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=-9.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C674EC2BC11 for ; Tue, 8 Sep 2020 20:17:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 80E8A208FE for ; Tue, 8 Sep 2020 20:17:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="qZ/9AznD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730721AbgIHURl (ORCPT ); Tue, 8 Sep 2020 16:17:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729057AbgIHURi (ORCPT ); Tue, 8 Sep 2020 16:17:38 -0400 Received: from mail-qk1-x743.google.com (mail-qk1-x743.google.com [IPv6:2607:f8b0:4864:20::743]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8AE5EC061573; Tue, 8 Sep 2020 13:17:37 -0700 (PDT) Received: by mail-qk1-x743.google.com with SMTP id g72so348805qke.8; Tue, 08 Sep 2020 13:17:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:date:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=/08OEII2Gc2davobAmINkHdHlTLoM3yBel115LZWEGE=; b=qZ/9AznDVXFtr6CrHuhiw4QW5HmClw8tl/kn16sP+vAL9BwyB1TalbAKldIgIIFtb+ 4gbcw6Ixl7WWm6+eR7AOeeEgNHRd9KO82LOanYAhZnktvDEwnWkiDthqJWrrSp8D42u4 fIeAiy4POw3wf4Z6SvhKEEye1aUrwOIWslhBv+79RaCXHWn4YpCcP2k1rJp/fR64lnQC 8jnqEJ5IzfX5q10Y72vrRW9J8/NnBj7zCdAZsoK7DHNMvg7HjynBh+r4iRBw+V66mCG0 KesRtoiYqBsl5xile5AfugcBIKBCC3vQzS/rH6rs/JmItACffhMLEWNQHzOwlPtwLyAt KhyA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:date:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=/08OEII2Gc2davobAmINkHdHlTLoM3yBel115LZWEGE=; b=K925NchmjXWEiCGzH/kNzYavYK/+3NvvHQbPDKJID+oSaUT+/F7KgHrJeQq6W4BUd3 HVUWnSZUpFirCvHtH6NXxK2lTqJGjxBCCyEd0vmtXN/MZPj+9JqZ5SUmtNXuEr3PAi7l QVig32ntP3fPbaJ8MZzx7i4Msq5VVP/kqO/bncdGSdDlu2rYTgAZup6YnMMwIHuRYRj0 NB71p+E7fxsbYAKUN9dePcukfKFUQqkHVS7UJixLzmnlGr1PB+7e/EhWxaNa+r163tp3 W1BfEXyKu4jLczdr/Sv8p4NB+h54CBFjccKqaITKNI6FYftKGc1a8/yNuszY6CcJNR4N nV5w== X-Gm-Message-State: AOAM531Bd7P55qEyfZpPCr0xrPOYptsEA+iNJgs4TwdAy+YLtD91YELP UZz7Cb72I157G9mxj1cT1n4= X-Google-Smtp-Source: ABdhPJwNSgWEhWS2D5NSJFniOHBOS9/EWNgGqZsCsA91Ij4q3VjCGMYQaXbuPxF07dtwVNjz7gPPBQ== X-Received: by 2002:a05:620a:955:: with SMTP id w21mr302081qkw.69.1599596256656; Tue, 08 Sep 2020 13:17:36 -0700 (PDT) Received: from rani.riverdale.lan ([2001:470:1f07:5f3::b55f]) by smtp.gmail.com with ESMTPSA id z6sm335661qkl.39.2020.09.08.13.17.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Sep 2020 13:17:35 -0700 (PDT) From: Arvind Sankar X-Google-Original-From: Arvind Sankar Date: Tue, 8 Sep 2020 16:17:34 -0400 To: Arvind Sankar Cc: Kees Cook , Ingo Molnar , Borislav Petkov , Catalin Marinas , Mark Rutland , Ard Biesheuvel , Peter Collingbourne , James Morse , 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 v7 4/5] x86/build: Warn on orphan section placement Message-ID: <20200908201734.GA87825@rani.riverdale.lan> References: <20200902025347.2504702-1-keescook@chromium.org> <20200902025347.2504702-5-keescook@chromium.org> <20200905224835.GA1500331@rani.riverdale.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200905224835.GA1500331@rani.riverdale.lan> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 05, 2020 at 06:48:35PM -0400, Arvind Sankar wrote: > On Tue, Sep 01, 2020 at 07:53:46PM -0700, Kees Cook wrote: > > We don't want to depend on the linker's orphan section placement > > heuristics as these can vary between linkers, and may change between > > versions. All sections need to be explicitly handled in the linker script. > > > > Now that all sections are explicitly handled, enable orphan section > > warnings. > > > > Signed-off-by: Kees Cook > > --- > > arch/x86/Makefile | 4 ++++ > > 1 file changed, 4 insertions(+) > > > > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > > index 4346ffb2e39f..154259f18b8b 100644 > > --- a/arch/x86/Makefile > > +++ b/arch/x86/Makefile > > @@ -209,6 +209,10 @@ ifdef CONFIG_X86_64 > > LDFLAGS_vmlinux += -z max-page-size=0x200000 > > endif > > > > +# We never want expected sections to be placed heuristically by the > > +# linker. All sections should be explicitly named in the linker script. > > +LDFLAGS_vmlinux += $(call ld-option, --orphan-handling=warn) > > + > > archscripts: scripts_basic > > $(Q)$(MAKE) $(build)=arch/x86/tools relocs > > > > -- > > 2.25.1 > > > > With LLVM=1 and GCOV_KERNEL/GCOV_PROFILE_ALL enabled, there are > .eh_frame sections created. I see that KASAN and KCSAN currently discard > them. Does GCOV actually need them or should it also discard? > > Thanks. Also, with LLD 10.0.1 which is going to be the minimum supported version, the relocation sections etc still generate warnings. ld.lld: warning: arch/x86/video/built-in.a(fbdev.o):(.rela.orc_unwind_ip) is being placed in '.rela.orc_unwind_ip' ld.lld: warning: .tmp_vmlinux.kallsyms2.o:(.rela.rodata) is being placed in '.rela.rodata' ld.lld: warning: :(.bss.rel.ro) is being placed in '.bss.rel.ro' ld.lld: warning: :(.eh_frame) is being placed in '.eh_frame' ld.lld: warning: :(.symtab_shndx) is being placed in '.symtab_shndx'