Messages in this thread | | | From | Thomas Garnier <> | Date | Thu, 5 Jan 2017 15:16:05 -0800 | Subject | Re: [RFC] x86/mm/KASLR: Remap GDTs at fixed location |
| |
On Thu, Jan 5, 2017 at 3:05 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > On Thu, Jan 5, 2017 at 12:18 PM, Andy Lutomirski <luto@kernel.org> wrote: >> >> Hmm. I bet that if we preset the accessed bits in all the segments >> then we don't need it to be writable in general. > > I'm not sure that this is architecturally safe. > > IIRC, we do mark the IDT read-only - but that one we started doing due > to the f00f bug, so we knew it was ok. I'm not sure you can do the > same with the GDT/LDT. >
I started testing a variant that make the GDT remapping read-only by default and writeable only for LTR. Everything works fine, even hibernation. I need to do more testing though on different architectures.
To be on the safe side, I could separate the read-only part in a separate patch so we can easily remove it if extended testing show something.
> Linus
-- Thomas
| |