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,URIBL_BLOCKED,USER_AGENT_SANE_2 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 B7E39C32751 for ; Wed, 31 Jul 2019 15:25:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 92C9E20659 for ; Wed, 31 Jul 2019 15:25:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729371AbfGaPZn (ORCPT ); Wed, 31 Jul 2019 11:25:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:35318 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727926AbfGaPZn (ORCPT ); Wed, 31 Jul 2019 11:25:43 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 B65E420659; Wed, 31 Jul 2019 15:25:41 +0000 (UTC) Date: Wed, 31 Jul 2019 11:25:39 -0400 From: Steven Rostedt To: Masami Hiramatsu Cc: Ingo Molnar , linux-kernel@vger.kernel.org, Tom Zanussi , Ravi Bangoria , Namhyung Kim , Arnaldo Carvalho de Melo Subject: Re: [PATCH v2 00/12] tracing/probe: Add multi-probes per event support Message-ID: <20190731112539.1efac604@gandalf.local.home> In-Reply-To: <156095682948.28024.14190188071338900568.stgit@devnote2> References: <156095682948.28024.14190188071338900568.stgit@devnote2> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 20 Jun 2019 00:07:09 +0900 Masami Hiramatsu wrote: > Hello, > > This is the 2nd version of multi-probes per event support on ftrace > and perf-tools. > > Previous version is here; > https://lkml.org/lkml/2019/5/31/573 > > >From this version, I omitted first 9 patches which has been picked > to Steve's tree. > In this version, I've fixed some bugs and hardened some unexpected > error cases according to Steve's comment. > Here are changes in this version: > > - [1/12] This have below changes. > - Warn if the primary trace_probe does not exist. > - Fix enable_trace_kprobe() to not return error if the any probes > are "gone" state. If all probes have gone or any other error > reason, the event can not be enabled and return error. > - Fix trace_probe_enable() to roll back all enabled uprobe if > any one of uprobe is failed to enable. > - [7/12] Swap the checking order of filename for avoiding unexpected > memory access. > > > ==== > For trace-event, we can insert same trace-event on several places > on the code, and those can record similar information as a same event > with same format. > > This series implements similar feature on probe-event. Since the probe > event is based on the compiled binary, sometimes we find that the target > source line is complied into several different addresses, e.g. inlined > function, unrolled loop, etc. In those cases, it is useful to put a > same probe-event on different addresses. > > With this series, we can append multi probes on one event as below > > # echo p:testevent _do_fork r1=%ax r2=%dx > kprobe_events > # echo p:testevent fork_idle r1=%ax r2=%cx >> kprobe_events > # kprobe_events > p:kprobes/testevent _do_fork r1=%ax r2=%dx > p:kprobes/testevent fork_idle r1=%ax r2=%cx > > This means testevent is hit on both of _do_fork and fork_idle. > As you can see, the appended event must have same number of arguments > and those must have same 'type' and 'name' as original one. This is like > a function signature, it checks whether the appending event has the same > type and name of event arguments and same probe type, but doesn't care > about the assignment. > > So, below appending commands will be rejected. > > # echo p:testevent _do_fork r1=%ax r2=%dx > kprobe_events > # echo p:testevent fork_idle r1=%ax >> kprobe_events > (No 2nd argument) > # echo p:testevent fork_idle r1=%ax r2=%ax:x8 >> kprobe_events > (The type of 2nd argument is different) > > If one inlined code has an argument on a register, but another > inlined code has fixed value (as a result of optimization), > you can also specify the fixed immediate value, e.g. > > # echo p:testevent _do_fork r1=%ax r2=%dx > kprobe_events > # echo p:testevent fork_idle r1=%ax r2=\1 >> kprobe_events > > Hi Masami, I applied this patch set to my queue. Nice feature! I'll probably be testing it a bit more. I wont be pushing it to my repo until v5.3-rc3 comes out, as I'll plan on rebasing my for-next branch on that. Thanks! -- Steve