vm_fault.c revision 266607
1/*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * 9 * 10 * This code is derived from software contributed to Berkeley by 11 * The Mach Operating System project at Carnegie-Mellon University. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94 42 * 43 * 44 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 45 * All rights reserved. 46 * 47 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 48 * 49 * Permission to use, copy, modify and distribute this software and 50 * its documentation is hereby granted, provided that both the copyright 51 * notice and this permission notice appear in all copies of the 52 * software, derivative works or modified versions, and any portions 53 * thereof, and that both notices appear in supporting documentation. 54 * 55 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 56 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 57 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 58 * 59 * Carnegie Mellon requests users of this software to return to 60 * 61 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 62 * School of Computer Science 63 * Carnegie Mellon University 64 * Pittsburgh PA 15213-3890 65 * 66 * any improvements or extensions that they make and grant Carnegie the 67 * rights to redistribute these changes. 68 */ 69 70/* 71 * Page fault handling module. 72 */ 73 74#include <sys/cdefs.h> 75__FBSDID("$FreeBSD: stable/10/sys/vm/vm_fault.c 266607 2014-05-24 09:50:10Z kib $"); 76 77#include "opt_ktrace.h" 78#include "opt_vm.h" 79 80#include <sys/param.h> 81#include <sys/systm.h> 82#include <sys/kernel.h> 83#include <sys/lock.h> 84#include <sys/proc.h> 85#include <sys/resourcevar.h> 86#include <sys/rwlock.h> 87#include <sys/sysctl.h> 88#include <sys/vmmeter.h> 89#include <sys/vnode.h> 90#ifdef KTRACE 91#include <sys/ktrace.h> 92#endif 93 94#include <vm/vm.h> 95#include <vm/vm_param.h> 96#include <vm/pmap.h> 97#include <vm/vm_map.h> 98#include <vm/vm_object.h> 99#include <vm/vm_page.h> 100#include <vm/vm_pageout.h> 101#include <vm/vm_kern.h> 102#include <vm/vm_pager.h> 103#include <vm/vm_extern.h> 104 105#define PFBAK 4 106#define PFFOR 4 107#define PAGEORDER_SIZE (PFBAK+PFFOR) 108 109static int prefault_pageorder[] = { 110 -1 * PAGE_SIZE, 1 * PAGE_SIZE, 111 -2 * PAGE_SIZE, 2 * PAGE_SIZE, 112 -3 * PAGE_SIZE, 3 * PAGE_SIZE, 113 -4 * PAGE_SIZE, 4 * PAGE_SIZE 114}; 115 116static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); 117static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t); 118 119#define VM_FAULT_READ_BEHIND 8 120#define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX) 121#define VM_FAULT_NINCR (VM_FAULT_READ_MAX / VM_FAULT_READ_BEHIND) 122#define VM_FAULT_SUM (VM_FAULT_NINCR * (VM_FAULT_NINCR + 1) / 2) 123#define VM_FAULT_CACHE_BEHIND (VM_FAULT_READ_BEHIND * VM_FAULT_SUM) 124 125struct faultstate { 126 vm_page_t m; 127 vm_object_t object; 128 vm_pindex_t pindex; 129 vm_page_t first_m; 130 vm_object_t first_object; 131 vm_pindex_t first_pindex; 132 vm_map_t map; 133 vm_map_entry_t entry; 134 int lookup_still_valid; 135 struct vnode *vp; 136}; 137 138static void vm_fault_cache_behind(const struct faultstate *fs, int distance); 139 140static inline void 141release_page(struct faultstate *fs) 142{ 143 144 vm_page_xunbusy(fs->m); 145 vm_page_lock(fs->m); 146 vm_page_deactivate(fs->m); 147 vm_page_unlock(fs->m); 148 fs->m = NULL; 149} 150 151static inline void 152unlock_map(struct faultstate *fs) 153{ 154 155 if (fs->lookup_still_valid) { 156 vm_map_lookup_done(fs->map, fs->entry); 157 fs->lookup_still_valid = FALSE; 158 } 159} 160 161static void 162unlock_and_deallocate(struct faultstate *fs) 163{ 164 165 vm_object_pip_wakeup(fs->object); 166 VM_OBJECT_WUNLOCK(fs->object); 167 if (fs->object != fs->first_object) { 168 VM_OBJECT_WLOCK(fs->first_object); 169 vm_page_lock(fs->first_m); 170 vm_page_free(fs->first_m); 171 vm_page_unlock(fs->first_m); 172 vm_object_pip_wakeup(fs->first_object); 173 VM_OBJECT_WUNLOCK(fs->first_object); 174 fs->first_m = NULL; 175 } 176 vm_object_deallocate(fs->first_object); 177 unlock_map(fs); 178 if (fs->vp != NULL) { 179 vput(fs->vp); 180 fs->vp = NULL; 181 } 182} 183 184/* 185 * TRYPAGER - used by vm_fault to calculate whether the pager for the 186 * current object *might* contain the page. 187 * 188 * default objects are zero-fill, there is no real pager. 189 */ 190#define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 191 ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 || wired)) 192 193/* 194 * vm_fault: 195 * 196 * Handle a page fault occurring at the given address, 197 * requiring the given permissions, in the map specified. 198 * If successful, the page is inserted into the 199 * associated physical map. 200 * 201 * NOTE: the given address should be truncated to the 202 * proper page address. 203 * 204 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 205 * a standard error specifying why the fault is fatal is returned. 206 * 207 * The map in question must be referenced, and remains so. 208 * Caller may hold no locks. 209 */ 210int 211vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 212 int fault_flags) 213{ 214 struct thread *td; 215 int result; 216 217 td = curthread; 218 if ((td->td_pflags & TDP_NOFAULTING) != 0) 219 return (KERN_PROTECTION_FAILURE); 220#ifdef KTRACE 221 if (map != kernel_map && KTRPOINT(td, KTR_FAULT)) 222 ktrfault(vaddr, fault_type); 223#endif 224 result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags, 225 NULL); 226#ifdef KTRACE 227 if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND)) 228 ktrfaultend(result); 229#endif 230 return (result); 231} 232 233int 234vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 235 int fault_flags, vm_page_t *m_hold) 236{ 237 vm_prot_t prot; 238 long ahead, behind; 239 int alloc_req, era, faultcount, nera, reqpage, result; 240 boolean_t growstack, is_first_object_locked, wired; 241 int map_generation; 242 vm_object_t next_object; 243 vm_page_t marray[VM_FAULT_READ_MAX]; 244 int hardfault; 245 struct faultstate fs; 246 struct vnode *vp; 247 int locked, error; 248 249 hardfault = 0; 250 growstack = TRUE; 251 PCPU_INC(cnt.v_vm_faults); 252 fs.vp = NULL; 253 faultcount = reqpage = 0; 254 255RetryFault:; 256 257 /* 258 * Find the backing store object and offset into it to begin the 259 * search. 260 */ 261 fs.map = map; 262 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 263 &fs.first_object, &fs.first_pindex, &prot, &wired); 264 if (result != KERN_SUCCESS) { 265 if (growstack && result == KERN_INVALID_ADDRESS && 266 map != kernel_map) { 267 result = vm_map_growstack(curproc, vaddr); 268 if (result != KERN_SUCCESS) 269 return (KERN_FAILURE); 270 growstack = FALSE; 271 goto RetryFault; 272 } 273 return (result); 274 } 275 276 map_generation = fs.map->timestamp; 277 278 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 279 if ((curthread->td_pflags & TDP_DEVMEMIO) != 0) { 280 vm_map_unlock_read(fs.map); 281 return (KERN_FAILURE); 282 } 283 panic("vm_fault: fault on nofault entry, addr: %lx", 284 (u_long)vaddr); 285 } 286 287 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION && 288 fs.entry->wiring_thread != curthread) { 289 vm_map_unlock_read(fs.map); 290 vm_map_lock(fs.map); 291 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) && 292 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) { 293 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP; 294 vm_map_unlock_and_wait(fs.map, 0); 295 } else 296 vm_map_unlock(fs.map); 297 goto RetryFault; 298 } 299 300 /* 301 * Make a reference to this object to prevent its disposal while we 302 * are messing with it. Once we have the reference, the map is free 303 * to be diddled. Since objects reference their shadows (and copies), 304 * they will stay around as well. 305 * 306 * Bump the paging-in-progress count to prevent size changes (e.g. 307 * truncation operations) during I/O. This must be done after 308 * obtaining the vnode lock in order to avoid possible deadlocks. 309 */ 310 VM_OBJECT_WLOCK(fs.first_object); 311 vm_object_reference_locked(fs.first_object); 312 vm_object_pip_add(fs.first_object, 1); 313 314 fs.lookup_still_valid = TRUE; 315 316 if (wired) 317 fault_type = prot | (fault_type & VM_PROT_COPY); 318 319 fs.first_m = NULL; 320 321 /* 322 * Search for the page at object/offset. 323 */ 324 fs.object = fs.first_object; 325 fs.pindex = fs.first_pindex; 326 while (TRUE) { 327 /* 328 * If the object is dead, we stop here 329 */ 330 if (fs.object->flags & OBJ_DEAD) { 331 unlock_and_deallocate(&fs); 332 return (KERN_PROTECTION_FAILURE); 333 } 334 335 /* 336 * See if page is resident 337 */ 338 fs.m = vm_page_lookup(fs.object, fs.pindex); 339 if (fs.m != NULL) { 340 /* 341 * Wait/Retry if the page is busy. We have to do this 342 * if the page is either exclusive or shared busy 343 * because the vm_pager may be using read busy for 344 * pageouts (and even pageins if it is the vnode 345 * pager), and we could end up trying to pagein and 346 * pageout the same page simultaneously. 347 * 348 * We can theoretically allow the busy case on a read 349 * fault if the page is marked valid, but since such 350 * pages are typically already pmap'd, putting that 351 * special case in might be more effort then it is 352 * worth. We cannot under any circumstances mess 353 * around with a shared busied page except, perhaps, 354 * to pmap it. 355 */ 356 if (vm_page_busied(fs.m)) { 357 /* 358 * Reference the page before unlocking and 359 * sleeping so that the page daemon is less 360 * likely to reclaim it. 361 */ 362 vm_page_aflag_set(fs.m, PGA_REFERENCED); 363 if (fs.object != fs.first_object) { 364 if (!VM_OBJECT_TRYWLOCK( 365 fs.first_object)) { 366 VM_OBJECT_WUNLOCK(fs.object); 367 VM_OBJECT_WLOCK(fs.first_object); 368 VM_OBJECT_WLOCK(fs.object); 369 } 370 vm_page_lock(fs.first_m); 371 vm_page_free(fs.first_m); 372 vm_page_unlock(fs.first_m); 373 vm_object_pip_wakeup(fs.first_object); 374 VM_OBJECT_WUNLOCK(fs.first_object); 375 fs.first_m = NULL; 376 } 377 unlock_map(&fs); 378 if (fs.m == vm_page_lookup(fs.object, 379 fs.pindex)) { 380 vm_page_sleep_if_busy(fs.m, "vmpfw"); 381 } 382 vm_object_pip_wakeup(fs.object); 383 VM_OBJECT_WUNLOCK(fs.object); 384 PCPU_INC(cnt.v_intrans); 385 vm_object_deallocate(fs.first_object); 386 goto RetryFault; 387 } 388 vm_page_lock(fs.m); 389 vm_page_remque(fs.m); 390 vm_page_unlock(fs.m); 391 392 /* 393 * Mark page busy for other processes, and the 394 * pagedaemon. If it still isn't completely valid 395 * (readable), jump to readrest, else break-out ( we 396 * found the page ). 397 */ 398 vm_page_xbusy(fs.m); 399 if (fs.m->valid != VM_PAGE_BITS_ALL) 400 goto readrest; 401 break; 402 } 403 404 /* 405 * Page is not resident, If this is the search termination 406 * or the pager might contain the page, allocate a new page. 407 */ 408 if (TRYPAGER || fs.object == fs.first_object) { 409 if (fs.pindex >= fs.object->size) { 410 unlock_and_deallocate(&fs); 411 return (KERN_PROTECTION_FAILURE); 412 } 413 414 /* 415 * Allocate a new page for this object/offset pair. 416 * 417 * Unlocked read of the p_flag is harmless. At 418 * worst, the P_KILLED might be not observed 419 * there, and allocation can fail, causing 420 * restart and new reading of the p_flag. 421 */ 422 fs.m = NULL; 423 if (!vm_page_count_severe() || P_KILLED(curproc)) { 424#if VM_NRESERVLEVEL > 0 425 if ((fs.object->flags & OBJ_COLORED) == 0) { 426 fs.object->flags |= OBJ_COLORED; 427 fs.object->pg_color = atop(vaddr) - 428 fs.pindex; 429 } 430#endif 431 alloc_req = P_KILLED(curproc) ? 432 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 433 if (fs.object->type != OBJT_VNODE && 434 fs.object->backing_object == NULL) 435 alloc_req |= VM_ALLOC_ZERO; 436 fs.m = vm_page_alloc(fs.object, fs.pindex, 437 alloc_req); 438 } 439 if (fs.m == NULL) { 440 unlock_and_deallocate(&fs); 441 VM_WAITPFAULT; 442 goto RetryFault; 443 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 444 break; 445 } 446 447readrest: 448 /* 449 * We have found a valid page or we have allocated a new page. 450 * The page thus may not be valid or may not be entirely 451 * valid. 452 * 453 * Attempt to fault-in the page if there is a chance that the 454 * pager has it, and potentially fault in additional pages 455 * at the same time. 456 */ 457 if (TRYPAGER) { 458 int rv; 459 u_char behavior = vm_map_entry_behavior(fs.entry); 460 461 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 462 P_KILLED(curproc)) { 463 behind = 0; 464 ahead = 0; 465 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) { 466 behind = 0; 467 ahead = atop(fs.entry->end - vaddr) - 1; 468 if (ahead > VM_FAULT_READ_AHEAD_MAX) 469 ahead = VM_FAULT_READ_AHEAD_MAX; 470 if (fs.pindex == fs.entry->next_read) 471 vm_fault_cache_behind(&fs, 472 VM_FAULT_READ_MAX); 473 } else { 474 /* 475 * If this is a sequential page fault, then 476 * arithmetically increase the number of pages 477 * in the read-ahead window. Otherwise, reset 478 * the read-ahead window to its smallest size. 479 */ 480 behind = atop(vaddr - fs.entry->start); 481 if (behind > VM_FAULT_READ_BEHIND) 482 behind = VM_FAULT_READ_BEHIND; 483 ahead = atop(fs.entry->end - vaddr) - 1; 484 era = fs.entry->read_ahead; 485 if (fs.pindex == fs.entry->next_read) { 486 nera = era + behind; 487 if (nera > VM_FAULT_READ_AHEAD_MAX) 488 nera = VM_FAULT_READ_AHEAD_MAX; 489 behind = 0; 490 if (ahead > nera) 491 ahead = nera; 492 if (era == VM_FAULT_READ_AHEAD_MAX) 493 vm_fault_cache_behind(&fs, 494 VM_FAULT_CACHE_BEHIND); 495 } else if (ahead > VM_FAULT_READ_AHEAD_MIN) 496 ahead = VM_FAULT_READ_AHEAD_MIN; 497 if (era != ahead) 498 fs.entry->read_ahead = ahead; 499 } 500 501 /* 502 * Call the pager to retrieve the data, if any, after 503 * releasing the lock on the map. We hold a ref on 504 * fs.object and the pages are exclusive busied. 505 */ 506 unlock_map(&fs); 507 508 if (fs.object->type == OBJT_VNODE) { 509 vp = fs.object->handle; 510 if (vp == fs.vp) 511 goto vnode_locked; 512 else if (fs.vp != NULL) { 513 vput(fs.vp); 514 fs.vp = NULL; 515 } 516 locked = VOP_ISLOCKED(vp); 517 518 if (locked != LK_EXCLUSIVE) 519 locked = LK_SHARED; 520 /* Do not sleep for vnode lock while fs.m is busy */ 521 error = vget(vp, locked | LK_CANRECURSE | 522 LK_NOWAIT, curthread); 523 if (error != 0) { 524 vhold(vp); 525 release_page(&fs); 526 unlock_and_deallocate(&fs); 527 error = vget(vp, locked | LK_RETRY | 528 LK_CANRECURSE, curthread); 529 vdrop(vp); 530 fs.vp = vp; 531 KASSERT(error == 0, 532 ("vm_fault: vget failed")); 533 goto RetryFault; 534 } 535 fs.vp = vp; 536 } 537vnode_locked: 538 KASSERT(fs.vp == NULL || !fs.map->system_map, 539 ("vm_fault: vnode-backed object mapped by system map")); 540 541 /* 542 * now we find out if any other pages should be paged 543 * in at this time this routine checks to see if the 544 * pages surrounding this fault reside in the same 545 * object as the page for this fault. If they do, 546 * then they are faulted in also into the object. The 547 * array "marray" returned contains an array of 548 * vm_page_t structs where one of them is the 549 * vm_page_t passed to the routine. The reqpage 550 * return value is the index into the marray for the 551 * vm_page_t passed to the routine. 552 * 553 * fs.m plus the additional pages are exclusive busied. 554 */ 555 faultcount = vm_fault_additional_pages( 556 fs.m, behind, ahead, marray, &reqpage); 557 558 rv = faultcount ? 559 vm_pager_get_pages(fs.object, marray, faultcount, 560 reqpage) : VM_PAGER_FAIL; 561 562 if (rv == VM_PAGER_OK) { 563 /* 564 * Found the page. Leave it busy while we play 565 * with it. 566 */ 567 568 /* 569 * Relookup in case pager changed page. Pager 570 * is responsible for disposition of old page 571 * if moved. 572 */ 573 fs.m = vm_page_lookup(fs.object, fs.pindex); 574 if (!fs.m) { 575 unlock_and_deallocate(&fs); 576 goto RetryFault; 577 } 578 579 hardfault++; 580 break; /* break to PAGE HAS BEEN FOUND */ 581 } 582 /* 583 * Remove the bogus page (which does not exist at this 584 * object/offset); before doing so, we must get back 585 * our object lock to preserve our invariant. 586 * 587 * Also wake up any other process that may want to bring 588 * in this page. 589 * 590 * If this is the top-level object, we must leave the 591 * busy page to prevent another process from rushing 592 * past us, and inserting the page in that object at 593 * the same time that we are. 594 */ 595 if (rv == VM_PAGER_ERROR) 596 printf("vm_fault: pager read error, pid %d (%s)\n", 597 curproc->p_pid, curproc->p_comm); 598 /* 599 * Data outside the range of the pager or an I/O error 600 */ 601 /* 602 * XXX - the check for kernel_map is a kludge to work 603 * around having the machine panic on a kernel space 604 * fault w/ I/O error. 605 */ 606 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 607 (rv == VM_PAGER_BAD)) { 608 vm_page_lock(fs.m); 609 vm_page_free(fs.m); 610 vm_page_unlock(fs.m); 611 fs.m = NULL; 612 unlock_and_deallocate(&fs); 613 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 614 } 615 if (fs.object != fs.first_object) { 616 vm_page_lock(fs.m); 617 vm_page_free(fs.m); 618 vm_page_unlock(fs.m); 619 fs.m = NULL; 620 /* 621 * XXX - we cannot just fall out at this 622 * point, m has been freed and is invalid! 623 */ 624 } 625 } 626 627 /* 628 * We get here if the object has default pager (or unwiring) 629 * or the pager doesn't have the page. 630 */ 631 if (fs.object == fs.first_object) 632 fs.first_m = fs.m; 633 634 /* 635 * Move on to the next object. Lock the next object before 636 * unlocking the current one. 637 */ 638 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 639 next_object = fs.object->backing_object; 640 if (next_object == NULL) { 641 /* 642 * If there's no object left, fill the page in the top 643 * object with zeros. 644 */ 645 if (fs.object != fs.first_object) { 646 vm_object_pip_wakeup(fs.object); 647 VM_OBJECT_WUNLOCK(fs.object); 648 649 fs.object = fs.first_object; 650 fs.pindex = fs.first_pindex; 651 fs.m = fs.first_m; 652 VM_OBJECT_WLOCK(fs.object); 653 } 654 fs.first_m = NULL; 655 656 /* 657 * Zero the page if necessary and mark it valid. 658 */ 659 if ((fs.m->flags & PG_ZERO) == 0) { 660 pmap_zero_page(fs.m); 661 } else { 662 PCPU_INC(cnt.v_ozfod); 663 } 664 PCPU_INC(cnt.v_zfod); 665 fs.m->valid = VM_PAGE_BITS_ALL; 666 break; /* break to PAGE HAS BEEN FOUND */ 667 } else { 668 KASSERT(fs.object != next_object, 669 ("object loop %p", next_object)); 670 VM_OBJECT_WLOCK(next_object); 671 vm_object_pip_add(next_object, 1); 672 if (fs.object != fs.first_object) 673 vm_object_pip_wakeup(fs.object); 674 VM_OBJECT_WUNLOCK(fs.object); 675 fs.object = next_object; 676 } 677 } 678 679 vm_page_assert_xbusied(fs.m); 680 681 /* 682 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 683 * is held.] 684 */ 685 686 /* 687 * If the page is being written, but isn't already owned by the 688 * top-level object, we have to copy it into a new page owned by the 689 * top-level object. 690 */ 691 if (fs.object != fs.first_object) { 692 /* 693 * We only really need to copy if we want to write it. 694 */ 695 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 696 /* 697 * This allows pages to be virtually copied from a 698 * backing_object into the first_object, where the 699 * backing object has no other refs to it, and cannot 700 * gain any more refs. Instead of a bcopy, we just 701 * move the page from the backing object to the 702 * first object. Note that we must mark the page 703 * dirty in the first object so that it will go out 704 * to swap when needed. 705 */ 706 is_first_object_locked = FALSE; 707 if ( 708 /* 709 * Only one shadow object 710 */ 711 (fs.object->shadow_count == 1) && 712 /* 713 * No COW refs, except us 714 */ 715 (fs.object->ref_count == 1) && 716 /* 717 * No one else can look this object up 718 */ 719 (fs.object->handle == NULL) && 720 /* 721 * No other ways to look the object up 722 */ 723 ((fs.object->type == OBJT_DEFAULT) || 724 (fs.object->type == OBJT_SWAP)) && 725 (is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) && 726 /* 727 * We don't chase down the shadow chain 728 */ 729 fs.object == fs.first_object->backing_object) { 730 /* 731 * get rid of the unnecessary page 732 */ 733 vm_page_lock(fs.first_m); 734 vm_page_free(fs.first_m); 735 vm_page_unlock(fs.first_m); 736 /* 737 * grab the page and put it into the 738 * process'es object. The page is 739 * automatically made dirty. 740 */ 741 if (vm_page_rename(fs.m, fs.first_object, 742 fs.first_pindex)) { 743 unlock_and_deallocate(&fs); 744 goto RetryFault; 745 } 746 vm_page_xbusy(fs.m); 747 fs.first_m = fs.m; 748 fs.m = NULL; 749 PCPU_INC(cnt.v_cow_optim); 750 } else { 751 /* 752 * Oh, well, lets copy it. 753 */ 754 pmap_copy_page(fs.m, fs.first_m); 755 fs.first_m->valid = VM_PAGE_BITS_ALL; 756 if (wired && (fault_flags & 757 VM_FAULT_CHANGE_WIRING) == 0) { 758 vm_page_lock(fs.first_m); 759 vm_page_wire(fs.first_m); 760 vm_page_unlock(fs.first_m); 761 762 vm_page_lock(fs.m); 763 vm_page_unwire(fs.m, FALSE); 764 vm_page_unlock(fs.m); 765 } 766 /* 767 * We no longer need the old page or object. 768 */ 769 release_page(&fs); 770 } 771 /* 772 * fs.object != fs.first_object due to above 773 * conditional 774 */ 775 vm_object_pip_wakeup(fs.object); 776 VM_OBJECT_WUNLOCK(fs.object); 777 /* 778 * Only use the new page below... 779 */ 780 fs.object = fs.first_object; 781 fs.pindex = fs.first_pindex; 782 fs.m = fs.first_m; 783 if (!is_first_object_locked) 784 VM_OBJECT_WLOCK(fs.object); 785 PCPU_INC(cnt.v_cow_faults); 786 curthread->td_cow++; 787 } else { 788 prot &= ~VM_PROT_WRITE; 789 } 790 } 791 792 /* 793 * We must verify that the maps have not changed since our last 794 * lookup. 795 */ 796 if (!fs.lookup_still_valid) { 797 vm_object_t retry_object; 798 vm_pindex_t retry_pindex; 799 vm_prot_t retry_prot; 800 801 if (!vm_map_trylock_read(fs.map)) { 802 release_page(&fs); 803 unlock_and_deallocate(&fs); 804 goto RetryFault; 805 } 806 fs.lookup_still_valid = TRUE; 807 if (fs.map->timestamp != map_generation) { 808 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 809 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 810 811 /* 812 * If we don't need the page any longer, put it on the inactive 813 * list (the easiest thing to do here). If no one needs it, 814 * pageout will grab it eventually. 815 */ 816 if (result != KERN_SUCCESS) { 817 release_page(&fs); 818 unlock_and_deallocate(&fs); 819 820 /* 821 * If retry of map lookup would have blocked then 822 * retry fault from start. 823 */ 824 if (result == KERN_FAILURE) 825 goto RetryFault; 826 return (result); 827 } 828 if ((retry_object != fs.first_object) || 829 (retry_pindex != fs.first_pindex)) { 830 release_page(&fs); 831 unlock_and_deallocate(&fs); 832 goto RetryFault; 833 } 834 835 /* 836 * Check whether the protection has changed or the object has 837 * been copied while we left the map unlocked. Changing from 838 * read to write permission is OK - we leave the page 839 * write-protected, and catch the write fault. Changing from 840 * write to read permission means that we can't mark the page 841 * write-enabled after all. 842 */ 843 prot &= retry_prot; 844 } 845 } 846 /* 847 * If the page was filled by a pager, update the map entry's 848 * last read offset. Since the pager does not return the 849 * actual set of pages that it read, this update is based on 850 * the requested set. Typically, the requested and actual 851 * sets are the same. 852 * 853 * XXX The following assignment modifies the map 854 * without holding a write lock on it. 855 */ 856 if (hardfault) 857 fs.entry->next_read = fs.pindex + faultcount - reqpage; 858 859 if ((prot & VM_PROT_WRITE) != 0 || 860 (fault_flags & VM_FAULT_DIRTY) != 0) { 861 vm_object_set_writeable_dirty(fs.object); 862 863 /* 864 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 865 * if the page is already dirty to prevent data written with 866 * the expectation of being synced from not being synced. 867 * Likewise if this entry does not request NOSYNC then make 868 * sure the page isn't marked NOSYNC. Applications sharing 869 * data should use the same flags to avoid ping ponging. 870 */ 871 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 872 if (fs.m->dirty == 0) 873 fs.m->oflags |= VPO_NOSYNC; 874 } else { 875 fs.m->oflags &= ~VPO_NOSYNC; 876 } 877 878 /* 879 * If the fault is a write, we know that this page is being 880 * written NOW so dirty it explicitly to save on 881 * pmap_is_modified() calls later. 882 * 883 * Also tell the backing pager, if any, that it should remove 884 * any swap backing since the page is now dirty. 885 */ 886 if (((fault_type & VM_PROT_WRITE) != 0 && 887 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) || 888 (fault_flags & VM_FAULT_DIRTY) != 0) { 889 vm_page_dirty(fs.m); 890 vm_pager_page_unswapped(fs.m); 891 } 892 } 893 894 vm_page_assert_xbusied(fs.m); 895 896 /* 897 * Page must be completely valid or it is not fit to 898 * map into user space. vm_pager_get_pages() ensures this. 899 */ 900 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 901 ("vm_fault: page %p partially invalid", fs.m)); 902 VM_OBJECT_WUNLOCK(fs.object); 903 904 /* 905 * Put this page into the physical map. We had to do the unlock above 906 * because pmap_enter() may sleep. We don't put the page 907 * back on the active queue until later so that the pageout daemon 908 * won't find it (yet). 909 */ 910 pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired); 911 if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0) 912 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); 913 VM_OBJECT_WLOCK(fs.object); 914 vm_page_lock(fs.m); 915 916 /* 917 * If the page is not wired down, then put it where the pageout daemon 918 * can find it. 919 */ 920 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 921 if (wired) 922 vm_page_wire(fs.m); 923 else 924 vm_page_unwire(fs.m, 1); 925 } else 926 vm_page_activate(fs.m); 927 if (m_hold != NULL) { 928 *m_hold = fs.m; 929 vm_page_hold(fs.m); 930 } 931 vm_page_unlock(fs.m); 932 vm_page_xunbusy(fs.m); 933 934 /* 935 * Unlock everything, and return 936 */ 937 unlock_and_deallocate(&fs); 938 if (hardfault) { 939 PCPU_INC(cnt.v_io_faults); 940 curthread->td_ru.ru_majflt++; 941 } else 942 curthread->td_ru.ru_minflt++; 943 944 return (KERN_SUCCESS); 945} 946 947/* 948 * Speed up the reclamation of up to "distance" pages that precede the 949 * faulting pindex within the first object of the shadow chain. 950 */ 951static void 952vm_fault_cache_behind(const struct faultstate *fs, int distance) 953{ 954 vm_object_t first_object, object; 955 vm_page_t m, m_prev; 956 vm_pindex_t pindex; 957 958 object = fs->object; 959 VM_OBJECT_ASSERT_WLOCKED(object); 960 first_object = fs->first_object; 961 if (first_object != object) { 962 if (!VM_OBJECT_TRYWLOCK(first_object)) { 963 VM_OBJECT_WUNLOCK(object); 964 VM_OBJECT_WLOCK(first_object); 965 VM_OBJECT_WLOCK(object); 966 } 967 } 968 /* Neither fictitious nor unmanaged pages can be cached. */ 969 if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) { 970 if (fs->first_pindex < distance) 971 pindex = 0; 972 else 973 pindex = fs->first_pindex - distance; 974 if (pindex < OFF_TO_IDX(fs->entry->offset)) 975 pindex = OFF_TO_IDX(fs->entry->offset); 976 m = first_object != object ? fs->first_m : fs->m; 977 vm_page_assert_xbusied(m); 978 m_prev = vm_page_prev(m); 979 while ((m = m_prev) != NULL && m->pindex >= pindex && 980 m->valid == VM_PAGE_BITS_ALL) { 981 m_prev = vm_page_prev(m); 982 if (vm_page_busied(m)) 983 continue; 984 vm_page_lock(m); 985 if (m->hold_count == 0 && m->wire_count == 0) { 986 pmap_remove_all(m); 987 vm_page_aflag_clear(m, PGA_REFERENCED); 988 if (m->dirty != 0) 989 vm_page_deactivate(m); 990 else 991 vm_page_cache(m); 992 } 993 vm_page_unlock(m); 994 } 995 } 996 if (first_object != object) 997 VM_OBJECT_WUNLOCK(first_object); 998} 999 1000/* 1001 * vm_fault_prefault provides a quick way of clustering 1002 * pagefaults into a processes address space. It is a "cousin" 1003 * of vm_map_pmap_enter, except it runs at page fault time instead 1004 * of mmap time. 1005 */ 1006static void 1007vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) 1008{ 1009 int i; 1010 vm_offset_t addr, starta; 1011 vm_pindex_t pindex; 1012 vm_page_t m; 1013 vm_object_t object; 1014 1015 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 1016 return; 1017 1018 object = entry->object.vm_object; 1019 1020 starta = addra - PFBAK * PAGE_SIZE; 1021 if (starta < entry->start) { 1022 starta = entry->start; 1023 } else if (starta > addra) { 1024 starta = 0; 1025 } 1026 1027 for (i = 0; i < PAGEORDER_SIZE; i++) { 1028 vm_object_t backing_object, lobject; 1029 1030 addr = addra + prefault_pageorder[i]; 1031 if (addr > addra + (PFFOR * PAGE_SIZE)) 1032 addr = 0; 1033 1034 if (addr < starta || addr >= entry->end) 1035 continue; 1036 1037 if (!pmap_is_prefaultable(pmap, addr)) 1038 continue; 1039 1040 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1041 lobject = object; 1042 VM_OBJECT_RLOCK(lobject); 1043 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1044 lobject->type == OBJT_DEFAULT && 1045 (backing_object = lobject->backing_object) != NULL) { 1046 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1047 0, ("vm_fault_prefault: unaligned object offset")); 1048 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1049 VM_OBJECT_RLOCK(backing_object); 1050 VM_OBJECT_RUNLOCK(lobject); 1051 lobject = backing_object; 1052 } 1053 /* 1054 * give-up when a page is not in memory 1055 */ 1056 if (m == NULL) { 1057 VM_OBJECT_RUNLOCK(lobject); 1058 break; 1059 } 1060 if (m->valid == VM_PAGE_BITS_ALL && 1061 (m->flags & PG_FICTITIOUS) == 0) 1062 pmap_enter_quick(pmap, addr, m, entry->protection); 1063 VM_OBJECT_RUNLOCK(lobject); 1064 } 1065} 1066 1067/* 1068 * Hold each of the physical pages that are mapped by the specified range of 1069 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid 1070 * and allow the specified types of access, "prot". If all of the implied 1071 * pages are successfully held, then the number of held pages is returned 1072 * together with pointers to those pages in the array "ma". However, if any 1073 * of the pages cannot be held, -1 is returned. 1074 */ 1075int 1076vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len, 1077 vm_prot_t prot, vm_page_t *ma, int max_count) 1078{ 1079 vm_offset_t end, va; 1080 vm_page_t *mp; 1081 int count; 1082 boolean_t pmap_failed; 1083 1084 if (len == 0) 1085 return (0); 1086 end = round_page(addr + len); 1087 addr = trunc_page(addr); 1088 1089 /* 1090 * Check for illegal addresses. 1091 */ 1092 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map)) 1093 return (-1); 1094 1095 if (atop(end - addr) > max_count) 1096 panic("vm_fault_quick_hold_pages: count > max_count"); 1097 count = atop(end - addr); 1098 1099 /* 1100 * Most likely, the physical pages are resident in the pmap, so it is 1101 * faster to try pmap_extract_and_hold() first. 1102 */ 1103 pmap_failed = FALSE; 1104 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) { 1105 *mp = pmap_extract_and_hold(map->pmap, va, prot); 1106 if (*mp == NULL) 1107 pmap_failed = TRUE; 1108 else if ((prot & VM_PROT_WRITE) != 0 && 1109 (*mp)->dirty != VM_PAGE_BITS_ALL) { 1110 /* 1111 * Explicitly dirty the physical page. Otherwise, the 1112 * caller's changes may go unnoticed because they are 1113 * performed through an unmanaged mapping or by a DMA 1114 * operation. 1115 * 1116 * The object lock is not held here. 1117 * See vm_page_clear_dirty_mask(). 1118 */ 1119 vm_page_dirty(*mp); 1120 } 1121 } 1122 if (pmap_failed) { 1123 /* 1124 * One or more pages could not be held by the pmap. Either no 1125 * page was mapped at the specified virtual address or that 1126 * mapping had insufficient permissions. Attempt to fault in 1127 * and hold these pages. 1128 */ 1129 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) 1130 if (*mp == NULL && vm_fault_hold(map, va, prot, 1131 VM_FAULT_NORMAL, mp) != KERN_SUCCESS) 1132 goto error; 1133 } 1134 return (count); 1135error: 1136 for (mp = ma; mp < ma + count; mp++) 1137 if (*mp != NULL) { 1138 vm_page_lock(*mp); 1139 vm_page_unhold(*mp); 1140 vm_page_unlock(*mp); 1141 } 1142 return (-1); 1143} 1144 1145/* 1146 * vm_fault_wire: 1147 * 1148 * Wire down a range of virtual addresses in a map. 1149 */ 1150int 1151vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1152 boolean_t fictitious) 1153{ 1154 vm_offset_t va; 1155 int rv; 1156 1157 /* 1158 * We simulate a fault to get the page and enter it in the physical 1159 * map. For user wiring, we only ask for read access on currently 1160 * read-only sections. 1161 */ 1162 for (va = start; va < end; va += PAGE_SIZE) { 1163 rv = vm_fault(map, va, VM_PROT_NONE, VM_FAULT_CHANGE_WIRING); 1164 if (rv) { 1165 if (va != start) 1166 vm_fault_unwire(map, start, va, fictitious); 1167 return (rv); 1168 } 1169 } 1170 return (KERN_SUCCESS); 1171} 1172 1173/* 1174 * vm_fault_unwire: 1175 * 1176 * Unwire a range of virtual addresses in a map. 1177 */ 1178void 1179vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1180 boolean_t fictitious) 1181{ 1182 vm_paddr_t pa; 1183 vm_offset_t va; 1184 vm_page_t m; 1185 pmap_t pmap; 1186 1187 pmap = vm_map_pmap(map); 1188 1189 /* 1190 * Since the pages are wired down, we must be able to get their 1191 * mappings from the physical map system. 1192 */ 1193 for (va = start; va < end; va += PAGE_SIZE) { 1194 pa = pmap_extract(pmap, va); 1195 if (pa != 0) { 1196 pmap_change_wiring(pmap, va, FALSE); 1197 if (!fictitious) { 1198 m = PHYS_TO_VM_PAGE(pa); 1199 vm_page_lock(m); 1200 vm_page_unwire(m, TRUE); 1201 vm_page_unlock(m); 1202 } 1203 } 1204 } 1205} 1206 1207/* 1208 * Routine: 1209 * vm_fault_copy_entry 1210 * Function: 1211 * Create new shadow object backing dst_entry with private copy of 1212 * all underlying pages. When src_entry is equal to dst_entry, 1213 * function implements COW for wired-down map entry. Otherwise, 1214 * it forks wired entry into dst_map. 1215 * 1216 * In/out conditions: 1217 * The source and destination maps must be locked for write. 1218 * The source map entry must be wired down (or be a sharing map 1219 * entry corresponding to a main map entry that is wired down). 1220 */ 1221void 1222vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1223 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1224 vm_ooffset_t *fork_charge) 1225{ 1226 vm_object_t backing_object, dst_object, object, src_object; 1227 vm_pindex_t dst_pindex, pindex, src_pindex; 1228 vm_prot_t access, prot; 1229 vm_offset_t vaddr; 1230 vm_page_t dst_m; 1231 vm_page_t src_m; 1232 boolean_t upgrade; 1233 1234#ifdef lint 1235 src_map++; 1236#endif /* lint */ 1237 1238 upgrade = src_entry == dst_entry; 1239 access = prot = dst_entry->protection; 1240 1241 src_object = src_entry->object.vm_object; 1242 src_pindex = OFF_TO_IDX(src_entry->offset); 1243 1244 if (upgrade && (dst_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) { 1245 dst_object = src_object; 1246 vm_object_reference(dst_object); 1247 } else { 1248 /* 1249 * Create the top-level object for the destination entry. (Doesn't 1250 * actually shadow anything - we copy the pages directly.) 1251 */ 1252 dst_object = vm_object_allocate(OBJT_DEFAULT, 1253 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1254#if VM_NRESERVLEVEL > 0 1255 dst_object->flags |= OBJ_COLORED; 1256 dst_object->pg_color = atop(dst_entry->start); 1257#endif 1258 } 1259 1260 VM_OBJECT_WLOCK(dst_object); 1261 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1262 ("vm_fault_copy_entry: vm_object not NULL")); 1263 if (src_object != dst_object) { 1264 dst_entry->object.vm_object = dst_object; 1265 dst_entry->offset = 0; 1266 dst_object->charge = dst_entry->end - dst_entry->start; 1267 } 1268 if (fork_charge != NULL) { 1269 KASSERT(dst_entry->cred == NULL, 1270 ("vm_fault_copy_entry: leaked swp charge")); 1271 dst_object->cred = curthread->td_ucred; 1272 crhold(dst_object->cred); 1273 *fork_charge += dst_object->charge; 1274 } else if (dst_object->cred == NULL) { 1275 KASSERT(dst_entry->cred != NULL, ("no cred for entry %p", 1276 dst_entry)); 1277 dst_object->cred = dst_entry->cred; 1278 dst_entry->cred = NULL; 1279 } 1280 1281 /* 1282 * If not an upgrade, then enter the mappings in the pmap as 1283 * read and/or execute accesses. Otherwise, enter them as 1284 * write accesses. 1285 * 1286 * A writeable large page mapping is only created if all of 1287 * the constituent small page mappings are modified. Marking 1288 * PTEs as modified on inception allows promotion to happen 1289 * without taking potentially large number of soft faults. 1290 */ 1291 if (!upgrade) 1292 access &= ~VM_PROT_WRITE; 1293 1294 /* 1295 * Loop through all of the virtual pages within the entry's 1296 * range, copying each page from the source object to the 1297 * destination object. Since the source is wired, those pages 1298 * must exist. In contrast, the destination is pageable. 1299 * Since the destination object does share any backing storage 1300 * with the source object, all of its pages must be dirtied, 1301 * regardless of whether they can be written. 1302 */ 1303 for (vaddr = dst_entry->start, dst_pindex = 0; 1304 vaddr < dst_entry->end; 1305 vaddr += PAGE_SIZE, dst_pindex++) { 1306again: 1307 /* 1308 * Find the page in the source object, and copy it in. 1309 * Because the source is wired down, the page will be 1310 * in memory. 1311 */ 1312 if (src_object != dst_object) 1313 VM_OBJECT_RLOCK(src_object); 1314 object = src_object; 1315 pindex = src_pindex + dst_pindex; 1316 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1317 (backing_object = object->backing_object) != NULL) { 1318 /* 1319 * Unless the source mapping is read-only or 1320 * it is presently being upgraded from 1321 * read-only, the first object in the shadow 1322 * chain should provide all of the pages. In 1323 * other words, this loop body should never be 1324 * executed when the source mapping is already 1325 * read/write. 1326 */ 1327 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 || 1328 upgrade, 1329 ("vm_fault_copy_entry: main object missing page")); 1330 1331 VM_OBJECT_RLOCK(backing_object); 1332 pindex += OFF_TO_IDX(object->backing_object_offset); 1333 if (object != dst_object) 1334 VM_OBJECT_RUNLOCK(object); 1335 object = backing_object; 1336 } 1337 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing")); 1338 1339 if (object != dst_object) { 1340 /* 1341 * Allocate a page in the destination object. 1342 */ 1343 dst_m = vm_page_alloc(dst_object, (src_object == 1344 dst_object ? src_pindex : 0) + dst_pindex, 1345 VM_ALLOC_NORMAL); 1346 if (dst_m == NULL) { 1347 VM_OBJECT_WUNLOCK(dst_object); 1348 VM_OBJECT_RUNLOCK(object); 1349 VM_WAIT; 1350 VM_OBJECT_WLOCK(dst_object); 1351 goto again; 1352 } 1353 pmap_copy_page(src_m, dst_m); 1354 VM_OBJECT_RUNLOCK(object); 1355 dst_m->valid = VM_PAGE_BITS_ALL; 1356 dst_m->dirty = VM_PAGE_BITS_ALL; 1357 } else { 1358 dst_m = src_m; 1359 if (vm_page_sleep_if_busy(dst_m, "fltupg")) 1360 goto again; 1361 vm_page_xbusy(dst_m); 1362 KASSERT(dst_m->valid == VM_PAGE_BITS_ALL, 1363 ("invalid dst page %p", dst_m)); 1364 } 1365 VM_OBJECT_WUNLOCK(dst_object); 1366 1367 /* 1368 * Enter it in the pmap. If a wired, copy-on-write 1369 * mapping is being replaced by a write-enabled 1370 * mapping, then wire that new mapping. 1371 */ 1372 pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade); 1373 1374 /* 1375 * Mark it no longer busy, and put it on the active list. 1376 */ 1377 VM_OBJECT_WLOCK(dst_object); 1378 1379 if (upgrade) { 1380 if (src_m != dst_m) { 1381 vm_page_lock(src_m); 1382 vm_page_unwire(src_m, 0); 1383 vm_page_unlock(src_m); 1384 vm_page_lock(dst_m); 1385 vm_page_wire(dst_m); 1386 vm_page_unlock(dst_m); 1387 } else { 1388 KASSERT(dst_m->wire_count > 0, 1389 ("dst_m %p is not wired", dst_m)); 1390 } 1391 } else { 1392 vm_page_lock(dst_m); 1393 vm_page_activate(dst_m); 1394 vm_page_unlock(dst_m); 1395 } 1396 vm_page_xunbusy(dst_m); 1397 } 1398 VM_OBJECT_WUNLOCK(dst_object); 1399 if (upgrade) { 1400 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1401 vm_object_deallocate(src_object); 1402 } 1403} 1404 1405 1406/* 1407 * This routine checks around the requested page for other pages that 1408 * might be able to be faulted in. This routine brackets the viable 1409 * pages for the pages to be paged in. 1410 * 1411 * Inputs: 1412 * m, rbehind, rahead 1413 * 1414 * Outputs: 1415 * marray (array of vm_page_t), reqpage (index of requested page) 1416 * 1417 * Return value: 1418 * number of pages in marray 1419 */ 1420static int 1421vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1422 vm_page_t m; 1423 int rbehind; 1424 int rahead; 1425 vm_page_t *marray; 1426 int *reqpage; 1427{ 1428 int i,j; 1429 vm_object_t object; 1430 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1431 vm_page_t rtm; 1432 int cbehind, cahead; 1433 1434 VM_OBJECT_ASSERT_WLOCKED(m->object); 1435 1436 object = m->object; 1437 pindex = m->pindex; 1438 cbehind = cahead = 0; 1439 1440 /* 1441 * if the requested page is not available, then give up now 1442 */ 1443 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1444 return 0; 1445 } 1446 1447 if ((cbehind == 0) && (cahead == 0)) { 1448 *reqpage = 0; 1449 marray[0] = m; 1450 return 1; 1451 } 1452 1453 if (rahead > cahead) { 1454 rahead = cahead; 1455 } 1456 1457 if (rbehind > cbehind) { 1458 rbehind = cbehind; 1459 } 1460 1461 /* 1462 * scan backward for the read behind pages -- in memory 1463 */ 1464 if (pindex > 0) { 1465 if (rbehind > pindex) { 1466 rbehind = pindex; 1467 startpindex = 0; 1468 } else { 1469 startpindex = pindex - rbehind; 1470 } 1471 1472 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1473 rtm->pindex >= startpindex) 1474 startpindex = rtm->pindex + 1; 1475 1476 /* tpindex is unsigned; beware of numeric underflow. */ 1477 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1478 tpindex < pindex; i++, tpindex--) { 1479 1480 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1481 VM_ALLOC_IFNOTCACHED); 1482 if (rtm == NULL) { 1483 /* 1484 * Shift the allocated pages to the 1485 * beginning of the array. 1486 */ 1487 for (j = 0; j < i; j++) { 1488 marray[j] = marray[j + tpindex + 1 - 1489 startpindex]; 1490 } 1491 break; 1492 } 1493 1494 marray[tpindex - startpindex] = rtm; 1495 } 1496 } else { 1497 startpindex = 0; 1498 i = 0; 1499 } 1500 1501 marray[i] = m; 1502 /* page offset of the required page */ 1503 *reqpage = i; 1504 1505 tpindex = pindex + 1; 1506 i++; 1507 1508 /* 1509 * scan forward for the read ahead pages 1510 */ 1511 endpindex = tpindex + rahead; 1512 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1513 endpindex = rtm->pindex; 1514 if (endpindex > object->size) 1515 endpindex = object->size; 1516 1517 for (; tpindex < endpindex; i++, tpindex++) { 1518 1519 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1520 VM_ALLOC_IFNOTCACHED); 1521 if (rtm == NULL) { 1522 break; 1523 } 1524 1525 marray[i] = rtm; 1526 } 1527 1528 /* return number of pages */ 1529 return i; 1530} 1531 1532/* 1533 * Block entry into the machine-independent layer's page fault handler by 1534 * the calling thread. Subsequent calls to vm_fault() by that thread will 1535 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of 1536 * spurious page faults. 1537 */ 1538int 1539vm_fault_disable_pagefaults(void) 1540{ 1541 1542 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR)); 1543} 1544 1545void 1546vm_fault_enable_pagefaults(int save) 1547{ 1548 1549 curthread_pflags_restore(save); 1550} 1551