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=-2.1 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, 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 72AE9C6778A for ; Tue, 3 Jul 2018 09:25:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D20C24267 for ; Tue, 3 Jul 2018 09:25:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="KsmKFU/o" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2D20C24267 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.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 S933611AbeGCJZM (ORCPT ); Tue, 3 Jul 2018 05:25:12 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:37104 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753973AbeGCJZL (ORCPT ); Tue, 3 Jul 2018 05:25:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=OcRZbgC02JeXu8fjaxbVbSzV+bK1QgZvLnF0LtFPpM4=; b=KsmKFU/oM3OR3qXOJZalwSJ/s ys1uuBr3cvbYxpUpIZvpFLxUOdkABxTZiHGOf/5S1z2OaqzCYqZx7vrR4Nuvuv1ddpeWuyDebeh5f E7VQFMsvVVUvPTcGBhrsnC63JQ/52Sk7cKYeCyRZPnbn+QnJYDdf5VpUjxGlIrLvQeCcqyNY8sxC5 ZCC273v2YHS+deyzKEIdtQhmqOg+0+f/zca3ZyiHLY6MHK/rCzVfdWakq5VPMeaAeTjqh8QLE9Mmx 92PNnSWkyq7cqpTnJ0SbO/mOPVinqjAW6DLPkGQCCViStnzHf8BRhjXZF+0n0m4n2qu4lxYj4FLRD OxRAafi3A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1faHXz-0008J8-SN; Tue, 03 Jul 2018 09:24:32 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id E58F42028932F; Tue, 3 Jul 2018 11:24:29 +0200 (CEST) Date: Tue, 3 Jul 2018 11:24:29 +0200 From: Peter Zijlstra To: Heiko Carstens Cc: 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: <20180703092429.GW2494@hirez.programming.kicks-ass.net> 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> <20180703091717.GK3704@osiris> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180703091717.GK3704@osiris> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 03, 2018 at 11:17:17AM +0200, Heiko Carstens wrote: > And to answer also your question: we don't use a regular load, since we > would have to use 'sacf' construct surrounding the load instruction which > would be much slower. > We have something like that implemented for the futex atomic ops, and we > could also implement something like that for this use case > (e.g. get_user_atomic()), if really needed. /me digs out the s390-PoO PDF and understands.. this is because of the split user/kernel address space stuff. Fair enough.