kern_context.c revision 122364 
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: head/sys/kern/kern_context.c 122364 2003-11-09 20:31:04Z marcel $");
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
43 * the machine context.  The next field is uc_link; we want to
44 * avoid destroying the link when copying out contexts.
45 */
46#define	UC_COPY_SIZE	offsetof(ucontext_t, uc_link)
47
48#ifndef _SYS_SYSPROTO_H_
49struct getcontext_args {
50	struct __ucontext *ucp;
51}
52struct setcontext_args {
53	const struct __ucontext_t *ucp;
54}
55struct swapcontext_args {
56	struct __ucontext *oucp;
57	const struct __ucontext_t *ucp;
58}
59#endif
60
61/*
62 * MPSAFE
63 */
64int
65getcontext(struct thread *td, struct getcontext_args *uap)
66{
67	ucontext_t uc;
68	int ret;
69
70	if (uap->ucp == NULL)
71		ret = EINVAL;
72	else {
73		get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
74		PROC_LOCK(td->td_proc);
75		uc.uc_sigmask = td->td_sigmask;
76		PROC_UNLOCK(td->td_proc);
77		ret = copyout(&uc, uap->ucp, UC_COPY_SIZE);
78	}
79	return (ret);
80}
81
82/*
83 * MPSAFE
84 */
85int
86setcontext(struct thread *td, struct setcontext_args *uap)
87{
88	ucontext_t uc;
89	int ret;
90
91	if (uap->ucp == NULL)
92		ret = EINVAL;
93	else {
94		ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
95		if (ret == 0) {
96			ret = set_mcontext(td, &uc.uc_mcontext);
97			if (ret == 0) {
98				SIG_CANTMASK(uc.uc_sigmask);
99				PROC_LOCK(td->td_proc);
100				td->td_sigmask = uc.uc_sigmask;
101				PROC_UNLOCK(td->td_proc);
102			}
103		}
104	}
105	return (ret == 0 ? EJUSTRETURN : ret);
106}
107
108int
109swapcontext(struct thread *td, struct swapcontext_args *uap)
110{
111	ucontext_t uc;
112	int ret;
113
114	if (uap->oucp == NULL || uap->ucp == NULL)
115		ret = EINVAL;
116	else {
117		get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
118		PROC_LOCK(td->td_proc);
119		uc.uc_sigmask = td->td_sigmask;
120		PROC_UNLOCK(td->td_proc);
121		ret = copyout(&uc, uap->oucp, UC_COPY_SIZE);
122		if (ret == 0) {
123			ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
124			if (ret == 0) {
125				ret = set_mcontext(td, &uc.uc_mcontext);
126				if (ret == 0) {
127					SIG_CANTMASK(uc.uc_sigmask);
128					PROC_LOCK(td->td_proc);
129					td->td_sigmask = uc.uc_sigmask;
130					PROC_UNLOCK(td->td_proc);
131				}
132			}
133		}
134	}
135	return (ret == 0 ? EJUSTRETURN : ret);
136}
137