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
49void
50lkpi_kernel_fpu_begin(void)
51{
52	if ((current->fpu_ctx_level)++ == 0)
53		fpu_kern_enter(curthread, NULL, FPU_KERN_NOCTX);
54}
55
56void
57lkpi_kernel_fpu_end(void)
58{
59	if (--(current->fpu_ctx_level) == 0)
60		fpu_kern_leave(curthread, NULL);
61}
62
63void
64lkpi_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
83void
84lkpi_kernel_fpu_begin(void)
85{
86}
87
88void
89lkpi_kernel_fpu_end(void)
90{
91}
92
93void
94lkpi_fpu_safe_exec(fpu_safe_exec_cb_t func, void *ctx)
95{
96	func(ctx);
97}
98
99#endif
100