FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_fault.c
1 /*
2 * (MPSAFE)
3 *
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 * Copyright (c) 1994 John S. Dyson
7 * All rights reserved.
8 * Copyright (c) 1994 David Greenman
9 * All rights reserved.
10 *
11 *
12 * This code is derived from software contributed to Berkeley by
13 * The Mach Operating System project at Carnegie-Mellon University.
14 *
15 * Redistribution and use in source and binary forms, with or without
16 * modification, are permitted provided that the following conditions
17 * are met:
18 * 1. Redistributions of source code must retain the above copyright
19 * notice, this list of conditions and the following disclaimer.
20 * 2. Redistributions in binary form must reproduce the above copyright
21 * notice, this list of conditions and the following disclaimer in the
22 * documentation and/or other materials provided with the distribution.
23 * 3. Neither the name of the University nor the names of its contributors
24 * may be used to endorse or promote products derived from this software
25 * without specific prior written permission.
26 *
27 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 * SUCH DAMAGE.
38 *
39 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94
40 *
41 *
42 * Copyright (c) 1987, 1990 Carnegie-Mellon University.
43 * All rights reserved.
44 *
45 * Authors: Avadis Tevanian, Jr., Michael Wayne Young
46 *
47 * Permission to use, copy, modify and distribute this software and
48 * its documentation is hereby granted, provided that both the copyright
49 * notice and this permission notice appear in all copies of the
50 * software, derivative works or modified versions, and any portions
51 * thereof, and that both notices appear in supporting documentation.
52 *
53 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
54 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
55 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
56 *
57 * Carnegie Mellon requests users of this software to return to
58 *
59 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
60 * School of Computer Science
61 * Carnegie Mellon University
62 * Pittsburgh PA 15213-3890
63 *
64 * any improvements or extensions that they make and grant Carnegie the
65 * rights to redistribute these changes.
66 *
67 * $FreeBSD: src/sys/vm/vm_fault.c,v 1.108.2.8 2002/02/26 05:49:27 silby Exp $
68 * $DragonFly: src/sys/vm/vm_fault.c,v 1.47 2008/07/01 02:02:56 dillon Exp $
69 */
70
71 /*
72 * Page fault handling module.
73 */
74
75 #include <sys/param.h>
76 #include <sys/systm.h>
77 #include <sys/kernel.h>
78 #include <sys/proc.h>
79 #include <sys/vnode.h>
80 #include <sys/resourcevar.h>
81 #include <sys/vmmeter.h>
82 #include <sys/vkernel.h>
83 #include <sys/lock.h>
84 #include <sys/sysctl.h>
85
86 #include <cpu/lwbuf.h>
87
88 #include <vm/vm.h>
89 #include <vm/vm_param.h>
90 #include <vm/pmap.h>
91 #include <vm/vm_map.h>
92 #include <vm/vm_object.h>
93 #include <vm/vm_page.h>
94 #include <vm/vm_pageout.h>
95 #include <vm/vm_kern.h>
96 #include <vm/vm_pager.h>
97 #include <vm/vnode_pager.h>
98 #include <vm/vm_extern.h>
99
100 #include <sys/thread2.h>
101 #include <vm/vm_page2.h>
102
103 struct faultstate {
104 vm_page_t m;
105 vm_object_t object;
106 vm_pindex_t pindex;
107 vm_prot_t prot;
108 vm_page_t first_m;
109 vm_object_t first_object;
110 vm_prot_t first_prot;
111 vm_map_t map;
112 vm_map_entry_t entry;
113 int lookup_still_valid;
114 int hardfault;
115 int fault_flags;
116 int map_generation;
117 int shared;
118 int first_shared;
119 boolean_t wired;
120 struct vnode *vp;
121 };
122
123 static int debug_cluster = 0;
124 SYSCTL_INT(_vm, OID_AUTO, debug_cluster, CTLFLAG_RW, &debug_cluster, 0, "");
125 int vm_shared_fault = 1;
126 TUNABLE_INT("vm.shared_fault", &vm_shared_fault);
127 SYSCTL_INT(_vm, OID_AUTO, shared_fault, CTLFLAG_RW, &vm_shared_fault, 0,
128 "Allow shared token on vm_object");
129 static long vm_shared_hit = 0;
130 SYSCTL_LONG(_vm, OID_AUTO, shared_hit, CTLFLAG_RW, &vm_shared_hit, 0,
131 "Successful shared faults");
132 static long vm_shared_count = 0;
133 SYSCTL_LONG(_vm, OID_AUTO, shared_count, CTLFLAG_RW, &vm_shared_count, 0,
134 "Shared fault attempts");
135 static long vm_shared_miss = 0;
136 SYSCTL_LONG(_vm, OID_AUTO, shared_miss, CTLFLAG_RW, &vm_shared_miss, 0,
137 "Unsuccessful shared faults");
138
139 static int vm_fault_object(struct faultstate *, vm_pindex_t, vm_prot_t, int);
140 static int vm_fault_vpagetable(struct faultstate *, vm_pindex_t *,
141 vpte_t, int, int);
142 #if 0
143 static int vm_fault_additional_pages (vm_page_t, int, int, vm_page_t *, int *);
144 #endif
145 static void vm_set_nosync(vm_page_t m, vm_map_entry_t entry);
146 static void vm_prefault(pmap_t pmap, vm_offset_t addra,
147 vm_map_entry_t entry, int prot, int fault_flags);
148 static void vm_prefault_quick(pmap_t pmap, vm_offset_t addra,
149 vm_map_entry_t entry, int prot, int fault_flags);
150
151 static __inline void
152 release_page(struct faultstate *fs)
153 {
154 vm_page_deactivate(fs->m);
155 vm_page_wakeup(fs->m);
156 fs->m = NULL;
157 }
158
159 /*
160 * NOTE: Once unlocked any cached fs->entry becomes invalid, any reuse
161 * requires relocking and then checking the timestamp.
162 *
163 * NOTE: vm_map_lock_read() does not bump fs->map->timestamp so we do
164 * not have to update fs->map_generation here.
165 *
166 * NOTE: This function can fail due to a deadlock against the caller's
167 * holding of a vm_page BUSY.
168 */
169 static __inline int
170 relock_map(struct faultstate *fs)
171 {
172 int error;
173
174 if (fs->lookup_still_valid == FALSE && fs->map) {
175 error = vm_map_lock_read_to(fs->map);
176 if (error == 0)
177 fs->lookup_still_valid = TRUE;
178 } else {
179 error = 0;
180 }
181 return error;
182 }
183
184 static __inline void
185 unlock_map(struct faultstate *fs)
186 {
187 if (fs->lookup_still_valid && fs->map) {
188 vm_map_lookup_done(fs->map, fs->entry, 0);
189 fs->lookup_still_valid = FALSE;
190 }
191 }
192
193 /*
194 * Clean up after a successful call to vm_fault_object() so another call
195 * to vm_fault_object() can be made.
196 */
197 static void
198 _cleanup_successful_fault(struct faultstate *fs, int relock)
199 {
200 /*
201 * We allocated a junk page for a COW operation that did
202 * not occur, the page must be freed.
203 */
204 if (fs->object != fs->first_object) {
205 KKASSERT(fs->first_shared == 0);
206 vm_page_free(fs->first_m);
207 vm_object_pip_wakeup(fs->object);
208 fs->first_m = NULL;
209 }
210
211 /*
212 * Reset fs->object.
213 */
214 fs->object = fs->first_object;
215 if (relock && fs->lookup_still_valid == FALSE) {
216 if (fs->map)
217 vm_map_lock_read(fs->map);
218 fs->lookup_still_valid = TRUE;
219 }
220 }
221
222 static void
223 _unlock_things(struct faultstate *fs, int dealloc)
224 {
225 _cleanup_successful_fault(fs, 0);
226 if (dealloc) {
227 /*vm_object_deallocate(fs->first_object);*/
228 /*fs->first_object = NULL; drop used later on */
229 }
230 unlock_map(fs);
231 if (fs->vp != NULL) {
232 vput(fs->vp);
233 fs->vp = NULL;
234 }
235 }
236
237 #define unlock_things(fs) _unlock_things(fs, 0)
238 #define unlock_and_deallocate(fs) _unlock_things(fs, 1)
239 #define cleanup_successful_fault(fs) _cleanup_successful_fault(fs, 1)
240
241 /*
242 * TRYPAGER
243 *
244 * Determine if the pager for the current object *might* contain the page.
245 *
246 * We only need to try the pager if this is not a default object (default
247 * objects are zero-fill and have no real pager), and if we are not taking
248 * a wiring fault or if the FS entry is wired.
249 */
250 #define TRYPAGER(fs) \
251 (fs->object->type != OBJT_DEFAULT && \
252 (((fs->fault_flags & VM_FAULT_WIRE_MASK) == 0) || fs->wired))
253
254 /*
255 * vm_fault:
256 *
257 * Handle a page fault occuring at the given address, requiring the given
258 * permissions, in the map specified. If successful, the page is inserted
259 * into the associated physical map.
260 *
261 * NOTE: The given address should be truncated to the proper page address.
262 *
263 * KERN_SUCCESS is returned if the page fault is handled; otherwise,
264 * a standard error specifying why the fault is fatal is returned.
265 *
266 * The map in question must be referenced, and remains so.
267 * The caller may hold no locks.
268 * No other requirements.
269 */
270 int
271 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags)
272 {
273 int result;
274 vm_pindex_t first_pindex;
275 struct faultstate fs;
276 struct lwp *lp;
277 int growstack;
278 int retry = 0;
279
280 vm_page_pcpu_cache();
281 fs.hardfault = 0;
282 fs.fault_flags = fault_flags;
283 fs.vp = NULL;
284 fs.shared = vm_shared_fault;
285 fs.first_shared = vm_shared_fault;
286 growstack = 1;
287 if (vm_shared_fault)
288 ++vm_shared_count;
289
290 /*
291 * vm_map interactions
292 */
293 if ((lp = curthread->td_lwp) != NULL)
294 lp->lwp_flags |= LWP_PAGING;
295 lwkt_gettoken(&map->token);
296
297 RetryFault:
298 /*
299 * Find the vm_map_entry representing the backing store and resolve
300 * the top level object and page index. This may have the side
301 * effect of executing a copy-on-write on the map entry and/or
302 * creating a shadow object, but will not COW any actual VM pages.
303 *
304 * On success fs.map is left read-locked and various other fields
305 * are initialized but not otherwise referenced or locked.
306 *
307 * NOTE! vm_map_lookup will try to upgrade the fault_type to
308 * VM_FAULT_WRITE if the map entry is a virtual page table and also
309 * writable, so we can set the 'A'accessed bit in the virtual page
310 * table entry.
311 */
312 fs.map = map;
313 result = vm_map_lookup(&fs.map, vaddr, fault_type,
314 &fs.entry, &fs.first_object,
315 &first_pindex, &fs.first_prot, &fs.wired);
316
317 /*
318 * If the lookup failed or the map protections are incompatible,
319 * the fault generally fails. However, if the caller is trying
320 * to do a user wiring we have more work to do.
321 */
322 if (result != KERN_SUCCESS) {
323 if (result != KERN_PROTECTION_FAILURE ||
324 (fs.fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE)
325 {
326 if (result == KERN_INVALID_ADDRESS && growstack &&
327 map != &kernel_map && curproc != NULL) {
328 result = vm_map_growstack(curproc, vaddr);
329 if (result == KERN_SUCCESS) {
330 growstack = 0;
331 ++retry;
332 goto RetryFault;
333 }
334 result = KERN_FAILURE;
335 }
336 goto done;
337 }
338
339 /*
340 * If we are user-wiring a r/w segment, and it is COW, then
341 * we need to do the COW operation. Note that we don't
342 * currently COW RO sections now, because it is NOT desirable
343 * to COW .text. We simply keep .text from ever being COW'ed
344 * and take the heat that one cannot debug wired .text sections.
345 */
346 result = vm_map_lookup(&fs.map, vaddr,
347 VM_PROT_READ|VM_PROT_WRITE|
348 VM_PROT_OVERRIDE_WRITE,
349 &fs.entry, &fs.first_object,
350 &first_pindex, &fs.first_prot,
351 &fs.wired);
352 if (result != KERN_SUCCESS) {
353 result = KERN_FAILURE;
354 goto done;
355 }
356
357 /*
358 * If we don't COW now, on a user wire, the user will never
359 * be able to write to the mapping. If we don't make this
360 * restriction, the bookkeeping would be nearly impossible.
361 *
362 * XXX We have a shared lock, this will have a MP race but
363 * I don't see how it can hurt anything.
364 */
365 if ((fs.entry->protection & VM_PROT_WRITE) == 0)
366 fs.entry->max_protection &= ~VM_PROT_WRITE;
367 }
368
369 /*
370 * fs.map is read-locked
371 *
372 * Misc checks. Save the map generation number to detect races.
373 */
374 fs.map_generation = fs.map->timestamp;
375 fs.lookup_still_valid = TRUE;
376 fs.first_m = NULL;
377 fs.object = fs.first_object; /* so unlock_and_deallocate works */
378
379 if (fs.entry->eflags & (MAP_ENTRY_NOFAULT | MAP_ENTRY_KSTACK)) {
380 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
381 panic("vm_fault: fault on nofault entry, addr: %p",
382 (void *)vaddr);
383 }
384 if ((fs.entry->eflags & MAP_ENTRY_KSTACK) &&
385 vaddr >= fs.entry->start &&
386 vaddr < fs.entry->start + PAGE_SIZE) {
387 panic("vm_fault: fault on stack guard, addr: %p",
388 (void *)vaddr);
389 }
390 }
391
392 /*
393 * A system map entry may return a NULL object. No object means
394 * no pager means an unrecoverable kernel fault.
395 */
396 if (fs.first_object == NULL) {
397 panic("vm_fault: unrecoverable fault at %p in entry %p",
398 (void *)vaddr, fs.entry);
399 }
400
401 /*
402 * Fail here if not a trivial anonymous page fault and TDF_NOFAULT
403 * is set.
404 */
405 if ((curthread->td_flags & TDF_NOFAULT) &&
406 (retry ||
407 fs.first_object->type == OBJT_VNODE ||
408 fs.first_object->backing_object)) {
409 result = KERN_FAILURE;
410 unlock_things(&fs);
411 goto done2;
412 }
413
414 /*
415 * If the entry is wired we cannot change the page protection.
416 */
417 if (fs.wired)
418 fault_type = fs.first_prot;
419
420 /*
421 * We generally want to avoid unnecessary exclusive modes on backing
422 * and terminal objects because this can seriously interfere with
423 * heavily fork()'d processes (particularly /bin/sh scripts).
424 *
425 * However, we also want to avoid unnecessary retries due to needed
426 * shared->exclusive promotion for common faults. Exclusive mode is
427 * always needed if any page insertion, rename, or free occurs in an
428 * object (and also indirectly if any I/O is done).
429 *
430 * The main issue here is going to be fs.first_shared. If the
431 * first_object has a backing object which isn't shadowed and the
432 * process is single-threaded we might as well use an exclusive
433 * lock/chain right off the bat.
434 */
435 if (fs.first_shared && fs.first_object->backing_object &&
436 LIST_EMPTY(&fs.first_object->shadow_head) &&
437 curthread->td_proc && curthread->td_proc->p_nthreads == 1) {
438 fs.first_shared = 0;
439 }
440
441 /*
442 * swap_pager_unswapped() needs an exclusive object
443 */
444 if (fault_flags & (VM_FAULT_UNSWAP | VM_FAULT_DIRTY)) {
445 fs.first_shared = 0;
446 }
447
448 /*
449 * Obtain a top-level object lock, shared or exclusive depending
450 * on fs.first_shared. If a shared lock winds up being insufficient
451 * we will retry with an exclusive lock.
452 *
453 * The vnode pager lock is always shared.
454 */
455 if (fs.first_shared)
456 vm_object_hold_shared(fs.first_object);
457 else
458 vm_object_hold(fs.first_object);
459 if (fs.vp == NULL)
460 fs.vp = vnode_pager_lock(fs.first_object);
461
462 /*
463 * The page we want is at (first_object, first_pindex), but if the
464 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the
465 * page table to figure out the actual pindex.
466 *
467 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION
468 * ONLY
469 */
470 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
471 result = vm_fault_vpagetable(&fs, &first_pindex,
472 fs.entry->aux.master_pde,
473 fault_type, 1);
474 if (result == KERN_TRY_AGAIN) {
475 vm_object_drop(fs.first_object);
476 ++retry;
477 goto RetryFault;
478 }
479 if (result != KERN_SUCCESS)
480 goto done;
481 }
482
483 /*
484 * Now we have the actual (object, pindex), fault in the page. If
485 * vm_fault_object() fails it will unlock and deallocate the FS
486 * data. If it succeeds everything remains locked and fs->object
487 * will have an additional PIP count if it is not equal to
488 * fs->first_object
489 *
490 * vm_fault_object will set fs->prot for the pmap operation. It is
491 * allowed to set VM_PROT_WRITE if fault_type == VM_PROT_READ if the
492 * page can be safely written. However, it will force a read-only
493 * mapping for a read fault if the memory is managed by a virtual
494 * page table.
495 *
496 * If the fault code uses the shared object lock shortcut
497 * we must not try to burst (we can't allocate VM pages).
498 */
499 result = vm_fault_object(&fs, first_pindex, fault_type, 1);
500 if (result == KERN_TRY_AGAIN) {
501 vm_object_drop(fs.first_object);
502 ++retry;
503 goto RetryFault;
504 }
505 if (result != KERN_SUCCESS)
506 goto done;
507
508 /*
509 * On success vm_fault_object() does not unlock or deallocate, and fs.m
510 * will contain a busied page.
511 *
512 * Enter the page into the pmap and do pmap-related adjustments.
513 */
514 KKASSERT(fs.lookup_still_valid == TRUE);
515 vm_page_flag_set(fs.m, PG_REFERENCED);
516 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired, fs.entry);
517 mycpu->gd_cnt.v_vm_faults++;
518 if (curthread->td_lwp)
519 ++curthread->td_lwp->lwp_ru.ru_minflt;
520
521 /*KKASSERT(fs.m->queue == PQ_NONE); page-in op may deactivate page */
522 KKASSERT(fs.m->flags & PG_BUSY);
523
524 /*
525 * If the page is not wired down, then put it where the pageout daemon
526 * can find it.
527 */
528 if (fs.fault_flags & VM_FAULT_WIRE_MASK) {
529 if (fs.wired)
530 vm_page_wire(fs.m);
531 else
532 vm_page_unwire(fs.m, 1);
533 } else {
534 vm_page_activate(fs.m);
535 }
536 vm_page_wakeup(fs.m);
537
538 /*
539 * Burst in a few more pages if possible. The fs.map should still
540 * be locked. To avoid interlocking against a vnode->getblk
541 * operation we had to be sure to unbusy our primary vm_page above
542 * first.
543 *
544 * A normal burst can continue down backing store, only execute
545 * if we are holding an exclusive lock, otherwise the exclusive
546 * locks the burst code gets might cause excessive SMP collisions.
547 *
548 * A quick burst can be utilized when there is no backing object
549 * (i.e. a shared file mmap).
550 */
551 if ((fault_flags & VM_FAULT_BURST) &&
552 (fs.fault_flags & VM_FAULT_WIRE_MASK) == 0 &&
553 fs.wired == 0) {
554 if (fs.first_shared == 0 && fs.shared == 0) {
555 vm_prefault(fs.map->pmap, vaddr,
556 fs.entry, fs.prot, fault_flags);
557 } else {
558 vm_prefault_quick(fs.map->pmap, vaddr,
559 fs.entry, fs.prot, fault_flags);
560 }
561 }
562
563 /*
564 * Unlock everything, and return
565 */
566 unlock_things(&fs);
567
568 if (curthread->td_lwp) {
569 if (fs.hardfault) {
570 curthread->td_lwp->lwp_ru.ru_majflt++;
571 } else {
572 curthread->td_lwp->lwp_ru.ru_minflt++;
573 }
574 }
575
576 /*vm_object_deallocate(fs.first_object);*/
577 /*fs.m = NULL; */
578 /*fs.first_object = NULL; must still drop later */
579
580 result = KERN_SUCCESS;
581 done:
582 if (fs.first_object)
583 vm_object_drop(fs.first_object);
584 done2:
585 lwkt_reltoken(&map->token);
586 if (lp)
587 lp->lwp_flags &= ~LWP_PAGING;
588 if (vm_shared_fault && fs.shared == 0)
589 ++vm_shared_miss;
590 return (result);
591 }
592
593 /*
594 * Fault in the specified virtual address in the current process map,
595 * returning a held VM page or NULL. See vm_fault_page() for more
596 * information.
597 *
598 * No requirements.
599 */
600 vm_page_t
601 vm_fault_page_quick(vm_offset_t va, vm_prot_t fault_type, int *errorp)
602 {
603 struct lwp *lp = curthread->td_lwp;
604 vm_page_t m;
605
606 m = vm_fault_page(&lp->lwp_vmspace->vm_map, va,
607 fault_type, VM_FAULT_NORMAL, errorp);
608 return(m);
609 }
610
611 /*
612 * Fault in the specified virtual address in the specified map, doing all
613 * necessary manipulation of the object store and all necessary I/O. Return
614 * a held VM page or NULL, and set *errorp. The related pmap is not
615 * updated.
616 *
617 * The returned page will be properly dirtied if VM_PROT_WRITE was specified,
618 * and marked PG_REFERENCED as well.
619 *
620 * If the page cannot be faulted writable and VM_PROT_WRITE was specified, an
621 * error will be returned.
622 *
623 * No requirements.
624 */
625 vm_page_t
626 vm_fault_page(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
627 int fault_flags, int *errorp)
628 {
629 vm_pindex_t first_pindex;
630 struct faultstate fs;
631 int result;
632 int retry = 0;
633 vm_prot_t orig_fault_type = fault_type;
634
635 fs.hardfault = 0;
636 fs.fault_flags = fault_flags;
637 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0);
638
639 /*
640 * Dive the pmap (concurrency possible). If we find the
641 * appropriate page we can terminate early and quickly.
642 */
643 fs.m = pmap_fault_page_quick(map->pmap, vaddr, fault_type);
644 if (fs.m) {
645 *errorp = 0;
646 return(fs.m);
647 }
648
649 /*
650 * Otherwise take a concurrency hit and do a formal page
651 * fault.
652 */
653 fs.shared = vm_shared_fault;
654 fs.first_shared = vm_shared_fault;
655 fs.vp = NULL;
656 lwkt_gettoken(&map->token);
657
658 /*
659 * swap_pager_unswapped() needs an exclusive object
660 */
661 if (fault_flags & (VM_FAULT_UNSWAP | VM_FAULT_DIRTY)) {
662 fs.first_shared = 0;
663 }
664
665 RetryFault:
666 /*
667 * Find the vm_map_entry representing the backing store and resolve
668 * the top level object and page index. This may have the side
669 * effect of executing a copy-on-write on the map entry and/or
670 * creating a shadow object, but will not COW any actual VM pages.
671 *
672 * On success fs.map is left read-locked and various other fields
673 * are initialized but not otherwise referenced or locked.
674 *
675 * NOTE! vm_map_lookup will upgrade the fault_type to VM_FAULT_WRITE
676 * if the map entry is a virtual page table and also writable,
677 * so we can set the 'A'accessed bit in the virtual page table entry.
678 */
679 fs.map = map;
680 result = vm_map_lookup(&fs.map, vaddr, fault_type,
681 &fs.entry, &fs.first_object,
682 &first_pindex, &fs.first_prot, &fs.wired);
683
684 if (result != KERN_SUCCESS) {
685 *errorp = result;
686 fs.m = NULL;
687 goto done;
688 }
689
690 /*
691 * fs.map is read-locked
692 *
693 * Misc checks. Save the map generation number to detect races.
694 */
695 fs.map_generation = fs.map->timestamp;
696 fs.lookup_still_valid = TRUE;
697 fs.first_m = NULL;
698 fs.object = fs.first_object; /* so unlock_and_deallocate works */
699
700 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) {
701 panic("vm_fault: fault on nofault entry, addr: %lx",
702 (u_long)vaddr);
703 }
704
705 /*
706 * A system map entry may return a NULL object. No object means
707 * no pager means an unrecoverable kernel fault.
708 */
709 if (fs.first_object == NULL) {
710 panic("vm_fault: unrecoverable fault at %p in entry %p",
711 (void *)vaddr, fs.entry);
712 }
713
714 /*
715 * Fail here if not a trivial anonymous page fault and TDF_NOFAULT
716 * is set.
717 */
718 if ((curthread->td_flags & TDF_NOFAULT) &&
719 (retry ||
720 fs.first_object->type == OBJT_VNODE ||
721 fs.first_object->backing_object)) {
722 *errorp = KERN_FAILURE;
723 unlock_things(&fs);
724 goto done2;
725 }
726
727 /*
728 * If the entry is wired we cannot change the page protection.
729 */
730 if (fs.wired)
731 fault_type = fs.first_prot;
732
733 /*
734 * Make a reference to this object to prevent its disposal while we
735 * are messing with it. Once we have the reference, the map is free
736 * to be diddled. Since objects reference their shadows (and copies),
737 * they will stay around as well.
738 *
739 * The reference should also prevent an unexpected collapse of the
740 * parent that might move pages from the current object into the
741 * parent unexpectedly, resulting in corruption.
742 *
743 * Bump the paging-in-progress count to prevent size changes (e.g.
744 * truncation operations) during I/O. This must be done after
745 * obtaining the vnode lock in order to avoid possible deadlocks.
746 */
747 if (fs.first_shared)
748 vm_object_hold_shared(fs.first_object);
749 else
750 vm_object_hold(fs.first_object);
751 if (fs.vp == NULL)
752 fs.vp = vnode_pager_lock(fs.first_object); /* shared */
753
754 /*
755 * The page we want is at (first_object, first_pindex), but if the
756 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the
757 * page table to figure out the actual pindex.
758 *
759 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION
760 * ONLY
761 */
762 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
763 result = vm_fault_vpagetable(&fs, &first_pindex,
764 fs.entry->aux.master_pde,
765 fault_type, 1);
766 if (result == KERN_TRY_AGAIN) {
767 vm_object_drop(fs.first_object);
768 ++retry;
769 goto RetryFault;
770 }
771 if (result != KERN_SUCCESS) {
772 *errorp = result;
773 fs.m = NULL;
774 goto done;
775 }
776 }
777
778 /*
779 * Now we have the actual (object, pindex), fault in the page. If
780 * vm_fault_object() fails it will unlock and deallocate the FS
781 * data. If it succeeds everything remains locked and fs->object
782 * will have an additinal PIP count if it is not equal to
783 * fs->first_object
784 */
785 fs.m = NULL;
786 result = vm_fault_object(&fs, first_pindex, fault_type, 1);
787
788 if (result == KERN_TRY_AGAIN) {
789 vm_object_drop(fs.first_object);
790 ++retry;
791 goto RetryFault;
792 }
793 if (result != KERN_SUCCESS) {
794 *errorp = result;
795 fs.m = NULL;
796 goto done;
797 }
798
799 if ((orig_fault_type & VM_PROT_WRITE) &&
800 (fs.prot & VM_PROT_WRITE) == 0) {
801 *errorp = KERN_PROTECTION_FAILURE;
802 unlock_and_deallocate(&fs);
803 fs.m = NULL;
804 goto done;
805 }
806
807 /*
808 * DO NOT UPDATE THE PMAP!!! This function may be called for
809 * a pmap unrelated to the current process pmap, in which case
810 * the current cpu core will not be listed in the pmap's pm_active
811 * mask. Thus invalidation interlocks will fail to work properly.
812 *
813 * (for example, 'ps' uses procfs to read program arguments from
814 * each process's stack).
815 *
816 * In addition to the above this function will be called to acquire
817 * a page that might already be faulted in, re-faulting it
818 * continuously is a waste of time.
819 *
820 * XXX could this have been the cause of our random seg-fault
821 * issues? procfs accesses user stacks.
822 */
823 vm_page_flag_set(fs.m, PG_REFERENCED);
824 #if 0
825 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired, NULL);
826 mycpu->gd_cnt.v_vm_faults++;
827 if (curthread->td_lwp)
828 ++curthread->td_lwp->lwp_ru.ru_minflt;
829 #endif
830
831 /*
832 * On success vm_fault_object() does not unlock or deallocate, and fs.m
833 * will contain a busied page. So we must unlock here after having
834 * messed with the pmap.
835 */
836 unlock_things(&fs);
837
838 /*
839 * Return a held page. We are not doing any pmap manipulation so do
840 * not set PG_MAPPED. However, adjust the page flags according to
841 * the fault type because the caller may not use a managed pmapping
842 * (so we don't want to lose the fact that the page will be dirtied
843 * if a write fault was specified).
844 */
845 vm_page_hold(fs.m);
846 vm_page_activate(fs.m);
847 if (fault_type & VM_PROT_WRITE)
848 vm_page_dirty(fs.m);
849
850 if (curthread->td_lwp) {
851 if (fs.hardfault) {
852 curthread->td_lwp->lwp_ru.ru_majflt++;
853 } else {
854 curthread->td_lwp->lwp_ru.ru_minflt++;
855 }
856 }
857
858 /*
859 * Unlock everything, and return the held page.
860 */
861 vm_page_wakeup(fs.m);
862 /*vm_object_deallocate(fs.first_object);*/
863 /*fs.first_object = NULL; */
864 *errorp = 0;
865
866 done:
867 if (fs.first_object)
868 vm_object_drop(fs.first_object);
869 done2:
870 lwkt_reltoken(&map->token);
871 return(fs.m);
872 }
873
874 /*
875 * Fault in the specified (object,offset), dirty the returned page as
876 * needed. If the requested fault_type cannot be done NULL and an
877 * error is returned.
878 *
879 * A held (but not busied) page is returned.
880 *
881 * The passed in object must be held as specified by the shared
882 * argument.
883 */
884 vm_page_t
885 vm_fault_object_page(vm_object_t object, vm_ooffset_t offset,
886 vm_prot_t fault_type, int fault_flags,
887 int *sharedp, int *errorp)
888 {
889 int result;
890 vm_pindex_t first_pindex;
891 struct faultstate fs;
892 struct vm_map_entry entry;
893
894 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
895 bzero(&entry, sizeof(entry));
896 entry.object.vm_object = object;
897 entry.maptype = VM_MAPTYPE_NORMAL;
898 entry.protection = entry.max_protection = fault_type;
899
900 fs.hardfault = 0;
901 fs.fault_flags = fault_flags;
902 fs.map = NULL;
903 fs.shared = vm_shared_fault;
904 fs.first_shared = *sharedp;
905 fs.vp = NULL;
906 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0);
907
908 /*
909 * Might require swap block adjustments
910 */
911 if (fs.first_shared && (fault_flags & (VM_FAULT_UNSWAP | VM_FAULT_DIRTY))) {
912 fs.first_shared = 0;
913 vm_object_upgrade(object);
914 }
915
916 /*
917 * Retry loop as needed (typically for shared->exclusive transitions)
918 */
919 RetryFault:
920 *sharedp = fs.first_shared;
921 first_pindex = OFF_TO_IDX(offset);
922 fs.first_object = object;
923 fs.entry = &entry;
924 fs.first_prot = fault_type;
925 fs.wired = 0;
926 /*fs.map_generation = 0; unused */
927
928 /*
929 * Make a reference to this object to prevent its disposal while we
930 * are messing with it. Once we have the reference, the map is free
931 * to be diddled. Since objects reference their shadows (and copies),
932 * they will stay around as well.
933 *
934 * The reference should also prevent an unexpected collapse of the
935 * parent that might move pages from the current object into the
936 * parent unexpectedly, resulting in corruption.
937 *
938 * Bump the paging-in-progress count to prevent size changes (e.g.
939 * truncation operations) during I/O. This must be done after
940 * obtaining the vnode lock in order to avoid possible deadlocks.
941 */
942 if (fs.vp == NULL)
943 fs.vp = vnode_pager_lock(fs.first_object);
944
945 fs.lookup_still_valid = TRUE;
946 fs.first_m = NULL;
947 fs.object = fs.first_object; /* so unlock_and_deallocate works */
948
949 #if 0
950 /* XXX future - ability to operate on VM object using vpagetable */
951 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) {
952 result = vm_fault_vpagetable(&fs, &first_pindex,
953 fs.entry->aux.master_pde,
954 fault_type, 0);
955 if (result == KERN_TRY_AGAIN) {
956 if (fs.first_shared == 0 && *sharedp)
957 vm_object_upgrade(object);
958 goto RetryFault;
959 }
960 if (result != KERN_SUCCESS) {
961 *errorp = result;
962 return (NULL);
963 }
964 }
965 #endif
966
967 /*
968 * Now we have the actual (object, pindex), fault in the page. If
969 * vm_fault_object() fails it will unlock and deallocate the FS
970 * data. If it succeeds everything remains locked and fs->object
971 * will have an additinal PIP count if it is not equal to
972 * fs->first_object
973 *
974 * On KERN_TRY_AGAIN vm_fault_object() leaves fs.first_object intact.
975 * We may have to upgrade its lock to handle the requested fault.
976 */
977 result = vm_fault_object(&fs, first_pindex, fault_type, 0);
978
979 if (result == KERN_TRY_AGAIN) {
980 if (fs.first_shared == 0 && *sharedp)
981 vm_object_upgrade(object);
982 goto RetryFault;
983 }
984 if (result != KERN_SUCCESS) {
985 *errorp = result;
986 return(NULL);
987 }
988
989 if ((fault_type & VM_PROT_WRITE) && (fs.prot & VM_PROT_WRITE) == 0) {
990 *errorp = KERN_PROTECTION_FAILURE;
991 unlock_and_deallocate(&fs);
992 return(NULL);
993 }
994
995 /*
996 * On success vm_fault_object() does not unlock or deallocate, so we
997 * do it here. Note that the returned fs.m will be busied.
998 */
999 unlock_things(&fs);
1000
1001 /*
1002 * Return a held page. We are not doing any pmap manipulation so do
1003 * not set PG_MAPPED. However, adjust the page flags according to
1004 * the fault type because the caller may not use a managed pmapping
1005 * (so we don't want to lose the fact that the page will be dirtied
1006 * if a write fault was specified).
1007 */
1008 vm_page_hold(fs.m);
1009 vm_page_activate(fs.m);
1010 if ((fault_type & VM_PROT_WRITE) || (fault_flags & VM_FAULT_DIRTY))
1011 vm_page_dirty(fs.m);
1012 if (fault_flags & VM_FAULT_UNSWAP)
1013 swap_pager_unswapped(fs.m);
1014
1015 /*
1016 * Indicate that the page was accessed.
1017 */
1018 vm_page_flag_set(fs.m, PG_REFERENCED);
1019
1020 if (curthread->td_lwp) {
1021 if (fs.hardfault) {
1022 curthread->td_lwp->lwp_ru.ru_majflt++;
1023 } else {
1024 curthread->td_lwp->lwp_ru.ru_minflt++;
1025 }
1026 }
1027
1028 /*
1029 * Unlock everything, and return the held page.
1030 */
1031 vm_page_wakeup(fs.m);
1032 /*vm_object_deallocate(fs.first_object);*/
1033 /*fs.first_object = NULL; */
1034
1035 *errorp = 0;
1036 return(fs.m);
1037 }
1038
1039 /*
1040 * Translate the virtual page number (first_pindex) that is relative
1041 * to the address space into a logical page number that is relative to the
1042 * backing object. Use the virtual page table pointed to by (vpte).
1043 *
1044 * This implements an N-level page table. Any level can terminate the
1045 * scan by setting VPTE_PS. A linear mapping is accomplished by setting
1046 * VPTE_PS in the master page directory entry set via mcontrol(MADV_SETMAP).
1047 */
1048 static
1049 int
1050 vm_fault_vpagetable(struct faultstate *fs, vm_pindex_t *pindex,
1051 vpte_t vpte, int fault_type, int allow_nofault)
1052 {
1053 struct lwbuf *lwb;
1054 struct lwbuf lwb_cache;
1055 int vshift = VPTE_FRAME_END - PAGE_SHIFT; /* index bits remaining */
1056 int result = KERN_SUCCESS;
1057 vpte_t *ptep;
1058
1059 ASSERT_LWKT_TOKEN_HELD(vm_object_token(fs->first_object));
1060 for (;;) {
1061 /*
1062 * We cannot proceed if the vpte is not valid, not readable
1063 * for a read fault, or not writable for a write fault.
1064 */
1065 if ((vpte & VPTE_V) == 0) {
1066 unlock_and_deallocate(fs);
1067 return (KERN_FAILURE);
1068 }
1069 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_RW) == 0) {
1070 unlock_and_deallocate(fs);
1071 return (KERN_FAILURE);
1072 }
1073 if ((vpte & VPTE_PS) || vshift == 0)
1074 break;
1075 KKASSERT(vshift >= VPTE_PAGE_BITS);
1076
1077 /*
1078 * Get the page table page. Nominally we only read the page
1079 * table, but since we are actively setting VPTE_M and VPTE_A,
1080 * tell vm_fault_object() that we are writing it.
1081 *
1082 * There is currently no real need to optimize this.
1083 */
1084 result = vm_fault_object(fs, (vpte & VPTE_FRAME) >> PAGE_SHIFT,
1085 VM_PROT_READ|VM_PROT_WRITE,
1086 allow_nofault);
1087 if (result != KERN_SUCCESS)
1088 return (result);
1089
1090 /*
1091 * Process the returned fs.m and look up the page table
1092 * entry in the page table page.
1093 */
1094 vshift -= VPTE_PAGE_BITS;
1095 lwb = lwbuf_alloc(fs->m, &lwb_cache);
1096 ptep = ((vpte_t *)lwbuf_kva(lwb) +
1097 ((*pindex >> vshift) & VPTE_PAGE_MASK));
1098 vpte = *ptep;
1099
1100 /*
1101 * Page table write-back. If the vpte is valid for the
1102 * requested operation, do a write-back to the page table.
1103 *
1104 * XXX VPTE_M is not set properly for page directory pages.
1105 * It doesn't get set in the page directory if the page table
1106 * is modified during a read access.
1107 */
1108 vm_page_activate(fs->m);
1109 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_V) &&
1110 (vpte & VPTE_RW)) {
1111 if ((vpte & (VPTE_M|VPTE_A)) != (VPTE_M|VPTE_A)) {
1112 atomic_set_long(ptep, VPTE_M | VPTE_A);
1113 vm_page_dirty(fs->m);
1114 }
1115 }
1116 if ((fault_type & VM_PROT_READ) && (vpte & VPTE_V)) {
1117 if ((vpte & VPTE_A) == 0) {
1118 atomic_set_long(ptep, VPTE_A);
1119 vm_page_dirty(fs->m);
1120 }
1121 }
1122 lwbuf_free(lwb);
1123 vm_page_flag_set(fs->m, PG_REFERENCED);
1124 vm_page_wakeup(fs->m);
1125 fs->m = NULL;
1126 cleanup_successful_fault(fs);
1127 }
1128 /*
1129 * Combine remaining address bits with the vpte.
1130 */
1131 /* JG how many bits from each? */
1132 *pindex = ((vpte & VPTE_FRAME) >> PAGE_SHIFT) +
1133 (*pindex & ((1L << vshift) - 1));
1134 return (KERN_SUCCESS);
1135 }
1136
1137
1138 /*
1139 * This is the core of the vm_fault code.
1140 *
1141 * Do all operations required to fault-in (fs.first_object, pindex). Run
1142 * through the shadow chain as necessary and do required COW or virtual
1143 * copy operations. The caller has already fully resolved the vm_map_entry
1144 * and, if appropriate, has created a copy-on-write layer. All we need to
1145 * do is iterate the object chain.
1146 *
1147 * On failure (fs) is unlocked and deallocated and the caller may return or
1148 * retry depending on the failure code. On success (fs) is NOT unlocked or
1149 * deallocated, fs.m will contained a resolved, busied page, and fs.object
1150 * will have an additional PIP count if it is not equal to fs.first_object.
1151 *
1152 * If locks based on fs->first_shared or fs->shared are insufficient,
1153 * clear the appropriate field(s) and return RETRY. COWs require that
1154 * first_shared be 0, while page allocations (or frees) require that
1155 * shared be 0. Renames require that both be 0.
1156 *
1157 * fs->first_object must be held on call.
1158 */
1159 static
1160 int
1161 vm_fault_object(struct faultstate *fs, vm_pindex_t first_pindex,
1162 vm_prot_t fault_type, int allow_nofault)
1163 {
1164 vm_object_t next_object;
1165 vm_pindex_t pindex;
1166 int error;
1167
1168 ASSERT_LWKT_TOKEN_HELD(vm_object_token(fs->first_object));
1169 fs->prot = fs->first_prot;
1170 fs->object = fs->first_object;
1171 pindex = first_pindex;
1172
1173 vm_object_chain_acquire(fs->first_object, fs->shared);
1174 vm_object_pip_add(fs->first_object, 1);
1175
1176 /*
1177 * If a read fault occurs we try to make the page writable if
1178 * possible. There are three cases where we cannot make the
1179 * page mapping writable:
1180 *
1181 * (1) The mapping is read-only or the VM object is read-only,
1182 * fs->prot above will simply not have VM_PROT_WRITE set.
1183 *
1184 * (2) If the mapping is a virtual page table we need to be able
1185 * to detect writes so we can set VPTE_M in the virtual page
1186 * table.
1187 *
1188 * (3) If the VM page is read-only or copy-on-write, upgrading would
1189 * just result in an unnecessary COW fault.
1190 *
1191 * VM_PROT_VPAGED is set if faulting via a virtual page table and
1192 * causes adjustments to the 'M'odify bit to also turn off write
1193 * access to force a re-fault.
1194 */
1195 if (fs->entry->maptype == VM_MAPTYPE_VPAGETABLE) {
1196 if ((fault_type & VM_PROT_WRITE) == 0)
1197 fs->prot &= ~VM_PROT_WRITE;
1198 }
1199
1200 if (curthread->td_lwp && curthread->td_lwp->lwp_vmspace &&
1201 pmap_emulate_ad_bits(&curthread->td_lwp->lwp_vmspace->vm_pmap)) {
1202 if ((fault_type & VM_PROT_WRITE) == 0)
1203 fs->prot &= ~VM_PROT_WRITE;
1204 }
1205
1206 /* vm_object_hold(fs->object); implied b/c object == first_object */
1207
1208 for (;;) {
1209 /*
1210 * The entire backing chain from first_object to object
1211 * inclusive is chainlocked.
1212 *
1213 * If the object is dead, we stop here
1214 */
1215 if (fs->object->flags & OBJ_DEAD) {
1216 vm_object_pip_wakeup(fs->first_object);
1217 vm_object_chain_release_all(fs->first_object,
1218 fs->object);
1219 if (fs->object != fs->first_object)
1220 vm_object_drop(fs->object);
1221 unlock_and_deallocate(fs);
1222 return (KERN_PROTECTION_FAILURE);
1223 }
1224
1225 /*
1226 * See if the page is resident. Wait/Retry if the page is
1227 * busy (lots of stuff may have changed so we can't continue
1228 * in that case).
1229 *
1230 * We can theoretically allow the soft-busy case on a read
1231 * fault if the page is marked valid, but since such
1232 * pages are typically already pmap'd, putting that
1233 * special case in might be more effort then it is
1234 * worth. We cannot under any circumstances mess
1235 * around with a vm_page_t->busy page except, perhaps,
1236 * to pmap it.
1237 */
1238 fs->m = vm_page_lookup_busy_try(fs->object, pindex,
1239 TRUE, &error);
1240 if (error) {
1241 vm_object_pip_wakeup(fs->first_object);
1242 vm_object_chain_release_all(fs->first_object,
1243 fs->object);
1244 if (fs->object != fs->first_object)
1245 vm_object_drop(fs->object);
1246 unlock_things(fs);
1247 vm_page_sleep_busy(fs->m, TRUE, "vmpfw");
1248 mycpu->gd_cnt.v_intrans++;
1249 /*vm_object_deallocate(fs->first_object);*/
1250 /*fs->first_object = NULL;*/
1251 fs->m = NULL;
1252 return (KERN_TRY_AGAIN);
1253 }
1254 if (fs->m) {
1255 /*
1256 * The page is busied for us.
1257 *
1258 * If reactivating a page from PQ_CACHE we may have
1259 * to rate-limit.
1260 */
1261 int queue = fs->m->queue;
1262 vm_page_unqueue_nowakeup(fs->m);
1263
1264 if ((queue - fs->m->pc) == PQ_CACHE &&
1265 vm_page_count_severe()) {
1266 vm_page_activate(fs->m);
1267 vm_page_wakeup(fs->m);
1268 fs->m = NULL;
1269 vm_object_pip_wakeup(fs->first_object);
1270 vm_object_chain_release_all(fs->first_object,
1271 fs->object);
1272 if (fs->object != fs->first_object)
1273 vm_object_drop(fs->object);
1274 unlock_and_deallocate(fs);
1275 if (allow_nofault == 0 ||
1276 (curthread->td_flags & TDF_NOFAULT) == 0) {
1277 vm_wait_pfault();
1278 }
1279 return (KERN_TRY_AGAIN);
1280 }
1281
1282 /*
1283 * If it still isn't completely valid (readable),
1284 * or if a read-ahead-mark is set on the VM page,
1285 * jump to readrest, else we found the page and
1286 * can return.
1287 *
1288 * We can release the spl once we have marked the
1289 * page busy.
1290 */
1291 if (fs->m->object != &kernel_object) {
1292 if ((fs->m->valid & VM_PAGE_BITS_ALL) !=
1293 VM_PAGE_BITS_ALL) {
1294 goto readrest;
1295 }
1296 if (fs->m->flags & PG_RAM) {
1297 if (debug_cluster)
1298 kprintf("R");
1299 vm_page_flag_clear(fs->m, PG_RAM);
1300 goto readrest;
1301 }
1302 }
1303 break; /* break to PAGE HAS BEEN FOUND */
1304 }
1305
1306 /*
1307 * Page is not resident, If this is the search termination
1308 * or the pager might contain the page, allocate a new page.
1309 */
1310 if (TRYPAGER(fs) || fs->object == fs->first_object) {
1311 /*
1312 * Allocating, must be exclusive.
1313 */
1314 if (fs->object == fs->first_object &&
1315 fs->first_shared) {
1316 fs->first_shared = 0;
1317 vm_object_pip_wakeup(fs->first_object);
1318 vm_object_chain_release_all(fs->first_object,
1319 fs->object);
1320 if (fs->object != fs->first_object)
1321 vm_object_drop(fs->object);
1322 unlock_and_deallocate(fs);
1323 return (KERN_TRY_AGAIN);
1324 }
1325 if (fs->object != fs->first_object &&
1326 fs->shared) {
1327 fs->first_shared = 0;
1328 fs->shared = 0;
1329 vm_object_pip_wakeup(fs->first_object);
1330 vm_object_chain_release_all(fs->first_object,
1331 fs->object);
1332 if (fs->object != fs->first_object)
1333 vm_object_drop(fs->object);
1334 unlock_and_deallocate(fs);
1335 return (KERN_TRY_AGAIN);
1336 }
1337
1338 /*
1339 * If the page is beyond the object size we fail
1340 */
1341 if (pindex >= fs->object->size) {
1342 vm_object_pip_wakeup(fs->first_object);
1343 vm_object_chain_release_all(fs->first_object,
1344 fs->object);
1345 if (fs->object != fs->first_object)
1346 vm_object_drop(fs->object);
1347 unlock_and_deallocate(fs);
1348 return (KERN_PROTECTION_FAILURE);
1349 }
1350
1351 /*
1352 * Allocate a new page for this object/offset pair.
1353 *
1354 * It is possible for the allocation to race, so
1355 * handle the case.
1356 */
1357 fs->m = NULL;
1358 if (!vm_page_count_severe()) {
1359 fs->m = vm_page_alloc(fs->object, pindex,
1360 ((fs->vp || fs->object->backing_object) ?
1361 VM_ALLOC_NULL_OK | VM_ALLOC_NORMAL :
1362 VM_ALLOC_NULL_OK | VM_ALLOC_NORMAL |
1363 VM_ALLOC_USE_GD | VM_ALLOC_ZERO));
1364 }
1365 if (fs->m == NULL) {
1366 vm_object_pip_wakeup(fs->first_object);
1367 vm_object_chain_release_all(fs->first_object,
1368 fs->object);
1369 if (fs->object != fs->first_object)
1370 vm_object_drop(fs->object);
1371 unlock_and_deallocate(fs);
1372 if (allow_nofault == 0 ||
1373 (curthread->td_flags & TDF_NOFAULT) == 0) {
1374 vm_wait_pfault();
1375 }
1376 return (KERN_TRY_AGAIN);
1377 }
1378
1379 /*
1380 * Fall through to readrest. We have a new page which
1381 * will have to be paged (since m->valid will be 0).
1382 */
1383 }
1384
1385 readrest:
1386 /*
1387 * We have found an invalid or partially valid page, a
1388 * page with a read-ahead mark which might be partially or
1389 * fully valid (and maybe dirty too), or we have allocated
1390 * a new page.
1391 *
1392 * Attempt to fault-in the page if there is a chance that the
1393 * pager has it, and potentially fault in additional pages
1394 * at the same time.
1395 *
1396 * If TRYPAGER is true then fs.m will be non-NULL and busied
1397 * for us.
1398 */
1399 if (TRYPAGER(fs)) {
1400 int rv;
1401 int seqaccess;
1402 u_char behavior = vm_map_entry_behavior(fs->entry);
1403
1404 if (behavior == MAP_ENTRY_BEHAV_RANDOM)
1405 seqaccess = 0;
1406 else
1407 seqaccess = -1;
1408
1409 /*
1410 * Doing I/O may synchronously insert additional
1411 * pages so we can't be shared at this point either.
1412 *
1413 * NOTE: We can't free fs->m here in the allocated
1414 * case (fs->object != fs->first_object) as
1415 * this would require an exclusively locked
1416 * VM object.
1417 */
1418 if (fs->object == fs->first_object &&
1419 fs->first_shared) {
1420 vm_page_deactivate(fs->m);
1421 vm_page_wakeup(fs->m);
1422 fs->m = NULL;
1423 fs->first_shared = 0;
1424 vm_object_pip_wakeup(fs->first_object);
1425 vm_object_chain_release_all(fs->first_object,
1426 fs->object);
1427 if (fs->object != fs->first_object)
1428 vm_object_drop(fs->object);
1429 unlock_and_deallocate(fs);
1430 return (KERN_TRY_AGAIN);
1431 }
1432 if (fs->object != fs->first_object &&
1433 fs->shared) {
1434 vm_page_deactivate(fs->m);
1435 vm_page_wakeup(fs->m);
1436 fs->m = NULL;
1437 fs->first_shared = 0;
1438 fs->shared = 0;
1439 vm_object_pip_wakeup(fs->first_object);
1440 vm_object_chain_release_all(fs->first_object,
1441 fs->object);
1442 if (fs->object != fs->first_object)
1443 vm_object_drop(fs->object);
1444 unlock_and_deallocate(fs);
1445 return (KERN_TRY_AGAIN);
1446 }
1447
1448 /*
1449 * Avoid deadlocking against the map when doing I/O.
1450 * fs.object and the page is PG_BUSY'd.
1451 *
1452 * NOTE: Once unlocked, fs->entry can become stale
1453 * so this will NULL it out.
1454 *
1455 * NOTE: fs->entry is invalid until we relock the
1456 * map and verify that the timestamp has not
1457 * changed.
1458 */
1459 unlock_map(fs);
1460
1461 /*
1462 * Acquire the page data. We still hold a ref on
1463 * fs.object and the page has been PG_BUSY's.
1464 *
1465 * The pager may replace the page (for example, in
1466 * order to enter a fictitious page into the
1467 * object). If it does so it is responsible for
1468 * cleaning up the passed page and properly setting
1469 * the new page PG_BUSY.
1470 *
1471 * If we got here through a PG_RAM read-ahead
1472 * mark the page may be partially dirty and thus
1473 * not freeable. Don't bother checking to see
1474 * if the pager has the page because we can't free
1475 * it anyway. We have to depend on the get_page
1476 * operation filling in any gaps whether there is
1477 * backing store or not.
1478 */
1479 rv = vm_pager_get_page(fs->object, &fs->m, seqaccess);
1480
1481 if (rv == VM_PAGER_OK) {
1482 /*
1483 * Relookup in case pager changed page. Pager
1484 * is responsible for disposition of old page
1485 * if moved.
1486 *
1487 * XXX other code segments do relookups too.
1488 * It's a bad abstraction that needs to be
1489 * fixed/removed.
1490 */
1491 fs->m = vm_page_lookup(fs->object, pindex);
1492 if (fs->m == NULL) {
1493 vm_object_pip_wakeup(fs->first_object);
1494 vm_object_chain_release_all(
1495 fs->first_object, fs->object);
1496 if (fs->object != fs->first_object)
1497 vm_object_drop(fs->object);
1498 unlock_and_deallocate(fs);
1499 return (KERN_TRY_AGAIN);
1500 }
1501 ++fs->hardfault;
1502 break; /* break to PAGE HAS BEEN FOUND */
1503 }
1504
1505 /*
1506 * Remove the bogus page (which does not exist at this
1507 * object/offset); before doing so, we must get back
1508 * our object lock to preserve our invariant.
1509 *
1510 * Also wake up any other process that may want to bring
1511 * in this page.
1512 *
1513 * If this is the top-level object, we must leave the
1514 * busy page to prevent another process from rushing
1515 * past us, and inserting the page in that object at
1516 * the same time that we are.
1517 */
1518 if (rv == VM_PAGER_ERROR) {
1519 if (curproc) {
1520 kprintf("vm_fault: pager read error, "
1521 "pid %d (%s)\n",
1522 curproc->p_pid,
1523 curproc->p_comm);
1524 } else {
1525 kprintf("vm_fault: pager read error, "
1526 "thread %p (%s)\n",
1527 curthread,
1528 curproc->p_comm);
1529 }
1530 }
1531
1532 /*
1533 * Data outside the range of the pager or an I/O error
1534 *
1535 * The page may have been wired during the pagein,
1536 * e.g. by the buffer cache, and cannot simply be
1537 * freed. Call vnode_pager_freepage() to deal with it.
1538 *
1539 * Also note that we cannot free the page if we are
1540 * holding the related object shared. XXX not sure
1541 * what to do in that case.
1542 */
1543 if (fs->object != fs->first_object) {
1544 vnode_pager_freepage(fs->m);
1545 fs->m = NULL;
1546 /*
1547 * XXX - we cannot just fall out at this
1548 * point, m has been freed and is invalid!
1549 */
1550 }
1551 /*
1552 * XXX - the check for kernel_map is a kludge to work
1553 * around having the machine panic on a kernel space
1554 * fault w/ I/O error.
1555 */
1556 if (((fs->map != &kernel_map) &&
1557 (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) {
1558 if (fs->m) {
1559 if (fs->first_shared) {
1560 vm_page_deactivate(fs->m);
1561 vm_page_wakeup(fs->m);
1562 } else {
1563 vnode_pager_freepage(fs->m);
1564 }
1565 fs->m = NULL;
1566 }
1567 vm_object_pip_wakeup(fs->first_object);
1568 vm_object_chain_release_all(fs->first_object,
1569 fs->object);
1570 if (fs->object != fs->first_object)
1571 vm_object_drop(fs->object);
1572 unlock_and_deallocate(fs);
1573 if (rv == VM_PAGER_ERROR)
1574 return (KERN_FAILURE);
1575 else
1576 return (KERN_PROTECTION_FAILURE);
1577 /* NOT REACHED */
1578 }
1579 }
1580
1581 /*
1582 * We get here if the object has a default pager (or unwiring)
1583 * or the pager doesn't have the page.
1584 *
1585 * fs->first_m will be used for the COW unless we find a
1586 * deeper page to be mapped read-only, in which case the
1587 * unlock*(fs) will free first_m.
1588 */
1589 if (fs->object == fs->first_object)
1590 fs->first_m = fs->m;
1591
1592 /*
1593 * Move on to the next object. The chain lock should prevent
1594 * the backing_object from getting ripped out from under us.
1595 *
1596 * The object lock for the next object is governed by
1597 * fs->shared.
1598 */
1599 if ((next_object = fs->object->backing_object) != NULL) {
1600 if (fs->shared)
1601 vm_object_hold_shared(next_object);
1602 else
1603 vm_object_hold(next_object);
1604 vm_object_chain_acquire(next_object, fs->shared);
1605 KKASSERT(next_object == fs->object->backing_object);
1606 pindex += OFF_TO_IDX(fs->object->backing_object_offset);
1607 }
1608
1609 if (next_object == NULL) {
1610 /*
1611 * If there's no object left, fill the page in the top
1612 * object with zeros.
1613 */
1614 if (fs->object != fs->first_object) {
1615 #if 0
1616 if (fs->first_object->backing_object !=
1617 fs->object) {
1618 vm_object_hold(fs->first_object->backing_object);
1619 }
1620 #endif
1621 vm_object_chain_release_all(
1622 fs->first_object->backing_object,
1623 fs->object);
1624 #if 0
1625 if (fs->first_object->backing_object !=
1626 fs->object) {
1627 vm_object_drop(fs->first_object->backing_object);
1628 }
1629 #endif
1630 vm_object_pip_wakeup(fs->object);
1631 vm_object_drop(fs->object);
1632 fs->object = fs->first_object;
1633 pindex = first_pindex;
1634 fs->m = fs->first_m;
1635 }
1636 fs->first_m = NULL;
1637
1638 /*
1639 * Zero the page if necessary and mark it valid.
1640 */
1641 if ((fs->m->flags & PG_ZERO) == 0) {
1642 vm_page_zero_fill(fs->m);
1643 } else {
1644 #ifdef PMAP_DEBUG
1645 pmap_page_assertzero(VM_PAGE_TO_PHYS(fs->m));
1646 #endif
1647 vm_page_flag_clear(fs->m, PG_ZERO);
1648 mycpu->gd_cnt.v_ozfod++;
1649 }
1650 mycpu->gd_cnt.v_zfod++;
1651 fs->m->valid = VM_PAGE_BITS_ALL;
1652 break; /* break to PAGE HAS BEEN FOUND */
1653 }
1654 if (fs->object != fs->first_object) {
1655 vm_object_pip_wakeup(fs->object);
1656 vm_object_lock_swap();
1657 vm_object_drop(fs->object);
1658 }
1659 KASSERT(fs->object != next_object,
1660 ("object loop %p", next_object));
1661 fs->object = next_object;
1662 vm_object_pip_add(fs->object, 1);
1663 }
1664
1665 /*
1666 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock
1667 * is held.]
1668 *
1669 * object still held.
1670 *
1671 * local shared variable may be different from fs->shared.
1672 *
1673 * If the page is being written, but isn't already owned by the
1674 * top-level object, we have to copy it into a new page owned by the
1675 * top-level object.
1676 */
1677 KASSERT((fs->m->flags & PG_BUSY) != 0,
1678 ("vm_fault: not busy after main loop"));
1679
1680 if (fs->object != fs->first_object) {
1681 /*
1682 * We only really need to copy if we want to write it.
1683 */
1684 if (fault_type & VM_PROT_WRITE) {
1685 /*
1686 * This allows pages to be virtually copied from a
1687 * backing_object into the first_object, where the
1688 * backing object has no other refs to it, and cannot
1689 * gain any more refs. Instead of a bcopy, we just
1690 * move the page from the backing object to the
1691 * first object. Note that we must mark the page
1692 * dirty in the first object so that it will go out
1693 * to swap when needed.
1694 */
1695 if (
1696 /*
1697 * Must be holding exclusive locks
1698 */
1699 fs->first_shared == 0 &&
1700 fs->shared == 0 &&
1701 /*
1702 * Map, if present, has not changed
1703 */
1704 (fs->map == NULL ||
1705 fs->map_generation == fs->map->timestamp) &&
1706 /*
1707 * Only one shadow object
1708 */
1709 (fs->object->shadow_count == 1) &&
1710 /*
1711 * No COW refs, except us
1712 */
1713 (fs->object->ref_count == 1) &&
1714 /*
1715 * No one else can look this object up
1716 */
1717 (fs->object->handle == NULL) &&
1718 /*
1719 * No other ways to look the object up
1720 */
1721 ((fs->object->type == OBJT_DEFAULT) ||
1722 (fs->object->type == OBJT_SWAP)) &&
1723 /*
1724 * We don't chase down the shadow chain
1725 */
1726 (fs->object == fs->first_object->backing_object) &&
1727
1728 /*
1729 * grab the lock if we need to
1730 */
1731 (fs->lookup_still_valid ||
1732 fs->map == NULL ||
1733 lockmgr(&fs->map->lock, LK_EXCLUSIVE|LK_NOWAIT) == 0)
1734 ) {
1735 /*
1736 * (first_m) and (m) are both busied. We have
1737 * move (m) into (first_m)'s object/pindex
1738 * in an atomic fashion, then free (first_m).
1739 *
1740 * first_object is held so second remove
1741 * followed by the rename should wind
1742 * up being atomic. vm_page_free() might
1743 * block so we don't do it until after the
1744 * rename.
1745 */
1746 fs->lookup_still_valid = 1;
1747 vm_page_protect(fs->first_m, VM_PROT_NONE);
1748 vm_page_remove(fs->first_m);
1749 vm_page_rename(fs->m, fs->first_object,
1750 first_pindex);
1751 vm_page_free(fs->first_m);
1752 fs->first_m = fs->m;
1753 fs->m = NULL;
1754 mycpu->gd_cnt.v_cow_optim++;
1755 } else {
1756 /*
1757 * Oh, well, lets copy it.
1758 *
1759 * Why are we unmapping the original page
1760 * here? Well, in short, not all accessors
1761 * of user memory go through the pmap. The
1762 * procfs code doesn't have access user memory
1763 * via a local pmap, so vm_fault_page*()
1764 * can't call pmap_enter(). And the umtx*()
1765 * code may modify the COW'd page via a DMAP
1766 * or kernel mapping and not via the pmap,
1767 * leaving the original page still mapped
1768 * read-only into the pmap.
1769 *
1770 * So we have to remove the page from at
1771 * least the current pmap if it is in it.
1772 * Just remove it from all pmaps.
1773 */
1774 KKASSERT(fs->first_shared == 0);
1775 vm_page_copy(fs->m, fs->first_m);
1776 vm_page_protect(fs->m, VM_PROT_NONE);
1777 vm_page_event(fs->m, VMEVENT_COW);
1778 }
1779
1780 /*
1781 * We no longer need the old page or object.
1782 */
1783 if (fs->m)
1784 release_page(fs);
1785
1786 /*
1787 * We intend to revert to first_object, undo the
1788 * chain lock through to that.
1789 */
1790 #if 0
1791 if (fs->first_object->backing_object != fs->object)
1792 vm_object_hold(fs->first_object->backing_object);
1793 #endif
1794 vm_object_chain_release_all(
1795 fs->first_object->backing_object,
1796 fs->object);
1797 #if 0
1798 if (fs->first_object->backing_object != fs->object)
1799 vm_object_drop(fs->first_object->backing_object);
1800 #endif
1801
1802 /*
1803 * fs->object != fs->first_object due to above
1804 * conditional
1805 */
1806 vm_object_pip_wakeup(fs->object);
1807 vm_object_drop(fs->object);
1808
1809 /*
1810 * Only use the new page below...
1811 */
1812 mycpu->gd_cnt.v_cow_faults++;
1813 fs->m = fs->first_m;
1814 fs->object = fs->first_object;
1815 pindex = first_pindex;
1816 } else {
1817 /*
1818 * If it wasn't a write fault avoid having to copy
1819 * the page by mapping it read-only.
1820 */
1821 fs->prot &= ~VM_PROT_WRITE;
1822 }
1823 }
1824
1825 /*
1826 * Relock the map if necessary, then check the generation count.
1827 * relock_map() will update fs->timestamp to account for the
1828 * relocking if necessary.
1829 *
1830 * If the count has changed after relocking then all sorts of
1831 * crap may have happened and we have to retry.
1832 *
1833 * NOTE: The relock_map() can fail due to a deadlock against
1834 * the vm_page we are holding BUSY.
1835 */
1836 if (fs->lookup_still_valid == FALSE && fs->map) {
1837 if (relock_map(fs) ||
1838 fs->map->timestamp != fs->map_generation) {
1839 release_page(fs);
1840 vm_object_pip_wakeup(fs->first_object);
1841 vm_object_chain_release_all(fs->first_object,
1842 fs->object);
1843 if (fs->object != fs->first_object)
1844 vm_object_drop(fs->object);
1845 unlock_and_deallocate(fs);
1846 return (KERN_TRY_AGAIN);
1847 }
1848 }
1849
1850 /*
1851 * If the fault is a write, we know that this page is being
1852 * written NOW so dirty it explicitly to save on pmap_is_modified()
1853 * calls later.
1854 *
1855 * If this is a NOSYNC mmap we do not want to set PG_NOSYNC
1856 * if the page is already dirty to prevent data written with
1857 * the expectation of being synced from not being synced.
1858 * Likewise if this entry does not request NOSYNC then make
1859 * sure the page isn't marked NOSYNC. Applications sharing
1860 * data should use the same flags to avoid ping ponging.
1861 *
1862 * Also tell the backing pager, if any, that it should remove
1863 * any swap backing since the page is now dirty.
1864 */
1865 vm_page_activate(fs->m);
1866 if (fs->prot & VM_PROT_WRITE) {
1867 vm_object_set_writeable_dirty(fs->m->object);
1868 vm_set_nosync(fs->m, fs->entry);
1869 if (fs->fault_flags & VM_FAULT_DIRTY) {
1870 vm_page_dirty(fs->m);
1871 swap_pager_unswapped(fs->m);
1872 }
1873 }
1874
1875 vm_object_pip_wakeup(fs->first_object);
1876 vm_object_chain_release_all(fs->first_object, fs->object);
1877 if (fs->object != fs->first_object)
1878 vm_object_drop(fs->object);
1879
1880 /*
1881 * Page had better still be busy. We are still locked up and
1882 * fs->object will have another PIP reference if it is not equal
1883 * to fs->first_object.
1884 */
1885 KASSERT(fs->m->flags & PG_BUSY,
1886 ("vm_fault: page %p not busy!", fs->m));
1887
1888 /*
1889 * Sanity check: page must be completely valid or it is not fit to
1890 * map into user space. vm_pager_get_pages() ensures this.
1891 */
1892 if (fs->m->valid != VM_PAGE_BITS_ALL) {
1893 vm_page_zero_invalid(fs->m, TRUE);
1894 kprintf("Warning: page %p partially invalid on fault\n", fs->m);
1895 }
1896 vm_page_flag_clear(fs->m, PG_ZERO);
1897
1898 return (KERN_SUCCESS);
1899 }
1900
1901 /*
1902 * Hold each of the physical pages that are mapped by the specified range of
1903 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid
1904 * and allow the specified types of access, "prot". If all of the implied
1905 * pages are successfully held, then the number of held pages is returned
1906 * together with pointers to those pages in the array "ma". However, if any
1907 * of the pages cannot be held, -1 is returned.
1908 */
1909 int
1910 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len,
1911 vm_prot_t prot, vm_page_t *ma, int max_count)
1912 {
1913 vm_offset_t start, end;
1914 int i, npages, error;
1915
1916 start = trunc_page(addr);
1917 end = round_page(addr + len);
1918
1919 npages = howmany(end - start, PAGE_SIZE);
1920
1921 if (npages > max_count)
1922 return -1;
1923
1924 for (i = 0; i < npages; i++) {
1925 // XXX error handling
1926 ma[i] = vm_fault_page_quick(start + (i * PAGE_SIZE),
1927 prot,
1928 &error);
1929 }
1930
1931 return npages;
1932 }
1933
1934 /*
1935 * Wire down a range of virtual addresses in a map. The entry in question
1936 * should be marked in-transition and the map must be locked. We must
1937 * release the map temporarily while faulting-in the page to avoid a
1938 * deadlock. Note that the entry may be clipped while we are blocked but
1939 * will never be freed.
1940 *
1941 * No requirements.
1942 */
1943 int
1944 vm_fault_wire(vm_map_t map, vm_map_entry_t entry, boolean_t user_wire)
1945 {
1946 boolean_t fictitious;
1947 vm_offset_t start;
1948 vm_offset_t end;
1949 vm_offset_t va;
1950 vm_paddr_t pa;
1951 vm_page_t m;
1952 pmap_t pmap;
1953 int rv;
1954
1955 lwkt_gettoken(&map->token);
1956
1957 pmap = vm_map_pmap(map);
1958 start = entry->start;
1959 end = entry->end;
1960 fictitious = entry->object.vm_object &&
1961 ((entry->object.vm_object->type == OBJT_DEVICE) ||
1962 (entry->object.vm_object->type == OBJT_MGTDEVICE));
1963 if (entry->eflags & MAP_ENTRY_KSTACK)
1964 start += PAGE_SIZE;
1965 map->timestamp++;
1966 vm_map_unlock(map);
1967
1968 /*
1969 * We simulate a fault to get the page and enter it in the physical
1970 * map.
1971 */
1972 for (va = start; va < end; va += PAGE_SIZE) {
1973 if (user_wire) {
1974 rv = vm_fault(map, va, VM_PROT_READ,
1975 VM_FAULT_USER_WIRE);
1976 } else {
1977 rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE,
1978 VM_FAULT_CHANGE_WIRING);
1979 }
1980 if (rv) {
1981 while (va > start) {
1982 va -= PAGE_SIZE;
1983 if ((pa = pmap_extract(pmap, va)) == 0)
1984 continue;
1985 pmap_change_wiring(pmap, va, FALSE, entry);
1986 if (!fictitious) {
1987 m = PHYS_TO_VM_PAGE(pa);
1988 vm_page_busy_wait(m, FALSE, "vmwrpg");
1989 vm_page_unwire(m, 1);
1990 vm_page_wakeup(m);
1991 }
1992 }
1993 goto done;
1994 }
1995 }
1996 rv = KERN_SUCCESS;
1997 done:
1998 vm_map_lock(map);
1999 lwkt_reltoken(&map->token);
2000 return (rv);
2001 }
2002
2003 /*
2004 * Unwire a range of virtual addresses in a map. The map should be
2005 * locked.
2006 */
2007 void
2008 vm_fault_unwire(vm_map_t map, vm_map_entry_t entry)
2009 {
2010 boolean_t fictitious;
2011 vm_offset_t start;
2012 vm_offset_t end;
2013 vm_offset_t va;
2014 vm_paddr_t pa;
2015 vm_page_t m;
2016 pmap_t pmap;
2017
2018 lwkt_gettoken(&map->token);
2019
2020 pmap = vm_map_pmap(map);
2021 start = entry->start;
2022 end = entry->end;
2023 fictitious = entry->object.vm_object &&
2024 ((entry->object.vm_object->type == OBJT_DEVICE) ||
2025 (entry->object.vm_object->type == OBJT_MGTDEVICE));
2026 if (entry->eflags & MAP_ENTRY_KSTACK)
2027 start += PAGE_SIZE;
2028
2029 /*
2030 * Since the pages are wired down, we must be able to get their
2031 * mappings from the physical map system.
2032 */
2033 for (va = start; va < end; va += PAGE_SIZE) {
2034 pa = pmap_extract(pmap, va);
2035 if (pa != 0) {
2036 pmap_change_wiring(pmap, va, FALSE, entry);
2037 if (!fictitious) {
2038 m = PHYS_TO_VM_PAGE(pa);
2039 vm_page_busy_wait(m, FALSE, "vmwupg");
2040 vm_page_unwire(m, 1);
2041 vm_page_wakeup(m);
2042 }
2043 }
2044 }
2045 lwkt_reltoken(&map->token);
2046 }
2047
2048 /*
2049 * Copy all of the pages from a wired-down map entry to another.
2050 *
2051 * The source and destination maps must be locked for write.
2052 * The source and destination maps token must be held
2053 * The source map entry must be wired down (or be a sharing map
2054 * entry corresponding to a main map entry that is wired down).
2055 *
2056 * No other requirements.
2057 *
2058 * XXX do segment optimization
2059 */
2060 void
2061 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map,
2062 vm_map_entry_t dst_entry, vm_map_entry_t src_entry)
2063 {
2064 vm_object_t dst_object;
2065 vm_object_t src_object;
2066 vm_ooffset_t dst_offset;
2067 vm_ooffset_t src_offset;
2068 vm_prot_t prot;
2069 vm_offset_t vaddr;
2070 vm_page_t dst_m;
2071 vm_page_t src_m;
2072
2073 src_object = src_entry->object.vm_object;
2074 src_offset = src_entry->offset;
2075
2076 /*
2077 * Create the top-level object for the destination entry. (Doesn't
2078 * actually shadow anything - we copy the pages directly.)
2079 */
2080 vm_map_entry_allocate_object(dst_entry);
2081 dst_object = dst_entry->object.vm_object;
2082
2083 prot = dst_entry->max_protection;
2084
2085 /*
2086 * Loop through all of the pages in the entry's range, copying each
2087 * one from the source object (it should be there) to the destination
2088 * object.
2089 */
2090 vm_object_hold(src_object);
2091 vm_object_hold(dst_object);
2092 for (vaddr = dst_entry->start, dst_offset = 0;
2093 vaddr < dst_entry->end;
2094 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) {
2095
2096 /*
2097 * Allocate a page in the destination object
2098 */
2099 do {
2100 dst_m = vm_page_alloc(dst_object,
2101 OFF_TO_IDX(dst_offset),
2102 VM_ALLOC_NORMAL);
2103 if (dst_m == NULL) {
2104 vm_wait(0);
2105 }
2106 } while (dst_m == NULL);
2107
2108 /*
2109 * Find the page in the source object, and copy it in.
2110 * (Because the source is wired down, the page will be in
2111 * memory.)
2112 */
2113 src_m = vm_page_lookup(src_object,
2114 OFF_TO_IDX(dst_offset + src_offset));
2115 if (src_m == NULL)
2116 panic("vm_fault_copy_wired: page missing");
2117
2118 vm_page_copy(src_m, dst_m);
2119 vm_page_event(src_m, VMEVENT_COW);
2120
2121 /*
2122 * Enter it in the pmap...
2123 */
2124
2125 vm_page_flag_clear(dst_m, PG_ZERO);
2126 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE, dst_entry);
2127
2128 /*
2129 * Mark it no longer busy, and put it on the active list.
2130 */
2131 vm_page_activate(dst_m);
2132 vm_page_wakeup(dst_m);
2133 }
2134 vm_object_drop(dst_object);
2135 vm_object_drop(src_object);
2136 }
2137
2138 #if 0
2139
2140 /*
2141 * This routine checks around the requested page for other pages that
2142 * might be able to be faulted in. This routine brackets the viable
2143 * pages for the pages to be paged in.
2144 *
2145 * Inputs:
2146 * m, rbehind, rahead
2147 *
2148 * Outputs:
2149 * marray (array of vm_page_t), reqpage (index of requested page)
2150 *
2151 * Return value:
2152 * number of pages in marray
2153 */
2154 static int
2155 vm_fault_additional_pages(vm_page_t m, int rbehind, int rahead,
2156 vm_page_t *marray, int *reqpage)
2157 {
2158 int i,j;
2159 vm_object_t object;
2160 vm_pindex_t pindex, startpindex, endpindex, tpindex;
2161 vm_page_t rtm;
2162 int cbehind, cahead;
2163
2164 object = m->object;
2165 pindex = m->pindex;
2166
2167 /*
2168 * we don't fault-ahead for device pager
2169 */
2170 if ((object->type == OBJT_DEVICE) ||
2171 (object->type == OBJT_MGTDEVICE)) {
2172 *reqpage = 0;
2173 marray[0] = m;
2174 return 1;
2175 }
2176
2177 /*
2178 * if the requested page is not available, then give up now
2179 */
2180 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) {
2181 *reqpage = 0; /* not used by caller, fix compiler warn */
2182 return 0;
2183 }
2184
2185 if ((cbehind == 0) && (cahead == 0)) {
2186 *reqpage = 0;
2187 marray[0] = m;
2188 return 1;
2189 }
2190
2191 if (rahead > cahead) {
2192 rahead = cahead;
2193 }
2194
2195 if (rbehind > cbehind) {
2196 rbehind = cbehind;
2197 }
2198
2199 /*
2200 * Do not do any readahead if we have insufficient free memory.
2201 *
2202 * XXX code was broken disabled before and has instability
2203 * with this conditonal fixed, so shortcut for now.
2204 */
2205 if (burst_fault == 0 || vm_page_count_severe()) {
2206 marray[0] = m;
2207 *reqpage = 0;
2208 return 1;
2209 }
2210
2211 /*
2212 * scan backward for the read behind pages -- in memory
2213 *
2214 * Assume that if the page is not found an interrupt will not
2215 * create it. Theoretically interrupts can only remove (busy)
2216 * pages, not create new associations.
2217 */
2218 if (pindex > 0) {
2219 if (rbehind > pindex) {
2220 rbehind = pindex;
2221 startpindex = 0;
2222 } else {
2223 startpindex = pindex - rbehind;
2224 }
2225
2226 vm_object_hold(object);
2227 for (tpindex = pindex; tpindex > startpindex; --tpindex) {
2228 if (vm_page_lookup(object, tpindex - 1))
2229 break;
2230 }
2231
2232 i = 0;
2233 while (tpindex < pindex) {
2234 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM |
2235 VM_ALLOC_NULL_OK);
2236 if (rtm == NULL) {
2237 for (j = 0; j < i; j++) {
2238 vm_page_free(marray[j]);
2239 }
2240 vm_object_drop(object);
2241 marray[0] = m;
2242 *reqpage = 0;
2243 return 1;
2244 }
2245 marray[i] = rtm;
2246 ++i;
2247 ++tpindex;
2248 }
2249 vm_object_drop(object);
2250 } else {
2251 i = 0;
2252 }
2253
2254 /*
2255 * Assign requested page
2256 */
2257 marray[i] = m;
2258 *reqpage = i;
2259 ++i;
2260
2261 /*
2262 * Scan forwards for read-ahead pages
2263 */
2264 tpindex = pindex + 1;
2265 endpindex = tpindex + rahead;
2266 if (endpindex > object->size)
2267 endpindex = object->size;
2268
2269 vm_object_hold(object);
2270 while (tpindex < endpindex) {
2271 if (vm_page_lookup(object, tpindex))
2272 break;
2273 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM |
2274 VM_ALLOC_NULL_OK);
2275 if (rtm == NULL)
2276 break;
2277 marray[i] = rtm;
2278 ++i;
2279 ++tpindex;
2280 }
2281 vm_object_drop(object);
2282
2283 return (i);
2284 }
2285
2286 #endif
2287
2288 /*
2289 * vm_prefault() provides a quick way of clustering pagefaults into a
2290 * processes address space. It is a "cousin" of pmap_object_init_pt,
2291 * except it runs at page fault time instead of mmap time.
2292 *
2293 * vm.fast_fault Enables pre-faulting zero-fill pages
2294 *
2295 * vm.prefault_pages Number of pages (1/2 negative, 1/2 positive) to
2296 * prefault. Scan stops in either direction when
2297 * a page is found to already exist.
2298 *
2299 * This code used to be per-platform pmap_prefault(). It is now
2300 * machine-independent and enhanced to also pre-fault zero-fill pages
2301 * (see vm.fast_fault) as well as make them writable, which greatly
2302 * reduces the number of page faults programs incur.
2303 *
2304 * Application performance when pre-faulting zero-fill pages is heavily
2305 * dependent on the application. Very tiny applications like /bin/echo
2306 * lose a little performance while applications of any appreciable size
2307 * gain performance. Prefaulting multiple pages also reduces SMP
2308 * congestion and can improve SMP performance significantly.
2309 *
2310 * NOTE! prot may allow writing but this only applies to the top level
2311 * object. If we wind up mapping a page extracted from a backing
2312 * object we have to make sure it is read-only.
2313 *
2314 * NOTE! The caller has already handled any COW operations on the
2315 * vm_map_entry via the normal fault code. Do NOT call this
2316 * shortcut unless the normal fault code has run on this entry.
2317 *
2318 * The related map must be locked.
2319 * No other requirements.
2320 */
2321 static int vm_prefault_pages = 8;
2322 SYSCTL_INT(_vm, OID_AUTO, prefault_pages, CTLFLAG_RW, &vm_prefault_pages, 0,
2323 "Maximum number of pages to pre-fault");
2324 static int vm_fast_fault = 1;
2325 SYSCTL_INT(_vm, OID_AUTO, fast_fault, CTLFLAG_RW, &vm_fast_fault, 0,
2326 "Burst fault zero-fill regions");
2327
2328 /*
2329 * Set PG_NOSYNC if the map entry indicates so, but only if the page
2330 * is not already dirty by other means. This will prevent passive
2331 * filesystem syncing as well as 'sync' from writing out the page.
2332 */
2333 static void
2334 vm_set_nosync(vm_page_t m, vm_map_entry_t entry)
2335 {
2336 if (entry->eflags & MAP_ENTRY_NOSYNC) {
2337 if (m->dirty == 0)
2338 vm_page_flag_set(m, PG_NOSYNC);
2339 } else {
2340 vm_page_flag_clear(m, PG_NOSYNC);
2341 }
2342 }
2343
2344 static void
2345 vm_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry, int prot,
2346 int fault_flags)
2347 {
2348 struct lwp *lp;
2349 vm_page_t m;
2350 vm_offset_t addr;
2351 vm_pindex_t index;
2352 vm_pindex_t pindex;
2353 vm_object_t object;
2354 int pprot;
2355 int i;
2356 int noneg;
2357 int nopos;
2358 int maxpages;
2359
2360 /*
2361 * Get stable max count value, disabled if set to 0
2362 */
2363 maxpages = vm_prefault_pages;
2364 cpu_ccfence();
2365 if (maxpages <= 0)
2366 return;
2367
2368 /*
2369 * We do not currently prefault mappings that use virtual page
2370 * tables. We do not prefault foreign pmaps.
2371 */
2372 if (entry->maptype == VM_MAPTYPE_VPAGETABLE)
2373 return;
2374 lp = curthread->td_lwp;
2375 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace)))
2376 return;
2377
2378 /*
2379 * Limit pre-fault count to 1024 pages.
2380 */
2381 if (maxpages > 1024)
2382 maxpages = 1024;
2383
2384 object = entry->object.vm_object;
2385 KKASSERT(object != NULL);
2386 KKASSERT(object == entry->object.vm_object);
2387 vm_object_hold(object);
2388 vm_object_chain_acquire(object, 0);
2389
2390 noneg = 0;
2391 nopos = 0;
2392 for (i = 0; i < maxpages; ++i) {
2393 vm_object_t lobject;
2394 vm_object_t nobject;
2395 int allocated = 0;
2396 int error;
2397
2398 /*
2399 * This can eat a lot of time on a heavily contended
2400 * machine so yield on the tick if needed.
2401 */
2402 if ((i & 7) == 7)
2403 lwkt_yield();
2404
2405 /*
2406 * Calculate the page to pre-fault, stopping the scan in
2407 * each direction separately if the limit is reached.
2408 */
2409 if (i & 1) {
2410 if (noneg)
2411 continue;
2412 addr = addra - ((i + 1) >> 1) * PAGE_SIZE;
2413 } else {
2414 if (nopos)
2415 continue;
2416 addr = addra + ((i + 2) >> 1) * PAGE_SIZE;
2417 }
2418 if (addr < entry->start) {
2419 noneg = 1;
2420 if (noneg && nopos)
2421 break;
2422 continue;
2423 }
2424 if (addr >= entry->end) {
2425 nopos = 1;
2426 if (noneg && nopos)
2427 break;
2428 continue;
2429 }
2430
2431 /*
2432 * Skip pages already mapped, and stop scanning in that
2433 * direction. When the scan terminates in both directions
2434 * we are done.
2435 */
2436 if (pmap_prefault_ok(pmap, addr) == 0) {
2437 if (i & 1)
2438 noneg = 1;
2439 else
2440 nopos = 1;
2441 if (noneg && nopos)
2442 break;
2443 continue;
2444 }
2445
2446 /*
2447 * Follow the VM object chain to obtain the page to be mapped
2448 * into the pmap.
2449 *
2450 * If we reach the terminal object without finding a page
2451 * and we determine it would be advantageous, then allocate
2452 * a zero-fill page for the base object. The base object
2453 * is guaranteed to be OBJT_DEFAULT for this case.
2454 *
2455 * In order to not have to check the pager via *haspage*()
2456 * we stop if any non-default object is encountered. e.g.
2457 * a vnode or swap object would stop the loop.
2458 */
2459 index = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
2460 lobject = object;
2461 pindex = index;
2462 pprot = prot;
2463
2464 KKASSERT(lobject == entry->object.vm_object);
2465 /*vm_object_hold(lobject); implied */
2466
2467 while ((m = vm_page_lookup_busy_try(lobject, pindex,
2468 TRUE, &error)) == NULL) {
2469 if (lobject->type != OBJT_DEFAULT)
2470 break;
2471 if (lobject->backing_object == NULL) {
2472 if (vm_fast_fault == 0)
2473 break;
2474 if ((prot & VM_PROT_WRITE) == 0 ||
2475 vm_page_count_min(0)) {
2476 break;
2477 }
2478
2479 /*
2480 * NOTE: Allocated from base object
2481 */
2482 m = vm_page_alloc(object, index,
2483 VM_ALLOC_NORMAL |
2484 VM_ALLOC_ZERO |
2485 VM_ALLOC_USE_GD |
2486 VM_ALLOC_NULL_OK);
2487 if (m == NULL)
2488 break;
2489 allocated = 1;
2490 pprot = prot;
2491 /* lobject = object .. not needed */
2492 break;
2493 }
2494 if (lobject->backing_object_offset & PAGE_MASK)
2495 break;
2496 nobject = lobject->backing_object;
2497 vm_object_hold(nobject);
2498 KKASSERT(nobject == lobject->backing_object);
2499 pindex += lobject->backing_object_offset >> PAGE_SHIFT;
2500 if (lobject != object) {
2501 vm_object_lock_swap();
2502 vm_object_drop(lobject);
2503 }
2504 lobject = nobject;
2505 pprot &= ~VM_PROT_WRITE;
2506 vm_object_chain_acquire(lobject, 0);
2507 }
2508
2509 /*
2510 * NOTE: A non-NULL (m) will be associated with lobject if
2511 * it was found there, otherwise it is probably a
2512 * zero-fill page associated with the base object.
2513 *
2514 * Give-up if no page is available.
2515 */
2516 if (m == NULL) {
2517 if (lobject != object) {
2518 #if 0
2519 if (object->backing_object != lobject)
2520 vm_object_hold(object->backing_object);
2521 #endif
2522 vm_object_chain_release_all(
2523 object->backing_object, lobject);
2524 #if 0
2525 if (object->backing_object != lobject)
2526 vm_object_drop(object->backing_object);
2527 #endif
2528 vm_object_drop(lobject);
2529 }
2530 break;
2531 }
2532
2533 /*
2534 * The object must be marked dirty if we are mapping a
2535 * writable page. m->object is either lobject or object,
2536 * both of which are still held. Do this before we
2537 * potentially drop the object.
2538 */
2539 if (pprot & VM_PROT_WRITE)
2540 vm_object_set_writeable_dirty(m->object);
2541
2542 /*
2543 * Do not conditionalize on PG_RAM. If pages are present in
2544 * the VM system we assume optimal caching. If caching is
2545 * not optimal the I/O gravy train will be restarted when we
2546 * hit an unavailable page. We do not want to try to restart
2547 * the gravy train now because we really don't know how much
2548 * of the object has been cached. The cost for restarting
2549 * the gravy train should be low (since accesses will likely
2550 * be I/O bound anyway).
2551 */
2552 if (lobject != object) {
2553 #if 0
2554 if (object->backing_object != lobject)
2555 vm_object_hold(object->backing_object);
2556 #endif
2557 vm_object_chain_release_all(object->backing_object,
2558 lobject);
2559 #if 0
2560 if (object->backing_object != lobject)
2561 vm_object_drop(object->backing_object);
2562 #endif
2563 vm_object_drop(lobject);
2564 }
2565
2566 /*
2567 * Enter the page into the pmap if appropriate. If we had
2568 * allocated the page we have to place it on a queue. If not
2569 * we just have to make sure it isn't on the cache queue
2570 * (pages on the cache queue are not allowed to be mapped).
2571 */
2572 if (allocated) {
2573 /*
2574 * Page must be zerod.
2575 */
2576 if ((m->flags & PG_ZERO) == 0) {
2577 vm_page_zero_fill(m);
2578 } else {
2579 #ifdef PMAP_DEBUG
2580 pmap_page_assertzero(
2581 VM_PAGE_TO_PHYS(m));
2582 #endif
2583 vm_page_flag_clear(m, PG_ZERO);
2584 mycpu->gd_cnt.v_ozfod++;
2585 }
2586 mycpu->gd_cnt.v_zfod++;
2587 m->valid = VM_PAGE_BITS_ALL;
2588
2589 /*
2590 * Handle dirty page case
2591 */
2592 if (pprot & VM_PROT_WRITE)
2593 vm_set_nosync(m, entry);
2594 pmap_enter(pmap, addr, m, pprot, 0, entry);
2595 mycpu->gd_cnt.v_vm_faults++;
2596 if (curthread->td_lwp)
2597 ++curthread->td_lwp->lwp_ru.ru_minflt;
2598 vm_page_deactivate(m);
2599 if (pprot & VM_PROT_WRITE) {
2600 /*vm_object_set_writeable_dirty(m->object);*/
2601 vm_set_nosync(m, entry);
2602 if (fault_flags & VM_FAULT_DIRTY) {
2603 vm_page_dirty(m);
2604 /*XXX*/
2605 swap_pager_unswapped(m);
2606 }
2607 }
2608 vm_page_wakeup(m);
2609 } else if (error) {
2610 /* couldn't busy page, no wakeup */
2611 } else if (
2612 ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
2613 (m->flags & PG_FICTITIOUS) == 0) {
2614 /*
2615 * A fully valid page not undergoing soft I/O can
2616 * be immediately entered into the pmap.
2617 */
2618 if ((m->queue - m->pc) == PQ_CACHE)
2619 vm_page_deactivate(m);
2620 if (pprot & VM_PROT_WRITE) {
2621 /*vm_object_set_writeable_dirty(m->object);*/
2622 vm_set_nosync(m, entry);
2623 if (fault_flags & VM_FAULT_DIRTY) {
2624 vm_page_dirty(m);
2625 /*XXX*/
2626 swap_pager_unswapped(m);
2627 }
2628 }
2629 if (pprot & VM_PROT_WRITE)
2630 vm_set_nosync(m, entry);
2631 pmap_enter(pmap, addr, m, pprot, 0, entry);
2632 mycpu->gd_cnt.v_vm_faults++;
2633 if (curthread->td_lwp)
2634 ++curthread->td_lwp->lwp_ru.ru_minflt;
2635 vm_page_wakeup(m);
2636 } else {
2637 vm_page_wakeup(m);
2638 }
2639 }
2640 vm_object_chain_release(object);
2641 vm_object_drop(object);
2642 }
2643
2644 /*
2645 * Object can be held shared
2646 */
2647 static void
2648 vm_prefault_quick(pmap_t pmap, vm_offset_t addra,
2649 vm_map_entry_t entry, int prot, int fault_flags)
2650 {
2651 struct lwp *lp;
2652 vm_page_t m;
2653 vm_offset_t addr;
2654 vm_pindex_t pindex;
2655 vm_object_t object;
2656 int i;
2657 int noneg;
2658 int nopos;
2659 int maxpages;
2660
2661 /*
2662 * Get stable max count value, disabled if set to 0
2663 */
2664 maxpages = vm_prefault_pages;
2665 cpu_ccfence();
2666 if (maxpages <= 0)
2667 return;
2668
2669 /*
2670 * We do not currently prefault mappings that use virtual page
2671 * tables. We do not prefault foreign pmaps.
2672 */
2673 if (entry->maptype == VM_MAPTYPE_VPAGETABLE)
2674 return;
2675 lp = curthread->td_lwp;
2676 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace)))
2677 return;
2678 object = entry->object.vm_object;
2679 if (object->backing_object != NULL)
2680 return;
2681 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object));
2682
2683 /*
2684 * Limit pre-fault count to 1024 pages.
2685 */
2686 if (maxpages > 1024)
2687 maxpages = 1024;
2688
2689 noneg = 0;
2690 nopos = 0;
2691 for (i = 0; i < maxpages; ++i) {
2692 int error;
2693
2694 /*
2695 * Calculate the page to pre-fault, stopping the scan in
2696 * each direction separately if the limit is reached.
2697 */
2698 if (i & 1) {
2699 if (noneg)
2700 continue;
2701 addr = addra - ((i + 1) >> 1) * PAGE_SIZE;
2702 } else {
2703 if (nopos)
2704 continue;
2705 addr = addra + ((i + 2) >> 1) * PAGE_SIZE;
2706 }
2707 if (addr < entry->start) {
2708 noneg = 1;
2709 if (noneg && nopos)
2710 break;
2711 continue;
2712 }
2713 if (addr >= entry->end) {
2714 nopos = 1;
2715 if (noneg && nopos)
2716 break;
2717 continue;
2718 }
2719
2720 /*
2721 * Skip pages already mapped, and stop scanning in that
2722 * direction. When the scan terminates in both directions
2723 * we are done.
2724 */
2725 if (pmap_prefault_ok(pmap, addr) == 0) {
2726 if (i & 1)
2727 noneg = 1;
2728 else
2729 nopos = 1;
2730 if (noneg && nopos)
2731 break;
2732 continue;
2733 }
2734
2735 /*
2736 * Follow the VM object chain to obtain the page to be mapped
2737 * into the pmap. This version of the prefault code only
2738 * works with terminal objects.
2739 *
2740 * WARNING! We cannot call swap_pager_unswapped() with a
2741 * shared token.
2742 */
2743 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT;
2744
2745 m = vm_page_lookup_busy_try(object, pindex, TRUE, &error);
2746 if (m == NULL || error)
2747 continue;
2748
2749 if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) &&
2750 (m->flags & PG_FICTITIOUS) == 0 &&
2751 ((m->flags & PG_SWAPPED) == 0 ||
2752 (prot & VM_PROT_WRITE) == 0 ||
2753 (fault_flags & VM_FAULT_DIRTY) == 0)) {
2754 /*
2755 * A fully valid page not undergoing soft I/O can
2756 * be immediately entered into the pmap.
2757 */
2758 if ((m->queue - m->pc) == PQ_CACHE)
2759 vm_page_deactivate(m);
2760 if (prot & VM_PROT_WRITE) {
2761 vm_object_set_writeable_dirty(m->object);
2762 vm_set_nosync(m, entry);
2763 if (fault_flags & VM_FAULT_DIRTY) {
2764 vm_page_dirty(m);
2765 /*XXX*/
2766 swap_pager_unswapped(m);
2767 }
2768 }
2769 pmap_enter(pmap, addr, m, prot, 0, entry);
2770 mycpu->gd_cnt.v_vm_faults++;
2771 if (curthread->td_lwp)
2772 ++curthread->td_lwp->lwp_ru.ru_minflt;
2773 }
2774 vm_page_wakeup(m);
2775 }
2776 }
Cache object: 5ea5a1438d17c4ed4355aee9a5ec82d2
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