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

Borislav Petkov
2019-02-13T09:35:53Z

On Thu, Feb 07, 2019 at 12:49:42PM +0100, Sebastian Andrzej Siewior wrote:
> On 2019-01-30 12:55:07 [+0100], Borislav Petkov wrote:
> > 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.
>
> Added:
>
> Index: staging/arch/x86/include/asm/fpu/internal.h
> ===================================================================
> --- staging.orig/arch/x86/include/asm/fpu/internal.h
> +++ staging/arch/x86/include/asm/fpu/internal.h
> @@ -537,6 +537,12 @@ static inline void __fpregs_load_activat
> *
> * The FPU context is only stored/restore for user task and ->mm is used to
> * distinguish between kernel and user threads.
> + *
> + * If TIF_NEED_FPU_LOAD is cleared then CPU's FPU registers are holding the
> + * current content of current()'s FPU register state.

"current content of current" - that's a lot of c...

Make that

"... then the CPU's FPU registers are mirrored in the current thread's
FPU registers state."

> + * If TIF_NEED_FPU_LOAD is set then CPU's FPU registers may not hold current()'s
> + * FPU registers. It is required to load the register before returning to
^^^^^^^^

s/register/registers/ - plural.

Thx.

--
Regards/Gruss,
Boris.

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