From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 70D2DC43219 for ; Tue, 30 Apr 2019 08:31:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3A6B72080C for ; Tue, 30 Apr 2019 08:31:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726719AbfD3Ibg (ORCPT ); Tue, 30 Apr 2019 04:31:36 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:45787 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725769AbfD3Ibf (ORCPT ); Tue, 30 Apr 2019 04:31:35 -0400 Received: from bigeasy by Galois.linutronix.de with local (Exim 4.80) (envelope-from ) id 1hLOAg-0007ho-Kj; Tue, 30 Apr 2019 10:31:26 +0200 Date: Tue, 30 Apr 2019 10:31:26 +0200 From: Sebastian Andrzej Siewior To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, jannh@google.com, riel@surriel.com, mingo@redhat.com, bp@suse.de, Jason@zx2c4.com, luto@kernel.org, tglx@linutronix.de, rkrcmar@redhat.com, mingo@kernel.org, hpa@zytor.com, kvm@vger.kernel.org, pbonzini@redhat.com, kurt.kanzenbach@linutronix.de, Dave Hansen Subject: [PATCH] x86/fpu: Remove unneeded saving of FPU registers in copy_fpstate_to_sigframe() Message-ID: <20190430083126.rilbb76yc27vrem5@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since commit eeec00d73be2e ("x86/fpu: Fault-in user stack if copy_fpstate_to_sigframe() fails") there is no need to have FPU registers saved if copy_fpregs_to_sigframe() fails because we retry it after we resolved the fault condition. Saving the registers is not wrong but it is not needed and it forces us to load the FPU registers on the retry attempt. Don't save the FPU registers if copy_fpstate_to_sigframe() fails. Signed-off-by: Sebastian Andrzej Siewior --- arch/x86/kernel/fpu/signal.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 9834ff8b570b7..eaddb185cac95 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -134,10 +134,9 @@ static inline int copy_fpregs_to_sigframe(struct xregs_state __user *buf) */ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) { - struct fpu *fpu = ¤t->thread.fpu; struct task_struct *tsk = current; int ia32_fxstate = (buf != buf_fx); - int ret = -EFAULT; + int ret; ia32_fxstate &= (IS_ENABLED(CONFIG_X86_32) || IS_ENABLED(CONFIG_IA32_EMULATION)); @@ -164,9 +163,6 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) pagefault_disable(); ret = copy_fpregs_to_sigframe(buf_fx); pagefault_enable(); - if (ret && !test_thread_flag(TIF_NEED_FPU_LOAD)) - copy_fpregs_to_fpstate(fpu); - set_thread_flag(TIF_NEED_FPU_LOAD); fpregs_unlock(); if (ret) { -- 2.20.1