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    Subject[PATCH 09/22] x86/fpu: Add (__)make_fpregs_active helpers
    Date
    From: Rik van Riel <riel@surriel.com>

    Add helper function that ensures the floating point registers for
    the current task are active. Use with preemption disabled.

    Signed-off-by: Rik van Riel <riel@surriel.com>
    Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
    ---
    arch/x86/include/asm/fpu/api.h | 11 +++++++++++
    arch/x86/include/asm/fpu/internal.h | 19 +++++++++++--------
    2 files changed, 22 insertions(+), 8 deletions(-)

    diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
    index b56d504af6545..73e684160f354 100644
    --- a/arch/x86/include/asm/fpu/api.h
    +++ b/arch/x86/include/asm/fpu/api.h
    @@ -10,6 +10,7 @@

    #ifndef _ASM_X86_FPU_API_H
    #define _ASM_X86_FPU_API_H
    +#include <linux/preempt.h>

    /*
    * Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It
    @@ -22,6 +23,16 @@ extern void kernel_fpu_begin(void);
    extern void kernel_fpu_end(void);
    extern bool irq_fpu_usable(void);

    +static inline void fpregs_lock(void)
    +{
    + preempt_disable();
    +}
    +
    +static inline void fpregs_unlock(void)
    +{
    + preempt_enable();
    +}
    +
    /*
    * Query the presence of one or more xfeatures. Works on any legacy CPU as well.
    *
    diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
    index 96835d04e9343..67e4805bccb6f 100644
    --- a/arch/x86/include/asm/fpu/internal.h
    +++ b/arch/x86/include/asm/fpu/internal.h
    @@ -515,6 +515,15 @@ static inline void fpregs_activate(struct fpu *fpu)
    trace_x86_fpu_regs_activated(fpu);
    }

    +static inline void __fpregs_load_activate(struct fpu *fpu, int cpu)
    +{
    + if (!fpregs_state_valid(fpu, cpu)) {
    + if (current->mm)
    + copy_kernel_to_fpregs(&fpu->state);
    + fpregs_activate(fpu);
    + }
    +}
    +
    /*
    * FPU state switching for scheduling.
    *
    @@ -553,14 +562,8 @@ switch_fpu_prepare(struct fpu *old_fpu, int cpu)
    */
    static inline void switch_fpu_finish(struct fpu *new_fpu, int cpu)
    {
    - if (static_cpu_has(X86_FEATURE_FPU)) {
    - if (!fpregs_state_valid(new_fpu, cpu)) {
    - if (current->mm)
    - copy_kernel_to_fpregs(&new_fpu->state);
    - }
    -
    - fpregs_activate(new_fpu);
    - }
    + if (static_cpu_has(X86_FEATURE_FPU))
    + __fpregs_load_activate(new_fpu, cpu);
    }

    /*
    --
    2.20.1
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