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Re: [Xen-devel] xen/link: Move .data.rel.ro sections into .rodata for final link

On 30/07/17 07:16, Jan Beulich wrote:
>>>> David Woodhouse <dwmw2@xxxxxxxxxxxxx> 07/20/17 5:22 PM >>>
>> This includes stuff lke the hypercall tables which we really want
>> to be read-only. And they were going into .data.read-mostly.
> Yes, we'd like them to be read-only, but what if EFI properly assigned r/o
> permissions to the .rodata section when loading xen.efi? We'd then be
> unable to apply relocations when switching from 1:1 to virtual mappings
> (see efi_arch_relocate_image()).

Ah yes.  I'd overlooked that point when considering the ramifications of
this change.

efi_arch_relocate_image() should probably do the same as what we do with
livepatching, and temporarily clear CR0.WP for the duration of the patching.


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