The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]

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

Version: -  FREEBSD  -  FREEBSD-12-STABLE  -  FREEBSD-12-0  -  FREEBSD-11-STABLE  -  FREEBSD-11-2  -  FREEBSD-11-1  -  FREEBSD-11-0  -  FREEBSD-10-STABLE  -  FREEBSD-10-4  -  FREEBSD-10-3  -  FREEBSD-10-2  -  FREEBSD-10-1  -  FREEBSD-10-0  -  FREEBSD-9-STABLE  -  FREEBSD-9-3  -  FREEBSD-9-2  -  FREEBSD-9-1  -  FREEBSD-9-0  -  FREEBSD-8-STABLE  -  FREEBSD-8-4  -  FREEBSD-8-3  -  FREEBSD-8-2  -  FREEBSD-8-1  -  FREEBSD-8-0  -  FREEBSD-7-STABLE  -  FREEBSD-7-4  -  FREEBSD-7-3  -  FREEBSD-7-2  -  FREEBSD-7-1  -  FREEBSD-7-0  -  FREEBSD-6-STABLE  -  FREEBSD-6-4  -  FREEBSD-6-3  -  FREEBSD-6-2  -  FREEBSD-6-1  -  FREEBSD-6-0  -  FREEBSD-5-STABLE  -  FREEBSD-5-5  -  FREEBSD-5-4  -  FREEBSD-5-3  -  FREEBSD-5-2  -  FREEBSD-5-1  -  FREEBSD-5-0  -  FREEBSD-4-STABLE  -  FREEBSD-3-STABLE  -  FREEBSD22  -  linux-2.6  -  linux-2.4.22  -  MK83  -  MK84  -  PLAN9  -  DFBSD  -  NETBSD  -  NETBSD5  -  NETBSD4  -  NETBSD3  -  NETBSD20  -  OPENBSD  -  xnu-517  -  xnu-792  -  xnu-792.6.70  -  xnu-1228  -  xnu-1456.1.26  -  xnu-1699.24.8  -  xnu-2050.18.24  -  OPENSOLARIS  -  minix-3-1-1 
SearchContext: -  none  -  3  -  10 

    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 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD: stable/10/sys/kern/kern_syscalls.c 214181 2010-10-21 20:31:50Z delphij $");
   29 
   30 #include <sys/param.h>
   31 #include <sys/kernel.h>
   32 #include <sys/lock.h>
   33 #include <sys/module.h>
   34 #include <sys/sx.h>
   35 #include <sys/syscall.h>
   36 #include <sys/sysent.h>
   37 #include <sys/sysproto.h>
   38 #include <sys/systm.h>
   39 #include <machine/atomic.h>
   40 
   41 /*
   42  * Acts like "nosys" but can be identified in sysent for dynamic call
   43  * number assignment for a limited number of calls.
   44  *
   45  * Place holder for system call slots reserved for loadable modules.
   46  */
   47 int
   48 lkmnosys(struct thread *td, struct nosys_args *args)
   49 {
   50 
   51         return (nosys(td, args));
   52 }
   53 
   54 int
   55 lkmressys(struct thread *td, struct nosys_args *args)
   56 {
   57 
   58         return (nosys(td, args));
   59 }
   60 
   61 static void
   62 syscall_thread_drain(struct sysent *se)
   63 {
   64         u_int32_t cnt, oldcnt;
   65 
   66         do {
   67                 oldcnt = se->sy_thrcnt;
   68                 KASSERT((oldcnt & SY_THR_STATIC) == 0,
   69                     ("drain on static syscall"));
   70                 cnt = oldcnt | SY_THR_DRAINING;
   71         } while (atomic_cmpset_acq_32(&se->sy_thrcnt, oldcnt, cnt) == 0);
   72         while (atomic_cmpset_32(&se->sy_thrcnt, SY_THR_DRAINING,
   73             SY_THR_ABSENT) == 0)
   74                 pause("scdrn", hz/2);
   75 }
   76 
   77 int
   78 syscall_thread_enter(struct thread *td, struct sysent *se)
   79 {
   80         u_int32_t cnt, oldcnt;
   81 
   82         do {
   83                 oldcnt = se->sy_thrcnt;
   84                 if ((oldcnt & SY_THR_STATIC) != 0)
   85                         return (0);
   86                 if ((oldcnt & (SY_THR_DRAINING | SY_THR_ABSENT)) != 0)
   87                         return (ENOSYS);
   88                 cnt = oldcnt + SY_THR_INCR;
   89         } while (atomic_cmpset_acq_32(&se->sy_thrcnt, oldcnt, cnt) == 0);
   90         return (0);
   91 }
   92 
   93 void
   94 syscall_thread_exit(struct thread *td, struct sysent *se)
   95 {
   96         u_int32_t cnt, oldcnt;
   97 
   98         do {
   99                 oldcnt = se->sy_thrcnt;
  100                 if ((oldcnt & SY_THR_STATIC) != 0)
  101                         return;
  102                 cnt = oldcnt - SY_THR_INCR;
  103         } while (atomic_cmpset_rel_32(&se->sy_thrcnt, oldcnt, cnt) == 0);
  104 }
  105 
  106 int
  107 syscall_register(int *offset, struct sysent *new_sysent,
  108     struct sysent *old_sysent)
  109 {
  110         int i;
  111 
  112         if (*offset == NO_SYSCALL) {
  113                 for (i = 1; i < SYS_MAXSYSCALL; ++i)
  114                         if (sysent[i].sy_call == (sy_call_t *)lkmnosys)
  115                                 break;
  116                 if (i == SYS_MAXSYSCALL)
  117                         return (ENFILE);
  118                 *offset = i;
  119         } else if (*offset < 0 || *offset >= SYS_MAXSYSCALL)
  120                 return (EINVAL);
  121         else if (sysent[*offset].sy_call != (sy_call_t *)lkmnosys &&
  122             sysent[*offset].sy_call != (sy_call_t *)lkmressys)
  123                 return (EEXIST);
  124 
  125         KASSERT(sysent[*offset].sy_thrcnt == SY_THR_ABSENT,
  126             ("dynamic syscall is not protected"));
  127         *old_sysent = sysent[*offset];
  128         new_sysent->sy_thrcnt = SY_THR_ABSENT;
  129         sysent[*offset] = *new_sysent;
  130         atomic_store_rel_32(&sysent[*offset].sy_thrcnt, 0);
  131         return (0);
  132 }
  133 
  134 int
  135 syscall_deregister(int *offset, struct sysent *old_sysent)
  136 {
  137 
  138         if (*offset) {
  139                 syscall_thread_drain(&sysent[*offset]);
  140                 sysent[*offset] = *old_sysent;
  141         }
  142         return (0);
  143 }
  144 
  145 int
  146 syscall_module_handler(struct module *mod, int what, void *arg)
  147 {
  148         struct syscall_module_data *data = arg;
  149         modspecific_t ms;
  150         int error;
  151 
  152         switch (what) {
  153         case MOD_LOAD:
  154                 error = syscall_register(data->offset, data->new_sysent,
  155                     &data->old_sysent);
  156                 if (error) {
  157                         /* Leave a mark so we know to safely unload below. */
  158                         data->offset = NULL;
  159                         return (error);
  160                 }
  161                 ms.intval = *data->offset;
  162                 MOD_XLOCK;
  163                 module_setspecific(mod, &ms);
  164                 MOD_XUNLOCK;
  165                 if (data->chainevh)
  166                         error = data->chainevh(mod, what, data->chainarg);
  167                 return (error);
  168         case MOD_UNLOAD:
  169                 /*
  170                  * MOD_LOAD failed, so just return without calling the
  171                  * chained handler since we didn't pass along the MOD_LOAD
  172                  * event.
  173                  */
  174                 if (data->offset == NULL)
  175                         return (0);
  176                 if (data->chainevh) {
  177                         error = data->chainevh(mod, what, data->chainarg);
  178                         if (error)
  179                                 return error;
  180                 }
  181                 error = syscall_deregister(data->offset, &data->old_sysent);
  182                 return (error);
  183         default:
  184                 if (data->chainevh)
  185                         return (data->chainevh(mod, what, data->chainarg));
  186                 return (EOPNOTSUPP);
  187         }
  188 
  189         /* NOTREACHED */
  190 }
  191 
  192 int
  193 syscall_helper_register(struct syscall_helper_data *sd)
  194 {
  195         struct syscall_helper_data *sd1;
  196         int error;
  197 
  198         for (sd1 = sd; sd1->syscall_no != NO_SYSCALL; sd1++) {
  199                 error = syscall_register(&sd1->syscall_no, &sd1->new_sysent,
  200                     &sd1->old_sysent);
  201                 if (error != 0) {
  202                         syscall_helper_unregister(sd);
  203                         return (error);
  204                 }
  205                 sd1->registered = 1;
  206         }
  207         return (0);
  208 }
  209 
  210 int
  211 syscall_helper_unregister(struct syscall_helper_data *sd)
  212 {
  213         struct syscall_helper_data *sd1;
  214 
  215         for (sd1 = sd; sd1->registered != 0; sd1++) {
  216                 syscall_deregister(&sd1->syscall_no, &sd1->old_sysent);
  217                 sd1->registered = 0;
  218         }
  219         return (0);
  220 }

Cache object: 043675b687e0fc4bb36eac4513e4f857


[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]


This page is part of the FreeBSD/Linux Linux Kernel Cross-Reference, and was automatically generated using a modified version of the LXR engine.