linux-kernel - Re: [PATCH v2 00/15] x86/boot: Rework PE header generation

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Date:   Fri, 15 Sep 2023 15:21:36 +0200
From:   Ard Biesheuvel <ardb@...gle.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ard Biesheuvel <ardb@...nel.org>,
        Evgeniy Baskov <baskov@...ras.ru>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Jones <pjones@...hat.com>,
        Matthew Garrett <mjg59@...f.ucam.org>,
        Gerd Hoffmann <kraxel@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2 00/15] x86/boot: Rework PE header generation

On Fri, Sep 15, 2023 at 1:31 PM Ingo Molnar <mingo@...nel.org> wrote:
>
>
> * Ingo Molnar <mingo@...nel.org> wrote:
>
> > > Ard Biesheuvel (15):
> > >   x86/efi: Drop EFI stub .bss from .data section
> > >   x86/efi: Disregard setup header of loaded image
> > >   x86/efi: Drop alignment flags from PE section headers
> > >   x86/boot: Remove the 'bugger off' message
> > >   x86/boot: Omit compression buffer from PE/COFF image memory footprint
> > >   x86/boot: Drop redundant code setting the root device
> > >   x86/boot: Grab kernel_info offset from zoffset header directly
> > >   x86/boot: Drop references to startup_64
> >
> > I've applied these first 8 patches to tip:x86/boot with minor edits.

Thanks.

> > (Please preserve existing comment capitalization conventions ...)
> >

Ack

> > >   x86/boot: Set EFI handover offset directly in header asm
> > >   x86/boot: Define setup size in linker script
> > >   x86/boot: Derive file size from _edata symbol
> > >   x86/boot: Construct PE/COFF .text section from assembler
> > >   x86/boot: Drop PE/COFF .reloc section
> > >   x86/boot: Split off PE/COFF .data section
> > >   x86/boot: Increase section and file alignment to 4k/512
> >
> > The rest conflicted with recent upstream changes, and I suppose it's
> > prudent to test these changes bit by bit anyway.
>

Agreed. So you mean this conflicts with other stuff queued up in -tip
already, right?

> So, the first 8 patches broke the x86-64-defconfig-ish Qemu bzImage bootup,
> due to the 8th patch:
>
>   988b52b207a9fe74c3699bda8c2256714926b94b is the first bad commit
>   commit 988b52b207a9fe74c3699bda8c2256714926b94b
>   Author: Ard Biesheuvel <ardb@...nel.org>
>   Date:   Tue Sep 12 09:01:01 2023 +0000
>
>       x86/boot: Define setup size in linker script
>
> I've removed it for now - but this side effect was not expected.
>

No, definitely not expected. I tested various combinations of i386 /
x86_64 built with GCC / Clang doing EFI or BIOS boot.

I'll rebase the remaining stuff onto -tip and see if I can reproduce this.