From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9E762C0044C for ; Wed, 31 Oct 2018 22:26:49 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1FFE22064C for ; Wed, 31 Oct 2018 22:26:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1FFE22064C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 42ljcR0dqqzF3LY for ; Thu, 1 Nov 2018 09:26:47 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: lists.ozlabs.org; spf=permerror (mailfrom) smtp.mailfrom=kernel.crashing.org (client-ip=63.228.1.57; helo=gate.crashing.org; envelope-from=benh@kernel.crashing.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 42ljZ83ZHnzF3HY for ; Thu, 1 Nov 2018 09:24:48 +1100 (AEDT) Received: from localhost (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id w9VMOTXF003676; Wed, 31 Oct 2018 17:24:30 -0500 Message-ID: <3da6549832ef68b93b210d5a32b3f12f3565cab0.camel@kernel.crashing.org> Subject: Re: PIE binaries are no longer mapped below 4 GiB on ppc64le From: Benjamin Herrenschmidt To: Florian Weimer , Michal =?ISO-8859-1?Q?Such=E1nek?= Date: Thu, 01 Nov 2018 09:24:29 +1100 In-Reply-To: <877ehyf1cj.fsf@oldenburg.str.redhat.com> References: <87k1lyf2x3.fsf@oldenburg.str.redhat.com> <20181031185032.679e170a@naga.suse.cz> <877ehyf1cj.fsf@oldenburg.str.redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.1 (3.30.1-1.fc29) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-mm@kvack.org, Anton Blanchard , linuxppc-dev@lists.ozlabs.org, Nick Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Wed, 2018-10-31 at 18:54 +0100, Florian Weimer wrote: > > It would matter to C code which returns the address of a global variable > in the main program through and (implicit) int return value. > > The old behavior hid some pointer truncation issues. Hiding bugs like that is never a good idea.. > > Maybe it would be good idea to generate 64bit relocations on 64bit > > targets? > > Yes, the Go toolchain definitely needs fixing for PIE. I don't dispute > that. There was never any ABI guarantee that programs would be loaded below 4G... it just *happened*, so that's not per-se an ABI change. That said, I'm surprised of the choice of address.. I would have rather moved to above 1TB to benefit from 1T segments... Nick, Anton, do you know anything about that change ? Ben.