Re: [PATCH] x86 : Add NX protection for kernel data on 64 bit

[H. Peter Anvin]

On 03/13/2011 11:37 AM, matthieu castet wrote:
> Cpu hotplug code read data in head_64.S (phys_base) before enabling NX, so when
> we enable NX on data, an triple fault happen because a reserved bit is set.
> It was fixed by allocating dedicated page table for ident mapping in trampoline.
> Now data can be protected by NX.
> 
> The Low kernel Mapping is also set to NX.
> 
> Finaly we preserve large page mapping by applying nx in free_init_pages only 
> when we switch to NX mode

The right way to do this is to have initial_page_table and keep it
around, just as we already do on 32 bits... yet another thing that can
be merged instead of coming up with a separate solution.

	-hpa
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