linux-kernel - Re: [PATCH v3 4/7] x86/boot: Add .text.* to setup.ld

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Message-ID: <202006290854.CCFE11C@keescook>
Date:   Mon, 29 Jun 2020 08:55:53 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Fangrui Song <maskray@...gle.com>,
        Dmitry Golovin <dima@...ovin.in>,
        clang-built-linux@...glegroups.com,
        Ard Biesheuvel <ardb@...nel.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Daniel Kiper <daniel.kiper@...cle.com>,
        Sedat Dilek <sedat.dilek@...il.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        "H . J . Lu" <hjl@...rceware.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 4/7] x86/boot: Add .text.* to setup.ld

On Mon, Jun 29, 2020 at 10:09:25AM -0400, Arvind Sankar wrote:
> gcc puts the main function into .text.startup when compiled with -Os (or
> -O2). This results in arch/x86/boot/main.c having a .text.startup
> section which is currently not included explicitly in the linker script
> setup.ld in the same directory.
> 
> The BFD linker places this orphan section immediately after .text, so
> this still works. However, LLD git, since [1], is choosing to place it
> immediately after the .bstext section instead (this is the first code
> section). This plays havoc with the section layout that setup.elf
> requires to create the setup header, for eg on 64-bit:

Eep! I guess this was a linking case I missed for adding
--orphan-handling=warn to my orphan handling series. (I will add that.)

Reviewed-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook