text: /* SPDX-License-Identifier: GPL-2.0 */
  /*
   * Copyright (C) 1994 Linus Torvalds
   *
   * Pentium III FXSR, SSE support
   * General FPU state handling cleanups
   *	Gareth Hughes <gareth@valinux.com>, May 2000
   * x86-64 work by Andi Kleen 2002
   */
  
  #ifndef _ASM_X86_FPU_API_H
  #define _ASM_X86_FPU_API_H
  #include <linux/bottom_half.h>
  
  /*
   * Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It
   * disables preemption so be careful if you intend to use it for long periods
   * of time.
   * If you intend to use the FPU in softirq you need to check first with
   * irq_fpu_usable() if it is possible.
   */
  extern void kernel_fpu_begin(void);
  extern void kernel_fpu_end(void);
  extern bool irq_fpu_usable(void);
  extern void fpregs_mark_activate(void);
  
  /*
   * Use fpregs_lock() while editing CPU's FPU registers or fpu->state.
   * A context switch will (and softirq might) save CPU's FPU registers to
   * fpu->state and set TIF_NEED_FPU_LOAD leaving CPU's FPU registers in
   * a random state.
   */
  static inline void fpregs_lock(void)
  {
  	preempt_disable();
  	local_bh_disable();
  }
  
  static inline void fpregs_unlock(void)
  {
  	local_bh_enable();
  	preempt_enable();
  }
  
  #ifdef CONFIG_X86_DEBUG_FPU
  extern void fpregs_assert_state_consistent(void);
  #else
  static inline void fpregs_assert_state_consistent(void) { }
  #endif
  
  /*
   * Load the task FPU state before returning to userspace.
   */
  extern void switch_fpu_return(void);
  
  /*
   * Query the presence of one or more xfeatures. Works on any legacy CPU as well.
   *
   * If 'feature_name' is set then put a human-readable description of
   * the feature there as well - this can be used to print error (or success)
   * messages.
   */
  extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name);
  
  #endif /* _ASM_X86_FPU_API_H */
  