1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2002 Daniel M. Eischen <deischen@freebsd.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/param.h>
30#include <sys/kernel.h>
31#include <sys/lock.h>
32#include <sys/mutex.h>
33#include <sys/proc.h>
34#include <sys/syscallsubr.h>
35#include <sys/systm.h>
36#include <sys/sysproto.h>
37#include <sys/signalvar.h>
38#include <sys/ucontext.h>
39
40/*
41 * The first two fields of a ucontext_t are the signal mask and the machine
42 * context.  The next field is uc_link; we want to avoid destroying the link
43 * when copying out contexts.
44 */
45#define	UC_COPY_SIZE	offsetof(ucontext_t, uc_link)
46
47#ifndef _SYS_SYSPROTO_H_
48struct getcontext_args {
49	struct __ucontext *ucp;
50}
51struct setcontext_args {
52	const struct __ucontext_t *ucp;
53}
54struct swapcontext_args {
55	struct __ucontext *oucp;
56	const struct __ucontext_t *ucp;
57}
58#endif
59
60int
61sys_getcontext(struct thread *td, struct getcontext_args *uap)
62{
63	ucontext_t uc;
64	int ret;
65
66	if (uap->ucp == NULL)
67		ret = EINVAL;
68	else {
69		bzero(&uc, sizeof(ucontext_t));
70		get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
71		PROC_LOCK(td->td_proc);
72		uc.uc_sigmask = td->td_sigmask;
73		PROC_UNLOCK(td->td_proc);
74		ret = copyout(&uc, uap->ucp, UC_COPY_SIZE);
75	}
76	return (ret);
77}
78
79int
80sys_setcontext(struct thread *td, struct setcontext_args *uap)
81{
82	ucontext_t uc;
83	int ret;
84
85	if (uap->ucp == NULL)
86		ret = EINVAL;
87	else {
88		ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
89		if (ret == 0) {
90			ret = set_mcontext(td, &uc.uc_mcontext);
91			if (ret == 0) {
92				kern_sigprocmask(td, SIG_SETMASK, &uc.uc_sigmask,
93				    NULL, 0);
94			}
95		}
96	}
97	return (ret == 0 ? EJUSTRETURN : ret);
98}
99
100int
101sys_swapcontext(struct thread *td, struct swapcontext_args *uap)
102{
103	ucontext_t uc;
104	int ret;
105
106	if (uap->oucp == NULL || uap->ucp == NULL)
107		ret = EINVAL;
108	else {
109		bzero(&uc, sizeof(ucontext_t));
110		get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
111		PROC_LOCK(td->td_proc);
112		uc.uc_sigmask = td->td_sigmask;
113		PROC_UNLOCK(td->td_proc);
114		ret = copyout(&uc, uap->oucp, UC_COPY_SIZE);
115		if (ret == 0) {
116			ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
117			if (ret == 0) {
118				ret = set_mcontext(td, &uc.uc_mcontext);
119				if (ret == 0) {
120					kern_sigprocmask(td, SIG_SETMASK,
121					    &uc.uc_sigmask, NULL, 0);
122				}
123			}
124		}
125	}
126	return (ret == 0 ? EJUSTRETURN : ret);
127}
128