1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2020 Val Packett <val@packett.cool>
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
16  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
19  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25  * SUCH DAMAGE.
26  */
27 
28 #include <sys/types.h>
29 #include <sys/param.h>
30 #include <sys/proc.h>
31 #include <sys/kernel.h>
32 
33 #include <linux/compat.h>
34 #include <linux/sched.h>
35 
36 #include <asm/fpu/api.h>
37 
38 #if defined(__aarch64__) || defined(__arm__) || defined(__amd64__) ||	\
39     defined(__i386__) || defined(__powerpc64__)
40 
41 #include <machine/fpu.h>
42 
43 /*
44  * Technically the Linux API isn't supposed to allow nesting sections
45  * either, but currently used versions of GPU drivers rely on nesting
46  * working, so we only enter the section on the outermost level.
47  */
48 
49 void
50 lkpi_kernel_fpu_begin(void)
51 {
52 	if ((current->fpu_ctx_level)++ == 0)
53 		fpu_kern_enter(curthread, NULL, FPU_KERN_NOCTX);
54 }
55 
56 void
57 lkpi_kernel_fpu_end(void)
58 {
59 	if (--(current->fpu_ctx_level) == 0)
60 		fpu_kern_leave(curthread, NULL);
61 }
62 
63 void
64 lkpi_fpu_safe_exec(fpu_safe_exec_cb_t func, void *ctx)
65 {
66 	unsigned int save_fpu_level;
67 
68 	save_fpu_level =
69 	    __current_unallocated(curthread) ? 0 : current->fpu_ctx_level;
70 	if (__predict_false(save_fpu_level != 0)) {
71 		current->fpu_ctx_level = 1;
72 		kernel_fpu_end();
73 	}
74 	func(ctx);
75 	if (__predict_false(save_fpu_level != 0)) {
76 		kernel_fpu_begin();
77 		current->fpu_ctx_level = save_fpu_level;
78 	}
79 }
80 
81 #else
82 
83 void
84 lkpi_kernel_fpu_begin(void)
85 {
86 }
87 
88 void
89 lkpi_kernel_fpu_end(void)
90 {
91 }
92 
93 void
94 lkpi_fpu_safe_exec(fpu_safe_exec_cb_t func, void *ctx)
95 {
96 	func(ctx);
97 }
98 
99 #endif
100