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/proc.h> 79 #include <sys/vnode.h> 80 #include <sys/resourcevar.h> 81 #include <sys/vmmeter.h> 82 83 #include <vm/vm.h> 84 #include <vm/vm_param.h> 85 #include <vm/vm_prot.h> 86 #include <sys/lock.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 occuring 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 simultaniously. 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)) || 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 * Noone 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 /* 731 * To avoid trying to write_lock the map while another process 732 * has it read_locked (in vm_map_pageable), we do not try for 733 * write permission. If the page is still writable, we will 734 * get write permission. If it is not, or has been marked 735 * needs_copy, we enter the mapping without write permission, 736 * and will merely take another fault. 737 */ 738 result = vm_map_lookup(&fs.map, vaddr, fault_type & ~VM_PROT_WRITE, 739 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 740 map_generation = fs.map->timestamp; 741 742 /* 743 * If we don't need the page any longer, put it on the active 744 * list (the easiest thing to do here). If no one needs it, 745 * pageout will grab it eventually. 746 */ 747 748 if (result != KERN_SUCCESS) { 749 release_page(&fs); 750 unlock_and_deallocate(&fs); 751 return (result); 752 } 753 fs.lookup_still_valid = TRUE; 754 755 if ((retry_object != fs.first_object) || 756 (retry_pindex != fs.first_pindex)) { 757 release_page(&fs); 758 unlock_and_deallocate(&fs); 759 goto RetryFault; 760 } 761 /* 762 * Check whether the protection has changed or the object has 763 * been copied while we left the map unlocked. Changing from 764 * read to write permission is OK - we leave the page 765 * write-protected, and catch the write fault. Changing from 766 * write to read permission means that we can't mark the page 767 * write-enabled after all. 768 */ 769 prot &= retry_prot; 770 } 771 772 /* 773 * Put this page into the physical map. We had to do the unlock above 774 * because pmap_enter may cause other faults. We don't put the page 775 * back on the active queue until later so that the page-out daemon 776 * won't find us (yet). 777 */ 778 779 if (prot & VM_PROT_WRITE) { 780 vm_page_flag_set(fs.m, PG_WRITEABLE); 781 vm_object_set_flag(fs.m->object, 782 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 783 /* 784 * If the fault is a write, we know that this page is being 785 * written NOW. This will save on the pmap_is_modified() calls 786 * later. 787 * 788 * Also tell the backing pager, if any, that it should remove 789 * any swap backing since the page is now dirty. 790 */ 791 if (fault_flags & VM_FAULT_DIRTY) { 792 vm_page_dirty(fs.m); 793 vm_pager_page_unswapped(fs.m); 794 } 795 } 796 797 /* 798 * Page had better still be busy 799 */ 800 801 KASSERT(fs.m->flags & PG_BUSY, 802 ("vm_fault: page %p not busy!", fs.m)); 803 804 unlock_things(&fs); 805 806 /* 807 * Sanity check: page must be completely valid or it is not fit to 808 * map into user space. vm_pager_get_pages() ensures this. 809 */ 810 811 if (fs.m->valid != VM_PAGE_BITS_ALL) { 812 vm_page_zero_invalid(fs.m, TRUE); 813 printf("Warning: page %p partially invalid on fault\n", fs.m); 814 } 815 816 pmap_enter(fs.map->pmap, vaddr, VM_PAGE_TO_PHYS(fs.m), prot, wired); 817 818 if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) { 819 pmap_prefault(fs.map->pmap, vaddr, fs.entry); 820 } 821 822 vm_page_flag_clear(fs.m, PG_ZERO); 823 vm_page_flag_set(fs.m, PG_MAPPED|PG_REFERENCED); 824 if (fault_flags & VM_FAULT_HOLD) 825 vm_page_hold(fs.m); 826 827 /* 828 * If the page is not wired down, then put it where the pageout daemon 829 * can find it. 830 */ 831 832 if (fault_flags & VM_FAULT_WIRE_MASK) { 833 if (wired) 834 vm_page_wire(fs.m); 835 else 836 vm_page_unwire(fs.m, 1); 837 } else { 838 vm_page_activate(fs.m); 839 } 840 841 if (curproc && (curproc->p_flag & P_INMEM) && curproc->p_stats) { 842 if (hardfault) { 843 curproc->p_stats->p_ru.ru_majflt++; 844 } else { 845 curproc->p_stats->p_ru.ru_minflt++; 846 } 847 } 848 849 /* 850 * Unlock everything, and return 851 */ 852 853 vm_page_wakeup(fs.m); 854 vm_object_deallocate(fs.first_object); 855 856 return (KERN_SUCCESS); 857 858 } 859 860 /* 861 * vm_fault_wire: 862 * 863 * Wire down a range of virtual addresses in a map. 864 */ 865 int 866 vm_fault_wire(map, start, end) 867 vm_map_t map; 868 vm_offset_t start, end; 869 { 870 871 register vm_offset_t va; 872 register pmap_t pmap; 873 int rv; 874 875 pmap = vm_map_pmap(map); 876 877 /* 878 * Inform the physical mapping system that the range of addresses may 879 * not fault, so that page tables and such can be locked down as well. 880 */ 881 882 pmap_pageable(pmap, start, end, FALSE); 883 884 /* 885 * We simulate a fault to get the page and enter it in the physical 886 * map. 887 */ 888 889 for (va = start; va < end; va += PAGE_SIZE) { 890 rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE, 891 VM_FAULT_CHANGE_WIRING); 892 if (rv) { 893 if (va != start) 894 vm_fault_unwire(map, start, va); 895 return (rv); 896 } 897 } 898 return (KERN_SUCCESS); 899 } 900 901 /* 902 * vm_fault_user_wire: 903 * 904 * Wire down a range of virtual addresses in a map. This 905 * is for user mode though, so we only ask for read access 906 * on currently read only sections. 907 */ 908 int 909 vm_fault_user_wire(map, start, end) 910 vm_map_t map; 911 vm_offset_t start, end; 912 { 913 914 register vm_offset_t va; 915 register pmap_t pmap; 916 int rv; 917 918 pmap = vm_map_pmap(map); 919 920 /* 921 * Inform the physical mapping system that the range of addresses may 922 * not fault, so that page tables and such can be locked down as well. 923 */ 924 925 pmap_pageable(pmap, start, end, FALSE); 926 927 /* 928 * We simulate a fault to get the page and enter it in the physical 929 * map. 930 */ 931 for (va = start; va < end; va += PAGE_SIZE) { 932 rv = vm_fault(map, va, VM_PROT_READ, VM_FAULT_USER_WIRE); 933 if (rv) { 934 if (va != start) 935 vm_fault_unwire(map, start, va); 936 return (rv); 937 } 938 } 939 return (KERN_SUCCESS); 940 } 941 942 943 /* 944 * vm_fault_unwire: 945 * 946 * Unwire a range of virtual addresses in a map. 947 */ 948 void 949 vm_fault_unwire(map, start, end) 950 vm_map_t map; 951 vm_offset_t start, end; 952 { 953 954 register vm_offset_t va, pa; 955 register pmap_t pmap; 956 957 pmap = vm_map_pmap(map); 958 959 /* 960 * Since the pages are wired down, we must be able to get their 961 * mappings from the physical map system. 962 */ 963 964 for (va = start; va < end; va += PAGE_SIZE) { 965 pa = pmap_extract(pmap, va); 966 if (pa != (vm_offset_t) 0) { 967 pmap_change_wiring(pmap, va, FALSE); 968 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1); 969 } 970 } 971 972 /* 973 * Inform the physical mapping system that the range of addresses may 974 * fault, so that page tables and such may be unwired themselves. 975 */ 976 977 pmap_pageable(pmap, start, end, TRUE); 978 979 } 980 981 /* 982 * Routine: 983 * vm_fault_copy_entry 984 * Function: 985 * Copy all of the pages from a wired-down map entry to another. 986 * 987 * In/out conditions: 988 * The source and destination maps must be locked for write. 989 * The source map entry must be wired down (or be a sharing map 990 * entry corresponding to a main map entry that is wired down). 991 */ 992 993 void 994 vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry) 995 vm_map_t dst_map; 996 vm_map_t src_map; 997 vm_map_entry_t dst_entry; 998 vm_map_entry_t src_entry; 999 { 1000 vm_object_t dst_object; 1001 vm_object_t src_object; 1002 vm_ooffset_t dst_offset; 1003 vm_ooffset_t src_offset; 1004 vm_prot_t prot; 1005 vm_offset_t vaddr; 1006 vm_page_t dst_m; 1007 vm_page_t src_m; 1008 1009 #ifdef lint 1010 src_map++; 1011 #endif /* lint */ 1012 1013 src_object = src_entry->object.vm_object; 1014 src_offset = src_entry->offset; 1015 1016 /* 1017 * Create the top-level object for the destination entry. (Doesn't 1018 * actually shadow anything - we copy the pages directly.) 1019 */ 1020 dst_object = vm_object_allocate(OBJT_DEFAULT, 1021 (vm_size_t) OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1022 1023 dst_entry->object.vm_object = dst_object; 1024 dst_entry->offset = 0; 1025 1026 prot = dst_entry->max_protection; 1027 1028 /* 1029 * Loop through all of the pages in the entry's range, copying each 1030 * one from the source object (it should be there) to the destination 1031 * object. 1032 */ 1033 for (vaddr = dst_entry->start, dst_offset = 0; 1034 vaddr < dst_entry->end; 1035 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) { 1036 1037 /* 1038 * Allocate a page in the destination object 1039 */ 1040 do { 1041 dst_m = vm_page_alloc(dst_object, 1042 OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL); 1043 if (dst_m == NULL) { 1044 VM_WAIT; 1045 } 1046 } while (dst_m == NULL); 1047 1048 /* 1049 * Find the page in the source object, and copy it in. 1050 * (Because the source is wired down, the page will be in 1051 * memory.) 1052 */ 1053 src_m = vm_page_lookup(src_object, 1054 OFF_TO_IDX(dst_offset + src_offset)); 1055 if (src_m == NULL) 1056 panic("vm_fault_copy_wired: page missing"); 1057 1058 vm_page_copy(src_m, dst_m); 1059 1060 /* 1061 * Enter it in the pmap... 1062 */ 1063 1064 vm_page_flag_clear(dst_m, PG_ZERO); 1065 pmap_enter(dst_map->pmap, vaddr, VM_PAGE_TO_PHYS(dst_m), 1066 prot, FALSE); 1067 vm_page_flag_set(dst_m, PG_WRITEABLE|PG_MAPPED); 1068 1069 /* 1070 * Mark it no longer busy, and put it on the active list. 1071 */ 1072 vm_page_activate(dst_m); 1073 vm_page_wakeup(dst_m); 1074 } 1075 } 1076 1077 1078 /* 1079 * This routine checks around the requested page for other pages that 1080 * might be able to be faulted in. This routine brackets the viable 1081 * pages for the pages to be paged in. 1082 * 1083 * Inputs: 1084 * m, rbehind, rahead 1085 * 1086 * Outputs: 1087 * marray (array of vm_page_t), reqpage (index of requested page) 1088 * 1089 * Return value: 1090 * number of pages in marray 1091 */ 1092 static int 1093 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1094 vm_page_t m; 1095 int rbehind; 1096 int rahead; 1097 vm_page_t *marray; 1098 int *reqpage; 1099 { 1100 int i,j; 1101 vm_object_t object; 1102 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1103 vm_page_t rtm; 1104 int cbehind, cahead; 1105 1106 object = m->object; 1107 pindex = m->pindex; 1108 1109 /* 1110 * we don't fault-ahead for device pager 1111 */ 1112 if (object->type == OBJT_DEVICE) { 1113 *reqpage = 0; 1114 marray[0] = m; 1115 return 1; 1116 } 1117 1118 /* 1119 * if the requested page is not available, then give up now 1120 */ 1121 1122 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1123 return 0; 1124 } 1125 1126 if ((cbehind == 0) && (cahead == 0)) { 1127 *reqpage = 0; 1128 marray[0] = m; 1129 return 1; 1130 } 1131 1132 if (rahead > cahead) { 1133 rahead = cahead; 1134 } 1135 1136 if (rbehind > cbehind) { 1137 rbehind = cbehind; 1138 } 1139 1140 /* 1141 * try to do any readahead that we might have free pages for. 1142 */ 1143 if ((rahead + rbehind) > 1144 ((cnt.v_free_count + cnt.v_cache_count) - cnt.v_free_reserved)) { 1145 pagedaemon_wakeup(); 1146 marray[0] = m; 1147 *reqpage = 0; 1148 return 1; 1149 } 1150 1151 /* 1152 * scan backward for the read behind pages -- in memory 1153 */ 1154 if (pindex > 0) { 1155 if (rbehind > pindex) { 1156 rbehind = pindex; 1157 startpindex = 0; 1158 } else { 1159 startpindex = pindex - rbehind; 1160 } 1161 1162 for ( tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) { 1163 if (vm_page_lookup( object, tpindex)) { 1164 startpindex = tpindex + 1; 1165 break; 1166 } 1167 if (tpindex == 0) 1168 break; 1169 } 1170 1171 for(i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) { 1172 1173 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); 1174 if (rtm == NULL) { 1175 for (j = 0; j < i; j++) { 1176 vm_page_free(marray[j]); 1177 } 1178 marray[0] = m; 1179 *reqpage = 0; 1180 return 1; 1181 } 1182 1183 marray[i] = rtm; 1184 } 1185 } else { 1186 startpindex = 0; 1187 i = 0; 1188 } 1189 1190 marray[i] = m; 1191 /* page offset of the required page */ 1192 *reqpage = i; 1193 1194 tpindex = pindex + 1; 1195 i++; 1196 1197 /* 1198 * scan forward for the read ahead pages 1199 */ 1200 endpindex = tpindex + rahead; 1201 if (endpindex > object->size) 1202 endpindex = object->size; 1203 1204 for( ; tpindex < endpindex; i++, tpindex++) { 1205 1206 if (vm_page_lookup(object, tpindex)) { 1207 break; 1208 } 1209 1210 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); 1211 if (rtm == NULL) { 1212 break; 1213 } 1214 1215 marray[i] = rtm; 1216 } 1217 1218 /* return number of bytes of pages */ 1219 return i; 1220 } 1221