kern_syscalls.c

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    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: releng/5.0/sys/kern/kern_syscalls.c 92547 2002-03-18 07:45:30Z arr $
   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 }

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FreeBSD/Linux Kernel Cross Reference sys/kern/kern_syscalls.c

FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_syscalls.c