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,URIBL_BLOCKED, USER_AGENT_GIT 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 92C49C43387 for ; Wed, 9 Jan 2019 11:49:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 616772173B for ; Wed, 9 Jan 2019 11:49:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731046AbfAILsl (ORCPT ); Wed, 9 Jan 2019 06:48:41 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:56146 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730960AbfAILsd (ORCPT ); Wed, 9 Jan 2019 06:48:33 -0500 Received: from localhost ([127.0.0.1] helo=bazinga.breakpoint.cc) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1ghCLU-0007Al-Md; Wed, 09 Jan 2019 12:48:28 +0100 From: Sebastian Andrzej Siewior To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, Andy Lutomirski , Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , kvm@vger.kernel.org, "Jason A. Donenfeld" , Rik van Riel , Dave Hansen , Sebastian Andrzej Siewior Subject: [PATCH 06/22] x86/fpu: Don't save fxregs for ia32 frames in copy_fpstate_to_sigframe() Date: Wed, 9 Jan 2019 12:47:28 +0100 Message-Id: <20190109114744.10936-7-bigeasy@linutronix.de> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190109114744.10936-1-bigeasy@linutronix.de> References: <20190109114744.10936-1-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Why does copy_fpstate_to_sigframe() do copy_fxregs_to_kernel() in the ia32_fxstate case? I don't know. It just does. Maybe it was required at some point, maybe it was added by accident and nobody noticed it because it makes no difference. In copy_fpstate_to_sigframe() we stash the FPU state into the task's stackframe. Then the CPU's FPU registers (and its fpu->state) are cleared (handle_signal() does fpu__clear()). So it makes *no* difference what happens to fpu->state after copy_fpregs_to_sigframe(). Remove copy_fxregs_to_kernel() since it does not matter what it does and save a few cycles. Signed-off-by: Sebastian Andrzej Siewior --- arch/x86/kernel/fpu/signal.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index c136a4327659d..047390a45e016 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -174,9 +174,6 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) /* Save the live register state to the user directly. */ if (copy_fpregs_to_sigframe(buf_fx)) return -1; - /* Update the thread's fxstate to save the fsave header. */ - if (ia32_fxstate) - copy_fxregs_to_kernel(fpu); /* Save the fsave header for the 32-bit frames. */ if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf)) -- 2.20.1