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    Subject[PATCH 089/208] x86/fpu: Rename fpu->has_fpu to fpu->fpregs_active
    Date
    So the current code uses fpu->has_cpu to determine whether a given
    user FPU context is actively loaded into the FPU's registers [*] and
    that those registers represent the task's current FPU state.

    But this term is not unambiguous: especially the distinction between
    fpu->has_fpu, PF_USED_MATH and fpu_fpregs_owner_ctx is not clear.

    Increase clarity by unambigously signalling that it's about
    hardware registers being active right now, by renaming it to
    fpu->fpregs_active.

    ( In later patches we'll use more of the 'fpregs' naming, which will
    make it easier to grep for as well. )

    [*] There's the kernel_fpu_begin()/end() primitive that also
    activates FPU hw registers as well and uses them, without
    touching the fpu->fpregs_active flag.

    Reviewed-by: Borislav Petkov <bp@alien8.de>
    Cc: Andy Lutomirski <luto@amacapital.net>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Cc: H. Peter Anvin <hpa@zytor.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Oleg Nesterov <oleg@redhat.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    ---
    arch/x86/include/asm/fpu/api.h | 2 +-
    arch/x86/include/asm/fpu/internal.h | 12 ++++++------
    arch/x86/include/asm/fpu/types.h | 2 +-
    arch/x86/kernel/fpu/core.c | 10 +++++-----
    4 files changed, 13 insertions(+), 13 deletions(-)

    diff --git a/arch/x86/include/asm/fpu/api.h b/arch/x86/include/asm/fpu/api.h
    index 5bdde8ca87bc..4ca745c0d92e 100644
    --- a/arch/x86/include/asm/fpu/api.h
    +++ b/arch/x86/include/asm/fpu/api.h
    @@ -96,7 +96,7 @@ static inline void irq_ts_restore(int TS_state)
    */
    static inline int user_has_fpu(void)
    {
    - return current->thread.fpu.has_fpu;
    + return current->thread.fpu.fpregs_active;
    }

    extern void fpu__save(struct fpu *fpu);
    diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
    index 6eea81c068fb..b546ec816fd6 100644
    --- a/arch/x86/include/asm/fpu/internal.h
    +++ b/arch/x86/include/asm/fpu/internal.h
    @@ -308,7 +308,7 @@ static inline int restore_fpu_checking(struct fpu *fpu)
    "fnclex\n\t"
    "emms\n\t"
    "fildl %P[addr]" /* set F?P to defined value */
    - : : [addr] "m" (fpu->has_fpu));
    + : : [addr] "m" (fpu->fpregs_active));
    }

    return fpu_restore_checking(fpu);
    @@ -317,14 +317,14 @@ static inline int restore_fpu_checking(struct fpu *fpu)
    /* Must be paired with an 'stts' after! */
    static inline void __thread_clear_has_fpu(struct fpu *fpu)
    {
    - fpu->has_fpu = 0;
    + fpu->fpregs_active = 0;
    this_cpu_write(fpu_fpregs_owner_ctx, NULL);
    }

    /* Must be paired with a 'clts' before! */
    static inline void __thread_set_has_fpu(struct fpu *fpu)
    {
    - fpu->has_fpu = 1;
    + fpu->fpregs_active = 1;
    this_cpu_write(fpu_fpregs_owner_ctx, fpu);
    }

    @@ -357,7 +357,7 @@ static inline void drop_fpu(struct fpu *fpu)
    preempt_disable();
    fpu->counter = 0;

    - if (fpu->has_fpu) {
    + if (fpu->fpregs_active) {
    /* Ignore delayed exceptions from user space */
    asm volatile("1: fwait\n"
    "2:\n"
    @@ -416,14 +416,14 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu)
    fpu.preload = new_fpu->fpstate_active &&
    (use_eager_fpu() || new_fpu->counter > 5);

    - if (old_fpu->has_fpu) {
    + if (old_fpu->fpregs_active) {
    if (!fpu_save_init(old_fpu))
    old_fpu->last_cpu = -1;
    else
    old_fpu->last_cpu = cpu;

    /* But leave fpu_fpregs_owner_ctx! */
    - old_fpu->has_fpu = 0;
    + old_fpu->fpregs_active = 0;

    /* Don't change CR0.TS if we just switch! */
    if (fpu.preload) {
    diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
    index 8a5120a3b48b..231a8f53b2f8 100644
    --- a/arch/x86/include/asm/fpu/types.h
    +++ b/arch/x86/include/asm/fpu/types.h
    @@ -142,7 +142,7 @@ struct fpu {
    */
    unsigned int last_cpu;

    - unsigned int has_fpu;
    + unsigned int fpregs_active;
    union thread_xstate *state;
    /*
    * This counter contains the number of consecutive context switches
    diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
    index 35ef1f9b56b3..a7fb56266a2d 100644
    --- a/arch/x86/kernel/fpu/core.c
    +++ b/arch/x86/kernel/fpu/core.c
    @@ -62,7 +62,7 @@ static bool interrupted_kernel_fpu_idle(void)
    if (use_eager_fpu())
    return true;

    - return !current->thread.fpu.has_fpu && (read_cr0() & X86_CR0_TS);
    + return !current->thread.fpu.fpregs_active && (read_cr0() & X86_CR0_TS);
    }

    /*
    @@ -100,7 +100,7 @@ void __kernel_fpu_begin(void)

    kernel_fpu_disable();

    - if (fpu->has_fpu) {
    + if (fpu->fpregs_active) {
    fpu_save_init(fpu);
    } else {
    this_cpu_write(fpu_fpregs_owner_ctx, NULL);
    @@ -114,7 +114,7 @@ void __kernel_fpu_end(void)
    {
    struct fpu *fpu = &current->thread.fpu;

    - if (fpu->has_fpu) {
    + if (fpu->fpregs_active) {
    if (WARN_ON(restore_fpu_checking(fpu)))
    fpu_reset_state(fpu);
    } else if (!use_eager_fpu()) {
    @@ -147,7 +147,7 @@ void fpu__save(struct fpu *fpu)
    WARN_ON(fpu != &current->thread.fpu);

    preempt_disable();
    - if (fpu->has_fpu) {
    + if (fpu->fpregs_active) {
    if (use_eager_fpu()) {
    __save_fpu(fpu);
    } else {
    @@ -243,7 +243,7 @@ static void fpu_copy(struct fpu *dst_fpu, struct fpu *src_fpu)
    int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
    {
    dst_fpu->counter = 0;
    - dst_fpu->has_fpu = 0;
    + dst_fpu->fpregs_active = 0;
    dst_fpu->state = NULL;
    dst_fpu->last_cpu = -1;

    --
    2.1.0


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