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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 C1685C43381 for ; Mon, 1 Apr 2019 17:57:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 927F820880 for ; Mon, 1 Apr 2019 17:57:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554141458; bh=NG9vAxxYKSU/x+s+QLEQdi1P2/5YUpvQgB2pALodnP0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Brxs3/1J4mj3zc6PHH5rULwosiAUEzj9YvebbP3StmFNdFFOG0k0hIOhRsfHNNosm yQDrTX9x/AiNef20wEmNKNzkc2rFnO6+ECK7VflGqmr6nCF3i6Pg1QzaDVj8dcBDTP SyBc0aCziRfEP4vooO6T6qnRy7x07GvKRl2cnX34= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731350AbfDARTo (ORCPT ); Mon, 1 Apr 2019 13:19:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:47716 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731139AbfDARTm (ORCPT ); Mon, 1 Apr 2019 13:19:42 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5EF2521473; Mon, 1 Apr 2019 17:19:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554139181; bh=NG9vAxxYKSU/x+s+QLEQdi1P2/5YUpvQgB2pALodnP0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MYU2YLOmPMrj2jz9usZml0IlJKLrDLXnoowZoiRv0/5vAle2qUFJaw2dvEj8nvteu ctzhkS1by2Ch2S7+Zr3G90cy+l18CksH9ottfAI4nw3Rz5WKuu/DNLdOYLbdsKvTl5 bKu26jGG67zS00Y/1CYRPOh3LUuZyEE6yGYF3Vss= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Adrian Hunter , Jiri Olsa , Arnaldo Carvalho de Melo Subject: [PATCH 4.19 116/134] perf intel-pt: Fix TSC slip Date: Mon, 1 Apr 2019 19:02:32 +0200 Message-Id: <20190401170055.136710059@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190401170044.243719205@linuxfoundation.org> References: <20190401170044.243719205@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Adrian Hunter commit f3b4e06b3bda759afd042d3d5fa86bea8f1fe278 upstream. A TSC packet can slip past MTC packets so that the timestamp appears to go backwards. One estimate is that can be up to about 40 CPU cycles, which is certainly less than 0x1000 TSC ticks, but accept slippage an order of magnitude more to be on the safe side. Signed-off-by: Adrian Hunter Cc: Jiri Olsa Cc: stable@vger.kernel.org Fixes: 79b58424b821c ("perf tools: Add Intel PT support for decoding MTC packets") Link: http://lkml.kernel.org/r/20190325135135.18348-1-adrian.hunter@intel.com Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: Greg Kroah-Hartman --- tools/perf/util/intel-pt-decoder/intel-pt-decoder.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) --- a/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c +++ b/tools/perf/util/intel-pt-decoder/intel-pt-decoder.c @@ -251,19 +251,15 @@ struct intel_pt_decoder *intel_pt_decode if (!(decoder->tsc_ctc_ratio_n % decoder->tsc_ctc_ratio_d)) decoder->tsc_ctc_mult = decoder->tsc_ctc_ratio_n / decoder->tsc_ctc_ratio_d; - - /* - * Allow for timestamps appearing to backwards because a TSC - * packet has slipped past a MTC packet, so allow 2 MTC ticks - * or ... - */ - decoder->tsc_slip = multdiv(2 << decoder->mtc_shift, - decoder->tsc_ctc_ratio_n, - decoder->tsc_ctc_ratio_d); } - /* ... or 0x100 paranoia */ - if (decoder->tsc_slip < 0x100) - decoder->tsc_slip = 0x100; + + /* + * A TSC packet can slip past MTC packets so that the timestamp appears + * to go backwards. One estimate is that can be up to about 40 CPU + * cycles, which is certainly less than 0x1000 TSC ticks, but accept + * slippage an order of magnitude more to be on the safe side. + */ + decoder->tsc_slip = 0x10000; intel_pt_log("timestamp: mtc_shift %u\n", decoder->mtc_shift); intel_pt_log("timestamp: tsc_ctc_ratio_n %u\n", decoder->tsc_ctc_ratio_n);