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