xref: /illumos-gate/usr/src/uts/common/sys/kfpu.h (revision 1a2d662a91cee3bf82f41cd47c7ae6f3825d9db2)
1 /*
2  * This file and its contents are supplied under the terms of the
3  * Common Development and Distribution License ("CDDL"), version 1.0.
4  * You may only use this file in accordance with the terms of version
5  * 1.0 of the CDDL.
6  *
7  * A full copy of the text of the CDDL should have accompanied this
8  * source.  A copy of the CDDL is also available via the Internet at
9  * http://www.illumos.org/license/CDDL.
10  */
11 
12 /*
13  * Copyright 2020 Joyent, Inc.
14  */
15 
16 #ifndef _SYS_KFPU_H
17 #define	_SYS_KFPU_H
18 
19 /*
20  * This header file provides a means for the kernel to opt into using the FPU.
21  * Care should be exercised when using the FPU.
22  */
23 
24 #include <sys/types.h>
25 
26 #ifdef __cplusplus
27 extern "C" {
28 #endif
29 
30 typedef struct kfpu_state kfpu_state_t;
31 
32 /*
33  * Allocate a new kernel FPU state. This may be allocated at a time independent
34  * from its use. It will stay around until such a time as kernel_fpu_free() is
35  * called. A given kernel FPU state may only be used by a single thread at any
36  * time; however, it is not bound to a given thread.
37  */
38 extern kfpu_state_t *kernel_fpu_alloc(int);
39 extern void kernel_fpu_free(kfpu_state_t *);
40 
41 /*
42  * These functions begin and end the use of the kernel FPU. Once this is called,
43  * a given kernel thread will be allowed to use the FPU. This will be saved and
44  * restored across context switches.
45  */
46 extern void kernel_fpu_begin(kfpu_state_t *, uint_t);
47 extern void kernel_fpu_end(kfpu_state_t *, uint_t);
48 
49 /*
50  * Internal validation function.
51  */
52 extern void kernel_fpu_no_swtch(void);
53 
54 /*
55  * Flag definitions for kernel_fpu_begin and kernel_fpu_end.
56  */
57 #define	KFPU_NO_STATE	0x01	/* kfpu_state_t not passed; use preemption */
58 #define	KFPU_USE_LWP	0x02	/* kfpu_state_t not passed; use lwp */
59 
60 #ifdef __cplusplus
61 }
62 #endif
63 
64 #endif /* _SYS_KFPU_H */
65