From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 111218 invoked by alias); 9 Apr 2015 12:46:09 -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 111208 invoked by uid 89); 9 Apr 2015 12:46:09 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS,SPF_PASS,T_RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Thu, 09 Apr 2015 12:46:08 +0000 Received: from int-mx14.intmail.prod.int.phx2.redhat.com (int-mx14.intmail.prod.int.phx2.redhat.com [10.5.11.27]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id t39Ck7bD029062 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Thu, 9 Apr 2015 08:46:07 -0400 Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.ams2.redhat.com [10.39.146.11]) by int-mx14.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id t39Ck56e013832 for ; Thu, 9 Apr 2015 08:46:06 -0400 Message-ID: <5526748D.5060400@redhat.com> Date: Thu, 09 Apr 2015 12:46:00 -0000 From: Pedro Alves User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: gdb-patches@sourceware.org Subject: Re: [PATCH v2 03/23] PR13858 - Can't do displaced stepping with no symbols References: <1428410990-28560-1-git-send-email-palves@redhat.com> <1428410990-28560-4-git-send-email-palves@redhat.com> In-Reply-To: <1428410990-28560-4-git-send-email-palves@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2015-04/txt/msg00331.txt.bz2 On 04/07/2015 01:49 PM, Pedro Alves wrote: > Running break-interp.exp with the target always in non-stop mode trips > on PR13858, as enabling non-stop also enables displaced stepping. > > The problem is that when GDB doesn't know where the entry point is, it > doesn't know where to put the displaced stepping scratch pad. The > test added by this commit exercises this. Without the fix, we get: > > (gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: break *$pc > set displaced-stepping on > (gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: set displaced-stepping on > stepi > 0x00000000004005be in ?? () > Entry point address is not known. > (gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: stepi > p /x $pc > $2 = 0x4005be > (gdb) PASS: gdb.base/step-over-no-symbols.exp: displaced=on: get after PC > FAIL: gdb.base/step-over-no-symbols.exp: displaced=on: advanced > > The fix is to fall back to stepping over the breakpoint in-line if we > don't know where the entry point address is. > > This is enough to fix all-stop + "set displaced on". For non-stop, > we'll need to teach core gdb to pause all threads to be able to start > the in-line step-over (because then we need to remove the breakpoint > from the target temporarily). Hmm, actually not all targets get the entry point from symbols -- when Cell debugging is enabled, PPC gets the entry point from AT_ENTRY from the auxv... We should probably make that the default on GNU/Linux. I just tried that now on x86-64 and it worked fine. Thanks, Pedro Alves