From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754831AbbBFUCP (ORCPT ); Fri, 6 Feb 2015 15:02:15 -0500 Received: from shelob.surriel.com ([74.92.59.67]:43972 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752752AbbBFUCO (ORCPT ); Fri, 6 Feb 2015 15:02:14 -0500 From: riel@redhat.com To: oleg@redhat.com Cc: dave.hansen@linux.intel.com, sbsiddha@gmail.com, luto@amacapital.net, tglx@linutronix.de, mingo@kernel.org, hpa@zytor.com, fenghua.yu@intel.com, x86@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 3/8] x86, fpu: kill save_init_fpu(), change math_error() to use unlazy_fpu() Date: Fri, 6 Feb 2015 15:02:00 -0500 Message-Id: <1423252925-14451-4-git-send-email-riel@redhat.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1423252925-14451-1-git-send-email-riel@redhat.com> References: <1423252925-14451-1-git-send-email-riel@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Oleg Nesterov math_error() calls save_init_fpu() after conditional_sti(), this means that the caller can be preempted. If !use_eager_fpu() we can hit the WARN_ON_ONCE(!__thread_has_fpu(tsk)) and/or save the wrong FPU state. Change math_error() to use unlazy_fpu() and kill save_init_fpu(). Signed-off-by: Oleg Nesterov Signed-off-by: Rik van Riel --- arch/x86/include/asm/fpu-internal.h | 18 ------------------ arch/x86/kernel/traps.c | 2 +- 2 files changed, 1 insertion(+), 19 deletions(-) diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h index 0dbc08282291..27d00e04f911 100644 --- a/arch/x86/include/asm/fpu-internal.h +++ b/arch/x86/include/asm/fpu-internal.h @@ -520,24 +520,6 @@ static inline void __save_fpu(struct task_struct *tsk) } /* - * These disable preemption on their own and are safe - */ -static inline void save_init_fpu(struct task_struct *tsk) -{ - WARN_ON_ONCE(!__thread_has_fpu(tsk)); - - if (use_eager_fpu()) { - __save_fpu(tsk); - return; - } - - preempt_disable(); - __save_init_fpu(tsk); - __thread_fpu_end(tsk); - preempt_enable(); -} - -/* * i387 state interaction */ static inline unsigned short get_fpu_cwd(struct task_struct *tsk) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index fb4cb6adf225..51c465846f06 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -663,7 +663,7 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr) /* * Save the info for the exception handler and clear the error. */ - save_init_fpu(task); + unlazy_fpu(task); task->thread.trap_nr = trapnr; task->thread.error_code = error_code; info.si_signo = SIGFPE; -- 1.9.3