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/sysmsg.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_sbrk backs the C library sbrk call
  61  *
  62  * void *sbrk(intptr_t incr)
  63  *
  64  * No requirements.
  65  */
  66 int
  67 sys_sbrk(struct sysmsg *sysmsg, const struct sbrk_args *uap)
  68 {
  69         struct proc *p = curproc;
  70         struct vmspace *vm = p->p_vmspace;
  71         vm_offset_t nbase;
  72         vm_offset_t base;
  73         vm_offset_t base_end;
  74         vm_offset_t incr;
  75         int rv;
  76         int error;
  77
  78         error = 0;
  79
  80         lwkt_gettoken(&vm->vm_map.token);
  81
  82         /*
  83          * Cannot assume that last data page for binary is mapped R/W.
  84          */
  85         base = round_page((vm_offset_t)vm->vm_daddr) + vm->vm_dsize;
  86         incr = uap->incr;
  87
  88         /*
  89          * Cannot allow space to be freed with sbrk() because it is not
  90          * thread-safe for userland and because unrelated mmap()s can reside
  91          * in the data space if the DATA rlimit is raised on the running
  92          * program.
  93          */
  94         if (incr < 0) {
  95                 error = EOPNOTSUPP;
  96                 goto done;
  97         }
  98
  99         /*
 100          * Userland requests current base
 101          */
 102         if (incr == 0) {
 103                 sysmsg->sysmsg_resultp = (void *)base;
 104                 goto done;
 105         }
 106
 107         /*
 108          * Calculate approximate area (vm_map_find() may change this).
 109          * Check for overflow, address space, and rlimit caps.
 110          */
 111         base_end = base + incr;
 112         if (base_end >= VM_MAX_USER_ADDRESS) {
 113                 error = ENOMEM;
 114                 goto done;
 115         }
 116         if (base_end < base ||
 117             base_end - (vm_offset_t)vm->vm_daddr >
 118             (vm_offset_t)p->p_rlimit[RLIMIT_DATA].rlim_cur) {
 119                 error = ENOMEM;
 120                 goto done;
 121         }
 122
 123         /*
 124          * Same-page optimization (protected by token)
 125          */
 126         if ((base & PAGE_MASK) != 0 &&
 127             ((base ^ (base_end - 1)) & ~(vm_offset_t)PAGE_MASK) == 0) {
 128                 sysmsg->sysmsg_resultp = (void *)base;
 129                 vm->vm_dsize += incr;
 130                 goto done;
 131         }
 132
 133         /*
 134          * Formally map more space
 135          */
 136         nbase = round_page(base);
 137         rv = vm_map_find(&vm->vm_map, NULL, NULL,
 138                          0, &nbase, round_page(incr),
 139                          PAGE_SIZE, FALSE,
 140                          VM_MAPTYPE_NORMAL, VM_SUBSYS_BRK,
 141                          VM_PROT_ALL, VM_PROT_ALL, 0);
 142         if (rv != KERN_SUCCESS) {
 143                 error = ENOMEM;
 144                 goto done;
 145         }
 146         base_end = nbase + round_page(incr);
 147         sysmsg->sysmsg_resultp = (void *)nbase;
 148
 149         /* wire the pages */
 150         if (vm->vm_map.flags & MAP_WIREFUTURE)
 151                 vm_map_kernel_wiring(&vm->vm_map, base, base_end, 0);
 152
 153         /*
 154          * Adjust dsize upwards only
 155          */
 156         incr = nbase + incr - round_page((vm_offset_t)vm->vm_daddr);
 157         if (vm->vm_dsize < incr)
 158                 vm->vm_dsize = incr;
 159
 160 done:
 161         lwkt_reltoken(&vm->vm_map.token);
 162
 163         return (error);
 164 }
 165
 166 /*
 167  * sys_obreak is used by the sbrk emulation code in libc when sbrk()
 168  * is not supported.
 169  *
 170  * obreak_args(char *nsize)
 171  *
 172  * No requirements.
 173  */
 174 int
 175 sys_obreak(struct sysmsg *sysmsg, const struct obreak_args *uap)
 176 {
 177         struct proc *p = curproc;
 178         struct vmspace *vm = p->p_vmspace;
 179         vm_offset_t new, old, base;
 180         int rv;
 181         int error;
 182
 183         error = 0;
 184
 185         lwkt_gettoken(&vm->vm_map.token);
 186
 187         base = round_page((vm_offset_t)vm->vm_daddr);
 188         new = round_page((vm_offset_t)uap->nsize);
 189         old = base + round_page(vm->vm_dsize);
 190
 191         if (new > base) {
 192                 /*
 193                  * We check resource limits here, but alow processes to
 194                  * reduce their usage, even if they remain over the limit.
 195                  */
 196                 if (new > old &&
 197                     (new - base) > (vm_offset_t) p->p_rlimit[RLIMIT_DATA].rlim_cur) {
 198                         error = ENOMEM;
 199                         goto done;
 200                 }
 201                 if (new >= VM_MAX_USER_ADDRESS) {
 202                         error = ENOMEM;
 203                         goto done;
 204                 }
 205         } else if (new < base) {
 206                 /*
 207                  * This is simply an invalid value.  If someone wants to
 208                  * do fancy address space manipulations, mmap and munmap
 209                  * can do most of what the user would want.
 210                  */
 211                 error = EINVAL;
 212                 goto done;
 213         }
 214
 215         if (new > old) {
 216                 vm_size_t diff;
 217
 218                 diff = new - old;
 219                 if (vm->vm_map.size + diff > p->p_rlimit[RLIMIT_VMEM].rlim_cur) {
 220                         error = ENOMEM;
 221                         goto done;
 222                 }
 223                 rv = vm_map_find(&vm->vm_map, NULL, NULL,
 224                                  0, &old, diff,
 225                                  PAGE_SIZE, FALSE,
 226                                  VM_MAPTYPE_NORMAL, VM_SUBSYS_BRK,
 227                                  VM_PROT_ALL, VM_PROT_ALL, 0);
 228                 if (rv != KERN_SUCCESS) {
 229                         error = ENOMEM;
 230                         goto done;
 231                 }
 232
 233                 /* wire the pages */
 234                 if (vm->vm_map.flags & MAP_WIREFUTURE)
 235                         vm_map_kernel_wiring(&vm->vm_map, old, new, 0);
 236
 237                 vm->vm_dsize += diff;
 238         } else if (new < old) {
 239                 error = EOPNOTSUPP;
 240 #if 0
 241                 rv = vm_map_remove(&vm->vm_map, new, old);
 242                 if (rv != KERN_SUCCESS) {
 243                         error = ENOMEM;
 244                         goto done;
 245                 }
 246                 vm->vm_dsize -= old - new;
 247 #endif
 248         }
 249 done:
 250         lwkt_reltoken(&vm->vm_map.token);
 251
 252         return (error);
 253 }