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=-16.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL 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 31A71C2BA19 for ; Mon, 13 Apr 2020 15:34:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 08D6820739 for ; Mon, 13 Apr 2020 15:34:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="o8Ku15Vy" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730511AbgDMPe6 (ORCPT ); Mon, 13 Apr 2020 11:34:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54720 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728263AbgDMPe5 (ORCPT ); Mon, 13 Apr 2020 11:34:57 -0400 Received: from mail-pj1-x1044.google.com (mail-pj1-x1044.google.com [IPv6:2607:f8b0:4864:20::1044]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6FA5BC0A3BDC for ; Mon, 13 Apr 2020 08:34:57 -0700 (PDT) Received: by mail-pj1-x1044.google.com with SMTP id np9so3962300pjb.4 for ; Mon, 13 Apr 2020 08:34:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ghs4l4nI57la7hO/6EnhN56epQlSYo2HQcGuqn9At3E=; b=o8Ku15VylZmW9RmUdw3LqYItOHWR5uR+BhCzrC4IOozU56RYAeexGHQrmUeAjY0cUB oqwdCBwanWaSy1xBLCk53ZHMr0WWy/+2ket481Z6niFhhrc1+dWnLe5NB0+Nn1LJ6biM pe8iK7TQ1s0nB7ksBzQ942wAKyrtwrXKLYFgYaIvevq/AR/mS2kBX0vDrjFGK53Lf7p7 c7GfBtx0lCLZqVjnntovV3+Cf4/aC7VzdGF04fTeHCWdsbTI9HSsEVToZFo+vKm/F9Gx IpT1KUmj0ARujnTGKsn2qx/2/EzWBZVSaTzIWz6v5uatfnpEq/LCceAV5vOou0azpcxt 5mWA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ghs4l4nI57la7hO/6EnhN56epQlSYo2HQcGuqn9At3E=; b=oeJ1j2UlLBQ6NkCgqhcYdiEiVdbpRsRYzIpCgdsI4JTdrDqcfOxHSZhaKDX9ZYS1j3 5U/8IOnh4I/cEAYzzw04ZcLqGGYI3IJT20EWFyKM/LEYcwEQGO2kZow9utF/b97ZM7LI Xu3l/n8b1mSxVnD1kipP9YOCsZZn4GG/B5LJcAyDs3FJUxzCeEhVDwwiOr28ly0zEVoI evX6weJMTlJ82xFUbFxsb5Fy1p/1RobyQcCvsvlq3elcRrLFSgosse6b7UOQBb5kS+Hg vAMligbChurbwWGshU7E+k+vKX9mwhapc4KGZjRr2SgRmdWOz5Pv20tgy73vQe2AZ1Aw NiAw== X-Gm-Message-State: AGi0PuY3+7Hpmad4G+sJyoFS7AKRs5SI1OgL61KnyWRnNp258fbcC/6l egn/R5cDBjFywjqsLIqheyaHmQ== X-Google-Smtp-Source: APiQypI6Dvk7gIIjLIxzrGkUSM2NUDSzxSvhD2oYSFiXn15uxg9GYJwz0R4Bsuz7njjnFBRvvCEVGw== X-Received: by 2002:a17:902:ac85:: with SMTP id h5mr17038570plr.76.1586792096747; Mon, 13 Apr 2020 08:34:56 -0700 (PDT) Received: from google.com ([2620:15c:2ce:0:9efe:9f1:9267:2b27]) by smtp.gmail.com with ESMTPSA id q12sm8205213pgi.86.2020.04.13.08.34.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Apr 2020 08:34:56 -0700 (PDT) Date: Mon, 13 Apr 2020 08:34:53 -0700 From: Fangrui Song To: Jiaxun Yang Cc: "Maciej W. Rozycki" , linux-mips@vger.kernel.org, clang-built-linux@googlegroups.com, Nathan Chancellor , Thomas Bogendoerfer , Borislav Petkov , Kees Cook , Heiko Carstens , linux-kernel@vger.kernel.org Subject: Re: [PATCH v4] MIPS: Truncate link address into 32bit for 32bit kernel Message-ID: <20200413153453.zi4jvu3c4ul23e23@google.com> References: <20200413062651.3992652-1-jiaxun.yang@flygoat.com> <20200413153205.4ee52239@flygoat-x1e> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200413153205.4ee52239@flygoat-x1e> Sender: linux-mips-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 2020-04-13, Jiaxun Yang wrote: >On Mon, 13 Apr 2020 07:59:29 +0100 (BST) >"Maciej W. Rozycki" wrote: > >> On Mon, 13 Apr 2020, Jiaxun Yang wrote: >> >> > LLD failed to link vmlinux with 64bit load address for 32bit ELF >> > while bfd will strip 64bit address into 32bit silently. >> > To fix LLD build, we should truncate load address provided by >> > platform into 32bit for 32bit kernel. >> >> Reviewed-by: Maciej W. Rozycki >> >> > diff --git a/arch/mips/kernel/vmlinux.lds.S >> > b/arch/mips/kernel/vmlinux.lds.S index a5f00ec73ea6..5226cd8e4bee >> > 100644 --- a/arch/mips/kernel/vmlinux.lds.S >> > +++ b/arch/mips/kernel/vmlinux.lds.S >> > @@ -55,7 +55,7 @@ SECTIONS >> > /* . = 0xa800000000300000; */ >> > . = 0xffffffff80300000; >> > #endif >> > - . = VMLINUX_LOAD_ADDRESS; >> > + . = VMLINUX_LINK_ADDRESS; >> >> The CONFIG_BOOT_ELF64 cruft right above it looks interesting to me, >> never have ever been used. We have had the current arrangement since: > >It confused me either. >It's only used by SGI so probably it's time to rename it as >BOOT_SEG_ELF64. > >Wish someone could clarify what is it. > >Thanks. Agreed that -Ttext in arch/mips/boot/compressed/Makefile 100: cmd_zld = $(LD) $(KBUILD_LDFLAGS) -Ttext $(VMLINUZ_LOAD_ADDRESS) -T $< $(vmlinuzobjs-y) -o $@ and a few other places are brittle. They need to be replaced with Output Section Address: (https://sourceware.org/binutils/docs/ld/Output-Section-Address.html https://github.com/llvm/llvm-project/blob/master/lld/docs/ELF/linker_script.rst#output-section-address) -Ttext changes the address of .text . This can lead to the change of the address of the text segment (RX), but this is not guaranteed (many sections can be placed before .text and they are not affected). See https://reviews.llvm.org/D70468 "[ELF] Error if -Ttext-segment is specified" Reviewed-by: Fangrui Song >> >> commit 923ec3d20eef9e36456868b590873ce39f17fe71 >> Author: Ralf Baechle >> Date: Wed Nov 6 22:16:38 2002 +0000 >> >> Define load address in linker script instead of relying on the >> deprecated and notoriously unreliable option -Ttext. >> >> and previously `-Ttext' was used with this script anyway, though not >> very long, as the script was entirely ignored until: >> >> commit 7a782968041ffc4c2d89816238e2f8ea5cceddba >> Author: Ralf Baechle >> Date: Thu Oct 31 23:54:21 2002 +0000 >> >> Merge with Linux 2.5.36. >> >> Maciej > >-- >Jiaxun Yang