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 */ 66