1 /*-
2 * Copyright (c) 1999 Assar Westerlund
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 * $FreeBSD: releng/5.1/sys/kern/kern_syscalls.c 92547 2002-03-18 07:45:30Z arr $
27 */
28
29 #include <sys/param.h>
30 #include <sys/sysproto.h>
31 #include <sys/sysent.h>
32 #include <sys/syscall.h>
33 #include <sys/lock.h>
34 #include <sys/mutex.h>
35 #include <sys/sx.h>
36 #include <sys/module.h>
37
38 /*
39 * Acts like "nosys" but can be identified in sysent for dynamic call
40 * number assignment for a limited number of calls.
41 *
42 * Place holder for system call slots reserved for loadable modules.
43 */
44 int
45 lkmnosys(struct thread *td, struct nosys_args *args)
46 {
47 return(nosys(td, args));
48 }
49
50 int
51 lkmressys(struct thread *td, struct nosys_args *args)
52 {
53 return(nosys(td, args));
54 }
55
56 int
57 syscall_register(int *offset, struct sysent *new_sysent,
58 struct sysent *old_sysent)
59 {
60 if (*offset == NO_SYSCALL) {
61 int i;
62
63 for (i = 1; i < SYS_MAXSYSCALL; ++i)
64 if (sysent[i].sy_call == (sy_call_t *)lkmnosys)
65 break;
66 if (i == SYS_MAXSYSCALL)
67 return ENFILE;
68 *offset = i;
69 } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL)
70 return EINVAL;
71 else if (sysent[*offset].sy_call != (sy_call_t *)lkmnosys &&
72 sysent[*offset].sy_call != (sy_call_t *)lkmressys)
73 return EEXIST;
74
75 *old_sysent = sysent[*offset];
76 sysent[*offset] = *new_sysent;
77 return 0;
78 }
79
80 int
81 syscall_deregister(int *offset, struct sysent *old_sysent)
82 {
83 if (*offset)
84 sysent[*offset] = *old_sysent;
85 return 0;
86 }
87
88 int
89 syscall_module_handler(struct module *mod, int what, void *arg)
90 {
91 struct syscall_module_data *data = (struct syscall_module_data*)arg;
92 modspecific_t ms;
93 int error;
94
95 switch (what) {
96 case MOD_LOAD :
97 error = syscall_register(data->offset, data->new_sysent,
98 &data->old_sysent);
99 if (error)
100 return error;
101 ms.intval = *data->offset;
102 MOD_XLOCK;
103 module_setspecific(mod, &ms);
104 MOD_XUNLOCK;
105 if (data->chainevh)
106 error = data->chainevh(mod, what, data->chainarg);
107 return error;
108
109 case MOD_UNLOAD :
110 if (data->chainevh) {
111 error = data->chainevh(mod, what, data->chainarg);
112 if (error)
113 return error;
114 }
115 error = syscall_deregister(data->offset, &data->old_sysent);
116 return error;
117 }
118
119 if (data->chainevh)
120 return data->chainevh(mod, what, data->chainarg);
121 else
122 return 0;
123 }
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