kern_context.c revision 218327 
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 218327 2011-02-05 15:10:27Z kib $");
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/syscallsubr.h>
36#include <sys/sysent.h>
37#include <sys/systm.h>
38#include <sys/sysproto.h>
39#include <sys/signalvar.h>
40#include <sys/ucontext.h>
41
42/*
43 * The first two fields of a ucontext_t are the signal mask and the machine
44 * context.  The next field is uc_link; we want to avoid destroying the link
45 * when copying out contexts.
46 */
47#define	UC_COPY_SIZE	offsetof(ucontext_t, uc_link)
48
49#ifndef _SYS_SYSPROTO_H_
50struct getcontext_args {
51	struct __ucontext *ucp;
52}
53struct setcontext_args {
54	const struct __ucontext_t *ucp;
55}
56struct swapcontext_args {
57	struct __ucontext *oucp;
58	const struct __ucontext_t *ucp;
59}
60#endif
61
62int
63getcontext(struct thread *td, struct getcontext_args *uap)
64{
65	ucontext_t uc;
66	int ret;
67
68	if (uap->ucp == NULL)
69		ret = EINVAL;
70	else {
71		get_mcontext(td, &uc.uc_mcontext, GET_MC_CLEAR_RET);
72		PROC_LOCK(td->td_proc);
73		uc.uc_sigmask = td->td_sigmask;
74		PROC_UNLOCK(td->td_proc);
75		bzero(uc.__spare__, sizeof(uc.__spare__));
76		ret = copyout(&uc, uap->ucp, UC_COPY_SIZE);
77	}
78	return (ret);
79}
80
81int
82setcontext(struct thread *td, struct setcontext_args *uap)
83{
84	ucontext_t uc;
85	int ret;
86
87	if (uap->ucp == NULL)
88		ret = EINVAL;
89	else {
90		ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
91		if (ret == 0) {
92			ret = set_mcontext(td, &uc.uc_mcontext);
93			if (ret == 0) {
94				kern_sigprocmask(td, SIG_SETMASK, &uc.uc_sigmask,
95				    NULL, 0);
96			}
97		}
98	}
99	return (ret == 0 ? EJUSTRETURN : ret);
100}
101
102int
103swapcontext(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		bzero(uc.__spare__, sizeof(uc.__spare__));
113		PROC_LOCK(td->td_proc);
114		uc.uc_sigmask = td->td_sigmask;
115		PROC_UNLOCK(td->td_proc);
116		ret = copyout(&uc, uap->oucp, UC_COPY_SIZE);
117		if (ret == 0) {
118			ret = copyin(uap->ucp, &uc, UC_COPY_SIZE);
119			if (ret == 0) {
120				ret = set_mcontext(td, &uc.uc_mcontext);
121				if (ret == 0) {
122					kern_sigprocmask(td, SIG_SETMASK,
123					    &uc.uc_sigmask, NULL, 0);
124				}
125			}
126		}
127	}
128	return (ret == 0 ? EJUSTRETURN : ret);
129}
130