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