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 * $FreeBSD$ 70 */ 71 72 /* 73 * Page fault handling module. 74 */ 75 76 #include <sys/param.h> 77 #include <sys/systm.h> 78 #include <sys/kernel.h> 79 #include <sys/lock.h> 80 #include <sys/mutex.h> 81 #include <sys/proc.h> 82 #include <sys/resourcevar.h> 83 #include <sys/sysctl.h> 84 #include <sys/vmmeter.h> 85 #include <sys/vnode.h> 86 87 #include <vm/vm.h> 88 #include <vm/vm_param.h> 89 #include <vm/pmap.h> 90 #include <vm/vm_map.h> 91 #include <vm/vm_object.h> 92 #include <vm/vm_page.h> 93 #include <vm/vm_pageout.h> 94 #include <vm/vm_kern.h> 95 #include <vm/vm_pager.h> 96 #include <vm/vnode_pager.h> 97 #include <vm/vm_extern.h> 98 99 static int vm_fault_additional_pages __P((vm_page_t, int, 100 int, vm_page_t *, int *)); 101 102 #define VM_FAULT_READ_AHEAD 8 103 #define VM_FAULT_READ_BEHIND 7 104 #define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1) 105 106 struct faultstate { 107 vm_page_t m; 108 vm_object_t object; 109 vm_pindex_t pindex; 110 vm_page_t first_m; 111 vm_object_t first_object; 112 vm_pindex_t first_pindex; 113 vm_map_t map; 114 vm_map_entry_t entry; 115 int lookup_still_valid; 116 struct vnode *vp; 117 }; 118 119 static __inline void 120 release_page(struct faultstate *fs) 121 { 122 vm_page_wakeup(fs->m); 123 vm_page_deactivate(fs->m); 124 fs->m = NULL; 125 } 126 127 static __inline void 128 unlock_map(struct faultstate *fs) 129 { 130 if (fs->lookup_still_valid) { 131 vm_map_lookup_done(fs->map, fs->entry); 132 fs->lookup_still_valid = FALSE; 133 } 134 } 135 136 static void 137 _unlock_things(struct faultstate *fs, int dealloc) 138 { 139 GIANT_REQUIRED; 140 vm_object_pip_wakeup(fs->object); 141 if (fs->object != fs->first_object) { 142 vm_page_free(fs->first_m); 143 vm_object_pip_wakeup(fs->first_object); 144 fs->first_m = NULL; 145 } 146 if (dealloc) { 147 vm_object_deallocate(fs->first_object); 148 } 149 unlock_map(fs); 150 if (fs->vp != NULL) { 151 vput(fs->vp); 152 fs->vp = NULL; 153 } 154 } 155 156 #define unlock_things(fs) _unlock_things(fs, 0) 157 #define unlock_and_deallocate(fs) _unlock_things(fs, 1) 158 159 /* 160 * TRYPAGER - used by vm_fault to calculate whether the pager for the 161 * current object *might* contain the page. 162 * 163 * default objects are zero-fill, there is no real pager. 164 */ 165 166 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 167 (((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired)) 168 169 /* 170 * vm_fault: 171 * 172 * Handle a page fault occurring at the given address, 173 * requiring the given permissions, in the map specified. 174 * If successful, the page is inserted into the 175 * associated physical map. 176 * 177 * NOTE: the given address should be truncated to the 178 * proper page address. 179 * 180 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 181 * a standard error specifying why the fault is fatal is returned. 182 * 183 * 184 * The map in question must be referenced, and remains so. 185 * Caller may hold no locks. 186 */ 187 static int vm_fault1 __P((vm_map_t, vm_offset_t, vm_prot_t, int)); 188 189 int 190 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 191 int fault_flags) 192 { 193 int ret; 194 195 mtx_lock(&Giant); 196 /* GIANT_REQUIRED */ 197 198 ret = vm_fault1(map, vaddr, fault_type, fault_flags); 199 mtx_unlock(&Giant); 200 return (ret); 201 } 202 203 static int 204 vm_fault1(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 205 int fault_flags) 206 { 207 vm_prot_t prot; 208 int result; 209 boolean_t wired; 210 int map_generation; 211 vm_object_t next_object; 212 vm_page_t marray[VM_FAULT_READ]; 213 int hardfault; 214 int faultcount; 215 struct faultstate fs; 216 217 GIANT_REQUIRED; 218 219 cnt.v_vm_faults++; 220 hardfault = 0; 221 222 RetryFault:; 223 224 /* 225 * Find the backing store object and offset into it to begin the 226 * search. 227 */ 228 fs.map = map; 229 if ((result = vm_map_lookup(&fs.map, vaddr, 230 fault_type, &fs.entry, &fs.first_object, 231 &fs.first_pindex, &prot, &wired)) != KERN_SUCCESS) { 232 if ((result != KERN_PROTECTION_FAILURE) || 233 ((fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE)) { 234 return result; 235 } 236 237 /* 238 * If we are user-wiring a r/w segment, and it is COW, then 239 * we need to do the COW operation. Note that we don't COW 240 * currently RO sections now, because it is NOT desirable 241 * to COW .text. We simply keep .text from ever being COW'ed 242 * and take the heat that one cannot debug wired .text sections. 243 */ 244 result = vm_map_lookup(&fs.map, vaddr, 245 VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE, 246 &fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired); 247 if (result != KERN_SUCCESS) { 248 return result; 249 } 250 251 /* 252 * If we don't COW now, on a user wire, the user will never 253 * be able to write to the mapping. If we don't make this 254 * restriction, the bookkeeping would be nearly impossible. 255 */ 256 if ((fs.entry->protection & VM_PROT_WRITE) == 0) 257 fs.entry->max_protection &= ~VM_PROT_WRITE; 258 } 259 260 map_generation = fs.map->timestamp; 261 262 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 263 panic("vm_fault: fault on nofault entry, addr: %lx", 264 (u_long)vaddr); 265 } 266 267 /* 268 * Make a reference to this object to prevent its disposal while we 269 * are messing with it. Once we have the reference, the map is free 270 * to be diddled. Since objects reference their shadows (and copies), 271 * they will stay around as well. 272 */ 273 vm_object_reference(fs.first_object); 274 vm_object_pip_add(fs.first_object, 1); 275 276 fs.vp = vnode_pager_lock(fs.first_object); 277 if ((fault_type & VM_PROT_WRITE) && 278 (fs.first_object->type == OBJT_VNODE)) { 279 vm_freeze_copyopts(fs.first_object, 280 fs.first_pindex, fs.first_pindex + 1); 281 } 282 283 fs.lookup_still_valid = TRUE; 284 285 if (wired) 286 fault_type = prot; 287 288 fs.first_m = NULL; 289 290 /* 291 * Search for the page at object/offset. 292 */ 293 294 fs.object = fs.first_object; 295 fs.pindex = fs.first_pindex; 296 297 while (TRUE) { 298 /* 299 * If the object is dead, we stop here 300 */ 301 302 if (fs.object->flags & OBJ_DEAD) { 303 unlock_and_deallocate(&fs); 304 return (KERN_PROTECTION_FAILURE); 305 } 306 307 /* 308 * See if page is resident 309 */ 310 311 fs.m = vm_page_lookup(fs.object, fs.pindex); 312 if (fs.m != NULL) { 313 int queue, s; 314 /* 315 * Wait/Retry if the page is busy. We have to do this 316 * if the page is busy via either PG_BUSY or 317 * vm_page_t->busy because the vm_pager may be using 318 * vm_page_t->busy for pageouts ( and even pageins if 319 * it is the vnode pager ), and we could end up trying 320 * to pagein and pageout the same page simultaneously. 321 * 322 * We can theoretically allow the busy case on a read 323 * fault if the page is marked valid, but since such 324 * pages are typically already pmap'd, putting that 325 * special case in might be more effort then it is 326 * worth. We cannot under any circumstances mess 327 * around with a vm_page_t->busy page except, perhaps, 328 * to pmap it. 329 */ 330 if ((fs.m->flags & PG_BUSY) || fs.m->busy) { 331 unlock_things(&fs); 332 (void)vm_page_sleep_busy(fs.m, TRUE, "vmpfw"); 333 cnt.v_intrans++; 334 vm_object_deallocate(fs.first_object); 335 goto RetryFault; 336 } 337 338 queue = fs.m->queue; 339 s = splvm(); 340 vm_pageq_remove_nowakeup(fs.m); 341 splx(s); 342 343 if ((queue - fs.m->pc) == PQ_CACHE && vm_page_count_severe()) { 344 vm_page_activate(fs.m); 345 unlock_and_deallocate(&fs); 346 VM_WAIT; 347 goto RetryFault; 348 } 349 350 /* 351 * Mark page busy for other processes, and the 352 * pagedaemon. If it still isn't completely valid 353 * (readable), jump to readrest, else break-out ( we 354 * found the page ). 355 */ 356 357 vm_page_busy(fs.m); 358 if (((fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) && 359 fs.m->object != kernel_object && fs.m->object != kmem_object) { 360 goto readrest; 361 } 362 363 break; 364 } 365 366 /* 367 * Page is not resident, If this is the search termination 368 * or the pager might contain the page, allocate a new page. 369 */ 370 371 if (TRYPAGER || fs.object == fs.first_object) { 372 if (fs.pindex >= fs.object->size) { 373 unlock_and_deallocate(&fs); 374 return (KERN_PROTECTION_FAILURE); 375 } 376 377 /* 378 * Allocate a new page for this object/offset pair. 379 */ 380 fs.m = NULL; 381 if (!vm_page_count_severe()) { 382 fs.m = vm_page_alloc(fs.object, fs.pindex, 383 (fs.vp || fs.object->backing_object)? VM_ALLOC_NORMAL: VM_ALLOC_ZERO); 384 } 385 if (fs.m == NULL) { 386 unlock_and_deallocate(&fs); 387 VM_WAIT; 388 goto RetryFault; 389 } 390 } 391 392 readrest: 393 /* 394 * We have found a valid page or we have allocated a new page. 395 * The page thus may not be valid or may not be entirely 396 * valid. 397 * 398 * Attempt to fault-in the page if there is a chance that the 399 * pager has it, and potentially fault in additional pages 400 * at the same time. 401 */ 402 403 if (TRYPAGER) { 404 int rv; 405 int reqpage; 406 int ahead, behind; 407 u_char behavior = vm_map_entry_behavior(fs.entry); 408 409 if (behavior == MAP_ENTRY_BEHAV_RANDOM) { 410 ahead = 0; 411 behind = 0; 412 } else { 413 behind = (vaddr - fs.entry->start) >> PAGE_SHIFT; 414 if (behind > VM_FAULT_READ_BEHIND) 415 behind = VM_FAULT_READ_BEHIND; 416 417 ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1; 418 if (ahead > VM_FAULT_READ_AHEAD) 419 ahead = VM_FAULT_READ_AHEAD; 420 } 421 422 if ((fs.first_object->type != OBJT_DEVICE) && 423 (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL || 424 (behavior != MAP_ENTRY_BEHAV_RANDOM && 425 fs.pindex >= fs.entry->lastr && 426 fs.pindex < fs.entry->lastr + VM_FAULT_READ)) 427 ) { 428 vm_pindex_t firstpindex, tmppindex; 429 430 if (fs.first_pindex < 2 * VM_FAULT_READ) 431 firstpindex = 0; 432 else 433 firstpindex = fs.first_pindex - 2 * VM_FAULT_READ; 434 435 /* 436 * note: partially valid pages cannot be 437 * included in the lookahead - NFS piecemeal 438 * writes will barf on it badly. 439 */ 440 441 for(tmppindex = fs.first_pindex - 1; 442 tmppindex >= firstpindex; 443 --tmppindex) { 444 vm_page_t mt; 445 mt = vm_page_lookup( fs.first_object, tmppindex); 446 if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL)) 447 break; 448 if (mt->busy || 449 (mt->flags & (PG_BUSY | PG_FICTITIOUS | PG_UNMANAGED)) || 450 mt->hold_count || 451 mt->wire_count) 452 continue; 453 if (mt->dirty == 0) 454 vm_page_test_dirty(mt); 455 if (mt->dirty) { 456 vm_page_protect(mt, VM_PROT_NONE); 457 vm_page_deactivate(mt); 458 } else { 459 vm_page_cache(mt); 460 } 461 } 462 463 ahead += behind; 464 behind = 0; 465 } 466 467 /* 468 * now we find out if any other pages should be paged 469 * in at this time this routine checks to see if the 470 * pages surrounding this fault reside in the same 471 * object as the page for this fault. If they do, 472 * then they are faulted in also into the object. The 473 * array "marray" returned contains an array of 474 * vm_page_t structs where one of them is the 475 * vm_page_t passed to the routine. The reqpage 476 * return value is the index into the marray for the 477 * vm_page_t passed to the routine. 478 * 479 * fs.m plus the additional pages are PG_BUSY'd. 480 */ 481 faultcount = vm_fault_additional_pages( 482 fs.m, behind, ahead, marray, &reqpage); 483 484 /* 485 * update lastr imperfectly (we do not know how much 486 * getpages will actually read), but good enough. 487 */ 488 fs.entry->lastr = fs.pindex + faultcount - behind; 489 490 /* 491 * Call the pager to retrieve the data, if any, after 492 * releasing the lock on the map. We hold a ref on 493 * fs.object and the pages are PG_BUSY'd. 494 */ 495 unlock_map(&fs); 496 497 rv = faultcount ? 498 vm_pager_get_pages(fs.object, marray, faultcount, 499 reqpage) : VM_PAGER_FAIL; 500 501 if (rv == VM_PAGER_OK) { 502 /* 503 * Found the page. Leave it busy while we play 504 * with it. 505 */ 506 507 /* 508 * Relookup in case pager changed page. Pager 509 * is responsible for disposition of old page 510 * if moved. 511 */ 512 fs.m = vm_page_lookup(fs.object, fs.pindex); 513 if(!fs.m) { 514 unlock_and_deallocate(&fs); 515 goto RetryFault; 516 } 517 518 hardfault++; 519 break; /* break to PAGE HAS BEEN FOUND */ 520 } 521 /* 522 * Remove the bogus page (which does not exist at this 523 * object/offset); before doing so, we must get back 524 * our object lock to preserve our invariant. 525 * 526 * Also wake up any other process that may want to bring 527 * in this page. 528 * 529 * If this is the top-level object, we must leave the 530 * busy page to prevent another process from rushing 531 * past us, and inserting the page in that object at 532 * the same time that we are. 533 */ 534 535 if (rv == VM_PAGER_ERROR) 536 printf("vm_fault: pager read error, pid %d (%s)\n", 537 curproc->p_pid, curproc->p_comm); 538 /* 539 * Data outside the range of the pager or an I/O error 540 */ 541 /* 542 * XXX - the check for kernel_map is a kludge to work 543 * around having the machine panic on a kernel space 544 * fault w/ I/O error. 545 */ 546 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 547 (rv == VM_PAGER_BAD)) { 548 vm_page_free(fs.m); 549 fs.m = NULL; 550 unlock_and_deallocate(&fs); 551 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 552 } 553 if (fs.object != fs.first_object) { 554 vm_page_free(fs.m); 555 fs.m = NULL; 556 /* 557 * XXX - we cannot just fall out at this 558 * point, m has been freed and is invalid! 559 */ 560 } 561 } 562 563 /* 564 * We get here if the object has default pager (or unwiring) 565 * or the pager doesn't have the page. 566 */ 567 if (fs.object == fs.first_object) 568 fs.first_m = fs.m; 569 570 /* 571 * Move on to the next object. Lock the next object before 572 * unlocking the current one. 573 */ 574 575 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 576 next_object = fs.object->backing_object; 577 if (next_object == NULL) { 578 /* 579 * If there's no object left, fill the page in the top 580 * object with zeros. 581 */ 582 if (fs.object != fs.first_object) { 583 vm_object_pip_wakeup(fs.object); 584 585 fs.object = fs.first_object; 586 fs.pindex = fs.first_pindex; 587 fs.m = fs.first_m; 588 } 589 fs.first_m = NULL; 590 591 /* 592 * Zero the page if necessary and mark it valid. 593 */ 594 if ((fs.m->flags & PG_ZERO) == 0) { 595 vm_page_zero_fill(fs.m); 596 } else { 597 cnt.v_ozfod++; 598 } 599 cnt.v_zfod++; 600 fs.m->valid = VM_PAGE_BITS_ALL; 601 break; /* break to PAGE HAS BEEN FOUND */ 602 } else { 603 if (fs.object != fs.first_object) { 604 vm_object_pip_wakeup(fs.object); 605 } 606 KASSERT(fs.object != next_object, ("object loop %p", next_object)); 607 fs.object = next_object; 608 vm_object_pip_add(fs.object, 1); 609 } 610 } 611 612 KASSERT((fs.m->flags & PG_BUSY) != 0, 613 ("vm_fault: not busy after main loop")); 614 615 /* 616 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 617 * is held.] 618 */ 619 620 /* 621 * If the page is being written, but isn't already owned by the 622 * top-level object, we have to copy it into a new page owned by the 623 * top-level object. 624 */ 625 626 if (fs.object != fs.first_object) { 627 /* 628 * We only really need to copy if we want to write it. 629 */ 630 631 if (fault_type & VM_PROT_WRITE) { 632 /* 633 * This allows pages to be virtually copied from a 634 * backing_object into the first_object, where the 635 * backing object has no other refs to it, and cannot 636 * gain any more refs. Instead of a bcopy, we just 637 * move the page from the backing object to the 638 * first object. Note that we must mark the page 639 * dirty in the first object so that it will go out 640 * to swap when needed. 641 */ 642 if (map_generation == fs.map->timestamp && 643 /* 644 * Only one shadow object 645 */ 646 (fs.object->shadow_count == 1) && 647 /* 648 * No COW refs, except us 649 */ 650 (fs.object->ref_count == 1) && 651 /* 652 * No one else can look this object up 653 */ 654 (fs.object->handle == NULL) && 655 /* 656 * No other ways to look the object up 657 */ 658 ((fs.object->type == OBJT_DEFAULT) || 659 (fs.object->type == OBJT_SWAP)) && 660 /* 661 * We don't chase down the shadow chain 662 */ 663 (fs.object == fs.first_object->backing_object) && 664 665 /* 666 * grab the lock if we need to 667 */ 668 (fs.lookup_still_valid || 669 lockmgr(&fs.map->lock, LK_EXCLUSIVE|LK_NOWAIT, (void *)0, curthread) == 0) 670 ) { 671 672 fs.lookup_still_valid = 1; 673 /* 674 * get rid of the unnecessary page 675 */ 676 vm_page_protect(fs.first_m, VM_PROT_NONE); 677 vm_page_free(fs.first_m); 678 fs.first_m = NULL; 679 680 /* 681 * grab the page and put it into the 682 * process'es object. The page is 683 * automatically made dirty. 684 */ 685 vm_page_rename(fs.m, fs.first_object, fs.first_pindex); 686 fs.first_m = fs.m; 687 vm_page_busy(fs.first_m); 688 fs.m = NULL; 689 cnt.v_cow_optim++; 690 } else { 691 /* 692 * Oh, well, lets copy it. 693 */ 694 vm_page_copy(fs.m, fs.first_m); 695 } 696 697 if (fs.m) { 698 /* 699 * We no longer need the old page or object. 700 */ 701 release_page(&fs); 702 } 703 704 /* 705 * fs.object != fs.first_object due to above 706 * conditional 707 */ 708 709 vm_object_pip_wakeup(fs.object); 710 711 /* 712 * Only use the new page below... 713 */ 714 715 cnt.v_cow_faults++; 716 fs.m = fs.first_m; 717 fs.object = fs.first_object; 718 fs.pindex = fs.first_pindex; 719 720 } else { 721 prot &= ~VM_PROT_WRITE; 722 } 723 } 724 725 /* 726 * We must verify that the maps have not changed since our last 727 * lookup. 728 */ 729 730 if (!fs.lookup_still_valid && 731 (fs.map->timestamp != map_generation)) { 732 vm_object_t retry_object; 733 vm_pindex_t retry_pindex; 734 vm_prot_t retry_prot; 735 736 /* 737 * Since map entries may be pageable, make sure we can take a 738 * page fault on them. 739 */ 740 741 /* 742 * Unlock vnode before the lookup to avoid deadlock. E.G. 743 * avoid a deadlock between the inode and exec_map that can 744 * occur due to locks being obtained in different orders. 745 */ 746 747 if (fs.vp != NULL) { 748 vput(fs.vp); 749 fs.vp = NULL; 750 } 751 752 if (fs.map->infork) { 753 release_page(&fs); 754 unlock_and_deallocate(&fs); 755 goto RetryFault; 756 } 757 758 /* 759 * To avoid trying to write_lock the map while another process 760 * has it read_locked (in vm_map_pageable), we do not try for 761 * write permission. If the page is still writable, we will 762 * get write permission. If it is not, or has been marked 763 * needs_copy, we enter the mapping without write permission, 764 * and will merely take another fault. 765 */ 766 result = vm_map_lookup(&fs.map, vaddr, fault_type & ~VM_PROT_WRITE, 767 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 768 map_generation = fs.map->timestamp; 769 770 /* 771 * If we don't need the page any longer, put it on the active 772 * list (the easiest thing to do here). If no one needs it, 773 * pageout will grab it eventually. 774 */ 775 776 if (result != KERN_SUCCESS) { 777 release_page(&fs); 778 unlock_and_deallocate(&fs); 779 return (result); 780 } 781 fs.lookup_still_valid = TRUE; 782 783 if ((retry_object != fs.first_object) || 784 (retry_pindex != fs.first_pindex)) { 785 release_page(&fs); 786 unlock_and_deallocate(&fs); 787 goto RetryFault; 788 } 789 /* 790 * Check whether the protection has changed or the object has 791 * been copied while we left the map unlocked. Changing from 792 * read to write permission is OK - we leave the page 793 * write-protected, and catch the write fault. Changing from 794 * write to read permission means that we can't mark the page 795 * write-enabled after all. 796 */ 797 prot &= retry_prot; 798 } 799 800 /* 801 * Put this page into the physical map. We had to do the unlock above 802 * because pmap_enter may cause other faults. We don't put the page 803 * back on the active queue until later so that the page-out daemon 804 * won't find us (yet). 805 */ 806 807 if (prot & VM_PROT_WRITE) { 808 vm_page_flag_set(fs.m, PG_WRITEABLE); 809 vm_object_set_flag(fs.m->object, 810 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 811 812 /* 813 * If the fault is a write, we know that this page is being 814 * written NOW so dirty it explicitly to save on 815 * pmap_is_modified() calls later. 816 * 817 * If this is a NOSYNC mmap we do not want to set PG_NOSYNC 818 * if the page is already dirty to prevent data written with 819 * the expectation of being synced from not being synced. 820 * Likewise if this entry does not request NOSYNC then make 821 * sure the page isn't marked NOSYNC. Applications sharing 822 * data should use the same flags to avoid ping ponging. 823 * 824 * Also tell the backing pager, if any, that it should remove 825 * any swap backing since the page is now dirty. 826 */ 827 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 828 if (fs.m->dirty == 0) 829 vm_page_flag_set(fs.m, PG_NOSYNC); 830 } else { 831 vm_page_flag_clear(fs.m, PG_NOSYNC); 832 } 833 if (fault_flags & VM_FAULT_DIRTY) { 834 int s; 835 vm_page_dirty(fs.m); 836 s = splvm(); 837 vm_pager_page_unswapped(fs.m); 838 splx(s); 839 } 840 } 841 842 /* 843 * Page had better still be busy 844 */ 845 846 KASSERT(fs.m->flags & PG_BUSY, 847 ("vm_fault: page %p not busy!", fs.m)); 848 849 unlock_things(&fs); 850 851 /* 852 * Sanity check: page must be completely valid or it is not fit to 853 * map into user space. vm_pager_get_pages() ensures this. 854 */ 855 856 if (fs.m->valid != VM_PAGE_BITS_ALL) { 857 vm_page_zero_invalid(fs.m, TRUE); 858 printf("Warning: page %p partially invalid on fault\n", fs.m); 859 } 860 861 pmap_enter(fs.map->pmap, vaddr, fs.m, prot, wired); 862 863 if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) { 864 pmap_prefault(fs.map->pmap, vaddr, fs.entry); 865 } 866 867 vm_page_flag_clear(fs.m, PG_ZERO); 868 vm_page_flag_set(fs.m, PG_MAPPED|PG_REFERENCED); 869 if (fault_flags & VM_FAULT_HOLD) 870 vm_page_hold(fs.m); 871 872 /* 873 * If the page is not wired down, then put it where the pageout daemon 874 * can find it. 875 */ 876 877 if (fault_flags & VM_FAULT_WIRE_MASK) { 878 if (wired) 879 vm_page_wire(fs.m); 880 else 881 vm_page_unwire(fs.m, 1); 882 } else { 883 vm_page_activate(fs.m); 884 } 885 886 mtx_lock_spin(&sched_lock); 887 if (curproc && (curproc->p_sflag & PS_INMEM) && curproc->p_stats) { 888 if (hardfault) { 889 curproc->p_stats->p_ru.ru_majflt++; 890 } else { 891 curproc->p_stats->p_ru.ru_minflt++; 892 } 893 } 894 mtx_unlock_spin(&sched_lock); 895 896 /* 897 * Unlock everything, and return 898 */ 899 900 vm_page_wakeup(fs.m); 901 vm_object_deallocate(fs.first_object); 902 903 return (KERN_SUCCESS); 904 905 } 906 907 /* 908 * vm_fault_wire: 909 * 910 * Wire down a range of virtual addresses in a map. 911 */ 912 int 913 vm_fault_wire(map, start, end) 914 vm_map_t map; 915 vm_offset_t start, end; 916 { 917 918 vm_offset_t va; 919 pmap_t pmap; 920 int rv; 921 922 pmap = vm_map_pmap(map); 923 924 /* 925 * Inform the physical mapping system that the range of addresses may 926 * not fault, so that page tables and such can be locked down as well. 927 */ 928 929 pmap_pageable(pmap, start, end, FALSE); 930 931 /* 932 * We simulate a fault to get the page and enter it in the physical 933 * map. 934 */ 935 936 for (va = start; va < end; va += PAGE_SIZE) { 937 rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE, 938 VM_FAULT_CHANGE_WIRING); 939 if (rv) { 940 if (va != start) 941 vm_fault_unwire(map, start, va); 942 return (rv); 943 } 944 } 945 return (KERN_SUCCESS); 946 } 947 948 /* 949 * vm_fault_user_wire: 950 * 951 * Wire down a range of virtual addresses in a map. This 952 * is for user mode though, so we only ask for read access 953 * on currently read only sections. 954 */ 955 int 956 vm_fault_user_wire(map, start, end) 957 vm_map_t map; 958 vm_offset_t start, end; 959 { 960 961 vm_offset_t va; 962 pmap_t pmap; 963 int rv; 964 965 GIANT_REQUIRED; 966 967 pmap = vm_map_pmap(map); 968 969 /* 970 * Inform the physical mapping system that the range of addresses may 971 * not fault, so that page tables and such can be locked down as well. 972 */ 973 974 pmap_pageable(pmap, start, end, FALSE); 975 976 /* 977 * We simulate a fault to get the page and enter it in the physical 978 * map. 979 */ 980 for (va = start; va < end; va += PAGE_SIZE) { 981 rv = vm_fault(map, va, VM_PROT_READ, VM_FAULT_USER_WIRE); 982 if (rv) { 983 if (va != start) 984 vm_fault_unwire(map, start, va); 985 return (rv); 986 } 987 } 988 return (KERN_SUCCESS); 989 } 990 991 992 /* 993 * vm_fault_unwire: 994 * 995 * Unwire a range of virtual addresses in a map. 996 */ 997 void 998 vm_fault_unwire(map, start, end) 999 vm_map_t map; 1000 vm_offset_t start, end; 1001 { 1002 1003 vm_offset_t va, pa; 1004 pmap_t pmap; 1005 1006 pmap = vm_map_pmap(map); 1007 1008 /* 1009 * Since the pages are wired down, we must be able to get their 1010 * mappings from the physical map system. 1011 */ 1012 1013 for (va = start; va < end; va += PAGE_SIZE) { 1014 pa = pmap_extract(pmap, va); 1015 if (pa != (vm_offset_t) 0) { 1016 pmap_change_wiring(pmap, va, FALSE); 1017 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1); 1018 } 1019 } 1020 1021 /* 1022 * Inform the physical mapping system that the range of addresses may 1023 * fault, so that page tables and such may be unwired themselves. 1024 */ 1025 1026 pmap_pageable(pmap, start, end, TRUE); 1027 1028 } 1029 1030 /* 1031 * Routine: 1032 * vm_fault_copy_entry 1033 * Function: 1034 * Copy all of the pages from a wired-down map entry to another. 1035 * 1036 * In/out conditions: 1037 * The source and destination maps must be locked for write. 1038 * The source map entry must be wired down (or be a sharing map 1039 * entry corresponding to a main map entry that is wired down). 1040 */ 1041 1042 void 1043 vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry) 1044 vm_map_t dst_map; 1045 vm_map_t src_map; 1046 vm_map_entry_t dst_entry; 1047 vm_map_entry_t src_entry; 1048 { 1049 vm_object_t dst_object; 1050 vm_object_t src_object; 1051 vm_ooffset_t dst_offset; 1052 vm_ooffset_t src_offset; 1053 vm_prot_t prot; 1054 vm_offset_t vaddr; 1055 vm_page_t dst_m; 1056 vm_page_t src_m; 1057 1058 #ifdef lint 1059 src_map++; 1060 #endif /* lint */ 1061 1062 src_object = src_entry->object.vm_object; 1063 src_offset = src_entry->offset; 1064 1065 /* 1066 * Create the top-level object for the destination entry. (Doesn't 1067 * actually shadow anything - we copy the pages directly.) 1068 */ 1069 dst_object = vm_object_allocate(OBJT_DEFAULT, 1070 (vm_size_t) OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1071 1072 dst_entry->object.vm_object = dst_object; 1073 dst_entry->offset = 0; 1074 1075 prot = dst_entry->max_protection; 1076 1077 /* 1078 * Loop through all of the pages in the entry's range, copying each 1079 * one from the source object (it should be there) to the destination 1080 * object. 1081 */ 1082 for (vaddr = dst_entry->start, dst_offset = 0; 1083 vaddr < dst_entry->end; 1084 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) { 1085 1086 /* 1087 * Allocate a page in the destination object 1088 */ 1089 do { 1090 dst_m = vm_page_alloc(dst_object, 1091 OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL); 1092 if (dst_m == NULL) { 1093 VM_WAIT; 1094 } 1095 } while (dst_m == NULL); 1096 1097 /* 1098 * Find the page in the source object, and copy it in. 1099 * (Because the source is wired down, the page will be in 1100 * memory.) 1101 */ 1102 src_m = vm_page_lookup(src_object, 1103 OFF_TO_IDX(dst_offset + src_offset)); 1104 if (src_m == NULL) 1105 panic("vm_fault_copy_wired: page missing"); 1106 1107 vm_page_copy(src_m, dst_m); 1108 1109 /* 1110 * Enter it in the pmap... 1111 */ 1112 1113 vm_page_flag_clear(dst_m, PG_ZERO); 1114 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE); 1115 vm_page_flag_set(dst_m, PG_WRITEABLE|PG_MAPPED); 1116 1117 /* 1118 * Mark it no longer busy, and put it on the active list. 1119 */ 1120 vm_page_activate(dst_m); 1121 vm_page_wakeup(dst_m); 1122 } 1123 } 1124 1125 1126 /* 1127 * This routine checks around the requested page for other pages that 1128 * might be able to be faulted in. This routine brackets the viable 1129 * pages for the pages to be paged in. 1130 * 1131 * Inputs: 1132 * m, rbehind, rahead 1133 * 1134 * Outputs: 1135 * marray (array of vm_page_t), reqpage (index of requested page) 1136 * 1137 * Return value: 1138 * number of pages in marray 1139 * 1140 * This routine can't block. 1141 */ 1142 static int 1143 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1144 vm_page_t m; 1145 int rbehind; 1146 int rahead; 1147 vm_page_t *marray; 1148 int *reqpage; 1149 { 1150 int i,j; 1151 vm_object_t object; 1152 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1153 vm_page_t rtm; 1154 int cbehind, cahead; 1155 1156 GIANT_REQUIRED; 1157 1158 object = m->object; 1159 pindex = m->pindex; 1160 1161 /* 1162 * we don't fault-ahead for device pager 1163 */ 1164 if (object->type == OBJT_DEVICE) { 1165 *reqpage = 0; 1166 marray[0] = m; 1167 return 1; 1168 } 1169 1170 /* 1171 * if the requested page is not available, then give up now 1172 */ 1173 1174 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1175 return 0; 1176 } 1177 1178 if ((cbehind == 0) && (cahead == 0)) { 1179 *reqpage = 0; 1180 marray[0] = m; 1181 return 1; 1182 } 1183 1184 if (rahead > cahead) { 1185 rahead = cahead; 1186 } 1187 1188 if (rbehind > cbehind) { 1189 rbehind = cbehind; 1190 } 1191 1192 /* 1193 * try to do any readahead that we might have free pages for. 1194 */ 1195 if ((rahead + rbehind) > 1196 ((cnt.v_free_count + cnt.v_cache_count) - cnt.v_free_reserved)) { 1197 pagedaemon_wakeup(); 1198 marray[0] = m; 1199 *reqpage = 0; 1200 return 1; 1201 } 1202 1203 /* 1204 * scan backward for the read behind pages -- in memory 1205 */ 1206 if (pindex > 0) { 1207 if (rbehind > pindex) { 1208 rbehind = pindex; 1209 startpindex = 0; 1210 } else { 1211 startpindex = pindex - rbehind; 1212 } 1213 1214 for ( tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) { 1215 if (vm_page_lookup( object, tpindex)) { 1216 startpindex = tpindex + 1; 1217 break; 1218 } 1219 if (tpindex == 0) 1220 break; 1221 } 1222 1223 for(i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) { 1224 1225 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); 1226 if (rtm == NULL) { 1227 for (j = 0; j < i; j++) { 1228 vm_page_free(marray[j]); 1229 } 1230 marray[0] = m; 1231 *reqpage = 0; 1232 return 1; 1233 } 1234 1235 marray[i] = rtm; 1236 } 1237 } else { 1238 startpindex = 0; 1239 i = 0; 1240 } 1241 1242 marray[i] = m; 1243 /* page offset of the required page */ 1244 *reqpage = i; 1245 1246 tpindex = pindex + 1; 1247 i++; 1248 1249 /* 1250 * scan forward for the read ahead pages 1251 */ 1252 endpindex = tpindex + rahead; 1253 if (endpindex > object->size) 1254 endpindex = object->size; 1255 1256 for( ; tpindex < endpindex; i++, tpindex++) { 1257 1258 if (vm_page_lookup(object, tpindex)) { 1259 break; 1260 } 1261 1262 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); 1263 if (rtm == NULL) { 1264 break; 1265 } 1266 1267 marray[i] = rtm; 1268 } 1269 1270 /* return number of bytes of pages */ 1271 return i; 1272 } 1273