linux-kernel - Re: [PATCH v2 3/3] x86/boot/compressed: get rid of GOT fixup code

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Message-ID: <CAMj1kXH6ekEbY9TVT+_3NmrGVdGO0yUVx6hvtu4Z-4+AMT0+WQ@mail.gmail.com>
Date:   Sun, 24 May 2020 10:42:18 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Arvind Sankar <nivedita@...m.mit.edu>
Cc:     linux-efi <linux-efi@...r.kernel.org>, X86 ML <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2 3/3] x86/boot/compressed: get rid of GOT fixup code

On Sat, 23 May 2020 at 17:18, Arvind Sankar <nivedita@...m.mit.edu> wrote:
>
> On Sat, May 23, 2020 at 02:00:21PM +0200, Ard Biesheuvel wrote:
> > In a previous patch, we have eliminated GOT entries from the decompressor
> > binary and added an assertion that the .got section is empty. This means
> > that the GOT fixup routines that exist in both the 32-bit and 64-bit
> > startup routines have become dead code, and can be removed.
> >
> > Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
> > diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
> > index 60a99dfb9d72..d91fdda51aa8 100644
> > --- a/arch/x86/boot/compressed/vmlinux.lds.S
> > +++ b/arch/x86/boot/compressed/vmlinux.lds.S
> > @@ -43,9 +43,7 @@ SECTIONS
> >               _erodata = . ;
> >       }
> >       .got : {
> > -             _got = .;
> >               KEEP(*(.got))
> > -             _egot = .;
> >       }
> >       .got.plt : {
> >               KEEP(*(.got.plt))
> > --
> > 2.20.1
> >
>
> I think you can get rid of both the KEEP's here as well?

Yeah, they seem fairly pointless to me to begin with, given that these
contents are created by the linker on the fly, rather than passed
through from the input objects.

I'll drop them.