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 D223FC33C9E for ; Sat, 11 Jan 2020 09:57:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A526620848 for ; Sat, 11 Jan 2020 09:57:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729177AbgAKJ52 (ORCPT ); Sat, 11 Jan 2020 04:57:28 -0500 Received: from mga11.intel.com ([192.55.52.93]:11196 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728808AbgAKJ52 (ORCPT ); Sat, 11 Jan 2020 04:57:28 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by fmsmga102.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jan 2020 01:57:27 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,420,1571727600"; d="scan'208";a="240570568" Received: from linux.intel.com ([10.54.29.200]) by orsmga002.jf.intel.com with ESMTP; 11 Jan 2020 01:57:27 -0800 Received: from [10.252.24.8] (abudanko-mobl.ccr.corp.intel.com [10.252.24.8]) by linux.intel.com (Postfix) with ESMTP id 380C858045A; Sat, 11 Jan 2020 01:57:19 -0800 (PST) Subject: Re: [PATCH v4 2/9] perf/core: open access for CAP_SYS_PERFMON privileged process To: arnaldo.melo@gmail.com, Song Liu , Masami Hiramatsu Cc: Peter Zijlstra , Ingo Molnar , "jani.nikula@linux.intel.com" , "joonas.lahtinen@linux.intel.com" , "rodrigo.vivi@intel.com" , Alexei Starovoitov , Benjamin Herrenschmidt , Paul Mackerras , Michael Ellerman , "james.bottomley@hansenpartnership.com" , Serge Hallyn , James Morris , Will Deacon , Mark Rutland , Casey Schaufler , Robert Richter , Jiri Olsa , Andi Kleen , Stephane Eranian , Igor Lubashev , Alexander Shishkin , Namhyung Kim , linux-kernel References: <20200108160713.GI2844@hirez.programming.kicks-ass.net> <20200110140234.GO2844@hirez.programming.kicks-ass.net> <20200111005213.6dfd98fb36ace098004bde0e@kernel.org> <20200110164531.GA2598@kernel.org> <20200111084735.0ff01c758bfbfd0ae2e1f24e@kernel.org> <2B79131A-3F76-47F5-AAB4-08BCA820473F@fb.com> <5e191833.1c69fb81.8bc25.a88c@mx.google.com> From: Alexey Budankov Organization: Intel Corp. Message-ID: <158a4033-f8d6-8af7-77b0-20e62ec913b0@linux.intel.com> Date: Sat, 11 Jan 2020 12:57:18 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <5e191833.1c69fb81.8bc25.a88c@mx.google.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11.01.2020 3:35, arnaldo.melo@gmail.com wrote: > ,Jann Horn ,Thomas Gleixner ,Tvrtko Ursulin ,Lionel Landwerlin ,linux-kernel ,"linux-security-module@vger.kernel.org" ,"selinux@vger.kernel.org" ,"intel-gfx@lists.freedesktop.org" ,"bpf@vger.kernel.org" ,"linux-parisc@vger.kernel.org" ,"linuxppc-dev@lists.ozlabs.org" ,"linux-perf-users@vger.kernel.org" ,"linux-arm-kernel@lists.infradead.org" ,"oprofile-list@lists.sf.net" > From: Arnaldo Carvalho de Melo > Message-ID: > > On January 10, 2020 9:23:27 PM GMT-03:00, Song Liu wrote: >> >> >>> On Jan 10, 2020, at 3:47 PM, Masami Hiramatsu >> wrote: >>> >>> On Fri, 10 Jan 2020 13:45:31 -0300 >>> Arnaldo Carvalho de Melo wrote: >>> >>>> Em Sat, Jan 11, 2020 at 12:52:13AM +0900, Masami Hiramatsu escreveu: >>>>> On Fri, 10 Jan 2020 15:02:34 +0100 Peter Zijlstra >> wrote: >>>>>> Again, this only allows attaching to previously created kprobes, >> it does >>>>>> not allow creating kprobes, right? >>>> >>>>>> That is; I don't think CAP_SYS_PERFMON should be allowed to create >>>>>> kprobes. >>>> >>>>>> As might be clear; I don't actually know what the user-ABI is for >>>>>> creating kprobes. >>>> >>>>> There are 2 ABIs nowadays, ftrace and ebpf. perf-probe uses ftrace >> interface to >>>>> define new kprobe events, and those events are treated as >> completely same as >>>>> tracepoint events. On the other hand, ebpf tries to define new >> probe event >>>>> via perf_event interface. Above one is that interface. IOW, it >> creates new kprobe. >>>> >>>> Masami, any plans to make 'perf probe' use the perf_event_open() >>>> interface for creating kprobes/uprobes? >>> >>> Would you mean perf probe to switch to perf_event_open()? >>> No, perf probe is for setting up the ftrace probe events. I think we >> can add an >>> option to use perf_event_open(). But current kprobe creation from >> perf_event_open() >>> is separated from ftrace by design. >> >> I guess we can extend event parser to understand kprobe directly. >> Instead of >> >> perf probe kernel_func >> perf stat/record -e probe:kernel_func ... >> >> We can just do >> >> perf stat/record -e kprobe:kernel_func ... > > > You took the words from my mouth, exactly, that is a perfect use case, an alternative to the 'perf probe' one of making a disabled event that then gets activated via record/stat/trace, in many cases it's better, removes the explicit probe setup case. Arnaldo, Masami, Song, What do you think about making this also open to CAP_SYS_PERFMON privileged processes? Could you please also review and comment on patch 5/9 for bpf_trace.c? Thanks, Alexey > > Regards, > > - Arnaldo > >> >> Thanks, >> Song >