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