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