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15637ed4 RG |
1 | /* |
2 | * Copyright (c) 1991 Regents of the University of California. | |
3 | * 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 | * 3. All advertising materials mentioning features or use of this software | |
17 | * must display the following acknowledgement: | |
18 | * This product includes software developed by the University of | |
19 | * California, Berkeley and its contributors. | |
20 | * 4. 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 | * | |
78ed81a3 | 36 | * from: @(#)vm_object.c 7.4 (Berkeley) 5/7/91 |
37 | * $Id$ | |
38 | */ | |
39 | ||
40 | /* | |
15637ed4 RG |
41 | * Copyright (c) 1987, 1990 Carnegie-Mellon University. |
42 | * All rights reserved. | |
43 | * | |
44 | * Authors: Avadis Tevanian, Jr., Michael Wayne Young | |
45 | * | |
46 | * Permission to use, copy, modify and distribute this software and | |
47 | * its documentation is hereby granted, provided that both the copyright | |
48 | * notice and this permission notice appear in all copies of the | |
49 | * software, derivative works or modified versions, and any portions | |
50 | * thereof, and that both notices appear in supporting documentation. | |
51 | * | |
52 | * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" | |
53 | * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND | |
54 | * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. | |
55 | * | |
56 | * Carnegie Mellon requests users of this software to return to | |
57 | * | |
58 | * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU | |
59 | * School of Computer Science | |
60 | * Carnegie Mellon University | |
61 | * Pittsburgh PA 15213-3890 | |
62 | * | |
63 | * any improvements or extensions that they make and grant Carnegie the | |
64 | * rights to redistribute these changes. | |
15637ed4 RG |
65 | */ |
66 | ||
67 | /* | |
68 | * Virtual memory object module. | |
69 | */ | |
70 | ||
78ed81a3 | 71 | #include "ddb.h" |
72 | ||
15637ed4 RG |
73 | #include "param.h" |
74 | #include "malloc.h" | |
75 | ||
76 | #include "vm.h" | |
77 | #include "vm_page.h" | |
78 | ||
79 | /* | |
80 | * Virtual memory objects maintain the actual data | |
81 | * associated with allocated virtual memory. A given | |
82 | * page of memory exists within exactly one object. | |
83 | * | |
84 | * An object is only deallocated when all "references" | |
85 | * are given up. Only one "reference" to a given | |
86 | * region of an object should be writeable. | |
87 | * | |
88 | * Associated with each object is a list of all resident | |
89 | * memory pages belonging to that object; this list is | |
90 | * maintained by the "vm_page" module, and locked by the object's | |
91 | * lock. | |
92 | * | |
93 | * Each object also records a "pager" routine which is | |
94 | * used to retrieve (and store) pages to the proper backing | |
95 | * storage. In addition, objects may be backed by other | |
96 | * objects from which they were virtual-copied. | |
97 | * | |
98 | * The only items within the object structure which are | |
99 | * modified after time of creation are: | |
100 | * reference count locked by object's lock | |
101 | * pager routine locked by object's lock | |
102 | * | |
103 | */ | |
104 | ||
105 | struct vm_object kernel_object_store; | |
106 | struct vm_object kmem_object_store; | |
107 | ||
108 | #define VM_OBJECT_HASH_COUNT 157 | |
109 | ||
110 | int vm_cache_max = 100; /* can patch if necessary */ | |
111 | queue_head_t vm_object_hashtable[VM_OBJECT_HASH_COUNT]; | |
112 | ||
113 | long object_collapses = 0; | |
114 | long object_bypasses = 0; | |
115 | ||
116 | /* | |
117 | * vm_object_init: | |
118 | * | |
119 | * Initialize the VM objects module. | |
120 | */ | |
121 | void vm_object_init() | |
122 | { | |
123 | register int i; | |
124 | ||
125 | queue_init(&vm_object_cached_list); | |
126 | queue_init(&vm_object_list); | |
127 | vm_object_count = 0; | |
128 | simple_lock_init(&vm_cache_lock); | |
129 | simple_lock_init(&vm_object_list_lock); | |
130 | ||
131 | for (i = 0; i < VM_OBJECT_HASH_COUNT; i++) | |
132 | queue_init(&vm_object_hashtable[i]); | |
133 | ||
134 | kernel_object = &kernel_object_store; | |
135 | _vm_object_allocate(VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS, | |
136 | kernel_object); | |
137 | ||
138 | kmem_object = &kmem_object_store; | |
139 | _vm_object_allocate(VM_KMEM_SIZE + VM_MBUF_SIZE, kmem_object); | |
140 | } | |
141 | ||
142 | /* | |
143 | * vm_object_allocate: | |
144 | * | |
145 | * Returns a new object with the given size. | |
146 | */ | |
147 | ||
148 | vm_object_t vm_object_allocate(size) | |
149 | vm_size_t size; | |
150 | { | |
151 | register vm_object_t result; | |
152 | ||
153 | result = (vm_object_t) | |
154 | malloc((u_long)sizeof *result, M_VMOBJ, M_WAITOK); | |
155 | ||
156 | _vm_object_allocate(size, result); | |
157 | ||
158 | return(result); | |
159 | } | |
160 | ||
161 | _vm_object_allocate(size, object) | |
162 | vm_size_t size; | |
163 | register vm_object_t object; | |
164 | { | |
165 | queue_init(&object->memq); | |
166 | vm_object_lock_init(object); | |
167 | object->ref_count = 1; | |
168 | object->resident_page_count = 0; | |
169 | object->size = size; | |
170 | object->can_persist = FALSE; | |
171 | object->paging_in_progress = 0; | |
172 | object->copy = NULL; | |
173 | ||
174 | /* | |
175 | * Object starts out read-write, with no pager. | |
176 | */ | |
177 | ||
178 | object->pager = NULL; | |
179 | object->pager_ready = FALSE; | |
180 | object->internal = TRUE; /* vm_allocate_with_pager will reset */ | |
181 | object->paging_offset = 0; | |
182 | object->shadow = NULL; | |
183 | object->shadow_offset = (vm_offset_t) 0; | |
184 | ||
185 | simple_lock(&vm_object_list_lock); | |
186 | queue_enter(&vm_object_list, object, vm_object_t, object_list); | |
187 | vm_object_count++; | |
188 | simple_unlock(&vm_object_list_lock); | |
189 | } | |
190 | ||
191 | /* | |
192 | * vm_object_reference: | |
193 | * | |
194 | * Gets another reference to the given object. | |
195 | */ | |
196 | void vm_object_reference(object) | |
197 | register vm_object_t object; | |
198 | { | |
199 | if (object == NULL) | |
200 | return; | |
201 | ||
202 | vm_object_lock(object); | |
203 | object->ref_count++; | |
204 | vm_object_unlock(object); | |
205 | } | |
206 | ||
207 | /* | |
208 | * vm_object_deallocate: | |
209 | * | |
210 | * Release a reference to the specified object, | |
211 | * gained either through a vm_object_allocate | |
212 | * or a vm_object_reference call. When all references | |
213 | * are gone, storage associated with this object | |
214 | * may be relinquished. | |
215 | * | |
216 | * No object may be locked. | |
217 | */ | |
218 | void vm_object_deallocate(object) | |
219 | register vm_object_t object; | |
220 | { | |
221 | vm_object_t temp; | |
222 | ||
223 | while (object != NULL) { | |
224 | ||
225 | /* | |
226 | * The cache holds a reference (uncounted) to | |
227 | * the object; we must lock it before removing | |
228 | * the object. | |
229 | */ | |
230 | ||
231 | vm_object_cache_lock(); | |
232 | ||
233 | /* | |
234 | * Lose the reference | |
235 | */ | |
236 | vm_object_lock(object); | |
237 | if (--(object->ref_count) != 0) { | |
238 | ||
239 | /* | |
240 | * If there are still references, then | |
241 | * we are done. | |
242 | */ | |
243 | vm_object_unlock(object); | |
244 | vm_object_cache_unlock(); | |
245 | return; | |
246 | } | |
247 | ||
248 | /* | |
249 | * See if this object can persist. If so, enter | |
250 | * it in the cache, then deactivate all of its | |
251 | * pages. | |
252 | */ | |
253 | ||
254 | if (object->can_persist) { | |
78ed81a3 | 255 | #ifdef DIAGNOSTIC |
15637ed4 RG |
256 | register vm_page_t p; |
257 | ||
258 | /* | |
259 | * Check for dirty pages in object | |
260 | * Print warning as this may signify kernel bugs | |
261 | * pk@cs.few.eur.nl - 4/15/93 | |
262 | */ | |
263 | p = (vm_page_t) queue_first(&object->memq); | |
264 | while (!queue_end(&object->memq, (queue_entry_t) p)) { | |
265 | VM_PAGE_CHECK(p); | |
266 | ||
267 | if (pmap_is_modified(VM_PAGE_TO_PHYS(p)) || | |
268 | !p->clean) { | |
269 | ||
270 | printf("vm_object_dealloc: persistent object %x isn't clean\n", object); | |
271 | goto cant_persist; | |
272 | } | |
273 | ||
274 | p = (vm_page_t) queue_next(&p->listq); | |
275 | } | |
78ed81a3 | 276 | #endif /* DIAGNOSTIC */ |
15637ed4 RG |
277 | |
278 | queue_enter(&vm_object_cached_list, object, | |
279 | vm_object_t, cached_list); | |
280 | vm_object_cached++; | |
281 | vm_object_cache_unlock(); | |
282 | ||
283 | vm_object_deactivate_pages(object); | |
284 | vm_object_unlock(object); | |
285 | ||
286 | vm_object_cache_trim(); | |
287 | return; | |
288 | } | |
289 | cant_persist:; | |
290 | ||
291 | /* | |
292 | * Make sure no one can look us up now. | |
293 | */ | |
294 | vm_object_remove(object->pager); | |
295 | vm_object_cache_unlock(); | |
296 | ||
297 | temp = object->shadow; | |
298 | vm_object_terminate(object); | |
299 | /* unlocks and deallocates object */ | |
300 | object = temp; | |
301 | } | |
302 | } | |
303 | ||
304 | ||
305 | /* | |
306 | * vm_object_terminate actually destroys the specified object, freeing | |
307 | * up all previously used resources. | |
308 | * | |
309 | * The object must be locked. | |
310 | */ | |
311 | void vm_object_terminate(object) | |
312 | register vm_object_t object; | |
313 | { | |
314 | register vm_page_t p; | |
315 | vm_object_t shadow_object; | |
316 | ||
317 | /* | |
318 | * Detach the object from its shadow if we are the shadow's | |
319 | * copy. | |
320 | */ | |
321 | if ((shadow_object = object->shadow) != NULL) { | |
322 | vm_object_lock(shadow_object); | |
323 | if (shadow_object->copy == object) | |
324 | shadow_object->copy = NULL; | |
325 | #if 0 | |
326 | else if (shadow_object->copy != NULL) | |
327 | panic("vm_object_terminate: copy/shadow inconsistency"); | |
328 | #endif | |
329 | vm_object_unlock(shadow_object); | |
330 | } | |
331 | ||
332 | /* | |
333 | * Wait until the pageout daemon is through | |
334 | * with the object. | |
335 | */ | |
336 | ||
337 | while (object->paging_in_progress != 0) { | |
338 | vm_object_sleep(object, object, FALSE); | |
339 | vm_object_lock(object); | |
340 | } | |
341 | ||
342 | ||
343 | /* | |
344 | * While the paging system is locked, | |
345 | * pull the object's pages off the active | |
346 | * and inactive queues. This keeps the | |
347 | * pageout daemon from playing with them | |
348 | * during vm_pager_deallocate. | |
349 | * | |
350 | * We can't free the pages yet, because the | |
351 | * object's pager may have to write them out | |
352 | * before deallocating the paging space. | |
353 | */ | |
354 | ||
355 | p = (vm_page_t) queue_first(&object->memq); | |
356 | while (!queue_end(&object->memq, (queue_entry_t) p)) { | |
357 | VM_PAGE_CHECK(p); | |
358 | ||
359 | vm_page_lock_queues(); | |
360 | if (p->active) { | |
361 | queue_remove(&vm_page_queue_active, p, vm_page_t, | |
362 | pageq); | |
363 | p->active = FALSE; | |
364 | vm_page_active_count--; | |
365 | } | |
366 | ||
367 | if (p->inactive) { | |
368 | queue_remove(&vm_page_queue_inactive, p, vm_page_t, | |
369 | pageq); | |
370 | p->inactive = FALSE; | |
371 | vm_page_inactive_count--; | |
372 | } | |
373 | vm_page_unlock_queues(); | |
374 | p = (vm_page_t) queue_next(&p->listq); | |
375 | } | |
376 | ||
377 | vm_object_unlock(object); | |
378 | ||
379 | if (object->paging_in_progress != 0) | |
380 | panic("vm_object_deallocate: pageout in progress"); | |
381 | ||
382 | /* | |
383 | * Clean and free the pages, as appropriate. | |
384 | * All references to the object are gone, | |
385 | * so we don't need to lock it. | |
386 | */ | |
387 | ||
388 | if (!object->internal) { | |
389 | vm_object_lock(object); | |
390 | vm_object_page_clean(object, 0, 0); | |
391 | vm_object_unlock(object); | |
392 | } | |
393 | while (!queue_empty(&object->memq)) { | |
394 | p = (vm_page_t) queue_first(&object->memq); | |
395 | ||
396 | VM_PAGE_CHECK(p); | |
397 | ||
398 | vm_page_lock_queues(); | |
399 | vm_page_free(p); | |
400 | vm_page_unlock_queues(); | |
401 | } | |
402 | ||
403 | /* | |
404 | * Let the pager know object is dead. | |
405 | */ | |
406 | ||
407 | if (object->pager != NULL) | |
408 | vm_pager_deallocate(object->pager); | |
409 | ||
410 | ||
411 | simple_lock(&vm_object_list_lock); | |
412 | queue_remove(&vm_object_list, object, vm_object_t, object_list); | |
413 | vm_object_count--; | |
414 | simple_unlock(&vm_object_list_lock); | |
415 | ||
416 | /* | |
417 | * Free the space for the object. | |
418 | */ | |
419 | ||
420 | free((caddr_t)object, M_VMOBJ); | |
421 | } | |
422 | ||
423 | /* | |
424 | * vm_object_page_clean | |
425 | * | |
426 | * Clean all dirty pages in the specified range of object. | |
427 | * Leaves page on whatever queue it is currently on. | |
428 | * | |
429 | * Odd semantics: if start == end, we clean everything. | |
430 | * | |
431 | * The object must be locked. | |
432 | */ | |
433 | vm_object_page_clean(object, start, end) | |
434 | register vm_object_t object; | |
435 | register vm_offset_t start; | |
436 | register vm_offset_t end; | |
437 | { | |
438 | register vm_page_t p; | |
439 | ||
440 | if (object->pager == NULL) | |
441 | return; | |
442 | ||
443 | again: | |
444 | p = (vm_page_t) queue_first(&object->memq); | |
445 | while (!queue_end(&object->memq, (queue_entry_t) p)) { | |
446 | if (start == end || | |
447 | p->offset >= start && p->offset < end) { | |
448 | if (p->clean && pmap_is_modified(VM_PAGE_TO_PHYS(p))) | |
449 | p->clean = FALSE; | |
450 | pmap_page_protect(VM_PAGE_TO_PHYS(p), VM_PROT_NONE); | |
451 | if (!p->clean) { | |
452 | p->busy = TRUE; | |
453 | object->paging_in_progress++; | |
454 | vm_object_unlock(object); | |
455 | (void) vm_pager_put(object->pager, p, TRUE); | |
456 | vm_object_lock(object); | |
457 | object->paging_in_progress--; | |
458 | p->busy = FALSE; | |
459 | PAGE_WAKEUP(p); | |
460 | goto again; | |
461 | } | |
462 | } | |
463 | p = (vm_page_t) queue_next(&p->listq); | |
464 | } | |
465 | } | |
466 | ||
467 | /* | |
468 | * vm_object_deactivate_pages | |
469 | * | |
470 | * Deactivate all pages in the specified object. (Keep its pages | |
471 | * in memory even though it is no longer referenced.) | |
472 | * | |
473 | * The object must be locked. | |
474 | */ | |
475 | vm_object_deactivate_pages(object) | |
476 | register vm_object_t object; | |
477 | { | |
478 | register vm_page_t p, next; | |
479 | ||
480 | p = (vm_page_t) queue_first(&object->memq); | |
481 | while (!queue_end(&object->memq, (queue_entry_t) p)) { | |
482 | next = (vm_page_t) queue_next(&p->listq); | |
483 | vm_page_lock_queues(); | |
78ed81a3 | 484 | if (!p->busy) |
485 | vm_page_deactivate(p); /* optimisation from mach 3.0 - | |
486 | * andrew@werple.apana.org.au, | |
487 | * Feb '93 | |
488 | */ | |
15637ed4 RG |
489 | vm_page_unlock_queues(); |
490 | p = next; | |
491 | } | |
492 | } | |
493 | ||
494 | /* | |
495 | * Trim the object cache to size. | |
496 | */ | |
497 | vm_object_cache_trim() | |
498 | { | |
499 | register vm_object_t object; | |
500 | ||
501 | vm_object_cache_lock(); | |
502 | while (vm_object_cached > vm_cache_max) { | |
503 | object = (vm_object_t) queue_first(&vm_object_cached_list); | |
504 | vm_object_cache_unlock(); | |
505 | ||
506 | if (object != vm_object_lookup(object->pager)) | |
507 | panic("vm_object_deactivate: I'm sooo confused."); | |
508 | ||
509 | pager_cache(object, FALSE); | |
510 | ||
511 | vm_object_cache_lock(); | |
512 | } | |
513 | vm_object_cache_unlock(); | |
514 | } | |
515 | ||
516 | ||
517 | /* | |
518 | * vm_object_shutdown() | |
519 | * | |
520 | * Shut down the object system. Unfortunately, while we | |
521 | * may be trying to do this, init is happily waiting for | |
522 | * processes to exit, and therefore will be causing some objects | |
523 | * to be deallocated. To handle this, we gain a fake reference | |
524 | * to all objects we release paging areas for. This will prevent | |
525 | * a duplicate deallocation. This routine is probably full of | |
526 | * race conditions! | |
527 | */ | |
528 | ||
529 | void vm_object_shutdown() | |
530 | { | |
531 | register vm_object_t object; | |
532 | ||
533 | /* | |
534 | * Clean up the object cache *before* we screw up the reference | |
535 | * counts on all of the objects. | |
536 | */ | |
537 | ||
538 | vm_object_cache_clear(); | |
539 | ||
540 | printf("free paging spaces: "); | |
541 | ||
542 | /* | |
543 | * First we gain a reference to each object so that | |
544 | * no one else will deallocate them. | |
545 | */ | |
546 | ||
547 | simple_lock(&vm_object_list_lock); | |
548 | object = (vm_object_t) queue_first(&vm_object_list); | |
549 | while (!queue_end(&vm_object_list, (queue_entry_t) object)) { | |
550 | vm_object_reference(object); | |
551 | object = (vm_object_t) queue_next(&object->object_list); | |
552 | } | |
553 | simple_unlock(&vm_object_list_lock); | |
554 | ||
555 | /* | |
556 | * Now we deallocate all the paging areas. We don't need | |
557 | * to lock anything because we've reduced to a single | |
558 | * processor while shutting down. This also assumes that | |
559 | * no new objects are being created. | |
560 | */ | |
561 | ||
562 | object = (vm_object_t) queue_first(&vm_object_list); | |
563 | while (!queue_end(&vm_object_list, (queue_entry_t) object)) { | |
564 | if (object->pager != NULL) | |
565 | vm_pager_deallocate(object->pager); | |
566 | object = (vm_object_t) queue_next(&object->object_list); | |
567 | printf("."); | |
568 | } | |
569 | printf("done.\n"); | |
570 | } | |
571 | ||
572 | /* | |
573 | * vm_object_pmap_copy: | |
574 | * | |
575 | * Makes all physical pages in the specified | |
576 | * object range copy-on-write. No writeable | |
577 | * references to these pages should remain. | |
578 | * | |
579 | * The object must *not* be locked. | |
580 | */ | |
581 | void vm_object_pmap_copy(object, start, end) | |
582 | register vm_object_t object; | |
583 | register vm_offset_t start; | |
584 | register vm_offset_t end; | |
585 | { | |
586 | register vm_page_t p; | |
587 | ||
588 | if (object == NULL) | |
589 | return; | |
590 | ||
591 | vm_object_lock(object); | |
592 | p = (vm_page_t) queue_first(&object->memq); | |
593 | while (!queue_end(&object->memq, (queue_entry_t) p)) { | |
594 | if ((start <= p->offset) && (p->offset < end)) { | |
595 | pmap_page_protect(VM_PAGE_TO_PHYS(p), VM_PROT_READ); | |
596 | p->copy_on_write = TRUE; | |
597 | } | |
598 | p = (vm_page_t) queue_next(&p->listq); | |
599 | } | |
600 | vm_object_unlock(object); | |
601 | } | |
602 | ||
603 | /* | |
604 | * vm_object_pmap_remove: | |
605 | * | |
606 | * Removes all physical pages in the specified | |
607 | * object range from all physical maps. | |
608 | * | |
609 | * The object must *not* be locked. | |
610 | */ | |
611 | void vm_object_pmap_remove(object, start, end) | |
612 | register vm_object_t object; | |
613 | register vm_offset_t start; | |
614 | register vm_offset_t end; | |
615 | { | |
616 | register vm_page_t p; | |
617 | ||
618 | if (object == NULL) | |
619 | return; | |
620 | ||
621 | vm_object_lock(object); | |
622 | p = (vm_page_t) queue_first(&object->memq); | |
623 | while (!queue_end(&object->memq, (queue_entry_t) p)) { | |
624 | if ((start <= p->offset) && (p->offset < end)) | |
625 | pmap_page_protect(VM_PAGE_TO_PHYS(p), VM_PROT_NONE); | |
626 | p = (vm_page_t) queue_next(&p->listq); | |
627 | } | |
628 | vm_object_unlock(object); | |
629 | } | |
630 | ||
631 | /* | |
632 | * vm_object_copy: | |
633 | * | |
634 | * Create a new object which is a copy of an existing | |
635 | * object, and mark all of the pages in the existing | |
636 | * object 'copy-on-write'. The new object has one reference. | |
637 | * Returns the new object. | |
638 | * | |
639 | * May defer the copy until later if the object is not backed | |
640 | * up by a non-default pager. | |
641 | */ | |
642 | void vm_object_copy(src_object, src_offset, size, | |
643 | dst_object, dst_offset, src_needs_copy) | |
644 | register vm_object_t src_object; | |
645 | vm_offset_t src_offset; | |
646 | vm_size_t size; | |
647 | vm_object_t *dst_object; /* OUT */ | |
648 | vm_offset_t *dst_offset; /* OUT */ | |
649 | boolean_t *src_needs_copy; /* OUT */ | |
650 | { | |
651 | register vm_object_t new_copy; | |
652 | register vm_object_t old_copy; | |
653 | vm_offset_t new_start, new_end; | |
654 | ||
655 | register vm_page_t p; | |
656 | ||
657 | if (src_object == NULL) { | |
658 | /* | |
659 | * Nothing to copy | |
660 | */ | |
661 | *dst_object = NULL; | |
662 | *dst_offset = 0; | |
663 | *src_needs_copy = FALSE; | |
664 | return; | |
665 | } | |
666 | ||
667 | /* | |
668 | * If the object's pager is null_pager or the | |
669 | * default pager, we don't have to make a copy | |
670 | * of it. Instead, we set the needs copy flag and | |
671 | * make a shadow later. | |
672 | */ | |
673 | ||
674 | vm_object_lock(src_object); | |
675 | if (src_object->pager == NULL || | |
676 | src_object->internal) { | |
677 | ||
678 | /* | |
679 | * Make another reference to the object | |
680 | */ | |
681 | src_object->ref_count++; | |
682 | ||
683 | /* | |
684 | * Mark all of the pages copy-on-write. | |
685 | */ | |
686 | for (p = (vm_page_t) queue_first(&src_object->memq); | |
687 | !queue_end(&src_object->memq, (queue_entry_t)p); | |
688 | p = (vm_page_t) queue_next(&p->listq)) { | |
689 | if (src_offset <= p->offset && | |
690 | p->offset < src_offset + size) | |
691 | p->copy_on_write = TRUE; | |
692 | } | |
693 | vm_object_unlock(src_object); | |
694 | ||
695 | *dst_object = src_object; | |
696 | *dst_offset = src_offset; | |
697 | ||
698 | /* | |
699 | * Must make a shadow when write is desired | |
700 | */ | |
701 | *src_needs_copy = TRUE; | |
702 | return; | |
703 | } | |
704 | ||
705 | /* | |
706 | * Try to collapse the object before copying it. | |
707 | */ | |
708 | vm_object_collapse(src_object); | |
709 | ||
710 | /* | |
711 | * If the object has a pager, the pager wants to | |
712 | * see all of the changes. We need a copy-object | |
713 | * for the changed pages. | |
714 | * | |
715 | * If there is a copy-object, and it is empty, | |
716 | * no changes have been made to the object since the | |
717 | * copy-object was made. We can use the same copy- | |
718 | * object. | |
719 | */ | |
720 | ||
721 | Retry1: | |
722 | old_copy = src_object->copy; | |
723 | if (old_copy != NULL) { | |
724 | /* | |
725 | * Try to get the locks (out of order) | |
726 | */ | |
727 | if (!vm_object_lock_try(old_copy)) { | |
728 | vm_object_unlock(src_object); | |
729 | ||
730 | /* should spin a bit here... */ | |
731 | vm_object_lock(src_object); | |
732 | goto Retry1; | |
733 | } | |
734 | ||
735 | if (old_copy->resident_page_count == 0 && | |
736 | old_copy->pager == NULL) { | |
737 | /* | |
738 | * Return another reference to | |
739 | * the existing copy-object. | |
740 | */ | |
741 | old_copy->ref_count++; | |
742 | vm_object_unlock(old_copy); | |
743 | vm_object_unlock(src_object); | |
744 | *dst_object = old_copy; | |
745 | *dst_offset = src_offset; | |
746 | *src_needs_copy = FALSE; | |
747 | return; | |
748 | } | |
749 | vm_object_unlock(old_copy); | |
750 | } | |
751 | vm_object_unlock(src_object); | |
752 | ||
753 | /* | |
754 | * If the object has a pager, the pager wants | |
755 | * to see all of the changes. We must make | |
756 | * a copy-object and put the changed pages there. | |
757 | * | |
758 | * The copy-object is always made large enough to | |
759 | * completely shadow the original object, since | |
760 | * it may have several users who want to shadow | |
761 | * the original object at different points. | |
762 | */ | |
763 | ||
764 | new_copy = vm_object_allocate(src_object->size); | |
765 | ||
766 | Retry2: | |
767 | vm_object_lock(src_object); | |
768 | /* | |
769 | * Copy object may have changed while we were unlocked | |
770 | */ | |
771 | old_copy = src_object->copy; | |
772 | if (old_copy != NULL) { | |
773 | /* | |
774 | * Try to get the locks (out of order) | |
775 | */ | |
776 | if (!vm_object_lock_try(old_copy)) { | |
777 | vm_object_unlock(src_object); | |
778 | goto Retry2; | |
779 | } | |
780 | ||
781 | /* | |
782 | * Consistency check | |
783 | */ | |
784 | if (old_copy->shadow != src_object || | |
785 | old_copy->shadow_offset != (vm_offset_t) 0) | |
786 | panic("vm_object_copy: copy/shadow inconsistency"); | |
787 | ||
788 | /* | |
789 | * Make the old copy-object shadow the new one. | |
790 | * It will receive no more pages from the original | |
791 | * object. | |
792 | */ | |
793 | ||
794 | src_object->ref_count--; /* remove ref. from old_copy */ | |
795 | old_copy->shadow = new_copy; | |
796 | new_copy->ref_count++; /* locking not needed - we | |
797 | have the only pointer */ | |
798 | vm_object_unlock(old_copy); /* done with old_copy */ | |
799 | } | |
800 | ||
801 | new_start = (vm_offset_t) 0; /* always shadow original at 0 */ | |
802 | new_end = (vm_offset_t) new_copy->size; /* for the whole object */ | |
803 | ||
804 | /* | |
805 | * Point the new copy at the existing object. | |
806 | */ | |
807 | ||
808 | new_copy->shadow = src_object; | |
809 | new_copy->shadow_offset = new_start; | |
810 | src_object->ref_count++; | |
811 | src_object->copy = new_copy; | |
812 | ||
813 | /* | |
814 | * Mark all the affected pages of the existing object | |
815 | * copy-on-write. | |
816 | */ | |
817 | p = (vm_page_t) queue_first(&src_object->memq); | |
818 | while (!queue_end(&src_object->memq, (queue_entry_t) p)) { | |
819 | if ((new_start <= p->offset) && (p->offset < new_end)) | |
820 | p->copy_on_write = TRUE; | |
821 | p = (vm_page_t) queue_next(&p->listq); | |
822 | } | |
823 | ||
824 | vm_object_unlock(src_object); | |
825 | ||
826 | *dst_object = new_copy; | |
827 | *dst_offset = src_offset - new_start; | |
828 | *src_needs_copy = FALSE; | |
829 | } | |
830 | ||
831 | /* | |
832 | * vm_object_shadow: | |
833 | * | |
834 | * Create a new object which is backed by the | |
835 | * specified existing object range. The source | |
836 | * object reference is deallocated. | |
837 | * | |
838 | * The new object and offset into that object | |
839 | * are returned in the source parameters. | |
840 | */ | |
841 | ||
842 | void vm_object_shadow(object, offset, length) | |
843 | vm_object_t *object; /* IN/OUT */ | |
844 | vm_offset_t *offset; /* IN/OUT */ | |
845 | vm_size_t length; | |
846 | { | |
847 | register vm_object_t source; | |
848 | register vm_object_t result; | |
849 | ||
850 | source = *object; | |
851 | ||
852 | /* | |
853 | * Allocate a new object with the given length | |
854 | */ | |
855 | ||
856 | if ((result = vm_object_allocate(length)) == NULL) | |
857 | panic("vm_object_shadow: no object for shadowing"); | |
858 | ||
859 | /* | |
860 | * The new object shadows the source object, adding | |
861 | * a reference to it. Our caller changes his reference | |
862 | * to point to the new object, removing a reference to | |
863 | * the source object. Net result: no change of reference | |
864 | * count. | |
865 | */ | |
866 | result->shadow = source; | |
867 | ||
868 | /* | |
869 | * Store the offset into the source object, | |
870 | * and fix up the offset into the new object. | |
871 | */ | |
872 | ||
873 | result->shadow_offset = *offset; | |
874 | ||
875 | /* | |
876 | * Return the new things | |
877 | */ | |
878 | ||
879 | *offset = 0; | |
880 | *object = result; | |
881 | } | |
882 | ||
883 | /* | |
884 | * Set the specified object's pager to the specified pager. | |
885 | */ | |
886 | ||
887 | void vm_object_setpager(object, pager, paging_offset, | |
888 | read_only) | |
889 | vm_object_t object; | |
890 | vm_pager_t pager; | |
891 | vm_offset_t paging_offset; | |
892 | boolean_t read_only; | |
893 | { | |
894 | #ifdef lint | |
895 | read_only++; /* No longer used */ | |
896 | #endif lint | |
897 | ||
898 | vm_object_lock(object); /* XXX ? */ | |
899 | object->pager = pager; | |
900 | object->paging_offset = paging_offset; | |
901 | vm_object_unlock(object); /* XXX ? */ | |
902 | } | |
903 | ||
904 | /* | |
905 | * vm_object_hash hashes the pager/id pair. | |
906 | */ | |
907 | ||
908 | #define vm_object_hash(pager) \ | |
909 | (((unsigned)pager)%VM_OBJECT_HASH_COUNT) | |
910 | ||
911 | /* | |
912 | * vm_object_lookup looks in the object cache for an object with the | |
913 | * specified pager and paging id. | |
914 | */ | |
915 | ||
916 | vm_object_t vm_object_lookup(pager) | |
917 | vm_pager_t pager; | |
918 | { | |
919 | register queue_t bucket; | |
920 | register vm_object_hash_entry_t entry; | |
921 | vm_object_t object; | |
922 | ||
923 | bucket = &vm_object_hashtable[vm_object_hash(pager)]; | |
924 | ||
925 | vm_object_cache_lock(); | |
926 | ||
927 | entry = (vm_object_hash_entry_t) queue_first(bucket); | |
928 | while (!queue_end(bucket, (queue_entry_t) entry)) { | |
929 | object = entry->object; | |
930 | if (object->pager == pager) { | |
931 | vm_object_lock(object); | |
932 | if (object->ref_count == 0) { | |
933 | queue_remove(&vm_object_cached_list, object, | |
934 | vm_object_t, cached_list); | |
935 | vm_object_cached--; | |
936 | } | |
937 | object->ref_count++; | |
938 | vm_object_unlock(object); | |
939 | vm_object_cache_unlock(); | |
940 | return(object); | |
941 | } | |
942 | entry = (vm_object_hash_entry_t) queue_next(&entry->hash_links); | |
943 | } | |
944 | ||
945 | vm_object_cache_unlock(); | |
946 | return(NULL); | |
947 | } | |
948 | ||
949 | /* | |
950 | * vm_object_enter enters the specified object/pager/id into | |
951 | * the hash table. | |
952 | */ | |
953 | ||
954 | void vm_object_enter(object, pager) | |
955 | vm_object_t object; | |
956 | vm_pager_t pager; | |
957 | { | |
958 | register queue_t bucket; | |
959 | register vm_object_hash_entry_t entry; | |
960 | ||
961 | /* | |
962 | * We don't cache null objects, and we can't cache | |
963 | * objects with the null pager. | |
964 | */ | |
965 | ||
966 | if (object == NULL) | |
967 | return; | |
968 | if (pager == NULL) | |
969 | return; | |
970 | ||
971 | bucket = &vm_object_hashtable[vm_object_hash(pager)]; | |
972 | entry = (vm_object_hash_entry_t) | |
973 | malloc((u_long)sizeof *entry, M_VMOBJHASH, M_WAITOK); | |
974 | entry->object = object; | |
975 | object->can_persist = TRUE; | |
976 | ||
977 | vm_object_cache_lock(); | |
978 | queue_enter(bucket, entry, vm_object_hash_entry_t, hash_links); | |
979 | vm_object_cache_unlock(); | |
980 | } | |
981 | ||
982 | /* | |
983 | * vm_object_remove: | |
984 | * | |
985 | * Remove the pager from the hash table. | |
986 | * Note: This assumes that the object cache | |
987 | * is locked. XXX this should be fixed | |
988 | * by reorganizing vm_object_deallocate. | |
989 | */ | |
990 | vm_object_remove(pager) | |
991 | register vm_pager_t pager; | |
992 | { | |
993 | register queue_t bucket; | |
994 | register vm_object_hash_entry_t entry; | |
995 | register vm_object_t object; | |
996 | ||
997 | bucket = &vm_object_hashtable[vm_object_hash(pager)]; | |
998 | ||
999 | entry = (vm_object_hash_entry_t) queue_first(bucket); | |
1000 | while (!queue_end(bucket, (queue_entry_t) entry)) { | |
1001 | object = entry->object; | |
1002 | if (object->pager == pager) { | |
1003 | queue_remove(bucket, entry, vm_object_hash_entry_t, | |
1004 | hash_links); | |
1005 | free((caddr_t)entry, M_VMOBJHASH); | |
1006 | break; | |
1007 | } | |
1008 | entry = (vm_object_hash_entry_t) queue_next(&entry->hash_links); | |
1009 | } | |
1010 | } | |
1011 | ||
1012 | /* | |
1013 | * vm_object_cache_clear removes all objects from the cache. | |
1014 | * | |
1015 | */ | |
1016 | ||
1017 | void vm_object_cache_clear() | |
1018 | { | |
1019 | register vm_object_t object; | |
1020 | ||
1021 | /* | |
1022 | * Remove each object in the cache by scanning down the | |
1023 | * list of cached objects. | |
1024 | */ | |
1025 | vm_object_cache_lock(); | |
1026 | while (!queue_empty(&vm_object_cached_list)) { | |
1027 | object = (vm_object_t) queue_first(&vm_object_cached_list); | |
1028 | vm_object_cache_unlock(); | |
1029 | ||
1030 | /* | |
1031 | * Note: it is important that we use vm_object_lookup | |
1032 | * to gain a reference, and not vm_object_reference, because | |
1033 | * the logic for removing an object from the cache lies in | |
1034 | * lookup. | |
1035 | */ | |
1036 | if (object != vm_object_lookup(object->pager)) | |
1037 | panic("vm_object_cache_clear: I'm sooo confused."); | |
1038 | pager_cache(object, FALSE); | |
1039 | ||
1040 | vm_object_cache_lock(); | |
1041 | } | |
1042 | vm_object_cache_unlock(); | |
1043 | } | |
1044 | ||
1045 | boolean_t vm_object_collapse_allowed = TRUE; | |
1046 | /* | |
1047 | * vm_object_collapse: | |
1048 | * | |
1049 | * Collapse an object with the object backing it. | |
1050 | * Pages in the backing object are moved into the | |
1051 | * parent, and the backing object is deallocated. | |
1052 | * | |
1053 | * Requires that the object be locked and the page | |
1054 | * queues be unlocked. | |
1055 | * | |
1056 | */ | |
1057 | void vm_object_collapse(object) | |
1058 | register vm_object_t object; | |
1059 | ||
1060 | { | |
1061 | register vm_object_t backing_object; | |
1062 | register vm_offset_t backing_offset; | |
1063 | register vm_size_t size; | |
1064 | register vm_offset_t new_offset; | |
1065 | register vm_page_t p, pp; | |
1066 | ||
1067 | if (!vm_object_collapse_allowed) | |
1068 | return; | |
1069 | ||
1070 | while (TRUE) { | |
1071 | /* | |
1072 | * Verify that the conditions are right for collapse: | |
1073 | * | |
1074 | * The object exists and no pages in it are currently | |
1075 | * being paged out (or have ever been paged out). | |
1076 | */ | |
1077 | if (object == NULL || | |
1078 | object->paging_in_progress != 0 || | |
1079 | object->pager != NULL) | |
1080 | return; | |
1081 | ||
1082 | /* | |
1083 | * There is a backing object, and | |
1084 | */ | |
1085 | ||
1086 | if ((backing_object = object->shadow) == NULL) | |
1087 | return; | |
1088 | ||
1089 | vm_object_lock(backing_object); | |
1090 | /* | |
1091 | * ... | |
1092 | * The backing object is not read_only, | |
1093 | * and no pages in the backing object are | |
1094 | * currently being paged out. | |
1095 | * The backing object is internal. | |
1096 | */ | |
1097 | ||
1098 | if (!backing_object->internal || | |
1099 | backing_object->paging_in_progress != 0) { | |
1100 | vm_object_unlock(backing_object); | |
1101 | return; | |
1102 | } | |
1103 | ||
1104 | /* | |
1105 | * The backing object can't be a copy-object: | |
1106 | * the shadow_offset for the copy-object must stay | |
1107 | * as 0. Furthermore (for the 'we have all the | |
1108 | * pages' case), if we bypass backing_object and | |
1109 | * just shadow the next object in the chain, old | |
1110 | * pages from that object would then have to be copied | |
1111 | * BOTH into the (former) backing_object and into the | |
1112 | * parent object. | |
1113 | */ | |
1114 | if (backing_object->shadow != NULL && | |
1115 | backing_object->shadow->copy != NULL) { | |
1116 | vm_object_unlock(backing_object); | |
1117 | return; | |
1118 | } | |
1119 | ||
1120 | /* | |
1121 | * We know that we can either collapse the backing | |
1122 | * object (if the parent is the only reference to | |
1123 | * it) or (perhaps) remove the parent's reference | |
1124 | * to it. | |
1125 | */ | |
1126 | ||
1127 | backing_offset = object->shadow_offset; | |
1128 | size = object->size; | |
1129 | ||
1130 | /* | |
1131 | * If there is exactly one reference to the backing | |
1132 | * object, we can collapse it into the parent. | |
1133 | */ | |
1134 | ||
1135 | if (backing_object->ref_count == 1) { | |
1136 | ||
1137 | /* | |
1138 | * We can collapse the backing object. | |
1139 | * | |
1140 | * Move all in-memory pages from backing_object | |
1141 | * to the parent. Pages that have been paged out | |
1142 | * will be overwritten by any of the parent's | |
1143 | * pages that shadow them. | |
1144 | */ | |
1145 | ||
1146 | while (!queue_empty(&backing_object->memq)) { | |
1147 | ||
1148 | p = (vm_page_t) | |
1149 | queue_first(&backing_object->memq); | |
1150 | ||
1151 | new_offset = (p->offset - backing_offset); | |
1152 | ||
1153 | /* | |
1154 | * If the parent has a page here, or if | |
1155 | * this page falls outside the parent, | |
1156 | * dispose of it. | |
1157 | * | |
1158 | * Otherwise, move it as planned. | |
1159 | */ | |
1160 | ||
1161 | if (p->offset < backing_offset || | |
1162 | new_offset >= size) { | |
1163 | vm_page_lock_queues(); | |
1164 | vm_page_free(p); | |
1165 | vm_page_unlock_queues(); | |
1166 | } else { | |
1167 | pp = vm_page_lookup(object, new_offset); | |
1168 | if (pp != NULL && !pp->fake) { | |
1169 | vm_page_lock_queues(); | |
1170 | vm_page_free(p); | |
1171 | vm_page_unlock_queues(); | |
1172 | } | |
1173 | else { | |
1174 | if (pp) { | |
78ed81a3 | 1175 | #if 1 |
1176 | /* | |
1177 | * This should never happen -- the | |
1178 | * parent cannot have ever had an | |
1179 | * external memory object, and thus | |
1180 | * cannot have absent pages. | |
1181 | */ | |
1182 | panic("vm_object_collapse: bad case"); | |
1183 | /* andrew@werple.apana.org.au - from | |
1184 | mach 3.0 VM */ | |
1185 | #else | |
15637ed4 RG |
1186 | /* may be someone waiting for it */ |
1187 | PAGE_WAKEUP(pp); | |
1188 | vm_page_lock_queues(); | |
1189 | vm_page_free(pp); | |
1190 | vm_page_unlock_queues(); | |
78ed81a3 | 1191 | #endif |
15637ed4 | 1192 | } |
78ed81a3 | 1193 | /* |
1194 | * Parent now has no page. | |
1195 | * Move the backing object's page | |
1196 | * up. | |
1197 | */ | |
15637ed4 RG |
1198 | vm_page_rename(p, object, new_offset); |
1199 | } | |
1200 | } | |
1201 | } | |
1202 | ||
1203 | /* | |
1204 | * Move the pager from backing_object to object. | |
1205 | * | |
1206 | * XXX We're only using part of the paging space | |
1207 | * for keeps now... we ought to discard the | |
1208 | * unused portion. | |
1209 | */ | |
1210 | ||
1211 | object->pager = backing_object->pager; | |
78ed81a3 | 1212 | #if 1 |
1213 | /* Mach 3.0 code */ | |
1214 | /* andrew@werple.apana.org.au, 12 Feb 1993 */ | |
1215 | ||
1216 | /* | |
1217 | * If there is no pager, leave paging-offset alone. | |
1218 | */ | |
1219 | if (object->pager) | |
1220 | object->paging_offset = | |
1221 | backing_object->paging_offset + | |
1222 | backing_offset; | |
1223 | #else | |
1224 | /* old VM 2.5 version */ | |
15637ed4 | 1225 | object->paging_offset += backing_offset; |
78ed81a3 | 1226 | #endif |
15637ed4 RG |
1227 | |
1228 | backing_object->pager = NULL; | |
1229 | ||
1230 | /* | |
1231 | * Object now shadows whatever backing_object did. | |
1232 | * Note that the reference to backing_object->shadow | |
1233 | * moves from within backing_object to within object. | |
1234 | */ | |
1235 | ||
1236 | object->shadow = backing_object->shadow; | |
1237 | object->shadow_offset += backing_object->shadow_offset; | |
1238 | if (object->shadow != NULL && | |
1239 | object->shadow->copy != NULL) { | |
1240 | panic("vm_object_collapse: we collapsed a copy-object!"); | |
1241 | } | |
1242 | /* | |
1243 | * Discard backing_object. | |
1244 | * | |
1245 | * Since the backing object has no pages, no | |
1246 | * pager left, and no object references within it, | |
1247 | * all that is necessary is to dispose of it. | |
1248 | */ | |
1249 | ||
1250 | vm_object_unlock(backing_object); | |
1251 | ||
1252 | simple_lock(&vm_object_list_lock); | |
1253 | queue_remove(&vm_object_list, backing_object, | |
1254 | vm_object_t, object_list); | |
1255 | vm_object_count--; | |
1256 | simple_unlock(&vm_object_list_lock); | |
1257 | ||
1258 | free((caddr_t)backing_object, M_VMOBJ); | |
1259 | ||
1260 | object_collapses++; | |
1261 | } | |
1262 | else { | |
1263 | /* | |
1264 | * If all of the pages in the backing object are | |
1265 | * shadowed by the parent object, the parent | |
1266 | * object no longer has to shadow the backing | |
1267 | * object; it can shadow the next one in the | |
1268 | * chain. | |
1269 | * | |
1270 | * The backing object must not be paged out - we'd | |
1271 | * have to check all of the paged-out pages, as | |
1272 | * well. | |
1273 | */ | |
1274 | ||
1275 | if (backing_object->pager != NULL) { | |
1276 | vm_object_unlock(backing_object); | |
1277 | return; | |
1278 | } | |
1279 | ||
1280 | /* | |
1281 | * Should have a check for a 'small' number | |
1282 | * of pages here. | |
1283 | */ | |
1284 | ||
1285 | p = (vm_page_t) queue_first(&backing_object->memq); | |
1286 | while (!queue_end(&backing_object->memq, | |
1287 | (queue_entry_t) p)) { | |
1288 | ||
1289 | new_offset = (p->offset - backing_offset); | |
1290 | ||
1291 | /* | |
1292 | * If the parent has a page here, or if | |
1293 | * this page falls outside the parent, | |
1294 | * keep going. | |
1295 | * | |
1296 | * Otherwise, the backing_object must be | |
1297 | * left in the chain. | |
1298 | */ | |
1299 | ||
1300 | if (p->offset >= backing_offset && | |
1301 | new_offset <= size && | |
1302 | ((pp = vm_page_lookup(object, new_offset)) | |
1303 | == NULL || | |
1304 | pp->fake)) { | |
1305 | /* | |
1306 | * Page still needed. | |
1307 | * Can't go any further. | |
1308 | */ | |
1309 | vm_object_unlock(backing_object); | |
1310 | return; | |
1311 | } | |
1312 | p = (vm_page_t) queue_next(&p->listq); | |
1313 | } | |
1314 | ||
1315 | /* | |
1316 | * Make the parent shadow the next object | |
1317 | * in the chain. Deallocating backing_object | |
1318 | * will not remove it, since its reference | |
1319 | * count is at least 2. | |
1320 | */ | |
1321 | ||
1322 | vm_object_reference(object->shadow = backing_object->shadow); | |
1323 | object->shadow_offset += backing_object->shadow_offset; | |
1324 | ||
78ed81a3 | 1325 | #if 1 |
1326 | /* Mach 3.0 code */ | |
1327 | /* andrew@werple.apana.org.au, 12 Feb 1993 */ | |
1328 | ||
1329 | /* | |
1330 | * Backing object might have had a copy pointer | |
1331 | * to us. If it did, clear it. | |
1332 | */ | |
1333 | if (backing_object->copy == object) | |
1334 | backing_object->copy = NULL; | |
1335 | #endif | |
1336 | ||
15637ed4 RG |
1337 | /* Drop the reference count on backing_object. |
1338 | * Since its ref_count was at least 2, it | |
1339 | * will not vanish; so we don't need to call | |
1340 | * vm_object_deallocate. | |
1341 | */ | |
1342 | backing_object->ref_count--; | |
1343 | vm_object_unlock(backing_object); | |
1344 | ||
1345 | object_bypasses ++; | |
1346 | ||
1347 | } | |
1348 | ||
1349 | /* | |
1350 | * Try again with this object's new backing object. | |
1351 | */ | |
1352 | } | |
1353 | } | |
1354 | ||
1355 | /* | |
1356 | * vm_object_page_remove: [internal] | |
1357 | * | |
1358 | * Removes all physical pages in the specified | |
1359 | * object range from the object's list of pages. | |
1360 | * | |
1361 | * The object must be locked. | |
1362 | */ | |
1363 | void vm_object_page_remove(object, start, end) | |
1364 | register vm_object_t object; | |
1365 | register vm_offset_t start; | |
1366 | register vm_offset_t end; | |
1367 | { | |
1368 | register vm_page_t p, next; | |
1369 | ||
1370 | if (object == NULL) | |
1371 | return; | |
1372 | ||
1373 | p = (vm_page_t) queue_first(&object->memq); | |
1374 | while (!queue_end(&object->memq, (queue_entry_t) p)) { | |
1375 | next = (vm_page_t) queue_next(&p->listq); | |
1376 | if ((start <= p->offset) && (p->offset < end)) { | |
1377 | pmap_page_protect(VM_PAGE_TO_PHYS(p), VM_PROT_NONE); | |
1378 | vm_page_lock_queues(); | |
1379 | vm_page_free(p); | |
1380 | vm_page_unlock_queues(); | |
1381 | } | |
1382 | p = next; | |
1383 | } | |
1384 | } | |
1385 | ||
1386 | /* | |
1387 | * Routine: vm_object_coalesce | |
1388 | * Function: Coalesces two objects backing up adjoining | |
1389 | * regions of memory into a single object. | |
1390 | * | |
1391 | * returns TRUE if objects were combined. | |
1392 | * | |
1393 | * NOTE: Only works at the moment if the second object is NULL - | |
1394 | * if it's not, which object do we lock first? | |
1395 | * | |
1396 | * Parameters: | |
1397 | * prev_object First object to coalesce | |
1398 | * prev_offset Offset into prev_object | |
1399 | * next_object Second object into coalesce | |
1400 | * next_offset Offset into next_object | |
1401 | * | |
1402 | * prev_size Size of reference to prev_object | |
1403 | * next_size Size of reference to next_object | |
1404 | * | |
1405 | * Conditions: | |
1406 | * The object must *not* be locked. | |
1407 | */ | |
1408 | boolean_t vm_object_coalesce(prev_object, next_object, | |
1409 | prev_offset, next_offset, | |
1410 | prev_size, next_size) | |
1411 | ||
1412 | register vm_object_t prev_object; | |
1413 | vm_object_t next_object; | |
1414 | vm_offset_t prev_offset, next_offset; | |
1415 | vm_size_t prev_size, next_size; | |
1416 | { | |
1417 | vm_size_t newsize; | |
1418 | ||
1419 | #ifdef lint | |
1420 | next_offset++; | |
1421 | #endif lint | |
1422 | ||
1423 | if (next_object != NULL) { | |
1424 | return(FALSE); | |
1425 | } | |
1426 | ||
1427 | if (prev_object == NULL) { | |
1428 | return(TRUE); | |
1429 | } | |
1430 | ||
1431 | vm_object_lock(prev_object); | |
1432 | ||
1433 | /* | |
1434 | * Try to collapse the object first | |
1435 | */ | |
1436 | vm_object_collapse(prev_object); | |
1437 | ||
1438 | /* | |
1439 | * Can't coalesce if: | |
1440 | * . more than one reference | |
1441 | * . paged out | |
1442 | * . shadows another object | |
1443 | * . has a copy elsewhere | |
1444 | * (any of which mean that the pages not mapped to | |
1445 | * prev_entry may be in use anyway) | |
1446 | */ | |
1447 | ||
1448 | if (prev_object->ref_count > 1 || | |
1449 | prev_object->pager != NULL || | |
1450 | prev_object->shadow != NULL || | |
1451 | prev_object->copy != NULL) { | |
1452 | vm_object_unlock(prev_object); | |
1453 | return(FALSE); | |
1454 | } | |
1455 | ||
1456 | /* | |
1457 | * Remove any pages that may still be in the object from | |
1458 | * a previous deallocation. | |
1459 | */ | |
1460 | ||
1461 | vm_object_page_remove(prev_object, | |
1462 | prev_offset + prev_size, | |
1463 | prev_offset + prev_size + next_size); | |
1464 | ||
1465 | /* | |
1466 | * Extend the object if necessary. | |
1467 | */ | |
1468 | newsize = prev_offset + prev_size + next_size; | |
1469 | if (newsize > prev_object->size) | |
1470 | prev_object->size = newsize; | |
1471 | ||
1472 | vm_object_unlock(prev_object); | |
1473 | return(TRUE); | |
1474 | } | |
1475 | ||
78ed81a3 | 1476 | #if defined(DEBUG) || (NDDB > 0) |
15637ed4 RG |
1477 | /* |
1478 | * vm_object_print: [ debug ] | |
1479 | */ | |
1480 | void vm_object_print(object, full) | |
1481 | vm_object_t object; | |
1482 | boolean_t full; | |
1483 | { | |
1484 | register vm_page_t p; | |
1485 | extern indent; | |
1486 | ||
1487 | register int count; | |
1488 | ||
1489 | if (object == NULL) | |
1490 | return; | |
1491 | ||
1492 | iprintf("Object 0x%x: size=0x%x, res=%d, ref=%d, ", | |
1493 | (int) object, (int) object->size, | |
1494 | object->resident_page_count, object->ref_count); | |
1495 | printf("pager=0x%x+0x%x, shadow=(0x%x)+0x%x\n", | |
1496 | (int) object->pager, (int) object->paging_offset, | |
1497 | (int) object->shadow, (int) object->shadow_offset); | |
1498 | printf("cache: next=0x%x, prev=0x%x\n", | |
1499 | object->cached_list.next, object->cached_list.prev); | |
1500 | ||
1501 | if (!full) | |
1502 | return; | |
1503 | ||
1504 | indent += 2; | |
1505 | count = 0; | |
1506 | p = (vm_page_t) queue_first(&object->memq); | |
1507 | while (!queue_end(&object->memq, (queue_entry_t) p)) { | |
1508 | if (count == 0) | |
1509 | iprintf("memory:="); | |
1510 | else if (count == 6) { | |
1511 | printf("\n"); | |
1512 | iprintf(" ..."); | |
1513 | count = 0; | |
1514 | } else | |
1515 | printf(","); | |
1516 | count++; | |
1517 | ||
1518 | printf("(off=0x%x,page=0x%x)", p->offset, VM_PAGE_TO_PHYS(p)); | |
1519 | p = (vm_page_t) queue_next(&p->listq); | |
1520 | } | |
1521 | if (count != 0) | |
1522 | printf("\n"); | |
1523 | indent -= 2; | |
1524 | } | |
78ed81a3 | 1525 | #endif /* defined(DEBUG) || (NDDB > 0) */ |