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SubjectRe: [PATCH 1/2] x86/mm: Move LDT remap out of KASLR region on 5-level paging
On Wed, Oct 24, 2018 at 04:54:47AM -0700, Matthew Wilcox wrote:
> On Tue, Oct 23, 2018 at 07:31:56PM +0300, Kirill A. Shutemov wrote:
> > -ffff880000000000 - ffffc7ffffffffff (=64 TB) direct mapping of all phys. memory
> > +ffff888000000000 - ffff887fffffffff (=39 bits) LDT remap for PTI
>
> I'm a little bit cross-eyed at this point, but I think the above '888'
> should be '880'.
>
> > @@ -14,7 +15,6 @@ ffffec0000000000 - fffffbffffffffff (=44 bits) kasan shadow memory (16TB)
> > ... unused hole ...
> > vaddr_end for KASLR
> > fffffe0000000000 - fffffe7fffffffff (=39 bits) cpu_entry_area mapping
> > -fffffe8000000000 - fffffeffffffffff (=39 bits) LDT remap for PTI
>
> ... and the line above this one should be adjusted to finish at
> fffffeffffffffff (also it's now 40 bits). Or should there be something
> else here?
>
> > ffffff0000000000 - ffffff7fffffffff (=39 bits) %esp fixup stacks
> > ... unused hole ...
> > ffffffef00000000 - fffffffeffffffff (=64 GB) EFI region mapping space
> > @@ -30,8 +30,8 @@ Virtual memory map with 5 level page tables:
> > 0000000000000000 - 00ffffffffffffff (=56 bits) user space, different per mm
> > hole caused by [56:63] sign extension
> > ff00000000000000 - ff0fffffffffffff (=52 bits) guard hole, reserved for hypervisor
> > -ff10000000000000 - ff8fffffffffffff (=55 bits) direct mapping of all phys. memory
> > -ff90000000000000 - ff9fffffffffffff (=52 bits) LDT remap for PTI
> > +ff10000000000000 - ff10ffffffffffff (=48 bits) LDT remap for PTI
> > +ff11000000000000 - ff90ffffffffffff (=55 bits) direct mapping of all phys. memory
>
> What's at ff910..0 to ff9f..f ?
>
> Is there any way we can generate this part of this file to prevent human
> error from creeping in over time? ;-)

In current Linus' tree this part of the documentation was re-written. I've
rebased to it and rewrote the documenation for the change.

I believe I've fixed all mistakes you've noticied. Please check out v2. I
will post it soon.

--
Kirill A. Shutemov

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