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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 DA562C433DF for ; Wed, 12 Aug 2020 07:25:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BFDEE20781 for ; Wed, 12 Aug 2020 07:25:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726894AbgHLHZP (ORCPT ); Wed, 12 Aug 2020 03:25:15 -0400 Received: from mga11.intel.com ([192.55.52.93]:5555 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726572AbgHLHZP (ORCPT ); Wed, 12 Aug 2020 03:25:15 -0400 IronPort-SDR: u14/qyfGAN1M6+KdpO1le6oggWkQdMz52bnjheWVsa2pXwDd8QSXQgZwVXAG4u8Oe3N1zGd8Lt wdwCn+Bp3rxw== X-IronPort-AV: E=McAfee;i="6000,8403,9710"; a="151564338" X-IronPort-AV: E=Sophos;i="5.76,303,1592895600"; d="scan'208";a="151564338" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2020 00:25:14 -0700 IronPort-SDR: qHt8VwgY50FkTckdc70a2iHnvd96zGZJpY0l7Echlm93Wf7ZwKzbLKs+ZtKDEAKg1J22lRNLT/ u+dbZ7R33RXg== X-IronPort-AV: E=Sophos;i="5.76,303,1592895600"; d="scan'208";a="469717800" Received: from likexu-mobl1.ccr.corp.intel.com (HELO [10.238.4.128]) ([10.238.4.128]) by orsmga005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Aug 2020 00:25:10 -0700 Subject: Re: [PATCH v1 2/2] perf/core: Fake regs for leaked kernel samples To: "Jin, Yao" , Peter Zijlstra Cc: mingo@redhat.com, oleg@redhat.com, acme@kernel.org, jolsa@kernel.org, Linux-kernel@vger.kernel.org, ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com, alexander.shishkin@linux.intel.com, mark.rutland@arm.com References: <20200731025617.16243-1-yao.jin@linux.intel.com> <20200731025617.16243-2-yao.jin@linux.intel.com> <20200804114900.GI2657@hirez.programming.kicks-ass.net> <4c958d61-11a7-9f3e-9e7d-d733270144a1@linux.intel.com> <20200805124454.GP2657@hirez.programming.kicks-ass.net> <797aa4de-c618-f340-ad7b-cef38c96b035@linux.intel.com> <56957a58-6292-e075-8c30-6230450e3518@linux.intel.com> <20200811075924.GU3982@worktop.programming.kicks-ass.net> <20200811084548.GW3982@worktop.programming.kicks-ass.net> <8bedaac0-2db1-b59c-581f-62f6d7a31c48@linux.intel.com> From: Like Xu Organization: Intel OTC Message-ID: Date: Wed, 12 Aug 2020 15:25:03 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <8bedaac0-2db1-b59c-581f-62f6d7a31c48@linux.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/8/12 11:52, Jin, Yao wrote: > Hi Peter, > > On 8/11/2020 4:45 PM, Peter Zijlstra wrote: >> On Tue, Aug 11, 2020 at 04:31:10PM +0800, Jin, Yao wrote: >>> Hi Peter, >>> >>> On 8/11/2020 3:59 PM, Peter Zijlstra wrote: >>>> On Tue, Aug 11, 2020 at 03:50:43PM +0800, Jin, Yao wrote: >>>>> Could I post v2 which basically refers to your patch but removes some >>>>> conditions since I see some issues in test if we use these conditions. >>>>> >>>>>    1. Remove '!event->attr.exclude_hv || !event->attr.exclude_host || >>>>>       !event->attr.exclude_guest' at the entry of sanitize_sample_regs(). >>>>> >>>>>    2. Remove '!attr.exclude_hv || !attr.exclude_host || >>>>> !attr.exclude_guest' >>>>>       at the perf_event_open syscall entry. >>>> >>>> exclude_host, maybe -- due to the dodgy semantics of it, but the others >>>> should definitely be there. >>>> >>> >>> exclude_guest and exclude_hv are tricky too. >>> >>> If we do 'perf record -e cycles:u' in both host and guest, we can see: >>> >>> event->attr.exclude_guest = 0 >>> >>> thus sanitize_sample_regs() returns regs directly even if exclude_kernel >>> = 1. >>> >>> And in guest, exclude_hv = 0, it's out of my expectation too. >> >> I'm confused, how can 'perf record -e cycles:u' _ever_ have >> exclude_guest=0, exclude_hv=0 ? That simply makes no sense and is utterly >> broken. >> >> You explicitly ask for userspace-only, reporting hypervisor or guest >> events is a straight up bug. Guest events = guest user-space events + guest kernel-space events. Some perf users on the host may only want to count guest user space events. >> > > If we run 'perf record -e cycles:u', > > 1. On host, exclude_guest = 0 and exclude_hv = 1 > > perf tool doesn't specially set 'exclude_guest' when it parses the 'u' > modifier. I agree that can be improved. I will post a perf tool patch to > fix that. > > 2. On guest, exclude_guest = 0 and exclude_hv = 0. > > For exclude_hv = 0, it looks like a bug but x86 doesn't use exclude_hv. But > yes, we should fix that. > > CC Like Xu . > > Thanks > Jin Yao