From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io1-f72.google.com (mail-io1-f72.google.com [209.85.166.72]) by kanga.kvack.org (Postfix) with ESMTP id E071D6B0007 for ; Wed, 31 Oct 2018 18:24:45 -0400 (EDT) Received: by mail-io1-f72.google.com with SMTP id s15-v6so15498282iob.11 for ; Wed, 31 Oct 2018 15:24:45 -0700 (PDT) Received: from gate.crashing.org (gate.crashing.org. [63.228.1.57]) by mx.google.com with ESMTPS id d1-v6si13478716ita.120.2018.10.31.15.24.44 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 31 Oct 2018 15:24:44 -0700 (PDT) Message-ID: <3da6549832ef68b93b210d5a32b3f12f3565cab0.camel@kernel.crashing.org> Subject: Re: PIE binaries are no longer mapped below 4 GiB on ppc64le From: Benjamin Herrenschmidt 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" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Florian Weimer , Michal =?ISO-8859-1?Q?Such=E1nek?= Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, Nick Piggin , Anton Blanchard 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.