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 vm_page_t m; 241 int locked, error; 242 243 hardfault = 0; 244 growstack = TRUE; 245 PCPU_INC(cnt.v_vm_faults); 246 fs.vp = NULL; 247 faultcount = reqpage = 0; 248 249 RetryFault:; 250 251 /* 252 * Find the backing store object and offset into it to begin the 253 * search. 254 */ 255 fs.map = map; 256 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 257 &fs.first_object, &fs.first_pindex, &prot, &wired); 258 if (result != KERN_SUCCESS) { 259 if (growstack && result == KERN_INVALID_ADDRESS && 260 map != kernel_map) { 261 result = vm_map_growstack(curproc, vaddr); 262 if (result != KERN_SUCCESS) 263 return (KERN_FAILURE); 264 growstack = FALSE; 265 goto RetryFault; 266 } 267 return (result); 268 } 269 270 map_generation = fs.map->timestamp; 271 272 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 273 if ((curthread->td_pflags & TDP_DEVMEMIO) != 0) { 274 vm_map_unlock_read(fs.map); 275 return (KERN_FAILURE); 276 } 277 panic("vm_fault: fault on nofault entry, addr: %lx", 278 (u_long)vaddr); 279 } 280 281 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION && 282 fs.entry->wiring_thread != curthread) { 283 vm_map_unlock_read(fs.map); 284 vm_map_lock(fs.map); 285 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) && 286 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) { 287 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP; 288 vm_map_unlock_and_wait(fs.map, 0); 289 } else 290 vm_map_unlock(fs.map); 291 goto RetryFault; 292 } 293 294 if (wired) 295 fault_type = prot | (fault_type & VM_PROT_COPY); 296 297 if (fs.vp == NULL /* avoid locked vnode leak */ && 298 (fault_flags & (VM_FAULT_CHANGE_WIRING | VM_FAULT_DIRTY)) == 0 && 299 /* avoid calling vm_object_set_writeable_dirty() */ 300 ((prot & VM_PROT_WRITE) == 0 || 301 fs.first_object->type != OBJT_VNODE || 302 (fs.first_object->flags & OBJ_MIGHTBEDIRTY) != 0)) { 303 VM_OBJECT_RLOCK(fs.first_object); 304 if ((prot & VM_PROT_WRITE) != 0 && 305 fs.first_object->type == OBJT_VNODE && 306 (fs.first_object->flags & OBJ_MIGHTBEDIRTY) == 0) 307 goto fast_failed; 308 m = vm_page_lookup(fs.first_object, fs.first_pindex); 309 /* A busy page can be mapped for read|execute access. */ 310 if (m == NULL || ((prot & VM_PROT_WRITE) != 0 && 311 vm_page_busied(m)) || m->valid != VM_PAGE_BITS_ALL) 312 goto fast_failed; 313 result = pmap_enter(fs.map->pmap, vaddr, m, prot, 314 fault_type | PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED : 315 0), 0); 316 if (result != KERN_SUCCESS) 317 goto fast_failed; 318 if (m_hold != NULL) { 319 *m_hold = m; 320 vm_page_lock(m); 321 vm_page_hold(m); 322 vm_page_unlock(m); 323 } 324 if ((fault_type & VM_PROT_WRITE) != 0 && 325 (m->oflags & VPO_UNMANAGED) == 0) { 326 vm_page_dirty(m); 327 vm_pager_page_unswapped(m); 328 } 329 VM_OBJECT_RUNLOCK(fs.first_object); 330 if (!wired) 331 vm_fault_prefault(&fs, vaddr, 0, 0); 332 vm_map_lookup_done(fs.map, fs.entry); 333 curthread->td_ru.ru_minflt++; 334 return (KERN_SUCCESS); 335 fast_failed: 336 if (!VM_OBJECT_TRYUPGRADE(fs.first_object)) { 337 VM_OBJECT_RUNLOCK(fs.first_object); 338 VM_OBJECT_WLOCK(fs.first_object); 339 } 340 } else { 341 VM_OBJECT_WLOCK(fs.first_object); 342 } 343 344 /* 345 * Make a reference to this object to prevent its disposal while we 346 * are messing with it. Once we have the reference, the map is free 347 * to be diddled. Since objects reference their shadows (and copies), 348 * they will stay around as well. 349 * 350 * Bump the paging-in-progress count to prevent size changes (e.g. 351 * truncation operations) during I/O. This must be done after 352 * obtaining the vnode lock in order to avoid possible deadlocks. 353 */ 354 vm_object_reference_locked(fs.first_object); 355 vm_object_pip_add(fs.first_object, 1); 356 357 fs.lookup_still_valid = TRUE; 358 359 fs.first_m = NULL; 360 361 /* 362 * Search for the page at object/offset. 363 */ 364 fs.object = fs.first_object; 365 fs.pindex = fs.first_pindex; 366 while (TRUE) { 367 /* 368 * If the object is dead, we stop here 369 */ 370 if (fs.object->flags & OBJ_DEAD) { 371 unlock_and_deallocate(&fs); 372 return (KERN_PROTECTION_FAILURE); 373 } 374 375 /* 376 * See if page is resident 377 */ 378 fs.m = vm_page_lookup(fs.object, fs.pindex); 379 if (fs.m != NULL) { 380 /* 381 * Wait/Retry if the page is busy. We have to do this 382 * if the page is either exclusive or shared busy 383 * because the vm_pager may be using read busy for 384 * pageouts (and even pageins if it is the vnode 385 * pager), and we could end up trying to pagein and 386 * pageout the same page simultaneously. 387 * 388 * We can theoretically allow the busy case on a read 389 * fault if the page is marked valid, but since such 390 * pages are typically already pmap'd, putting that 391 * special case in might be more effort then it is 392 * worth. We cannot under any circumstances mess 393 * around with a shared busied page except, perhaps, 394 * to pmap it. 395 */ 396 if (vm_page_busied(fs.m)) { 397 /* 398 * Reference the page before unlocking and 399 * sleeping so that the page daemon is less 400 * likely to reclaim it. 401 */ 402 vm_page_aflag_set(fs.m, PGA_REFERENCED); 403 if (fs.object != fs.first_object) { 404 if (!VM_OBJECT_TRYWLOCK( 405 fs.first_object)) { 406 VM_OBJECT_WUNLOCK(fs.object); 407 VM_OBJECT_WLOCK(fs.first_object); 408 VM_OBJECT_WLOCK(fs.object); 409 } 410 vm_page_lock(fs.first_m); 411 vm_page_free(fs.first_m); 412 vm_page_unlock(fs.first_m); 413 vm_object_pip_wakeup(fs.first_object); 414 VM_OBJECT_WUNLOCK(fs.first_object); 415 fs.first_m = NULL; 416 } 417 unlock_map(&fs); 418 if (fs.m == vm_page_lookup(fs.object, 419 fs.pindex)) { 420 vm_page_sleep_if_busy(fs.m, "vmpfw"); 421 } 422 vm_object_pip_wakeup(fs.object); 423 VM_OBJECT_WUNLOCK(fs.object); 424 PCPU_INC(cnt.v_intrans); 425 vm_object_deallocate(fs.first_object); 426 goto RetryFault; 427 } 428 vm_page_lock(fs.m); 429 vm_page_remque(fs.m); 430 vm_page_unlock(fs.m); 431 432 /* 433 * Mark page busy for other processes, and the 434 * pagedaemon. If it still isn't completely valid 435 * (readable), jump to readrest, else break-out ( we 436 * found the page ). 437 */ 438 vm_page_xbusy(fs.m); 439 if (fs.m->valid != VM_PAGE_BITS_ALL) 440 goto readrest; 441 break; 442 } 443 444 /* 445 * Page is not resident, If this is the search termination 446 * or the pager might contain the page, allocate a new page. 447 */ 448 if (TRYPAGER || fs.object == fs.first_object) { 449 if (fs.pindex >= fs.object->size) { 450 unlock_and_deallocate(&fs); 451 return (KERN_PROTECTION_FAILURE); 452 } 453 454 /* 455 * Allocate a new page for this object/offset pair. 456 * 457 * Unlocked read of the p_flag is harmless. At 458 * worst, the P_KILLED might be not observed 459 * there, and allocation can fail, causing 460 * restart and new reading of the p_flag. 461 */ 462 fs.m = NULL; 463 if (!vm_page_count_severe() || P_KILLED(curproc)) { 464 #if VM_NRESERVLEVEL > 0 465 if ((fs.object->flags & OBJ_COLORED) == 0) { 466 fs.object->flags |= OBJ_COLORED; 467 fs.object->pg_color = atop(vaddr) - 468 fs.pindex; 469 } 470 #endif 471 alloc_req = P_KILLED(curproc) ? 472 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 473 if (fs.object->type != OBJT_VNODE && 474 fs.object->backing_object == NULL) 475 alloc_req |= VM_ALLOC_ZERO; 476 fs.m = vm_page_alloc(fs.object, fs.pindex, 477 alloc_req); 478 } 479 if (fs.m == NULL) { 480 unlock_and_deallocate(&fs); 481 VM_WAITPFAULT; 482 goto RetryFault; 483 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 484 break; 485 } 486 487 readrest: 488 /* 489 * We have found a valid page or we have allocated a new page. 490 * The page thus may not be valid or may not be entirely 491 * valid. 492 * 493 * Attempt to fault-in the page if there is a chance that the 494 * pager has it, and potentially fault in additional pages 495 * at the same time. 496 */ 497 if (TRYPAGER) { 498 int rv; 499 u_char behavior = vm_map_entry_behavior(fs.entry); 500 501 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 502 P_KILLED(curproc)) { 503 behind = 0; 504 ahead = 0; 505 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) { 506 behind = 0; 507 ahead = atop(fs.entry->end - vaddr) - 1; 508 if (ahead > VM_FAULT_READ_AHEAD_MAX) 509 ahead = VM_FAULT_READ_AHEAD_MAX; 510 if (fs.pindex == fs.entry->next_read) 511 vm_fault_cache_behind(&fs, 512 VM_FAULT_READ_MAX); 513 } else { 514 /* 515 * If this is a sequential page fault, then 516 * arithmetically increase the number of pages 517 * in the read-ahead window. Otherwise, reset 518 * the read-ahead window to its smallest size. 519 */ 520 behind = atop(vaddr - fs.entry->start); 521 if (behind > VM_FAULT_READ_BEHIND) 522 behind = VM_FAULT_READ_BEHIND; 523 ahead = atop(fs.entry->end - vaddr) - 1; 524 era = fs.entry->read_ahead; 525 if (fs.pindex == fs.entry->next_read) { 526 nera = era + behind; 527 if (nera > VM_FAULT_READ_AHEAD_MAX) 528 nera = VM_FAULT_READ_AHEAD_MAX; 529 behind = 0; 530 if (ahead > nera) 531 ahead = nera; 532 if (era == VM_FAULT_READ_AHEAD_MAX) 533 vm_fault_cache_behind(&fs, 534 VM_FAULT_CACHE_BEHIND); 535 } else if (ahead > VM_FAULT_READ_AHEAD_MIN) 536 ahead = VM_FAULT_READ_AHEAD_MIN; 537 if (era != ahead) 538 fs.entry->read_ahead = ahead; 539 } 540 541 /* 542 * Call the pager to retrieve the data, if any, after 543 * releasing the lock on the map. We hold a ref on 544 * fs.object and the pages are exclusive busied. 545 */ 546 unlock_map(&fs); 547 548 if (fs.object->type == OBJT_VNODE) { 549 vp = fs.object->handle; 550 if (vp == fs.vp) 551 goto vnode_locked; 552 else if (fs.vp != NULL) { 553 vput(fs.vp); 554 fs.vp = NULL; 555 } 556 locked = VOP_ISLOCKED(vp); 557 558 if (locked != LK_EXCLUSIVE) 559 locked = LK_SHARED; 560 /* Do not sleep for vnode lock while fs.m is busy */ 561 error = vget(vp, locked | LK_CANRECURSE | 562 LK_NOWAIT, curthread); 563 if (error != 0) { 564 vhold(vp); 565 release_page(&fs); 566 unlock_and_deallocate(&fs); 567 error = vget(vp, locked | LK_RETRY | 568 LK_CANRECURSE, curthread); 569 vdrop(vp); 570 fs.vp = vp; 571 KASSERT(error == 0, 572 ("vm_fault: vget failed")); 573 goto RetryFault; 574 } 575 fs.vp = vp; 576 } 577 vnode_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 exclusive busied. 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_WUNLOCK(fs.object); 688 689 fs.object = fs.first_object; 690 fs.pindex = fs.first_pindex; 691 fs.m = fs.first_m; 692 VM_OBJECT_WLOCK(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 /* Don't try to prefault neighboring pages. */ 707 faultcount = 1; 708 break; /* break to PAGE HAS BEEN FOUND */ 709 } else { 710 KASSERT(fs.object != next_object, 711 ("object loop %p", next_object)); 712 VM_OBJECT_WLOCK(next_object); 713 vm_object_pip_add(next_object, 1); 714 if (fs.object != fs.first_object) 715 vm_object_pip_wakeup(fs.object); 716 VM_OBJECT_WUNLOCK(fs.object); 717 fs.object = next_object; 718 } 719 } 720 721 vm_page_assert_xbusied(fs.m); 722 723 /* 724 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 725 * is held.] 726 */ 727 728 /* 729 * If the page is being written, but isn't already owned by the 730 * top-level object, we have to copy it into a new page owned by the 731 * top-level object. 732 */ 733 if (fs.object != fs.first_object) { 734 /* 735 * We only really need to copy if we want to write it. 736 */ 737 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 738 /* 739 * This allows pages to be virtually copied from a 740 * backing_object into the first_object, where the 741 * backing object has no other refs to it, and cannot 742 * gain any more refs. Instead of a bcopy, we just 743 * move the page from the backing object to the 744 * first object. Note that we must mark the page 745 * dirty in the first object so that it will go out 746 * to swap when needed. 747 */ 748 is_first_object_locked = FALSE; 749 if ( 750 /* 751 * Only one shadow object 752 */ 753 (fs.object->shadow_count == 1) && 754 /* 755 * No COW refs, except us 756 */ 757 (fs.object->ref_count == 1) && 758 /* 759 * No one else can look this object up 760 */ 761 (fs.object->handle == NULL) && 762 /* 763 * No other ways to look the object up 764 */ 765 ((fs.object->type == OBJT_DEFAULT) || 766 (fs.object->type == OBJT_SWAP)) && 767 (is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) && 768 /* 769 * We don't chase down the shadow chain 770 */ 771 fs.object == fs.first_object->backing_object) { 772 /* 773 * get rid of the unnecessary page 774 */ 775 vm_page_lock(fs.first_m); 776 vm_page_free(fs.first_m); 777 vm_page_unlock(fs.first_m); 778 /* 779 * grab the page and put it into the 780 * process'es object. The page is 781 * automatically made dirty. 782 */ 783 if (vm_page_rename(fs.m, fs.first_object, 784 fs.first_pindex)) { 785 unlock_and_deallocate(&fs); 786 goto RetryFault; 787 } 788 vm_page_xbusy(fs.m); 789 fs.first_m = fs.m; 790 fs.m = NULL; 791 PCPU_INC(cnt.v_cow_optim); 792 } else { 793 /* 794 * Oh, well, lets copy it. 795 */ 796 pmap_copy_page(fs.m, fs.first_m); 797 fs.first_m->valid = VM_PAGE_BITS_ALL; 798 if (wired && (fault_flags & 799 VM_FAULT_CHANGE_WIRING) == 0) { 800 vm_page_lock(fs.first_m); 801 vm_page_wire(fs.first_m); 802 vm_page_unlock(fs.first_m); 803 804 vm_page_lock(fs.m); 805 vm_page_unwire(fs.m, PQ_INACTIVE); 806 vm_page_unlock(fs.m); 807 } 808 /* 809 * We no longer need the old page or object. 810 */ 811 release_page(&fs); 812 } 813 /* 814 * fs.object != fs.first_object due to above 815 * conditional 816 */ 817 vm_object_pip_wakeup(fs.object); 818 VM_OBJECT_WUNLOCK(fs.object); 819 /* 820 * Only use the new page below... 821 */ 822 fs.object = fs.first_object; 823 fs.pindex = fs.first_pindex; 824 fs.m = fs.first_m; 825 if (!is_first_object_locked) 826 VM_OBJECT_WLOCK(fs.object); 827 PCPU_INC(cnt.v_cow_faults); 828 curthread->td_cow++; 829 } else { 830 prot &= ~VM_PROT_WRITE; 831 } 832 } 833 834 /* 835 * We must verify that the maps have not changed since our last 836 * lookup. 837 */ 838 if (!fs.lookup_still_valid) { 839 vm_object_t retry_object; 840 vm_pindex_t retry_pindex; 841 vm_prot_t retry_prot; 842 843 if (!vm_map_trylock_read(fs.map)) { 844 release_page(&fs); 845 unlock_and_deallocate(&fs); 846 goto RetryFault; 847 } 848 fs.lookup_still_valid = TRUE; 849 if (fs.map->timestamp != map_generation) { 850 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 851 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 852 853 /* 854 * If we don't need the page any longer, put it on the inactive 855 * list (the easiest thing to do here). If no one needs it, 856 * pageout will grab it eventually. 857 */ 858 if (result != KERN_SUCCESS) { 859 release_page(&fs); 860 unlock_and_deallocate(&fs); 861 862 /* 863 * If retry of map lookup would have blocked then 864 * retry fault from start. 865 */ 866 if (result == KERN_FAILURE) 867 goto RetryFault; 868 return (result); 869 } 870 if ((retry_object != fs.first_object) || 871 (retry_pindex != fs.first_pindex)) { 872 release_page(&fs); 873 unlock_and_deallocate(&fs); 874 goto RetryFault; 875 } 876 877 /* 878 * Check whether the protection has changed or the object has 879 * been copied while we left the map unlocked. Changing from 880 * read to write permission is OK - we leave the page 881 * write-protected, and catch the write fault. Changing from 882 * write to read permission means that we can't mark the page 883 * write-enabled after all. 884 */ 885 prot &= retry_prot; 886 } 887 } 888 /* 889 * If the page was filled by a pager, update the map entry's 890 * last read offset. Since the pager does not return the 891 * actual set of pages that it read, this update is based on 892 * the requested set. Typically, the requested and actual 893 * sets are the same. 894 * 895 * XXX The following assignment modifies the map 896 * without holding a write lock on it. 897 */ 898 if (hardfault) 899 fs.entry->next_read = fs.pindex + faultcount - reqpage; 900 901 if (((prot & VM_PROT_WRITE) != 0 || 902 (fault_flags & VM_FAULT_DIRTY) != 0) && 903 (fs.m->oflags & VPO_UNMANAGED) == 0) { 904 vm_object_set_writeable_dirty(fs.object); 905 906 /* 907 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 908 * if the page is already dirty to prevent data written with 909 * the expectation of being synced from not being synced. 910 * Likewise if this entry does not request NOSYNC then make 911 * sure the page isn't marked NOSYNC. Applications sharing 912 * data should use the same flags to avoid ping ponging. 913 */ 914 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 915 if (fs.m->dirty == 0) 916 fs.m->oflags |= VPO_NOSYNC; 917 } else { 918 fs.m->oflags &= ~VPO_NOSYNC; 919 } 920 921 /* 922 * If the fault is a write, we know that this page is being 923 * written NOW so dirty it explicitly to save on 924 * pmap_is_modified() calls later. 925 * 926 * Also tell the backing pager, if any, that it should remove 927 * any swap backing since the page is now dirty. 928 */ 929 if (((fault_type & VM_PROT_WRITE) != 0 && 930 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) || 931 (fault_flags & VM_FAULT_DIRTY) != 0) { 932 vm_page_dirty(fs.m); 933 vm_pager_page_unswapped(fs.m); 934 } 935 } 936 937 vm_page_assert_xbusied(fs.m); 938 939 /* 940 * Page must be completely valid or it is not fit to 941 * map into user space. vm_pager_get_pages() ensures this. 942 */ 943 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 944 ("vm_fault: page %p partially invalid", fs.m)); 945 VM_OBJECT_WUNLOCK(fs.object); 946 947 /* 948 * Put this page into the physical map. We had to do the unlock above 949 * because pmap_enter() may sleep. We don't put the page 950 * back on the active queue until later so that the pageout daemon 951 * won't find it (yet). 952 */ 953 pmap_enter(fs.map->pmap, vaddr, fs.m, prot, 954 fault_type | (wired ? PMAP_ENTER_WIRED : 0), 0); 955 if (faultcount != 1 && (fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && 956 wired == 0) 957 vm_fault_prefault(&fs, vaddr, faultcount, reqpage); 958 VM_OBJECT_WLOCK(fs.object); 959 vm_page_lock(fs.m); 960 961 /* 962 * If the page is not wired down, then put it where the pageout daemon 963 * can find it. 964 */ 965 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 966 if (wired) 967 vm_page_wire(fs.m); 968 else 969 vm_page_unwire(fs.m, PQ_ACTIVE); 970 } else 971 vm_page_activate(fs.m); 972 if (m_hold != NULL) { 973 *m_hold = fs.m; 974 vm_page_hold(fs.m); 975 } 976 vm_page_unlock(fs.m); 977 vm_page_xunbusy(fs.m); 978 979 /* 980 * Unlock everything, and return 981 */ 982 unlock_and_deallocate(&fs); 983 if (hardfault) { 984 PCPU_INC(cnt.v_io_faults); 985 curthread->td_ru.ru_majflt++; 986 } else 987 curthread->td_ru.ru_minflt++; 988 989 return (KERN_SUCCESS); 990 } 991 992 /* 993 * Speed up the reclamation of up to "distance" pages that precede the 994 * faulting pindex within the first object of the shadow chain. 995 */ 996 static void 997 vm_fault_cache_behind(const struct faultstate *fs, int distance) 998 { 999 vm_object_t first_object, object; 1000 vm_page_t m, m_prev; 1001 vm_pindex_t pindex; 1002 1003 object = fs->object; 1004 VM_OBJECT_ASSERT_WLOCKED(object); 1005 first_object = fs->first_object; 1006 if (first_object != object) { 1007 if (!VM_OBJECT_TRYWLOCK(first_object)) { 1008 VM_OBJECT_WUNLOCK(object); 1009 VM_OBJECT_WLOCK(first_object); 1010 VM_OBJECT_WLOCK(object); 1011 } 1012 } 1013 /* Neither fictitious nor unmanaged pages can be cached. */ 1014 if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) { 1015 if (fs->first_pindex < distance) 1016 pindex = 0; 1017 else 1018 pindex = fs->first_pindex - distance; 1019 if (pindex < OFF_TO_IDX(fs->entry->offset)) 1020 pindex = OFF_TO_IDX(fs->entry->offset); 1021 m = first_object != object ? fs->first_m : fs->m; 1022 vm_page_assert_xbusied(m); 1023 m_prev = vm_page_prev(m); 1024 while ((m = m_prev) != NULL && m->pindex >= pindex && 1025 m->valid == VM_PAGE_BITS_ALL) { 1026 m_prev = vm_page_prev(m); 1027 if (vm_page_busied(m)) 1028 continue; 1029 vm_page_lock(m); 1030 if (m->hold_count == 0 && m->wire_count == 0) { 1031 pmap_remove_all(m); 1032 vm_page_aflag_clear(m, PGA_REFERENCED); 1033 if (m->dirty != 0) 1034 vm_page_deactivate(m); 1035 else 1036 vm_page_cache(m); 1037 } 1038 vm_page_unlock(m); 1039 } 1040 } 1041 if (first_object != object) 1042 VM_OBJECT_WUNLOCK(first_object); 1043 } 1044 1045 /* 1046 * vm_fault_prefault provides a quick way of clustering 1047 * pagefaults into a processes address space. It is a "cousin" 1048 * of vm_map_pmap_enter, except it runs at page fault time instead 1049 * of mmap time. 1050 */ 1051 static void 1052 vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra, 1053 int faultcount, int reqpage) 1054 { 1055 pmap_t pmap; 1056 vm_map_entry_t entry; 1057 vm_object_t backing_object, lobject; 1058 vm_offset_t addr, starta; 1059 vm_pindex_t pindex; 1060 vm_page_t m; 1061 int backward, forward, i; 1062 1063 pmap = fs->map->pmap; 1064 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 1065 return; 1066 1067 if (faultcount > 0) { 1068 backward = reqpage; 1069 forward = faultcount - reqpage - 1; 1070 } else { 1071 backward = PFBAK; 1072 forward = PFFOR; 1073 } 1074 entry = fs->entry; 1075 1076 starta = addra - backward * PAGE_SIZE; 1077 if (starta < entry->start) { 1078 starta = entry->start; 1079 } else if (starta > addra) { 1080 starta = 0; 1081 } 1082 1083 /* 1084 * Generate the sequence of virtual addresses that are candidates for 1085 * prefaulting in an outward spiral from the faulting virtual address, 1086 * "addra". Specifically, the sequence is "addra - PAGE_SIZE", "addra 1087 * + PAGE_SIZE", "addra - 2 * PAGE_SIZE", "addra + 2 * PAGE_SIZE", ... 1088 * If the candidate address doesn't have a backing physical page, then 1089 * the loop immediately terminates. 1090 */ 1091 for (i = 0; i < 2 * imax(backward, forward); i++) { 1092 addr = addra + ((i >> 1) + 1) * ((i & 1) == 0 ? -PAGE_SIZE : 1093 PAGE_SIZE); 1094 if (addr > addra + forward * PAGE_SIZE) 1095 addr = 0; 1096 1097 if (addr < starta || addr >= entry->end) 1098 continue; 1099 1100 if (!pmap_is_prefaultable(pmap, addr)) 1101 continue; 1102 1103 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1104 lobject = entry->object.vm_object; 1105 VM_OBJECT_RLOCK(lobject); 1106 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1107 lobject->type == OBJT_DEFAULT && 1108 (backing_object = lobject->backing_object) != NULL) { 1109 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1110 0, ("vm_fault_prefault: unaligned object offset")); 1111 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1112 VM_OBJECT_RLOCK(backing_object); 1113 VM_OBJECT_RUNLOCK(lobject); 1114 lobject = backing_object; 1115 } 1116 if (m == NULL) { 1117 VM_OBJECT_RUNLOCK(lobject); 1118 break; 1119 } 1120 if (m->valid == VM_PAGE_BITS_ALL && 1121 (m->flags & PG_FICTITIOUS) == 0) 1122 pmap_enter_quick(pmap, addr, m, entry->protection); 1123 VM_OBJECT_RUNLOCK(lobject); 1124 } 1125 } 1126 1127 /* 1128 * Hold each of the physical pages that are mapped by the specified range of 1129 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid 1130 * and allow the specified types of access, "prot". If all of the implied 1131 * pages are successfully held, then the number of held pages is returned 1132 * together with pointers to those pages in the array "ma". However, if any 1133 * of the pages cannot be held, -1 is returned. 1134 */ 1135 int 1136 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len, 1137 vm_prot_t prot, vm_page_t *ma, int max_count) 1138 { 1139 vm_offset_t end, va; 1140 vm_page_t *mp; 1141 int count; 1142 boolean_t pmap_failed; 1143 1144 if (len == 0) 1145 return (0); 1146 end = round_page(addr + len); 1147 addr = trunc_page(addr); 1148 1149 /* 1150 * Check for illegal addresses. 1151 */ 1152 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map)) 1153 return (-1); 1154 1155 if (atop(end - addr) > max_count) 1156 panic("vm_fault_quick_hold_pages: count > max_count"); 1157 count = atop(end - addr); 1158 1159 /* 1160 * Most likely, the physical pages are resident in the pmap, so it is 1161 * faster to try pmap_extract_and_hold() first. 1162 */ 1163 pmap_failed = FALSE; 1164 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) { 1165 *mp = pmap_extract_and_hold(map->pmap, va, prot); 1166 if (*mp == NULL) 1167 pmap_failed = TRUE; 1168 else if ((prot & VM_PROT_WRITE) != 0 && 1169 (*mp)->dirty != VM_PAGE_BITS_ALL) { 1170 /* 1171 * Explicitly dirty the physical page. Otherwise, the 1172 * caller's changes may go unnoticed because they are 1173 * performed through an unmanaged mapping or by a DMA 1174 * operation. 1175 * 1176 * The object lock is not held here. 1177 * See vm_page_clear_dirty_mask(). 1178 */ 1179 vm_page_dirty(*mp); 1180 } 1181 } 1182 if (pmap_failed) { 1183 /* 1184 * One or more pages could not be held by the pmap. Either no 1185 * page was mapped at the specified virtual address or that 1186 * mapping had insufficient permissions. Attempt to fault in 1187 * and hold these pages. 1188 */ 1189 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) 1190 if (*mp == NULL && vm_fault_hold(map, va, prot, 1191 VM_FAULT_NORMAL, mp) != KERN_SUCCESS) 1192 goto error; 1193 } 1194 return (count); 1195 error: 1196 for (mp = ma; mp < ma + count; mp++) 1197 if (*mp != NULL) { 1198 vm_page_lock(*mp); 1199 vm_page_unhold(*mp); 1200 vm_page_unlock(*mp); 1201 } 1202 return (-1); 1203 } 1204 1205 /* 1206 * Routine: 1207 * vm_fault_copy_entry 1208 * Function: 1209 * Create new shadow object backing dst_entry with private copy of 1210 * all underlying pages. When src_entry is equal to dst_entry, 1211 * function implements COW for wired-down map entry. Otherwise, 1212 * it forks wired entry into dst_map. 1213 * 1214 * In/out conditions: 1215 * The source and destination maps must be locked for write. 1216 * The source map entry must be wired down (or be a sharing map 1217 * entry corresponding to a main map entry that is wired down). 1218 */ 1219 void 1220 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1221 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1222 vm_ooffset_t *fork_charge) 1223 { 1224 vm_object_t backing_object, dst_object, object, src_object; 1225 vm_pindex_t dst_pindex, pindex, src_pindex; 1226 vm_prot_t access, prot; 1227 vm_offset_t vaddr; 1228 vm_page_t dst_m; 1229 vm_page_t src_m; 1230 boolean_t upgrade; 1231 1232 #ifdef lint 1233 src_map++; 1234 #endif /* lint */ 1235 1236 upgrade = src_entry == dst_entry; 1237 access = prot = dst_entry->protection; 1238 1239 src_object = src_entry->object.vm_object; 1240 src_pindex = OFF_TO_IDX(src_entry->offset); 1241 1242 if (upgrade && (dst_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) { 1243 dst_object = src_object; 1244 vm_object_reference(dst_object); 1245 } else { 1246 /* 1247 * Create the top-level object for the destination entry. (Doesn't 1248 * actually shadow anything - we copy the pages directly.) 1249 */ 1250 dst_object = vm_object_allocate(OBJT_DEFAULT, 1251 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1252 #if VM_NRESERVLEVEL > 0 1253 dst_object->flags |= OBJ_COLORED; 1254 dst_object->pg_color = atop(dst_entry->start); 1255 #endif 1256 } 1257 1258 VM_OBJECT_WLOCK(dst_object); 1259 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1260 ("vm_fault_copy_entry: vm_object not NULL")); 1261 if (src_object != dst_object) { 1262 dst_entry->object.vm_object = dst_object; 1263 dst_entry->offset = 0; 1264 dst_object->charge = dst_entry->end - dst_entry->start; 1265 } 1266 if (fork_charge != NULL) { 1267 KASSERT(dst_entry->cred == NULL, 1268 ("vm_fault_copy_entry: leaked swp charge")); 1269 dst_object->cred = curthread->td_ucred; 1270 crhold(dst_object->cred); 1271 *fork_charge += dst_object->charge; 1272 } else if (dst_object->cred == NULL) { 1273 KASSERT(dst_entry->cred != NULL, ("no cred for entry %p", 1274 dst_entry)); 1275 dst_object->cred = dst_entry->cred; 1276 dst_entry->cred = NULL; 1277 } 1278 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 again: 1305 /* 1306 * Find the page in the source object, and copy it in. 1307 * Because the source is wired down, the page will be 1308 * in memory. 1309 */ 1310 if (src_object != dst_object) 1311 VM_OBJECT_RLOCK(src_object); 1312 object = src_object; 1313 pindex = src_pindex + dst_pindex; 1314 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1315 (backing_object = object->backing_object) != NULL) { 1316 /* 1317 * Unless the source mapping is read-only or 1318 * it is presently being upgraded from 1319 * read-only, the first object in the shadow 1320 * chain should provide all of the pages. In 1321 * other words, this loop body should never be 1322 * executed when the source mapping is already 1323 * read/write. 1324 */ 1325 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 || 1326 upgrade, 1327 ("vm_fault_copy_entry: main object missing page")); 1328 1329 VM_OBJECT_RLOCK(backing_object); 1330 pindex += OFF_TO_IDX(object->backing_object_offset); 1331 if (object != dst_object) 1332 VM_OBJECT_RUNLOCK(object); 1333 object = backing_object; 1334 } 1335 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing")); 1336 1337 if (object != dst_object) { 1338 /* 1339 * Allocate a page in the destination object. 1340 */ 1341 dst_m = vm_page_alloc(dst_object, (src_object == 1342 dst_object ? src_pindex : 0) + dst_pindex, 1343 VM_ALLOC_NORMAL); 1344 if (dst_m == NULL) { 1345 VM_OBJECT_WUNLOCK(dst_object); 1346 VM_OBJECT_RUNLOCK(object); 1347 VM_WAIT; 1348 VM_OBJECT_WLOCK(dst_object); 1349 goto again; 1350 } 1351 pmap_copy_page(src_m, dst_m); 1352 VM_OBJECT_RUNLOCK(object); 1353 dst_m->valid = VM_PAGE_BITS_ALL; 1354 dst_m->dirty = VM_PAGE_BITS_ALL; 1355 } else { 1356 dst_m = src_m; 1357 if (vm_page_sleep_if_busy(dst_m, "fltupg")) 1358 goto again; 1359 vm_page_xbusy(dst_m); 1360 KASSERT(dst_m->valid == VM_PAGE_BITS_ALL, 1361 ("invalid dst page %p", dst_m)); 1362 } 1363 VM_OBJECT_WUNLOCK(dst_object); 1364 1365 /* 1366 * Enter it in the pmap. If a wired, copy-on-write 1367 * mapping is being replaced by a write-enabled 1368 * mapping, then wire that new mapping. 1369 */ 1370 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, 1371 access | (upgrade ? PMAP_ENTER_WIRED : 0), 0); 1372 1373 /* 1374 * Mark it no longer busy, and put it on the active list. 1375 */ 1376 VM_OBJECT_WLOCK(dst_object); 1377 1378 if (upgrade) { 1379 if (src_m != dst_m) { 1380 vm_page_lock(src_m); 1381 vm_page_unwire(src_m, PQ_INACTIVE); 1382 vm_page_unlock(src_m); 1383 vm_page_lock(dst_m); 1384 vm_page_wire(dst_m); 1385 vm_page_unlock(dst_m); 1386 } else { 1387 KASSERT(dst_m->wire_count > 0, 1388 ("dst_m %p is not wired", dst_m)); 1389 } 1390 } else { 1391 vm_page_lock(dst_m); 1392 vm_page_activate(dst_m); 1393 vm_page_unlock(dst_m); 1394 } 1395 vm_page_xunbusy(dst_m); 1396 } 1397 VM_OBJECT_WUNLOCK(dst_object); 1398 if (upgrade) { 1399 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1400 vm_object_deallocate(src_object); 1401 } 1402 } 1403 1404 1405 /* 1406 * This routine checks around the requested page for other pages that 1407 * might be able to be faulted in. This routine brackets the viable 1408 * pages for the pages to be paged in. 1409 * 1410 * Inputs: 1411 * m, rbehind, rahead 1412 * 1413 * Outputs: 1414 * marray (array of vm_page_t), reqpage (index of requested page) 1415 * 1416 * Return value: 1417 * number of pages in marray 1418 */ 1419 static int 1420 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1421 vm_page_t m; 1422 int rbehind; 1423 int rahead; 1424 vm_page_t *marray; 1425 int *reqpage; 1426 { 1427 int i,j; 1428 vm_object_t object; 1429 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1430 vm_page_t rtm; 1431 int cbehind, cahead; 1432 1433 VM_OBJECT_ASSERT_WLOCKED(m->object); 1434 1435 object = m->object; 1436 pindex = m->pindex; 1437 cbehind = cahead = 0; 1438 1439 /* 1440 * if the requested page is not available, then give up now 1441 */ 1442 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1443 return 0; 1444 } 1445 1446 if ((cbehind == 0) && (cahead == 0)) { 1447 *reqpage = 0; 1448 marray[0] = m; 1449 return 1; 1450 } 1451 1452 if (rahead > cahead) { 1453 rahead = cahead; 1454 } 1455 1456 if (rbehind > cbehind) { 1457 rbehind = cbehind; 1458 } 1459 1460 /* 1461 * scan backward for the read behind pages -- in memory 1462 */ 1463 if (pindex > 0) { 1464 if (rbehind > pindex) { 1465 rbehind = pindex; 1466 startpindex = 0; 1467 } else { 1468 startpindex = pindex - rbehind; 1469 } 1470 1471 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1472 rtm->pindex >= startpindex) 1473 startpindex = rtm->pindex + 1; 1474 1475 /* tpindex is unsigned; beware of numeric underflow. */ 1476 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1477 tpindex < pindex; i++, tpindex--) { 1478 1479 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1480 VM_ALLOC_IFNOTCACHED); 1481 if (rtm == NULL) { 1482 /* 1483 * Shift the allocated pages to the 1484 * beginning of the array. 1485 */ 1486 for (j = 0; j < i; j++) { 1487 marray[j] = marray[j + tpindex + 1 - 1488 startpindex]; 1489 } 1490 break; 1491 } 1492 1493 marray[tpindex - startpindex] = rtm; 1494 } 1495 } else { 1496 startpindex = 0; 1497 i = 0; 1498 } 1499 1500 marray[i] = m; 1501 /* page offset of the required page */ 1502 *reqpage = i; 1503 1504 tpindex = pindex + 1; 1505 i++; 1506 1507 /* 1508 * scan forward for the read ahead pages 1509 */ 1510 endpindex = tpindex + rahead; 1511 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1512 endpindex = rtm->pindex; 1513 if (endpindex > object->size) 1514 endpindex = object->size; 1515 1516 for (; tpindex < endpindex; i++, tpindex++) { 1517 1518 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1519 VM_ALLOC_IFNOTCACHED); 1520 if (rtm == NULL) { 1521 break; 1522 } 1523 1524 marray[i] = rtm; 1525 } 1526 1527 /* return number of pages */ 1528 return i; 1529 } 1530 1531 /* 1532 * Block entry into the machine-independent layer's page fault handler by 1533 * the calling thread. Subsequent calls to vm_fault() by that thread will 1534 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of 1535 * spurious page faults. 1536 */ 1537 int 1538 vm_fault_disable_pagefaults(void) 1539 { 1540 1541 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR)); 1542 } 1543 1544 void 1545 vm_fault_enable_pagefaults(int save) 1546 { 1547 1548 curthread_pflags_restore(save); 1549 } 1550