diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h index 0dbc08282291..61609b963eab 100644 --- a/arch/x86/include/asm/fpu-internal.h +++ b/arch/x86/include/asm/fpu-internal.h @@ -67,6 +67,34 @@ extern void finit_soft_fpu(struct i387_soft_struct *soft); static inline void finit_soft_fpu(struct i387_soft_struct *soft) {} #endif +/* + * Must be run with preemption disabled: this clears the fpu_owner_task, + * on this CPU. + * + * This will disable any lazy FPU state restore of the current FPU state, + * but if the current thread owns the FPU, it will still be saved by. + */ +static inline void __cpu_disable_lazy_restore(unsigned int cpu) +{ + per_cpu(fpu_owner_task, cpu) = NULL; +} + +/* + * Used to indicate that the FPU state in memory is newer than the FPU + * state in registers, and the FPU state should be reloaded next time the + * task is run. Only safe on the current task, or non-running tasks. + */ +static inline void task_disable_lazy_fpu_restore(struct task_struct *tsk) +{ + tsk->thread.fpu.last_cpu = ~0; +} + +static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu) +{ + return new == this_cpu_read_stable(fpu_owner_task) && + cpu == new->thread.fpu.last_cpu; +} + static inline int is_ia32_compat_frame(void) { return config_enabled(CONFIG_IA32_EMULATION) && @@ -400,24 +428,6 @@ static inline void drop_init_fpu(struct task_struct *tsk) */ typedef struct { int preload; } fpu_switch_t; -/* - * Must be run with preemption disabled: this clears the fpu_owner_task, - * on this CPU. - * - * This will disable any lazy FPU state restore of the current FPU state, - * but if the current thread owns the FPU, it will still be saved by. - */ -static inline void __cpu_disable_lazy_restore(unsigned int cpu) -{ - per_cpu(fpu_owner_task, cpu) = NULL; -} - -static inline int fpu_lazy_restore(struct task_struct *new, unsigned int cpu) -{ - return new == this_cpu_read_stable(fpu_owner_task) && - cpu == new->thread.fpu.last_cpu; -} - static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct task_struct *new, int cpu) { fpu_switch_t fpu; @@ -426,13 +436,17 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta * If the task has used the math, pre-load the FPU on xsave processors * or if the past 5 consecutive context-switches used math. */ - fpu.preload = tsk_used_math(new) && (use_eager_fpu() || - new->thread.fpu_counter > 5); + fpu.preload = tsk_used_math(new) && + (use_eager_fpu() || new->thread.fpu_counter > 5); + if (__thread_has_fpu(old)) { if (!__save_init_fpu(old)) - cpu = ~0; - old->thread.fpu.last_cpu = cpu; - old->thread.fpu.has_fpu = 0; /* But leave fpu_owner_task! */ + task_disable_lazy_fpu_restore(old); + else + old->thread.fpu.last_cpu = cpu; + + /* But leave fpu_owner_task! */ + old->thread.fpu.has_fpu = 0; /* Don't change CR0.TS if we just switch! */ if (fpu.preload) { @@ -443,10 +457,10 @@ static inline fpu_switch_t switch_fpu_prepare(struct task_struct *old, struct ta stts(); } else { old->thread.fpu_counter = 0; - old->thread.fpu.last_cpu = ~0; + task_disable_lazy_fpu_restore(old); if (fpu.preload) { new->thread.fpu_counter++; - if (!use_eager_fpu() && fpu_lazy_restore(new, cpu)) + if (fpu_lazy_restore(new, cpu)) fpu.preload = 0; else prefetch(new->thread.fpu.state); @@ -519,24 +533,6 @@ static inline void __save_fpu(struct task_struct *tsk) fpu_fxsave(&tsk->thread.fpu); } -/* - * These disable preemption on their own and are safe - */ -static inline void save_init_fpu(struct task_struct *tsk) -{ - WARN_ON_ONCE(!__thread_has_fpu(tsk)); - - if (use_eager_fpu()) { - __save_fpu(tsk); - return; - } - - preempt_disable(); - __save_init_fpu(tsk); - __thread_fpu_end(tsk); - preempt_enable(); -} - /* * i387 state interaction */ diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index 81049ffab2d6..f59d80622e60 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -119,10 +119,13 @@ void unlazy_fpu(struct task_struct *tsk) { preempt_disable(); if (__thread_has_fpu(tsk)) { - __save_init_fpu(tsk); - __thread_fpu_end(tsk); - } else - tsk->thread.fpu_counter = 0; + if (use_eager_fpu()) { + __save_fpu(tsk); + } else { + __save_init_fpu(tsk); + __thread_fpu_end(tsk); + } + } preempt_enable(); } EXPORT_SYMBOL(unlazy_fpu); @@ -246,7 +249,7 @@ int init_fpu(struct task_struct *tsk) if (tsk_used_math(tsk)) { if (cpu_has_fpu && tsk == current) unlazy_fpu(tsk); - tsk->thread.fpu.last_cpu = ~0; + task_disable_lazy_fpu_restore(tsk); return 0; } diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index e127ddaa2d5a..ce8b10351e28 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -68,8 +68,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) dst->thread.fpu_counter = 0; dst->thread.fpu.has_fpu = 0; - dst->thread.fpu.last_cpu = ~0; dst->thread.fpu.state = NULL; + task_disable_lazy_fpu_restore(dst); if (tsk_used_math(src)) { int err = fpu_alloc(&dst->thread.fpu); if (err) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 9d2073e2ecc9..92b83e299ed3 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -734,7 +734,7 @@ static void math_error(struct pt_regs *regs, int error_code, int trapnr) /* * Save the info for the exception handler and clear the error. */ - save_init_fpu(task); + unlazy_fpu(task); task->thread.trap_nr = trapnr; task->thread.error_code = error_code; info.si_signo = SIGFPE;