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: src/sys/kern/kern_syscalls.c,v 1.6 1999/10/11 15:19:10 peter Exp $ 27 * $DragonFly: src/sys/kern/kern_syscalls.c,v 1.4 2006/06/05 07:26:10 dillon Exp $ 28 */ 29 30 #include <sys/param.h> 31 #include <sys/sysproto.h> 32 #include <sys/sysent.h> 33 #include <sys/syscall.h> 34 #include <sys/module.h> 35 36 /* 37 * Acts like "nosys" but can be identified in sysent for dynamic call 38 * number assignment for a limited number of calls. 39 * 40 * Place holder for system call slots reserved for loadable modules. 41 */ 42 int 43 sys_lkmnosys(struct nosys_args *args) 44 { 45 return(sys_nosys(args)); 46 } 47 48 int 49 syscall_register(int *offset, struct sysent *new_sysent, 50 struct sysent *old_sysent) 51 { 52 if (*offset == NO_SYSCALL) { 53 int i; 54 55 for (i = 1; i < SYS_MAXSYSCALL; ++i) 56 if (sysent[i].sy_call == (sy_call_t *)sys_lkmnosys) 57 break; 58 if (i == SYS_MAXSYSCALL) 59 return ENFILE; 60 *offset = i; 61 } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL) 62 return EINVAL; 63 else if (sysent[*offset].sy_call != (sy_call_t *)sys_lkmnosys) 64 return EEXIST; 65 66 *old_sysent = sysent[*offset]; 67 sysent[*offset] = *new_sysent; 68 return 0; 69 } 70 71 int 72 syscall_deregister(int *offset, struct sysent *old_sysent) 73 { 74 if (*offset) 75 sysent[*offset] = *old_sysent; 76 return 0; 77 } 78 79 int 80 syscall_module_handler(struct module *mod, int what, void *arg) 81 { 82 struct syscall_module_data *data = (struct syscall_module_data*)arg; 83 modspecific_t ms; 84 int error; 85 86 switch (what) { 87 case MOD_LOAD : 88 error = syscall_register(data->offset, data->new_sysent, 89 &data->old_sysent); 90 if (error) 91 return error; 92 ms.intval = *data->offset; 93 module_setspecific(mod, &ms); 94 if (data->chainevh) 95 error = data->chainevh(mod, what, data->chainarg); 96 return error; 97 98 case MOD_UNLOAD : 99 if (data->chainevh) { 100 error = data->chainevh(mod, what, data->chainarg); 101 if (error) 102 return error; 103 } 104 error = syscall_deregister(data->offset, &data->old_sysent); 105 return error; 106 } 107 108 if (data->chainevh) 109 return data->chainevh(mod, what, data->chainarg); 110 else 111 return 0; 112 } 113