arch/x86/include/asm/fpu/api.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /*
   3  * Copyright (C) 1994 Linus Torvalds
   4  *
   5  * Pentium III FXSR, SSE support
   6  * General FPU state handling cleanups
   7  *      Gareth Hughes <gareth@valinux.com>, May 2000
   8  * x86-64 work by Andi Kleen 2002
   9  */
  10
  11 #ifndef _ASM_X86_FPU_API_H
  12 #define _ASM_X86_FPU_API_H
  13 #include <linux/bottom_half.h>
  14
  15 /*
  16  * Use kernel_fpu_begin/end() if you intend to use FPU in kernel context. It
  17  * disables preemption so be careful if you intend to use it for long periods
  18  * of time.
  19  * If you intend to use the FPU in softirq you need to check first with
  20  * irq_fpu_usable() if it is possible.
  21  */
  22 extern void kernel_fpu_begin(void);
  23 extern void kernel_fpu_end(void);
  24 extern bool irq_fpu_usable(void);
  25 extern void fpregs_mark_activate(void);
  26
  27 /*
  28  * Use fpregs_lock() while editing CPU's FPU registers or fpu->state.
  29  * A context switch will (and softirq might) save CPU's FPU registers to
  30  * fpu->state and set TIF_NEED_FPU_LOAD leaving CPU's FPU registers in
  31  * a random state.
  32  */
  33 static inline void fpregs_lock(void)
  34 {
  35         preempt_disable();
  36         local_bh_disable();
  37 }
  38
  39 static inline void fpregs_unlock(void)
  40 {
  41         local_bh_enable();
  42         preempt_enable();
  43 }
  44
  45 #ifdef CONFIG_X86_DEBUG_FPU
  46 extern void fpregs_assert_state_consistent(void);
  47 #else
  48 static inline void fpregs_assert_state_consistent(void) { }
  49 #endif
  50
  51 /*
  52  * Load the task FPU state before returning to userspace.
  53  */
  54 extern void switch_fpu_return(void);
  55
  56 /*
  57  * Query the presence of one or more xfeatures. Works on any legacy CPU as well.
  58  *
  59  * If 'feature_name' is set then put a human-readable description of
  60  * the feature there as well - this can be used to print error (or success)
  61  * messages.
  62  */
  63 extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name);
  64
  65 #endif /* _ASM_X86_FPU_API_H */