LXR linux/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 */
  22extern void kernel_fpu_begin(void);
  23extern void kernel_fpu_end(void);
  24extern bool irq_fpu_usable(void);
  25extern 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 */
  33static inline void fpregs_lock(void)
  34{
  35        preempt_disable();
  36        local_bh_disable();
  37}
  38
  39static inline void fpregs_unlock(void)
  40{
  41        local_bh_enable();
  42        preempt_enable();
  43}
  44
  45#ifdef CONFIG_X86_DEBUG_FPU
  46extern void fpregs_assert_state_consistent(void);
  47#else
  48static inline void fpregs_assert_state_consistent(void) { }
  49#endif
  50
  51/*
  52 * Load the task FPU state before returning to userspace.
  53 */
  54extern 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 */
  63extern int cpu_has_xfeatures(u64 xfeatures_mask, const char **feature_name);
  64
  65#endif /* _ASM_X86_FPU_API_H */
  66