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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 1D869C433E0 for ; Sun, 7 Mar 2021 06:30:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D60F465049 for ; Sun, 7 Mar 2021 06:30:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230147AbhCGGaK (ORCPT ); Sun, 7 Mar 2021 01:30:10 -0500 Received: from gate.crashing.org ([63.228.1.57]:38712 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229619AbhCGGaB (ORCPT ); Sun, 7 Mar 2021 01:30:01 -0500 Received: from gate.crashing.org (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id 1276NdCi026488; Sun, 7 Mar 2021 00:23:39 -0600 Received: (from segher@localhost) by gate.crashing.org (8.14.1/8.14.1/Submit) id 1276NbRn026484; Sun, 7 Mar 2021 00:23:37 -0600 X-Authentication-Warning: gate.crashing.org: segher set sender to segher@kernel.crashing.org using -f Date: Sun, 7 Mar 2021 00:23:36 -0600 From: Segher Boessenkool To: Fangrui Song Cc: Michael Ellerman , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, clang-built-linux , Alexey Kardashevskiy Subject: Re: [PATCH] Replace __toc_start + 0x8000 with .TOC. Message-ID: <20210307062336.GD29191@gate.crashing.org> References: <20210307051433.2756645-1-maskray@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210307051433.2756645-1-maskray@google.com> User-Agent: Mutt/1.4.2.3i Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi! On Sat, Mar 06, 2021 at 09:14:33PM -0800, Fangrui Song wrote: > TOC relocations are like GOT relocations on other architectures. > However, unlike other architectures, GNU ld's ppc64 port defines .TOC. > relative to the .got output section instead of the linker synthesized > .got input section. LLD defines .TOC. as the .got input section plus > 0x8000. When CONFIG_PPC_OF_BOOT_TRAMPOLINE=y, > arch/powerpc/kernel/prom_init.o is built, and LLD computed .TOC. can be > different from __toc_start defined by the linker script. > > Simplify kernel_toc_addr with asm label .TOC. so that we can get rid of > __toc_start. > > With this change, powernv_defconfig with CONFIG_PPC_OF_BOOT_TRAMPOLINE=y > is bootable with LLD. There is still an untriaged issue with Alexey's > configuration. Do you have any explanation why this *does* work, while the original doesn't? Some explanation that says *what* is wrong. To me it doesn't look like the kernel script is. Segher