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=-2.4 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 3539916256E1 for ; Mon, 30 Jul 2018 16:17:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DA19E20894 for ; Mon, 30 Jul 2018 16:17:47 +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="EA/h80vv" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DA19E20894 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 S1730592AbeG3Rx1 (ORCPT ); Mon, 30 Jul 2018 13:53:27 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:53714 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726912AbeG3Rx1 (ORCPT ); Mon, 30 Jul 2018 13:53:27 -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=xZBrz5ToQWG8+o4OIXs1moVLnTDYBtGWf3mZpASMw4Q=; b=EA/h80vvzPaKJYCtV6sOCLTc5 FzDoh/hr9rWw1wYe6IV4cVRguR28wF4wbLsuj1g4srisgRs20bH3V5jINEGyLJSCDI2k9DSP+wwSs llaV5F2fdR+x6lfALB0CeVE08DenjZaeglSGglT0ZTzuvwzkvu2828if9aOJGAIFWQg4zH9YINwCr fgjlVJlDbLjiIkEwknv4wCVgQ9MHXL2oAyE4T3teF3O8VjbqCrJ7AIpLjf1NIcG3sC7EUvHU1QZPz cAO2SsxB7zWZGBbJ9ecco6b6qa7Il+uEA9M+91Tr6ooswb5AD/S5LOrDs3PP+cn863HNZeb4FaTmp jIkzdKBuA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fkArc-0004yH-Cp; Mon, 30 Jul 2018 16:17:40 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D039120275F3E; Mon, 30 Jul 2018 18:17:38 +0200 (CEST) Date: Mon, 30 Jul 2018 18:17:38 +0200 From: Peter Zijlstra To: Jacek Tomaka Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, tglx@linutronix.de, Jacek Tomaka Subject: Re: [PATCH v2] perf/x86/intel: Add support for MISPREDICT bit on Knights Landing cpus Message-ID: <20180730161738.GL2494@hirez.programming.kicks-ass.net> References: <20180730142813.13451-1-jacekt@dugeo.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180730142813.13451-1-jacekt@dugeo.com> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 30, 2018 at 10:28:13PM +0800, Jacek Tomaka wrote: > From: Jacek Tomaka > > Problem: perf did not show branch predicted/mispredicted bit in brstack. > > Output of perf -F brstack for profile collected > > Before: > 0x4fdbcd/0x4fdc03/-/-/-/0 > 0x45f4c1/0x4fdba0/-/-/-/0 > 0x45f544/0x45f4bb/-/-/-/0 > 0x45f555/0x45f53c/-/-/-/0 > 0x7f66901cc24b/0x45f555/-/-/-/0 > 0x7f66901cc22e/0x7f66901cc23d/-/-/-/0 > 0x7f66901cc1ff/0x7f66901cc20f/-/-/-/0 > 0x7f66901cc1e8/0x7f66901cc1fc/-/-/-/0 > > After: > 0x4fdbcd/0x4fdc03/P/-/-/0 > 0x45f4c1/0x4fdba0/P/-/-/0 > 0x45f544/0x45f4bb/P/-/-/0 > 0x45f555/0x45f53c/P/-/-/0 > 0x7f66901cc24b/0x45f555/P/-/-/0 > 0x7f66901cc22e/0x7f66901cc23d/P/-/-/0 > 0x7f66901cc1ff/0x7f66901cc20f/P/-/-/0 > 0x7f66901cc1e8/0x7f66901cc1fc/P/-/-/0 > > Cause: > As mentioned in Software Development Manual vol 3, 17.4.8.1, > IA32_PERF_CAPABILITIES[5:0] indicates the format of the address that is > stored in the LBR stack. Knights Landing reports 1 (LBR_FORMAT_LIP) as > its format. Despite that, registers containing FROM address of the branch, > do have MISPREDICT bit but because of the format indicated in > IA32_PERF_CAPABILITIES[5:0], LBR did not read MISPREDICT bit. > > Solution: > Teach LBR about above Knights Landing quirk and make it read MISPREDICT bit. > --- > arch/x86/events/intel/lbr.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c > index cf372b9055..043aa09f3a 100644 > --- a/arch/x86/events/intel/lbr.c > +++ b/arch/x86/events/intel/lbr.c > @@ -19,7 +19,7 @@ enum { > LBR_FORMAT_MAX_KNOWN = LBR_FORMAT_TIME, > }; > > -static const enum { > +static enum { > LBR_EIP_FLAGS = 1, > LBR_TSX = 2, > } lbr_desc[LBR_FORMAT_MAX_KNOWN + 1] = { > @@ -1230,4 +1230,8 @@ void intel_pmu_lbr_init_knl(void) > > x86_pmu.lbr_sel_mask = LBR_SEL_MASK; > x86_pmu.lbr_sel_map = snb_lbr_sel_map; > + > + /* Knights Landing does have MISPREDICT bit */ > + if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_LIP) > + lbr_desc[LBR_FORMAT_LIP] |= LBR_EIP_FLAGS; > } So why not set lbr_format to LBR_FORMAT_EIP_FLAGS ?