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 12F4F385BF9B for ; Mon, 20 Dec 2021 13:19:03 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 12F4F385BF9B 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-21-dSy5fxC5NO6zYLO1nCigfQ-1; Mon, 20 Dec 2021 08:18:54 -0500 X-MC-Unique: dSy5fxC5NO6zYLO1nCigfQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0BF6310151E0; Mon, 20 Dec 2021 13:18:53 +0000 (UTC) Received: from oldenburg.str.redhat.com (unknown [10.39.192.104]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9D58C7A2E9; Mon, 20 Dec 2021 13:18:46 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Cc: libc-alpha@sourceware.org, John Mellor-Crummey , Ben Woodard Subject: Re: [PATCH v6 14/20] elf: Issue audit la_objopen() for vDSO References: <20211115183734.531155-1-adhemerval.zanella@linaro.org> <20211115183734.531155-15-adhemerval.zanella@linaro.org> <878rwhheem.fsf@oldenburg.str.redhat.com> <98044a74-6b2a-8b53-aecf-1d4832264e6a@linaro.org> Date: Mon, 20 Dec 2021 14:18:45 +0100 In-Reply-To: <98044a74-6b2a-8b53-aecf-1d4832264e6a@linaro.org> (Adhemerval Zanella's message of "Mon, 20 Dec 2021 09:50:31 -0300") Message-ID: <87tuf3h0sq.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 2.79 on 10.5.11.16 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: Mon, 20 Dec 2021 13:19:05 -0000 * Adhemerval Zanella: >>> +unsigned int >>> +la_version (unsigned int version) >>> +{ >>> + return LAV_CURRENT; >>> +} >>> + >>> +unsigned int >>> +la_objopen (struct link_map *map, Lmid_t lmid, uintptr_t *cookie) >>> +{ >>> + /* The linux-gate.so is placed at a fixed address, thus l_addr being 0, >>> + and it might be the value reported as the AT_SYSINFO_EHDR. */ >>> + if (map->l_addr == 0 && startswith (map->l_name, "linux-gate.so")) >>> + fprintf (stderr, "vdso found: %p\n", NULL); >>> + else if (map->l_addr == getauxval (AT_SYSINFO_EHDR)) >>> + fprintf (stderr, "vdso found: %p\n", (void*) map->l_addr); >>> + >>> + return 0; >>> +} >> >> Would it be possible to look at the program headers to get the minimum >> mapped address for the linux-gate.so object? > > It should be possible, but I only saw it on a ia64 machine (which I don't > have access anymore) and reading the kernel source linux-gate.so is > provided also for x86, sh, and sparc 32-bits kernels. I am not sure > if it worth the trouble. Fair enough, keep the current version then. Thanks, Florian