Re: [PATCH] x86/efi: Store upper bits of command line buffer address in ext_cmd_line_ptr

From: Matt Fleming
Date: Fri Apr 17 2015 - 10:43:12 EST


On Wed, 15 Apr, at 04:32:24PM, Roy Franz wrote:
> Until now, the EFI stub was only setting the 32 bit cmd_line_ptr in
> the setup_header structure, so on 64 bit platforms this could be truncated.
> This patch adds setting the upper bits of the buffer address in
> ext_cmd_line_ptr. This case was likely never hit, as the allocation
> for this buffer is done at the lowest available address. Only
> x86_64 kernels have this problem, as the 1-1 mapping mandated
> by EFI ensures that all memory is 32 bit addressable on 32 bit
> platforms. The EFI stub does not support mixed mode, so the
> 32 bit kernel on 64 bit firmware case does not need to be handled.
>
> Signed-off-by: Roy Franz <roy.franz@xxxxxxxxxx>
> ---
> This is a follow-up to "x86_64/efi: enforce 32 bit address for command line buffer",
> which had the wrong fix to the truncation of address.
>
> arch/x86/boot/compressed/eboot.c | 2 ++
> 1 file changed, 2 insertions(+)

Looks good to me Roy, thanks applied!

--
Matt Fleming, Intel Open Source Technology Center
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