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 A0D26C432C0 for ; Fri, 22 Nov 2019 20:23:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 76A8820708 for ; Fri, 22 Nov 2019 20:23:23 +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="kD0jCrxu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727182AbfKVUXW (ORCPT ); Fri, 22 Nov 2019 15:23:22 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:44666 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726526AbfKVUXU (ORCPT ); Fri, 22 Nov 2019 15:23:20 -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=b8B+GByzGciEAQqjrUTAkbEpsryHD7CBv8tBnhLGMqc=; b=kD0jCrxubG3PD+ZkmYrsktw4h GAWC4pi692pSyYH7m743qVeRkACNun5WJxnzCqGy/jA0XbKgSvSHHw8SvxZ/bPy/YEe7npgyJjg8x RRevsZye991yu5xYsGKYEx7XW9W2jKQlgSOCdWekUiAz5ondiPjo+Qf8qqW7OMSLhv03F2bXSEWjk ydX7IJk4up8tvKnifslhcfsDO+0S0qpaFyKXUnLwVHifSG87hCG/O7EgYbyQyi/gGr0P3CjkJLyiu IfxvWo2Eg7zW7jjZQdENZRpxnxRw+aiRjRb7M1G8I8Y2uq7fkEy7MgtrW5uVwBzYPZupAweeX6T7D dnkczs4Kw==; 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 1iYFSU-0003ze-RW; Fri, 22 Nov 2019 20:23:15 +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 568FD30068E; Fri, 22 Nov 2019 21:22:01 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id C167B20321DB0; Fri, 22 Nov 2019 21:23:12 +0100 (CET) Date: Fri, 22 Nov 2019 21:23:12 +0100 From: Peter Zijlstra To: "Luck, Tony" Cc: Ingo Molnar , Fenghua Yu , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , 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: <20191122202312.GB2844@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> <20191121173444.GA5581@agluck-desk2.amr.corp.intel.com> <20191122105141.GY4114@hirez.programming.kicks-ass.net> <20191122152715.GA1909@hirez.programming.kicks-ass.net> <20191122172246.GA15557@agluck-desk2.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191122172246.GA15557@agluck-desk2.amr.corp.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 Fri, Nov 22, 2019 at 09:22:46AM -0800, Luck, Tony wrote: > On Fri, Nov 22, 2019 at 04:27:15PM +0100, Peter Zijlstra wrote: > > +void handle_user_split_lock(struct pt_regs *regs, long error_code) > > +{ > > + if (sld_state == sld_fatal) > > + return false; > > + > > + pr_alert("#AC: %s/%d took a split_lock trap at address: 0x%lx\n", > > + current->comm, current->pid, regs->ip); > > + > > + __sld_set_msr(false); > > + set_tsk_thread_flag(current, TIF_CLD); > > + return true; > > +} > > I think you need an extra check in here. While a #AC in the kernel > is an indication of a split lock. A user might have enabled alignment > checking and so this #AC might not be from a split lock. > > I think the extra code if just to change that first test to: > > if ((regs->eflags & X86_EFLAGS_AC) || sld_fatal) Indeed.