From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754178AbbANRFo (ORCPT ); Wed, 14 Jan 2015 12:05:44 -0500 Received: from smtprelay0107.hostedemail.com ([216.40.44.107]:56175 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752542AbbANRFn (ORCPT ); Wed, 14 Jan 2015 12:05:43 -0500 X-Session-Marker: 6E657665747340676F6F646D69732E6F7267 X-Spam-Summary: 2,0,0,,d41d8cd98f00b204,rostedt@goodmis.org,:::::::::::::::::::,RULES_HIT:41:355:379:541:599:800:960:988:989:1260:1277:1311:1313:1314:1345:1359:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2393:2553:2559:2562:3138:3139:3140:3141:3142:3167:3352:3622:3865:3867:3868:3871:3872:3874:4250:5007:6119:6261:7875:10004:10400:10848:10967:11232:11658:11914:12517:12519:12740:13069:13255:13311:13357:14096:14097:21080,0,RBL:none,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fn,MSBL:0,DNSBL:none,Custom_rules:0:0:0 X-HE-Tag: walk88_142b169791d60 X-Filterd-Recvd-Size: 2149 Date: Wed, 14 Jan 2015 12:05:36 -0500 From: Steven Rostedt To: Borislav Petkov Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Masami Hiramatsu , vvs@sw.ru, "H. Peter Anvin" , Thomas Gleixner , x86-ml , stable@vger.kernel.org Subject: Re: [PATCH 3/3] ftrace/jprobes/x86: Fix conflict between jprobes and function graph tracing Message-ID: <20150114120536.4cccc3a9@gandalf.local.home> In-Reply-To: <20150114165537.GB6902@pd.tnic> References: <20150114153958.931152836@goodmis.org> <20150114154329.552437962@goodmis.org> <20150114165537.GB6902@pd.tnic> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; 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 List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 14 Jan 2015 17:55:37 +0100 Borislav Petkov wrote: > Err, stupid question: marking the jprobe handler "notrace" doesn't help? > A few reasons. One, that would require all users to make their handler as "notrace". That's not very reliable. Not to mention, I still work at Red Hat and we have this KABI thingy, where the jprobe modules don't need to change and we still need to fix it. This change is much more robust that expecting jprobe callers to add notrace. Two, I HATE when a notrace is added for function graph tracing that is not needed for function tracing. As I told Masami, every "notrace" added to the kernel makes function tracing that much more useless. Function tracing should be allowed to debug jprobes. Three, I have a patch that lets this all work if the kprobe/jprobes uses the ftrace fentry infrastructure (the work I original did). Why break everything for something the requires jprobe users to do things correctly? -- Steve