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=-2.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 97242ECDFB8 for ; Mon, 23 Jul 2018 12:55:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5492520875 for ; Mon, 23 Jul 2018 12:55:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5492520875 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.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 S2388502AbeGWN4H (ORCPT ); Mon, 23 Jul 2018 09:56:07 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:45076 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388088AbeGWN0f (ORCPT ); Mon, 23 Jul 2018 09:26:35 -0400 Received: from localhost (LFbn-1-12238-233.w90-92.abo.wanadoo.fr [90.92.53.233]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 01757BD4; Mon, 23 Jul 2018 12:25:38 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hugh Dickins , Thomas Gleixner , Peter Zijlstra , Arnaldo Carvalho de Melo , Alexander Shishkin , Andi Kleen , Dave Hansen , Stephane Eranian Subject: [PATCH 4.17 11/63] x86/events/intel/ds: Fix bts_interrupt_threshold alignment Date: Mon, 23 Jul 2018 14:24:17 +0200 Message-Id: <20180723122446.802635463@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180723122446.351334162@linuxfoundation.org> References: <20180723122446.351334162@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hugh Dickins commit 2c991e408df6a407476dbc453d725e1e975479e7 upstream. Markus reported that BTS is sporadically missing the tail of the trace in the perf_event data buffer: [decode error (1): instruction overflow] shown in GDB; and bisected it to the conversion of debug_store to PTI. A little "optimization" crept into alloc_bts_buffer(), which mistakenly placed bts_interrupt_threshold away from the 24-byte record boundary. Intel SDM Vol 3B 17.4.9 says "This address must point to an offset from the BTS buffer base that is a multiple of the BTS record size." Revert "max" from a byte count to a record count, to calculate the bts_interrupt_threshold correctly: which turns out to fix problem seen. Fixes: c1961a4631da ("x86/events/intel/ds: Map debug buffers in cpu_entry_area") Reported-and-tested-by: Markus T Metzger Signed-off-by: Hugh Dickins Signed-off-by: Thomas Gleixner Cc: Peter Zijlstra Cc: Arnaldo Carvalho de Melo Cc: Alexander Shishkin Cc: Andi Kleen Cc: Dave Hansen Cc: Stephane Eranian Cc: stable@vger.kernel.org # v4.14+ Link: https://lkml.kernel.org/r/alpine.LSU.2.11.1807141248290.1614@eggly.anvils Signed-off-by: Greg Kroah-Hartman --- arch/x86/events/intel/ds.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/arch/x86/events/intel/ds.c +++ b/arch/x86/events/intel/ds.c @@ -408,9 +408,11 @@ static int alloc_bts_buffer(int cpu) ds->bts_buffer_base = (unsigned long) cea; ds_update_cea(cea, buffer, BTS_BUFFER_SIZE, PAGE_KERNEL); ds->bts_index = ds->bts_buffer_base; - max = BTS_RECORD_SIZE * (BTS_BUFFER_SIZE / BTS_RECORD_SIZE); - ds->bts_absolute_maximum = ds->bts_buffer_base + max; - ds->bts_interrupt_threshold = ds->bts_absolute_maximum - (max / 16); + max = BTS_BUFFER_SIZE / BTS_RECORD_SIZE; + ds->bts_absolute_maximum = ds->bts_buffer_base + + max * BTS_RECORD_SIZE; + ds->bts_interrupt_threshold = ds->bts_absolute_maximum - + (max / 16) * BTS_RECORD_SIZE; return 0; }