:47:54 +0100 x86/fpu: Handle #NM without FPU emulation as an error Don't use CR0.TS. Make it an error rather than making nonsensical changes to the FPU state. (The cond_local_irq_enable() appears to have been pointless, too.) Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: Denys Vlasenko Cc: Fenghua Yu Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Oleg Nesterov Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Quentin Casasnovas Cc: Rik van Riel Cc: Rusty Russell Cc: Thomas Gleixner Cc: kvm list Link: http://lkml.kernel.org/r/f1ee6bf73ed1025fccaab321ba43d0594245f927.1477951965.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/traps.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index bd4e3d4..bf0c6d0 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -853,6 +853,8 @@ do_spurious_interrupt_bug(struct pt_regs *regs, long error_code) dotraplinkage void do_device_not_available(struct pt_regs *regs, long error_code) { + unsigned long cr0; + RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); #ifdef CONFIG_MATH_EMULATION @@ -866,10 +868,20 @@ do_device_not_available(struct pt_regs *regs, long error_code) return; } #endif - fpu__restore(¤t->thread.fpu); /* interrupts still off */ -#ifdef CONFIG_X86_32 - cond_local_irq_enable(regs); -#endif + + /* This should not happen. */ + cr0 = read_cr0(); + if (WARN(cr0 & X86_CR0_TS, "CR0.TS was set")) { + /* Try to fix it up and carry on. */ + write_cr0(cr0 & ~X86_CR0_TS); + } else { + /* + * Something terrible happened, and we're better off trying + * to kill the task than getting stuck in a never-ending + * loop of #NM faults. + */ + die("unexpected #NM exception", regs, error_code); + } } NOKPROBE_SYMBOL(do_device_not_available);