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_vm.h" 78 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/lock.h> 83 #include <sys/mutex.h> 84 #include <sys/proc.h> 85 #include <sys/resourcevar.h> 86 #include <sys/sysctl.h> 87 #include <sys/vmmeter.h> 88 #include <sys/vnode.h> 89 90 #include <vm/vm.h> 91 #include <vm/vm_param.h> 92 #include <vm/pmap.h> 93 #include <vm/vm_map.h> 94 #include <vm/vm_object.h> 95 #include <vm/vm_page.h> 96 #include <vm/vm_pageout.h> 97 #include <vm/vm_kern.h> 98 #include <vm/vm_pager.h> 99 #include <vm/vm_extern.h> 100 101 #include <sys/mount.h> /* XXX Temporary for VFS_LOCK_GIANT() */ 102 103 #define PFBAK 4 104 #define PFFOR 4 105 #define PAGEORDER_SIZE (PFBAK+PFFOR) 106 107 static int prefault_pageorder[] = { 108 -1 * PAGE_SIZE, 1 * PAGE_SIZE, 109 -2 * PAGE_SIZE, 2 * PAGE_SIZE, 110 -3 * PAGE_SIZE, 3 * PAGE_SIZE, 111 -4 * PAGE_SIZE, 4 * PAGE_SIZE 112 }; 113 114 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); 115 static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t); 116 117 #define VM_FAULT_READ_AHEAD 8 118 #define VM_FAULT_READ_BEHIND 7 119 #define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1) 120 121 struct faultstate { 122 vm_page_t m; 123 vm_object_t object; 124 vm_pindex_t pindex; 125 vm_page_t first_m; 126 vm_object_t first_object; 127 vm_pindex_t first_pindex; 128 vm_map_t map; 129 vm_map_entry_t entry; 130 int lookup_still_valid; 131 struct vnode *vp; 132 int vfslocked; 133 }; 134 135 static inline void 136 release_page(struct faultstate *fs) 137 { 138 139 vm_page_wakeup(fs->m); 140 vm_page_lock(fs->m); 141 vm_page_deactivate(fs->m); 142 vm_page_unlock(fs->m); 143 fs->m = NULL; 144 } 145 146 static inline void 147 unlock_map(struct faultstate *fs) 148 { 149 150 if (fs->lookup_still_valid) { 151 vm_map_lookup_done(fs->map, fs->entry); 152 fs->lookup_still_valid = FALSE; 153 } 154 } 155 156 static void 157 unlock_and_deallocate(struct faultstate *fs) 158 { 159 160 vm_object_pip_wakeup(fs->object); 161 VM_OBJECT_UNLOCK(fs->object); 162 if (fs->object != fs->first_object) { 163 VM_OBJECT_LOCK(fs->first_object); 164 vm_page_lock(fs->first_m); 165 vm_page_free(fs->first_m); 166 vm_page_unlock(fs->first_m); 167 vm_object_pip_wakeup(fs->first_object); 168 VM_OBJECT_UNLOCK(fs->first_object); 169 fs->first_m = NULL; 170 } 171 vm_object_deallocate(fs->first_object); 172 unlock_map(fs); 173 if (fs->vp != NULL) { 174 vput(fs->vp); 175 fs->vp = NULL; 176 } 177 VFS_UNLOCK_GIANT(fs->vfslocked); 178 fs->vfslocked = 0; 179 } 180 181 /* 182 * TRYPAGER - used by vm_fault to calculate whether the pager for the 183 * current object *might* contain the page. 184 * 185 * default objects are zero-fill, there is no real pager. 186 */ 187 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 188 ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 || wired)) 189 190 /* 191 * vm_fault: 192 * 193 * Handle a page fault occurring at the given address, 194 * requiring the given permissions, in the map specified. 195 * If successful, the page is inserted into the 196 * associated physical map. 197 * 198 * NOTE: the given address should be truncated to the 199 * proper page address. 200 * 201 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 202 * a standard error specifying why the fault is fatal is returned. 203 * 204 * The map in question must be referenced, and remains so. 205 * Caller may hold no locks. 206 */ 207 int 208 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 209 int fault_flags) 210 { 211 212 if ((curthread->td_pflags & TDP_NOFAULTING) != 0) 213 return (KERN_PROTECTION_FAILURE); 214 return (vm_fault_hold(map, vaddr, fault_type, fault_flags, NULL)); 215 } 216 217 int 218 vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 219 int fault_flags, vm_page_t *m_hold) 220 { 221 vm_prot_t prot; 222 int is_first_object_locked, result; 223 boolean_t growstack, wired; 224 int map_generation; 225 vm_object_t next_object; 226 vm_page_t marray[VM_FAULT_READ], mt, mt_prev; 227 int hardfault; 228 int faultcount, ahead, behind, alloc_req; 229 struct faultstate fs; 230 struct vnode *vp; 231 int locked, error; 232 233 hardfault = 0; 234 growstack = TRUE; 235 PCPU_INC(cnt.v_vm_faults); 236 fs.vp = NULL; 237 fs.vfslocked = 0; 238 faultcount = behind = 0; 239 240 RetryFault:; 241 242 /* 243 * Find the backing store object and offset into it to begin the 244 * search. 245 */ 246 fs.map = map; 247 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 248 &fs.first_object, &fs.first_pindex, &prot, &wired); 249 if (result != KERN_SUCCESS) { 250 if (growstack && result == KERN_INVALID_ADDRESS && 251 map != kernel_map) { 252 result = vm_map_growstack(curproc, vaddr); 253 if (result != KERN_SUCCESS) 254 return (KERN_FAILURE); 255 growstack = FALSE; 256 goto RetryFault; 257 } 258 return (result); 259 } 260 261 map_generation = fs.map->timestamp; 262 263 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 264 panic("vm_fault: fault on nofault entry, addr: %lx", 265 (u_long)vaddr); 266 } 267 268 /* 269 * Make a reference to this object to prevent its disposal while we 270 * are messing with it. Once we have the reference, the map is free 271 * to be diddled. Since objects reference their shadows (and copies), 272 * they will stay around as well. 273 * 274 * Bump the paging-in-progress count to prevent size changes (e.g. 275 * truncation operations) during I/O. This must be done after 276 * obtaining the vnode lock in order to avoid possible deadlocks. 277 */ 278 VM_OBJECT_LOCK(fs.first_object); 279 vm_object_reference_locked(fs.first_object); 280 vm_object_pip_add(fs.first_object, 1); 281 282 fs.lookup_still_valid = TRUE; 283 284 if (wired) 285 fault_type = prot | (fault_type & VM_PROT_COPY); 286 287 fs.first_m = NULL; 288 289 /* 290 * Search for the page at object/offset. 291 */ 292 fs.object = fs.first_object; 293 fs.pindex = fs.first_pindex; 294 while (TRUE) { 295 /* 296 * If the object is dead, we stop here 297 */ 298 if (fs.object->flags & OBJ_DEAD) { 299 unlock_and_deallocate(&fs); 300 return (KERN_PROTECTION_FAILURE); 301 } 302 303 /* 304 * See if page is resident 305 */ 306 fs.m = vm_page_lookup(fs.object, fs.pindex); 307 if (fs.m != NULL) { 308 /* 309 * check for page-based copy on write. 310 * We check fs.object == fs.first_object so 311 * as to ensure the legacy COW mechanism is 312 * used when the page in question is part of 313 * a shadow object. Otherwise, vm_page_cowfault() 314 * removes the page from the backing object, 315 * which is not what we want. 316 */ 317 vm_page_lock(fs.m); 318 if ((fs.m->cow) && 319 (fault_type & VM_PROT_WRITE) && 320 (fs.object == fs.first_object)) { 321 vm_page_cowfault(fs.m); 322 unlock_and_deallocate(&fs); 323 goto RetryFault; 324 } 325 326 /* 327 * Wait/Retry if the page is busy. We have to do this 328 * if the page is busy via either VPO_BUSY or 329 * vm_page_t->busy because the vm_pager may be using 330 * vm_page_t->busy for pageouts ( and even pageins if 331 * it is the vnode pager ), and we could end up trying 332 * to pagein and pageout the same page simultaneously. 333 * 334 * We can theoretically allow the busy case on a read 335 * fault if the page is marked valid, but since such 336 * pages are typically already pmap'd, putting that 337 * special case in might be more effort then it is 338 * worth. We cannot under any circumstances mess 339 * around with a vm_page_t->busy page except, perhaps, 340 * to pmap it. 341 */ 342 if ((fs.m->oflags & VPO_BUSY) || fs.m->busy) { 343 /* 344 * Reference the page before unlocking and 345 * sleeping so that the page daemon is less 346 * likely to reclaim it. 347 */ 348 vm_page_lock_queues(); 349 vm_page_flag_set(fs.m, PG_REFERENCED); 350 vm_page_unlock_queues(); 351 vm_page_unlock(fs.m); 352 if (fs.object != fs.first_object) { 353 if (!VM_OBJECT_TRYLOCK( 354 fs.first_object)) { 355 VM_OBJECT_UNLOCK(fs.object); 356 VM_OBJECT_LOCK(fs.first_object); 357 VM_OBJECT_LOCK(fs.object); 358 } 359 vm_page_lock(fs.first_m); 360 vm_page_free(fs.first_m); 361 vm_page_unlock(fs.first_m); 362 vm_object_pip_wakeup(fs.first_object); 363 VM_OBJECT_UNLOCK(fs.first_object); 364 fs.first_m = NULL; 365 } 366 unlock_map(&fs); 367 if (fs.m == vm_page_lookup(fs.object, 368 fs.pindex)) { 369 vm_page_sleep_if_busy(fs.m, TRUE, 370 "vmpfw"); 371 } 372 vm_object_pip_wakeup(fs.object); 373 VM_OBJECT_UNLOCK(fs.object); 374 PCPU_INC(cnt.v_intrans); 375 vm_object_deallocate(fs.first_object); 376 goto RetryFault; 377 } 378 vm_pageq_remove(fs.m); 379 vm_page_unlock(fs.m); 380 381 /* 382 * Mark page busy for other processes, and the 383 * pagedaemon. If it still isn't completely valid 384 * (readable), jump to readrest, else break-out ( we 385 * found the page ). 386 */ 387 vm_page_busy(fs.m); 388 if (fs.m->valid != VM_PAGE_BITS_ALL) 389 goto readrest; 390 break; 391 } 392 393 /* 394 * Page is not resident, If this is the search termination 395 * or the pager might contain the page, allocate a new page. 396 */ 397 if (TRYPAGER || fs.object == fs.first_object) { 398 if (fs.pindex >= fs.object->size) { 399 unlock_and_deallocate(&fs); 400 return (KERN_PROTECTION_FAILURE); 401 } 402 403 /* 404 * Allocate a new page for this object/offset pair. 405 * 406 * Unlocked read of the p_flag is harmless. At 407 * worst, the P_KILLED might be not observed 408 * there, and allocation can fail, causing 409 * restart and new reading of the p_flag. 410 */ 411 fs.m = NULL; 412 if (!vm_page_count_severe() || P_KILLED(curproc)) { 413 #if VM_NRESERVLEVEL > 0 414 if ((fs.object->flags & OBJ_COLORED) == 0) { 415 fs.object->flags |= OBJ_COLORED; 416 fs.object->pg_color = atop(vaddr) - 417 fs.pindex; 418 } 419 #endif 420 alloc_req = P_KILLED(curproc) ? 421 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 422 if (fs.object->type != OBJT_VNODE && 423 fs.object->backing_object == NULL) 424 alloc_req |= VM_ALLOC_ZERO; 425 fs.m = vm_page_alloc(fs.object, fs.pindex, 426 alloc_req); 427 } 428 if (fs.m == NULL) { 429 unlock_and_deallocate(&fs); 430 VM_WAITPFAULT; 431 goto RetryFault; 432 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 433 break; 434 } 435 436 readrest: 437 /* 438 * We have found a valid page or we have allocated a new page. 439 * The page thus may not be valid or may not be entirely 440 * valid. 441 * 442 * Attempt to fault-in the page if there is a chance that the 443 * pager has it, and potentially fault in additional pages 444 * at the same time. 445 */ 446 if (TRYPAGER) { 447 int rv; 448 int reqpage = 0; 449 u_char behavior = vm_map_entry_behavior(fs.entry); 450 451 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 452 P_KILLED(curproc)) { 453 ahead = 0; 454 behind = 0; 455 } else { 456 behind = (vaddr - fs.entry->start) >> PAGE_SHIFT; 457 if (behind > VM_FAULT_READ_BEHIND) 458 behind = VM_FAULT_READ_BEHIND; 459 460 ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1; 461 if (ahead > VM_FAULT_READ_AHEAD) 462 ahead = VM_FAULT_READ_AHEAD; 463 } 464 is_first_object_locked = FALSE; 465 if ((behavior == MAP_ENTRY_BEHAV_SEQUENTIAL || 466 (behavior != MAP_ENTRY_BEHAV_RANDOM && 467 fs.pindex >= fs.entry->lastr && 468 fs.pindex < fs.entry->lastr + VM_FAULT_READ)) && 469 (fs.first_object == fs.object || 470 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object))) && 471 fs.first_object->type != OBJT_DEVICE && 472 fs.first_object->type != OBJT_PHYS && 473 fs.first_object->type != OBJT_SG) { 474 vm_pindex_t firstpindex; 475 476 if (fs.first_pindex < 2 * VM_FAULT_READ) 477 firstpindex = 0; 478 else 479 firstpindex = fs.first_pindex - 2 * VM_FAULT_READ; 480 mt = fs.first_object != fs.object ? 481 fs.first_m : fs.m; 482 KASSERT(mt != NULL, ("vm_fault: missing mt")); 483 KASSERT((mt->oflags & VPO_BUSY) != 0, 484 ("vm_fault: mt %p not busy", mt)); 485 mt_prev = vm_page_prev(mt); 486 487 /* 488 * note: partially valid pages cannot be 489 * included in the lookahead - NFS piecemeal 490 * writes will barf on it badly. 491 */ 492 while ((mt = mt_prev) != NULL && 493 mt->pindex >= firstpindex && 494 mt->valid == VM_PAGE_BITS_ALL) { 495 mt_prev = vm_page_prev(mt); 496 if (mt->busy || 497 (mt->oflags & VPO_BUSY)) 498 continue; 499 vm_page_lock(mt); 500 if (mt->hold_count || 501 mt->wire_count) { 502 vm_page_unlock(mt); 503 continue; 504 } 505 pmap_remove_all(mt); 506 if (mt->dirty != 0) 507 vm_page_deactivate(mt); 508 else 509 vm_page_cache(mt); 510 vm_page_unlock(mt); 511 } 512 ahead += behind; 513 behind = 0; 514 } 515 if (is_first_object_locked) 516 VM_OBJECT_UNLOCK(fs.first_object); 517 518 /* 519 * Call the pager to retrieve the data, if any, after 520 * releasing the lock on the map. We hold a ref on 521 * fs.object and the pages are VPO_BUSY'd. 522 */ 523 unlock_map(&fs); 524 525 vnode_lock: 526 if (fs.object->type == OBJT_VNODE) { 527 vp = fs.object->handle; 528 if (vp == fs.vp) 529 goto vnode_locked; 530 else if (fs.vp != NULL) { 531 vput(fs.vp); 532 fs.vp = NULL; 533 } 534 locked = VOP_ISLOCKED(vp); 535 536 if (VFS_NEEDSGIANT(vp->v_mount) && !fs.vfslocked) { 537 fs.vfslocked = 1; 538 if (!mtx_trylock(&Giant)) { 539 VM_OBJECT_UNLOCK(fs.object); 540 mtx_lock(&Giant); 541 VM_OBJECT_LOCK(fs.object); 542 goto vnode_lock; 543 } 544 } 545 if (locked != LK_EXCLUSIVE) 546 locked = LK_SHARED; 547 /* Do not sleep for vnode lock while fs.m is busy */ 548 error = vget(vp, locked | LK_CANRECURSE | 549 LK_NOWAIT, curthread); 550 if (error != 0) { 551 int vfslocked; 552 553 vfslocked = fs.vfslocked; 554 fs.vfslocked = 0; /* Keep Giant */ 555 vhold(vp); 556 release_page(&fs); 557 unlock_and_deallocate(&fs); 558 error = vget(vp, locked | LK_RETRY | 559 LK_CANRECURSE, curthread); 560 vdrop(vp); 561 fs.vp = vp; 562 fs.vfslocked = vfslocked; 563 KASSERT(error == 0, 564 ("vm_fault: vget failed")); 565 goto RetryFault; 566 } 567 fs.vp = vp; 568 } 569 vnode_locked: 570 KASSERT(fs.vp == NULL || !fs.map->system_map, 571 ("vm_fault: vnode-backed object mapped by system map")); 572 573 /* 574 * now we find out if any other pages should be paged 575 * in at this time this routine checks to see if the 576 * pages surrounding this fault reside in the same 577 * object as the page for this fault. If they do, 578 * then they are faulted in also into the object. The 579 * array "marray" returned contains an array of 580 * vm_page_t structs where one of them is the 581 * vm_page_t passed to the routine. The reqpage 582 * return value is the index into the marray for the 583 * vm_page_t passed to the routine. 584 * 585 * fs.m plus the additional pages are VPO_BUSY'd. 586 */ 587 faultcount = vm_fault_additional_pages( 588 fs.m, behind, ahead, marray, &reqpage); 589 590 rv = faultcount ? 591 vm_pager_get_pages(fs.object, marray, faultcount, 592 reqpage) : VM_PAGER_FAIL; 593 594 if (rv == VM_PAGER_OK) { 595 /* 596 * Found the page. Leave it busy while we play 597 * with it. 598 */ 599 600 /* 601 * Relookup in case pager changed page. Pager 602 * is responsible for disposition of old page 603 * if moved. 604 */ 605 fs.m = vm_page_lookup(fs.object, fs.pindex); 606 if (!fs.m) { 607 unlock_and_deallocate(&fs); 608 goto RetryFault; 609 } 610 611 hardfault++; 612 break; /* break to PAGE HAS BEEN FOUND */ 613 } 614 /* 615 * Remove the bogus page (which does not exist at this 616 * object/offset); before doing so, we must get back 617 * our object lock to preserve our invariant. 618 * 619 * Also wake up any other process that may want to bring 620 * in this page. 621 * 622 * If this is the top-level object, we must leave the 623 * busy page to prevent another process from rushing 624 * past us, and inserting the page in that object at 625 * the same time that we are. 626 */ 627 if (rv == VM_PAGER_ERROR) 628 printf("vm_fault: pager read error, pid %d (%s)\n", 629 curproc->p_pid, curproc->p_comm); 630 /* 631 * Data outside the range of the pager or an I/O error 632 */ 633 /* 634 * XXX - the check for kernel_map is a kludge to work 635 * around having the machine panic on a kernel space 636 * fault w/ I/O error. 637 */ 638 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 639 (rv == VM_PAGER_BAD)) { 640 vm_page_lock(fs.m); 641 vm_page_free(fs.m); 642 vm_page_unlock(fs.m); 643 fs.m = NULL; 644 unlock_and_deallocate(&fs); 645 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 646 } 647 if (fs.object != fs.first_object) { 648 vm_page_lock(fs.m); 649 vm_page_free(fs.m); 650 vm_page_unlock(fs.m); 651 fs.m = NULL; 652 /* 653 * XXX - we cannot just fall out at this 654 * point, m has been freed and is invalid! 655 */ 656 } 657 } 658 659 /* 660 * We get here if the object has default pager (or unwiring) 661 * or the pager doesn't have the page. 662 */ 663 if (fs.object == fs.first_object) 664 fs.first_m = fs.m; 665 666 /* 667 * Move on to the next object. Lock the next object before 668 * unlocking the current one. 669 */ 670 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 671 next_object = fs.object->backing_object; 672 if (next_object == NULL) { 673 /* 674 * If there's no object left, fill the page in the top 675 * object with zeros. 676 */ 677 if (fs.object != fs.first_object) { 678 vm_object_pip_wakeup(fs.object); 679 VM_OBJECT_UNLOCK(fs.object); 680 681 fs.object = fs.first_object; 682 fs.pindex = fs.first_pindex; 683 fs.m = fs.first_m; 684 VM_OBJECT_LOCK(fs.object); 685 } 686 fs.first_m = NULL; 687 688 /* 689 * Zero the page if necessary and mark it valid. 690 */ 691 if ((fs.m->flags & PG_ZERO) == 0) { 692 pmap_zero_page(fs.m); 693 } else { 694 PCPU_INC(cnt.v_ozfod); 695 } 696 PCPU_INC(cnt.v_zfod); 697 fs.m->valid = VM_PAGE_BITS_ALL; 698 break; /* break to PAGE HAS BEEN FOUND */ 699 } else { 700 KASSERT(fs.object != next_object, 701 ("object loop %p", next_object)); 702 VM_OBJECT_LOCK(next_object); 703 vm_object_pip_add(next_object, 1); 704 if (fs.object != fs.first_object) 705 vm_object_pip_wakeup(fs.object); 706 VM_OBJECT_UNLOCK(fs.object); 707 fs.object = next_object; 708 } 709 } 710 711 KASSERT((fs.m->oflags & VPO_BUSY) != 0, 712 ("vm_fault: not busy after main loop")); 713 714 /* 715 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 716 * is held.] 717 */ 718 719 /* 720 * If the page is being written, but isn't already owned by the 721 * top-level object, we have to copy it into a new page owned by the 722 * top-level object. 723 */ 724 if (fs.object != fs.first_object) { 725 /* 726 * We only really need to copy if we want to write it. 727 */ 728 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 729 /* 730 * This allows pages to be virtually copied from a 731 * backing_object into the first_object, where the 732 * backing object has no other refs to it, and cannot 733 * gain any more refs. Instead of a bcopy, we just 734 * move the page from the backing object to the 735 * first object. Note that we must mark the page 736 * dirty in the first object so that it will go out 737 * to swap when needed. 738 */ 739 is_first_object_locked = FALSE; 740 if ( 741 /* 742 * Only one shadow object 743 */ 744 (fs.object->shadow_count == 1) && 745 /* 746 * No COW refs, except us 747 */ 748 (fs.object->ref_count == 1) && 749 /* 750 * No one else can look this object up 751 */ 752 (fs.object->handle == NULL) && 753 /* 754 * No other ways to look the object up 755 */ 756 ((fs.object->type == OBJT_DEFAULT) || 757 (fs.object->type == OBJT_SWAP)) && 758 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) && 759 /* 760 * We don't chase down the shadow chain 761 */ 762 fs.object == fs.first_object->backing_object) { 763 /* 764 * get rid of the unnecessary page 765 */ 766 vm_page_lock(fs.first_m); 767 vm_page_free(fs.first_m); 768 vm_page_unlock(fs.first_m); 769 /* 770 * grab the page and put it into the 771 * process'es object. The page is 772 * automatically made dirty. 773 */ 774 vm_page_lock(fs.m); 775 vm_page_rename(fs.m, fs.first_object, fs.first_pindex); 776 vm_page_unlock(fs.m); 777 vm_page_busy(fs.m); 778 fs.first_m = fs.m; 779 fs.m = NULL; 780 PCPU_INC(cnt.v_cow_optim); 781 } else { 782 /* 783 * Oh, well, lets copy it. 784 */ 785 pmap_copy_page(fs.m, fs.first_m); 786 fs.first_m->valid = VM_PAGE_BITS_ALL; 787 if (wired && (fault_flags & 788 VM_FAULT_CHANGE_WIRING) == 0) { 789 vm_page_lock(fs.first_m); 790 vm_page_wire(fs.first_m); 791 vm_page_unlock(fs.first_m); 792 793 vm_page_lock(fs.m); 794 vm_page_unwire(fs.m, FALSE); 795 vm_page_unlock(fs.m); 796 } 797 /* 798 * We no longer need the old page or object. 799 */ 800 release_page(&fs); 801 } 802 /* 803 * fs.object != fs.first_object due to above 804 * conditional 805 */ 806 vm_object_pip_wakeup(fs.object); 807 VM_OBJECT_UNLOCK(fs.object); 808 /* 809 * Only use the new page below... 810 */ 811 fs.object = fs.first_object; 812 fs.pindex = fs.first_pindex; 813 fs.m = fs.first_m; 814 if (!is_first_object_locked) 815 VM_OBJECT_LOCK(fs.object); 816 PCPU_INC(cnt.v_cow_faults); 817 } else { 818 prot &= ~VM_PROT_WRITE; 819 } 820 } 821 822 /* 823 * We must verify that the maps have not changed since our last 824 * lookup. 825 */ 826 if (!fs.lookup_still_valid) { 827 vm_object_t retry_object; 828 vm_pindex_t retry_pindex; 829 vm_prot_t retry_prot; 830 831 if (!vm_map_trylock_read(fs.map)) { 832 release_page(&fs); 833 unlock_and_deallocate(&fs); 834 goto RetryFault; 835 } 836 fs.lookup_still_valid = TRUE; 837 if (fs.map->timestamp != map_generation) { 838 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 839 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 840 841 /* 842 * If we don't need the page any longer, put it on the inactive 843 * list (the easiest thing to do here). If no one needs it, 844 * pageout will grab it eventually. 845 */ 846 if (result != KERN_SUCCESS) { 847 release_page(&fs); 848 unlock_and_deallocate(&fs); 849 850 /* 851 * If retry of map lookup would have blocked then 852 * retry fault from start. 853 */ 854 if (result == KERN_FAILURE) 855 goto RetryFault; 856 return (result); 857 } 858 if ((retry_object != fs.first_object) || 859 (retry_pindex != fs.first_pindex)) { 860 release_page(&fs); 861 unlock_and_deallocate(&fs); 862 goto RetryFault; 863 } 864 865 /* 866 * Check whether the protection has changed or the object has 867 * been copied while we left the map unlocked. Changing from 868 * read to write permission is OK - we leave the page 869 * write-protected, and catch the write fault. Changing from 870 * write to read permission means that we can't mark the page 871 * write-enabled after all. 872 */ 873 prot &= retry_prot; 874 } 875 } 876 /* 877 * If the page was filled by a pager, update the map entry's 878 * last read offset. Since the pager does not return the 879 * actual set of pages that it read, this update is based on 880 * the requested set. Typically, the requested and actual 881 * sets are the same. 882 * 883 * XXX The following assignment modifies the map 884 * without holding a write lock on it. 885 */ 886 if (hardfault) 887 fs.entry->lastr = fs.pindex + faultcount - behind; 888 889 if ((prot & VM_PROT_WRITE) != 0 || 890 (fault_flags & VM_FAULT_DIRTY) != 0) { 891 vm_object_set_writeable_dirty(fs.object); 892 893 /* 894 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 895 * if the page is already dirty to prevent data written with 896 * the expectation of being synced from not being synced. 897 * Likewise if this entry does not request NOSYNC then make 898 * sure the page isn't marked NOSYNC. Applications sharing 899 * data should use the same flags to avoid ping ponging. 900 */ 901 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 902 if (fs.m->dirty == 0) 903 fs.m->oflags |= VPO_NOSYNC; 904 } else { 905 fs.m->oflags &= ~VPO_NOSYNC; 906 } 907 908 /* 909 * If the fault is a write, we know that this page is being 910 * written NOW so dirty it explicitly to save on 911 * pmap_is_modified() calls later. 912 * 913 * Also tell the backing pager, if any, that it should remove 914 * any swap backing since the page is now dirty. 915 */ 916 if (((fault_type & VM_PROT_WRITE) != 0 && 917 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) || 918 (fault_flags & VM_FAULT_DIRTY) != 0) { 919 vm_page_dirty(fs.m); 920 vm_pager_page_unswapped(fs.m); 921 } 922 } 923 924 /* 925 * Page had better still be busy 926 */ 927 KASSERT(fs.m->oflags & VPO_BUSY, 928 ("vm_fault: page %p not busy!", fs.m)); 929 /* 930 * Page must be completely valid or it is not fit to 931 * map into user space. vm_pager_get_pages() ensures this. 932 */ 933 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 934 ("vm_fault: page %p partially invalid", fs.m)); 935 VM_OBJECT_UNLOCK(fs.object); 936 937 /* 938 * Put this page into the physical map. We had to do the unlock above 939 * because pmap_enter() may sleep. We don't put the page 940 * back on the active queue until later so that the pageout daemon 941 * won't find it (yet). 942 */ 943 pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired); 944 if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0) 945 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); 946 VM_OBJECT_LOCK(fs.object); 947 vm_page_lock(fs.m); 948 949 /* 950 * If the page is not wired down, then put it where the pageout daemon 951 * can find it. 952 */ 953 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 954 if (wired) 955 vm_page_wire(fs.m); 956 else 957 vm_page_unwire(fs.m, 1); 958 } else 959 vm_page_activate(fs.m); 960 if (m_hold != NULL) { 961 *m_hold = fs.m; 962 vm_page_hold(fs.m); 963 } 964 vm_page_unlock(fs.m); 965 vm_page_wakeup(fs.m); 966 967 /* 968 * Unlock everything, and return 969 */ 970 unlock_and_deallocate(&fs); 971 if (hardfault) 972 curthread->td_ru.ru_majflt++; 973 else 974 curthread->td_ru.ru_minflt++; 975 976 return (KERN_SUCCESS); 977 } 978 979 /* 980 * vm_fault_prefault provides a quick way of clustering 981 * pagefaults into a processes address space. It is a "cousin" 982 * of vm_map_pmap_enter, except it runs at page fault time instead 983 * of mmap time. 984 */ 985 static void 986 vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) 987 { 988 int i; 989 vm_offset_t addr, starta; 990 vm_pindex_t pindex; 991 vm_page_t m; 992 vm_object_t object; 993 994 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 995 return; 996 997 object = entry->object.vm_object; 998 999 starta = addra - PFBAK * PAGE_SIZE; 1000 if (starta < entry->start) { 1001 starta = entry->start; 1002 } else if (starta > addra) { 1003 starta = 0; 1004 } 1005 1006 for (i = 0; i < PAGEORDER_SIZE; i++) { 1007 vm_object_t backing_object, lobject; 1008 1009 addr = addra + prefault_pageorder[i]; 1010 if (addr > addra + (PFFOR * PAGE_SIZE)) 1011 addr = 0; 1012 1013 if (addr < starta || addr >= entry->end) 1014 continue; 1015 1016 if (!pmap_is_prefaultable(pmap, addr)) 1017 continue; 1018 1019 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1020 lobject = object; 1021 VM_OBJECT_LOCK(lobject); 1022 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1023 lobject->type == OBJT_DEFAULT && 1024 (backing_object = lobject->backing_object) != NULL) { 1025 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1026 0, ("vm_fault_prefault: unaligned object offset")); 1027 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1028 VM_OBJECT_LOCK(backing_object); 1029 VM_OBJECT_UNLOCK(lobject); 1030 lobject = backing_object; 1031 } 1032 /* 1033 * give-up when a page is not in memory 1034 */ 1035 if (m == NULL) { 1036 VM_OBJECT_UNLOCK(lobject); 1037 break; 1038 } 1039 if (m->valid == VM_PAGE_BITS_ALL && 1040 (m->flags & PG_FICTITIOUS) == 0) 1041 pmap_enter_quick(pmap, addr, m, entry->protection); 1042 VM_OBJECT_UNLOCK(lobject); 1043 } 1044 } 1045 1046 /* 1047 * Hold each of the physical pages that are mapped by the specified range of 1048 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid 1049 * and allow the specified types of access, "prot". If all of the implied 1050 * pages are successfully held, then the number of held pages is returned 1051 * together with pointers to those pages in the array "ma". However, if any 1052 * of the pages cannot be held, -1 is returned. 1053 */ 1054 int 1055 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len, 1056 vm_prot_t prot, vm_page_t *ma, int max_count) 1057 { 1058 vm_offset_t end, va; 1059 vm_page_t *mp; 1060 int count; 1061 boolean_t pmap_failed; 1062 1063 if (len == 0) 1064 return (0); 1065 end = round_page(addr + len); 1066 addr = trunc_page(addr); 1067 1068 /* 1069 * Check for illegal addresses. 1070 */ 1071 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map)) 1072 return (-1); 1073 1074 count = howmany(end - addr, PAGE_SIZE); 1075 if (count > max_count) 1076 panic("vm_fault_quick_hold_pages: count > max_count"); 1077 1078 /* 1079 * Most likely, the physical pages are resident in the pmap, so it is 1080 * faster to try pmap_extract_and_hold() first. 1081 */ 1082 pmap_failed = FALSE; 1083 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) { 1084 *mp = pmap_extract_and_hold(map->pmap, va, prot); 1085 if (*mp == NULL) 1086 pmap_failed = TRUE; 1087 else if ((prot & VM_PROT_WRITE) != 0 && 1088 (*mp)->dirty != VM_PAGE_BITS_ALL) { 1089 /* 1090 * Explicitly dirty the physical page. Otherwise, the 1091 * caller's changes may go unnoticed because they are 1092 * performed through an unmanaged mapping or by a DMA 1093 * operation. 1094 * 1095 * The object lock is not held here. Therefore, like 1096 * a pmap operation, the page queues lock may be 1097 * required in order to call vm_page_dirty(). See 1098 * vm_page_clear_dirty_mask(). 1099 */ 1100 #if defined(__amd64__) || defined(__i386__) || defined(__ia64__) 1101 vm_page_dirty(*mp); 1102 #else 1103 vm_page_lock_queues(); 1104 vm_page_dirty(*mp); 1105 vm_page_unlock_queues(); 1106 #endif 1107 } 1108 } 1109 if (pmap_failed) { 1110 /* 1111 * One or more pages could not be held by the pmap. Either no 1112 * page was mapped at the specified virtual address or that 1113 * mapping had insufficient permissions. Attempt to fault in 1114 * and hold these pages. 1115 */ 1116 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) 1117 if (*mp == NULL && vm_fault_hold(map, va, prot, 1118 VM_FAULT_NORMAL, mp) != KERN_SUCCESS) 1119 goto error; 1120 } 1121 return (count); 1122 error: 1123 for (mp = ma; mp < ma + count; mp++) 1124 if (*mp != NULL) { 1125 vm_page_lock(*mp); 1126 vm_page_unhold(*mp); 1127 vm_page_unlock(*mp); 1128 } 1129 return (-1); 1130 } 1131 1132 /* 1133 * vm_fault_wire: 1134 * 1135 * Wire down a range of virtual addresses in a map. 1136 */ 1137 int 1138 vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1139 boolean_t fictitious) 1140 { 1141 vm_offset_t va; 1142 int rv; 1143 1144 /* 1145 * We simulate a fault to get the page and enter it in the physical 1146 * map. For user wiring, we only ask for read access on currently 1147 * read-only sections. 1148 */ 1149 for (va = start; va < end; va += PAGE_SIZE) { 1150 rv = vm_fault(map, va, VM_PROT_NONE, VM_FAULT_CHANGE_WIRING); 1151 if (rv) { 1152 if (va != start) 1153 vm_fault_unwire(map, start, va, fictitious); 1154 return (rv); 1155 } 1156 } 1157 return (KERN_SUCCESS); 1158 } 1159 1160 /* 1161 * vm_fault_unwire: 1162 * 1163 * Unwire a range of virtual addresses in a map. 1164 */ 1165 void 1166 vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1167 boolean_t fictitious) 1168 { 1169 vm_paddr_t pa; 1170 vm_offset_t va; 1171 vm_page_t m; 1172 pmap_t pmap; 1173 1174 pmap = vm_map_pmap(map); 1175 1176 /* 1177 * Since the pages are wired down, we must be able to get their 1178 * mappings from the physical map system. 1179 */ 1180 for (va = start; va < end; va += PAGE_SIZE) { 1181 pa = pmap_extract(pmap, va); 1182 if (pa != 0) { 1183 pmap_change_wiring(pmap, va, FALSE); 1184 if (!fictitious) { 1185 m = PHYS_TO_VM_PAGE(pa); 1186 vm_page_lock(m); 1187 vm_page_unwire(m, TRUE); 1188 vm_page_unlock(m); 1189 } 1190 } 1191 } 1192 } 1193 1194 /* 1195 * Routine: 1196 * vm_fault_copy_entry 1197 * Function: 1198 * Create new shadow object backing dst_entry with private copy of 1199 * all underlying pages. When src_entry is equal to dst_entry, 1200 * function implements COW for wired-down map entry. Otherwise, 1201 * it forks wired entry into dst_map. 1202 * 1203 * In/out conditions: 1204 * The source and destination maps must be locked for write. 1205 * The source map entry must be wired down (or be a sharing map 1206 * entry corresponding to a main map entry that is wired down). 1207 */ 1208 void 1209 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1210 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1211 vm_ooffset_t *fork_charge) 1212 { 1213 vm_object_t backing_object, dst_object, object, src_object; 1214 vm_pindex_t dst_pindex, pindex, src_pindex; 1215 vm_prot_t access, prot; 1216 vm_offset_t vaddr; 1217 vm_page_t dst_m; 1218 vm_page_t src_m; 1219 boolean_t src_readonly, upgrade; 1220 1221 #ifdef lint 1222 src_map++; 1223 #endif /* lint */ 1224 1225 upgrade = src_entry == dst_entry; 1226 1227 src_object = src_entry->object.vm_object; 1228 src_pindex = OFF_TO_IDX(src_entry->offset); 1229 src_readonly = (src_entry->protection & VM_PROT_WRITE) == 0; 1230 1231 /* 1232 * Create the top-level object for the destination entry. (Doesn't 1233 * actually shadow anything - we copy the pages directly.) 1234 */ 1235 dst_object = vm_object_allocate(OBJT_DEFAULT, 1236 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1237 #if VM_NRESERVLEVEL > 0 1238 dst_object->flags |= OBJ_COLORED; 1239 dst_object->pg_color = atop(dst_entry->start); 1240 #endif 1241 1242 VM_OBJECT_LOCK(dst_object); 1243 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1244 ("vm_fault_copy_entry: vm_object not NULL")); 1245 dst_entry->object.vm_object = dst_object; 1246 dst_entry->offset = 0; 1247 dst_object->charge = dst_entry->end - dst_entry->start; 1248 if (fork_charge != NULL) { 1249 KASSERT(dst_entry->cred == NULL, 1250 ("vm_fault_copy_entry: leaked swp charge")); 1251 dst_object->cred = curthread->td_ucred; 1252 crhold(dst_object->cred); 1253 *fork_charge += dst_object->charge; 1254 } else { 1255 dst_object->cred = dst_entry->cred; 1256 dst_entry->cred = NULL; 1257 } 1258 access = prot = dst_entry->protection; 1259 /* 1260 * If not an upgrade, then enter the mappings in the pmap as 1261 * read and/or execute accesses. Otherwise, enter them as 1262 * write accesses. 1263 * 1264 * A writeable large page mapping is only created if all of 1265 * the constituent small page mappings are modified. Marking 1266 * PTEs as modified on inception allows promotion to happen 1267 * without taking potentially large number of soft faults. 1268 */ 1269 if (!upgrade) 1270 access &= ~VM_PROT_WRITE; 1271 1272 /* 1273 * Loop through all of the pages in the entry's range, copying each 1274 * one from the source object (it should be there) to the destination 1275 * object. 1276 */ 1277 for (vaddr = dst_entry->start, dst_pindex = 0; 1278 vaddr < dst_entry->end; 1279 vaddr += PAGE_SIZE, dst_pindex++) { 1280 1281 /* 1282 * Allocate a page in the destination object. 1283 */ 1284 do { 1285 dst_m = vm_page_alloc(dst_object, dst_pindex, 1286 VM_ALLOC_NORMAL); 1287 if (dst_m == NULL) { 1288 VM_OBJECT_UNLOCK(dst_object); 1289 VM_WAIT; 1290 VM_OBJECT_LOCK(dst_object); 1291 } 1292 } while (dst_m == NULL); 1293 1294 /* 1295 * Find the page in the source object, and copy it in. 1296 * (Because the source is wired down, the page will be in 1297 * memory.) 1298 */ 1299 VM_OBJECT_LOCK(src_object); 1300 object = src_object; 1301 pindex = src_pindex + dst_pindex; 1302 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1303 src_readonly && 1304 (backing_object = object->backing_object) != NULL) { 1305 /* 1306 * Allow fallback to backing objects if we are reading. 1307 */ 1308 VM_OBJECT_LOCK(backing_object); 1309 pindex += OFF_TO_IDX(object->backing_object_offset); 1310 VM_OBJECT_UNLOCK(object); 1311 object = backing_object; 1312 } 1313 if (src_m == NULL) 1314 panic("vm_fault_copy_wired: page missing"); 1315 pmap_copy_page(src_m, dst_m); 1316 VM_OBJECT_UNLOCK(object); 1317 dst_m->valid = VM_PAGE_BITS_ALL; 1318 VM_OBJECT_UNLOCK(dst_object); 1319 1320 /* 1321 * Enter it in the pmap. If a wired, copy-on-write 1322 * mapping is being replaced by a write-enabled 1323 * mapping, then wire that new mapping. 1324 */ 1325 pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade); 1326 1327 /* 1328 * Mark it no longer busy, and put it on the active list. 1329 */ 1330 VM_OBJECT_LOCK(dst_object); 1331 1332 if (upgrade) { 1333 vm_page_lock(src_m); 1334 vm_page_unwire(src_m, 0); 1335 vm_page_unlock(src_m); 1336 1337 vm_page_lock(dst_m); 1338 vm_page_wire(dst_m); 1339 vm_page_unlock(dst_m); 1340 } else { 1341 vm_page_lock(dst_m); 1342 vm_page_activate(dst_m); 1343 vm_page_unlock(dst_m); 1344 } 1345 vm_page_wakeup(dst_m); 1346 } 1347 VM_OBJECT_UNLOCK(dst_object); 1348 if (upgrade) { 1349 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1350 vm_object_deallocate(src_object); 1351 } 1352 } 1353 1354 1355 /* 1356 * This routine checks around the requested page for other pages that 1357 * might be able to be faulted in. This routine brackets the viable 1358 * pages for the pages to be paged in. 1359 * 1360 * Inputs: 1361 * m, rbehind, rahead 1362 * 1363 * Outputs: 1364 * marray (array of vm_page_t), reqpage (index of requested page) 1365 * 1366 * Return value: 1367 * number of pages in marray 1368 */ 1369 static int 1370 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1371 vm_page_t m; 1372 int rbehind; 1373 int rahead; 1374 vm_page_t *marray; 1375 int *reqpage; 1376 { 1377 int i,j; 1378 vm_object_t object; 1379 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1380 vm_page_t rtm; 1381 int cbehind, cahead; 1382 1383 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1384 1385 object = m->object; 1386 pindex = m->pindex; 1387 cbehind = cahead = 0; 1388 1389 /* 1390 * if the requested page is not available, then give up now 1391 */ 1392 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1393 return 0; 1394 } 1395 1396 if ((cbehind == 0) && (cahead == 0)) { 1397 *reqpage = 0; 1398 marray[0] = m; 1399 return 1; 1400 } 1401 1402 if (rahead > cahead) { 1403 rahead = cahead; 1404 } 1405 1406 if (rbehind > cbehind) { 1407 rbehind = cbehind; 1408 } 1409 1410 /* 1411 * scan backward for the read behind pages -- in memory 1412 */ 1413 if (pindex > 0) { 1414 if (rbehind > pindex) { 1415 rbehind = pindex; 1416 startpindex = 0; 1417 } else { 1418 startpindex = pindex - rbehind; 1419 } 1420 1421 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1422 rtm->pindex >= startpindex) 1423 startpindex = rtm->pindex + 1; 1424 1425 /* tpindex is unsigned; beware of numeric underflow. */ 1426 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1427 tpindex < pindex; i++, tpindex--) { 1428 1429 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1430 VM_ALLOC_IFNOTCACHED); 1431 if (rtm == NULL) { 1432 /* 1433 * Shift the allocated pages to the 1434 * beginning of the array. 1435 */ 1436 for (j = 0; j < i; j++) { 1437 marray[j] = marray[j + tpindex + 1 - 1438 startpindex]; 1439 } 1440 break; 1441 } 1442 1443 marray[tpindex - startpindex] = rtm; 1444 } 1445 } else { 1446 startpindex = 0; 1447 i = 0; 1448 } 1449 1450 marray[i] = m; 1451 /* page offset of the required page */ 1452 *reqpage = i; 1453 1454 tpindex = pindex + 1; 1455 i++; 1456 1457 /* 1458 * scan forward for the read ahead pages 1459 */ 1460 endpindex = tpindex + rahead; 1461 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1462 endpindex = rtm->pindex; 1463 if (endpindex > object->size) 1464 endpindex = object->size; 1465 1466 for (; tpindex < endpindex; i++, tpindex++) { 1467 1468 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1469 VM_ALLOC_IFNOTCACHED); 1470 if (rtm == NULL) { 1471 break; 1472 } 1473 1474 marray[i] = rtm; 1475 } 1476 1477 /* return number of pages */ 1478 return i; 1479 } 1480 1481 int 1482 vm_fault_disable_pagefaults(void) 1483 { 1484 1485 return (curthread_pflags_set(TDP_NOFAULTING)); 1486 } 1487 1488 void 1489 vm_fault_enable_pagefaults(int save) 1490 { 1491 1492 curthread_pflags_restore(save); 1493 } 1494