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