Re: [PATCH 15/22] x86/entry: Add TIF_NEED_FPU_LOAD

Borislav Petkov
2019-01-30T11:55:18Z

On Wed, Jan 09, 2019 at 12:47:37PM +0100, Sebastian Andrzej Siewior wrote:
> Add TIF_NEED_FPU_LOAD. This is reserved for loading the FPU registers
> before returning to userland. This flag must not be set for systems
> without a FPU.
> If this flag is cleared, the CPU's FPU register hold the current content
> of current()'s FPU register. The in-memory copy (union fpregs_state) is
> not valid.
> If this flag is set, then all of CPU's FPU register may hold a random
> value (except for PKRU) and it is required to load the content of the
> FPU register on return to userland.

This definitely needs to be written somewhere in

arch/x86/include/asm/fpu/internal.h

or where we decide to put the FPU handling rules.

--
Regards/Gruss,
Boris.

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