FreeBSD/Linux Kernel Cross Reference
sys/uvm/uvm_fault.c
1 /* $NetBSD: uvm_fault.c,v 1.125.6.2 2010/11/21 18:09:00 riz Exp $ */
2
3 /*
4 *
5 * Copyright (c) 1997 Charles D. Cranor and 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_fault.c,v 1.1.2.23 1998/02/06 05:29:05 chs Exp
35 */
36
37 /*
38 * uvm_fault.c: fault handler
39 */
40
41 #include <sys/cdefs.h>
42 __KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.125.6.2 2010/11/21 18:09:00 riz Exp $");
43
44 #include "opt_uvmhist.h"
45
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/kernel.h>
49 #include <sys/proc.h>
50 #include <sys/malloc.h>
51 #include <sys/mman.h>
52 #include <sys/user.h>
53
54 #include <uvm/uvm.h>
55
56 /*
57 *
58 * a word on page faults:
59 *
60 * types of page faults we handle:
61 *
62 * CASE 1: upper layer faults CASE 2: lower layer faults
63 *
64 * CASE 1A CASE 1B CASE 2A CASE 2B
65 * read/write1 write>1 read/write +-cow_write/zero
66 * | | | |
67 * +--|--+ +--|--+ +-----+ + | + | +-----+
68 * amap | V | | ----------->new| | | | ^ |
69 * +-----+ +-----+ +-----+ + | + | +--|--+
70 * | | |
71 * +-----+ +-----+ +--|--+ | +--|--+
72 * uobj | d/c | | d/c | | V | +----| |
73 * +-----+ +-----+ +-----+ +-----+
74 *
75 * d/c = don't care
76 *
77 * case [0]: layerless fault
78 * no amap or uobj is present. this is an error.
79 *
80 * case [1]: upper layer fault [anon active]
81 * 1A: [read] or [write with anon->an_ref == 1]
82 * I/O takes place in top level anon and uobj is not touched.
83 * 1B: [write with anon->an_ref > 1]
84 * new anon is alloc'd and data is copied off ["COW"]
85 *
86 * case [2]: lower layer fault [uobj]
87 * 2A: [read on non-NULL uobj] or [write to non-copy_on_write area]
88 * I/O takes place directly in object.
89 * 2B: [write to copy_on_write] or [read on NULL uobj]
90 * data is "promoted" from uobj to a new anon.
91 * if uobj is null, then we zero fill.
92 *
93 * we follow the standard UVM locking protocol ordering:
94 *
95 * MAPS => AMAP => UOBJ => ANON => PAGE QUEUES (PQ)
96 * we hold a PG_BUSY page if we unlock for I/O
97 *
98 *
99 * the code is structured as follows:
100 *
101 * - init the "IN" params in the ufi structure
102 * ReFault:
103 * - do lookups [locks maps], check protection, handle needs_copy
104 * - check for case 0 fault (error)
105 * - establish "range" of fault
106 * - if we have an amap lock it and extract the anons
107 * - if sequential advice deactivate pages behind us
108 * - at the same time check pmap for unmapped areas and anon for pages
109 * that we could map in (and do map it if found)
110 * - check object for resident pages that we could map in
111 * - if (case 2) goto Case2
112 * - >>> handle case 1
113 * - ensure source anon is resident in RAM
114 * - if case 1B alloc new anon and copy from source
115 * - map the correct page in
116 * Case2:
117 * - >>> handle case 2
118 * - ensure source page is resident (if uobj)
119 * - if case 2B alloc new anon and copy from source (could be zero
120 * fill if uobj == NULL)
121 * - map the correct page in
122 * - done!
123 *
124 * note on paging:
125 * if we have to do I/O we place a PG_BUSY page in the correct object,
126 * unlock everything, and do the I/O. when I/O is done we must reverify
127 * the state of the world before assuming that our data structures are
128 * valid. [because mappings could change while the map is unlocked]
129 *
130 * alternative 1: unbusy the page in question and restart the page fault
131 * from the top (ReFault). this is easy but does not take advantage
132 * of the information that we already have from our previous lookup,
133 * although it is possible that the "hints" in the vm_map will help here.
134 *
135 * alternative 2: the system already keeps track of a "version" number of
136 * a map. [i.e. every time you write-lock a map (e.g. to change a
137 * mapping) you bump the version number up by one...] so, we can save
138 * the version number of the map before we release the lock and start I/O.
139 * then when I/O is done we can relock and check the version numbers
140 * to see if anything changed. this might save us some over 1 because
141 * we don't have to unbusy the page and may be less compares(?).
142 *
143 * alternative 3: put in backpointers or a way to "hold" part of a map
144 * in place while I/O is in progress. this could be complex to
145 * implement (especially with structures like amap that can be referenced
146 * by multiple map entries, and figuring out what should wait could be
147 * complex as well...).
148 *
149 * we use alternative 2. given that we are multi-threaded now we may want
150 * to reconsider the choice.
151 */
152
153 /*
154 * local data structures
155 */
156
157 struct uvm_advice {
158 int advice;
159 int nback;
160 int nforw;
161 };
162
163 /*
164 * page range array:
165 * note: index in array must match "advice" value
166 * XXX: borrowed numbers from freebsd. do they work well for us?
167 */
168
169 static const struct uvm_advice uvmadvice[] = {
170 { MADV_NORMAL, 3, 4 },
171 { MADV_RANDOM, 0, 0 },
172 { MADV_SEQUENTIAL, 8, 7},
173 };
174
175 #define UVM_MAXRANGE 16 /* must be MAX() of nback+nforw+1 */
176
177 /*
178 * private prototypes
179 */
180
181 /*
182 * inline functions
183 */
184
185 /*
186 * uvmfault_anonflush: try and deactivate pages in specified anons
187 *
188 * => does not have to deactivate page if it is busy
189 */
190
191 static inline void
192 uvmfault_anonflush(struct vm_anon **anons, int n)
193 {
194 int lcv;
195 struct vm_page *pg;
196
197 for (lcv = 0 ; lcv < n ; lcv++) {
198 if (anons[lcv] == NULL)
199 continue;
200 mutex_enter(&anons[lcv]->an_lock);
201 pg = anons[lcv]->an_page;
202 if (pg && (pg->flags & PG_BUSY) == 0) {
203 mutex_enter(&uvm_pageqlock);
204 if (pg->wire_count == 0) {
205 uvm_pagedeactivate(pg);
206 }
207 mutex_exit(&uvm_pageqlock);
208 }
209 mutex_exit(&anons[lcv]->an_lock);
210 }
211 }
212
213 /*
214 * normal functions
215 */
216
217 /*
218 * uvmfault_amapcopy: clear "needs_copy" in a map.
219 *
220 * => called with VM data structures unlocked (usually, see below)
221 * => we get a write lock on the maps and clear needs_copy for a VA
222 * => if we are out of RAM we sleep (waiting for more)
223 */
224
225 static void
226 uvmfault_amapcopy(struct uvm_faultinfo *ufi)
227 {
228 for (;;) {
229
230 /*
231 * no mapping? give up.
232 */
233
234 if (uvmfault_lookup(ufi, true) == false)
235 return;
236
237 /*
238 * copy if needed.
239 */
240
241 if (UVM_ET_ISNEEDSCOPY(ufi->entry))
242 amap_copy(ufi->map, ufi->entry, AMAP_COPY_NOWAIT,
243 ufi->orig_rvaddr, ufi->orig_rvaddr + 1);
244
245 /*
246 * didn't work? must be out of RAM. unlock and sleep.
247 */
248
249 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) {
250 uvmfault_unlockmaps(ufi, true);
251 uvm_wait("fltamapcopy");
252 continue;
253 }
254
255 /*
256 * got it! unlock and return.
257 */
258
259 uvmfault_unlockmaps(ufi, true);
260 return;
261 }
262 /*NOTREACHED*/
263 }
264
265 /*
266 * uvmfault_anonget: get data in an anon into a non-busy, non-released
267 * page in that anon.
268 *
269 * => maps, amap, and anon locked by caller.
270 * => if we fail (result != 0) we unlock everything.
271 * => if we are successful, we return with everything still locked.
272 * => we don't move the page on the queues [gets moved later]
273 * => if we allocate a new page [we_own], it gets put on the queues.
274 * either way, the result is that the page is on the queues at return time
275 * => for pages which are on loan from a uvm_object (and thus are not
276 * owned by the anon): if successful, we return with the owning object
277 * locked. the caller must unlock this object when it unlocks everything
278 * else.
279 */
280
281 int
282 uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap,
283 struct vm_anon *anon)
284 {
285 bool we_own; /* we own anon's page? */
286 bool locked; /* did we relock? */
287 struct vm_page *pg;
288 int error;
289 UVMHIST_FUNC("uvmfault_anonget"); UVMHIST_CALLED(maphist);
290
291 KASSERT(mutex_owned(&anon->an_lock));
292
293 error = 0;
294 uvmexp.fltanget++;
295 /* bump rusage counters */
296 if (anon->an_page)
297 curlwp->l_ru.ru_minflt++;
298 else
299 curlwp->l_ru.ru_majflt++;
300
301 /*
302 * loop until we get it, or fail.
303 */
304
305 for (;;) {
306 we_own = false; /* true if we set PG_BUSY on a page */
307 pg = anon->an_page;
308
309 /*
310 * if there is a resident page and it is loaned, then anon
311 * may not own it. call out to uvm_anon_lockpage() to ensure
312 * the real owner of the page has been identified and locked.
313 */
314
315 if (pg && pg->loan_count)
316 pg = uvm_anon_lockloanpg(anon);
317
318 /*
319 * page there? make sure it is not busy/released.
320 */
321
322 if (pg) {
323
324 /*
325 * at this point, if the page has a uobject [meaning
326 * we have it on loan], then that uobject is locked
327 * by us! if the page is busy, we drop all the
328 * locks (including uobject) and try again.
329 */
330
331 if ((pg->flags & PG_BUSY) == 0) {
332 UVMHIST_LOG(maphist, "<- OK",0,0,0,0);
333 return (0);
334 }
335 pg->flags |= PG_WANTED;
336 uvmexp.fltpgwait++;
337
338 /*
339 * the last unlock must be an atomic unlock+wait on
340 * the owner of page
341 */
342
343 if (pg->uobject) { /* owner is uobject ? */
344 uvmfault_unlockall(ufi, amap, NULL, anon);
345 UVMHIST_LOG(maphist, " unlock+wait on uobj",0,
346 0,0,0);
347 UVM_UNLOCK_AND_WAIT(pg,
348 &pg->uobject->vmobjlock,
349 false, "anonget1",0);
350 } else {
351 /* anon owns page */
352 uvmfault_unlockall(ufi, amap, NULL, NULL);
353 UVMHIST_LOG(maphist, " unlock+wait on anon",0,
354 0,0,0);
355 UVM_UNLOCK_AND_WAIT(pg,&anon->an_lock,0,
356 "anonget2",0);
357 }
358 } else {
359 #if defined(VMSWAP)
360
361 /*
362 * no page, we must try and bring it in.
363 */
364
365 pg = uvm_pagealloc(NULL, 0, anon, 0);
366 if (pg == NULL) { /* out of RAM. */
367 uvmfault_unlockall(ufi, amap, NULL, anon);
368 uvmexp.fltnoram++;
369 UVMHIST_LOG(maphist, " noram -- UVM_WAIT",0,
370 0,0,0);
371 if (!uvm_reclaimable()) {
372 return ENOMEM;
373 }
374 uvm_wait("flt_noram1");
375 } else {
376 /* we set the PG_BUSY bit */
377 we_own = true;
378 uvmfault_unlockall(ufi, amap, NULL, anon);
379
380 /*
381 * we are passing a PG_BUSY+PG_FAKE+PG_CLEAN
382 * page into the uvm_swap_get function with
383 * all data structures unlocked. note that
384 * it is ok to read an_swslot here because
385 * we hold PG_BUSY on the page.
386 */
387 uvmexp.pageins++;
388 error = uvm_swap_get(pg, anon->an_swslot,
389 PGO_SYNCIO);
390
391 /*
392 * we clean up after the i/o below in the
393 * "we_own" case
394 */
395 }
396 #else /* defined(VMSWAP) */
397 panic("%s: no page", __func__);
398 #endif /* defined(VMSWAP) */
399 }
400
401 /*
402 * now relock and try again
403 */
404
405 locked = uvmfault_relock(ufi);
406 if (locked && amap != NULL) {
407 amap_lock(amap);
408 }
409 if (locked || we_own)
410 mutex_enter(&anon->an_lock);
411
412 /*
413 * if we own the page (i.e. we set PG_BUSY), then we need
414 * to clean up after the I/O. there are three cases to
415 * consider:
416 * [1] page released during I/O: free anon and ReFault.
417 * [2] I/O not OK. free the page and cause the fault
418 * to fail.
419 * [3] I/O OK! activate the page and sync with the
420 * non-we_own case (i.e. drop anon lock if not locked).
421 */
422
423 if (we_own) {
424 #if defined(VMSWAP)
425 if (pg->flags & PG_WANTED) {
426 wakeup(pg);
427 }
428 if (error) {
429
430 /*
431 * remove the swap slot from the anon
432 * and mark the anon as having no real slot.
433 * don't free the swap slot, thus preventing
434 * it from being used again.
435 */
436
437 if (anon->an_swslot > 0)
438 uvm_swap_markbad(anon->an_swslot, 1);
439 anon->an_swslot = SWSLOT_BAD;
440
441 if ((pg->flags & PG_RELEASED) != 0)
442 goto released;
443
444 /*
445 * note: page was never !PG_BUSY, so it
446 * can't be mapped and thus no need to
447 * pmap_page_protect it...
448 */
449
450 mutex_enter(&uvm_pageqlock);
451 uvm_pagefree(pg);
452 mutex_exit(&uvm_pageqlock);
453
454 if (locked)
455 uvmfault_unlockall(ufi, amap, NULL,
456 anon);
457 else
458 mutex_exit(&anon->an_lock);
459 UVMHIST_LOG(maphist, "<- ERROR", 0,0,0,0);
460 return error;
461 }
462
463 if ((pg->flags & PG_RELEASED) != 0) {
464 released:
465 KASSERT(anon->an_ref == 0);
466
467 /*
468 * released while we unlocked amap.
469 */
470
471 if (locked)
472 uvmfault_unlockall(ufi, amap, NULL,
473 NULL);
474
475 uvm_anon_release(anon);
476
477 if (error) {
478 UVMHIST_LOG(maphist,
479 "<- ERROR/RELEASED", 0,0,0,0);
480 return error;
481 }
482
483 UVMHIST_LOG(maphist, "<- RELEASED", 0,0,0,0);
484 return ERESTART;
485 }
486
487 /*
488 * we've successfully read the page, activate it.
489 */
490
491 mutex_enter(&uvm_pageqlock);
492 uvm_pageactivate(pg);
493 mutex_exit(&uvm_pageqlock);
494 pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE);
495 UVM_PAGE_OWN(pg, NULL);
496 if (!locked)
497 mutex_exit(&anon->an_lock);
498 #else /* defined(VMSWAP) */
499 panic("%s: we_own", __func__);
500 #endif /* defined(VMSWAP) */
501 }
502
503 /*
504 * we were not able to relock. restart fault.
505 */
506
507 if (!locked) {
508 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0);
509 return (ERESTART);
510 }
511
512 /*
513 * verify no one has touched the amap and moved the anon on us.
514 */
515
516 if (ufi != NULL &&
517 amap_lookup(&ufi->entry->aref,
518 ufi->orig_rvaddr - ufi->entry->start) != anon) {
519
520 uvmfault_unlockall(ufi, amap, NULL, anon);
521 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0);
522 return (ERESTART);
523 }
524
525 /*
526 * try it again!
527 */
528
529 uvmexp.fltanretry++;
530 continue;
531 }
532 /*NOTREACHED*/
533 }
534
535 /*
536 * uvmfault_promote: promote data to a new anon. used for 1B and 2B.
537 *
538 * 1. allocate an anon and a page.
539 * 2. fill its contents.
540 * 3. put it into amap.
541 *
542 * => if we fail (result != 0) we unlock everything.
543 * => on success, return a new locked anon via 'nanon'.
544 * (*nanon)->an_page will be a resident, locked, dirty page.
545 */
546
547 static int
548 uvmfault_promote(struct uvm_faultinfo *ufi,
549 struct vm_anon *oanon,
550 struct vm_page *uobjpage,
551 struct vm_anon **nanon, /* OUT: allocated anon */
552 struct vm_anon **spare)
553 {
554 struct vm_amap *amap = ufi->entry->aref.ar_amap;
555 struct uvm_object *uobj;
556 struct vm_anon *anon;
557 struct vm_page *pg;
558 struct vm_page *opg;
559 int error;
560 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist);
561
562 if (oanon) {
563 /* anon COW */
564 opg = oanon->an_page;
565 KASSERT(opg != NULL);
566 KASSERT(opg->uobject == NULL || opg->loan_count > 0);
567 } else if (uobjpage != PGO_DONTCARE) {
568 /* object-backed COW */
569 opg = uobjpage;
570 } else {
571 /* ZFOD */
572 opg = NULL;
573 }
574 if (opg != NULL) {
575 uobj = opg->uobject;
576 } else {
577 uobj = NULL;
578 }
579
580 KASSERT(amap != NULL);
581 KASSERT(uobjpage != NULL);
582 KASSERT(uobjpage == PGO_DONTCARE || (uobjpage->flags & PG_BUSY) != 0);
583 KASSERT(mutex_owned(&amap->am_l));
584 KASSERT(oanon == NULL || mutex_owned(&oanon->an_lock));
585 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock));
586 #if 0
587 KASSERT(*spare == NULL || !mutex_owned(&(*spare)->an_lock));
588 #endif
589
590 if (*spare != NULL) {
591 anon = *spare;
592 *spare = NULL;
593 mutex_enter(&anon->an_lock);
594 } else if (ufi->map != kernel_map) {
595 anon = uvm_analloc();
596 } else {
597 UVMHIST_LOG(maphist, "kernel_map, unlock and retry", 0,0,0,0);
598
599 /*
600 * we can't allocate anons with kernel_map locked.
601 */
602
603 uvm_page_unbusy(&uobjpage, 1);
604 uvmfault_unlockall(ufi, amap, uobj, oanon);
605
606 *spare = uvm_analloc();
607 if (*spare == NULL) {
608 goto nomem;
609 }
610 mutex_exit(&(*spare)->an_lock);
611 error = ERESTART;
612 goto done;
613 }
614 if (anon) {
615
616 /*
617 * The new anon is locked.
618 *
619 * if opg == NULL, we want a zero'd, dirty page,
620 * so have uvm_pagealloc() do that for us.
621 */
622
623 pg = uvm_pagealloc(NULL, 0, anon,
624 (opg == NULL) ? UVM_PGA_ZERO : 0);
625 } else {
626 pg = NULL;
627 }
628
629 /*
630 * out of memory resources?
631 */
632
633 if (pg == NULL) {
634 /* save anon for the next try. */
635 if (anon != NULL) {
636 mutex_exit(&anon->an_lock);
637 *spare = anon;
638 }
639
640 /* unlock and fail ... */
641 uvm_page_unbusy(&uobjpage, 1);
642 uvmfault_unlockall(ufi, amap, uobj, oanon);
643 nomem:
644 if (!uvm_reclaimable()) {
645 UVMHIST_LOG(maphist, "out of VM", 0,0,0,0);
646 uvmexp.fltnoanon++;
647 error = ENOMEM;
648 goto done;
649 }
650
651 UVMHIST_LOG(maphist, "out of RAM, waiting for more", 0,0,0,0);
652 uvmexp.fltnoram++;
653 uvm_wait("flt_noram5");
654 error = ERESTART;
655 goto done;
656 }
657
658 /* copy page [pg now dirty] */
659 if (opg) {
660 uvm_pagecopy(opg, pg);
661 }
662
663 amap_add(&ufi->entry->aref, ufi->orig_rvaddr - ufi->entry->start, anon,
664 oanon != NULL);
665
666 *nanon = anon;
667 error = 0;
668 done:
669 return error;
670 }
671
672
673 /*
674 * F A U L T - m a i n e n t r y p o i n t
675 */
676
677 /*
678 * uvm_fault: page fault handler
679 *
680 * => called from MD code to resolve a page fault
681 * => VM data structures usually should be unlocked. however, it is
682 * possible to call here with the main map locked if the caller
683 * gets a write lock, sets it recusive, and then calls us (c.f.
684 * uvm_map_pageable). this should be avoided because it keeps
685 * the map locked off during I/O.
686 * => MUST NEVER BE CALLED IN INTERRUPT CONTEXT
687 */
688
689 #define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \
690 ~VM_PROT_WRITE : VM_PROT_ALL)
691
692 /* fault_flag values passed from uvm_fault_wire to uvm_fault_internal */
693 #define UVM_FAULT_WIRE 1
694 #define UVM_FAULT_WIREMAX 2
695
696 int
697 uvm_fault_internal(struct vm_map *orig_map, vaddr_t vaddr,
698 vm_prot_t access_type, int fault_flag)
699 {
700 struct uvm_faultinfo ufi;
701 vm_prot_t enter_prot, check_prot;
702 bool wired, narrow, promote, locked, shadowed, wire_fault, cow_now;
703 int npages, nback, nforw, centeridx, error, lcv, gotpages;
704 vaddr_t startva, currva;
705 voff_t uoff;
706 struct vm_amap *amap;
707 struct uvm_object *uobj;
708 struct vm_anon *anons_store[UVM_MAXRANGE], **anons, *anon, *oanon;
709 struct vm_anon *anon_spare;
710 struct vm_page *pages[UVM_MAXRANGE], *pg, *uobjpage;
711 UVMHIST_FUNC("uvm_fault"); UVMHIST_CALLED(maphist);
712
713 UVMHIST_LOG(maphist, "(map=0x%x, vaddr=0x%x, at=%d, ff=%d)",
714 orig_map, vaddr, access_type, fault_flag);
715
716 anon = anon_spare = NULL;
717 pg = NULL;
718
719 uvmexp.faults++; /* XXX: locking? */
720
721 /*
722 * init the IN parameters in the ufi
723 */
724
725 ufi.orig_map = orig_map;
726 ufi.orig_rvaddr = trunc_page(vaddr);
727 ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */
728 wire_fault = (fault_flag > 0);
729 if (wire_fault)
730 narrow = true; /* don't look for neighborhood
731 * pages on wire */
732 else
733 narrow = false; /* normal fault */
734
735 /*
736 * "goto ReFault" means restart the page fault from ground zero.
737 */
738 ReFault:
739
740 /*
741 * lookup and lock the maps
742 */
743
744 if (uvmfault_lookup(&ufi, false) == false) {
745 UVMHIST_LOG(maphist, "<- no mapping @ 0x%x", vaddr, 0,0,0);
746 error = EFAULT;
747 goto done;
748 }
749 /* locked: maps(read) */
750
751 #ifdef DIAGNOSTIC
752 if ((ufi.map->flags & VM_MAP_PAGEABLE) == 0) {
753 printf("Page fault on non-pageable map:\n");
754 printf("ufi.map = %p\n", ufi.map);
755 printf("ufi.orig_map = %p\n", ufi.orig_map);
756 printf("ufi.orig_rvaddr = 0x%lx\n", (u_long) ufi.orig_rvaddr);
757 panic("uvm_fault: (ufi.map->flags & VM_MAP_PAGEABLE) == 0");
758 }
759 #endif
760
761 /*
762 * check protection
763 */
764
765 check_prot = fault_flag == UVM_FAULT_WIREMAX ?
766 ufi.entry->max_protection : ufi.entry->protection;
767 if ((check_prot & access_type) != access_type) {
768 UVMHIST_LOG(maphist,
769 "<- protection failure (prot=0x%x, access=0x%x)",
770 ufi.entry->protection, access_type, 0, 0);
771 uvmfault_unlockmaps(&ufi, false);
772 error = EACCES;
773 goto done;
774 }
775
776 /*
777 * "enter_prot" is the protection we want to enter the page in at.
778 * for certain pages (e.g. copy-on-write pages) this protection can
779 * be more strict than ufi.entry->protection. "wired" means either
780 * the entry is wired or we are fault-wiring the pg.
781 */
782
783 enter_prot = ufi.entry->protection;
784 wired = VM_MAPENT_ISWIRED(ufi.entry) || wire_fault;
785 if (wired) {
786 access_type = enter_prot; /* full access for wired */
787 cow_now = (check_prot & VM_PROT_WRITE) != 0;
788 } else {
789 cow_now = (access_type & VM_PROT_WRITE) != 0;
790 }
791
792 /*
793 * handle "needs_copy" case. if we need to copy the amap we will
794 * have to drop our readlock and relock it with a write lock. (we
795 * need a write lock to change anything in a map entry [e.g.
796 * needs_copy]).
797 */
798
799 if (UVM_ET_ISNEEDSCOPY(ufi.entry)) {
800 if (cow_now || (ufi.entry->object.uvm_obj == NULL)) {
801 KASSERT(fault_flag != UVM_FAULT_WIREMAX);
802 /* need to clear */
803 UVMHIST_LOG(maphist,
804 " need to clear needs_copy and refault",0,0,0,0);
805 uvmfault_unlockmaps(&ufi, false);
806 uvmfault_amapcopy(&ufi);
807 uvmexp.fltamcopy++;
808 goto ReFault;
809
810 } else {
811
812 /*
813 * ensure that we pmap_enter page R/O since
814 * needs_copy is still true
815 */
816
817 enter_prot &= ~VM_PROT_WRITE;
818 }
819 }
820
821 /*
822 * identify the players
823 */
824
825 amap = ufi.entry->aref.ar_amap; /* top layer */
826 uobj = ufi.entry->object.uvm_obj; /* bottom layer */
827
828 /*
829 * check for a case 0 fault. if nothing backing the entry then
830 * error now.
831 */
832
833 if (amap == NULL && uobj == NULL) {
834 uvmfault_unlockmaps(&ufi, false);
835 UVMHIST_LOG(maphist,"<- no backing store, no overlay",0,0,0,0);
836 error = EFAULT;
837 goto done;
838 }
839
840 /*
841 * establish range of interest based on advice from mapper
842 * and then clip to fit map entry. note that we only want
843 * to do this the first time through the fault. if we
844 * ReFault we will disable this by setting "narrow" to true.
845 */
846
847 if (narrow == false) {
848
849 /* wide fault (!narrow) */
850 KASSERT(uvmadvice[ufi.entry->advice].advice ==
851 ufi.entry->advice);
852 nback = MIN(uvmadvice[ufi.entry->advice].nback,
853 (ufi.orig_rvaddr - ufi.entry->start) >> PAGE_SHIFT);
854 startva = ufi.orig_rvaddr - (nback << PAGE_SHIFT);
855 nforw = MIN(uvmadvice[ufi.entry->advice].nforw,
856 ((ufi.entry->end - ufi.orig_rvaddr) >>
857 PAGE_SHIFT) - 1);
858 /*
859 * note: "-1" because we don't want to count the
860 * faulting page as forw
861 */
862 npages = nback + nforw + 1;
863 centeridx = nback;
864
865 narrow = true; /* ensure only once per-fault */
866
867 } else {
868
869 /* narrow fault! */
870 nback = nforw = 0;
871 startva = ufi.orig_rvaddr;
872 npages = 1;
873 centeridx = 0;
874
875 }
876
877 /* locked: maps(read) */
878 UVMHIST_LOG(maphist, " narrow=%d, back=%d, forw=%d, startva=0x%x",
879 narrow, nback, nforw, startva);
880 UVMHIST_LOG(maphist, " entry=0x%x, amap=0x%x, obj=0x%x", ufi.entry,
881 amap, uobj, 0);
882
883 /*
884 * if we've got an amap, lock it and extract current anons.
885 */
886
887 if (amap) {
888 amap_lock(amap);
889 anons = anons_store;
890 amap_lookups(&ufi.entry->aref, startva - ufi.entry->start,
891 anons, npages);
892 } else {
893 anons = NULL; /* to be safe */
894 }
895
896 /* locked: maps(read), amap(if there) */
897 KASSERT(amap == NULL || mutex_owned(&amap->am_l));
898
899 /*
900 * for MADV_SEQUENTIAL mappings we want to deactivate the back pages
901 * now and then forget about them (for the rest of the fault).
902 */
903
904 if (ufi.entry->advice == MADV_SEQUENTIAL && nback != 0) {
905
906 UVMHIST_LOG(maphist, " MADV_SEQUENTIAL: flushing backpages",
907 0,0,0,0);
908 /* flush back-page anons? */
909 if (amap)
910 uvmfault_anonflush(anons, nback);
911
912 /* flush object? */
913 if (uobj) {
914 uoff = (startva - ufi.entry->start) + ufi.entry->offset;
915 mutex_enter(&uobj->vmobjlock);
916 (void) (uobj->pgops->pgo_put)(uobj, uoff, uoff +
917 (nback << PAGE_SHIFT), PGO_DEACTIVATE);
918 }
919
920 /* now forget about the backpages */
921 if (amap)
922 anons += nback;
923 startva += (nback << PAGE_SHIFT);
924 npages -= nback;
925 nback = centeridx = 0;
926 }
927
928 /* locked: maps(read), amap(if there) */
929 KASSERT(amap == NULL || mutex_owned(&amap->am_l));
930
931 /*
932 * map in the backpages and frontpages we found in the amap in hopes
933 * of preventing future faults. we also init the pages[] array as
934 * we go.
935 */
936
937 currva = startva;
938 shadowed = false;
939 for (lcv = 0 ; lcv < npages ; lcv++, currva += PAGE_SIZE) {
940
941 /*
942 * dont play with VAs that are already mapped
943 * except for center)
944 */
945 if (lcv != centeridx &&
946 pmap_extract(ufi.orig_map->pmap, currva, NULL)) {
947 pages[lcv] = PGO_DONTCARE;
948 continue;
949 }
950
951 /*
952 * unmapped or center page. check if any anon at this level.
953 */
954 if (amap == NULL || anons[lcv] == NULL) {
955 pages[lcv] = NULL;
956 continue;
957 }
958
959 /*
960 * check for present page and map if possible. re-activate it.
961 */
962
963 pages[lcv] = PGO_DONTCARE;
964 if (lcv == centeridx) { /* save center for later! */
965 shadowed = true;
966 continue;
967 }
968 anon = anons[lcv];
969 mutex_enter(&anon->an_lock);
970 /* ignore loaned pages */
971 if (anon->an_page && anon->an_page->loan_count == 0 &&
972 (anon->an_page->flags & PG_BUSY) == 0) {
973 mutex_enter(&uvm_pageqlock);
974 uvm_pageenqueue(anon->an_page);
975 mutex_exit(&uvm_pageqlock);
976 UVMHIST_LOG(maphist,
977 " MAPPING: n anon: pm=0x%x, va=0x%x, pg=0x%x",
978 ufi.orig_map->pmap, currva, anon->an_page, 0);
979 uvmexp.fltnamap++;
980
981 /*
982 * Since this isn't the page that's actually faulting,
983 * ignore pmap_enter() failures; it's not critical
984 * that we enter these right now.
985 */
986
987 (void) pmap_enter(ufi.orig_map->pmap, currva,
988 VM_PAGE_TO_PHYS(anon->an_page),
989 (anon->an_ref > 1) ? (enter_prot & ~VM_PROT_WRITE) :
990 enter_prot,
991 PMAP_CANFAIL |
992 (VM_MAPENT_ISWIRED(ufi.entry) ? PMAP_WIRED : 0));
993 }
994 pmap_update(ufi.orig_map->pmap);
995 mutex_exit(&anon->an_lock);
996 }
997
998 /* locked: maps(read), amap(if there) */
999 KASSERT(amap == NULL || mutex_owned(&amap->am_l));
1000 /* (shadowed == true) if there is an anon at the faulting address */
1001 UVMHIST_LOG(maphist, " shadowed=%d, will_get=%d", shadowed,
1002 (uobj && shadowed == false),0,0);
1003
1004 /*
1005 * note that if we are really short of RAM we could sleep in the above
1006 * call to pmap_enter with everything locked. bad?
1007 *
1008 * XXX Actually, that is bad; pmap_enter() should just fail in that
1009 * XXX case. --thorpej
1010 */
1011
1012 /*
1013 * if the desired page is not shadowed by the amap and we have a
1014 * backing object, then we check to see if the backing object would
1015 * prefer to handle the fault itself (rather than letting us do it
1016 * with the usual pgo_get hook). the backing object signals this by
1017 * providing a pgo_fault routine.
1018 */
1019
1020 if (uobj && shadowed == false && uobj->pgops->pgo_fault != NULL) {
1021 mutex_enter(&uobj->vmobjlock);
1022 /* locked: maps(read), amap (if there), uobj */
1023 error = uobj->pgops->pgo_fault(&ufi, startva, pages, npages,
1024 centeridx, access_type, PGO_LOCKED|PGO_SYNCIO);
1025
1026 /* locked: nothing, pgo_fault has unlocked everything */
1027
1028 if (error == ERESTART)
1029 goto ReFault; /* try again! */
1030 /*
1031 * object fault routine responsible for pmap_update().
1032 */
1033 goto done;
1034 }
1035
1036 /*
1037 * now, if the desired page is not shadowed by the amap and we have
1038 * a backing object that does not have a special fault routine, then
1039 * we ask (with pgo_get) the object for resident pages that we care
1040 * about and attempt to map them in. we do not let pgo_get block
1041 * (PGO_LOCKED).
1042 */
1043
1044 if (uobj && shadowed == false) {
1045 mutex_enter(&uobj->vmobjlock);
1046 /* locked (!shadowed): maps(read), amap (if there), uobj */
1047 /*
1048 * the following call to pgo_get does _not_ change locking state
1049 */
1050
1051 uvmexp.fltlget++;
1052 gotpages = npages;
1053 (void) uobj->pgops->pgo_get(uobj, ufi.entry->offset +
1054 (startva - ufi.entry->start),
1055 pages, &gotpages, centeridx,
1056 access_type & MASK(ufi.entry),
1057 ufi.entry->advice, PGO_LOCKED);
1058
1059 /*
1060 * check for pages to map, if we got any
1061 */
1062
1063 uobjpage = NULL;
1064
1065 if (gotpages) {
1066 currva = startva;
1067 for (lcv = 0; lcv < npages;
1068 lcv++, currva += PAGE_SIZE) {
1069 struct vm_page *curpg;
1070 bool readonly;
1071
1072 curpg = pages[lcv];
1073 if (curpg == NULL || curpg == PGO_DONTCARE) {
1074 continue;
1075 }
1076 KASSERT(curpg->uobject == uobj);
1077
1078 /*
1079 * if center page is resident and not
1080 * PG_BUSY|PG_RELEASED then pgo_get
1081 * made it PG_BUSY for us and gave
1082 * us a handle to it. remember this
1083 * page as "uobjpage." (for later use).
1084 */
1085
1086 if (lcv == centeridx) {
1087 uobjpage = curpg;
1088 UVMHIST_LOG(maphist, " got uobjpage "
1089 "(0x%x) with locked get",
1090 uobjpage, 0,0,0);
1091 continue;
1092 }
1093
1094 /*
1095 * calling pgo_get with PGO_LOCKED returns us
1096 * pages which are neither busy nor released,
1097 * so we don't need to check for this.
1098 * we can just directly enter the pages.
1099 */
1100
1101 mutex_enter(&uvm_pageqlock);
1102 uvm_pageenqueue(curpg);
1103 mutex_exit(&uvm_pageqlock);
1104 UVMHIST_LOG(maphist,
1105 " MAPPING: n obj: pm=0x%x, va=0x%x, pg=0x%x",
1106 ufi.orig_map->pmap, currva, curpg, 0);
1107 uvmexp.fltnomap++;
1108
1109 /*
1110 * Since this page isn't the page that's
1111 * actually faulting, ignore pmap_enter()
1112 * failures; it's not critical that we
1113 * enter these right now.
1114 */
1115 KASSERT((curpg->flags & PG_PAGEOUT) == 0);
1116 KASSERT((curpg->flags & PG_RELEASED) == 0);
1117 KASSERT(!UVM_OBJ_IS_CLEAN(curpg->uobject) ||
1118 (curpg->flags & PG_CLEAN) != 0);
1119 readonly = (curpg->flags & PG_RDONLY)
1120 || (curpg->loan_count > 0)
1121 || UVM_OBJ_NEEDS_WRITEFAULT(curpg->uobject);
1122
1123 (void) pmap_enter(ufi.orig_map->pmap, currva,
1124 VM_PAGE_TO_PHYS(curpg),
1125 readonly ?
1126 enter_prot & ~VM_PROT_WRITE :
1127 enter_prot & MASK(ufi.entry),
1128 PMAP_CANFAIL |
1129 (wired ? PMAP_WIRED : 0));
1130
1131 /*
1132 * NOTE: page can't be PG_WANTED or PG_RELEASED
1133 * because we've held the lock the whole time
1134 * we've had the handle.
1135 */
1136 KASSERT((curpg->flags & PG_WANTED) == 0);
1137 KASSERT((curpg->flags & PG_RELEASED) == 0);
1138
1139 curpg->flags &= ~(PG_BUSY);
1140 UVM_PAGE_OWN(curpg, NULL);
1141 }
1142 pmap_update(ufi.orig_map->pmap);
1143 }
1144 } else {
1145 uobjpage = NULL;
1146 }
1147
1148 /* locked (shadowed): maps(read), amap */
1149 /* locked (!shadowed): maps(read), amap(if there),
1150 uobj(if !null), uobjpage(if !null) */
1151 if (shadowed) {
1152 KASSERT(mutex_owned(&amap->am_l));
1153 } else {
1154 KASSERT(amap == NULL || mutex_owned(&amap->am_l));
1155 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock));
1156 KASSERT(uobjpage == NULL || (uobjpage->flags & PG_BUSY) != 0);
1157 }
1158
1159 /*
1160 * note that at this point we are done with any front or back pages.
1161 * we are now going to focus on the center page (i.e. the one we've
1162 * faulted on). if we have faulted on the top (anon) layer
1163 * [i.e. case 1], then the anon we want is anons[centeridx] (we have
1164 * not touched it yet). if we have faulted on the bottom (uobj)
1165 * layer [i.e. case 2] and the page was both present and available,
1166 * then we've got a pointer to it as "uobjpage" and we've already
1167 * made it BUSY.
1168 */
1169
1170 /*
1171 * there are four possible cases we must address: 1A, 1B, 2A, and 2B
1172 */
1173
1174 /*
1175 * redirect case 2: if we are not shadowed, go to case 2.
1176 */
1177
1178 if (shadowed == false)
1179 goto Case2;
1180
1181 /* locked: maps(read), amap */
1182
1183 /*
1184 * handle case 1: fault on an anon in our amap
1185 */
1186
1187 anon = anons[centeridx];
1188 UVMHIST_LOG(maphist, " case 1 fault: anon=0x%x", anon, 0,0,0);
1189 mutex_enter(&anon->an_lock);
1190
1191 /* locked: maps(read), amap, anon */
1192 KASSERT(mutex_owned(&amap->am_l));
1193 KASSERT(mutex_owned(&anon->an_lock));
1194
1195 /*
1196 * no matter if we have case 1A or case 1B we are going to need to
1197 * have the anon's memory resident. ensure that now.
1198 */
1199
1200 /*
1201 * let uvmfault_anonget do the dirty work.
1202 * if it fails (!OK) it will unlock everything for us.
1203 * if it succeeds, locks are still valid and locked.
1204 * also, if it is OK, then the anon's page is on the queues.
1205 * if the page is on loan from a uvm_object, then anonget will
1206 * lock that object for us if it does not fail.
1207 */
1208
1209 error = uvmfault_anonget(&ufi, amap, anon);
1210 switch (error) {
1211 case 0:
1212 break;
1213
1214 case ERESTART:
1215 goto ReFault;
1216
1217 case EAGAIN:
1218 tsleep(&lbolt, PVM, "fltagain1", 0);
1219 goto ReFault;
1220
1221 default:
1222 goto done;
1223 }
1224
1225 /*
1226 * uobj is non null if the page is on loan from an object (i.e. uobj)
1227 */
1228
1229 uobj = anon->an_page->uobject; /* locked by anonget if !NULL */
1230
1231 /* locked: maps(read), amap, anon, uobj(if one) */
1232 KASSERT(mutex_owned(&amap->am_l));
1233 KASSERT(mutex_owned(&anon->an_lock));
1234 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock));
1235
1236 /*
1237 * special handling for loaned pages
1238 */
1239
1240 if (anon->an_page->loan_count) {
1241
1242 if (!cow_now) {
1243
1244 /*
1245 * for read faults on loaned pages we just cap the
1246 * protection at read-only.
1247 */
1248
1249 enter_prot = enter_prot & ~VM_PROT_WRITE;
1250
1251 } else {
1252 /*
1253 * note that we can't allow writes into a loaned page!
1254 *
1255 * if we have a write fault on a loaned page in an
1256 * anon then we need to look at the anon's ref count.
1257 * if it is greater than one then we are going to do
1258 * a normal copy-on-write fault into a new anon (this
1259 * is not a problem). however, if the reference count
1260 * is one (a case where we would normally allow a
1261 * write directly to the page) then we need to kill
1262 * the loan before we continue.
1263 */
1264
1265 /* >1 case is already ok */
1266 if (anon->an_ref == 1) {
1267
1268 /* get new un-owned replacement page */
1269 pg = uvm_pagealloc(NULL, 0, NULL, 0);
1270 if (pg == NULL) {
1271 uvmfault_unlockall(&ufi, amap, uobj,
1272 anon);
1273 uvm_wait("flt_noram2");
1274 goto ReFault;
1275 }
1276
1277 /*
1278 * copy data, kill loan, and drop uobj lock
1279 * (if any)
1280 */
1281 /* copy old -> new */
1282 uvm_pagecopy(anon->an_page, pg);
1283
1284 /* force reload */
1285 pmap_page_protect(anon->an_page, VM_PROT_NONE);
1286 mutex_enter(&uvm_pageqlock); /* KILL loan */
1287
1288 anon->an_page->uanon = NULL;
1289 /* in case we owned */
1290 anon->an_page->pqflags &= ~PQ_ANON;
1291
1292 if (uobj) {
1293 /* if we were receiver of loan */
1294 anon->an_page->loan_count--;
1295 } else {
1296 /*
1297 * we were the lender (A->K); need
1298 * to remove the page from pageq's.
1299 */
1300 uvm_pagedequeue(anon->an_page);
1301 }
1302
1303 if (uobj) {
1304 mutex_exit(&uobj->vmobjlock);
1305 uobj = NULL;
1306 }
1307
1308 /* install new page in anon */
1309 anon->an_page = pg;
1310 pg->uanon = anon;
1311 pg->pqflags |= PQ_ANON;
1312
1313 uvm_pageactivate(pg);
1314 mutex_exit(&uvm_pageqlock);
1315
1316 pg->flags &= ~(PG_BUSY|PG_FAKE);
1317 UVM_PAGE_OWN(pg, NULL);
1318
1319 /* done! */
1320 } /* ref == 1 */
1321 } /* write fault */
1322 } /* loan count */
1323
1324 /*
1325 * if we are case 1B then we will need to allocate a new blank
1326 * anon to transfer the data into. note that we have a lock
1327 * on anon, so no one can busy or release the page until we are done.
1328 * also note that the ref count can't drop to zero here because
1329 * it is > 1 and we are only dropping one ref.
1330 *
1331 * in the (hopefully very rare) case that we are out of RAM we
1332 * will unlock, wait for more RAM, and refault.
1333 *
1334 * if we are out of anon VM we kill the process (XXX: could wait?).
1335 */
1336
1337 if (cow_now && anon->an_ref > 1) {
1338
1339 UVMHIST_LOG(maphist, " case 1B: COW fault",0,0,0,0);
1340 uvmexp.flt_acow++;
1341 oanon = anon; /* oanon = old, locked anon */
1342
1343 error = uvmfault_promote(&ufi, oanon, PGO_DONTCARE,
1344 &anon, &anon_spare);
1345 switch (error) {
1346 case 0:
1347 break;
1348 case ERESTART:
1349 goto ReFault;
1350 default:
1351 goto done;
1352 }
1353
1354 pg = anon->an_page;
1355 mutex_enter(&uvm_pageqlock);
1356 uvm_pageactivate(pg);
1357 mutex_exit(&uvm_pageqlock);
1358 pg->flags &= ~(PG_BUSY|PG_FAKE);
1359 UVM_PAGE_OWN(pg, NULL);
1360
1361 /* deref: can not drop to zero here by defn! */
1362 oanon->an_ref--;
1363
1364 /*
1365 * note: oanon is still locked, as is the new anon. we
1366 * need to check for this later when we unlock oanon; if
1367 * oanon != anon, we'll have to unlock anon, too.
1368 */
1369
1370 } else {
1371
1372 uvmexp.flt_anon++;
1373 oanon = anon; /* old, locked anon is same as anon */
1374 pg = anon->an_page;
1375 if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */
1376 enter_prot = enter_prot & ~VM_PROT_WRITE;
1377
1378 }
1379
1380 /* locked: maps(read), amap, oanon, anon (if different from oanon) */
1381 KASSERT(mutex_owned(&amap->am_l));
1382 KASSERT(mutex_owned(&anon->an_lock));
1383 KASSERT(mutex_owned(&oanon->an_lock));
1384
1385 /*
1386 * now map the page in.
1387 */
1388
1389 UVMHIST_LOG(maphist, " MAPPING: anon: pm=0x%x, va=0x%x, pg=0x%x",
1390 ufi.orig_map->pmap, ufi.orig_rvaddr, pg, 0);
1391 if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg),
1392 enter_prot, access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0))
1393 != 0) {
1394
1395 /*
1396 * No need to undo what we did; we can simply think of
1397 * this as the pmap throwing away the mapping information.
1398 *
1399 * We do, however, have to go through the ReFault path,
1400 * as the map may change while we're asleep.
1401 */
1402
1403 if (anon != oanon)
1404 mutex_exit(&anon->an_lock);
1405 uvmfault_unlockall(&ufi, amap, uobj, oanon);
1406 if (!uvm_reclaimable()) {
1407 UVMHIST_LOG(maphist,
1408 "<- failed. out of VM",0,0,0,0);
1409 /* XXX instrumentation */
1410 error = ENOMEM;
1411 goto done;
1412 }
1413 /* XXX instrumentation */
1414 uvm_wait("flt_pmfail1");
1415 goto ReFault;
1416 }
1417
1418 /*
1419 * ... update the page queues.
1420 */
1421
1422 mutex_enter(&uvm_pageqlock);
1423 if (wire_fault) {
1424 uvm_pagewire(pg);
1425
1426 /*
1427 * since the now-wired page cannot be paged out,
1428 * release its swap resources for others to use.
1429 * since an anon with no swap cannot be PG_CLEAN,
1430 * clear its clean flag now.
1431 */
1432
1433 pg->flags &= ~(PG_CLEAN);
1434 uvm_anon_dropswap(anon);
1435 } else {
1436 uvm_pageactivate(pg);
1437 }
1438 mutex_exit(&uvm_pageqlock);
1439
1440 /*
1441 * done case 1! finish up by unlocking everything and returning success
1442 */
1443
1444 if (anon != oanon) {
1445 mutex_exit(&anon->an_lock);
1446 }
1447 pmap_update(ufi.orig_map->pmap);
1448 uvmfault_unlockall(&ufi, amap, uobj, oanon);
1449 error = 0;
1450 goto done;
1451
1452 Case2:
1453 /*
1454 * handle case 2: faulting on backing object or zero fill
1455 */
1456
1457 /*
1458 * locked:
1459 * maps(read), amap(if there), uobj(if !null), uobjpage(if !null)
1460 */
1461 KASSERT(amap == NULL || mutex_owned(&amap->am_l));
1462 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock));
1463 KASSERT(uobjpage == NULL || (uobjpage->flags & PG_BUSY) != 0);
1464
1465 /*
1466 * note that uobjpage can not be PGO_DONTCARE at this point. we now
1467 * set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we
1468 * have a backing object, check and see if we are going to promote
1469 * the data up to an anon during the fault.
1470 */
1471
1472 if (uobj == NULL) {
1473 uobjpage = PGO_DONTCARE;
1474 promote = true; /* always need anon here */
1475 } else {
1476 KASSERT(uobjpage != PGO_DONTCARE);
1477 promote = cow_now && UVM_ET_ISCOPYONWRITE(ufi.entry);
1478 }
1479 UVMHIST_LOG(maphist, " case 2 fault: promote=%d, zfill=%d",
1480 promote, (uobj == NULL), 0,0);
1481
1482 /*
1483 * if uobjpage is not null then we do not need to do I/O to get the
1484 * uobjpage.
1485 *
1486 * if uobjpage is null, then we need to unlock and ask the pager to
1487 * get the data for us. once we have the data, we need to reverify
1488 * the state the world. we are currently not holding any resources.
1489 */
1490
1491 if (uobjpage) {
1492 /* update rusage counters */
1493 curlwp->l_ru.ru_minflt++;
1494 } else {
1495 /* update rusage counters */
1496 curlwp->l_ru.ru_majflt++;
1497
1498 /* locked: maps(read), amap(if there), uobj */
1499 uvmfault_unlockall(&ufi, amap, NULL, NULL);
1500 /* locked: uobj */
1501
1502 uvmexp.fltget++;
1503 gotpages = 1;
1504 uoff = (ufi.orig_rvaddr - ufi.entry->start) + ufi.entry->offset;
1505 error = uobj->pgops->pgo_get(uobj, uoff, &uobjpage, &gotpages,
1506 0, access_type & MASK(ufi.entry), ufi.entry->advice,
1507 PGO_SYNCIO);
1508 /* locked: uobjpage(if no error) */
1509 KASSERT(error != 0 || (uobjpage->flags & PG_BUSY) != 0);
1510
1511 /*
1512 * recover from I/O
1513 */
1514
1515 if (error) {
1516 if (error == EAGAIN) {
1517 UVMHIST_LOG(maphist,
1518 " pgo_get says TRY AGAIN!",0,0,0,0);
1519 tsleep(&lbolt, PVM, "fltagain2", 0);
1520 goto ReFault;
1521 }
1522
1523 UVMHIST_LOG(maphist, "<- pgo_get failed (code %d)",
1524 error, 0,0,0);
1525 goto done;
1526 }
1527
1528 /* locked: uobjpage */
1529
1530 mutex_enter(&uvm_pageqlock);
1531 uvm_pageactivate(uobjpage);
1532 mutex_exit(&uvm_pageqlock);
1533
1534 /*
1535 * re-verify the state of the world by first trying to relock
1536 * the maps. always relock the object.
1537 */
1538
1539 locked = uvmfault_relock(&ufi);
1540 if (locked && amap)
1541 amap_lock(amap);
1542 uobj = uobjpage->uobject;
1543 mutex_enter(&uobj->vmobjlock);
1544
1545 /* locked(locked): maps(read), amap(if !null), uobj, uobjpage */
1546 /* locked(!locked): uobj, uobjpage */
1547
1548 /*
1549 * verify that the page has not be released and re-verify
1550 * that amap slot is still free. if there is a problem,
1551 * we unlock and clean up.
1552 */
1553
1554 if ((uobjpage->flags & PG_RELEASED) != 0 ||
1555 (locked && amap &&
1556 amap_lookup(&ufi.entry->aref,
1557 ufi.orig_rvaddr - ufi.entry->start))) {
1558 if (locked)
1559 uvmfault_unlockall(&ufi, amap, NULL, NULL);
1560 locked = false;
1561 }
1562
1563 /*
1564 * didn't get the lock? release the page and retry.
1565 */
1566
1567 if (locked == false) {
1568 UVMHIST_LOG(maphist,
1569 " wasn't able to relock after fault: retry",
1570 0,0,0,0);
1571 if (uobjpage->flags & PG_WANTED)
1572 wakeup(uobjpage);
1573 if (uobjpage->flags & PG_RELEASED) {
1574 uvmexp.fltpgrele++;
1575 uvm_pagefree(uobjpage);
1576 goto ReFault;
1577 }
1578 uobjpage->flags &= ~(PG_BUSY|PG_WANTED);
1579 UVM_PAGE_OWN(uobjpage, NULL);
1580 mutex_exit(&uobj->vmobjlock);
1581 goto ReFault;
1582 }
1583
1584 /*
1585 * we have the data in uobjpage which is busy and
1586 * not released. we are holding object lock (so the page
1587 * can't be released on us).
1588 */
1589
1590 /* locked: maps(read), amap(if !null), uobj, uobjpage */
1591 }
1592
1593 /*
1594 * locked:
1595 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj)
1596 */
1597 KASSERT(amap == NULL || mutex_owned(&amap->am_l));
1598 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock));
1599 KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0);
1600
1601 /*
1602 * notes:
1603 * - at this point uobjpage can not be NULL
1604 * - at this point uobjpage can not be PG_RELEASED (since we checked
1605 * for it above)
1606 * - at this point uobjpage could be PG_WANTED (handle later)
1607 */
1608
1609 KASSERT(uobj == NULL || uobj == uobjpage->uobject);
1610 KASSERT(uobj == NULL || !UVM_OBJ_IS_CLEAN(uobjpage->uobject) ||
1611 (uobjpage->flags & PG_CLEAN) != 0);
1612 if (promote == false) {
1613
1614 /*
1615 * we are not promoting. if the mapping is COW ensure that we
1616 * don't give more access than we should (e.g. when doing a read
1617 * fault on a COPYONWRITE mapping we want to map the COW page in
1618 * R/O even though the entry protection could be R/W).
1619 *
1620 * set "pg" to the page we want to map in (uobjpage, usually)
1621 */
1622
1623 /* no anon in this case. */
1624 anon = NULL;
1625
1626 uvmexp.flt_obj++;
1627 if (UVM_ET_ISCOPYONWRITE(ufi.entry) ||
1628 UVM_OBJ_NEEDS_WRITEFAULT(uobjpage->uobject))
1629 enter_prot &= ~VM_PROT_WRITE;
1630 pg = uobjpage; /* map in the actual object */
1631
1632 KASSERT(uobjpage != PGO_DONTCARE);
1633
1634 /*
1635 * we are faulting directly on the page. be careful
1636 * about writing to loaned pages...
1637 */
1638
1639 if (uobjpage->loan_count) {
1640 if (!cow_now) {
1641 /* read fault: cap the protection at readonly */
1642 /* cap! */
1643 enter_prot = enter_prot & ~VM_PROT_WRITE;
1644 } else {
1645 /* write fault: must break the loan here */
1646
1647 pg = uvm_loanbreak(uobjpage);
1648 if (pg == NULL) {
1649
1650 /*
1651 * drop ownership of page, it can't
1652 * be released
1653 */
1654
1655 if (uobjpage->flags & PG_WANTED)
1656 wakeup(uobjpage);
1657 uobjpage->flags &= ~(PG_BUSY|PG_WANTED);
1658 UVM_PAGE_OWN(uobjpage, NULL);
1659
1660 uvmfault_unlockall(&ufi, amap, uobj,
1661 NULL);
1662 UVMHIST_LOG(maphist,
1663 " out of RAM breaking loan, waiting",
1664 0,0,0,0);
1665 uvmexp.fltnoram++;
1666 uvm_wait("flt_noram4");
1667 goto ReFault;
1668 }
1669 uobjpage = pg;
1670 }
1671 }
1672 } else {
1673
1674 /*
1675 * if we are going to promote the data to an anon we
1676 * allocate a blank anon here and plug it into our amap.
1677 */
1678 #if DIAGNOSTIC
1679 if (amap == NULL)
1680 panic("uvm_fault: want to promote data, but no anon");
1681 #endif
1682 error = uvmfault_promote(&ufi, NULL, uobjpage,
1683 &anon, &anon_spare);
1684 switch (error) {
1685 case 0:
1686 break;
1687 case ERESTART:
1688 goto ReFault;
1689 default:
1690 goto done;
1691 }
1692
1693 pg = anon->an_page;
1694
1695 /*
1696 * fill in the data
1697 */
1698
1699 if (uobjpage != PGO_DONTCARE) {
1700 uvmexp.flt_prcopy++;
1701
1702 /*
1703 * promote to shared amap? make sure all sharing
1704 * procs see it
1705 */
1706
1707 if ((amap_flags(amap) & AMAP_SHARED) != 0) {
1708 pmap_page_protect(uobjpage, VM_PROT_NONE);
1709 /*
1710 * XXX: PAGE MIGHT BE WIRED!
1711 */
1712 }
1713
1714 /*
1715 * dispose of uobjpage. it can't be PG_RELEASED
1716 * since we still hold the object lock.
1717 * drop handle to uobj as well.
1718 */
1719
1720 if (uobjpage->flags & PG_WANTED)
1721 /* still have the obj lock */
1722 wakeup(uobjpage);
1723 uobjpage->flags &= ~(PG_BUSY|PG_WANTED);
1724 UVM_PAGE_OWN(uobjpage, NULL);
1725 mutex_exit(&uobj->vmobjlock);
1726 uobj = NULL;
1727
1728 UVMHIST_LOG(maphist,
1729 " promote uobjpage 0x%x to anon/page 0x%x/0x%x",
1730 uobjpage, anon, pg, 0);
1731
1732 } else {
1733 uvmexp.flt_przero++;
1734
1735 /*
1736 * Page is zero'd and marked dirty by
1737 * uvmfault_promote().
1738 */
1739
1740 UVMHIST_LOG(maphist," zero fill anon/page 0x%x/0%x",
1741 anon, pg, 0, 0);
1742 }
1743 }
1744
1745 /*
1746 * locked:
1747 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj),
1748 * anon(if !null), pg(if anon)
1749 *
1750 * note: pg is either the uobjpage or the new page in the new anon
1751 */
1752 KASSERT(amap == NULL || mutex_owned(&amap->am_l));
1753 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock));
1754 KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0);
1755 KASSERT(anon == NULL || mutex_owned(&anon->an_lock));
1756 KASSERT((pg->flags & PG_BUSY) != 0);
1757
1758 /*
1759 * all resources are present. we can now map it in and free our
1760 * resources.
1761 */
1762
1763 UVMHIST_LOG(maphist,
1764 " MAPPING: case2: pm=0x%x, va=0x%x, pg=0x%x, promote=%d",
1765 ufi.orig_map->pmap, ufi.orig_rvaddr, pg, promote);
1766 KASSERT((access_type & VM_PROT_WRITE) == 0 ||
1767 (pg->flags & PG_RDONLY) == 0);
1768 if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg),
1769 pg->flags & PG_RDONLY ? enter_prot & ~VM_PROT_WRITE : enter_prot,
1770 access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0)) != 0) {
1771
1772 /*
1773 * No need to undo what we did; we can simply think of
1774 * this as the pmap throwing away the mapping information.
1775 *
1776 * We do, however, have to go through the ReFault path,
1777 * as the map may change while we're asleep.
1778 */
1779
1780 if (pg->flags & PG_WANTED)
1781 wakeup(pg);
1782
1783 /*
1784 * note that pg can't be PG_RELEASED since we did not drop
1785 * the object lock since the last time we checked.
1786 */
1787 KASSERT((pg->flags & PG_RELEASED) == 0);
1788
1789 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED);
1790 UVM_PAGE_OWN(pg, NULL);
1791 uvmfault_unlockall(&ufi, amap, uobj, anon);
1792 if (!uvm_reclaimable()) {
1793 UVMHIST_LOG(maphist,
1794 "<- failed. out of VM",0,0,0,0);
1795 /* XXX instrumentation */
1796 error = ENOMEM;
1797 goto done;
1798 }
1799 /* XXX instrumentation */
1800 uvm_wait("flt_pmfail2");
1801 goto ReFault;
1802 }
1803
1804 mutex_enter(&uvm_pageqlock);
1805 if (wire_fault) {
1806 uvm_pagewire(pg);
1807 if (pg->pqflags & PQ_AOBJ) {
1808
1809 /*
1810 * since the now-wired page cannot be paged out,
1811 * release its swap resources for others to use.
1812 * since an aobj page with no swap cannot be PG_CLEAN,
1813 * clear its clean flag now.
1814 */
1815
1816 KASSERT(uobj != NULL);
1817 pg->flags &= ~(PG_CLEAN);
1818 uao_dropswap(uobj, pg->offset >> PAGE_SHIFT);
1819 }
1820 } else {
1821 uvm_pageactivate(pg);
1822 }
1823 mutex_exit(&uvm_pageqlock);
1824 if (pg->flags & PG_WANTED)
1825 wakeup(pg);
1826
1827 /*
1828 * note that pg can't be PG_RELEASED since we did not drop the object
1829 * lock since the last time we checked.
1830 */
1831 KASSERT((pg->flags & PG_RELEASED) == 0);
1832
1833 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED);
1834 UVM_PAGE_OWN(pg, NULL);
1835 pmap_update(ufi.orig_map->pmap);
1836 uvmfault_unlockall(&ufi, amap, uobj, anon);
1837 UVMHIST_LOG(maphist, "<- done (SUCCESS!)",0,0,0,0);
1838 error = 0;
1839 done:
1840 if (anon_spare != NULL) {
1841 anon_spare->an_ref--;
1842 uvm_anfree(anon_spare);
1843 }
1844 return error;
1845 }
1846
1847
1848 /*
1849 * uvm_fault_wire: wire down a range of virtual addresses in a map.
1850 *
1851 * => map may be read-locked by caller, but MUST NOT be write-locked.
1852 * => if map is read-locked, any operations which may cause map to
1853 * be write-locked in uvm_fault() must be taken care of by
1854 * the caller. See uvm_map_pageable().
1855 */
1856
1857 int
1858 uvm_fault_wire(struct vm_map *map, vaddr_t start, vaddr_t end,
1859 vm_prot_t access_type, int wiremax)
1860 {
1861 vaddr_t va;
1862 int error;
1863
1864 /*
1865 * now fault it in a page at a time. if the fault fails then we have
1866 * to undo what we have done. note that in uvm_fault VM_PROT_NONE
1867 * is replaced with the max protection if fault_type is VM_FAULT_WIRE.
1868 */
1869
1870 /*
1871 * XXX work around overflowing a vaddr_t. this prevents us from
1872 * wiring the last page in the address space, though.
1873 */
1874 if (start > end) {
1875 return EFAULT;
1876 }
1877
1878 for (va = start ; va < end ; va += PAGE_SIZE) {
1879 error = uvm_fault_internal(map, va, access_type,
1880 wiremax ? UVM_FAULT_WIREMAX : UVM_FAULT_WIRE);
1881 if (error) {
1882 if (va != start) {
1883 uvm_fault_unwire(map, start, va);
1884 }
1885 return error;
1886 }
1887 }
1888 return 0;
1889 }
1890
1891 /*
1892 * uvm_fault_unwire(): unwire range of virtual space.
1893 */
1894
1895 void
1896 uvm_fault_unwire(struct vm_map *map, vaddr_t start, vaddr_t end)
1897 {
1898 vm_map_lock_read(map);
1899 uvm_fault_unwire_locked(map, start, end);
1900 vm_map_unlock_read(map);
1901 }
1902
1903 /*
1904 * uvm_fault_unwire_locked(): the guts of uvm_fault_unwire().
1905 *
1906 * => map must be at least read-locked.
1907 */
1908
1909 void
1910 uvm_fault_unwire_locked(struct vm_map *map, vaddr_t start, vaddr_t end)
1911 {
1912 struct vm_map_entry *entry;
1913 pmap_t pmap = vm_map_pmap(map);
1914 vaddr_t va;
1915 paddr_t pa;
1916 struct vm_page *pg;
1917
1918 KASSERT((map->flags & VM_MAP_INTRSAFE) == 0);
1919
1920 /*
1921 * we assume that the area we are unwiring has actually been wired
1922 * in the first place. this means that we should be able to extract
1923 * the PAs from the pmap. we also lock out the page daemon so that
1924 * we can call uvm_pageunwire.
1925 */
1926
1927 mutex_enter(&uvm_pageqlock);
1928
1929 /*
1930 * find the beginning map entry for the region.
1931 */
1932
1933 KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map));
1934 if (uvm_map_lookup_entry(map, start, &entry) == false)
1935 panic("uvm_fault_unwire_locked: address not in map");
1936
1937 for (va = start; va < end; va += PAGE_SIZE) {
1938 if (pmap_extract(pmap, va, &pa) == false)
1939 continue;
1940
1941 /*
1942 * find the map entry for the current address.
1943 */
1944
1945 KASSERT(va >= entry->start);
1946 while (va >= entry->end) {
1947 KASSERT(entry->next != &map->header &&
1948 entry->next->start <= entry->end);
1949 entry = entry->next;
1950 }
1951
1952 /*
1953 * if the entry is no longer wired, tell the pmap.
1954 */
1955
1956 if (VM_MAPENT_ISWIRED(entry) == 0)
1957 pmap_unwire(pmap, va);
1958
1959 pg = PHYS_TO_VM_PAGE(pa);
1960 if (pg)
1961 uvm_pageunwire(pg);
1962 }
1963
1964 mutex_exit(&uvm_pageqlock);
1965 }
Cache object: e7d97a82908feef7b9c1d21e6329e7c3
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