From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by sourceware.org (Postfix) with ESMTPS id 1D45D3858D35 for ; Thu, 23 Dec 2021 21:00:46 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 1D45D3858D35 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-487-X_kp357kPCGvzUIyz3IhGA-1; Thu, 23 Dec 2021 16:00:44 -0500 X-MC-Unique: X_kp357kPCGvzUIyz3IhGA-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 73B2D81CCB6; Thu, 23 Dec 2021 21:00:43 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.104]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7F46A108B9; Thu, 23 Dec 2021 21:00:42 +0000 (UTC) From: Florian Weimer To: "H.J. Lu" Cc: GNU C Library Subject: Re: [PATCH 0/4] _r_debug copy relocation support References: <871r23drd6.fsf@oldenburg.str.redhat.com> Date: Thu, 23 Dec 2021 22:00:40 +0100 In-Reply-To: (H. J. Lu's message of "Thu, 23 Dec 2021 12:47:21 -0800") Message-ID: <87v8zfc9zb.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.2 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.3 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_NONE, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Dec 2021 21:00:49 -0000 * H. J. Lu: > On Thu, Dec 23, 2021 at 11:59 AM Florian Weimer wrote: >> >> * H. J. Lu: >> >> > On Thu, Dec 23, 2021 at 10:43 AM Florian Weimer via Libc-alpha >> > wrote: >> >> >> >> I implemented this because we received a bug that the _r_debug extension >> >> mechanism broke dyninst. But it turns out it wasn't because of a copy >> >> relocation: dyninst has its own interposing *definition* of _r_debug, so >> >> the patch series doesn't solve this. It can only handle an interposing >> >> definition in the main executable, not one in shared object (although I >> >> guess in theory we could fix this). >> > >> > Why doesn't GDB suffer from this issue? >> >> I expect that GDB uses DT_DEBUG, and that's not subject to >> interposition, as before. > > Can dyninst also use DT_DEBUG? Not easily. They can keep using _r_debug if they just remove their local definition. Thanks, Florian