FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_kern.c
1 /*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * The Mach Operating System project at Carnegie-Mellon University.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 *
32 * from: @(#)vm_kern.c 8.3 (Berkeley) 1/12/94
33 *
34 *
35 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
36 * All rights reserved.
37 *
38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
39 *
40 * Permission to use, copy, modify and distribute this software and
41 * its documentation is hereby granted, provided that both the copyright
42 * notice and this permission notice appear in all copies of the
43 * software, derivative works or modified versions, and any portions
44 * thereof, and that both notices appear in supporting documentation.
45 *
46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
49 *
50 * Carnegie Mellon requests users of this software to return to
51 *
52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
53 * School of Computer Science
54 * Carnegie Mellon University
55 * Pittsburgh PA 15213-3890
56 *
57 * any improvements or extensions that they make and grant Carnegie the
58 * rights to redistribute these changes.
59 */
60
61 /*
62 * Kernel memory management.
63 */
64
65 #include <sys/cdefs.h>
66 __FBSDID("$FreeBSD: releng/7.4/sys/vm/vm_kern.c 212437 2010-09-10 21:53:47Z mdf $");
67
68 #include <sys/param.h>
69 #include <sys/systm.h>
70 #include <sys/kernel.h> /* for ticks and hz */
71 #include <sys/eventhandler.h>
72 #include <sys/lock.h>
73 #include <sys/mutex.h>
74 #include <sys/proc.h>
75 #include <sys/malloc.h>
76
77 #include <vm/vm.h>
78 #include <vm/vm_param.h>
79 #include <vm/pmap.h>
80 #include <vm/vm_map.h>
81 #include <vm/vm_object.h>
82 #include <vm/vm_page.h>
83 #include <vm/vm_pageout.h>
84 #include <vm/vm_extern.h>
85 #include <vm/uma.h>
86
87 vm_map_t kernel_map=0;
88 vm_map_t kmem_map=0;
89 vm_map_t exec_map=0;
90 vm_map_t pipe_map;
91 vm_map_t buffer_map=0;
92
93 /*
94 * kmem_alloc_nofault:
95 *
96 * Allocate a virtual address range with no underlying object and
97 * no initial mapping to physical memory. Any mapping from this
98 * range to physical memory must be explicitly created prior to
99 * its use, typically with pmap_qenter(). Any attempt to create
100 * a mapping on demand through vm_fault() will result in a panic.
101 */
102 vm_offset_t
103 kmem_alloc_nofault(map, size)
104 vm_map_t map;
105 vm_size_t size;
106 {
107 vm_offset_t addr;
108 int result;
109
110 size = round_page(size);
111 addr = vm_map_min(map);
112 result = vm_map_find(map, NULL, 0, &addr, size, VMFS_ANY_SPACE,
113 VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
114 if (result != KERN_SUCCESS) {
115 return (0);
116 }
117 return (addr);
118 }
119
120 /*
121 * Allocate wired-down memory in the kernel's address map
122 * or a submap.
123 */
124 vm_offset_t
125 kmem_alloc(map, size)
126 vm_map_t map;
127 vm_size_t size;
128 {
129 vm_offset_t addr;
130 vm_offset_t offset;
131 vm_offset_t i;
132
133 size = round_page(size);
134
135 /*
136 * Use the kernel object for wired-down kernel pages. Assume that no
137 * region of the kernel object is referenced more than once.
138 */
139
140 /*
141 * Locate sufficient space in the map. This will give us the final
142 * virtual address for the new memory, and thus will tell us the
143 * offset within the kernel map.
144 */
145 vm_map_lock(map);
146 if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
147 vm_map_unlock(map);
148 return (0);
149 }
150 offset = addr - VM_MIN_KERNEL_ADDRESS;
151 vm_object_reference(kernel_object);
152 vm_map_insert(map, kernel_object, offset, addr, addr + size,
153 VM_PROT_ALL, VM_PROT_ALL, 0);
154 vm_map_unlock(map);
155
156 /*
157 * Guarantee that there are pages already in this object before
158 * calling vm_map_wire. This is to prevent the following
159 * scenario:
160 *
161 * 1) Threads have swapped out, so that there is a pager for the
162 * kernel_object. 2) The kmsg zone is empty, and so we are
163 * kmem_allocing a new page for it. 3) vm_map_wire calls vm_fault;
164 * there is no page, but there is a pager, so we call
165 * pager_data_request. But the kmsg zone is empty, so we must
166 * kmem_alloc. 4) goto 1 5) Even if the kmsg zone is not empty: when
167 * we get the data back from the pager, it will be (very stale)
168 * non-zero data. kmem_alloc is defined to return zero-filled memory.
169 *
170 * We're intentionally not activating the pages we allocate to prevent a
171 * race with page-out. vm_map_wire will wire the pages.
172 */
173 VM_OBJECT_LOCK(kernel_object);
174 for (i = 0; i < size; i += PAGE_SIZE) {
175 vm_page_t mem;
176
177 mem = vm_page_grab(kernel_object, OFF_TO_IDX(offset + i),
178 VM_ALLOC_NOBUSY | VM_ALLOC_ZERO | VM_ALLOC_RETRY);
179 mem->valid = VM_PAGE_BITS_ALL;
180 KASSERT((mem->flags & PG_UNMANAGED) != 0,
181 ("kmem_alloc: page %p is managed", mem));
182 }
183 VM_OBJECT_UNLOCK(kernel_object);
184
185 /*
186 * And finally, mark the data as non-pageable.
187 */
188 (void) vm_map_wire(map, addr, addr + size,
189 VM_MAP_WIRE_SYSTEM|VM_MAP_WIRE_NOHOLES);
190
191 return (addr);
192 }
193
194 /*
195 * kmem_free:
196 *
197 * Release a region of kernel virtual memory allocated
198 * with kmem_alloc, and return the physical pages
199 * associated with that region.
200 *
201 * This routine may not block on kernel maps.
202 */
203 void
204 kmem_free(map, addr, size)
205 vm_map_t map;
206 vm_offset_t addr;
207 vm_size_t size;
208 {
209
210 (void) vm_map_remove(map, trunc_page(addr), round_page(addr + size));
211 }
212
213 /*
214 * kmem_suballoc:
215 *
216 * Allocates a map to manage a subrange
217 * of the kernel virtual address space.
218 *
219 * Arguments are as follows:
220 *
221 * parent Map to take range from
222 * min, max Returned endpoints of map
223 * size Size of range to find
224 * superpage_align Request that min is superpage aligned
225 */
226 vm_map_t
227 kmem_suballoc(vm_map_t parent, vm_offset_t *min, vm_offset_t *max,
228 vm_size_t size, boolean_t superpage_align)
229 {
230 int ret;
231 vm_map_t result;
232
233 size = round_page(size);
234
235 *min = vm_map_min(parent);
236 ret = vm_map_find(parent, NULL, 0, min, size, superpage_align ?
237 VMFS_ALIGNED_SPACE : VMFS_ANY_SPACE, VM_PROT_ALL, VM_PROT_ALL, 0);
238 if (ret != KERN_SUCCESS) {
239 printf("kmem_suballoc: bad status return of %d.\n", ret);
240 panic("kmem_suballoc");
241 }
242 *max = *min + size;
243 result = vm_map_create(vm_map_pmap(parent), *min, *max);
244 if (result == NULL)
245 panic("kmem_suballoc: cannot create submap");
246 if (vm_map_submap(parent, *min, *max, result) != KERN_SUCCESS)
247 panic("kmem_suballoc: unable to change range to submap");
248 return (result);
249 }
250
251 /*
252 * kmem_malloc:
253 *
254 * Allocate wired-down memory in the kernel's address map for the higher
255 * level kernel memory allocator (kern/kern_malloc.c). We cannot use
256 * kmem_alloc() because we may need to allocate memory at interrupt
257 * level where we cannot block (canwait == FALSE).
258 *
259 * This routine has its own private kernel submap (kmem_map) and object
260 * (kmem_object). This, combined with the fact that only malloc uses
261 * this routine, ensures that we will never block in map or object waits.
262 *
263 * We don't worry about expanding the map (adding entries) since entries
264 * for wired maps are statically allocated.
265 *
266 * `map' is ONLY allowed to be kmem_map or one of the mbuf submaps to
267 * which we never free.
268 */
269 vm_offset_t
270 kmem_malloc(map, size, flags)
271 vm_map_t map;
272 vm_size_t size;
273 int flags;
274 {
275 vm_offset_t addr;
276 int i, rv;
277
278 size = round_page(size);
279 addr = vm_map_min(map);
280
281 /*
282 * Locate sufficient space in the map. This will give us the final
283 * virtual address for the new memory, and thus will tell us the
284 * offset within the kernel map.
285 */
286 vm_map_lock(map);
287 if (vm_map_findspace(map, vm_map_min(map), size, &addr)) {
288 vm_map_unlock(map);
289 if ((flags & M_NOWAIT) == 0) {
290 for (i = 0; i < 8; i++) {
291 EVENTHANDLER_INVOKE(vm_lowmem, 0);
292 uma_reclaim();
293 vm_map_lock(map);
294 if (vm_map_findspace(map, vm_map_min(map),
295 size, &addr) == 0) {
296 break;
297 }
298 vm_map_unlock(map);
299 tsleep(&i, 0, "nokva", (hz / 4) * (i + 1));
300 }
301 if (i == 8) {
302 panic("kmem_malloc(%ld): kmem_map too small: %ld total allocated",
303 (long)size, (long)map->size);
304 }
305 } else {
306 return (0);
307 }
308 }
309
310 rv = kmem_back(map, addr, size, flags);
311 vm_map_unlock(map);
312 return (rv == KERN_SUCCESS ? addr : 0);
313 }
314
315 /*
316 * kmem_back:
317 *
318 * Allocate physical pages for the specified virtual address range.
319 */
320 int
321 kmem_back(vm_map_t map, vm_offset_t addr, vm_size_t size, int flags)
322 {
323 vm_offset_t offset, i;
324 vm_map_entry_t entry;
325 vm_page_t m;
326 int pflags;
327
328 /*
329 * XXX the map must be locked for write on entry, but there's
330 * no easy way to assert that.
331 */
332
333 offset = addr - VM_MIN_KERNEL_ADDRESS;
334 vm_object_reference(kmem_object);
335 vm_map_insert(map, kmem_object, offset, addr, addr + size,
336 VM_PROT_ALL, VM_PROT_ALL, 0);
337
338 if ((flags & (M_NOWAIT|M_USE_RESERVE)) == M_NOWAIT)
339 pflags = VM_ALLOC_INTERRUPT | VM_ALLOC_WIRED;
340 else
341 pflags = VM_ALLOC_SYSTEM | VM_ALLOC_WIRED;
342
343 if (flags & M_ZERO)
344 pflags |= VM_ALLOC_ZERO;
345
346 VM_OBJECT_LOCK(kmem_object);
347 for (i = 0; i < size; i += PAGE_SIZE) {
348 retry:
349 m = vm_page_alloc(kmem_object, OFF_TO_IDX(offset + i), pflags);
350
351 /*
352 * Ran out of space, free everything up and return. Don't need
353 * to lock page queues here as we know that the pages we got
354 * aren't on any queues.
355 */
356 if (m == NULL) {
357 if ((flags & M_NOWAIT) == 0) {
358 VM_OBJECT_UNLOCK(kmem_object);
359 vm_map_unlock(map);
360 VM_WAIT;
361 vm_map_lock(map);
362 VM_OBJECT_LOCK(kmem_object);
363 goto retry;
364 }
365 /*
366 * Free the pages before removing the map entry.
367 * They are already marked busy. Calling
368 * vm_map_delete before the pages has been freed or
369 * unbusied will cause a deadlock.
370 */
371 while (i != 0) {
372 i -= PAGE_SIZE;
373 m = vm_page_lookup(kmem_object,
374 OFF_TO_IDX(offset + i));
375 vm_page_lock_queues();
376 vm_page_unwire(m, 0);
377 vm_page_free(m);
378 vm_page_unlock_queues();
379 }
380 VM_OBJECT_UNLOCK(kmem_object);
381 vm_map_delete(map, addr, addr + size);
382 return (KERN_NO_SPACE);
383 }
384 if (flags & M_ZERO && (m->flags & PG_ZERO) == 0)
385 pmap_zero_page(m);
386 m->valid = VM_PAGE_BITS_ALL;
387 KASSERT((m->flags & PG_UNMANAGED) != 0,
388 ("kmem_malloc: page %p is managed", m));
389 }
390 VM_OBJECT_UNLOCK(kmem_object);
391
392 /*
393 * Mark map entry as non-pageable. Assert: vm_map_insert() will never
394 * be able to extend the previous entry so there will be a new entry
395 * exactly corresponding to this address range and it will have
396 * wired_count == 0.
397 */
398 if (!vm_map_lookup_entry(map, addr, &entry) ||
399 entry->start != addr || entry->end != addr + size ||
400 entry->wired_count != 0)
401 panic("kmem_malloc: entry not found or misaligned");
402 entry->wired_count = 1;
403
404 /*
405 * At this point, the kmem_object must be unlocked because
406 * vm_map_simplify_entry() calls vm_object_deallocate(), which
407 * locks the kmem_object.
408 */
409 vm_map_simplify_entry(map, entry);
410
411 /*
412 * Loop thru pages, entering them in the pmap.
413 */
414 VM_OBJECT_LOCK(kmem_object);
415 for (i = 0; i < size; i += PAGE_SIZE) {
416 m = vm_page_lookup(kmem_object, OFF_TO_IDX(offset + i));
417 /*
418 * Because this is kernel_pmap, this call will not block.
419 */
420 pmap_enter(kernel_pmap, addr + i, VM_PROT_ALL, m, VM_PROT_ALL,
421 TRUE);
422 vm_page_wakeup(m);
423 }
424 VM_OBJECT_UNLOCK(kmem_object);
425
426 return (KERN_SUCCESS);
427 }
428
429 /*
430 * kmem_alloc_wait:
431 *
432 * Allocates pageable memory from a sub-map of the kernel. If the submap
433 * has no room, the caller sleeps waiting for more memory in the submap.
434 *
435 * This routine may block.
436 */
437 vm_offset_t
438 kmem_alloc_wait(map, size)
439 vm_map_t map;
440 vm_size_t size;
441 {
442 vm_offset_t addr;
443
444 size = round_page(size);
445
446 for (;;) {
447 /*
448 * To make this work for more than one map, use the map's lock
449 * to lock out sleepers/wakers.
450 */
451 vm_map_lock(map);
452 if (vm_map_findspace(map, vm_map_min(map), size, &addr) == 0)
453 break;
454 /* no space now; see if we can ever get space */
455 if (vm_map_max(map) - vm_map_min(map) < size) {
456 vm_map_unlock(map);
457 return (0);
458 }
459 map->needs_wakeup = TRUE;
460 vm_map_unlock_and_wait(map, FALSE);
461 }
462 vm_map_insert(map, NULL, 0, addr, addr + size, VM_PROT_ALL, VM_PROT_ALL, 0);
463 vm_map_unlock(map);
464 return (addr);
465 }
466
467 /*
468 * kmem_free_wakeup:
469 *
470 * Returns memory to a submap of the kernel, and wakes up any processes
471 * waiting for memory in that map.
472 */
473 void
474 kmem_free_wakeup(map, addr, size)
475 vm_map_t map;
476 vm_offset_t addr;
477 vm_size_t size;
478 {
479
480 vm_map_lock(map);
481 (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size));
482 if (map->needs_wakeup) {
483 map->needs_wakeup = FALSE;
484 vm_map_wakeup(map);
485 }
486 vm_map_unlock(map);
487 }
488
489 /*
490 * kmem_init:
491 *
492 * Create the kernel map; insert a mapping covering kernel text,
493 * data, bss, and all space allocated thus far (`boostrap' data). The
494 * new map will thus map the range between VM_MIN_KERNEL_ADDRESS and
495 * `start' as allocated, and the range between `start' and `end' as free.
496 */
497 void
498 kmem_init(start, end)
499 vm_offset_t start, end;
500 {
501 vm_map_t m;
502
503 m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end);
504 m->system_map = 1;
505 vm_map_lock(m);
506 /* N.B.: cannot use kgdb to debug, starting with this assignment ... */
507 kernel_map = m;
508 (void) vm_map_insert(m, NULL, (vm_ooffset_t) 0,
509 #ifdef __amd64__
510 KERNBASE,
511 #else
512 VM_MIN_KERNEL_ADDRESS,
513 #endif
514 start, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
515 /* ... and ending with the completion of the above `insert' */
516 vm_map_unlock(m);
517 }
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