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=-2.2 required=3.0 tests=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 02879C432C0 for ; Fri, 22 Nov 2019 17:22:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CF9DA20714 for ; Fri, 22 Nov 2019 17:22:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727368AbfKVRWr (ORCPT ); Fri, 22 Nov 2019 12:22:47 -0500 Received: from mga18.intel.com ([134.134.136.126]:7187 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726620AbfKVRWr (ORCPT ); Fri, 22 Nov 2019 12:22:47 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 22 Nov 2019 09:22:46 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,230,1571727600"; d="scan'208";a="197686701" Received: from agluck-desk2.sc.intel.com (HELO agluck-desk2.amr.corp.intel.com) ([10.3.52.68]) by orsmga007.jf.intel.com with ESMTP; 22 Nov 2019 09:22:44 -0800 Date: Fri, 22 Nov 2019 09:22:46 -0800 From: "Luck, Tony" To: Peter Zijlstra 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: <20191122172246.GA15557@agluck-desk2.amr.corp.intel.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191122152715.GA1909@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.12.1 (2019-06-15) 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 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) -Tony