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 B715EC43141 for ; Thu, 21 Jun 2018 19:37:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7116821CCF for ; Thu, 21 Jun 2018 19:37:54 +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="T6sRmnol" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7116821CCF 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 S932994AbeFUThw (ORCPT ); Thu, 21 Jun 2018 15:37:52 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:45458 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932866AbeFUThv (ORCPT ); Thu, 21 Jun 2018 15:37:51 -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=EDCZrv+eMl4xr7RVEe1OUTVzo60NpA5hOdG2uVBlW4g=; b=T6sRmnol+fb25ieqoFUSPI4x7 WuZf91BO7fA/jNQlU32m5ZeldT7nIT3S6UWLhlbOCuyAaHa89nnzmKX0c1JiIxLjEPLUE3BOTyzbd B83YQbYCN97BQIaGRDuX/FnDuhZPBQqCh+aY5C3sfEhjW9g/wLQZaRD4eXUxAQgT1e7NIzYUj9fIR Wxde3lXsy4AyUB7EdNfL1EYUge2PRuSEQeixvHoJi/lyJ8SvMvzXCtdJCh5FYLSkc6WwSyLTGN1s2 tejRG/fXoX+55mkYIxHdsYlkxldWQnkPVm8v9y663jdm+DaxVznzX2AVPKVsY8tzv1IBNdwsF4D65 FGA71RbPg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fW5Oo-00019a-MT; Thu, 21 Jun 2018 19:37:43 +0000 Received: by worktop (Postfix, from userid 1000) id 796376E093A; Thu, 21 Jun 2018 21:37:38 +0200 (CEST) Date: Thu, 21 Jun 2018 21:37:38 +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: <20180621193738.GA13636@worktop.programming.kicks-ass.net> References: <1527435965-202085-1-git-send-email-fenghua.yu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1527435965-202085-1-git-send-email-fenghua.yu@intel.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. > 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. > To detect split lock, a new control bit (bit 29) in per-core TEST_CTL > MSR 0x33 will be introduced in future x86 processors. When the bit 29 > is set, the processor causes #AC exception for split locked accesses at > all CPL. Per-Core is really unfortunate, but better than nothing.