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 EC37EC43143 for ; Thu, 21 Jun 2018 20:37:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E37E21ADE for ; Thu, 21 Jun 2018 20:37:05 +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="PLdSb5Sf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8E37E21ADE 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 S933191AbeFUUhD (ORCPT ); Thu, 21 Jun 2018 16:37:03 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:44484 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932721AbeFUUhC (ORCPT ); Thu, 21 Jun 2018 16:37:02 -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=sGhY4WTm00CET9wC8aqetxlub3+aTf80pa+yUUBsLK0=; b=PLdSb5SfWQt4/fOWwB7NX0XJt PJJqSZAVVRnKs5eAkE/a41GnI2SPa60IdaPprHaMp848BZ6DmtsqGwSKD6AWnvbA720rTSaomYxjx N5Bcb4ZVvgNv4rFznqmQAqrAvkS4av2A/alOlH9WEPhirnyW3sY2gXYKU57X0YUxhNNJZRffJusXL DOe2NCBpvsroQfXDNhyOrAz2yaQ4wxk6YLupB5hvzLPeiSQgT9oRVi8i7w8mZoLK5yn/M9rkZgOwX Dw9817nqlpFSga49TfGIWuzVdQpGlylJuKdbpamitXwpOtx1ebfSgPMXU2HMKhqs4PvFGQgohQEHp AQGL9/whg==; 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 1fW6KA-0004Ud-DY; Thu, 21 Jun 2018 20:36:58 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D854F2029FA0E; Thu, 21 Jun 2018 22:36:56 +0200 (CEST) Date: Thu, 21 Jun 2018 22:36:56 +0200 From: Peter Zijlstra To: Fenghua Yu Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Ashok Raj , Dave Hansen , Rafael Wysocki , Tony Luck , Alan Cox , Ravi V Shankar , Arjan van de Ven , linux-kernel , x86 Subject: Re: [RFC PATCH 00/16] x86/split_lock: Enable #AC exception for split locked accesses Message-ID: <20180621203656.GF27616@hirez.programming.kicks-ass.net> References: <1527435965-202085-1-git-send-email-fenghua.yu@intel.com> <20180621193738.GA13636@worktop.programming.kicks-ass.net> <20180621201851.GC114883@romley-ivt3.sc.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180621201851.GC114883@romley-ivt3.sc.intel.com> 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 Thu, Jun 21, 2018 at 01:18:52PM -0700, Fenghua Yu wrote: > On Thu, Jun 21, 2018 at 09:37:38PM +0200, Peter Zijlstra wrote: > > On Sun, May 27, 2018 at 08:45:49AM -0700, Fenghua Yu wrote: > > > Currently we can trace split lock event counter for debug purpose. But > > > > How? A while ago I actually tried that, but I could not find a suitable > > perf event. > > The event name is called sq_misc.split_lock. It's been supported in perf > already. Thanks. > > > Intel introduces mechanism to detect split lock via alignment > > > check exception in Tremont and other future processors. If split lock is > > > from user process, #AC handler can kill the process or re-execute faulting > > > instruction depending on configuration. > > > > Ideally it would #AC any unaligned (implied) LOCK prefix instruction, > > not just across lines. > > This feature only triggers #AC for unaligned cache line access, not for > other aligned (4 bytes, 8 bytes, etc). This is not explicitly said in > ISE. I can add this info in next version of patches. It was clear; what I'm saying it I'd like #AC to happen for any actual unaligned LOCK access, not just across lines.