Re: [PATCH] arm64/efi: set PE/COFF file alignment to 512 bytes

Roy Franz
2014-10-10T17:07:48Z

On Fri, Oct 10, 2014 at 9:58 AM, Ard Biesheuvel
<ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> wrote:
> Change our PE/COFF header to use the minimum file alignment of
> 512 bytes (0x200), as mandated by the PE/COFF spec v8.3
>
> Also update the linker script so that the Image file itself is also a
> round multiple of FileAlignment.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---

Signed-off-by: Roy Franz <roy.franz-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

>
> Another one from the PE/COFF rabbit hole. I will follow up next week and repost
> as a coherent series, once I have collected all the feedback.
>
> arch/arm64/kernel/head.S | 2 +-
> arch/arm64/kernel/vmlinux.lds.S | 17 +++++++++++++++++
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
> index ba715ce3f7f1..e7e83b3128fd 100644
> --- a/arch/arm64/kernel/head.S
> +++ b/arch/arm64/kernel/head.S
> @@ -162,7 +162,7 @@ optional_header:
> extra_header_fields:
> .quad 0 // ImageBase
> .long 0x1000 // SectionAlignment
> - .long 0x8 // FileAlignment
> + .long PECOFF_FILE_ALIGNMENT // FileAlignment
> .short 0 // MajorOperatingSystemVersion
> .short 0 // MinorOperatingSystemVersion
> .short 0 // MajorImageVersion
> diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S
> index edf8715ba39b..4596f46d0244 100644
> --- a/arch/arm64/kernel/vmlinux.lds.S
> +++ b/arch/arm64/kernel/vmlinux.lds.S
> @@ -32,6 +32,22 @@ jiffies = jiffies_64;
> *(.hyp.text) \
> VMLINUX_SYMBOL(__hyp_text_end) = .;
>
> +/*
> + * The size of the PE/COFF section that covers the kernel image, which
> + * runs from stext to _edata, must be a round multiple of the PE/COFF
> + * FileAlignment, which we set to its minimum value of 0x200. 'stext'
> + * itself is 4 KB aligned, so padding out _edata to a 0x200 aligned
> + * boundary should be sufficient.
> + */
> +PECOFF_FILE_ALIGNMENT = 0x200;
> +
> +#ifdef CONFIG_EFI
> +#define PECOFF_EDATA_PADDING \
> + .pecoff_edata_padding : { BYTE(0); . = ALIGN(PECOFF_FILE_ALIGNMENT); }
> +#else
> +#define PECOFF_EDATA_PADDING
> +#endif
> +
> SECTIONS
> {
> /*
> @@ -103,6 +119,7 @@ SECTIONS
> _data = .;
> _sdata = .;
> RW_DATA_SECTION(64, PAGE_SIZE, THREAD_SIZE)
> + PECOFF_EDATA_PADDING
> _edata = .;
>
> BSS_SECTION(0, 0, 0)
> --
> 1.8.3.2
>