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, 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 099E5C432C0 for ; Fri, 22 Nov 2019 20:32:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C945520708 for ; Fri, 22 Nov 2019 20:32:21 +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="m+N+WXsh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727196AbfKVUcU (ORCPT ); Fri, 22 Nov 2019 15:32:20 -0500 Received: from merlin.infradead.org ([205.233.59.134]:43604 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726089AbfKVUcU (ORCPT ); Fri, 22 Nov 2019 15:32:20 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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=+Yg2/Hm5cj1++a0Hcu01FV0/uqXnkXadO3bz6Dd3Kiw=; b=m+N+WXshWpx+s7Wc8ziZvesKW tEdUpEx+9YOIXbTLZTQ+Y3YEBkxaTGqap4wjjb09MBT4LHGRJi/kv464oRqzU17dHHcLjaqZss/Xs hoJqbQiE4Yfpoh5D3s8qPLQp3H9wfJFcHOIGYYhr/wtHsJKwlAN1uJoOJFJHLinY53jQ3nKKDaQKE STjwD14ik9HuyPF76d+KL6im0oskgRNVmmeFO0yMsnIZGpXTMTDeO0SG4FtIlkts+ebz0BjsLhAIy EgBHpdLh2QPBkesPGS7wpWS1SCaAq/3KgsXCHN+ELZKmJw8FlBcNGELBuxS7Yj6Hc091HnCYq7uAX cSM0A4sSg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iYFbD-0006Gv-82; Fri, 22 Nov 2019 20:32:15 +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 90362300565; Fri, 22 Nov 2019 21:31:02 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 0BC2F20321DB0; Fri, 22 Nov 2019 21:32:14 +0100 (CET) Date: Fri, 22 Nov 2019 21:32:14 +0100 From: Peter Zijlstra To: David Laight Cc: 'Andy Lutomirski' , Ingo Molnar , Fenghua Yu , 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: <20191122203213.GF2844@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> <397239502dad4bc3819c49c7d569c70c@AcuMS.aculab.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <397239502dad4bc3819c49c7d569c70c@AcuMS.aculab.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 Fri, Nov 22, 2019 at 09:46:16AM +0000, David Laight wrote: > From Andy Lutomirski > > Can we really not just change the lock asm to use 32-bit accesses for > > set_bit(), etc? Sure, it will fail if the bit index is greater than > > 2^32, but that seems nuts. > > For little endian 64bit cpu it is safe(ish) to cast int [] to long [] for the bitops. But that generates the alignment issues this patch set is concerned about.