1 files changed, 11 insertions, 27 deletions

diff --git a/arch/x86/include/asm/fpu/sched.h b/arch/x86/include/asm/fpu/sched.h
index c485f1944c5f..c060549c6c94 100644
--- a/arch/x86/include/asm/fpu/sched.h
+++ b/arch/x86/include/asm/fpu/sched.h
@@ -10,7 +10,7 @@
 #include <asm/trace/fpu.h>
 
 extern void save_fpregs_to_fpstate(struct fpu *fpu);
-extern void fpu__drop(struct fpu *fpu);
+extern void fpu__drop(struct task_struct *tsk);
 extern int  fpu_clone(struct task_struct *dst, unsigned long clone_flags, bool minimal,
 		      unsigned long shstk_addr);
 extern void fpu_flush_thread(void);
@@ -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 = &old->thread.fpu;
+		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 */