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 */