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/lock.h> 34 #include <sys/mutex.h> 35 #include <sys/sx.h> 36 #include <sys/module.h> 37 38 /* 39 * Acts like "nosys" but can be identified in sysent for dynamic call 40 * number assignment for a limited number of calls. 41 * 42 * Place holder for system call slots reserved for loadable modules. 43 */ 44 int 45 lkmnosys(struct thread *td, struct nosys_args *args) 46 { 47 return(nosys(td, args)); 48 } 49 50 int 51 lkmressys(struct thread *td, struct nosys_args *args) 52 { 53 return(nosys(td, args)); 54 } 55 56 int 57 syscall_register(int *offset, struct sysent *new_sysent, 58 struct sysent *old_sysent) 59 { 60 if (*offset == NO_SYSCALL) { 61 int i; 62 63 for (i = 1; i < SYS_MAXSYSCALL; ++i) 64 if (sysent[i].sy_call == (sy_call_t *)lkmnosys) 65 break; 66 if (i == SYS_MAXSYSCALL) 67 return ENFILE; 68 *offset = i; 69 } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL) 70 return EINVAL; 71 else if (sysent[*offset].sy_call != (sy_call_t *)lkmnosys && 72 sysent[*offset].sy_call != (sy_call_t *)lkmressys) 73 return EEXIST; 74 75 *old_sysent = sysent[*offset]; 76 sysent[*offset] = *new_sysent; 77 return 0; 78 } 79 80 int 81 syscall_deregister(int *offset, struct sysent *old_sysent) 82 { 83 if (*offset) 84 sysent[*offset] = *old_sysent; 85 return 0; 86 } 87 88 int 89 syscall_module_handler(struct module *mod, int what, void *arg) 90 { 91 struct syscall_module_data *data = (struct syscall_module_data*)arg; 92 modspecific_t ms; 93 int error; 94 95 switch (what) { 96 case MOD_LOAD : 97 error = syscall_register(data->offset, data->new_sysent, 98 &data->old_sysent); 99 if (error) 100 return error; 101 ms.intval = *data->offset; 102 MOD_XLOCK; 103 module_setspecific(mod, &ms); 104 MOD_XUNLOCK; 105 if (data->chainevh) 106 error = data->chainevh(mod, what, data->chainarg); 107 return error; 108 109 case MOD_UNLOAD : 110 if (data->chainevh) { 111 error = data->chainevh(mod, what, data->chainarg); 112 if (error) 113 return error; 114 } 115 error = syscall_deregister(data->offset, &data->old_sysent); 116 return error; 117 } 118 119 if (data->chainevh) 120 return data->chainevh(mod, what, data->chainarg); 121 else 122 return 0; 123 } 124