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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 70EAFC432C0 for ; Thu, 21 Nov 2019 20:25:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4792D20643 for ; Thu, 21 Nov 2019 20:25:22 +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="oFpbapYH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727016AbfKUUZV (ORCPT ); Thu, 21 Nov 2019 15:25:21 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:57118 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726735AbfKUUZS (ORCPT ); Thu, 21 Nov 2019 15:25:18 -0500 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=fm10sCbhB9yLCKNm/DGjjITV1FOI2q8pz+mFa5RmVok=; b=oFpbapYHFIYbuuEJ/9pUoVmvc XOYFazok9WFMYkO1NK/GrdCue1s7HlYm8TVA2h/d5LoEjhbQKGLvOacI5WOVcJpSDWXQzGtxU7yd4 vW6FuMdZuOWsUalYQBivCL+Ek2zJjg3XJn0bF02fCLHQ2FcuvDQ1Meota8kvw1EwpKra7UGleTBaf 2EfDONJpf0dFrJ4OCMW5WZhzxi45SboQJtzuq4A50m24eAY/gnneX7F8G6LaFmKcOxf7Z2GwKT33/ JLurPta4KYP6zuQCfBazE1/Zu7xpgz4N1wrK4H8TI5m6JJPQb4mC3xolP2OGxpkf/0dt0DL1job0L Jov3tX6uA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iXt0o-0004nn-GQ; Thu, 21 Nov 2019 20:25:10 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id B32BB300606; Thu, 21 Nov 2019 21:23:57 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id B10FC201F87D3; Thu, 21 Nov 2019 21:25:08 +0100 (CET) Date: Thu, 21 Nov 2019 21:25:08 +0100 From: Peter Zijlstra To: Fenghua Yu Cc: Andy Lutomirski , David Laight , Ingo Molnar , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Tony Luck , Ashok Raj , Ravi V Shankar , linux-kernel , x86 Subject: Re: [PATCH v10 6/6] x86/split_lock: Enable split lock detection by kernel parameter Message-ID: <20191121202508.GZ4097@hirez.programming.kicks-ass.net> References: <1574297603-198156-1-git-send-email-fenghua.yu@intel.com> <1574297603-198156-7-git-send-email-fenghua.yu@intel.com> <20191121060444.GA55272@gmail.com> <20191121130153.GS4097@hirez.programming.kicks-ass.net> <20191121171214.GD12042@gmail.com> <3481175cbe14457a947f934343946d52@AcuMS.aculab.com> <20191121185303.GB199273@romley-ivt3.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191121185303.GB199273@romley-ivt3.sc.intel.com> 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 Thu, Nov 21, 2019 at 10:53:03AM -0800, Fenghua Yu wrote: > 4. Otherwise, re-calculate addr to point the 32-bit address which contains > the bit and operate on the bit. No split lock. That sounds confused, Even BT{,CRS} have a RmW size. There is no 'operate on the bit'. Specifically I hard rely on BTSL to be a 32bit RmW, see commit: 7aa54be29765 ("locking/qspinlock, x86: Provide liveness guarantee") You might need to read this paper: https://www.cl.cam.ac.uk/~pes20/popl17/mixed-size.pdf