xref: /freebsd/share/examples/kld/syscall/module/syscall.c (revision d056fa046c6a91b90cd98165face0e42a33a5173)
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  * $FreeBSD$
27  */
28 
29 #include <sys/types.h>
30 #include <sys/param.h>
31 #include <sys/proc.h>
32 #include <sys/module.h>
33 #include <sys/sysent.h>
34 #include <sys/kernel.h>
35 #include <sys/systm.h>
36 
37 /*
38  * The function for implementing the syscall.
39  */
40 
41 static int
42 hello (struct thread *td, void *arg)
43 {
44 	printf ("hello kernel\n");
45 	return 0;
46 }
47 
48 /*
49  * The `sysent' for the new syscall
50  */
51 
52 static struct sysent hello_sysent = {
53 	0,			/* sy_narg */
54 	hello			/* sy_call */
55 };
56 
57 /*
58  * The offset in sysent where the syscall is allocated.
59  */
60 
61 static int offset = NO_SYSCALL;
62 
63 /*
64  * The function called at load/unload.
65  */
66 
67 static int
68 load (struct module *module, int cmd, void *arg)
69 {
70 	int error = 0;
71 
72 	switch (cmd) {
73 	case MOD_LOAD :
74 		printf ("syscall loaded at %d\n", offset);
75 		break;
76 	case MOD_UNLOAD :
77 		printf ("syscall unloaded from %d\n", offset);
78 		break;
79 	default :
80 		error = EOPNOTSUPP;
81 		break;
82 	}
83 	return error;
84 }
85 
86 SYSCALL_MODULE(syscall, &offset, &hello_sysent, load, NULL);
87