xref: /freebsd/sys/kern/kern_context.c (revision 1e413cf93298b5b97441a21d9a50fdcd0ee9945e)
1 /*-
2  * Copyright (c) 2002 Daniel M. Eischen <deischen@freebsd.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <sys/param.h>
31 #include <sys/kernel.h>
32 #include <sys/lock.h>
33 #include <sys/mutex.h>
34 #include <sys/proc.h>
35 #include <sys/sysent.h>
36 #include <sys/systm.h>
37 #include <sys/sysproto.h>
38 #include <sys/signalvar.h>
39 #include <sys/ucontext.h>
40 
41 /*
42  * The first two fields of a ucontext_t are the signal mask and the machine
43  * context.  The next field is uc_link; we want to avoid destroying the link
44  * when copying out contexts.
45  */
46 #define	UC_COPY_SIZE	offsetof(ucontext_t, uc_link)
47 
48 #ifndef _SYS_SYSPROTO_H_
49 struct getcontext_args {
50 	struct __ucontext *ucp;
51 }
52 struct setcontext_args {
53 	const struct __ucontext_t *ucp;
54 }
55 struct swapcontext_args {
56 	struct __ucontext *oucp;
57 	const struct __ucontext_t *ucp;
58 }
59 #endif
60 
61 int
62 getcontext(struct thread *td, struct getcontext_args *uap)
63 {
64 	ucontext_t uc;
65 	int ret;
66 
67 	if (uap->ucp == NULL)
68 		ret = EINVAL;
69 	else {
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 
79 int
80 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 				SIG_CANTMASK(uc.uc_sigmask);
93 				PROC_LOCK(td->td_proc);
94 				td->td_sigmask = uc.uc_sigmask;
95 				PROC_UNLOCK(td->td_proc);
96 			}
97 		}
98 	}
99 	return (ret == 0 ? EJUSTRETURN : ret);
100 }
101 
102 int
103 swapcontext(struct thread *td, struct swapcontext_args *uap)
104 {
105 	ucontext_t uc;
106 	int ret;
107 
108 	if (uap->oucp == NULL || uap->ucp == NULL)
109 		ret = EINVAL;
110 	else {
111 		get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
112 		PROC_LOCK(td->td_proc);
113 		uc.uc_sigmask = td->td_sigmask;
114 		PROC_UNLOCK(td->td_proc);
115 		ret = copyout(&uc, uap->oucp, UC_COPY_SIZE);
116 		if (ret == 0) {
117 			ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
118 			if (ret == 0) {
119 				ret = set_mcontext(td, &uc.uc_mcontext);
120 				if (ret == 0) {
121 					SIG_CANTMASK(uc.uc_sigmask);
122 					PROC_LOCK(td->td_proc);
123 					td->td_sigmask = uc.uc_sigmask;
124 					PROC_UNLOCK(td->td_proc);
125 				}
126 			}
127 		}
128 	}
129 	return (ret == 0 ? EJUSTRETURN : ret);
130 }
131