xref: /freebsd/share/examples/kld/syscall/module/syscall.c (revision e0c4386e7e71d93b0edc0c8fa156263fc4a8b0b6)
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 1999 Assar Westerlund
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #include <sys/param.h>
30 #include <sys/proc.h>
31 #include <sys/module.h>
32 #include <sys/sysproto.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 static int
41 hello(struct thread *td, void *arg)
42 {
43 
44 	printf("hello kernel\n");
45 	return (0);
46 }
47 
48 /*
49  * The `sysent' for the new syscall
50  */
51 static struct sysent hello_sysent = {
52 	.sy_narg = 0,
53 	.sy_call = hello
54 };
55 
56 /*
57  * The offset in sysent where the syscall is allocated.
58  */
59 static int offset = NO_SYSCALL;
60 
61 /*
62  * The function called at load/unload.
63  */
64 static int
65 load(struct module *module, int cmd, void *arg)
66 {
67 	int error = 0;
68 
69 	switch (cmd) {
70 	case MOD_LOAD :
71 		printf("syscall loaded at %d\n", offset);
72 		break;
73 	case MOD_UNLOAD :
74 		printf("syscall unloaded from %d\n", offset);
75 		break;
76 	default :
77 		error = EOPNOTSUPP;
78 		break;
79 	}
80 	return (error);
81 }
82 
83 SYSCALL_MODULE(syscall, &offset, &hello_sysent, load, NULL);
84