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
sys_sbrk(struct sysmsg * sysmsg,const struct sbrk_args * uap)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
sys_obreak(struct sysmsg * sysmsg,const struct obreak_args * uap)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 }
254