From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 91286 invoked by alias); 11 Mar 2016 18:17:11 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 91219 invoked by uid 89); 11 Mar 2016 18:17:10 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.7 required=5.0 tests=AWL,BAYES_00,RP_MATCHES_RCVD,SPF_PASS autolearn=ham version=3.3.2 spammy=HX-Received-From:4830, HX-Received-From:134, HX-Received-From:2001, HX-HELO:eggs.gnu.org X-HELO: eggs.gnu.org Received: from eggs.gnu.org (HELO eggs.gnu.org) (208.118.235.92) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-SHA encrypted) ESMTPS; Fri, 11 Mar 2016 18:17:09 +0000 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aeRcU-0002kp-A2 for gdb-patches@sourceware.org; Fri, 11 Mar 2016 13:17:07 -0500 Received: from fencepost.gnu.org ([2001:4830:134:3::e]:51302) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aeRcU-0002kl-6k; Fri, 11 Mar 2016 13:17:02 -0500 Received: from 84.94.185.246.cable.012.net.il ([84.94.185.246]:3921 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1aeRcT-0006ad-Cn; Fri, 11 Mar 2016 13:17:01 -0500 Date: Fri, 11 Mar 2016 18:17:00 -0000 Message-Id: <83shzwj2wt.fsf@gnu.org> From: Eli Zaretskii To: Pedro Alves CC: arnez@linux.vnet.ibm.com, koriakin@0x04.net, gdb-patches@sourceware.org In-reply-to: <56E2FA1B.7050808@redhat.com> (message from Pedro Alves on Fri, 11 Mar 2016 17:02:19 +0000) Subject: Re: [PATCH 4/8] gdb/s390: Fill gen_return_address hook. Reply-to: Eli Zaretskii References: <1453637529-26972-5-git-send-email-koriakin@0x04.net> <1454853751-18455-1-git-send-email-koriakin@0x04.net> <56E2AD82.3060101@0x04.net> <56E2B95F.7050701@0x04.net> <56E2E7C8.7050901@redhat.com> <56E2FA1B.7050808@redhat.com> MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4830:134:3::e X-IsSubscribed: yes X-SW-Source: 2016-03/txt/msg00197.txt.bz2 > Cc: Eli Zaretskii , > Marcin Kościelnicki > , > gdb-patches@sourceware.org > From: Pedro Alves > Date: Fri, 11 Mar 2016 17:02:19 +0000 > > > @item $_ret > > Collect the return address. This is helpful if you want to see more > > -of a backtrace. > > +of a backtrace. Note that the return address can not always be > > +determined reliably, and a wrong address may be collected instead. > > +The reliability is usually higher for tracepoints at function entry. > > Hmm, this reads a bit as if the backtrace will be incorrect/bogus > later on, which is not true. > > How about a merge of your suggestion with Marcin's previous reply, > and some extras on top: > > @item $_ret > Collect the set of memory addresses and/or registers necessary to compute > the frame's return address. This is helpful if you want to see > more of a backtrace. > > @emph{Note:} The necessary set can not always be reliability determined up > front, and the wrong address / registers may end up collected instead. > The reliability is usually higher for tracepoints at function entry. > When this happens, backtracing will stop because the return address > is found unavailable (unless another collect rule happened to match it). Maybe it's me, but I don't see the significant difference between these two versions. (And there's a typo in the second one: "reliability" should be "reliably".) Thanks.