vm_fault.c revision 270627
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 270627 2014-08-25 20:49:25Z 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 (fs.m->oflags & VPO_UNMANAGED) == 0) { 862 vm_object_set_writeable_dirty(fs.object); 863 864 /* 865 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 866 * if the page is already dirty to prevent data written with 867 * the expectation of being synced from not being synced. 868 * Likewise if this entry does not request NOSYNC then make 869 * sure the page isn't marked NOSYNC. Applications sharing 870 * data should use the same flags to avoid ping ponging. 871 */ 872 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 873 if (fs.m->dirty == 0) 874 fs.m->oflags |= VPO_NOSYNC; 875 } else { 876 fs.m->oflags &= ~VPO_NOSYNC; 877 } 878 879 /* 880 * If the fault is a write, we know that this page is being 881 * written NOW so dirty it explicitly to save on 882 * pmap_is_modified() calls later. 883 * 884 * Also tell the backing pager, if any, that it should remove 885 * any swap backing since the page is now dirty. 886 */ 887 if (((fault_type & VM_PROT_WRITE) != 0 && 888 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) || 889 (fault_flags & VM_FAULT_DIRTY) != 0) { 890 vm_page_dirty(fs.m); 891 vm_pager_page_unswapped(fs.m); 892 } 893 } 894 895 vm_page_assert_xbusied(fs.m); 896 897 /* 898 * Page must be completely valid or it is not fit to 899 * map into user space. vm_pager_get_pages() ensures this. 900 */ 901 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 902 ("vm_fault: page %p partially invalid", fs.m)); 903 VM_OBJECT_WUNLOCK(fs.object); 904 905 /* 906 * Put this page into the physical map. We had to do the unlock above 907 * because pmap_enter() may sleep. We don't put the page 908 * back on the active queue until later so that the pageout daemon 909 * won't find it (yet). 910 */ 911 pmap_enter(fs.map->pmap, vaddr, fs.m, prot, 912 fault_type | (wired ? PMAP_ENTER_WIRED : 0), 0); 913 if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0) 914 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); 915 VM_OBJECT_WLOCK(fs.object); 916 vm_page_lock(fs.m); 917 918 /* 919 * If the page is not wired down, then put it where the pageout daemon 920 * can find it. 921 */ 922 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 923 if (wired) 924 vm_page_wire(fs.m); 925 else 926 vm_page_unwire(fs.m, 1); 927 } else 928 vm_page_activate(fs.m); 929 if (m_hold != NULL) { 930 *m_hold = fs.m; 931 vm_page_hold(fs.m); 932 } 933 vm_page_unlock(fs.m); 934 vm_page_xunbusy(fs.m); 935 936 /* 937 * Unlock everything, and return 938 */ 939 unlock_and_deallocate(&fs); 940 if (hardfault) { 941 PCPU_INC(cnt.v_io_faults); 942 curthread->td_ru.ru_majflt++; 943 } else 944 curthread->td_ru.ru_minflt++; 945 946 return (KERN_SUCCESS); 947} 948 949/* 950 * Speed up the reclamation of up to "distance" pages that precede the 951 * faulting pindex within the first object of the shadow chain. 952 */ 953static void 954vm_fault_cache_behind(const struct faultstate *fs, int distance) 955{ 956 vm_object_t first_object, object; 957 vm_page_t m, m_prev; 958 vm_pindex_t pindex; 959 960 object = fs->object; 961 VM_OBJECT_ASSERT_WLOCKED(object); 962 first_object = fs->first_object; 963 if (first_object != object) { 964 if (!VM_OBJECT_TRYWLOCK(first_object)) { 965 VM_OBJECT_WUNLOCK(object); 966 VM_OBJECT_WLOCK(first_object); 967 VM_OBJECT_WLOCK(object); 968 } 969 } 970 /* Neither fictitious nor unmanaged pages can be cached. */ 971 if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) { 972 if (fs->first_pindex < distance) 973 pindex = 0; 974 else 975 pindex = fs->first_pindex - distance; 976 if (pindex < OFF_TO_IDX(fs->entry->offset)) 977 pindex = OFF_TO_IDX(fs->entry->offset); 978 m = first_object != object ? fs->first_m : fs->m; 979 vm_page_assert_xbusied(m); 980 m_prev = vm_page_prev(m); 981 while ((m = m_prev) != NULL && m->pindex >= pindex && 982 m->valid == VM_PAGE_BITS_ALL) { 983 m_prev = vm_page_prev(m); 984 if (vm_page_busied(m)) 985 continue; 986 vm_page_lock(m); 987 if (m->hold_count == 0 && m->wire_count == 0) { 988 pmap_remove_all(m); 989 vm_page_aflag_clear(m, PGA_REFERENCED); 990 if (m->dirty != 0) 991 vm_page_deactivate(m); 992 else 993 vm_page_cache(m); 994 } 995 vm_page_unlock(m); 996 } 997 } 998 if (first_object != object) 999 VM_OBJECT_WUNLOCK(first_object); 1000} 1001 1002/* 1003 * vm_fault_prefault provides a quick way of clustering 1004 * pagefaults into a processes address space. It is a "cousin" 1005 * of vm_map_pmap_enter, except it runs at page fault time instead 1006 * of mmap time. 1007 */ 1008static void 1009vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) 1010{ 1011 int i; 1012 vm_offset_t addr, starta; 1013 vm_pindex_t pindex; 1014 vm_page_t m; 1015 vm_object_t object; 1016 1017 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 1018 return; 1019 1020 object = entry->object.vm_object; 1021 1022 starta = addra - PFBAK * PAGE_SIZE; 1023 if (starta < entry->start) { 1024 starta = entry->start; 1025 } else if (starta > addra) { 1026 starta = 0; 1027 } 1028 1029 for (i = 0; i < PAGEORDER_SIZE; i++) { 1030 vm_object_t backing_object, lobject; 1031 1032 addr = addra + prefault_pageorder[i]; 1033 if (addr > addra + (PFFOR * PAGE_SIZE)) 1034 addr = 0; 1035 1036 if (addr < starta || addr >= entry->end) 1037 continue; 1038 1039 if (!pmap_is_prefaultable(pmap, addr)) 1040 continue; 1041 1042 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1043 lobject = object; 1044 VM_OBJECT_RLOCK(lobject); 1045 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1046 lobject->type == OBJT_DEFAULT && 1047 (backing_object = lobject->backing_object) != NULL) { 1048 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1049 0, ("vm_fault_prefault: unaligned object offset")); 1050 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1051 VM_OBJECT_RLOCK(backing_object); 1052 VM_OBJECT_RUNLOCK(lobject); 1053 lobject = backing_object; 1054 } 1055 /* 1056 * give-up when a page is not in memory 1057 */ 1058 if (m == NULL) { 1059 VM_OBJECT_RUNLOCK(lobject); 1060 break; 1061 } 1062 if (m->valid == VM_PAGE_BITS_ALL && 1063 (m->flags & PG_FICTITIOUS) == 0) 1064 pmap_enter_quick(pmap, addr, m, entry->protection); 1065 VM_OBJECT_RUNLOCK(lobject); 1066 } 1067} 1068 1069/* 1070 * Hold each of the physical pages that are mapped by the specified range of 1071 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid 1072 * and allow the specified types of access, "prot". If all of the implied 1073 * pages are successfully held, then the number of held pages is returned 1074 * together with pointers to those pages in the array "ma". However, if any 1075 * of the pages cannot be held, -1 is returned. 1076 */ 1077int 1078vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len, 1079 vm_prot_t prot, vm_page_t *ma, int max_count) 1080{ 1081 vm_offset_t end, va; 1082 vm_page_t *mp; 1083 int count; 1084 boolean_t pmap_failed; 1085 1086 if (len == 0) 1087 return (0); 1088 end = round_page(addr + len); 1089 addr = trunc_page(addr); 1090 1091 /* 1092 * Check for illegal addresses. 1093 */ 1094 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map)) 1095 return (-1); 1096 1097 if (atop(end - addr) > max_count) 1098 panic("vm_fault_quick_hold_pages: count > max_count"); 1099 count = atop(end - addr); 1100 1101 /* 1102 * Most likely, the physical pages are resident in the pmap, so it is 1103 * faster to try pmap_extract_and_hold() first. 1104 */ 1105 pmap_failed = FALSE; 1106 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) { 1107 *mp = pmap_extract_and_hold(map->pmap, va, prot); 1108 if (*mp == NULL) 1109 pmap_failed = TRUE; 1110 else if ((prot & VM_PROT_WRITE) != 0 && 1111 (*mp)->dirty != VM_PAGE_BITS_ALL) { 1112 /* 1113 * Explicitly dirty the physical page. Otherwise, the 1114 * caller's changes may go unnoticed because they are 1115 * performed through an unmanaged mapping or by a DMA 1116 * operation. 1117 * 1118 * The object lock is not held here. 1119 * See vm_page_clear_dirty_mask(). 1120 */ 1121 vm_page_dirty(*mp); 1122 } 1123 } 1124 if (pmap_failed) { 1125 /* 1126 * One or more pages could not be held by the pmap. Either no 1127 * page was mapped at the specified virtual address or that 1128 * mapping had insufficient permissions. Attempt to fault in 1129 * and hold these pages. 1130 */ 1131 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) 1132 if (*mp == NULL && vm_fault_hold(map, va, prot, 1133 VM_FAULT_NORMAL, mp) != KERN_SUCCESS) 1134 goto error; 1135 } 1136 return (count); 1137error: 1138 for (mp = ma; mp < ma + count; mp++) 1139 if (*mp != NULL) { 1140 vm_page_lock(*mp); 1141 vm_page_unhold(*mp); 1142 vm_page_unlock(*mp); 1143 } 1144 return (-1); 1145} 1146 1147/* 1148 * vm_fault_wire: 1149 * 1150 * Wire down a range of virtual addresses in a map. 1151 */ 1152int 1153vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1154 boolean_t fictitious) 1155{ 1156 vm_offset_t va; 1157 int rv; 1158 1159 /* 1160 * We simulate a fault to get the page and enter it in the physical 1161 * map. For user wiring, we only ask for read access on currently 1162 * read-only sections. 1163 */ 1164 for (va = start; va < end; va += PAGE_SIZE) { 1165 rv = vm_fault(map, va, VM_PROT_NONE, VM_FAULT_CHANGE_WIRING); 1166 if (rv) { 1167 if (va != start) 1168 vm_fault_unwire(map, start, va, fictitious); 1169 return (rv); 1170 } 1171 } 1172 return (KERN_SUCCESS); 1173} 1174 1175/* 1176 * vm_fault_unwire: 1177 * 1178 * Unwire a range of virtual addresses in a map. 1179 */ 1180void 1181vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1182 boolean_t fictitious) 1183{ 1184 vm_paddr_t pa; 1185 vm_offset_t va; 1186 vm_page_t m; 1187 pmap_t pmap; 1188 1189 pmap = vm_map_pmap(map); 1190 1191 /* 1192 * Since the pages are wired down, we must be able to get their 1193 * mappings from the physical map system. 1194 */ 1195 for (va = start; va < end; va += PAGE_SIZE) { 1196 pa = pmap_extract(pmap, va); 1197 if (pa != 0) { 1198 pmap_change_wiring(pmap, va, FALSE); 1199 if (!fictitious) { 1200 m = PHYS_TO_VM_PAGE(pa); 1201 vm_page_lock(m); 1202 vm_page_unwire(m, TRUE); 1203 vm_page_unlock(m); 1204 } 1205 } 1206 } 1207} 1208 1209/* 1210 * Routine: 1211 * vm_fault_copy_entry 1212 * Function: 1213 * Create new shadow object backing dst_entry with private copy of 1214 * all underlying pages. When src_entry is equal to dst_entry, 1215 * function implements COW for wired-down map entry. Otherwise, 1216 * it forks wired entry into dst_map. 1217 * 1218 * In/out conditions: 1219 * The source and destination maps must be locked for write. 1220 * The source map entry must be wired down (or be a sharing map 1221 * entry corresponding to a main map entry that is wired down). 1222 */ 1223void 1224vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1225 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1226 vm_ooffset_t *fork_charge) 1227{ 1228 vm_object_t backing_object, dst_object, object, src_object; 1229 vm_pindex_t dst_pindex, pindex, src_pindex; 1230 vm_prot_t access, prot; 1231 vm_offset_t vaddr; 1232 vm_page_t dst_m; 1233 vm_page_t src_m; 1234 boolean_t upgrade; 1235 1236#ifdef lint 1237 src_map++; 1238#endif /* lint */ 1239 1240 upgrade = src_entry == dst_entry; 1241 access = prot = dst_entry->protection; 1242 1243 src_object = src_entry->object.vm_object; 1244 src_pindex = OFF_TO_IDX(src_entry->offset); 1245 1246 if (upgrade && (dst_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) { 1247 dst_object = src_object; 1248 vm_object_reference(dst_object); 1249 } else { 1250 /* 1251 * Create the top-level object for the destination entry. (Doesn't 1252 * actually shadow anything - we copy the pages directly.) 1253 */ 1254 dst_object = vm_object_allocate(OBJT_DEFAULT, 1255 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1256#if VM_NRESERVLEVEL > 0 1257 dst_object->flags |= OBJ_COLORED; 1258 dst_object->pg_color = atop(dst_entry->start); 1259#endif 1260 } 1261 1262 VM_OBJECT_WLOCK(dst_object); 1263 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1264 ("vm_fault_copy_entry: vm_object not NULL")); 1265 if (src_object != dst_object) { 1266 dst_entry->object.vm_object = dst_object; 1267 dst_entry->offset = 0; 1268 dst_object->charge = dst_entry->end - dst_entry->start; 1269 } 1270 if (fork_charge != NULL) { 1271 KASSERT(dst_entry->cred == NULL, 1272 ("vm_fault_copy_entry: leaked swp charge")); 1273 dst_object->cred = curthread->td_ucred; 1274 crhold(dst_object->cred); 1275 *fork_charge += dst_object->charge; 1276 } else if (dst_object->cred == NULL) { 1277 KASSERT(dst_entry->cred != NULL, ("no cred for entry %p", 1278 dst_entry)); 1279 dst_object->cred = dst_entry->cred; 1280 dst_entry->cred = NULL; 1281 } 1282 1283 /* 1284 * If not an upgrade, then enter the mappings in the pmap as 1285 * read and/or execute accesses. Otherwise, enter them as 1286 * write accesses. 1287 * 1288 * A writeable large page mapping is only created if all of 1289 * the constituent small page mappings are modified. Marking 1290 * PTEs as modified on inception allows promotion to happen 1291 * without taking potentially large number of soft faults. 1292 */ 1293 if (!upgrade) 1294 access &= ~VM_PROT_WRITE; 1295 1296 /* 1297 * Loop through all of the virtual pages within the entry's 1298 * range, copying each page from the source object to the 1299 * destination object. Since the source is wired, those pages 1300 * must exist. In contrast, the destination is pageable. 1301 * Since the destination object does share any backing storage 1302 * with the source object, all of its pages must be dirtied, 1303 * regardless of whether they can be written. 1304 */ 1305 for (vaddr = dst_entry->start, dst_pindex = 0; 1306 vaddr < dst_entry->end; 1307 vaddr += PAGE_SIZE, dst_pindex++) { 1308again: 1309 /* 1310 * Find the page in the source object, and copy it in. 1311 * Because the source is wired down, the page will be 1312 * in memory. 1313 */ 1314 if (src_object != dst_object) 1315 VM_OBJECT_RLOCK(src_object); 1316 object = src_object; 1317 pindex = src_pindex + dst_pindex; 1318 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1319 (backing_object = object->backing_object) != NULL) { 1320 /* 1321 * Unless the source mapping is read-only or 1322 * it is presently being upgraded from 1323 * read-only, the first object in the shadow 1324 * chain should provide all of the pages. In 1325 * other words, this loop body should never be 1326 * executed when the source mapping is already 1327 * read/write. 1328 */ 1329 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 || 1330 upgrade, 1331 ("vm_fault_copy_entry: main object missing page")); 1332 1333 VM_OBJECT_RLOCK(backing_object); 1334 pindex += OFF_TO_IDX(object->backing_object_offset); 1335 if (object != dst_object) 1336 VM_OBJECT_RUNLOCK(object); 1337 object = backing_object; 1338 } 1339 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing")); 1340 1341 if (object != dst_object) { 1342 /* 1343 * Allocate a page in the destination object. 1344 */ 1345 dst_m = vm_page_alloc(dst_object, (src_object == 1346 dst_object ? src_pindex : 0) + dst_pindex, 1347 VM_ALLOC_NORMAL); 1348 if (dst_m == NULL) { 1349 VM_OBJECT_WUNLOCK(dst_object); 1350 VM_OBJECT_RUNLOCK(object); 1351 VM_WAIT; 1352 VM_OBJECT_WLOCK(dst_object); 1353 goto again; 1354 } 1355 pmap_copy_page(src_m, dst_m); 1356 VM_OBJECT_RUNLOCK(object); 1357 dst_m->valid = VM_PAGE_BITS_ALL; 1358 dst_m->dirty = VM_PAGE_BITS_ALL; 1359 } else { 1360 dst_m = src_m; 1361 if (vm_page_sleep_if_busy(dst_m, "fltupg")) 1362 goto again; 1363 vm_page_xbusy(dst_m); 1364 KASSERT(dst_m->valid == VM_PAGE_BITS_ALL, 1365 ("invalid dst page %p", dst_m)); 1366 } 1367 VM_OBJECT_WUNLOCK(dst_object); 1368 1369 /* 1370 * Enter it in the pmap. If a wired, copy-on-write 1371 * mapping is being replaced by a write-enabled 1372 * mapping, then wire that new mapping. 1373 */ 1374 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, 1375 access | (upgrade ? PMAP_ENTER_WIRED : 0), 0); 1376 1377 /* 1378 * Mark it no longer busy, and put it on the active list. 1379 */ 1380 VM_OBJECT_WLOCK(dst_object); 1381 1382 if (upgrade) { 1383 if (src_m != dst_m) { 1384 vm_page_lock(src_m); 1385 vm_page_unwire(src_m, 0); 1386 vm_page_unlock(src_m); 1387 vm_page_lock(dst_m); 1388 vm_page_wire(dst_m); 1389 vm_page_unlock(dst_m); 1390 } else { 1391 KASSERT(dst_m->wire_count > 0, 1392 ("dst_m %p is not wired", dst_m)); 1393 } 1394 } else { 1395 vm_page_lock(dst_m); 1396 vm_page_activate(dst_m); 1397 vm_page_unlock(dst_m); 1398 } 1399 vm_page_xunbusy(dst_m); 1400 } 1401 VM_OBJECT_WUNLOCK(dst_object); 1402 if (upgrade) { 1403 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1404 vm_object_deallocate(src_object); 1405 } 1406} 1407 1408 1409/* 1410 * This routine checks around the requested page for other pages that 1411 * might be able to be faulted in. This routine brackets the viable 1412 * pages for the pages to be paged in. 1413 * 1414 * Inputs: 1415 * m, rbehind, rahead 1416 * 1417 * Outputs: 1418 * marray (array of vm_page_t), reqpage (index of requested page) 1419 * 1420 * Return value: 1421 * number of pages in marray 1422 */ 1423static int 1424vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1425 vm_page_t m; 1426 int rbehind; 1427 int rahead; 1428 vm_page_t *marray; 1429 int *reqpage; 1430{ 1431 int i,j; 1432 vm_object_t object; 1433 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1434 vm_page_t rtm; 1435 int cbehind, cahead; 1436 1437 VM_OBJECT_ASSERT_WLOCKED(m->object); 1438 1439 object = m->object; 1440 pindex = m->pindex; 1441 cbehind = cahead = 0; 1442 1443 /* 1444 * if the requested page is not available, then give up now 1445 */ 1446 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1447 return 0; 1448 } 1449 1450 if ((cbehind == 0) && (cahead == 0)) { 1451 *reqpage = 0; 1452 marray[0] = m; 1453 return 1; 1454 } 1455 1456 if (rahead > cahead) { 1457 rahead = cahead; 1458 } 1459 1460 if (rbehind > cbehind) { 1461 rbehind = cbehind; 1462 } 1463 1464 /* 1465 * scan backward for the read behind pages -- in memory 1466 */ 1467 if (pindex > 0) { 1468 if (rbehind > pindex) { 1469 rbehind = pindex; 1470 startpindex = 0; 1471 } else { 1472 startpindex = pindex - rbehind; 1473 } 1474 1475 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1476 rtm->pindex >= startpindex) 1477 startpindex = rtm->pindex + 1; 1478 1479 /* tpindex is unsigned; beware of numeric underflow. */ 1480 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1481 tpindex < pindex; i++, tpindex--) { 1482 1483 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1484 VM_ALLOC_IFNOTCACHED); 1485 if (rtm == NULL) { 1486 /* 1487 * Shift the allocated pages to the 1488 * beginning of the array. 1489 */ 1490 for (j = 0; j < i; j++) { 1491 marray[j] = marray[j + tpindex + 1 - 1492 startpindex]; 1493 } 1494 break; 1495 } 1496 1497 marray[tpindex - startpindex] = rtm; 1498 } 1499 } else { 1500 startpindex = 0; 1501 i = 0; 1502 } 1503 1504 marray[i] = m; 1505 /* page offset of the required page */ 1506 *reqpage = i; 1507 1508 tpindex = pindex + 1; 1509 i++; 1510 1511 /* 1512 * scan forward for the read ahead pages 1513 */ 1514 endpindex = tpindex + rahead; 1515 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1516 endpindex = rtm->pindex; 1517 if (endpindex > object->size) 1518 endpindex = object->size; 1519 1520 for (; tpindex < endpindex; i++, tpindex++) { 1521 1522 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1523 VM_ALLOC_IFNOTCACHED); 1524 if (rtm == NULL) { 1525 break; 1526 } 1527 1528 marray[i] = rtm; 1529 } 1530 1531 /* return number of pages */ 1532 return i; 1533} 1534 1535/* 1536 * Block entry into the machine-independent layer's page fault handler by 1537 * the calling thread. Subsequent calls to vm_fault() by that thread will 1538 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of 1539 * spurious page faults. 1540 */ 1541int 1542vm_fault_disable_pagefaults(void) 1543{ 1544 1545 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR)); 1546} 1547 1548void 1549vm_fault_enable_pagefaults(int save) 1550{ 1551 1552 curthread_pflags_restore(save); 1553} 1554