diff options
| -rw-r--r-- | arch/x86/include/asm/fpu/sched.h | 34 | ||||
| -rw-r--r-- | arch/x86/kernel/process_32.c | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/process_64.c | 5 |
3 files changed, 11 insertions, 33 deletions
diff --git a/arch/x86/include/asm/fpu/sched.h b/arch/x86/include/asm/fpu/sched.h index 5fd12634bcc4..c060549c6c94 100644 --- a/arch/x86/include/asm/fpu/sched.h +++ b/arch/x86/include/asm/fpu/sched.h @@ -18,31 +18,25 @@ extern void fpu_flush_thread(void); /* * FPU state switching for scheduling. * - * This is a two-stage process: + * switch_fpu() saves the old state and sets TIF_NEED_FPU_LOAD if + * TIF_NEED_FPU_LOAD is not set. This is done within the context + * of the old process. * - * - switch_fpu_prepare() saves the old state. - * This is done within the context of the old process. - * - * - switch_fpu_finish() sets TIF_NEED_FPU_LOAD; the floating point state - * will get loaded on return to userspace, or when the kernel needs it. - * - * If TIF_NEED_FPU_LOAD is cleared then the CPU's FPU registers - * are saved in the current thread'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 + * Once TIF_NEED_FPU_LOAD is set, it is required to load the * registers before returning to userland or using the content * otherwise. * * The FPU context is only stored/restored for a user task and * PF_KTHREAD is used to distinguish between kernel and user threads. */ -static inline void switch_fpu_prepare(struct task_struct *old, int cpu) +static inline void switch_fpu(struct task_struct *old, int cpu) { - if (cpu_feature_enabled(X86_FEATURE_FPU) && + if (!test_tsk_thread_flag(old, TIF_NEED_FPU_LOAD) && + cpu_feature_enabled(X86_FEATURE_FPU) && !(old->flags & (PF_KTHREAD | PF_USER_WORKER))) { struct fpu *old_fpu = x86_task_fpu(old); + set_tsk_thread_flag(old, TIF_NEED_FPU_LOAD); save_fpregs_to_fpstate(old_fpu); /* * The save operation preserved register state, so the @@ -50,7 +44,7 @@ static inline void switch_fpu_prepare(struct task_struct *old, int cpu) * current CPU number in @old_fpu, so the next return * to user space can avoid the FPU register restore * when is returns on the same CPU and still owns the - * context. + * context. See fpregs_restore_userregs(). */ old_fpu->last_cpu = cpu; @@ -58,14 +52,4 @@ static inline void switch_fpu_prepare(struct task_struct *old, int cpu) } } -/* - * Delay loading of the complete FPU state until the return to userland. - * PKRU is handled separately. - */ -static inline void switch_fpu_finish(struct task_struct *new) -{ - if (cpu_feature_enabled(X86_FEATURE_FPU)) - set_tsk_thread_flag(new, TIF_NEED_FPU_LOAD); -} - #endif /* _ASM_X86_FPU_SCHED_H */ diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 4636ef359973..9bd4fa694da5 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -160,8 +160,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) /* never put a printk in __switch_to... printk() calls wake_up*() indirectly */ - if (!test_tsk_thread_flag(prev_p, TIF_NEED_FPU_LOAD)) - switch_fpu_prepare(prev_p, cpu); + switch_fpu(prev_p, cpu); /* * Save away %gs. No need to save %fs, as it was saved on the @@ -208,8 +207,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) raw_cpu_write(current_task, next_p); - switch_fpu_finish(next_p); - /* Load the Intel cache allocation PQR MSR. */ resctrl_sched_in(next_p); diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 7196ca7048be..d55310d3133c 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -616,8 +616,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_ENTRY) && this_cpu_read(hardirq_stack_inuse)); - if (!test_tsk_thread_flag(prev_p, TIF_NEED_FPU_LOAD)) - switch_fpu_prepare(prev_p, cpu); + switch_fpu(prev_p, cpu); /* We must save %fs and %gs before load_TLS() because * %fs and %gs may be cleared by load_TLS(). @@ -671,8 +670,6 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) raw_cpu_write(current_task, next_p); raw_cpu_write(cpu_current_top_of_stack, task_top_of_stack(next_p)); - switch_fpu_finish(next_p); - /* Reload sp0. */ update_task_stack(next_p); |