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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,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 D8495C282C3 for ; Tue, 22 Jan 2019 16:15:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B18D720870 for ; Tue, 22 Jan 2019 16:15:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729085AbfAVQP5 (ORCPT ); Tue, 22 Jan 2019 11:15:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:26998 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728669AbfAVQP5 (ORCPT ); Tue, 22 Jan 2019 11:15:57 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 07CAA58E33; Tue, 22 Jan 2019 16:15:56 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.163]) by smtp.corp.redhat.com (Postfix) with SMTP id 6CA8A5D9C7; Tue, 22 Jan 2019 16:15:52 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 22 Jan 2019 17:15:55 +0100 (CET) Date: Tue, 22 Jan 2019 17:15:51 +0100 From: Oleg Nesterov To: Borislav Petkov Cc: Dave Hansen , Sebastian Andrzej Siewior , Ingo Molnar , 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 05/22] x86/fpu: Remove fpu->initialized usage in copy_fpstate_to_sigframe() Message-ID: <20190122161551.GB9745@redhat.com> References: <20190109114744.10936-1-bigeasy@linutronix.de> <20190109114744.10936-6-bigeasy@linutronix.de> <20190116193603.GK15409@zn.tnic> <20190116224037.xkfnevzkwrck5dtt@linutronix.de> <20190117122253.GC5023@zn.tnic> <20190118211401.4komqsnvuof7563p@linutronix.de> <33f0e144-1eec-b1a1-8858-58f20d5e477d@intel.com> <20190121112117.GA32538@redhat.com> <20190122134015.GI26587@zn.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190122134015.GI26587@zn.tnic> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 22 Jan 2019 16:15:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/22, Borislav Petkov wrote: > > On Mon, Jan 21, 2019 at 12:21:17PM +0100, Oleg Nesterov wrote: > > And in any case I do not understand the idea to use the second > > in-kernel struct fpu. A signal handler can be interrupted by another > > signal, this will need to save/restore the FPU state again. > > Well, we were just speculating whether doing that would simplify the > code around get_sigframe() et al. But if that is an ABI, then we can't > really touch it. > > Btw, where is that whole ABI deal about saving FPU regs on the user > signal stack documented? I don't know... tried to google, found nothing. the comment in /usr/include/sys/ucontext.h mentions SysV/i386 ABI + historical reasons, this didn't help. Oleg.