On Wed, Feb 08, 2017 at 11:55:41AM +0000, Ard Biesheuvel wrote:

To prevent unintended modifications to the kernel text (malicious or
otherwise) while running the EFI stub, describe the kernel image as
two separate sections: a .text section with read-execute permissions,
covering .text, .rodata and .init.text, and a .data section with
read-write permissions, covering .init.data, .data and .bss.

This relies on the firmware to actually take the section permission
flags into account, but this is something that is currently being
implemented in EDK2, which means we will likely start seeing it in
the wild between one and two years from now.

Signed-off-by: Ard Biesheuvel <redacted>

I understand that the stub needs to split the init text/data since
unlike the kernel it'll map those with separate permissions, but it
feels odd to do this specifically for the EFI stub.

Yould it perhaps make more sense to always use separate segments for
init/exit text/data, and also apply the permission split in the kernel?

With that, I don't think we'd need additional stub-specific linker
script changes.

Thanks,
Mark.