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sys/vm/vm_fault.c
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1 /*- 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * 9 * 10 * This code is derived from software contributed to Berkeley by 11 * The Mach Operating System project at Carnegie-Mellon University. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94 42 * 43 * 44 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 45 * All rights reserved. 46 * 47 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 48 * 49 * Permission to use, copy, modify and distribute this software and 50 * its documentation is hereby granted, provided that both the copyright 51 * notice and this permission notice appear in all copies of the 52 * software, derivative works or modified versions, and any portions 53 * thereof, and that both notices appear in supporting documentation. 54 * 55 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 56 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 57 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 58 * 59 * Carnegie Mellon requests users of this software to return to 60 * 61 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 62 * School of Computer Science 63 * Carnegie Mellon University 64 * Pittsburgh PA 15213-3890 65 * 66 * any improvements or extensions that they make and grant Carnegie the 67 * rights to redistribute these changes. 68 */ 69 70 /* 71 * Page fault handling module. 72 */ 73 74 #include <sys/cdefs.h> 75 __FBSDID("$FreeBSD$"); 76 77 #include "opt_ktrace.h" 78 #include "opt_vm.h" 79 80 #include <sys/param.h> 81 #include <sys/systm.h> 82 #include <sys/kernel.h> 83 #include <sys/lock.h> 84 #include <sys/mutex.h> 85 #include <sys/proc.h> 86 #include <sys/resourcevar.h> 87 #include <sys/sysctl.h> 88 #include <sys/vmmeter.h> 89 #include <sys/vnode.h> 90 #ifdef KTRACE 91 #include <sys/ktrace.h> 92 #endif 93 94 #include <vm/vm.h> 95 #include <vm/vm_param.h> 96 #include <vm/pmap.h> 97 #include <vm/vm_map.h> 98 #include <vm/vm_object.h> 99 #include <vm/vm_page.h> 100 #include <vm/vm_pageout.h> 101 #include <vm/vm_kern.h> 102 #include <vm/vm_pager.h> 103 #include <vm/vm_extern.h> 104 105 #include <sys/mount.h> /* XXX Temporary for VFS_LOCK_GIANT() */ 106 107 #define PFBAK 4 108 #define PFFOR 4 109 #define PAGEORDER_SIZE (PFBAK+PFFOR) 110 111 static int prefault_pageorder[] = { 112 -1 * PAGE_SIZE, 1 * PAGE_SIZE, 113 -2 * PAGE_SIZE, 2 * PAGE_SIZE, 114 -3 * PAGE_SIZE, 3 * PAGE_SIZE, 115 -4 * PAGE_SIZE, 4 * PAGE_SIZE 116 }; 117 118 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); 119 static void vm_fault_prefault(pmap_t, vm_offset_t, vm_map_entry_t); 120 121 #define VM_FAULT_READ_BEHIND 8 122 #define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX) 123 #define VM_FAULT_NINCR (VM_FAULT_READ_MAX / VM_FAULT_READ_BEHIND) 124 #define VM_FAULT_SUM (VM_FAULT_NINCR * (VM_FAULT_NINCR + 1) / 2) 125 #define VM_FAULT_CACHE_BEHIND (VM_FAULT_READ_BEHIND * VM_FAULT_SUM) 126 127 struct faultstate { 128 vm_page_t m; 129 vm_object_t object; 130 vm_pindex_t pindex; 131 vm_page_t first_m; 132 vm_object_t first_object; 133 vm_pindex_t first_pindex; 134 vm_map_t map; 135 vm_map_entry_t entry; 136 int lookup_still_valid; 137 struct vnode *vp; 138 int vfslocked; 139 }; 140 141 static void vm_fault_cache_behind(const struct faultstate *fs, int distance); 142 143 static inline void 144 release_page(struct faultstate *fs) 145 { 146 147 vm_page_wakeup(fs->m); 148 vm_page_lock(fs->m); 149 vm_page_deactivate(fs->m); 150 vm_page_unlock(fs->m); 151 fs->m = NULL; 152 } 153 154 static inline void 155 unlock_map(struct faultstate *fs) 156 { 157 158 if (fs->lookup_still_valid) { 159 vm_map_lookup_done(fs->map, fs->entry); 160 fs->lookup_still_valid = FALSE; 161 } 162 } 163 164 static void 165 unlock_and_deallocate(struct faultstate *fs) 166 { 167 168 vm_object_pip_wakeup(fs->object); 169 VM_OBJECT_UNLOCK(fs->object); 170 if (fs->object != fs->first_object) { 171 VM_OBJECT_LOCK(fs->first_object); 172 vm_page_lock(fs->first_m); 173 vm_page_free(fs->first_m); 174 vm_page_unlock(fs->first_m); 175 vm_object_pip_wakeup(fs->first_object); 176 VM_OBJECT_UNLOCK(fs->first_object); 177 fs->first_m = NULL; 178 } 179 vm_object_deallocate(fs->first_object); 180 unlock_map(fs); 181 if (fs->vp != NULL) { 182 vput(fs->vp); 183 fs->vp = NULL; 184 } 185 VFS_UNLOCK_GIANT(fs->vfslocked); 186 fs->vfslocked = 0; 187 } 188 189 /* 190 * TRYPAGER - used by vm_fault to calculate whether the pager for the 191 * current object *might* contain the page. 192 * 193 * default objects are zero-fill, there is no real pager. 194 */ 195 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 196 ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 || wired)) 197 198 /* 199 * vm_fault: 200 * 201 * Handle a page fault occurring at the given address, 202 * requiring the given permissions, in the map specified. 203 * If successful, the page is inserted into the 204 * associated physical map. 205 * 206 * NOTE: the given address should be truncated to the 207 * proper page address. 208 * 209 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 210 * a standard error specifying why the fault is fatal is returned. 211 * 212 * The map in question must be referenced, and remains so. 213 * Caller may hold no locks. 214 */ 215 int 216 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 217 int fault_flags) 218 { 219 struct thread *td; 220 int result; 221 222 td = curthread; 223 if ((td->td_pflags & TDP_NOFAULTING) != 0) 224 return (KERN_PROTECTION_FAILURE); 225 #ifdef KTRACE 226 if (map != kernel_map && KTRPOINT(td, KTR_FAULT)) 227 ktrfault(vaddr, fault_type); 228 #endif 229 result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags, 230 NULL); 231 #ifdef KTRACE 232 if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND)) 233 ktrfaultend(result); 234 #endif 235 return (result); 236 } 237 238 int 239 vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 240 int fault_flags, vm_page_t *m_hold) 241 { 242 vm_prot_t prot; 243 long ahead, behind; 244 int alloc_req, era, faultcount, nera, reqpage, result; 245 boolean_t growstack, is_first_object_locked, wired; 246 int map_generation; 247 vm_object_t next_object; 248 vm_page_t marray[VM_FAULT_READ_MAX]; 249 int hardfault; 250 struct faultstate fs; 251 struct vnode *vp; 252 int locked, error; 253 254 hardfault = 0; 255 growstack = TRUE; 256 PCPU_INC(cnt.v_vm_faults); 257 fs.vp = NULL; 258 fs.vfslocked = 0; 259 faultcount = reqpage = 0; 260 261 RetryFault:; 262 263 /* 264 * Find the backing store object and offset into it to begin the 265 * search. 266 */ 267 fs.map = map; 268 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 269 &fs.first_object, &fs.first_pindex, &prot, &wired); 270 if (result != KERN_SUCCESS) { 271 if (growstack && result == KERN_INVALID_ADDRESS && 272 map != kernel_map) { 273 result = vm_map_growstack(curproc, vaddr); 274 if (result != KERN_SUCCESS) 275 return (KERN_FAILURE); 276 growstack = FALSE; 277 goto RetryFault; 278 } 279 return (result); 280 } 281 282 map_generation = fs.map->timestamp; 283 284 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 285 if ((curthread->td_pflags & TDP_DEVMEMIO) != 0) { 286 vm_map_unlock_read(fs.map); 287 return (KERN_FAILURE); 288 } 289 panic("vm_fault: fault on nofault entry, addr: %lx", 290 (u_long)vaddr); 291 } 292 293 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION && 294 fs.entry->wiring_thread != curthread) { 295 vm_map_unlock_read(fs.map); 296 vm_map_lock(fs.map); 297 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) && 298 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) { 299 if (fs.vp != NULL) { 300 vput(fs.vp); 301 fs.vp = NULL; 302 } 303 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP; 304 vm_map_unlock_and_wait(fs.map, 0); 305 } else 306 vm_map_unlock(fs.map); 307 goto RetryFault; 308 } 309 310 /* 311 * Make a reference to this object to prevent its disposal while we 312 * are messing with it. Once we have the reference, the map is free 313 * to be diddled. Since objects reference their shadows (and copies), 314 * they will stay around as well. 315 * 316 * Bump the paging-in-progress count to prevent size changes (e.g. 317 * truncation operations) during I/O. This must be done after 318 * obtaining the vnode lock in order to avoid possible deadlocks. 319 */ 320 VM_OBJECT_LOCK(fs.first_object); 321 vm_object_reference_locked(fs.first_object); 322 vm_object_pip_add(fs.first_object, 1); 323 324 fs.lookup_still_valid = TRUE; 325 326 if (wired) 327 fault_type = prot | (fault_type & VM_PROT_COPY); 328 329 fs.first_m = NULL; 330 331 /* 332 * Search for the page at object/offset. 333 */ 334 fs.object = fs.first_object; 335 fs.pindex = fs.first_pindex; 336 while (TRUE) { 337 /* 338 * If the object is dead, we stop here 339 */ 340 if (fs.object->flags & OBJ_DEAD) { 341 unlock_and_deallocate(&fs); 342 return (KERN_PROTECTION_FAILURE); 343 } 344 345 /* 346 * See if page is resident 347 */ 348 fs.m = vm_page_lookup(fs.object, fs.pindex); 349 if (fs.m != NULL) { 350 /* 351 * check for page-based copy on write. 352 * We check fs.object == fs.first_object so 353 * as to ensure the legacy COW mechanism is 354 * used when the page in question is part of 355 * a shadow object. Otherwise, vm_page_cowfault() 356 * removes the page from the backing object, 357 * which is not what we want. 358 */ 359 vm_page_lock(fs.m); 360 if ((fs.m->cow) && 361 (fault_type & VM_PROT_WRITE) && 362 (fs.object == fs.first_object)) { 363 vm_page_cowfault(fs.m); 364 unlock_and_deallocate(&fs); 365 goto RetryFault; 366 } 367 368 /* 369 * Wait/Retry if the page is busy. We have to do this 370 * if the page is busy via either VPO_BUSY or 371 * vm_page_t->busy because the vm_pager may be using 372 * vm_page_t->busy for pageouts ( and even pageins if 373 * it is the vnode pager ), and we could end up trying 374 * to pagein and pageout the same page simultaneously. 375 * 376 * We can theoretically allow the busy case on a read 377 * fault if the page is marked valid, but since such 378 * pages are typically already pmap'd, putting that 379 * special case in might be more effort then it is 380 * worth. We cannot under any circumstances mess 381 * around with a vm_page_t->busy page except, perhaps, 382 * to pmap it. 383 */ 384 if ((fs.m->oflags & VPO_BUSY) || fs.m->busy) { 385 /* 386 * Reference the page before unlocking and 387 * sleeping so that the page daemon is less 388 * likely to reclaim it. 389 */ 390 vm_page_aflag_set(fs.m, PGA_REFERENCED); 391 vm_page_unlock(fs.m); 392 if (fs.object != fs.first_object) { 393 if (!VM_OBJECT_TRYLOCK( 394 fs.first_object)) { 395 VM_OBJECT_UNLOCK(fs.object); 396 VM_OBJECT_LOCK(fs.first_object); 397 VM_OBJECT_LOCK(fs.object); 398 } 399 vm_page_lock(fs.first_m); 400 vm_page_free(fs.first_m); 401 vm_page_unlock(fs.first_m); 402 vm_object_pip_wakeup(fs.first_object); 403 VM_OBJECT_UNLOCK(fs.first_object); 404 fs.first_m = NULL; 405 } 406 unlock_map(&fs); 407 if (fs.m == vm_page_lookup(fs.object, 408 fs.pindex)) { 409 vm_page_sleep_if_busy(fs.m, TRUE, 410 "vmpfw"); 411 } 412 vm_object_pip_wakeup(fs.object); 413 VM_OBJECT_UNLOCK(fs.object); 414 PCPU_INC(cnt.v_intrans); 415 vm_object_deallocate(fs.first_object); 416 goto RetryFault; 417 } 418 vm_pageq_remove(fs.m); 419 vm_page_unlock(fs.m); 420 421 /* 422 * Mark page busy for other processes, and the 423 * pagedaemon. If it still isn't completely valid 424 * (readable), jump to readrest, else break-out ( we 425 * found the page ). 426 */ 427 vm_page_busy(fs.m); 428 if (fs.m->valid != VM_PAGE_BITS_ALL) 429 goto readrest; 430 break; 431 } 432 433 /* 434 * Page is not resident, If this is the search termination 435 * or the pager might contain the page, allocate a new page. 436 */ 437 if (TRYPAGER || fs.object == fs.first_object) { 438 if (fs.pindex >= fs.object->size) { 439 unlock_and_deallocate(&fs); 440 return (KERN_PROTECTION_FAILURE); 441 } 442 443 /* 444 * Allocate a new page for this object/offset pair. 445 * 446 * Unlocked read of the p_flag is harmless. At 447 * worst, the P_KILLED might be not observed 448 * there, and allocation can fail, causing 449 * restart and new reading of the p_flag. 450 */ 451 fs.m = NULL; 452 if (!vm_page_count_severe() || P_KILLED(curproc)) { 453 #if VM_NRESERVLEVEL > 0 454 if ((fs.object->flags & OBJ_COLORED) == 0) { 455 fs.object->flags |= OBJ_COLORED; 456 fs.object->pg_color = atop(vaddr) - 457 fs.pindex; 458 } 459 #endif 460 alloc_req = P_KILLED(curproc) ? 461 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 462 if (fs.object->type != OBJT_VNODE && 463 fs.object->backing_object == NULL) 464 alloc_req |= VM_ALLOC_ZERO; 465 fs.m = vm_page_alloc(fs.object, fs.pindex, 466 alloc_req); 467 } 468 if (fs.m == NULL) { 469 unlock_and_deallocate(&fs); 470 VM_WAITPFAULT; 471 goto RetryFault; 472 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 473 break; 474 } 475 476 readrest: 477 /* 478 * We have found a valid page or we have allocated a new page. 479 * The page thus may not be valid or may not be entirely 480 * valid. 481 * 482 * Attempt to fault-in the page if there is a chance that the 483 * pager has it, and potentially fault in additional pages 484 * at the same time. 485 */ 486 if (TRYPAGER) { 487 int rv; 488 u_char behavior = vm_map_entry_behavior(fs.entry); 489 490 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 491 P_KILLED(curproc)) { 492 behind = 0; 493 ahead = 0; 494 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) { 495 behind = 0; 496 ahead = atop(fs.entry->end - vaddr) - 1; 497 if (ahead > VM_FAULT_READ_AHEAD_MAX) 498 ahead = VM_FAULT_READ_AHEAD_MAX; 499 if (fs.pindex == fs.entry->next_read) 500 vm_fault_cache_behind(&fs, 501 VM_FAULT_READ_MAX); 502 } else { 503 /* 504 * If this is a sequential page fault, then 505 * arithmetically increase the number of pages 506 * in the read-ahead window. Otherwise, reset 507 * the read-ahead window to its smallest size. 508 */ 509 behind = atop(vaddr - fs.entry->start); 510 if (behind > VM_FAULT_READ_BEHIND) 511 behind = VM_FAULT_READ_BEHIND; 512 ahead = atop(fs.entry->end - vaddr) - 1; 513 era = fs.entry->read_ahead; 514 if (fs.pindex == fs.entry->next_read) { 515 nera = era + behind; 516 if (nera > VM_FAULT_READ_AHEAD_MAX) 517 nera = VM_FAULT_READ_AHEAD_MAX; 518 behind = 0; 519 if (ahead > nera) 520 ahead = nera; 521 if (era == VM_FAULT_READ_AHEAD_MAX) 522 vm_fault_cache_behind(&fs, 523 VM_FAULT_CACHE_BEHIND); 524 } else if (ahead > VM_FAULT_READ_AHEAD_MIN) 525 ahead = VM_FAULT_READ_AHEAD_MIN; 526 if (era != ahead) 527 fs.entry->read_ahead = ahead; 528 } 529 530 /* 531 * Call the pager to retrieve the data, if any, after 532 * releasing the lock on the map. We hold a ref on 533 * fs.object and the pages are VPO_BUSY'd. 534 */ 535 unlock_map(&fs); 536 537 vnode_lock: 538 if (fs.object->type == OBJT_VNODE) { 539 vp = fs.object->handle; 540 if (vp == fs.vp) 541 goto vnode_locked; 542 else if (fs.vp != NULL) { 543 vput(fs.vp); 544 fs.vp = NULL; 545 } 546 locked = VOP_ISLOCKED(vp); 547 548 if (VFS_NEEDSGIANT(vp->v_mount) && !fs.vfslocked) { 549 fs.vfslocked = 1; 550 if (!mtx_trylock(&Giant)) { 551 VM_OBJECT_UNLOCK(fs.object); 552 mtx_lock(&Giant); 553 VM_OBJECT_LOCK(fs.object); 554 goto vnode_lock; 555 } 556 } 557 if (locked != LK_EXCLUSIVE) 558 locked = LK_SHARED; 559 /* Do not sleep for vnode lock while fs.m is busy */ 560 error = vget(vp, locked | LK_CANRECURSE | 561 LK_NOWAIT, curthread); 562 if (error != 0) { 563 int vfslocked; 564 565 vfslocked = fs.vfslocked; 566 fs.vfslocked = 0; /* Keep Giant */ 567 vhold(vp); 568 release_page(&fs); 569 unlock_and_deallocate(&fs); 570 error = vget(vp, locked | LK_RETRY | 571 LK_CANRECURSE, curthread); 572 vdrop(vp); 573 fs.vp = vp; 574 fs.vfslocked = vfslocked; 575 KASSERT(error == 0, 576 ("vm_fault: vget failed")); 577 goto RetryFault; 578 } 579 fs.vp = vp; 580 } 581 vnode_locked: 582 KASSERT(fs.vp == NULL || !fs.map->system_map, 583 ("vm_fault: vnode-backed object mapped by system map")); 584 585 /* 586 * now we find out if any other pages should be paged 587 * in at this time this routine checks to see if the 588 * pages surrounding this fault reside in the same 589 * object as the page for this fault. If they do, 590 * then they are faulted in also into the object. The 591 * array "marray" returned contains an array of 592 * vm_page_t structs where one of them is the 593 * vm_page_t passed to the routine. The reqpage 594 * return value is the index into the marray for the 595 * vm_page_t passed to the routine. 596 * 597 * fs.m plus the additional pages are VPO_BUSY'd. 598 */ 599 faultcount = vm_fault_additional_pages( 600 fs.m, behind, ahead, marray, &reqpage); 601 602 rv = faultcount ? 603 vm_pager_get_pages(fs.object, marray, faultcount, 604 reqpage) : VM_PAGER_FAIL; 605 606 if (rv == VM_PAGER_OK) { 607 /* 608 * Found the page. Leave it busy while we play 609 * with it. 610 */ 611 612 /* 613 * Relookup in case pager changed page. Pager 614 * is responsible for disposition of old page 615 * if moved. 616 */ 617 fs.m = vm_page_lookup(fs.object, fs.pindex); 618 if (!fs.m) { 619 unlock_and_deallocate(&fs); 620 goto RetryFault; 621 } 622 623 hardfault++; 624 break; /* break to PAGE HAS BEEN FOUND */ 625 } 626 /* 627 * Remove the bogus page (which does not exist at this 628 * object/offset); before doing so, we must get back 629 * our object lock to preserve our invariant. 630 * 631 * Also wake up any other process that may want to bring 632 * in this page. 633 * 634 * If this is the top-level object, we must leave the 635 * busy page to prevent another process from rushing 636 * past us, and inserting the page in that object at 637 * the same time that we are. 638 */ 639 if (rv == VM_PAGER_ERROR) 640 printf("vm_fault: pager read error, pid %d (%s)\n", 641 curproc->p_pid, curproc->p_comm); 642 /* 643 * Data outside the range of the pager or an I/O error 644 */ 645 /* 646 * XXX - the check for kernel_map is a kludge to work 647 * around having the machine panic on a kernel space 648 * fault w/ I/O error. 649 */ 650 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 651 (rv == VM_PAGER_BAD)) { 652 vm_page_lock(fs.m); 653 vm_page_free(fs.m); 654 vm_page_unlock(fs.m); 655 fs.m = NULL; 656 unlock_and_deallocate(&fs); 657 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 658 } 659 if (fs.object != fs.first_object) { 660 vm_page_lock(fs.m); 661 vm_page_free(fs.m); 662 vm_page_unlock(fs.m); 663 fs.m = NULL; 664 /* 665 * XXX - we cannot just fall out at this 666 * point, m has been freed and is invalid! 667 */ 668 } 669 } 670 671 /* 672 * We get here if the object has default pager (or unwiring) 673 * or the pager doesn't have the page. 674 */ 675 if (fs.object == fs.first_object) 676 fs.first_m = fs.m; 677 678 /* 679 * Move on to the next object. Lock the next object before 680 * unlocking the current one. 681 */ 682 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 683 next_object = fs.object->backing_object; 684 if (next_object == NULL) { 685 /* 686 * If there's no object left, fill the page in the top 687 * object with zeros. 688 */ 689 if (fs.object != fs.first_object) { 690 vm_object_pip_wakeup(fs.object); 691 VM_OBJECT_UNLOCK(fs.object); 692 693 fs.object = fs.first_object; 694 fs.pindex = fs.first_pindex; 695 fs.m = fs.first_m; 696 VM_OBJECT_LOCK(fs.object); 697 } 698 fs.first_m = NULL; 699 700 /* 701 * Zero the page if necessary and mark it valid. 702 */ 703 if ((fs.m->flags & PG_ZERO) == 0) { 704 pmap_zero_page(fs.m); 705 } else { 706 PCPU_INC(cnt.v_ozfod); 707 } 708 PCPU_INC(cnt.v_zfod); 709 fs.m->valid = VM_PAGE_BITS_ALL; 710 break; /* break to PAGE HAS BEEN FOUND */ 711 } else { 712 KASSERT(fs.object != next_object, 713 ("object loop %p", next_object)); 714 VM_OBJECT_LOCK(next_object); 715 vm_object_pip_add(next_object, 1); 716 if (fs.object != fs.first_object) 717 vm_object_pip_wakeup(fs.object); 718 VM_OBJECT_UNLOCK(fs.object); 719 fs.object = next_object; 720 } 721 } 722 723 KASSERT((fs.m->oflags & VPO_BUSY) != 0, 724 ("vm_fault: not busy after main loop")); 725 726 /* 727 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 728 * is held.] 729 */ 730 731 /* 732 * If the page is being written, but isn't already owned by the 733 * top-level object, we have to copy it into a new page owned by the 734 * top-level object. 735 */ 736 if (fs.object != fs.first_object) { 737 /* 738 * We only really need to copy if we want to write it. 739 */ 740 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 741 /* 742 * This allows pages to be virtually copied from a 743 * backing_object into the first_object, where the 744 * backing object has no other refs to it, and cannot 745 * gain any more refs. Instead of a bcopy, we just 746 * move the page from the backing object to the 747 * first object. Note that we must mark the page 748 * dirty in the first object so that it will go out 749 * to swap when needed. 750 */ 751 is_first_object_locked = FALSE; 752 if ( 753 /* 754 * Only one shadow object 755 */ 756 (fs.object->shadow_count == 1) && 757 /* 758 * No COW refs, except us 759 */ 760 (fs.object->ref_count == 1) && 761 /* 762 * No one else can look this object up 763 */ 764 (fs.object->handle == NULL) && 765 /* 766 * No other ways to look the object up 767 */ 768 ((fs.object->type == OBJT_DEFAULT) || 769 (fs.object->type == OBJT_SWAP)) && 770 (is_first_object_locked = VM_OBJECT_TRYLOCK(fs.first_object)) && 771 /* 772 * We don't chase down the shadow chain 773 */ 774 fs.object == fs.first_object->backing_object) { 775 /* 776 * get rid of the unnecessary page 777 */ 778 vm_page_lock(fs.first_m); 779 vm_page_free(fs.first_m); 780 vm_page_unlock(fs.first_m); 781 /* 782 * grab the page and put it into the 783 * process'es object. The page is 784 * automatically made dirty. 785 */ 786 vm_page_lock(fs.m); 787 vm_page_rename(fs.m, fs.first_object, fs.first_pindex); 788 vm_page_unlock(fs.m); 789 vm_page_busy(fs.m); 790 fs.first_m = fs.m; 791 fs.m = NULL; 792 PCPU_INC(cnt.v_cow_optim); 793 } else { 794 /* 795 * Oh, well, lets copy it. 796 */ 797 pmap_copy_page(fs.m, fs.first_m); 798 fs.first_m->valid = VM_PAGE_BITS_ALL; 799 if (wired && (fault_flags & 800 VM_FAULT_CHANGE_WIRING) == 0) { 801 vm_page_lock(fs.first_m); 802 vm_page_wire(fs.first_m); 803 vm_page_unlock(fs.first_m); 804 805 vm_page_lock(fs.m); 806 vm_page_unwire(fs.m, FALSE); 807 vm_page_unlock(fs.m); 808 } 809 /* 810 * We no longer need the old page or object. 811 */ 812 release_page(&fs); 813 } 814 /* 815 * fs.object != fs.first_object due to above 816 * conditional 817 */ 818 vm_object_pip_wakeup(fs.object); 819 VM_OBJECT_UNLOCK(fs.object); 820 /* 821 * Only use the new page below... 822 */ 823 fs.object = fs.first_object; 824 fs.pindex = fs.first_pindex; 825 fs.m = fs.first_m; 826 if (!is_first_object_locked) 827 VM_OBJECT_LOCK(fs.object); 828 PCPU_INC(cnt.v_cow_faults); 829 curthread->td_cow++; 830 } else { 831 prot &= ~VM_PROT_WRITE; 832 } 833 } 834 835 /* 836 * We must verify that the maps have not changed since our last 837 * lookup. 838 */ 839 if (!fs.lookup_still_valid) { 840 vm_object_t retry_object; 841 vm_pindex_t retry_pindex; 842 vm_prot_t retry_prot; 843 844 if (!vm_map_trylock_read(fs.map)) { 845 release_page(&fs); 846 unlock_and_deallocate(&fs); 847 goto RetryFault; 848 } 849 fs.lookup_still_valid = TRUE; 850 if (fs.map->timestamp != map_generation) { 851 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 852 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 853 854 /* 855 * If we don't need the page any longer, put it on the inactive 856 * list (the easiest thing to do here). If no one needs it, 857 * pageout will grab it eventually. 858 */ 859 if (result != KERN_SUCCESS) { 860 release_page(&fs); 861 unlock_and_deallocate(&fs); 862 863 /* 864 * If retry of map lookup would have blocked then 865 * retry fault from start. 866 */ 867 if (result == KERN_FAILURE) 868 goto RetryFault; 869 return (result); 870 } 871 if ((retry_object != fs.first_object) || 872 (retry_pindex != fs.first_pindex)) { 873 release_page(&fs); 874 unlock_and_deallocate(&fs); 875 goto RetryFault; 876 } 877 878 /* 879 * Check whether the protection has changed or the object has 880 * been copied while we left the map unlocked. Changing from 881 * read to write permission is OK - we leave the page 882 * write-protected, and catch the write fault. Changing from 883 * write to read permission means that we can't mark the page 884 * write-enabled after all. 885 */ 886 prot &= retry_prot; 887 } 888 } 889 /* 890 * If the page was filled by a pager, update the map entry's 891 * last read offset. Since the pager does not return the 892 * actual set of pages that it read, this update is based on 893 * the requested set. Typically, the requested and actual 894 * sets are the same. 895 * 896 * XXX The following assignment modifies the map 897 * without holding a write lock on it. 898 */ 899 if (hardfault) 900 fs.entry->next_read = fs.pindex + faultcount - reqpage; 901 902 if ((prot & VM_PROT_WRITE) != 0 || 903 (fault_flags & VM_FAULT_DIRTY) != 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 /* 938 * Page had better still be busy 939 */ 940 KASSERT(fs.m->oflags & VPO_BUSY, 941 ("vm_fault: page %p not busy!", fs.m)); 942 /* 943 * Page must be completely valid or it is not fit to 944 * map into user space. vm_pager_get_pages() ensures this. 945 */ 946 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 947 ("vm_fault: page %p partially invalid", fs.m)); 948 VM_OBJECT_UNLOCK(fs.object); 949 950 /* 951 * Put this page into the physical map. We had to do the unlock above 952 * because pmap_enter() may sleep. We don't put the page 953 * back on the active queue until later so that the pageout daemon 954 * won't find it (yet). 955 */ 956 pmap_enter(fs.map->pmap, vaddr, fault_type, fs.m, prot, wired); 957 if ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && wired == 0) 958 vm_fault_prefault(fs.map->pmap, vaddr, fs.entry); 959 VM_OBJECT_LOCK(fs.object); 960 vm_page_lock(fs.m); 961 962 /* 963 * If the page is not wired down, then put it where the pageout daemon 964 * can find it. 965 */ 966 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 967 if (wired) 968 vm_page_wire(fs.m); 969 else 970 vm_page_unwire(fs.m, 1); 971 } else 972 vm_page_activate(fs.m); 973 if (m_hold != NULL) { 974 *m_hold = fs.m; 975 vm_page_hold(fs.m); 976 } 977 vm_page_unlock(fs.m); 978 vm_page_wakeup(fs.m); 979 980 /* 981 * Unlock everything, and return 982 */ 983 unlock_and_deallocate(&fs); 984 if (hardfault) 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_LOCK_ASSERT(object, MA_OWNED); 1005 first_object = fs->first_object; 1006 if (first_object != object) { 1007 if (!VM_OBJECT_TRYLOCK(first_object)) { 1008 VM_OBJECT_UNLOCK(object); 1009 VM_OBJECT_LOCK(first_object); 1010 VM_OBJECT_LOCK(object); 1011 } 1012 } 1013 if (first_object->type != OBJT_DEVICE && 1014 first_object->type != OBJT_PHYS && first_object->type != OBJT_SG) { 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 KASSERT((m->oflags & VPO_BUSY) != 0, 1023 ("vm_fault_cache_behind: page %p is not busy", m)); 1024 m_prev = vm_page_prev(m); 1025 while ((m = m_prev) != NULL && m->pindex >= pindex && 1026 m->valid == VM_PAGE_BITS_ALL) { 1027 m_prev = vm_page_prev(m); 1028 if (m->busy != 0 || (m->oflags & VPO_BUSY) != 0) 1029 continue; 1030 vm_page_lock(m); 1031 if (m->hold_count == 0 && m->wire_count == 0) { 1032 pmap_remove_all(m); 1033 vm_page_aflag_clear(m, PGA_REFERENCED); 1034 if (m->dirty != 0) 1035 vm_page_deactivate(m); 1036 else 1037 vm_page_cache(m); 1038 } 1039 vm_page_unlock(m); 1040 } 1041 } 1042 if (first_object != object) 1043 VM_OBJECT_UNLOCK(first_object); 1044 } 1045 1046 /* 1047 * vm_fault_prefault provides a quick way of clustering 1048 * pagefaults into a processes address space. It is a "cousin" 1049 * of vm_map_pmap_enter, except it runs at page fault time instead 1050 * of mmap time. 1051 */ 1052 static void 1053 vm_fault_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry) 1054 { 1055 int i; 1056 vm_offset_t addr, starta; 1057 vm_pindex_t pindex; 1058 vm_page_t m; 1059 vm_object_t object; 1060 1061 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 1062 return; 1063 1064 object = entry->object.vm_object; 1065 1066 starta = addra - PFBAK * PAGE_SIZE; 1067 if (starta < entry->start) { 1068 starta = entry->start; 1069 } else if (starta > addra) { 1070 starta = 0; 1071 } 1072 1073 for (i = 0; i < PAGEORDER_SIZE; i++) { 1074 vm_object_t backing_object, lobject; 1075 1076 addr = addra + prefault_pageorder[i]; 1077 if (addr > addra + (PFFOR * PAGE_SIZE)) 1078 addr = 0; 1079 1080 if (addr < starta || addr >= entry->end) 1081 continue; 1082 1083 if (!pmap_is_prefaultable(pmap, addr)) 1084 continue; 1085 1086 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1087 lobject = object; 1088 VM_OBJECT_LOCK(lobject); 1089 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1090 lobject->type == OBJT_DEFAULT && 1091 (backing_object = lobject->backing_object) != NULL) { 1092 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1093 0, ("vm_fault_prefault: unaligned object offset")); 1094 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1095 VM_OBJECT_LOCK(backing_object); 1096 VM_OBJECT_UNLOCK(lobject); 1097 lobject = backing_object; 1098 } 1099 /* 1100 * give-up when a page is not in memory 1101 */ 1102 if (m == NULL) { 1103 VM_OBJECT_UNLOCK(lobject); 1104 break; 1105 } 1106 if (m->valid == VM_PAGE_BITS_ALL && 1107 (m->flags & PG_FICTITIOUS) == 0) 1108 pmap_enter_quick(pmap, addr, m, entry->protection); 1109 VM_OBJECT_UNLOCK(lobject); 1110 } 1111 } 1112 1113 /* 1114 * Hold each of the physical pages that are mapped by the specified range of 1115 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid 1116 * and allow the specified types of access, "prot". If all of the implied 1117 * pages are successfully held, then the number of held pages is returned 1118 * together with pointers to those pages in the array "ma". However, if any 1119 * of the pages cannot be held, -1 is returned. 1120 */ 1121 int 1122 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len, 1123 vm_prot_t prot, vm_page_t *ma, int max_count) 1124 { 1125 vm_offset_t end, va; 1126 vm_page_t *mp; 1127 int count; 1128 boolean_t pmap_failed; 1129 1130 if (len == 0) 1131 return (0); 1132 end = round_page(addr + len); 1133 addr = trunc_page(addr); 1134 1135 /* 1136 * Check for illegal addresses. 1137 */ 1138 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map)) 1139 return (-1); 1140 1141 if (atop(end - addr) > max_count) 1142 panic("vm_fault_quick_hold_pages: count > max_count"); 1143 count = atop(end - addr); 1144 1145 /* 1146 * Most likely, the physical pages are resident in the pmap, so it is 1147 * faster to try pmap_extract_and_hold() first. 1148 */ 1149 pmap_failed = FALSE; 1150 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) { 1151 *mp = pmap_extract_and_hold(map->pmap, va, prot); 1152 if (*mp == NULL) 1153 pmap_failed = TRUE; 1154 else if ((prot & VM_PROT_WRITE) != 0 && 1155 (*mp)->dirty != VM_PAGE_BITS_ALL) { 1156 /* 1157 * Explicitly dirty the physical page. Otherwise, the 1158 * caller's changes may go unnoticed because they are 1159 * performed through an unmanaged mapping or by a DMA 1160 * operation. 1161 * 1162 * The object lock is not held here. 1163 * See vm_page_clear_dirty_mask(). 1164 */ 1165 vm_page_dirty(*mp); 1166 } 1167 } 1168 if (pmap_failed) { 1169 /* 1170 * One or more pages could not be held by the pmap. Either no 1171 * page was mapped at the specified virtual address or that 1172 * mapping had insufficient permissions. Attempt to fault in 1173 * and hold these pages. 1174 */ 1175 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) 1176 if (*mp == NULL && vm_fault_hold(map, va, prot, 1177 VM_FAULT_NORMAL, mp) != KERN_SUCCESS) 1178 goto error; 1179 } 1180 return (count); 1181 error: 1182 for (mp = ma; mp < ma + count; mp++) 1183 if (*mp != NULL) { 1184 vm_page_lock(*mp); 1185 vm_page_unhold(*mp); 1186 vm_page_unlock(*mp); 1187 } 1188 return (-1); 1189 } 1190 1191 /* 1192 * vm_fault_wire: 1193 * 1194 * Wire down a range of virtual addresses in a map. 1195 */ 1196 int 1197 vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1198 boolean_t fictitious) 1199 { 1200 vm_offset_t va; 1201 int rv; 1202 1203 /* 1204 * We simulate a fault to get the page and enter it in the physical 1205 * map. For user wiring, we only ask for read access on currently 1206 * read-only sections. 1207 */ 1208 for (va = start; va < end; va += PAGE_SIZE) { 1209 rv = vm_fault(map, va, VM_PROT_NONE, VM_FAULT_CHANGE_WIRING); 1210 if (rv) { 1211 if (va != start) 1212 vm_fault_unwire(map, start, va, fictitious); 1213 return (rv); 1214 } 1215 } 1216 return (KERN_SUCCESS); 1217 } 1218 1219 /* 1220 * vm_fault_unwire: 1221 * 1222 * Unwire a range of virtual addresses in a map. 1223 */ 1224 void 1225 vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end, 1226 boolean_t fictitious) 1227 { 1228 vm_paddr_t pa; 1229 vm_offset_t va; 1230 vm_page_t m; 1231 pmap_t pmap; 1232 1233 pmap = vm_map_pmap(map); 1234 1235 /* 1236 * Since the pages are wired down, we must be able to get their 1237 * mappings from the physical map system. 1238 */ 1239 for (va = start; va < end; va += PAGE_SIZE) { 1240 pa = pmap_extract(pmap, va); 1241 if (pa != 0) { 1242 pmap_change_wiring(pmap, va, FALSE); 1243 if (!fictitious) { 1244 m = PHYS_TO_VM_PAGE(pa); 1245 vm_page_lock(m); 1246 vm_page_unwire(m, TRUE); 1247 vm_page_unlock(m); 1248 } 1249 } 1250 } 1251 } 1252 1253 /* 1254 * Routine: 1255 * vm_fault_copy_entry 1256 * Function: 1257 * Create new shadow object backing dst_entry with private copy of 1258 * all underlying pages. When src_entry is equal to dst_entry, 1259 * function implements COW for wired-down map entry. Otherwise, 1260 * it forks wired entry into dst_map. 1261 * 1262 * In/out conditions: 1263 * The source and destination maps must be locked for write. 1264 * The source map entry must be wired down (or be a sharing map 1265 * entry corresponding to a main map entry that is wired down). 1266 */ 1267 void 1268 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1269 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1270 vm_ooffset_t *fork_charge) 1271 { 1272 vm_object_t backing_object, dst_object, object, src_object; 1273 vm_pindex_t dst_pindex, pindex, src_pindex; 1274 vm_prot_t access, prot; 1275 vm_offset_t vaddr; 1276 vm_page_t dst_m; 1277 vm_page_t src_m; 1278 boolean_t upgrade; 1279 1280 #ifdef lint 1281 src_map++; 1282 #endif /* lint */ 1283 1284 upgrade = src_entry == dst_entry; 1285 1286 src_object = src_entry->object.vm_object; 1287 src_pindex = OFF_TO_IDX(src_entry->offset); 1288 1289 /* 1290 * Create the top-level object for the destination entry. (Doesn't 1291 * actually shadow anything - we copy the pages directly.) 1292 */ 1293 dst_object = vm_object_allocate(OBJT_DEFAULT, 1294 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1295 #if VM_NRESERVLEVEL > 0 1296 dst_object->flags |= OBJ_COLORED; 1297 dst_object->pg_color = atop(dst_entry->start); 1298 #endif 1299 1300 VM_OBJECT_LOCK(dst_object); 1301 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1302 ("vm_fault_copy_entry: vm_object not NULL")); 1303 dst_entry->object.vm_object = dst_object; 1304 dst_entry->offset = 0; 1305 dst_object->charge = dst_entry->end - dst_entry->start; 1306 if (fork_charge != NULL) { 1307 KASSERT(dst_entry->cred == NULL, 1308 ("vm_fault_copy_entry: leaked swp charge")); 1309 dst_object->cred = curthread->td_ucred; 1310 crhold(dst_object->cred); 1311 *fork_charge += dst_object->charge; 1312 } else { 1313 dst_object->cred = dst_entry->cred; 1314 dst_entry->cred = NULL; 1315 } 1316 access = prot = dst_entry->protection; 1317 /* 1318 * If not an upgrade, then enter the mappings in the pmap as 1319 * read and/or execute accesses. Otherwise, enter them as 1320 * write accesses. 1321 * 1322 * A writeable large page mapping is only created if all of 1323 * the constituent small page mappings are modified. Marking 1324 * PTEs as modified on inception allows promotion to happen 1325 * without taking potentially large number of soft faults. 1326 */ 1327 if (!upgrade) 1328 access &= ~VM_PROT_WRITE; 1329 1330 /* 1331 * Loop through all of the virtual pages within the entry's 1332 * range, copying each page from the source object to the 1333 * destination object. Since the source is wired, those pages 1334 * must exist. In contrast, the destination is pageable. 1335 * Since the destination object does share any backing storage 1336 * with the source object, all of its pages must be dirtied, 1337 * regardless of whether they can be written. 1338 */ 1339 for (vaddr = dst_entry->start, dst_pindex = 0; 1340 vaddr < dst_entry->end; 1341 vaddr += PAGE_SIZE, dst_pindex++) { 1342 1343 /* 1344 * Allocate a page in the destination object. 1345 */ 1346 do { 1347 dst_m = vm_page_alloc(dst_object, dst_pindex, 1348 VM_ALLOC_NORMAL); 1349 if (dst_m == NULL) { 1350 VM_OBJECT_UNLOCK(dst_object); 1351 VM_WAIT; 1352 VM_OBJECT_LOCK(dst_object); 1353 } 1354 } while (dst_m == NULL); 1355 1356 /* 1357 * Find the page in the source object, and copy it in. 1358 * Because the source is wired down, the page will be 1359 * in memory. 1360 */ 1361 VM_OBJECT_LOCK(src_object); 1362 object = src_object; 1363 pindex = src_pindex + dst_pindex; 1364 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1365 (backing_object = object->backing_object) != NULL) { 1366 /* 1367 * Unless the source mapping is read-only or 1368 * it is presently being upgraded from 1369 * read-only, the first object in the shadow 1370 * chain should provide all of the pages. In 1371 * other words, this loop body should never be 1372 * executed when the source mapping is already 1373 * read/write. 1374 */ 1375 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 || 1376 upgrade, 1377 ("vm_fault_copy_entry: main object missing page")); 1378 1379 VM_OBJECT_LOCK(backing_object); 1380 pindex += OFF_TO_IDX(object->backing_object_offset); 1381 VM_OBJECT_UNLOCK(object); 1382 object = backing_object; 1383 } 1384 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing")); 1385 pmap_copy_page(src_m, dst_m); 1386 VM_OBJECT_UNLOCK(object); 1387 dst_m->valid = VM_PAGE_BITS_ALL; 1388 dst_m->dirty = VM_PAGE_BITS_ALL; 1389 VM_OBJECT_UNLOCK(dst_object); 1390 1391 /* 1392 * Enter it in the pmap. If a wired, copy-on-write 1393 * mapping is being replaced by a write-enabled 1394 * mapping, then wire that new mapping. 1395 */ 1396 pmap_enter(dst_map->pmap, vaddr, access, dst_m, prot, upgrade); 1397 1398 /* 1399 * Mark it no longer busy, and put it on the active list. 1400 */ 1401 VM_OBJECT_LOCK(dst_object); 1402 1403 if (upgrade) { 1404 vm_page_lock(src_m); 1405 vm_page_unwire(src_m, 0); 1406 vm_page_unlock(src_m); 1407 1408 vm_page_lock(dst_m); 1409 vm_page_wire(dst_m); 1410 vm_page_unlock(dst_m); 1411 } else { 1412 vm_page_lock(dst_m); 1413 vm_page_activate(dst_m); 1414 vm_page_unlock(dst_m); 1415 } 1416 vm_page_wakeup(dst_m); 1417 } 1418 VM_OBJECT_UNLOCK(dst_object); 1419 if (upgrade) { 1420 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1421 vm_object_deallocate(src_object); 1422 } 1423 } 1424 1425 1426 /* 1427 * This routine checks around the requested page for other pages that 1428 * might be able to be faulted in. This routine brackets the viable 1429 * pages for the pages to be paged in. 1430 * 1431 * Inputs: 1432 * m, rbehind, rahead 1433 * 1434 * Outputs: 1435 * marray (array of vm_page_t), reqpage (index of requested page) 1436 * 1437 * Return value: 1438 * number of pages in marray 1439 */ 1440 static int 1441 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1442 vm_page_t m; 1443 int rbehind; 1444 int rahead; 1445 vm_page_t *marray; 1446 int *reqpage; 1447 { 1448 int i,j; 1449 vm_object_t object; 1450 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1451 vm_page_t rtm; 1452 int cbehind, cahead; 1453 1454 VM_OBJECT_LOCK_ASSERT(m->object, MA_OWNED); 1455 1456 object = m->object; 1457 pindex = m->pindex; 1458 cbehind = cahead = 0; 1459 1460 /* 1461 * if the requested page is not available, then give up now 1462 */ 1463 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1464 return 0; 1465 } 1466 1467 if ((cbehind == 0) && (cahead == 0)) { 1468 *reqpage = 0; 1469 marray[0] = m; 1470 return 1; 1471 } 1472 1473 if (rahead > cahead) { 1474 rahead = cahead; 1475 } 1476 1477 if (rbehind > cbehind) { 1478 rbehind = cbehind; 1479 } 1480 1481 /* 1482 * scan backward for the read behind pages -- in memory 1483 */ 1484 if (pindex > 0) { 1485 if (rbehind > pindex) { 1486 rbehind = pindex; 1487 startpindex = 0; 1488 } else { 1489 startpindex = pindex - rbehind; 1490 } 1491 1492 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1493 rtm->pindex >= startpindex) 1494 startpindex = rtm->pindex + 1; 1495 1496 /* tpindex is unsigned; beware of numeric underflow. */ 1497 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1498 tpindex < pindex; i++, tpindex--) { 1499 1500 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1501 VM_ALLOC_IFNOTCACHED); 1502 if (rtm == NULL) { 1503 /* 1504 * Shift the allocated pages to the 1505 * beginning of the array. 1506 */ 1507 for (j = 0; j < i; j++) { 1508 marray[j] = marray[j + tpindex + 1 - 1509 startpindex]; 1510 } 1511 break; 1512 } 1513 1514 marray[tpindex - startpindex] = rtm; 1515 } 1516 } else { 1517 startpindex = 0; 1518 i = 0; 1519 } 1520 1521 marray[i] = m; 1522 /* page offset of the required page */ 1523 *reqpage = i; 1524 1525 tpindex = pindex + 1; 1526 i++; 1527 1528 /* 1529 * scan forward for the read ahead pages 1530 */ 1531 endpindex = tpindex + rahead; 1532 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1533 endpindex = rtm->pindex; 1534 if (endpindex > object->size) 1535 endpindex = object->size; 1536 1537 for (; tpindex < endpindex; i++, tpindex++) { 1538 1539 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1540 VM_ALLOC_IFNOTCACHED); 1541 if (rtm == NULL) { 1542 break; 1543 } 1544 1545 marray[i] = rtm; 1546 } 1547 1548 /* return number of pages */ 1549 return i; 1550 } 1551 1552 /* 1553 * Block entry into the machine-independent layer's page fault handler by 1554 * the calling thread. Subsequent calls to vm_fault() by that thread will 1555 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of 1556 * spurious page faults. 1557 */ 1558 int 1559 vm_fault_disable_pagefaults(void) 1560 { 1561 1562 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR)); 1563 } 1564 1565 void 1566 vm_fault_enable_pagefaults(int save) 1567 { 1568 1569 curthread_pflags_restore(save); 1570 }
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