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=-14.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_IN_DEF_DKIM_WL autolearn=unavailable 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 94F01C433DF for ; Wed, 24 Jun 2020 16:16:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5767520738 for ; Wed, 24 Jun 2020 16:16:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="IOKX5uP5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404838AbgFXQQv (ORCPT ); Wed, 24 Jun 2020 12:16:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404760AbgFXQQr (ORCPT ); Wed, 24 Jun 2020 12:16:47 -0400 Received: from mail-pl1-x643.google.com (mail-pl1-x643.google.com [IPv6:2607:f8b0:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9DEFCC061573 for ; Wed, 24 Jun 2020 09:16:47 -0700 (PDT) Received: by mail-pl1-x643.google.com with SMTP id y18so1242097plr.4 for ; Wed, 24 Jun 2020 09:16:47 -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=r9Atz1n5S97FsyRtwbW9FxEwVR3HptLSj7YkFtdgBWc=; b=IOKX5uP5HrCSDaBldb1Tlqjq7QjS/iWV7iYPBJGBjm5MBfZlGZ65fHIb7gwqwcoeRw dpXx4RbkMXKmlmUkJyMmOhKjGP7uq2faKSrJkx0pPbJOJB7HDj5gJYJ2qr85eHA/cnXV H6UkqiZT7Hf4A7Y6EJAKS9VnW6TG4YJJIJmC+zN1+gKqnpwjbbJGFpXjQv5PDJQkvtpY D/il9Ds6lNa0aRabxw+vMLX7xAiBD/HhgWYaeid2aqPseFEPjLtTY//si6OJ/tdrxJqy ei45oSHSPuORVmZon0PcThpNgkP0FKv3aL/MUReCE1NqPG/qnNGcmVu2OID8z6Gczdpa L/Ew== 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=r9Atz1n5S97FsyRtwbW9FxEwVR3HptLSj7YkFtdgBWc=; b=mf+g9uG1hjO/e2gl7kt8w+Rrzha+F+CvMThIW86D7hTEhAadCqiaaRzGog3eBx71os TcItUfoPBZanpNmPFPS0uNtMQdx5+yJphmRzAawTmBjtNDYhFkHUIdUVvl9r+L50BpgS Ep5rc+Ctp4hM8BMZFrGjYmODb28rE0TaOj+JiPJBrIUt5SQ6M7Fk5gsiyAcaUH4U3h2f Qp9YCn2j9C3WxfHUmw9L2VXxEFjfdBPBokZeWY5h2hOIZ+OrrzElDYdR5pw6ic3rE5HH qPhzyFDC9UDX/q2AOMZSGzfcIhe/klFqhPqf3meWB3gNt1GfUGxHfhWSQLhnPlGxNZvJ s+nQ== X-Gm-Message-State: AOAM532dJO2mOzyLD5foo/v65B64V95fFtoewT4s/VcTVu8SjqiV3fRI InrtKrG17TVi+chV3MDfpzKFPQ== X-Google-Smtp-Source: ABdhPJzR5oxdlp9qxvLSBQa9QdrzRcyjkIYkFPOJwAujW1umQ1cg0Dv9Hmvl7bclAIhrUSrRff3SUA== X-Received: by 2002:a17:90a:7c4e:: with SMTP id e14mr29364901pjl.175.1593015406860; Wed, 24 Jun 2020 09:16:46 -0700 (PDT) Received: from google.com ([2620:15c:2ce:0:9efe:9f1:9267:2b27]) by smtp.gmail.com with ESMTPSA id oc6sm6480133pjb.43.2020.06.24.09.16.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2020 09:16:46 -0700 (PDT) Date: Wed, 24 Jun 2020 09:16:43 -0700 From: Fangrui Song To: Arvind Sankar Cc: Kees Cook , Will Deacon , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Peter Collingbourne , James Morse , Borislav Petkov , Thomas Gleixner , Ingo Molnar , Russell King , Masahiro Yamada , Nick Desaulniers , Nathan Chancellor , Arnd Bergmann , x86@kernel.org, clang-built-linux@googlegroups.com, linux-arch@vger.kernel.org, linux-efi@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 2/9] vmlinux.lds.h: Add .symtab, .strtab, and .shstrtab to STABS_DEBUG Message-ID: <20200624161643.73x6navnwryckuit@google.com> References: <20200624014940.1204448-1-keescook@chromium.org> <20200624014940.1204448-3-keescook@chromium.org> <20200624153930.GA1337895@rani.riverdale.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20200624153930.GA1337895@rani.riverdale.lan> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-06-24, Arvind Sankar wrote: >On Tue, Jun 23, 2020 at 06:49:33PM -0700, Kees Cook wrote: >> When linking vmlinux with LLD, the synthetic sections .symtab, .strtab, >> and .shstrtab are listed as orphaned. Add them to the STABS_DEBUG section >> so there will be no warnings when --orphan-handling=warn is used more >> widely. (They are added above comment as it is the more common > >Nit 1: is "after .comment" better than "above comment"? It's above in the >sense of higher file offset, but it's below in readelf output. I mean this order:) .comment .symtab .shstrtab .strtab This is the case in the absence of a linker script if at least one object file has .comment (mostly for GCC/clang version information) or the linker is LLD which adds a .comment >Nit 2: These aren't actually debugging sections, no? Is it better to add >a new macro for it, and is there any plan to stop LLD from warning about >them? https://reviews.llvm.org/D75149 "[ELF] --orphan-handling=: don't warn/error for unused synthesized sections" described that .symtab .shstrtab .strtab are different in GNU ld. Since many other GNU ld synthesized sections (.rela.dyn .plt ...) can be renamed or dropped via output section descriptions, I don't understand why the 3 sections can't be customized. I created a feature request: https://sourceware.org/bugzilla/show_bug.cgi?id=26168 (If this is supported, it is a consistent behavior to warn for orphan .symtab/.strtab/.shstrtab There may be 50% chance that the maintainer decides that "LLD diverges" I would disagree: there is no fundamental problems with .symtab/.strtab/.shstrtab which make them special in output section descriptions or orphan handling.) >> order[1].) >> >> ld.lld: warning: :(.symtab) is being placed in '.symtab' >> ld.lld: warning: :(.shstrtab) is being placed in '.shstrtab' >> ld.lld: warning: :(.strtab) is being placed in '.strtab' >> >> [1] https://lore.kernel.org/lkml/20200622224928.o2a7jkq33guxfci4@google.com/ >> >> Reported-by: Fangrui Song >> Reviewed-by: Fangrui Song >> Signed-off-by: Kees Cook >> --- >> include/asm-generic/vmlinux.lds.h | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h >> index 1248a206be8d..8e71757f485b 100644 >> --- a/include/asm-generic/vmlinux.lds.h >> +++ b/include/asm-generic/vmlinux.lds.h >> @@ -792,7 +792,10 @@ >> .stab.exclstr 0 : { *(.stab.exclstr) } \ >> .stab.index 0 : { *(.stab.index) } \ >> .stab.indexstr 0 : { *(.stab.indexstr) } \ >> - .comment 0 : { *(.comment) } >> + .comment 0 : { *(.comment) } \ >> + .symtab 0 : { *(.symtab) } \ >> + .strtab 0 : { *(.strtab) } \ >> + .shstrtab 0 : { *(.shstrtab) } >> >> #ifdef CONFIG_GENERIC_BUG >> #define BUG_TABLE \ >> -- >> 2.25.1 >>