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=-2.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 C88E0C6778C for ; Tue, 3 Jul 2018 16:41:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 32DFD22437 for ; Tue, 3 Jul 2018 16:41:00 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=firstfloor.org header.i=@firstfloor.org header.b="AxPZ2dNk" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 32DFD22437 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=firstfloor.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934231AbeGCQk4 (ORCPT ); Tue, 3 Jul 2018 12:40:56 -0400 Received: from one.firstfloor.org ([193.170.194.197]:36778 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932759AbeGCQkw (ORCPT ); Tue, 3 Jul 2018 12:40:52 -0400 Received: by one.firstfloor.org (Postfix, from userid 503) id 268EF868EF; Tue, 3 Jul 2018 18:40:49 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=firstfloor.org; s=mail; t=1530636049; bh=5LQr+57Yn86zrNpVPZWygKxAhfwY0IKnbLsc5r5PQVA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AxPZ2dNk9RObD8Mmz7v2Q79DdiZzhlPLZ2fFrm51TyaG2xuq+uqJFK5nbx44p0I++ FpxjJVRAgmExBZNzhXCSfkEo0XjiPcZLrW7gl21qzhphO9/bOQCqsU00kVUB6hHtPt e61x8YPWMjJfNSLGxhRCK5qrVGMU9egN0V5brx8A= Date: Tue, 3 Jul 2018 09:40:48 -0700 From: Andi Kleen To: Peter Zijlstra Cc: Heiko Carstens , Mathieu Desnoyers , Linus Torvalds , Andy Lutomirski , Thomas Gleixner , linux-kernel , linux-api , "Paul E. McKenney" , Boqun Feng , Dave Watson , Paul Turner , Andrew Morton , Russell King , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , Chris Lameter , Ben Maurer , rostedt , Josh Triplett , Catalin Marinas , Will Deacon , Michael Kerrisk , Joel Fernandes , michal.simek@xilinx.com, Martin Schwidefsky , Vasily Gorbik Subject: Re: [RFC PATCH for 4.18] rseq: use __u64 for rseq_cs fields, validate user inputs Message-ID: <20180703164048.i2te5gjemcafqzwf@two.firstfloor.org> References: <8B2E4CEB-3080-4602-8B62-774E400892EB@amacapital.net> <459661281.10865.1530580742205.JavaMail.zimbra@efficios.com> <858886246.10882.1530583291379.JavaMail.zimbra@efficios.com> <1776351430.10902.1530585009519.JavaMail.zimbra@efficios.com> <20180703081449.GT2494@hirez.programming.kicks-ass.net> <20180703082955.GH3704@osiris> <20180703084312.GU2494@hirez.programming.kicks-ass.net> <20180703085546.GJ3704@osiris> <20180703092113.GV2494@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180703092113.GV2494@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > So I think you're good... But yes, you raise an interresting point. So it sounds like architectures that don't have an instruction atomic u64 *_user need to disable interrupts during the access, and somehow handle that case when a page fault happens? -Andi