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("$FreeBSD$"); 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/mutex.h> 85#include <sys/proc.h> 86#include <sys/resourcevar.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#include <sys/mount.h> /* XXX Temporary for VFS_LOCK_GIANT() */ 106 107#define PFBAK 4 108#define PFFOR 4 109#define PAGEORDER_SIZE (PFBAK+PFFOR) 110 111static int prefault_pageorder[] = { 112 -1 * PAGE_SIZE, 1 * PAGE_SIZE, 113 -2 * PAGE_SIZE, 2 * PAGE_SIZE, 114 -3 * PAGE_SIZE, 3 * PAGE_SIZE, 115 -4 * PAGE_SIZE, 4 * PAGE_SIZE 116}; 117 118static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); 119static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t); 120 121#define VM_FAULT_READ_BEHIND 8 122#define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX) 123#define VM_FAULT_NINCR (VM_FAULT_READ_MAX / VM_FAULT_READ_BEHIND) 124#define VM_FAULT_SUM (VM_FAULT_NINCR * (VM_FAULT_NINCR + 1) / 2) 125#define VM_FAULT_CACHE_BEHIND (VM_FAULT_READ_BEHIND * VM_FAULT_SUM) 126 127struct faultstate { 128 vm_page_t m; 129 vm_object_t object; 130 vm_pindex_t pindex; 131 vm_page_t first_m; 132 vm_object_t first_object; 133 vm_pindex_t first_pindex; 134 vm_map_t map; 135 vm_map_entry_t entry; 136 int lookup_still_valid; 137 struct vnode *vp; 138 int vfslocked; 139}; 140 141static void vm_fault_cache_behind(const struct faultstate *fs, int distance); 142 143static inline void 144release_page(struct faultstate *fs) 145{ 146 147 vm_page_wakeup(fs->m); 148 vm_page_lock(fs->m); 149 vm_page_deactivate(fs->m); 150 vm_page_unlock(fs->m); 151 fs->m = NULL; 152} 153 154static inline void 155unlock_map(struct faultstate *fs) 156{ 157 158 if (fs->lookup_still_valid) { 159 vm_map_lookup_done(fs->map, fs->entry); 160 fs->lookup_still_valid = FALSE; 161 } 162} 163 164static void 165unlock_and_deallocate(struct faultstate *fs) 166{ 167 168 vm_object_pip_wakeup(fs->object); 169 VM_OBJECT_UNLOCK(fs->object); 170 if (fs->object != fs->first_object) { 171 VM_OBJECT_LOCK(fs->first_object); 172 vm_page_lock(fs->first_m); 173 vm_page_free(fs->first_m); 174 vm_page_unlock(fs->first_m); 175 vm_object_pip_wakeup(fs->first_object); 176 VM_OBJECT_UNLOCK(fs->first_object); 177 fs->first_m = NULL; 178 } 179 vm_object_deallocate(fs->first_object); 180 unlock_map(fs); 181 if (fs->vp != NULL) { 182 vput(fs->vp); 183 fs->vp = NULL; 184 } 185 VFS_UNLOCK_GIANT(fs->vfslocked); 186 fs->vfslocked = 0; 187} 188 189/* 190 * TRYPAGER - used by vm_fault to calculate whether the pager for the 191 * current object *might* contain the page. 192 * 193 * default objects are zero-fill, there is no real pager. 194 */ 195#define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 196 ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 || wired)) 197 198/* 199 * vm_fault: 200 * 201 * Handle a page fault occurring at the given address, 202 * requiring the given permissions, in the map specified. 203 * If successful, the page is inserted into the 204 * associated physical map. 205 * 206 * NOTE: the given address should be truncated to the 207 * proper page address. 208 * 209 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 210 * a standard error specifying why the fault is fatal is returned. 211 * 212 * The map in question must be referenced, and remains so. 213 * Caller may hold no locks. 214 */ 215int 216vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 217 int fault_flags) 218{ 219 struct thread *td; 220 int result; 221 222 td = curthread; 223 if ((td->td_pflags & TDP_NOFAULTING) != 0) 224 return (KERN_PROTECTION_FAILURE); 225#ifdef KTRACE 226 if (map != kernel_map && KTRPOINT(td, KTR_FAULT)) 227 ktrfault(vaddr, fault_type); 228#endif 229 result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags, 230 NULL); 231#ifdef KTRACE 232 if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND)) 233 ktrfaultend(result); 234#endif 235 return (result); 236} 237 238int 239vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 240 int fault_flags, vm_page_t *m_hold) 241{ 242 vm_prot_t prot; 243 long ahead, behind; 244 int alloc_req, era, faultcount, nera, reqpage, result; 245 boolean_t growstack, is_first_object_locked, wired; 246 int map_generation; 247 vm_object_t next_object; 248 vm_page_t marray[VM_FAULT_READ_MAX]; 249 int hardfault; 250 struct faultstate fs; 251 struct vnode *vp; 252 int locked, error; 253 254 hardfault = 0; 255 growstack = TRUE; 256 PCPU_INC(cnt.v_vm_faults); 257 fs.vp = NULL; 258 fs.vfslocked = 0; 259 faultcount = reqpage = 0; 260 261RetryFault:; 262 263 /* 264 * Find the backing store object and offset into it to begin the 265 * search. 266 */ 267 fs.map = map; 268 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 269 &fs.first_object, &fs.first_pindex, &prot, &wired); 270 if (result != KERN_SUCCESS) { 271 if (growstack && result == KERN_INVALID_ADDRESS && 272 map != kernel_map) { 273 result = vm_map_growstack(curproc, vaddr); 274 if (result != KERN_SUCCESS) 275 return (KERN_FAILURE); 276 growstack = FALSE; 277 goto RetryFault; 278 } 279 return (result); 280 } 281 282 map_generation = fs.map->timestamp; 283 284 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 285 if ((curthread->td_pflags & TDP_DEVMEMIO) != 0) { 286 vm_map_unlock_read(fs.map); 287 return (KERN_FAILURE); 288 } 289 panic("vm_fault: fault on nofault entry, addr: %lx", 290 (u_long)vaddr); 291 } 292 293 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION && 294 fs.entry->wiring_thread != curthread) { 295 vm_map_unlock_read(fs.map); 296 vm_map_lock(fs.map); 297 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) && 298 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) { 299 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP; 300 vm_map_unlock_and_wait(fs.map, 0); 301 } else 302 vm_map_unlock(fs.map); 303 goto RetryFault; 304 } 305 306 /* 307 * Make a reference to this object to prevent its disposal while we 308 * are messing with it. Once we have the reference, the map is free 309 * to be diddled. Since objects reference their shadows (and copies), 310 * they will stay around as well. 311 * 312 * Bump the paging-in-progress count to prevent size changes (e.g. 313 * truncation operations) during I/O. This must be done after 314 * obtaining the vnode lock in order to avoid possible deadlocks. 315 */ 316 VM_OBJECT_LOCK(fs.first_object); 317 vm_object_reference_locked(fs.first_object); 318 vm_object_pip_add(fs.first_object, 1); 319 320 fs.lookup_still_valid = TRUE; 321 322 if (wired) 323 fault_type = prot | (fault_type & VM_PROT_COPY); 324 325 fs.first_m = NULL; 326 327 /* 328 * Search for the page at object/offset. 329 */ 330 fs.object = fs.first_object; 331 fs.pindex = fs.first_pindex; 332 while (TRUE) { 333 /* 334 * If the object is dead, we stop here 335 */ 336 if (fs.object->flags & OBJ_DEAD) { 337 unlock_and_deallocate(&fs); 338 return (KERN_PROTECTION_FAILURE); 339 } 340 341 /* 342 * See if page is resident 343 */ 344 fs.m = vm_page_lookup(fs.object, fs.pindex); 345 if (fs.m != NULL) { 346 /* 347 * check for page-based copy on write. 348 * We check fs.object == fs.first_object so 349 * as to ensure the legacy COW mechanism is 350 * used when the page in question is part of 351 * a shadow object. Otherwise, vm_page_cowfault() 352 * removes the page from the backing object, 353 * which is not what we want. 354 */ 355 vm_page_lock(fs.m); 356 if ((fs.m->cow) && 357 (fault_type & VM_PROT_WRITE) && 358 (fs.object == fs.first_object)) { 359 vm_page_cowfault(fs.m); 360 unlock_and_deallocate(&fs); 361 goto RetryFault; 362 } 363 364 /* 365 * Wait/Retry if the page is busy. We have to do this 366 * if the page is busy via either VPO_BUSY or 367 * vm_page_t->busy because the vm_pager may be using 368 * vm_page_t->busy for pageouts ( and even pageins if 369 * it is the vnode pager ), and we could end up trying 370 * to pagein and pageout the same page simultaneously. 371 * 372 * We can theoretically allow the busy case on a read 373 * fault if the page is marked valid, but since such 374 * pages are typically already pmap'd, putting that 375 * special case in might be more effort then it is 376 * worth. We cannot under any circumstances mess 377 * around with a vm_page_t->busy page except, perhaps, 378 * to pmap it. 379 */ 380 if ((fs.m->oflags & VPO_BUSY) || fs.m->busy) { 381 /* 382 * Reference the page before unlocking and 383 * sleeping so that the page daemon is less 384 * likely to reclaim it. 385 */ 386 vm_page_aflag_set(fs.m, PGA_REFERENCED); 387 vm_page_unlock(fs.m); 388 if (fs.object != fs.first_object) { 389 if (!VM_OBJECT_TRYLOCK( 390 fs.first_object)) { 391 VM_OBJECT_UNLOCK(fs.object); 392 VM_OBJECT_LOCK(fs.first_object); 393 VM_OBJECT_LOCK(fs.object); 394 } 395 vm_page_lock(fs.first_m); 396 vm_page_free(fs.first_m); 397 vm_page_unlock(fs.first_m); 398 vm_object_pip_wakeup(fs.first_object); 399 VM_OBJECT_UNLOCK(fs.first_object); 400 fs.first_m = NULL; 401 } 402 unlock_map(&fs); 403 if (fs.m == vm_page_lookup(fs.object, 404 fs.pindex)) { 405 vm_page_sleep_if_busy(fs.m, TRUE, 406 "vmpfw"); 407 } 408 vm_object_pip_wakeup(fs.object); 409 VM_OBJECT_UNLOCK(fs.object); 410 PCPU_INC(cnt.v_intrans); 411 vm_object_deallocate(fs.first_object); 412 goto RetryFault; 413 } 414 vm_pageq_remove(fs.m); 415 vm_page_unlock(fs.m); 416 417 /* 418 * Mark page busy for other processes, and the 419 * pagedaemon. If it still isn't completely valid 420 * (readable), jump to readrest, else break-out ( we 421 * found the page ). 422 */ 423 vm_page_busy(fs.m); 424 if (fs.m->valid != VM_PAGE_BITS_ALL) 425 goto readrest; 426 break; 427 } 428 429 /* 430 * Page is not resident, If this is the search termination 431 * or the pager might contain the page, allocate a new page. 432 */ 433 if (TRYPAGER || fs.object == fs.first_object) { 434 if (fs.pindex >= fs.object->size) { 435 unlock_and_deallocate(&fs); 436 return (KERN_PROTECTION_FAILURE); 437 } 438 439 /* 440 * Allocate a new page for this object/offset pair. 441 * 442 * Unlocked read of the p_flag is harmless. At 443 * worst, the P_KILLED might be not observed 444 * there, and allocation can fail, causing 445 * restart and new reading of the p_flag. 446 */ 447 fs.m = NULL; 448 if (!vm_page_count_severe() || P_KILLED(curproc)) { 449#if VM_NRESERVLEVEL > 0 450 if ((fs.object->flags & OBJ_COLORED) == 0) { 451 fs.object->flags |= OBJ_COLORED; 452 fs.object->pg_color = atop(vaddr) - 453 fs.pindex; 454 } 455#endif 456 alloc_req = P_KILLED(curproc) ? 457 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 458 if (fs.object->type != OBJT_VNODE && 459 fs.object->backing_object == NULL) 460 alloc_req |= VM_ALLOC_ZERO; 461 fs.m = vm_page_alloc(fs.object, fs.pindex, 462 alloc_req); 463 } 464 if (fs.m == NULL) { 465 unlock_and_deallocate(&fs); 466 VM_WAITPFAULT; 467 goto RetryFault; 468 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 469 break; 470 } 471 472readrest: 473 /* 474 * We have found a valid page or we have allocated a new page. 475 * The page thus may not be valid or may not be entirely 476 * valid. 477 * 478 * Attempt to fault-in the page if there is a chance that the 479 * pager has it, and potentially fault in additional pages 480 * at the same time. 481 */ 482 if (TRYPAGER) { 483 int rv; 484 u_char behavior = vm_map_entry_behavior(fs.entry); 485 486 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 487 P_KILLED(curproc)) { 488 behind = 0; 489 ahead = 0; 490 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) { 491 behind = 0; 492 ahead = atop(fs.entry->end - vaddr) - 1; 493 if (ahead > VM_FAULT_READ_AHEAD_MAX) 494 ahead = VM_FAULT_READ_AHEAD_MAX; 495 if (fs.pindex == fs.entry->next_read) 496 vm_fault_cache_behind(&fs, 497 VM_FAULT_READ_MAX); 498 } else { 499 /* 500 * If this is a sequential page fault, then 501 * arithmetically increase the number of pages 502 * in the read-ahead window. Otherwise, reset 503 * the read-ahead window to its smallest size. 504 */ 505 behind = atop(vaddr - fs.entry->start); 506 if (behind > VM_FAULT_READ_BEHIND) 507 behind = VM_FAULT_READ_BEHIND; 508 ahead = atop(fs.entry->end - vaddr) - 1; 509 era = fs.entry->read_ahead; 510 if (fs.pindex == fs.entry->next_read) { 511 nera = era + behind; 512 if (nera > VM_FAULT_READ_AHEAD_MAX) 513 nera = VM_FAULT_READ_AHEAD_MAX; 514 behind = 0; 515 if (ahead > nera) 516 ahead = nera; 517 if (era == VM_FAULT_READ_AHEAD_MAX) 518 vm_fault_cache_behind(&fs, 519 VM_FAULT_CACHE_BEHIND); 520 } else if (ahead > VM_FAULT_READ_AHEAD_MIN) 521 ahead = VM_FAULT_READ_AHEAD_MIN; 522 if (era != ahead) 523 fs.entry->read_ahead = ahead; 524 } 525 526 /* 527 * Call the pager to retrieve the data, if any, after 528 * releasing the lock on the map. We hold a ref on 529 * fs.object and the pages are VPO_BUSY'd. 530 */ 531 unlock_map(&fs); 532 533vnode_lock: 534 if (fs.object->type == OBJT_VNODE) { 535 vp = fs.object->handle; 536 if (vp == fs.vp) 537 goto vnode_locked; 538 else if (fs.vp != NULL) { 539 vput(fs.vp); 540 fs.vp = NULL; 541 } 542 locked = VOP_ISLOCKED(vp); 543 544 if (VFS_NEEDSGIANT(vp->v_mount) && !fs.vfslocked) { 545 fs.vfslocked = 1; 546 if (!mtx_trylock(&Giant)) { 547 VM_OBJECT_UNLOCK(fs.object); 548 mtx_lock(&Giant); 549 VM_OBJECT_LOCK(fs.object); 550 goto vnode_lock; 551 } 552 } 553 if (locked != LK_EXCLUSIVE) 554 locked = LK_SHARED; 555 /* Do not sleep for vnode lock while fs.m is busy */ 556 error = vget(vp, locked | LK_CANRECURSE | 557 LK_NOWAIT, curthread); 558 if (error != 0) { 559 int vfslocked; 560 561 vfslocked = fs.vfslocked; 562 fs.vfslocked = 0; /* Keep Giant */ 563 vhold(vp); 564 release_page(&fs); 565 unlock_and_deallocate(&fs); 566 error = vget(vp, locked | LK_RETRY | 567 LK_CANRECURSE, curthread); 568 vdrop(vp); 569 fs.vp = vp; 570 fs.vfslocked = vfslocked; 571 KASSERT(error == 0, 572 ("vm_fault: vget failed")); 573 goto RetryFault; 574 } 575 fs.vp = vp; 576 } 577vnode_locked: 578 KASSERT(fs.vp == NULL || !fs.map->system_map, 579 ("vm_fault: vnode-backed object mapped by system map")); 580 581 /* 582 * now we find out if any other pages should be paged 583 * in at this time this routine checks to see if the 584 * pages surrounding this fault reside in the same 585 * object as the page for this fault. If they do, 586 * then they are faulted in also into the object. The 587 * array "marray" returned contains an array of 588 * vm_page_t structs where one of them is the 589 * vm_page_t passed to the routine. The reqpage 590 * return value is the index into the marray for the 591 * vm_page_t passed to the routine. 592 * 593 * fs.m plus the additional pages are VPO_BUSY'd. 594 */ 595 faultcount = vm_fault_additional_pages( 596 fs.m, behind, ahead, marray, &reqpage); 597 598 rv = faultcount ? 599 vm_pager_get_pages(fs.object, marray, faultcount, 600 reqpage) : VM_PAGER_FAIL; 601 602 if (rv == VM_PAGER_OK) { 603 /* 604 * Found the page. Leave it busy while we play 605 * with it. 606 */ 607 608 /* 609 * Relookup in case pager changed page. Pager 610 * is responsible for disposition of old page 611 * if moved. 612 */ 613 fs.m = vm_page_lookup(fs.object, fs.pindex); 614 if (!fs.m) { 615 unlock_and_deallocate(&fs); 616 goto RetryFault; 617 } 618 619 hardfault++; 620 break; /* break to PAGE HAS BEEN FOUND */ 621 } 622 /* 623 * Remove the bogus page (which does not exist at this 624 * object/offset); before doing so, we must get back 625 * our object lock to preserve our invariant. 626 * 627 * Also wake up any other process that may want to bring 628 * in this page. 629 * 630 * If this is the top-level object, we must leave the 631 * busy page to prevent another process from rushing 632 * past us, and inserting the page in that object at 633 * the same time that we are. 634 */ 635 if (rv == VM_PAGER_ERROR) 636 printf("vm_fault: pager read error, pid %d (%s)\n", 637 curproc->p_pid, curproc->p_comm); 638 /* 639 * Data outside the range of the pager or an I/O error 640 */ 641 /* 642 * XXX - the check for kernel_map is a kludge to work 643 * around having the machine panic on a kernel space 644 * fault w/ I/O error. 645 */ 646 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 647 (rv == VM_PAGER_BAD)) { 648 vm_page_lock(fs.m); 649 vm_page_free(fs.m); 650 vm_page_unlock(fs.m); 651 fs.m = NULL; 652 unlock_and_deallocate(&fs); 653 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 654 } 655 if (fs.object != fs.first_object) { 656 vm_page_lock(fs.m); 657 vm_page_free(fs.m); 658 vm_page_unlock(fs.m); 659 fs.m = NULL; 660 /* 661 * XXX - we cannot just fall out at this 662 * point, m has been freed and is invalid! 663 */ 664 } 665 } 666 667 /* 668 * We get here if the object has default pager (or unwiring) 669 * or the pager doesn't have the page. 670 */ 671 if (fs.object == fs.first_object) 672 fs.first_m = fs.m; 673 674 /* 675 * Move on to the next object. Lock the next object before 676 * unlocking the current one. 677 */ 678 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 679 next_object = fs.object->backing_object; 680 if (next_object == NULL) { 681 /* 682 * If there's no object left, fill the page in the top 683 * object with zeros. 684 */ 685 if (fs.object != fs.first_object) { 686 vm_object_pip_wakeup(fs.object); 687 VM_OBJECT_UNLOCK(fs.object); 688 689 fs.object = fs.first_object; 690 fs.pindex = fs.first_pindex; 691 fs.m = fs.first_m; 692 VM_OBJECT_LOCK(fs.object); 693 } 694 fs.first_m = NULL; 695 696 /* 697 * Zero the page if necessary and mark it valid. 698 */ 699 if ((fs.m->flags & PG_ZERO) == 0) { 700 pmap_zero_page(fs.m); 701 } else { 702 PCPU_INC(cnt.v_ozfod); 703 } 704 PCPU_INC(cnt.v_zfod); 705 fs.m->valid = VM_PAGE_BITS_ALL; 706 break; /* break to PAGE HAS BEEN FOUND */ 707 } else { 708 KASSERT(fs.object != next_object, 709 ("object loop %p", next_object)); 710 VM_OBJECT_LOCK(next_object); 711 vm_object_pip_add(next_object, 1); 712 if (fs.object != fs.first_object) 713 vm_object_pip_wakeup(fs.object); 714 VM_OBJECT_UNLOCK(fs.object); 715 fs.object = next_object; 716 } 717 } 718 719 KASSERT((fs.m->oflags & VPO_BUSY) != 0, 720 ("vm_fault: not busy after main loop")); 721 722 /* 723 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 724 * is held.] 725 */ 726 727 /* 728 * If the page is being written, but isn't already owned by the 729 * top-level object, we have to copy it into a new page owned by the 730 * top-level object. 731 */ 732 if (fs.object != fs.first_object) { 733 /* 734 * We only really need to copy if we want to write it. 735 */ 736 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 737 /* 738 * This allows pages to be virtually copied from a 739 * backing_object into the first_object, where the 740 * backing object has no other refs to it, and cannot 741 * gain any more refs. Instead of a bcopy, we just 742 * move the page from the backing object to the 743 * first object. Note that we must mark the page 744 * dirty in the first object so that it will go out 745 * to swap when needed. 746 */ 747 is_first_object_locked = FALSE; 748 if ( 749 /* 750 * Only one shadow object 751 */ 752 (fs.object->shadow_count == 1) && 753 /* 754 * No COW refs, except us 755 */ 756 (fs.object->ref_count == 1) && 757 /* 758 * No one else can look this object up 759 */ 760 (fs.object->handle == NULL) && 761 /* 762 * No other ways to look the object up 763 */ 764 ((fs.object->type == OBJT_DEFAULT) || 765 (fs.object->type == OBJT_SWAP)) && 766 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) && 767 /* 768 * We don't chase down the shadow chain 769 */ 770 fs.object == fs.first_object->backing_object) { 771 /* 772 * get rid of the unnecessary page 773 */ 774 vm_page_lock(fs.first_m); 775 vm_page_free(fs.first_m); 776 vm_page_unlock(fs.first_m); 777 /* 778 * grab the page and put it into the 779 * process'es object. The page is 780 * automatically made dirty. 781 */ 782 vm_page_lock(fs.m); 783 vm_page_rename(fs.m, fs.first_object, fs.first_pindex); 784 vm_page_unlock(fs.m); 785 vm_page_busy(fs.m); 786 fs.first_m = fs.m; 787 fs.m = NULL; 788 PCPU_INC(cnt.v_cow_optim); 789 } else { 790 /* 791 * Oh, well, lets copy it. 792 */ 793 pmap_copy_page(fs.m, fs.first_m); 794 fs.first_m->valid = VM_PAGE_BITS_ALL; 795 if (wired && (fault_flags & 796 VM_FAULT_CHANGE_WIRING) == 0) { 797 vm_page_lock(fs.first_m); 798 vm_page_wire(fs.first_m); 799 vm_page_unlock(fs.first_m); 800 801 vm_page_lock(fs.m); 802 vm_page_unwire(fs.m, FALSE); 803 vm_page_unlock(fs.m); 804 } 805 /* 806 * We no longer need the old page or object. 807 */ 808 release_page(&fs); 809 } 810 /* 811 * fs.object != fs.first_object due to above 812 * conditional 813 */ 814 vm_object_pip_wakeup(fs.object); 815 VM_OBJECT_UNLOCK(fs.object); 816 /* 817 * Only use the new page below... 818 */ 819 fs.object = fs.first_object; 820 fs.pindex = fs.first_pindex; 821 fs.m = fs.first_m; 822 if (!is_first_object_locked) 823 VM_OBJECT_LOCK(fs.object); 824 PCPU_INC(cnt.v_cow_faults); 825 curthread->td_cow++; 826 } else { 827 prot &= ~VM_PROT_WRITE; 828 } 829 } 830 831 /* 832 * We must verify that the maps have not changed since our last 833 * lookup. 834 */ 835 if (!fs.lookup_still_valid) { 836 vm_object_t retry_object; 837 vm_pindex_t retry_pindex; 838 vm_prot_t retry_prot; 839 840 if (!vm_map_trylock_read(fs.map)) { 841 release_page(&fs); 842 unlock_and_deallocate(&fs); 843 goto RetryFault; 844 } 845 fs.lookup_still_valid = TRUE; 846 if (fs.map->timestamp != map_generation) { 847 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 848 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 849 850 /* 851 * If we don't need the page any longer, put it on the inactive 852 * list (the easiest thing to do here). If no one needs it, 853 * pageout will grab it eventually. 854 */ 855 if (result != KERN_SUCCESS) { 856 release_page(&fs); 857 unlock_and_deallocate(&fs); 858 859 /* 860 * If retry of map lookup would have blocked then 861 * retry fault from start. 862 */ 863 if (result == KERN_FAILURE) 864 goto RetryFault; 865 return (result); 866 } 867 if ((retry_object != fs.first_object) || 868 (retry_pindex != fs.first_pindex)) { 869 release_page(&fs); 870 unlock_and_deallocate(&fs); 871 goto RetryFault; 872 } 873 874 /* 875 * Check whether the protection has changed or the object has 876 * been copied while we left the map unlocked. Changing from 877 * read to write permission is OK - we leave the page 878 * write-protected, and catch the write fault. Changing from 879 * write to read permission means that we can't mark the page 880 * write-enabled after all. 881 */ 882 prot &= retry_prot; 883 } 884 } 885 /* 886 * If the page was filled by a pager, update the map entry's 887 * last read offset. Since the pager does not return the 888 * actual set of pages that it read, this update is based on 889 * the requested set. Typically, the requested and actual 890 * sets are the same. 891 * 892 * XXX The following assignment modifies the map 893 * without holding a write lock on it. 894 */ 895 if (hardfault) 896 fs.entry->next_read = fs.pindex + faultcount - reqpage; 897 898 if ((prot & VM_PROT_WRITE) != 0 || 899 (fault_flags & VM_FAULT_DIRTY) != 0) { 900 vm_object_set_writeable_dirty(fs.object); 901 902 /* 903 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 904 * if the page is already dirty to prevent data written with 905 * the expectation of being synced from not being synced. 906 * Likewise if this entry does not request NOSYNC then make 907 * sure the page isn't marked NOSYNC. Applications sharing 908 * data should use the same flags to avoid ping ponging. 909 */ 910 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 911 if (fs.m->dirty == 0) 912 fs.m->oflags |= VPO_NOSYNC; 913 } else { 914 fs.m->oflags &= ~VPO_NOSYNC; 915 } 916 917 /* 918 * If the fault is a write, we know that this page is being 919 * written NOW so dirty it explicitly to save on 920 * pmap_is_modified() calls later. 921 * 922 * Also tell the backing pager, if any, that it should remove 923 * any swap backing since the page is now dirty. 924 */ 925 if (((fault_type & VM_PROT_WRITE) != 0 && 926 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) || 927 (fault_flags & VM_FAULT_DIRTY) != 0) { 928 vm_page_dirty(fs.m); 929 vm_pager_page_unswapped(fs.m); 930 } 931 } 932 933 /* 934 * Page had better still be busy 935 */ 936 KASSERT(fs.m->oflags & VPO_BUSY, 937 ("vm_fault: page %p not busy!", fs.m)); 938 /* 939 * Page must be completely valid or it is not fit to 940 * map into user space. vm_pager_get_pages() ensures this. 941 */ 942 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 943 ("vm_fault: page %p partially invalid", fs.m)); 944 VM_OBJECT_UNLOCK(fs.object); 945 946 /* 947 * Put this page into the physical map. We had to do the unlock above 948 * because pmap_enter() may sleep. We don't put the page 949 * back on the active queue until later so that the pageout daemon 950 * won't find it (yet). 951 */ 952 pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired); 953 if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0) 954 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); 955 VM_OBJECT_LOCK(fs.object); 956 vm_page_lock(fs.m); 957 958 /* 959 * If the page is not wired down, then put it where the pageout daemon 960 * can find it. 961 */ 962 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 963 if (wired) 964 vm_page_wire(fs.m); 965 else 966 vm_page_unwire(fs.m, 1); 967 } else 968 vm_page_activate(fs.m); 969 if (m_hold != NULL) { 970 *m_hold = fs.m; 971 vm_page_hold(fs.m); 972 } 973 vm_page_unlock(fs.m); 974 vm_page_wakeup(fs.m); 975 976 /* 977 * Unlock everything, and return 978 */ 979 unlock_and_deallocate(&fs); 980 if (hardfault) 981 curthread->td_ru.ru_majflt++; 982 else 983 curthread->td_ru.ru_minflt++; 984 985 return (KERN_SUCCESS); 986} 987 988/* 989 * Speed up the reclamation of up to "distance" pages that precede the 990 * faulting pindex within the first object of the shadow chain. 991 */ 992static void 993vm_fault_cache_behind(const struct faultstate *fs, int distance) 994{ 995 vm_object_t first_object, object; 996 vm_page_t m, m_prev; 997 vm_pindex_t pindex; 998 999 object = fs->object; 1000 VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); 1001 first_object = fs->first_object; 1002 if (first_object != object) { 1003 if (!VM_OBJECT_TRYLOCK(first_object)) { 1004 VM_OBJECT_UNLOCK(object); 1005 VM_OBJECT_LOCK(first_object); 1006 VM_OBJECT_LOCK(object); 1007 } 1008 } 1009 if (first_object->type != OBJT_DEVICE && 1010 first_object->type != OBJT_PHYS && first_object->type != OBJT_SG) { 1011 if (fs->first_pindex < distance) 1012 pindex = 0; 1013 else 1014 pindex = fs->first_pindex - distance; 1015 if (pindex < OFF_TO_IDX(fs->entry->offset)) 1016 pindex = OFF_TO_IDX(fs->entry->offset); 1017 m = first_object != object ? fs->first_m : fs->m; 1018 KASSERT((m->oflags & VPO_BUSY) != 0, 1019 ("vm_fault_cache_behind: page %p is not busy", m)); 1020 m_prev = vm_page_prev(m); 1021 while ((m = m_prev) != NULL && m->pindex >= pindex && 1022 m->valid == VM_PAGE_BITS_ALL) { 1023 m_prev = vm_page_prev(m); 1024 if (m->busy != 0 || (m->oflags & VPO_BUSY) != 0) 1025 continue; 1026 vm_page_lock(m); 1027 if (m->hold_count == 0 && m->wire_count == 0) { 1028 pmap_remove_all(m); 1029 vm_page_aflag_clear(m, PGA_REFERENCED); 1030 if (m->dirty != 0) 1031 vm_page_deactivate(m); 1032 else 1033 vm_page_cache(m); 1034 } 1035 vm_page_unlock(m); 1036 } 1037 } 1038 if (first_object != object) 1039 VM_OBJECT_UNLOCK(first_object); 1040} 1041 1042/* 1043 * vm_fault_prefault provides a quick way of clustering 1044 * pagefaults into a processes address space. It is a "cousin" 1045 * of vm_map_pmap_enter, except it runs at page fault time instead 1046 * of mmap time. 1047 */ 1048static void 1049vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) 1050{ 1051 int i; 1052 vm_offset_t addr, starta; 1053 vm_pindex_t pindex; 1054 vm_page_t m; 1055 vm_object_t object; 1056 1057 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 1058 return; 1059 1060 object = entry->object.vm_object; 1061 1062 starta = addra - PFBAK * PAGE_SIZE; 1063 if (starta < entry->start) { 1064 starta = entry->start; 1065 } else if (starta > addra) { 1066 starta = 0; 1067 } 1068 1069 for (i = 0; i < PAGEORDER_SIZE; i++) { 1070 vm_object_t backing_object, lobject; 1071 1072 addr = addra + prefault_pageorder[i]; 1073 if (addr > addra + (PFFOR * PAGE_SIZE)) 1074 addr = 0; 1075 1076 if (addr < starta || addr >= entry->end) 1077 continue; 1078 1079 if (!pmap_is_prefaultable(pmap, addr)) 1080 continue; 1081 1082 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1083 lobject = object; 1084 VM_OBJECT_LOCK(lobject); 1085 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1086 lobject->type == OBJT_DEFAULT && 1087 (backing_object = lobject->backing_object) != NULL) { 1088 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1089 0, ("vm_fault_prefault: unaligned object offset")); 1090 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1091 VM_OBJECT_LOCK(backing_object); 1092 VM_OBJECT_UNLOCK(lobject); 1093 lobject = backing_object; 1094 } 1095 /* 1096 * give-up when a page is not in memory 1097 */ 1098 if (m == NULL) { 1099 VM_OBJECT_UNLOCK(lobject); 1100 break; 1101 } 1102 if (m->valid == VM_PAGE_BITS_ALL && 1103 (m->flags & PG_FICTITIOUS) == 0) 1104 pmap_enter_quick(pmap, addr, m, entry->protection); 1105 VM_OBJECT_UNLOCK(lobject); 1106 } 1107} 1108 1109/* 1110 * Hold each of the physical pages that are mapped by the specified range of 1111 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid 1112 * and allow the specified types of access, "prot". If all of the implied 1113 * pages are successfully held, then the number of held pages is returned 1114 * together with pointers to those pages in the array "ma". However, if any 1115 * of the pages cannot be held, -1 is returned. 1116 */ 1117int 1118vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len, 1119 vm_prot_t prot, vm_page_t *ma, int max_count) 1120{ 1121 vm_offset_t end, va; 1122 vm_page_t *mp; 1123 int count; 1124 boolean_t pmap_failed; 1125 1126 if (len == 0) 1127 return (0); 1128 end = round_page(addr + len); 1129 addr = trunc_page(addr); 1130 1131 /* 1132 * Check for illegal addresses. 1133 */ 1134 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map)) 1135 return (-1); 1136 1137 if (atop(end - addr) > max_count) 1138 panic("vm_fault_quick_hold_pages: count > max_count"); 1139 count = atop(end - addr); 1140 1141 /* 1142 * Most likely, the physical pages are resident in the pmap, so it is 1143 * faster to try pmap_extract_and_hold() first. 1144 */ 1145 pmap_failed = FALSE; 1146 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) { 1147 *mp = pmap_extract_and_hold(map->pmap, va, prot); 1148 if (*mp == NULL) 1149 pmap_failed = TRUE; 1150 else if ((prot & VM_PROT_WRITE) != 0 && 1151 (*mp)->dirty != VM_PAGE_BITS_ALL) { 1152 /* 1153 * Explicitly dirty the physical page. Otherwise, the 1154 * caller's changes may go unnoticed because they are 1155 * performed through an unmanaged mapping or by a DMA 1156 * operation. 1157 * 1158 * The object lock is not held here. 1159 * See vm_page_clear_dirty_mask(). 1160 */ 1161 vm_page_dirty(*mp); 1162 } 1163 } 1164 if (pmap_failed) { 1165 /* 1166 * One or more pages could not be held by the pmap. Either no 1167 * page was mapped at the specified virtual address or that 1168 * mapping had insufficient permissions. Attempt to fault in 1169 * and hold these pages. 1170 */ 1171 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) 1172 if (*mp == NULL && vm_fault_hold(map, va, prot, 1173 VM_FAULT_NORMAL, mp) != KERN_SUCCESS) 1174 goto error; 1175 } 1176 return (count); 1177error: 1178 for (mp = ma; mp < ma + count; mp++) 1179 if (*mp != NULL) { 1180 vm_page_lock(*mp); 1181 vm_page_unhold(*mp); 1182 vm_page_unlock(*mp); 1183 } 1184 return (-1); 1185} 1186 1187/* 1188 * vm_fault_wire: 1189 * 1190 * Wire down a range of virtual addresses in a map. 1191 */ 1192int 1193vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1194 boolean_t fictitious) 1195{ 1196 vm_offset_t va; 1197 int rv; 1198 1199 /* 1200 * We simulate a fault to get the page and enter it in the physical 1201 * map. For user wiring, we only ask for read access on currently 1202 * read-only sections. 1203 */ 1204 for (va = start; va < end; va += PAGE_SIZE) { 1205 rv = vm_fault(map, va, VM_PROT_NONE, VM_FAULT_CHANGE_WIRING); 1206 if (rv) { 1207 if (va != start) 1208 vm_fault_unwire(map, start, va, fictitious); 1209 return (rv); 1210 } 1211 } 1212 return (KERN_SUCCESS); 1213} 1214 1215/* 1216 * vm_fault_unwire: 1217 * 1218 * Unwire a range of virtual addresses in a map. 1219 */ 1220void 1221vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1222 boolean_t fictitious) 1223{ 1224 vm_paddr_t pa; 1225 vm_offset_t va; 1226 vm_page_t m; 1227 pmap_t pmap; 1228 1229 pmap = vm_map_pmap(map); 1230 1231 /* 1232 * Since the pages are wired down, we must be able to get their 1233 * mappings from the physical map system. 1234 */ 1235 for (va = start; va < end; va += PAGE_SIZE) { 1236 pa = pmap_extract(pmap, va); 1237 if (pa != 0) { 1238 pmap_change_wiring(pmap, va, FALSE); 1239 if (!fictitious) { 1240 m = PHYS_TO_VM_PAGE(pa); 1241 vm_page_lock(m); 1242 vm_page_unwire(m, TRUE); 1243 vm_page_unlock(m); 1244 } 1245 } 1246 } 1247} 1248 1249/* 1250 * Routine: 1251 * vm_fault_copy_entry 1252 * Function: 1253 * Create new shadow object backing dst_entry with private copy of 1254 * all underlying pages. When src_entry is equal to dst_entry, 1255 * function implements COW for wired-down map entry. Otherwise, 1256 * it forks wired entry into dst_map. 1257 * 1258 * In/out conditions: 1259 * The source and destination maps must be locked for write. 1260 * The source map entry must be wired down (or be a sharing map 1261 * entry corresponding to a main map entry that is wired down). 1262 */ 1263void 1264vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1265 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1266 vm_ooffset_t *fork_charge) 1267{ 1268 vm_object_t backing_object, dst_object, object, src_object; 1269 vm_pindex_t dst_pindex, pindex, src_pindex; 1270 vm_prot_t access, prot; 1271 vm_offset_t vaddr; 1272 vm_page_t dst_m; 1273 vm_page_t src_m; 1274 boolean_t upgrade; 1275 1276#ifdef lint 1277 src_map++; 1278#endif /* lint */ 1279 1280 upgrade = src_entry == dst_entry; 1281 1282 src_object = src_entry->object.vm_object; 1283 src_pindex = OFF_TO_IDX(src_entry->offset); 1284 1285 /* 1286 * Create the top-level object for the destination entry. (Doesn't 1287 * actually shadow anything - we copy the pages directly.) 1288 */ 1289 dst_object = vm_object_allocate(OBJT_DEFAULT, 1290 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1291#if VM_NRESERVLEVEL > 0 1292 dst_object->flags |= OBJ_COLORED; 1293 dst_object->pg_color = atop(dst_entry->start); 1294#endif 1295 1296 VM_OBJECT_LOCK(dst_object); 1297 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1298 ("vm_fault_copy_entry: vm_object not NULL")); 1299 dst_entry->object.vm_object = dst_object; 1300 dst_entry->offset = 0; 1301 dst_object->charge = dst_entry->end - dst_entry->start; 1302 if (fork_charge != NULL) { 1303 KASSERT(dst_entry->cred == NULL, 1304 ("vm_fault_copy_entry: leaked swp charge")); 1305 dst_object->cred = curthread->td_ucred; 1306 crhold(dst_object->cred); 1307 *fork_charge += dst_object->charge; 1308 } else { 1309 dst_object->cred = dst_entry->cred; 1310 dst_entry->cred = NULL; 1311 } 1312 access = prot = dst_entry->protection; 1313 /* 1314 * If not an upgrade, then enter the mappings in the pmap as 1315 * read and/or execute accesses. Otherwise, enter them as 1316 * write accesses. 1317 * 1318 * A writeable large page mapping is only created if all of 1319 * the constituent small page mappings are modified. Marking 1320 * PTEs as modified on inception allows promotion to happen 1321 * without taking potentially large number of soft faults. 1322 */ 1323 if (!upgrade) 1324 access &= ~VM_PROT_WRITE; 1325 1326 /* 1327 * Loop through all of the virtual pages within the entry's 1328 * range, copying each page from the source object to the 1329 * destination object. Since the source is wired, those pages 1330 * must exist. In contrast, the destination is pageable. 1331 * Since the destination object does share any backing storage 1332 * with the source object, all of its pages must be dirtied, 1333 * regardless of whether they can be written. 1334 */ 1335 for (vaddr = dst_entry->start, dst_pindex = 0; 1336 vaddr < dst_entry->end; 1337 vaddr += PAGE_SIZE, dst_pindex++) { 1338 1339 /* 1340 * Allocate a page in the destination object. 1341 */ 1342 do { 1343 dst_m = vm_page_alloc(dst_object, dst_pindex, 1344 VM_ALLOC_NORMAL); 1345 if (dst_m == NULL) { 1346 VM_OBJECT_UNLOCK(dst_object); 1347 VM_WAIT; 1348 VM_OBJECT_LOCK(dst_object); 1349 } 1350 } while (dst_m == NULL); 1351 1352 /* 1353 * Find the page in the source object, and copy it in. 1354 * Because the source is wired down, the page will be 1355 * in memory. 1356 */ 1357 VM_OBJECT_LOCK(src_object); 1358 object = src_object; 1359 pindex = src_pindex + dst_pindex; 1360 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1361 (backing_object = object->backing_object) != NULL) { 1362 /* 1363 * Unless the source mapping is read-only or 1364 * it is presently being upgraded from 1365 * read-only, the first object in the shadow 1366 * chain should provide all of the pages. In 1367 * other words, this loop body should never be 1368 * executed when the source mapping is already 1369 * read/write. 1370 */ 1371 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 || 1372 upgrade, 1373 ("vm_fault_copy_entry: main object missing page")); 1374 1375 VM_OBJECT_LOCK(backing_object); 1376 pindex += OFF_TO_IDX(object->backing_object_offset); 1377 VM_OBJECT_UNLOCK(object); 1378 object = backing_object; 1379 } 1380 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing")); 1381 pmap_copy_page(src_m, dst_m); 1382 VM_OBJECT_UNLOCK(object); 1383 dst_m->valid = VM_PAGE_BITS_ALL; 1384 dst_m->dirty = VM_PAGE_BITS_ALL; 1385 VM_OBJECT_UNLOCK(dst_object); 1386 1387 /* 1388 * Enter it in the pmap. If a wired, copy-on-write 1389 * mapping is being replaced by a write-enabled 1390 * mapping, then wire that new mapping. 1391 */ 1392 pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade); 1393 1394 /* 1395 * Mark it no longer busy, and put it on the active list. 1396 */ 1397 VM_OBJECT_LOCK(dst_object); 1398 1399 if (upgrade) { 1400 vm_page_lock(src_m); 1401 vm_page_unwire(src_m, 0); 1402 vm_page_unlock(src_m); 1403 1404 vm_page_lock(dst_m); 1405 vm_page_wire(dst_m); 1406 vm_page_unlock(dst_m); 1407 } else { 1408 vm_page_lock(dst_m); 1409 vm_page_activate(dst_m); 1410 vm_page_unlock(dst_m); 1411 } 1412 vm_page_wakeup(dst_m); 1413 } 1414 VM_OBJECT_UNLOCK(dst_object); 1415 if (upgrade) { 1416 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1417 vm_object_deallocate(src_object); 1418 } 1419} 1420 1421 1422/* 1423 * This routine checks around the requested page for other pages that 1424 * might be able to be faulted in. This routine brackets the viable 1425 * pages for the pages to be paged in. 1426 * 1427 * Inputs: 1428 * m, rbehind, rahead 1429 * 1430 * Outputs: 1431 * marray (array of vm_page_t), reqpage (index of requested page) 1432 * 1433 * Return value: 1434 * number of pages in marray 1435 */ 1436static int 1437vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1438 vm_page_t m; 1439 int rbehind; 1440 int rahead; 1441 vm_page_t *marray; 1442 int *reqpage; 1443{ 1444 int i,j; 1445 vm_object_t object; 1446 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1447 vm_page_t rtm; 1448 int cbehind, cahead; 1449 1450 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1451 1452 object = m->object; 1453 pindex = m->pindex; 1454 cbehind = cahead = 0; 1455 1456 /* 1457 * if the requested page is not available, then give up now 1458 */ 1459 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1460 return 0; 1461 } 1462 1463 if ((cbehind == 0) && (cahead == 0)) { 1464 *reqpage = 0; 1465 marray[0] = m; 1466 return 1; 1467 } 1468 1469 if (rahead > cahead) { 1470 rahead = cahead; 1471 } 1472 1473 if (rbehind > cbehind) { 1474 rbehind = cbehind; 1475 } 1476 1477 /* 1478 * scan backward for the read behind pages -- in memory 1479 */ 1480 if (pindex > 0) { 1481 if (rbehind > pindex) { 1482 rbehind = pindex; 1483 startpindex = 0; 1484 } else { 1485 startpindex = pindex - rbehind; 1486 } 1487 1488 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1489 rtm->pindex >= startpindex) 1490 startpindex = rtm->pindex + 1; 1491 1492 /* tpindex is unsigned; beware of numeric underflow. */ 1493 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1494 tpindex < pindex; i++, tpindex--) { 1495 1496 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1497 VM_ALLOC_IFNOTCACHED); 1498 if (rtm == NULL) { 1499 /* 1500 * Shift the allocated pages to the 1501 * beginning of the array. 1502 */ 1503 for (j = 0; j < i; j++) { 1504 marray[j] = marray[j + tpindex + 1 - 1505 startpindex]; 1506 } 1507 break; 1508 } 1509 1510 marray[tpindex - startpindex] = rtm; 1511 } 1512 } else { 1513 startpindex = 0; 1514 i = 0; 1515 } 1516 1517 marray[i] = m; 1518 /* page offset of the required page */ 1519 *reqpage = i; 1520 1521 tpindex = pindex + 1; 1522 i++; 1523 1524 /* 1525 * scan forward for the read ahead pages 1526 */ 1527 endpindex = tpindex + rahead; 1528 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1529 endpindex = rtm->pindex; 1530 if (endpindex > object->size) 1531 endpindex = object->size; 1532 1533 for (; tpindex < endpindex; i++, tpindex++) { 1534 1535 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1536 VM_ALLOC_IFNOTCACHED); 1537 if (rtm == NULL) { 1538 break; 1539 } 1540 1541 marray[i] = rtm; 1542 } 1543 1544 /* return number of pages */ 1545 return i; 1546} 1547 1548/* 1549 * Block entry into the machine-independent layer's page fault handler by 1550 * the calling thread. Subsequent calls to vm_fault() by that thread will 1551 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of 1552 * spurious page faults. 1553 */ 1554int 1555vm_fault_disable_pagefaults(void) 1556{ 1557 1558 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR)); 1559} 1560 1561void 1562vm_fault_enable_pagefaults(int save) 1563{ 1564 1565 curthread_pflags_restore(save); 1566} 1567