linux-kernel - Re: [PATCH v5 0/7] x86/boot: Remove run-time relocations from compressed kernel

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Message-ID: <20200717134654.GA3187880@rani.riverdale.lan>
Date:   Fri, 17 Jul 2020 09:46:54 -0400
From:   Arvind Sankar <nivedita@...m.mit.edu>
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>,
        Sedat Dilek <sedat.dilek@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        "H . J . Lu" <hjl@...rceware.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/7] x86/boot: Remove run-time relocations from
 compressed kernel

On Tue, Jul 14, 2020 at 08:41:26PM -0400, Arvind Sankar wrote:
> The compressed kernel currently contains bogus run-time relocations in
> the startup code in head_{32,64}.S, which are generated by the linker,
> but must not actually be processed at run-time.
> 
> This generates warnings when linking with the BFD linker, and errors
> with LLD, which defaults to erroring on run-time relocations in read-only
> sections. It also requires the -z noreloc-overflow hack for the 64-bit
> kernel, which prevents us from linking it as -pie on an older BFD linker
> (<= 2.26) or on LLD, because the locations that are to be apparently
> relocated are only 32-bits in size and so cannot really have
> R_X86_64_RELATIVE relocations.
> 
> This series aims to get rid of these relocations. I've build- and
> boot-tested with combinations of clang/gcc-10 with lld/bfd-2.34, and
> gcc-4.9.0 with bfd-2.24, skipping clang on 32-bit because it currently
> has other issues [0].
> 

Hi Thomas, Ingo, Borislav, would you be able to take a look over this
series in time for 5.9?

Thanks.