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Date: Fri, 10 Feb 2017 10:11:52 +0000
From: Mark Rutland <mark.rutland@....com>
To: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: linux-efi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
leif.lindholm@...aro.org, catalin.marinas@....com,
linux@...linux.org.uk, kernel-hardening@...ts.openwall.com,
labbott@...oraproject.org
Subject: Re: [PATCH v2 04/14] arm64: efi: clean up Image header after PE
header has been split off
On Wed, Feb 08, 2017 at 11:55:37AM +0000, Ard Biesheuvel wrote:
> After having split off the PE header, clean up the bits that remain:
> use .long consistently, merge two adjacent #ifdef CONFIG_EFI blocks,
> fix the offset of the PE header pointer and remove the redundant .align
> that follows it.
>
> Also, since we will be eliminating all open coded constants from the
> EFI header in subsequent patches, let's replace the open coded "ARM\x64"
> magic number with its .ascii equivalent.
>
> No changes to the resulting binary image are intended.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> ---
> arch/arm64/kernel/head.S | 17 ++++++++---------
> 1 file changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index f779a7483736..aa8f6cd8c33f 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -91,20 +91,19 @@ _head:
> .quad 0 // reserved
> .quad 0 // reserved
> .quad 0 // reserved
> - .byte 0x41 // Magic number, "ARM\x64"
> - .byte 0x52
> - .byte 0x4d
> - .byte 0x64
> + .ascii "ARM\x64" // Magic number
> #ifdef CONFIG_EFI
> + /*
> + * PE/COFF requires the offset to the PE header
> + * to be stored at offset 0x3c into the file.
> + */
> + .org _head + 0x3c
> .long pe_header - _head // Offset to the PE header.
Do we really need the .org? We expect all the other fields to stay in
place without one, and it seems odd to special-case the PE header.
Otherwise, this looks good to me.
Thanks,
Mark.
> -#else
> - .word 0 // reserved
> -#endif
>
> -#ifdef CONFIG_EFI
> - .align 3
> pe_header:
> __EFI_PE_HEADER
> +#else
> + .long 0 // reserved
> #endif
>
> __INIT
> --
> 2.7.4
>
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