Re: [PATCH 00/11 v3] x86: load FPU registers on return to userland

[Rik van Riel]

On Thu, 2018-10-04 at 16:05 +0200, Sebastian Andrzej Siewior wrote:


> In v3 I dropped that decouple idea. I also learned that the wrpkru
> instruction is not privileged and so caching it in kernel does not
> work.

Wait, so any thread can bypass its memory protection
keys, even if there is a seccomp filter preventing
it from calling the PKRU syscalls?

Is that intended?

Is that simply a hardware limitation, or something
where we can set a flag somewhere to force tasks to
go through the kernel?

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