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=-5.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 F3E78C282D7 for ; Wed, 30 Jan 2019 11:43:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C331220882 for ; Wed, 30 Jan 2019 11:43:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="lyC7/EIw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730795AbfA3Ln2 (ORCPT ); Wed, 30 Jan 2019 06:43:28 -0500 Received: from mail.skyhub.de ([5.9.137.197]:59820 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730680AbfA3Ln1 (ORCPT ); Wed, 30 Jan 2019 06:43:27 -0500 Received: from zn.tnic (p200300EC2BCAED00302FA729E39312A6.dip0.t-ipconnect.de [IPv6:2003:ec:2bca:ed00:302f:a729:e393:12a6]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 815DE1EC0338; Wed, 30 Jan 2019 12:43:25 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1548848605; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6dIWZsK/S1Dcdfk00N8urUtaJYC5S5Df1g37fOPLXBo=; b=lyC7/EIw71YTNK/MDB15plI8Ft0OrwuiRn8nCxEYBxA7SoFs60Nj0JaGN47bhkxWWza932 V5yD95lCU5oVctDhI7yB9wa9dC2XWdIU8Snlj4bdvaaQfiuCCZA61eq/Hueu3Y8Di27ZZ/ /rrmg8d0XvdCOyIeo6biudNUS1HpTVg= Date: Wed, 30 Jan 2019 12:43:22 +0100 From: Borislav Petkov To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, x86@kernel.org, Andy Lutomirski , Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , kvm@vger.kernel.org, "Jason A. Donenfeld" , Rik van Riel , Dave Hansen Subject: Re: [PATCH 16/22] x86/fpu: Always store the registers in copy_fpstate_to_sigframe() Message-ID: <20190130114322.GD18383@zn.tnic> References: <20190109114744.10936-1-bigeasy@linutronix.de> <20190109114744.10936-17-bigeasy@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20190109114744.10936-17-bigeasy@linutronix.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 09, 2019 at 12:47:38PM +0100, Sebastian Andrzej Siewior wrote: > From: Rik van Riel > > copy_fpstate_to_sigframe() stores the registers directly to user space. > This is okay because the FPU register are valid and saving it directly > avoids saving it into kernel memory and making a copy. > However… We can't keep doing this if we are going to restore the FPU > registers on the return to userland. It is possible that the FPU > registers will be invalidated in the middle of the save operation and > this should be done with disabled preemption / BH. > > Save the FPU registers to task's FPU struct and copy them to the user > memory later on. > > This code is extracted from an earlier version of the patchset while > there still was lazy-FPU on x86. > > Signed-off-by: Rik van Riel > Signed-off-by: Sebastian Andrzej Siewior > --- > arch/x86/include/asm/fpu/internal.h | 45 ----------------------------- > arch/x86/kernel/fpu/signal.c | 29 +++++++------------ > 2 files changed, 10 insertions(+), 64 deletions(-) ... > @@ -171,9 +156,15 @@ int copy_fpstate_to_sigframe(void __user *buf, void __user *buf_fx, int size) > sizeof(struct user_i387_ia32_struct), NULL, > (struct _fpstate_32 __user *) buf) ? -1 : 1; > > - /* Save the live register state to the user directly. */ > - if (copy_fpregs_to_sigframe(buf_fx)) > - return -1; > + copy_fpregs_to_fpstate(fpu); > + > + if (using_compacted_format()) { > + copy_xstate_to_user(buf_fx, xsave, 0, size); > + } else { > + fpstate_sanitize_xstate(fpu); > + if (__copy_to_user(buf_fx, xsave, fpu_user_xstate_size)) > + return -1; > + } > > /* Save the fsave header for the 32-bit frames. */ > if ((ia32_fxstate || !use_fxsr()) && save_fsave_header(tsk, buf)) Comments above that function need updating. -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.