linux-kernel - Re: [PATCH 1/2] x86/boot/compressed/64: Remove .bss/.pgtable from bzImage

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Message-ID: <20200406172102.GF2520@zn.tnic>
Date:   Mon, 6 Apr 2020 19:21:02 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ard Biesheuvel <ardb@...nel.org>,
        Arvind Sankar <nivedita@...m.mit.edu>
Cc:     Sergey Shatunov <me@...k.pw>, hpa@...or.com,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        mingo@...hat.com, Thomas Gleixner <tglx@...utronix.de>,
        x86@...nel.org, linux-efi <linux-efi@...r.kernel.org>,
        initramfs@...r.kernel.org,
        Donovan Tremura <neurognostic@...tonmail.ch>,
        Harald Hoyer <harald@...er.xyz>
Subject: Re: [PATCH 1/2] x86/boot/compressed/64: Remove .bss/.pgtable from
 bzImage

On Mon, Apr 06, 2020 at 03:29:18PM +0200, Ard Biesheuvel wrote:
> > What do you think of the other problem -- that's actually worse to fix,
> > as it won't just be when kaslr is disabled, the startup_64 code will do
> > relocation to the end of init_size and clobber the initrd before getting
> > to the kaslr code, so it will break as soon as the firmware loads the
> > "unified kernel image" at a 2Mb-aligned address. The only thing I can
> > think of is to just unconditionally call efi_relocate_kernel if we were
> > entered via handover_entry?
> >
> 
> Yes, that seems to be the most robust approach.

The commit in question is this one:

d5cdf4cfeac9 ("efi/x86: Don't relocate the kernel unless necessary")

I presume?

I'm guessing it can simply be reverted as it doesn't fix a bug but it is
just an optimization... provided I'm not missing something, of course.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette