kern_syscalls.c revision 48269 
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 *     $Id: kern_syscalls.c,v 1.3 1999/01/17 18:58:04 peter Exp $
27 */
28
29#include <sys/param.h>
30#include <sys/kernel.h>
31#include <sys/systm.h>
32#include <sys/malloc.h>
33#include <sys/sysproto.h>
34#include <sys/sysent.h>
35#include <sys/syscall.h>
36#include <sys/module.h>
37#include <sys/linker.h>
38#include <sys/proc.h>
39
40/*
41 * Acts like "nosys" but can be identified in sysent for dynamic call
42 * number assignment for a limited number of calls.
43 *
44 * Place holder for system call slots reserved for loadable modules.
45 */
46int
47lkmnosys(struct proc *p, struct nosys_args *args)
48{
49	return(nosys(p, args));
50}
51
52int
53syscall_register(int *offset, struct sysent *new_sysent,
54		 struct sysent *old_sysent)
55{
56       if (*offset == NO_SYSCALL) {
57               int i;
58
59               for (i = 1; i < SYS_MAXSYSCALL; ++i)
60                       if (sysent[i].sy_call == (sy_call_t *)lkmnosys)
61                               break;
62               if (i == SYS_MAXSYSCALL)
63                       return ENFILE;
64               *offset = i;
65       } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL)
66               return EINVAL;
67       else if (sysent[*offset].sy_call != (sy_call_t *)lkmnosys)
68               return EEXIST;
69
70       *old_sysent = sysent[*offset];
71       sysent[*offset] = *new_sysent;
72       return 0;
73}
74
75int
76syscall_deregister(int *offset, struct sysent *old_sysent)
77{
78       if (*offset)
79               sysent[*offset] = *old_sysent;
80       return 0;
81}
82
83int
84syscall_module_handler(struct module *mod, int what, void *arg)
85{
86       struct syscall_module_data *data = (struct syscall_module_data*)arg;
87       modspecific_t ms;
88       int error;
89
90       switch (what) {
91       case MOD_LOAD :
92               error = syscall_register(data->offset, data->new_sysent,
93                                        &data->old_sysent);
94               if (error)
95                       return error;
96	       ms.intval = *data->offset;
97	       module_setspecific(mod, &ms);
98               if (data->chainevh)
99                       error = data->chainevh(mod, what, data->chainarg);
100               return error;
101
102       case MOD_UNLOAD :
103               if (data->chainevh) {
104                       error = data->chainevh(mod, what, data->chainarg);
105                       if (error)
106                               return error;
107               }
108               error = syscall_deregister(data->offset, &data->old_sysent);
109               return error;
110       }
111
112       if (data->chainevh)
113               return data->chainevh(mod, what, data->chainarg);
114       else
115               return 0;
116}
117