Re: [PATCH v8 0/3] x86/boot/KASLR: Parse ACPI table and limit kaslr in immovable memory

Baoquan He
2018-10-10T09:21:17Z

On 10/10/18 at 05:12pm, Chao Fan wrote:
> On Wed, Oct 10, 2018 at 05:06:20PM +0800, Baoquan He wrote:
> >Hi Boris,
> >
> >On 10/10/18 at 10:59am, Borislav Petkov wrote:
> >> ... and we just picked up
> >>
> >> https://lkml.kernel.org/r/20181001140843.26137-1-msys.mizuma@gmail.com
> >>
> >> and without having looked at the rest of your stuff, if people accept
> >> your solution, we don't need the silly parameter anymore, right?
> >>
> >> Which means, we should not rush the whole thing yet until the whole
> >> KASLR vs movable memory gets solved properly.
> >
> >Masa's patches solves the problem in memory region KASLR which later hot
> >added memory may be big than the default padding 10 TB.
> >
> >Chao's patches is trying to fix a conflict between 'movable_node' and
> >kernel text KASLR. If 'movable_node' specified, we rely on SRAT to get
> >which memory region is movable or immovable, and movable region can be
> >hot removed. But if kernel is randomized into movable memory, it can't
> >be hot removed any more, this is a regression after KASLR introduced.
> >So this is a different issue than Masa's.
>
> Yes, they are two issues.
> But if we can get more memory information by the function in
> the new file acpi.c, semms it's helfpul to Masa's issue.

Hmm, reading SRAT three times during x86 kernel boot? Maybe we try this
after the function has run a time and proved very stable?

Thanks
Baoquan