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