sys/vm/vm_unix.c

   1 /*
   2  * (MPSAFE)
   3  *
   4  * Copyright (c) 1988 University of Utah.
   5  * Copyright (c) 1991, 1993
   6  *      The Regents of the University of California.  All rights reserved.
   7  *
   8  * This code is derived from software contributed to Berkeley by
   9  * the Systems Programming Group of the University of Utah Computer
  10  * Science Department.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * from: Utah $Hdr: vm_unix.c 1.1 89/11/07$
  37  *
  38  *      @(#)vm_unix.c   8.1 (Berkeley) 6/11/93
  39  * $FreeBSD: src/sys/vm/vm_unix.c,v 1.24.2.2 2002/07/02 20:06:19 dillon Exp $
  40  * $DragonFly: src/sys/vm/vm_unix.c,v 1.7 2006/11/07 17:51:24 dillon Exp $
  41  */
  42
  43 /*
  44  * Traditional sbrk/grow interface to VM
  45  */
  46 #include <sys/param.h>
  47 #include <sys/sysproto.h>
  48 #include <sys/proc.h>
  49 #include <sys/resourcevar.h>
  50
  51 #include <vm/vm.h>
  52 #include <vm/vm_param.h>
  53 #include <sys/lock.h>
  54 #include <vm/pmap.h>
  55 #include <vm/vm_map.h>
  56
  57 #include <sys/thread.h>
  58
  59 /*
  60  * sys_obreak backs the C library sbrk call
  61  *
  62  * obreak_args(char *nsize)
  63  *
  64  * No requirements.
  65  */
  66 int
  67 sys_obreak(struct obreak_args *uap)
  68 {
  69         struct proc *p = curproc;
  70         struct vmspace *vm = p->p_vmspace;
  71         vm_offset_t new, old, base;
  72         int rv;
  73         int error;
  74
  75         error = 0;
  76
  77         lwkt_gettoken(&vm->vm_map.token);
  78
  79         base = round_page((vm_offset_t)vm->vm_daddr);
  80         new = round_page((vm_offset_t)uap->nsize);
  81         old = base + ctob(vm->vm_dsize);
  82
  83         if (new > base) {
  84                 /*
  85                  * We check resource limits here, but alow processes to
  86                  * reduce their usage, even if they remain over the limit.
  87                  */
  88                 if (new > old &&
  89                     (new - base) > (vm_offset_t) p->p_rlimit[RLIMIT_DATA].rlim_cur) {
  90                         error = ENOMEM;
  91                         goto done;
  92                 }
  93                 if (new >= VM_MAX_USER_ADDRESS) {
  94                         error = ENOMEM;
  95                         goto done;
  96                 }
  97         } else if (new < base) {
  98                 /*
  99                  * This is simply an invalid value.  If someone wants to
 100                  * do fancy address space manipulations, mmap and munmap
 101                  * can do most of what the user would want.
 102                  */
 103                 error = EINVAL;
 104                 goto done;
 105         }
 106
 107         if (new > old) {
 108                 vm_size_t diff;
 109
 110                 diff = new - old;
 111                 if (vm->vm_map.size + diff > p->p_rlimit[RLIMIT_VMEM].rlim_cur) {
 112                         error = ENOMEM;
 113                         goto done;
 114                 }
 115                 rv = vm_map_find(&vm->vm_map, NULL, NULL,
 116                                  0, &old, diff,
 117                                  PAGE_SIZE, FALSE,
 118                                  VM_MAPTYPE_NORMAL, VM_SUBSYS_BRK,
 119                                  VM_PROT_ALL, VM_PROT_ALL, 0);
 120                 if (rv != KERN_SUCCESS) {
 121                         error = ENOMEM;
 122                         goto done;
 123                 }
 124                 if (vm->vm_map.flags & MAP_WIREFUTURE)
 125                         vm_map_wire(&vm->vm_map, old, new, FALSE);
 126
 127                 vm->vm_dsize += btoc(diff);
 128         } else if (new < old) {
 129                 rv = vm_map_remove(&vm->vm_map, new, old);
 130                 if (rv != KERN_SUCCESS) {
 131                         error = ENOMEM;
 132                         goto done;
 133                 }
 134                 vm->vm_dsize -= btoc(old - new);
 135         }
 136 done:
 137         lwkt_reltoken(&vm->vm_map.token);
 138
 139         return (error);
 140 }