Re: [RFC] x86/mm/KASLR: Remap GDTs at fixed location

From: Thomas Garnier
Date: Thu Jan 05 2017 - 14:13:17 EST


On Thu, Jan 5, 2017 at 10:58 AM, Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> wrote:
> On 1/5/2017 9:54 AM, Thomas Garnier wrote:
>
>>
>> That's my goal too. I started by doing a RO remap and got couple
>> problems with hibernation. I can try again for the next iteration or
>> delay it for another patch. I also need to look at KVM GDT usage, I am
>> not familiar with it yet.
>
>
> don't we write to the GDT as part of the TLS segment stuff for glibc ?
>

Not sure which glibc feature it is.

In this design, you can write to the GDT per-cpu variable that will
remain read-write. You just need to make the remapping writeable when
we load task registers (ltr) then the processor use the current GDT
address. At least that the case I know, I might find more through
testing.

--
Thomas