From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 92864 invoked by alias); 23 Sep 2019 07:43:00 -0000 Mailing-List: contact gcc-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-owner@gcc.gnu.org Received: (qmail 92814 invoked by uid 89); 23 Sep 2019 07:42:57 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_PASS autolearn=ham version=3.3.1 spammy= X-HELO: mailout.enyo.de Received: from mailout.enyo.de (HELO mailout.enyo.de) (116.203.30.208) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Mon, 23 Sep 2019 07:42:55 +0000 Received: from [172.17.203.2] (helo=deneb.enyo.de) by albireo.enyo.de with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) id 1iCIzk-0000ig-NH; Mon, 23 Sep 2019 07:42:52 +0000 Received: from fw by deneb.enyo.de with local (Exim 4.92) (envelope-from ) id 1iCIzk-0006WL-HQ; Mon, 23 Sep 2019 09:42:52 +0200 From: Florian Weimer To: binutils@sourceware.org, libc-alpha@sourceware.org, gcc@gcc.gnu.org Subject: POWER PC-relative addressing and new text relocations Date: Mon, 23 Sep 2019 07:43:00 -0000 Message-ID: <87o8zbcvb7.fsf@mid.deneb.enyo.de> MIME-Version: 1.0 Content-Type: text/plain X-IsSubscribed: yes X-SW-Source: 2019-09/txt/msg00186.txt.bz2 At Cauldron, the question came up whether the dynamic loader needs to be taught about the new relocations for PC-relative addressing. I think they would only matter if we supported PC-relative addressing *and* text relocations. Is that really necessary? These text relocations would not work reliably anyway because the maximum displacement is not large enough. For example, with the current process layout, it's impossible to reach shared objects from the main program and vice versa. And some systems might want to add additional randomization, so that shared objects are not mapped closed together anymore.