FreeBSD/Linux Kernel Cross Reference
sys/uvm/uvm_aobj.c
1 /* $NetBSD: uvm_aobj.c,v 1.64 2004/04/25 16:42:44 simonb Exp $ */
2
3 /*
4 * Copyright (c) 1998 Chuck Silvers, Charles D. Cranor and
5 * Washington University.
6 * All rights reserved.
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 Charles D. Cranor and
19 * Washington University.
20 * 4. The name of the author may not be used to endorse or promote products
21 * derived from this software without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
33 *
34 * from: Id: uvm_aobj.c,v 1.1.2.5 1998/02/06 05:14:38 chs Exp
35 */
36 /*
37 * uvm_aobj.c: anonymous memory uvm_object pager
38 *
39 * author: Chuck Silvers <chuq@chuq.com>
40 * started: Jan-1998
41 *
42 * - design mostly from Chuck Cranor
43 */
44
45 #include <sys/cdefs.h>
46 __KERNEL_RCSID(0, "$NetBSD: uvm_aobj.c,v 1.64 2004/04/25 16:42:44 simonb Exp $");
47
48 #include "opt_uvmhist.h"
49
50 #include <sys/param.h>
51 #include <sys/systm.h>
52 #include <sys/proc.h>
53 #include <sys/malloc.h>
54 #include <sys/kernel.h>
55 #include <sys/pool.h>
56 #include <sys/kernel.h>
57
58 #include <uvm/uvm.h>
59
60 /*
61 * an aobj manages anonymous-memory backed uvm_objects. in addition
62 * to keeping the list of resident pages, it also keeps a list of
63 * allocated swap blocks. depending on the size of the aobj this list
64 * of allocated swap blocks is either stored in an array (small objects)
65 * or in a hash table (large objects).
66 */
67
68 /*
69 * local structures
70 */
71
72 /*
73 * for hash tables, we break the address space of the aobj into blocks
74 * of UAO_SWHASH_CLUSTER_SIZE pages. we require the cluster size to
75 * be a power of two.
76 */
77
78 #define UAO_SWHASH_CLUSTER_SHIFT 4
79 #define UAO_SWHASH_CLUSTER_SIZE (1 << UAO_SWHASH_CLUSTER_SHIFT)
80
81 /* get the "tag" for this page index */
82 #define UAO_SWHASH_ELT_TAG(PAGEIDX) \
83 ((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT)
84
85 /* given an ELT and a page index, find the swap slot */
86 #define UAO_SWHASH_ELT_PAGESLOT(ELT, PAGEIDX) \
87 ((ELT)->slots[(PAGEIDX) & (UAO_SWHASH_CLUSTER_SIZE - 1)])
88
89 /* given an ELT, return its pageidx base */
90 #define UAO_SWHASH_ELT_PAGEIDX_BASE(ELT) \
91 ((ELT)->tag << UAO_SWHASH_CLUSTER_SHIFT)
92
93 /*
94 * the swhash hash function
95 */
96
97 #define UAO_SWHASH_HASH(AOBJ, PAGEIDX) \
98 (&(AOBJ)->u_swhash[(((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT) \
99 & (AOBJ)->u_swhashmask)])
100
101 /*
102 * the swhash threshhold determines if we will use an array or a
103 * hash table to store the list of allocated swap blocks.
104 */
105
106 #define UAO_SWHASH_THRESHOLD (UAO_SWHASH_CLUSTER_SIZE * 4)
107 #define UAO_USES_SWHASH(AOBJ) \
108 ((AOBJ)->u_pages > UAO_SWHASH_THRESHOLD) /* use hash? */
109
110 /*
111 * the number of buckets in a swhash, with an upper bound
112 */
113
114 #define UAO_SWHASH_MAXBUCKETS 256
115 #define UAO_SWHASH_BUCKETS(AOBJ) \
116 (MIN((AOBJ)->u_pages >> UAO_SWHASH_CLUSTER_SHIFT, \
117 UAO_SWHASH_MAXBUCKETS))
118
119
120 /*
121 * uao_swhash_elt: when a hash table is being used, this structure defines
122 * the format of an entry in the bucket list.
123 */
124
125 struct uao_swhash_elt {
126 LIST_ENTRY(uao_swhash_elt) list; /* the hash list */
127 voff_t tag; /* our 'tag' */
128 int count; /* our number of active slots */
129 int slots[UAO_SWHASH_CLUSTER_SIZE]; /* the slots */
130 };
131
132 /*
133 * uao_swhash: the swap hash table structure
134 */
135
136 LIST_HEAD(uao_swhash, uao_swhash_elt);
137
138 /*
139 * uao_swhash_elt_pool: pool of uao_swhash_elt structures
140 * NOTE: Pages for this pool must not come from a pageable kernel map!
141 */
142 POOL_INIT(uao_swhash_elt_pool, sizeof(struct uao_swhash_elt), 0, 0, 0,
143 "uaoeltpl", NULL);
144
145 /*
146 * uvm_aobj: the actual anon-backed uvm_object
147 *
148 * => the uvm_object is at the top of the structure, this allows
149 * (struct uvm_aobj *) == (struct uvm_object *)
150 * => only one of u_swslots and u_swhash is used in any given aobj
151 */
152
153 struct uvm_aobj {
154 struct uvm_object u_obj; /* has: lock, pgops, memq, #pages, #refs */
155 int u_pages; /* number of pages in entire object */
156 int u_flags; /* the flags (see uvm_aobj.h) */
157 int *u_swslots; /* array of offset->swapslot mappings */
158 /*
159 * hashtable of offset->swapslot mappings
160 * (u_swhash is an array of bucket heads)
161 */
162 struct uao_swhash *u_swhash;
163 u_long u_swhashmask; /* mask for hashtable */
164 LIST_ENTRY(uvm_aobj) u_list; /* global list of aobjs */
165 };
166
167 /*
168 * uvm_aobj_pool: pool of uvm_aobj structures
169 */
170 POOL_INIT(uvm_aobj_pool, sizeof(struct uvm_aobj), 0, 0, 0, "aobjpl",
171 &pool_allocator_nointr);
172
173 MALLOC_DEFINE(M_UVMAOBJ, "UVM aobj", "UVM aobj and related structures");
174
175 /*
176 * local functions
177 */
178
179 static struct uao_swhash_elt *uao_find_swhash_elt
180 (struct uvm_aobj *, int, boolean_t);
181
182 static void uao_free(struct uvm_aobj *);
183 static int uao_get(struct uvm_object *, voff_t, struct vm_page **,
184 int *, int, vm_prot_t, int, int);
185 static boolean_t uao_put(struct uvm_object *, voff_t, voff_t, int);
186 static boolean_t uao_pagein(struct uvm_aobj *, int, int);
187 static boolean_t uao_pagein_page(struct uvm_aobj *, int);
188
189 /*
190 * aobj_pager
191 *
192 * note that some functions (e.g. put) are handled elsewhere
193 */
194
195 struct uvm_pagerops aobj_pager = {
196 NULL, /* init */
197 uao_reference, /* reference */
198 uao_detach, /* detach */
199 NULL, /* fault */
200 uao_get, /* get */
201 uao_put, /* flush */
202 };
203
204 /*
205 * uao_list: global list of active aobjs, locked by uao_list_lock
206 */
207
208 static LIST_HEAD(aobjlist, uvm_aobj) uao_list;
209 static struct simplelock uao_list_lock;
210
211 /*
212 * functions
213 */
214
215 /*
216 * hash table/array related functions
217 */
218
219 /*
220 * uao_find_swhash_elt: find (or create) a hash table entry for a page
221 * offset.
222 *
223 * => the object should be locked by the caller
224 */
225
226 static struct uao_swhash_elt *
227 uao_find_swhash_elt(aobj, pageidx, create)
228 struct uvm_aobj *aobj;
229 int pageidx;
230 boolean_t create;
231 {
232 struct uao_swhash *swhash;
233 struct uao_swhash_elt *elt;
234 voff_t page_tag;
235
236 swhash = UAO_SWHASH_HASH(aobj, pageidx);
237 page_tag = UAO_SWHASH_ELT_TAG(pageidx);
238
239 /*
240 * now search the bucket for the requested tag
241 */
242
243 LIST_FOREACH(elt, swhash, list) {
244 if (elt->tag == page_tag) {
245 return elt;
246 }
247 }
248 if (!create) {
249 return NULL;
250 }
251
252 /*
253 * allocate a new entry for the bucket and init/insert it in
254 */
255
256 elt = pool_get(&uao_swhash_elt_pool, PR_NOWAIT);
257 if (elt == NULL) {
258 return NULL;
259 }
260 LIST_INSERT_HEAD(swhash, elt, list);
261 elt->tag = page_tag;
262 elt->count = 0;
263 memset(elt->slots, 0, sizeof(elt->slots));
264 return elt;
265 }
266
267 /*
268 * uao_find_swslot: find the swap slot number for an aobj/pageidx
269 *
270 * => object must be locked by caller
271 */
272
273 int
274 uao_find_swslot(uobj, pageidx)
275 struct uvm_object *uobj;
276 int pageidx;
277 {
278 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
279 struct uao_swhash_elt *elt;
280
281 /*
282 * if noswap flag is set, then we never return a slot
283 */
284
285 if (aobj->u_flags & UAO_FLAG_NOSWAP)
286 return(0);
287
288 /*
289 * if hashing, look in hash table.
290 */
291
292 if (UAO_USES_SWHASH(aobj)) {
293 elt = uao_find_swhash_elt(aobj, pageidx, FALSE);
294 if (elt)
295 return(UAO_SWHASH_ELT_PAGESLOT(elt, pageidx));
296 else
297 return(0);
298 }
299
300 /*
301 * otherwise, look in the array
302 */
303
304 return(aobj->u_swslots[pageidx]);
305 }
306
307 /*
308 * uao_set_swslot: set the swap slot for a page in an aobj.
309 *
310 * => setting a slot to zero frees the slot
311 * => object must be locked by caller
312 * => we return the old slot number, or -1 if we failed to allocate
313 * memory to record the new slot number
314 */
315
316 int
317 uao_set_swslot(uobj, pageidx, slot)
318 struct uvm_object *uobj;
319 int pageidx, slot;
320 {
321 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
322 struct uao_swhash_elt *elt;
323 int oldslot;
324 UVMHIST_FUNC("uao_set_swslot"); UVMHIST_CALLED(pdhist);
325 UVMHIST_LOG(pdhist, "aobj %p pageidx %d slot %d",
326 aobj, pageidx, slot, 0);
327
328 /*
329 * if noswap flag is set, then we can't set a non-zero slot.
330 */
331
332 if (aobj->u_flags & UAO_FLAG_NOSWAP) {
333 if (slot == 0)
334 return(0);
335
336 printf("uao_set_swslot: uobj = %p\n", uobj);
337 panic("uao_set_swslot: NOSWAP object");
338 }
339
340 /*
341 * are we using a hash table? if so, add it in the hash.
342 */
343
344 if (UAO_USES_SWHASH(aobj)) {
345
346 /*
347 * Avoid allocating an entry just to free it again if
348 * the page had not swap slot in the first place, and
349 * we are freeing.
350 */
351
352 elt = uao_find_swhash_elt(aobj, pageidx, slot != 0);
353 if (elt == NULL) {
354 return slot ? -1 : 0;
355 }
356
357 oldslot = UAO_SWHASH_ELT_PAGESLOT(elt, pageidx);
358 UAO_SWHASH_ELT_PAGESLOT(elt, pageidx) = slot;
359
360 /*
361 * now adjust the elt's reference counter and free it if we've
362 * dropped it to zero.
363 */
364
365 if (slot) {
366 if (oldslot == 0)
367 elt->count++;
368 } else {
369 if (oldslot)
370 elt->count--;
371
372 if (elt->count == 0) {
373 LIST_REMOVE(elt, list);
374 pool_put(&uao_swhash_elt_pool, elt);
375 }
376 }
377 } else {
378 /* we are using an array */
379 oldslot = aobj->u_swslots[pageidx];
380 aobj->u_swslots[pageidx] = slot;
381 }
382 return (oldslot);
383 }
384
385 /*
386 * end of hash/array functions
387 */
388
389 /*
390 * uao_free: free all resources held by an aobj, and then free the aobj
391 *
392 * => the aobj should be dead
393 */
394
395 static void
396 uao_free(aobj)
397 struct uvm_aobj *aobj;
398 {
399 int swpgonlydelta = 0;
400
401 simple_unlock(&aobj->u_obj.vmobjlock);
402 if (UAO_USES_SWHASH(aobj)) {
403 int i, hashbuckets = aobj->u_swhashmask + 1;
404
405 /*
406 * free the swslots from each hash bucket,
407 * then the hash bucket, and finally the hash table itself.
408 */
409
410 for (i = 0; i < hashbuckets; i++) {
411 struct uao_swhash_elt *elt, *next;
412
413 for (elt = LIST_FIRST(&aobj->u_swhash[i]);
414 elt != NULL;
415 elt = next) {
416 int j;
417
418 for (j = 0; j < UAO_SWHASH_CLUSTER_SIZE; j++) {
419 int slot = elt->slots[j];
420
421 if (slot > 0) {
422 uvm_swap_free(slot, 1);
423 swpgonlydelta++;
424 }
425 }
426
427 next = LIST_NEXT(elt, list);
428 pool_put(&uao_swhash_elt_pool, elt);
429 }
430 }
431 free(aobj->u_swhash, M_UVMAOBJ);
432 } else {
433 int i;
434
435 /*
436 * free the array
437 */
438
439 for (i = 0; i < aobj->u_pages; i++) {
440 int slot = aobj->u_swslots[i];
441
442 if (slot > 0) {
443 uvm_swap_free(slot, 1);
444 swpgonlydelta++;
445 }
446 }
447 free(aobj->u_swslots, M_UVMAOBJ);
448 }
449
450 /*
451 * finally free the aobj itself
452 */
453
454 pool_put(&uvm_aobj_pool, aobj);
455
456 /*
457 * adjust the counter of pages only in swap for all
458 * the swap slots we've freed.
459 */
460
461 if (swpgonlydelta > 0) {
462 simple_lock(&uvm.swap_data_lock);
463 KASSERT(uvmexp.swpgonly >= swpgonlydelta);
464 uvmexp.swpgonly -= swpgonlydelta;
465 simple_unlock(&uvm.swap_data_lock);
466 }
467 }
468
469 /*
470 * pager functions
471 */
472
473 /*
474 * uao_create: create an aobj of the given size and return its uvm_object.
475 *
476 * => for normal use, flags are always zero
477 * => for the kernel object, the flags are:
478 * UAO_FLAG_KERNOBJ - allocate the kernel object (can only happen once)
479 * UAO_FLAG_KERNSWAP - enable swapping of kernel object (" ")
480 */
481
482 struct uvm_object *
483 uao_create(size, flags)
484 vsize_t size;
485 int flags;
486 {
487 static struct uvm_aobj kernel_object_store;
488 static int kobj_alloced = 0;
489 int pages = round_page(size) >> PAGE_SHIFT;
490 struct uvm_aobj *aobj;
491
492 /*
493 * malloc a new aobj unless we are asked for the kernel object
494 */
495
496 if (flags & UAO_FLAG_KERNOBJ) {
497 KASSERT(!kobj_alloced);
498 aobj = &kernel_object_store;
499 aobj->u_pages = pages;
500 aobj->u_flags = UAO_FLAG_NOSWAP;
501 aobj->u_obj.uo_refs = UVM_OBJ_KERN;
502 kobj_alloced = UAO_FLAG_KERNOBJ;
503 } else if (flags & UAO_FLAG_KERNSWAP) {
504 KASSERT(kobj_alloced == UAO_FLAG_KERNOBJ);
505 aobj = &kernel_object_store;
506 kobj_alloced = UAO_FLAG_KERNSWAP;
507 } else {
508 aobj = pool_get(&uvm_aobj_pool, PR_WAITOK);
509 aobj->u_pages = pages;
510 aobj->u_flags = 0;
511 aobj->u_obj.uo_refs = 1;
512 }
513
514 /*
515 * allocate hash/array if necessary
516 *
517 * note: in the KERNSWAP case no need to worry about locking since
518 * we are still booting we should be the only thread around.
519 */
520
521 if (flags == 0 || (flags & UAO_FLAG_KERNSWAP) != 0) {
522 int mflags = (flags & UAO_FLAG_KERNSWAP) != 0 ?
523 M_NOWAIT : M_WAITOK;
524
525 /* allocate hash table or array depending on object size */
526 if (UAO_USES_SWHASH(aobj)) {
527 aobj->u_swhash = hashinit(UAO_SWHASH_BUCKETS(aobj),
528 HASH_LIST, M_UVMAOBJ, mflags, &aobj->u_swhashmask);
529 if (aobj->u_swhash == NULL)
530 panic("uao_create: hashinit swhash failed");
531 } else {
532 aobj->u_swslots = malloc(pages * sizeof(int),
533 M_UVMAOBJ, mflags);
534 if (aobj->u_swslots == NULL)
535 panic("uao_create: malloc swslots failed");
536 memset(aobj->u_swslots, 0, pages * sizeof(int));
537 }
538
539 if (flags) {
540 aobj->u_flags &= ~UAO_FLAG_NOSWAP; /* clear noswap */
541 return(&aobj->u_obj);
542 }
543 }
544
545 /*
546 * init aobj fields
547 */
548
549 simple_lock_init(&aobj->u_obj.vmobjlock);
550 aobj->u_obj.pgops = &aobj_pager;
551 TAILQ_INIT(&aobj->u_obj.memq);
552 aobj->u_obj.uo_npages = 0;
553
554 /*
555 * now that aobj is ready, add it to the global list
556 */
557
558 simple_lock(&uao_list_lock);
559 LIST_INSERT_HEAD(&uao_list, aobj, u_list);
560 simple_unlock(&uao_list_lock);
561 return(&aobj->u_obj);
562 }
563
564
565
566 /*
567 * uao_init: set up aobj pager subsystem
568 *
569 * => called at boot time from uvm_pager_init()
570 */
571
572 void
573 uao_init(void)
574 {
575 static int uao_initialized;
576
577 if (uao_initialized)
578 return;
579 uao_initialized = TRUE;
580 LIST_INIT(&uao_list);
581 simple_lock_init(&uao_list_lock);
582 }
583
584 /*
585 * uao_reference: add a ref to an aobj
586 *
587 * => aobj must be unlocked
588 * => just lock it and call the locked version
589 */
590
591 void
592 uao_reference(uobj)
593 struct uvm_object *uobj;
594 {
595 simple_lock(&uobj->vmobjlock);
596 uao_reference_locked(uobj);
597 simple_unlock(&uobj->vmobjlock);
598 }
599
600 /*
601 * uao_reference_locked: add a ref to an aobj that is already locked
602 *
603 * => aobj must be locked
604 * this needs to be separate from the normal routine
605 * since sometimes we need to add a reference to an aobj when
606 * it's already locked.
607 */
608
609 void
610 uao_reference_locked(uobj)
611 struct uvm_object *uobj;
612 {
613 UVMHIST_FUNC("uao_reference"); UVMHIST_CALLED(maphist);
614
615 /*
616 * kernel_object already has plenty of references, leave it alone.
617 */
618
619 if (UVM_OBJ_IS_KERN_OBJECT(uobj))
620 return;
621
622 uobj->uo_refs++;
623 UVMHIST_LOG(maphist, "<- done (uobj=0x%x, ref = %d)",
624 uobj, uobj->uo_refs,0,0);
625 }
626
627 /*
628 * uao_detach: drop a reference to an aobj
629 *
630 * => aobj must be unlocked
631 * => just lock it and call the locked version
632 */
633
634 void
635 uao_detach(uobj)
636 struct uvm_object *uobj;
637 {
638 simple_lock(&uobj->vmobjlock);
639 uao_detach_locked(uobj);
640 }
641
642 /*
643 * uao_detach_locked: drop a reference to an aobj
644 *
645 * => aobj must be locked, and is unlocked (or freed) upon return.
646 * this needs to be separate from the normal routine
647 * since sometimes we need to detach from an aobj when
648 * it's already locked.
649 */
650
651 void
652 uao_detach_locked(uobj)
653 struct uvm_object *uobj;
654 {
655 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
656 struct vm_page *pg;
657 UVMHIST_FUNC("uao_detach"); UVMHIST_CALLED(maphist);
658
659 /*
660 * detaching from kernel_object is a noop.
661 */
662
663 if (UVM_OBJ_IS_KERN_OBJECT(uobj)) {
664 simple_unlock(&uobj->vmobjlock);
665 return;
666 }
667
668 UVMHIST_LOG(maphist," (uobj=0x%x) ref=%d", uobj,uobj->uo_refs,0,0);
669 uobj->uo_refs--;
670 if (uobj->uo_refs) {
671 simple_unlock(&uobj->vmobjlock);
672 UVMHIST_LOG(maphist, "<- done (rc>0)", 0,0,0,0);
673 return;
674 }
675
676 /*
677 * remove the aobj from the global list.
678 */
679
680 simple_lock(&uao_list_lock);
681 LIST_REMOVE(aobj, u_list);
682 simple_unlock(&uao_list_lock);
683
684 /*
685 * free all the pages left in the aobj. for each page,
686 * when the page is no longer busy (and thus after any disk i/o that
687 * it's involved in is complete), release any swap resources and
688 * free the page itself.
689 */
690
691 uvm_lock_pageq();
692 while ((pg = TAILQ_FIRST(&uobj->memq)) != NULL) {
693 pmap_page_protect(pg, VM_PROT_NONE);
694 if (pg->flags & PG_BUSY) {
695 pg->flags |= PG_WANTED;
696 uvm_unlock_pageq();
697 UVM_UNLOCK_AND_WAIT(pg, &uobj->vmobjlock, FALSE,
698 "uao_det", 0);
699 simple_lock(&uobj->vmobjlock);
700 uvm_lock_pageq();
701 continue;
702 }
703 uao_dropswap(&aobj->u_obj, pg->offset >> PAGE_SHIFT);
704 uvm_pagefree(pg);
705 }
706 uvm_unlock_pageq();
707
708 /*
709 * finally, free the aobj itself.
710 */
711
712 uao_free(aobj);
713 }
714
715 /*
716 * uao_put: flush pages out of a uvm object
717 *
718 * => object should be locked by caller. we may _unlock_ the object
719 * if (and only if) we need to clean a page (PGO_CLEANIT).
720 * XXXJRT Currently, however, we don't. In the case of cleaning
721 * XXXJRT a page, we simply just deactivate it. Should probably
722 * XXXJRT handle this better, in the future (although "flushing"
723 * XXXJRT anonymous memory isn't terribly important).
724 * => if PGO_CLEANIT is not set, then we will neither unlock the object
725 * or block.
726 * => if PGO_ALLPAGE is set, then all pages in the object are valid targets
727 * for flushing.
728 * => NOTE: we rely on the fact that the object's memq is a TAILQ and
729 * that new pages are inserted on the tail end of the list. thus,
730 * we can make a complete pass through the object in one go by starting
731 * at the head and working towards the tail (new pages are put in
732 * front of us).
733 * => NOTE: we are allowed to lock the page queues, so the caller
734 * must not be holding the lock on them [e.g. pagedaemon had
735 * better not call us with the queues locked]
736 * => we return TRUE unless we encountered some sort of I/O error
737 * XXXJRT currently never happens, as we never directly initiate
738 * XXXJRT I/O
739 *
740 * note on page traversal:
741 * we can traverse the pages in an object either by going down the
742 * linked list in "uobj->memq", or we can go over the address range
743 * by page doing hash table lookups for each address. depending
744 * on how many pages are in the object it may be cheaper to do one
745 * or the other. we set "by_list" to true if we are using memq.
746 * if the cost of a hash lookup was equal to the cost of the list
747 * traversal we could compare the number of pages in the start->stop
748 * range to the total number of pages in the object. however, it
749 * seems that a hash table lookup is more expensive than the linked
750 * list traversal, so we multiply the number of pages in the
751 * start->stop range by a penalty which we define below.
752 */
753
754 int
755 uao_put(uobj, start, stop, flags)
756 struct uvm_object *uobj;
757 voff_t start, stop;
758 int flags;
759 {
760 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
761 struct vm_page *pg, *nextpg, curmp, endmp;
762 boolean_t by_list;
763 voff_t curoff;
764 UVMHIST_FUNC("uao_put"); UVMHIST_CALLED(maphist);
765
766 curoff = 0;
767 if (flags & PGO_ALLPAGES) {
768 start = 0;
769 stop = aobj->u_pages << PAGE_SHIFT;
770 by_list = TRUE; /* always go by the list */
771 } else {
772 start = trunc_page(start);
773 stop = round_page(stop);
774 if (stop > (aobj->u_pages << PAGE_SHIFT)) {
775 printf("uao_flush: strange, got an out of range "
776 "flush (fixed)\n");
777 stop = aobj->u_pages << PAGE_SHIFT;
778 }
779 by_list = (uobj->uo_npages <=
780 ((stop - start) >> PAGE_SHIFT) * UVM_PAGE_HASH_PENALTY);
781 }
782 UVMHIST_LOG(maphist,
783 " flush start=0x%lx, stop=0x%x, by_list=%d, flags=0x%x",
784 start, stop, by_list, flags);
785
786 /*
787 * Don't need to do any work here if we're not freeing
788 * or deactivating pages.
789 */
790
791 if ((flags & (PGO_DEACTIVATE|PGO_FREE)) == 0) {
792 simple_unlock(&uobj->vmobjlock);
793 return 0;
794 }
795
796 /*
797 * Initialize the marker pages. See the comment in
798 * genfs_putpages() also.
799 */
800
801 curmp.uobject = uobj;
802 curmp.offset = (voff_t)-1;
803 curmp.flags = PG_BUSY;
804 endmp.uobject = uobj;
805 endmp.offset = (voff_t)-1;
806 endmp.flags = PG_BUSY;
807
808 /*
809 * now do it. note: we must update nextpg in the body of loop or we
810 * will get stuck. we need to use nextpg if we'll traverse the list
811 * because we may free "pg" before doing the next loop.
812 */
813
814 if (by_list) {
815 TAILQ_INSERT_TAIL(&uobj->memq, &endmp, listq);
816 nextpg = TAILQ_FIRST(&uobj->memq);
817 PHOLD(curlwp);
818 } else {
819 curoff = start;
820 nextpg = NULL; /* Quell compiler warning */
821 }
822
823 uvm_lock_pageq();
824
825 /* locked: both page queues and uobj */
826 for (;;) {
827 if (by_list) {
828 pg = nextpg;
829 if (pg == &endmp)
830 break;
831 nextpg = TAILQ_NEXT(pg, listq);
832 if (pg->offset < start || pg->offset >= stop)
833 continue;
834 } else {
835 if (curoff < stop) {
836 pg = uvm_pagelookup(uobj, curoff);
837 curoff += PAGE_SIZE;
838 } else
839 break;
840 if (pg == NULL)
841 continue;
842 }
843 switch (flags & (PGO_CLEANIT|PGO_FREE|PGO_DEACTIVATE)) {
844
845 /*
846 * XXX In these first 3 cases, we always just
847 * XXX deactivate the page. We may want to
848 * XXX handle the different cases more specifically
849 * XXX in the future.
850 */
851
852 case PGO_CLEANIT|PGO_FREE:
853 case PGO_CLEANIT|PGO_DEACTIVATE:
854 case PGO_DEACTIVATE:
855 deactivate_it:
856 /* skip the page if it's loaned or wired */
857 if (pg->loan_count != 0 || pg->wire_count != 0)
858 continue;
859
860 /* ...and deactivate the page. */
861 pmap_clear_reference(pg);
862 uvm_pagedeactivate(pg);
863 continue;
864
865 case PGO_FREE:
866
867 /*
868 * If there are multiple references to
869 * the object, just deactivate the page.
870 */
871
872 if (uobj->uo_refs > 1)
873 goto deactivate_it;
874
875 /* XXX skip the page if it's loaned or wired */
876 if (pg->loan_count != 0 || pg->wire_count != 0)
877 continue;
878
879 /*
880 * wait and try again if the page is busy.
881 * otherwise free the swap slot and the page.
882 */
883
884 pmap_page_protect(pg, VM_PROT_NONE);
885 if (pg->flags & PG_BUSY) {
886 if (by_list) {
887 TAILQ_INSERT_BEFORE(pg, &curmp, listq);
888 }
889 pg->flags |= PG_WANTED;
890 uvm_unlock_pageq();
891 UVM_UNLOCK_AND_WAIT(pg, &uobj->vmobjlock, 0,
892 "uao_put", 0);
893 simple_lock(&uobj->vmobjlock);
894 uvm_lock_pageq();
895 if (by_list) {
896 nextpg = TAILQ_NEXT(&curmp, listq);
897 TAILQ_REMOVE(&uobj->memq, &curmp,
898 listq);
899 } else
900 curoff -= PAGE_SIZE;
901 continue;
902 }
903 uao_dropswap(uobj, pg->offset >> PAGE_SHIFT);
904 uvm_pagefree(pg);
905 continue;
906 }
907 }
908 uvm_unlock_pageq();
909 if (by_list) {
910 TAILQ_REMOVE(&uobj->memq, &endmp, listq);
911 PRELE(curlwp);
912 }
913 simple_unlock(&uobj->vmobjlock);
914 return 0;
915 }
916
917 /*
918 * uao_get: fetch me a page
919 *
920 * we have three cases:
921 * 1: page is resident -> just return the page.
922 * 2: page is zero-fill -> allocate a new page and zero it.
923 * 3: page is swapped out -> fetch the page from swap.
924 *
925 * cases 1 and 2 can be handled with PGO_LOCKED, case 3 cannot.
926 * so, if the "center" page hits case 3 (or any page, with PGO_ALLPAGES),
927 * then we will need to return EBUSY.
928 *
929 * => prefer map unlocked (not required)
930 * => object must be locked! we will _unlock_ it before starting any I/O.
931 * => flags: PGO_ALLPAGES: get all of the pages
932 * PGO_LOCKED: fault data structures are locked
933 * => NOTE: offset is the offset of pps[0], _NOT_ pps[centeridx]
934 * => NOTE: caller must check for released pages!!
935 */
936
937 static int
938 uao_get(uobj, offset, pps, npagesp, centeridx, access_type, advice, flags)
939 struct uvm_object *uobj;
940 voff_t offset;
941 struct vm_page **pps;
942 int *npagesp;
943 int centeridx, advice, flags;
944 vm_prot_t access_type;
945 {
946 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj;
947 voff_t current_offset;
948 struct vm_page *ptmp = NULL; /* Quell compiler warning */
949 int lcv, gotpages, maxpages, swslot, error, pageidx;
950 boolean_t done;
951 UVMHIST_FUNC("uao_get"); UVMHIST_CALLED(pdhist);
952
953 UVMHIST_LOG(pdhist, "aobj=%p offset=%d, flags=%d",
954 aobj, offset, flags,0);
955
956 /*
957 * get number of pages
958 */
959
960 maxpages = *npagesp;
961
962 /*
963 * step 1: handled the case where fault data structures are locked.
964 */
965
966 if (flags & PGO_LOCKED) {
967
968 /*
969 * step 1a: get pages that are already resident. only do
970 * this if the data structures are locked (i.e. the first
971 * time through).
972 */
973
974 done = TRUE; /* be optimistic */
975 gotpages = 0; /* # of pages we got so far */
976 for (lcv = 0, current_offset = offset ; lcv < maxpages ;
977 lcv++, current_offset += PAGE_SIZE) {
978 /* do we care about this page? if not, skip it */
979 if (pps[lcv] == PGO_DONTCARE)
980 continue;
981 ptmp = uvm_pagelookup(uobj, current_offset);
982
983 /*
984 * if page is new, attempt to allocate the page,
985 * zero-fill'd.
986 */
987
988 if (ptmp == NULL && uao_find_swslot(&aobj->u_obj,
989 current_offset >> PAGE_SHIFT) == 0) {
990 ptmp = uvm_pagealloc(uobj, current_offset,
991 NULL, UVM_PGA_ZERO);
992 if (ptmp) {
993 /* new page */
994 ptmp->flags &= ~(PG_FAKE);
995 ptmp->pqflags |= PQ_AOBJ;
996 goto gotpage;
997 }
998 }
999
1000 /*
1001 * to be useful must get a non-busy page
1002 */
1003
1004 if (ptmp == NULL || (ptmp->flags & PG_BUSY) != 0) {
1005 if (lcv == centeridx ||
1006 (flags & PGO_ALLPAGES) != 0)
1007 /* need to do a wait or I/O! */
1008 done = FALSE;
1009 continue;
1010 }
1011
1012 /*
1013 * useful page: busy/lock it and plug it in our
1014 * result array
1015 */
1016
1017 /* caller must un-busy this page */
1018 ptmp->flags |= PG_BUSY;
1019 UVM_PAGE_OWN(ptmp, "uao_get1");
1020 gotpage:
1021 pps[lcv] = ptmp;
1022 gotpages++;
1023 }
1024
1025 /*
1026 * step 1b: now we've either done everything needed or we
1027 * to unlock and do some waiting or I/O.
1028 */
1029
1030 UVMHIST_LOG(pdhist, "<- done (done=%d)", done, 0,0,0);
1031 *npagesp = gotpages;
1032 if (done)
1033 return 0;
1034 else
1035 return EBUSY;
1036 }
1037
1038 /*
1039 * step 2: get non-resident or busy pages.
1040 * object is locked. data structures are unlocked.
1041 */
1042
1043 for (lcv = 0, current_offset = offset ; lcv < maxpages ;
1044 lcv++, current_offset += PAGE_SIZE) {
1045
1046 /*
1047 * - skip over pages we've already gotten or don't want
1048 * - skip over pages we don't _have_ to get
1049 */
1050
1051 if (pps[lcv] != NULL ||
1052 (lcv != centeridx && (flags & PGO_ALLPAGES) == 0))
1053 continue;
1054
1055 pageidx = current_offset >> PAGE_SHIFT;
1056
1057 /*
1058 * we have yet to locate the current page (pps[lcv]). we
1059 * first look for a page that is already at the current offset.
1060 * if we find a page, we check to see if it is busy or
1061 * released. if that is the case, then we sleep on the page
1062 * until it is no longer busy or released and repeat the lookup.
1063 * if the page we found is neither busy nor released, then we
1064 * busy it (so we own it) and plug it into pps[lcv]. this
1065 * 'break's the following while loop and indicates we are
1066 * ready to move on to the next page in the "lcv" loop above.
1067 *
1068 * if we exit the while loop with pps[lcv] still set to NULL,
1069 * then it means that we allocated a new busy/fake/clean page
1070 * ptmp in the object and we need to do I/O to fill in the data.
1071 */
1072
1073 /* top of "pps" while loop */
1074 while (pps[lcv] == NULL) {
1075 /* look for a resident page */
1076 ptmp = uvm_pagelookup(uobj, current_offset);
1077
1078 /* not resident? allocate one now (if we can) */
1079 if (ptmp == NULL) {
1080
1081 ptmp = uvm_pagealloc(uobj, current_offset,
1082 NULL, 0);
1083
1084 /* out of RAM? */
1085 if (ptmp == NULL) {
1086 simple_unlock(&uobj->vmobjlock);
1087 UVMHIST_LOG(pdhist,
1088 "sleeping, ptmp == NULL\n",0,0,0,0);
1089 uvm_wait("uao_getpage");
1090 simple_lock(&uobj->vmobjlock);
1091 continue;
1092 }
1093
1094 /*
1095 * safe with PQ's unlocked: because we just
1096 * alloc'd the page
1097 */
1098
1099 ptmp->pqflags |= PQ_AOBJ;
1100
1101 /*
1102 * got new page ready for I/O. break pps while
1103 * loop. pps[lcv] is still NULL.
1104 */
1105
1106 break;
1107 }
1108
1109 /* page is there, see if we need to wait on it */
1110 if ((ptmp->flags & PG_BUSY) != 0) {
1111 ptmp->flags |= PG_WANTED;
1112 UVMHIST_LOG(pdhist,
1113 "sleeping, ptmp->flags 0x%x\n",
1114 ptmp->flags,0,0,0);
1115 UVM_UNLOCK_AND_WAIT(ptmp, &uobj->vmobjlock,
1116 FALSE, "uao_get", 0);
1117 simple_lock(&uobj->vmobjlock);
1118 continue;
1119 }
1120
1121 /*
1122 * if we get here then the page has become resident and
1123 * unbusy between steps 1 and 2. we busy it now (so we
1124 * own it) and set pps[lcv] (so that we exit the while
1125 * loop).
1126 */
1127
1128 /* we own it, caller must un-busy */
1129 ptmp->flags |= PG_BUSY;
1130 UVM_PAGE_OWN(ptmp, "uao_get2");
1131 pps[lcv] = ptmp;
1132 }
1133
1134 /*
1135 * if we own the valid page at the correct offset, pps[lcv] will
1136 * point to it. nothing more to do except go to the next page.
1137 */
1138
1139 if (pps[lcv])
1140 continue; /* next lcv */
1141
1142 /*
1143 * we have a "fake/busy/clean" page that we just allocated.
1144 * do the needed "i/o", either reading from swap or zeroing.
1145 */
1146
1147 swslot = uao_find_swslot(&aobj->u_obj, pageidx);
1148
1149 /*
1150 * just zero the page if there's nothing in swap.
1151 */
1152
1153 if (swslot == 0) {
1154
1155 /*
1156 * page hasn't existed before, just zero it.
1157 */
1158
1159 uvm_pagezero(ptmp);
1160 } else {
1161 UVMHIST_LOG(pdhist, "pagein from swslot %d",
1162 swslot, 0,0,0);
1163
1164 /*
1165 * page in the swapped-out page.
1166 * unlock object for i/o, relock when done.
1167 */
1168
1169 simple_unlock(&uobj->vmobjlock);
1170 error = uvm_swap_get(ptmp, swslot, PGO_SYNCIO);
1171 simple_lock(&uobj->vmobjlock);
1172
1173 /*
1174 * I/O done. check for errors.
1175 */
1176
1177 if (error != 0) {
1178 UVMHIST_LOG(pdhist, "<- done (error=%d)",
1179 error,0,0,0);
1180 if (ptmp->flags & PG_WANTED)
1181 wakeup(ptmp);
1182
1183 /*
1184 * remove the swap slot from the aobj
1185 * and mark the aobj as having no real slot.
1186 * don't free the swap slot, thus preventing
1187 * it from being used again.
1188 */
1189
1190 swslot = uao_set_swslot(&aobj->u_obj, pageidx,
1191 SWSLOT_BAD);
1192 if (swslot > 0) {
1193 uvm_swap_markbad(swslot, 1);
1194 }
1195
1196 uvm_lock_pageq();
1197 uvm_pagefree(ptmp);
1198 uvm_unlock_pageq();
1199 simple_unlock(&uobj->vmobjlock);
1200 return error;
1201 }
1202 }
1203
1204 /*
1205 * we got the page! clear the fake flag (indicates valid
1206 * data now in page) and plug into our result array. note
1207 * that page is still busy.
1208 *
1209 * it is the callers job to:
1210 * => check if the page is released
1211 * => unbusy the page
1212 * => activate the page
1213 */
1214
1215 ptmp->flags &= ~PG_FAKE;
1216 pps[lcv] = ptmp;
1217 }
1218
1219 /*
1220 * finally, unlock object and return.
1221 */
1222
1223 simple_unlock(&uobj->vmobjlock);
1224 UVMHIST_LOG(pdhist, "<- done (OK)",0,0,0,0);
1225 return 0;
1226 }
1227
1228 /*
1229 * uao_dropswap: release any swap resources from this aobj page.
1230 *
1231 * => aobj must be locked or have a reference count of 0.
1232 */
1233
1234 void
1235 uao_dropswap(uobj, pageidx)
1236 struct uvm_object *uobj;
1237 int pageidx;
1238 {
1239 int slot;
1240
1241 slot = uao_set_swslot(uobj, pageidx, 0);
1242 if (slot) {
1243 uvm_swap_free(slot, 1);
1244 }
1245 }
1246
1247 /*
1248 * page in every page in every aobj that is paged-out to a range of swslots.
1249 *
1250 * => nothing should be locked.
1251 * => returns TRUE if pagein was aborted due to lack of memory.
1252 */
1253
1254 boolean_t
1255 uao_swap_off(startslot, endslot)
1256 int startslot, endslot;
1257 {
1258 struct uvm_aobj *aobj, *nextaobj;
1259 boolean_t rv;
1260
1261 /*
1262 * walk the list of all aobjs.
1263 */
1264
1265 restart:
1266 simple_lock(&uao_list_lock);
1267 for (aobj = LIST_FIRST(&uao_list);
1268 aobj != NULL;
1269 aobj = nextaobj) {
1270
1271 /*
1272 * try to get the object lock, start all over if we fail.
1273 * most of the time we'll get the aobj lock,
1274 * so this should be a rare case.
1275 */
1276
1277 if (!simple_lock_try(&aobj->u_obj.vmobjlock)) {
1278 simple_unlock(&uao_list_lock);
1279 goto restart;
1280 }
1281
1282 /*
1283 * add a ref to the aobj so it doesn't disappear
1284 * while we're working.
1285 */
1286
1287 uao_reference_locked(&aobj->u_obj);
1288
1289 /*
1290 * now it's safe to unlock the uao list.
1291 */
1292
1293 simple_unlock(&uao_list_lock);
1294
1295 /*
1296 * page in any pages in the swslot range.
1297 * if there's an error, abort and return the error.
1298 */
1299
1300 rv = uao_pagein(aobj, startslot, endslot);
1301 if (rv) {
1302 uao_detach_locked(&aobj->u_obj);
1303 return rv;
1304 }
1305
1306 /*
1307 * we're done with this aobj.
1308 * relock the list and drop our ref on the aobj.
1309 */
1310
1311 simple_lock(&uao_list_lock);
1312 nextaobj = LIST_NEXT(aobj, u_list);
1313 uao_detach_locked(&aobj->u_obj);
1314 }
1315
1316 /*
1317 * done with traversal, unlock the list
1318 */
1319 simple_unlock(&uao_list_lock);
1320 return FALSE;
1321 }
1322
1323
1324 /*
1325 * page in any pages from aobj in the given range.
1326 *
1327 * => aobj must be locked and is returned locked.
1328 * => returns TRUE if pagein was aborted due to lack of memory.
1329 */
1330 static boolean_t
1331 uao_pagein(aobj, startslot, endslot)
1332 struct uvm_aobj *aobj;
1333 int startslot, endslot;
1334 {
1335 boolean_t rv;
1336
1337 if (UAO_USES_SWHASH(aobj)) {
1338 struct uao_swhash_elt *elt;
1339 int bucket;
1340
1341 restart:
1342 for (bucket = aobj->u_swhashmask; bucket >= 0; bucket--) {
1343 for (elt = LIST_FIRST(&aobj->u_swhash[bucket]);
1344 elt != NULL;
1345 elt = LIST_NEXT(elt, list)) {
1346 int i;
1347
1348 for (i = 0; i < UAO_SWHASH_CLUSTER_SIZE; i++) {
1349 int slot = elt->slots[i];
1350
1351 /*
1352 * if the slot isn't in range, skip it.
1353 */
1354
1355 if (slot < startslot ||
1356 slot >= endslot) {
1357 continue;
1358 }
1359
1360 /*
1361 * process the page,
1362 * the start over on this object
1363 * since the swhash elt
1364 * may have been freed.
1365 */
1366
1367 rv = uao_pagein_page(aobj,
1368 UAO_SWHASH_ELT_PAGEIDX_BASE(elt) + i);
1369 if (rv) {
1370 return rv;
1371 }
1372 goto restart;
1373 }
1374 }
1375 }
1376 } else {
1377 int i;
1378
1379 for (i = 0; i < aobj->u_pages; i++) {
1380 int slot = aobj->u_swslots[i];
1381
1382 /*
1383 * if the slot isn't in range, skip it
1384 */
1385
1386 if (slot < startslot || slot >= endslot) {
1387 continue;
1388 }
1389
1390 /*
1391 * process the page.
1392 */
1393
1394 rv = uao_pagein_page(aobj, i);
1395 if (rv) {
1396 return rv;
1397 }
1398 }
1399 }
1400
1401 return FALSE;
1402 }
1403
1404 /*
1405 * page in a page from an aobj. used for swap_off.
1406 * returns TRUE if pagein was aborted due to lack of memory.
1407 *
1408 * => aobj must be locked and is returned locked.
1409 */
1410
1411 static boolean_t
1412 uao_pagein_page(aobj, pageidx)
1413 struct uvm_aobj *aobj;
1414 int pageidx;
1415 {
1416 struct vm_page *pg;
1417 int rv, npages;
1418
1419 pg = NULL;
1420 npages = 1;
1421 /* locked: aobj */
1422 rv = uao_get(&aobj->u_obj, pageidx << PAGE_SHIFT,
1423 &pg, &npages, 0, VM_PROT_READ|VM_PROT_WRITE, 0, 0);
1424 /* unlocked: aobj */
1425
1426 /*
1427 * relock and finish up.
1428 */
1429
1430 simple_lock(&aobj->u_obj.vmobjlock);
1431 switch (rv) {
1432 case 0:
1433 break;
1434
1435 case EIO:
1436 case ERESTART:
1437
1438 /*
1439 * nothing more to do on errors.
1440 * ERESTART can only mean that the anon was freed,
1441 * so again there's nothing to do.
1442 */
1443
1444 return FALSE;
1445
1446 default:
1447 return TRUE;
1448 }
1449
1450 /*
1451 * ok, we've got the page now.
1452 * mark it as dirty, clear its swslot and un-busy it.
1453 */
1454 uao_dropswap(&aobj->u_obj, pageidx);
1455
1456 /*
1457 * deactivate the page (to make sure it's on a page queue).
1458 */
1459 uvm_lock_pageq();
1460 if (pg->wire_count == 0)
1461 uvm_pagedeactivate(pg);
1462 uvm_unlock_pageq();
1463
1464 if (pg->flags & PG_WANTED) {
1465 wakeup(pg);
1466 }
1467 pg->flags &= ~(PG_WANTED|PG_BUSY|PG_CLEAN|PG_FAKE);
1468 UVM_PAGE_OWN(pg, NULL);
1469
1470 return FALSE;
1471 }
Cache object: 568fdb20930c79935339e2ca565a1147
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