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 [216.205.24.124]) by sourceware.org (Postfix) with ESMTP id 6D66C385780F for ; Fri, 12 Feb 2021 17:21:28 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 6D66C385780F Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-487-wdfpHCMqOXGOeQYL3Efofw-1; Fri, 12 Feb 2021 12:21:24 -0500 X-MC-Unique: wdfpHCMqOXGOeQYL3Efofw-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BC0ED801962; Fri, 12 Feb 2021 17:21:22 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-113-131.ams2.redhat.com [10.36.113.131]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7A3E660BE5; Fri, 12 Feb 2021 17:21:21 +0000 (UTC) From: Florian Weimer To: Adhemerval Zanella Cc: libc-alpha@sourceware.org, Raoni Fassina Firmino , Tulio Magno Quites Machado Filho Subject: Re: [PATCH] powerpc: Remove backtrace implementation References: <20210212170941.1786380-1-adhemerval.zanella@linaro.org> Date: Fri, 12 Feb 2021 18:21:43 +0100 In-Reply-To: <20210212170941.1786380-1-adhemerval.zanella@linaro.org> (Adhemerval Zanella's message of "Fri, 12 Feb 2021 14:09:41 -0300") Message-ID: <878s7ti4m0.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.7 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_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) 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: Fri, 12 Feb 2021 17:21:30 -0000 * Adhemerval Zanella: > The powerpc optimization to provide a fast stacktrace requires some > ad-hoc code to handle Linux signal frames and the change is fragile > once the kernel decides to slight change its execution sequence [1]. > > The generic implementation work as-is and it should be future proof > since the kernel provides the expected CFI directives in vDSO shared > page. > > Checked on powerpc-linux-gnu, powerpc64le-linux-gnu, and > powerpc64-linux-gnu. > > [1] https://sourceware.org/pipermail/libc-alpha/2021-January/122027.html Does this really work well (enough) on systems which do not build everything with asynchronous unwind tables? If I recall correctly, GCC enabled them by default only quite recently. Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill