Re: [PATCH] x86/fpu: move FPU state into separate cache

[Dave Hansen]

On 03/29/2017 02:09 PM, Kees Cook wrote:
> They're adjacent already, which poses a problem for the struct layout
> randomization plugin, since adjacency may no longer be true (after
> layout randomization). This adjacency (or not) isn't really the
> problem: it's that FPU state size is only known at runtime. Another
> solution would be to have FPU state be a fixed size...

We don't want that.  It varies from a couple hundred bytes to ~3k on
newer CPUs.  We don't want to eat an extra 2.5k per task on the older
processors.