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    SubjectRe: [PATCH 15/22] x86/entry: Add TIF_NEED_FPU_LOAD
    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.
    + * 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
    + * userland or using the content otherwise.
    */
    static inline void
    switch_fpu_prepare(struct fpu *old_fpu, int cpu)
    Sebastian

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