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/* SPDX-License-Identifier: GPL-2.0 */
* Copyright (C) 1994 Linus Torvalds
* Pentium III FXSR, SSE support
* General FPU state handling cleanups
* Gareth Hughes <>, 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 irq/softirq you need to check first with
* irq_fpu_usable() if it is possible.
/* Kernel FPU states to initialize in kernel_fpu_begin_mask() */
#define KFPU_387 _BITUL(0) /* 387 state will be initialized */
#define KFPU_MXCSR _BITUL(1) /* MXCSR will be initialized */
extern void kernel_fpu_begin_mask(unsigned int kfpu_mask);
extern void kernel_fpu_end(void);
extern bool irq_fpu_usable(void);
extern void fpregs_mark_activate(void);
/* Code that is unaware of kernel_fpu_begin_mask() can use this */
static inline void kernel_fpu_begin(void)
kernel_fpu_begin_mask(KFPU_387 | KFPU_MXCSR);
* 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)
static inline void fpregs_unlock(void)
extern void fpregs_assert_state_consistent(void);
static inline void fpregs_assert_state_consistent(void) { }
* 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 */