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 * vm_fault: 158 * 159 * Handle a page fault occuring at the given address, 160 * requiring the given permissions, in the map specified. 161 * If successful, the page is inserted into the 162 * associated physical map. 163 * 164 * NOTE: the given address should be truncated to the 165 * proper page address. 166 * 167 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 168 * a standard error specifying why the fault is fatal is returned. 169 * 170 * 171 * The map in question must be referenced, and remains so. 172 * Caller may hold no locks. 173 */ 174 int 175 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags) 176 { 177 vm_prot_t prot; 178 int result; 179 boolean_t wired; 180 int map_generation; 181 vm_object_t next_object; 182 vm_page_t marray[VM_FAULT_READ]; 183 int hardfault; 184 int faultcount; 185 struct faultstate fs; 186 187 cnt.v_vm_faults++; /* needs lock XXX */ 188 hardfault = 0; 189 190 RetryFault:; 191 fs.map = map; 192 193 /* 194 * Find the backing store object and offset into it to begin the 195 * search. 196 */ 197 if ((result = vm_map_lookup(&fs.map, vaddr, 198 fault_type, &fs.entry, &fs.first_object, 199 &fs.first_pindex, &prot, &wired)) != KERN_SUCCESS) { 200 if ((result != KERN_PROTECTION_FAILURE) || 201 ((fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE)) { 202 return result; 203 } 204 205 /* 206 * If we are user-wiring a r/w segment, and it is COW, then 207 * we need to do the COW operation. Note that we don't COW 208 * currently RO sections now, because it is NOT desirable 209 * to COW .text. We simply keep .text from ever being COW'ed 210 * and take the heat that one cannot debug wired .text sections. 211 */ 212 result = vm_map_lookup(&fs.map, vaddr, 213 VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE, 214 &fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired); 215 if (result != KERN_SUCCESS) { 216 return result; 217 } 218 219 /* 220 * If we don't COW now, on a user wire, the user will never 221 * be able to write to the mapping. If we don't make this 222 * restriction, the bookkeeping would be nearly impossible. 223 */ 224 if ((fs.entry->protection & VM_PROT_WRITE) == 0) 225 fs.entry->max_protection &= ~VM_PROT_WRITE; 226 } 227 228 map_generation = fs.map->timestamp; 229 230 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 231 panic("vm_fault: fault on nofault entry, addr: %lx", 232 (u_long)vaddr); 233 } 234 235 /* 236 * Make a reference to this object to prevent its disposal while we 237 * are messing with it. Once we have the reference, the map is free 238 * to be diddled. Since objects reference their shadows (and copies), 239 * they will stay around as well. 240 */ 241 vm_object_reference(fs.first_object); 242 vm_object_pip_add(fs.first_object, 1); 243 244 fs.vp = vnode_pager_lock(fs.first_object); 245 if ((fault_type & VM_PROT_WRITE) && 246 (fs.first_object->type == OBJT_VNODE)) { 247 vm_freeze_copyopts(fs.first_object, 248 fs.first_pindex, fs.first_pindex + 1); 249 } 250 251 fs.lookup_still_valid = TRUE; 252 253 if (wired) 254 fault_type = prot; 255 256 fs.first_m = NULL; 257 258 /* 259 * Search for the page at object/offset. 260 */ 261 262 fs.object = fs.first_object; 263 fs.pindex = fs.first_pindex; 264 265 while (TRUE) { 266 /* 267 * If the object is dead, we stop here 268 */ 269 270 if (fs.object->flags & OBJ_DEAD) { 271 unlock_and_deallocate(&fs); 272 return (KERN_PROTECTION_FAILURE); 273 } 274 275 /* 276 * See if page is resident 277 */ 278 279 fs.m = vm_page_lookup(fs.object, fs.pindex); 280 if (fs.m != NULL) { 281 int queue, s; 282 /* 283 * Wait/Retry if the page is busy. We have to do this 284 * if the page is busy via either PG_BUSY or 285 * vm_page_t->busy because the vm_pager may be using 286 * vm_page_t->busy for pageouts ( and even pageins if 287 * it is the vnode pager ), and we could end up trying 288 * to pagein and pageout the same page simultaniously. 289 * 290 * We can theoretically allow the busy case on a read 291 * fault if the page is marked valid, but since such 292 * pages are typically already pmap'd, putting that 293 * special case in might be more effort then it is 294 * worth. We cannot under any circumstances mess 295 * around with a vm_page_t->busy page except, perhaps, 296 * to pmap it. 297 */ 298 if ((fs.m->flags & PG_BUSY) || fs.m->busy) { 299 unlock_things(&fs); 300 (void)vm_page_sleep_busy(fs.m, TRUE, "vmpfw"); 301 cnt.v_intrans++; 302 vm_object_deallocate(fs.first_object); 303 goto RetryFault; 304 } 305 306 queue = fs.m->queue; 307 s = splvm(); 308 vm_page_unqueue_nowakeup(fs.m); 309 splx(s); 310 311 /* 312 * This code is designed to prevent thrashing in a 313 * low-memory situation by assuming that pages placed 314 * in the cache are generally inactive, so if a cached 315 * page is requested and we are low on memory, we try 316 * to wait for the low-memory condition to be resolved. 317 * 318 * This code cannot handle a major memory starvation 319 * situation where pages are forced into the cache and 320 * may cause 'good' programs to stall. As of 22Jan99 321 * the problem is still under discussion and not 322 * resolved. 323 */ 324 if (((queue - fs.m->pc) == PQ_CACHE) && 325 (cnt.v_free_count + cnt.v_cache_count) < cnt.v_free_min) { 326 vm_page_activate(fs.m); 327 unlock_and_deallocate(&fs); 328 VM_WAIT; 329 goto RetryFault; 330 } 331 332 /* 333 * Mark page busy for other processes, and the 334 * pagedaemon. If it still isn't completely valid 335 * (readable), jump to readrest, else break-out ( we 336 * found the page ). 337 */ 338 339 vm_page_busy(fs.m); 340 if (((fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) && 341 fs.m->object != kernel_object && fs.m->object != kmem_object) { 342 goto readrest; 343 } 344 345 break; 346 } 347 348 /* 349 * Page is not resident, If this is the search termination, 350 * allocate a new page. 351 */ 352 353 if (((fs.object->type != OBJT_DEFAULT) && 354 (((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired)) 355 || (fs.object == fs.first_object)) { 356 357 if (fs.pindex >= fs.object->size) { 358 unlock_and_deallocate(&fs); 359 return (KERN_PROTECTION_FAILURE); 360 } 361 362 /* 363 * Allocate a new page for this object/offset pair. 364 */ 365 fs.m = vm_page_alloc(fs.object, fs.pindex, 366 (fs.vp || fs.object->backing_object)? VM_ALLOC_NORMAL: VM_ALLOC_ZERO); 367 368 if (fs.m == NULL) { 369 unlock_and_deallocate(&fs); 370 VM_WAIT; 371 goto RetryFault; 372 } 373 } 374 375 readrest: 376 /* 377 * Have page, but it may not be entirely valid ( or valid at 378 * all ). If this object is not the default, try to fault-in 379 * the page as well as activate additional pages when 380 * appropriate, and page-in additional pages when appropriate. 381 */ 382 383 if (fs.object->type != OBJT_DEFAULT && 384 (((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired)) { 385 int rv; 386 int reqpage; 387 int ahead, behind; 388 u_char behavior = vm_map_entry_behavior(fs.entry); 389 390 if (behavior == MAP_ENTRY_BEHAV_RANDOM) { 391 ahead = 0; 392 behind = 0; 393 } else { 394 behind = (vaddr - fs.entry->start) >> PAGE_SHIFT; 395 if (behind > VM_FAULT_READ_BEHIND) 396 behind = VM_FAULT_READ_BEHIND; 397 398 ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1; 399 if (ahead > VM_FAULT_READ_AHEAD) 400 ahead = VM_FAULT_READ_AHEAD; 401 } 402 403 if ((fs.first_object->type != OBJT_DEVICE) && 404 (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL)) { 405 vm_pindex_t firstpindex, tmppindex; 406 if (fs.first_pindex < 407 2*(VM_FAULT_READ_BEHIND + VM_FAULT_READ_AHEAD + 1)) 408 firstpindex = 0; 409 else 410 firstpindex = fs.first_pindex - 411 2*(VM_FAULT_READ_BEHIND + VM_FAULT_READ_AHEAD + 1); 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 * Call the pager to retrieve the data, if any, after 464 * releasing the lock on the map. We hold a ref on 465 * fs.object and the pages are PG_BUSY'd. 466 */ 467 unlock_map(&fs); 468 469 rv = faultcount ? 470 vm_pager_get_pages(fs.object, marray, faultcount, 471 reqpage) : VM_PAGER_FAIL; 472 473 if (rv == VM_PAGER_OK) { 474 /* 475 * Found the page. Leave it busy while we play 476 * with it. 477 */ 478 479 /* 480 * Relookup in case pager changed page. Pager 481 * is responsible for disposition of old page 482 * if moved. 483 */ 484 fs.m = vm_page_lookup(fs.object, fs.pindex); 485 if(!fs.m) { 486 unlock_and_deallocate(&fs); 487 goto RetryFault; 488 } 489 490 hardfault++; 491 break; /* break to PAGE HAS BEEN FOUND */ 492 } 493 /* 494 * Remove the bogus page (which does not exist at this 495 * object/offset); before doing so, we must get back 496 * our object lock to preserve our invariant. 497 * 498 * Also wake up any other process that may want to bring 499 * in this page. 500 * 501 * If this is the top-level object, we must leave the 502 * busy page to prevent another process from rushing 503 * past us, and inserting the page in that object at 504 * the same time that we are. 505 */ 506 507 if (rv == VM_PAGER_ERROR) 508 printf("vm_fault: pager read error, pid %d (%s)\n", 509 curproc->p_pid, curproc->p_comm); 510 /* 511 * Data outside the range of the pager or an I/O error 512 */ 513 /* 514 * XXX - the check for kernel_map is a kludge to work 515 * around having the machine panic on a kernel space 516 * fault w/ I/O error. 517 */ 518 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 519 (rv == VM_PAGER_BAD)) { 520 vm_page_free(fs.m); 521 fs.m = NULL; 522 unlock_and_deallocate(&fs); 523 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 524 } 525 if (fs.object != fs.first_object) { 526 vm_page_free(fs.m); 527 fs.m = NULL; 528 /* 529 * XXX - we cannot just fall out at this 530 * point, m has been freed and is invalid! 531 */ 532 } 533 } 534 /* 535 * We get here if the object has default pager (or unwiring) 536 * or the pager doesn't have the page. 537 */ 538 if (fs.object == fs.first_object) 539 fs.first_m = fs.m; 540 541 /* 542 * Move on to the next object. Lock the next object before 543 * unlocking the current one. 544 */ 545 546 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 547 next_object = fs.object->backing_object; 548 if (next_object == NULL) { 549 /* 550 * If there's no object left, fill the page in the top 551 * object with zeros. 552 */ 553 if (fs.object != fs.first_object) { 554 vm_object_pip_wakeup(fs.object); 555 556 fs.object = fs.first_object; 557 fs.pindex = fs.first_pindex; 558 fs.m = fs.first_m; 559 } 560 fs.first_m = NULL; 561 562 /* 563 * Zero the page if necessary and mark it valid. 564 */ 565 if ((fs.m->flags & PG_ZERO) == 0) { 566 vm_page_zero_fill(fs.m); 567 } else { 568 cnt.v_ozfod++; 569 } 570 cnt.v_zfod++; 571 fs.m->valid = VM_PAGE_BITS_ALL; 572 break; /* break to PAGE HAS BEEN FOUND */ 573 } else { 574 if (fs.object != fs.first_object) { 575 vm_object_pip_wakeup(fs.object); 576 } 577 KASSERT(fs.object != next_object, ("object loop %p", next_object)); 578 fs.object = next_object; 579 vm_object_pip_add(fs.object, 1); 580 } 581 } 582 583 KASSERT((fs.m->flags & PG_BUSY) != 0, 584 ("vm_fault: not busy after main loop")); 585 586 /* 587 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 588 * is held.] 589 */ 590 591 /* 592 * If the page is being written, but isn't already owned by the 593 * top-level object, we have to copy it into a new page owned by the 594 * top-level object. 595 */ 596 597 if (fs.object != fs.first_object) { 598 /* 599 * We only really need to copy if we want to write it. 600 */ 601 602 if (fault_type & VM_PROT_WRITE) { 603 /* 604 * This allows pages to be virtually copied from a 605 * backing_object into the first_object, where the 606 * backing object has no other refs to it, and cannot 607 * gain any more refs. Instead of a bcopy, we just 608 * move the page from the backing object to the 609 * first object. Note that we must mark the page 610 * dirty in the first object so that it will go out 611 * to swap when needed. 612 */ 613 if (map_generation == fs.map->timestamp && 614 /* 615 * Only one shadow object 616 */ 617 (fs.object->shadow_count == 1) && 618 /* 619 * No COW refs, except us 620 */ 621 (fs.object->ref_count == 1) && 622 /* 623 * Noone else can look this object up 624 */ 625 (fs.object->handle == NULL) && 626 /* 627 * No other ways to look the object up 628 */ 629 ((fs.object->type == OBJT_DEFAULT) || 630 (fs.object->type == OBJT_SWAP)) && 631 /* 632 * We don't chase down the shadow chain 633 */ 634 (fs.object == fs.first_object->backing_object) && 635 636 /* 637 * grab the lock if we need to 638 */ 639 (fs.lookup_still_valid || 640 lockmgr(&fs.map->lock, LK_EXCLUSIVE|LK_NOWAIT, (void *)0, curproc) == 0) 641 ) { 642 643 fs.lookup_still_valid = 1; 644 /* 645 * get rid of the unnecessary page 646 */ 647 vm_page_protect(fs.first_m, VM_PROT_NONE); 648 vm_page_free(fs.first_m); 649 fs.first_m = NULL; 650 651 /* 652 * grab the page and put it into the 653 * process'es object. The page is 654 * automatically made dirty. 655 */ 656 vm_page_rename(fs.m, fs.first_object, fs.first_pindex); 657 fs.first_m = fs.m; 658 vm_page_busy(fs.first_m); 659 fs.m = NULL; 660 cnt.v_cow_optim++; 661 } else { 662 /* 663 * Oh, well, lets copy it. 664 */ 665 vm_page_copy(fs.m, fs.first_m); 666 } 667 668 if (fs.m) { 669 /* 670 * We no longer need the old page or object. 671 */ 672 release_page(&fs); 673 } 674 675 /* 676 * fs.object != fs.first_object due to above 677 * conditional 678 */ 679 680 vm_object_pip_wakeup(fs.object); 681 682 /* 683 * Only use the new page below... 684 */ 685 686 cnt.v_cow_faults++; 687 fs.m = fs.first_m; 688 fs.object = fs.first_object; 689 fs.pindex = fs.first_pindex; 690 691 } else { 692 prot &= ~VM_PROT_WRITE; 693 } 694 } 695 696 /* 697 * We must verify that the maps have not changed since our last 698 * lookup. 699 */ 700 701 if (!fs.lookup_still_valid && 702 (fs.map->timestamp != map_generation)) { 703 vm_object_t retry_object; 704 vm_pindex_t retry_pindex; 705 vm_prot_t retry_prot; 706 707 /* 708 * Since map entries may be pageable, make sure we can take a 709 * page fault on them. 710 */ 711 712 /* 713 * Unlock vnode before the lookup to avoid deadlock. E.G. 714 * avoid a deadlock between the inode and exec_map that can 715 * occur due to locks being obtained in different orders. 716 */ 717 718 if (fs.vp != NULL) { 719 vput(fs.vp); 720 fs.vp = NULL; 721 } 722 723 /* 724 * To avoid trying to write_lock the map while another process 725 * has it read_locked (in vm_map_pageable), we do not try for 726 * write permission. If the page is still writable, we will 727 * get write permission. If it is not, or has been marked 728 * needs_copy, we enter the mapping without write permission, 729 * and will merely take another fault. 730 */ 731 result = vm_map_lookup(&fs.map, vaddr, fault_type & ~VM_PROT_WRITE, 732 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 733 map_generation = fs.map->timestamp; 734 735 /* 736 * If we don't need the page any longer, put it on the active 737 * list (the easiest thing to do here). If no one needs it, 738 * pageout will grab it eventually. 739 */ 740 741 if (result != KERN_SUCCESS) { 742 release_page(&fs); 743 unlock_and_deallocate(&fs); 744 return (result); 745 } 746 fs.lookup_still_valid = TRUE; 747 748 if ((retry_object != fs.first_object) || 749 (retry_pindex != fs.first_pindex)) { 750 release_page(&fs); 751 unlock_and_deallocate(&fs); 752 goto RetryFault; 753 } 754 /* 755 * Check whether the protection has changed or the object has 756 * been copied while we left the map unlocked. Changing from 757 * read to write permission is OK - we leave the page 758 * write-protected, and catch the write fault. Changing from 759 * write to read permission means that we can't mark the page 760 * write-enabled after all. 761 */ 762 prot &= retry_prot; 763 } 764 765 /* 766 * Put this page into the physical map. We had to do the unlock above 767 * because pmap_enter may cause other faults. We don't put the page 768 * back on the active queue until later so that the page-out daemon 769 * won't find us (yet). 770 */ 771 772 if (prot & VM_PROT_WRITE) { 773 vm_page_flag_set(fs.m, PG_WRITEABLE); 774 vm_object_set_flag(fs.m->object, 775 OBJ_WRITEABLE|OBJ_MIGHTBEDIRTY); 776 /* 777 * If the fault is a write, we know that this page is being 778 * written NOW. This will save on the pmap_is_modified() calls 779 * later. 780 * 781 * Also tell the backing pager, if any, that it should remove 782 * any swap backing since the page is now dirty. 783 */ 784 if (fault_flags & VM_FAULT_DIRTY) { 785 vm_page_dirty(fs.m); 786 vm_pager_page_unswapped(fs.m); 787 } 788 } 789 790 /* 791 * Page had better still be busy 792 */ 793 794 KASSERT(fs.m->flags & PG_BUSY, 795 ("vm_fault: page %p not busy!", fs.m)); 796 797 unlock_things(&fs); 798 799 /* 800 * Sanity check: page must be completely valid or it is not fit to 801 * map into user space. vm_pager_get_pages() ensures this. 802 */ 803 804 if (fs.m->valid != VM_PAGE_BITS_ALL) { 805 vm_page_zero_invalid(fs.m, TRUE); 806 printf("Warning: page %p partially invalid on fault\n", fs.m); 807 } 808 809 pmap_enter(fs.map->pmap, vaddr, VM_PAGE_TO_PHYS(fs.m), prot, wired); 810 811 if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) { 812 pmap_prefault(fs.map->pmap, vaddr, fs.entry); 813 } 814 815 vm_page_flag_clear(fs.m, PG_ZERO); 816 vm_page_flag_set(fs.m, PG_MAPPED|PG_REFERENCED); 817 if (fault_flags & VM_FAULT_HOLD) 818 vm_page_hold(fs.m); 819 820 /* 821 * If the page is not wired down, then put it where the pageout daemon 822 * can find it. 823 */ 824 825 if (fault_flags & VM_FAULT_WIRE_MASK) { 826 if (wired) 827 vm_page_wire(fs.m); 828 else 829 vm_page_unwire(fs.m, 1); 830 } else { 831 vm_page_activate(fs.m); 832 } 833 834 if (curproc && (curproc->p_flag & P_INMEM) && curproc->p_stats) { 835 if (hardfault) { 836 curproc->p_stats->p_ru.ru_majflt++; 837 } else { 838 curproc->p_stats->p_ru.ru_minflt++; 839 } 840 } 841 842 /* 843 * Unlock everything, and return 844 */ 845 846 vm_page_wakeup(fs.m); 847 vm_object_deallocate(fs.first_object); 848 849 return (KERN_SUCCESS); 850 851 } 852 853 /* 854 * vm_fault_wire: 855 * 856 * Wire down a range of virtual addresses in a map. 857 */ 858 int 859 vm_fault_wire(map, start, end) 860 vm_map_t map; 861 vm_offset_t start, end; 862 { 863 864 register vm_offset_t va; 865 register pmap_t pmap; 866 int rv; 867 868 pmap = vm_map_pmap(map); 869 870 /* 871 * Inform the physical mapping system that the range of addresses may 872 * not fault, so that page tables and such can be locked down as well. 873 */ 874 875 pmap_pageable(pmap, start, end, FALSE); 876 877 /* 878 * We simulate a fault to get the page and enter it in the physical 879 * map. 880 */ 881 882 for (va = start; va < end; va += PAGE_SIZE) { 883 rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE, 884 VM_FAULT_CHANGE_WIRING); 885 if (rv) { 886 if (va != start) 887 vm_fault_unwire(map, start, va); 888 return (rv); 889 } 890 } 891 return (KERN_SUCCESS); 892 } 893 894 /* 895 * vm_fault_user_wire: 896 * 897 * Wire down a range of virtual addresses in a map. This 898 * is for user mode though, so we only ask for read access 899 * on currently read only sections. 900 */ 901 int 902 vm_fault_user_wire(map, start, end) 903 vm_map_t map; 904 vm_offset_t start, end; 905 { 906 907 register vm_offset_t va; 908 register pmap_t pmap; 909 int rv; 910 911 pmap = vm_map_pmap(map); 912 913 /* 914 * Inform the physical mapping system that the range of addresses may 915 * not fault, so that page tables and such can be locked down as well. 916 */ 917 918 pmap_pageable(pmap, start, end, FALSE); 919 920 /* 921 * We simulate a fault to get the page and enter it in the physical 922 * map. 923 */ 924 for (va = start; va < end; va += PAGE_SIZE) { 925 rv = vm_fault(map, va, VM_PROT_READ, VM_FAULT_USER_WIRE); 926 if (rv) { 927 if (va != start) 928 vm_fault_unwire(map, start, va); 929 return (rv); 930 } 931 } 932 return (KERN_SUCCESS); 933 } 934 935 936 /* 937 * vm_fault_unwire: 938 * 939 * Unwire a range of virtual addresses in a map. 940 */ 941 void 942 vm_fault_unwire(map, start, end) 943 vm_map_t map; 944 vm_offset_t start, end; 945 { 946 947 register vm_offset_t va, pa; 948 register pmap_t pmap; 949 950 pmap = vm_map_pmap(map); 951 952 /* 953 * Since the pages are wired down, we must be able to get their 954 * mappings from the physical map system. 955 */ 956 957 for (va = start; va < end; va += PAGE_SIZE) { 958 pa = pmap_extract(pmap, va); 959 if (pa != (vm_offset_t) 0) { 960 pmap_change_wiring(pmap, va, FALSE); 961 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1); 962 } 963 } 964 965 /* 966 * Inform the physical mapping system that the range of addresses may 967 * fault, so that page tables and such may be unwired themselves. 968 */ 969 970 pmap_pageable(pmap, start, end, TRUE); 971 972 } 973 974 /* 975 * Routine: 976 * vm_fault_copy_entry 977 * Function: 978 * Copy all of the pages from a wired-down map entry to another. 979 * 980 * In/out conditions: 981 * The source and destination maps must be locked for write. 982 * The source map entry must be wired down (or be a sharing map 983 * entry corresponding to a main map entry that is wired down). 984 */ 985 986 void 987 vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry) 988 vm_map_t dst_map; 989 vm_map_t src_map; 990 vm_map_entry_t dst_entry; 991 vm_map_entry_t src_entry; 992 { 993 vm_object_t dst_object; 994 vm_object_t src_object; 995 vm_ooffset_t dst_offset; 996 vm_ooffset_t src_offset; 997 vm_prot_t prot; 998 vm_offset_t vaddr; 999 vm_page_t dst_m; 1000 vm_page_t src_m; 1001 1002 #ifdef lint 1003 src_map++; 1004 #endif /* lint */ 1005 1006 src_object = src_entry->object.vm_object; 1007 src_offset = src_entry->offset; 1008 1009 /* 1010 * Create the top-level object for the destination entry. (Doesn't 1011 * actually shadow anything - we copy the pages directly.) 1012 */ 1013 dst_object = vm_object_allocate(OBJT_DEFAULT, 1014 (vm_size_t) OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1015 1016 dst_entry->object.vm_object = dst_object; 1017 dst_entry->offset = 0; 1018 1019 prot = dst_entry->max_protection; 1020 1021 /* 1022 * Loop through all of the pages in the entry's range, copying each 1023 * one from the source object (it should be there) to the destination 1024 * object. 1025 */ 1026 for (vaddr = dst_entry->start, dst_offset = 0; 1027 vaddr < dst_entry->end; 1028 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) { 1029 1030 /* 1031 * Allocate a page in the destination object 1032 */ 1033 do { 1034 dst_m = vm_page_alloc(dst_object, 1035 OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL); 1036 if (dst_m == NULL) { 1037 VM_WAIT; 1038 } 1039 } while (dst_m == NULL); 1040 1041 /* 1042 * Find the page in the source object, and copy it in. 1043 * (Because the source is wired down, the page will be in 1044 * memory.) 1045 */ 1046 src_m = vm_page_lookup(src_object, 1047 OFF_TO_IDX(dst_offset + src_offset)); 1048 if (src_m == NULL) 1049 panic("vm_fault_copy_wired: page missing"); 1050 1051 vm_page_copy(src_m, dst_m); 1052 1053 /* 1054 * Enter it in the pmap... 1055 */ 1056 1057 vm_page_flag_clear(dst_m, PG_ZERO); 1058 pmap_enter(dst_map->pmap, vaddr, VM_PAGE_TO_PHYS(dst_m), 1059 prot, FALSE); 1060 vm_page_flag_set(dst_m, PG_WRITEABLE|PG_MAPPED); 1061 1062 /* 1063 * Mark it no longer busy, and put it on the active list. 1064 */ 1065 vm_page_activate(dst_m); 1066 vm_page_wakeup(dst_m); 1067 } 1068 } 1069 1070 1071 /* 1072 * This routine checks around the requested page for other pages that 1073 * might be able to be faulted in. This routine brackets the viable 1074 * pages for the pages to be paged in. 1075 * 1076 * Inputs: 1077 * m, rbehind, rahead 1078 * 1079 * Outputs: 1080 * marray (array of vm_page_t), reqpage (index of requested page) 1081 * 1082 * Return value: 1083 * number of pages in marray 1084 */ 1085 static int 1086 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1087 vm_page_t m; 1088 int rbehind; 1089 int rahead; 1090 vm_page_t *marray; 1091 int *reqpage; 1092 { 1093 int i,j; 1094 vm_object_t object; 1095 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1096 vm_page_t rtm; 1097 int cbehind, cahead; 1098 1099 object = m->object; 1100 pindex = m->pindex; 1101 1102 /* 1103 * we don't fault-ahead for device pager 1104 */ 1105 if (object->type == OBJT_DEVICE) { 1106 *reqpage = 0; 1107 marray[0] = m; 1108 return 1; 1109 } 1110 1111 /* 1112 * if the requested page is not available, then give up now 1113 */ 1114 1115 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1116 return 0; 1117 } 1118 1119 if ((cbehind == 0) && (cahead == 0)) { 1120 *reqpage = 0; 1121 marray[0] = m; 1122 return 1; 1123 } 1124 1125 if (rahead > cahead) { 1126 rahead = cahead; 1127 } 1128 1129 if (rbehind > cbehind) { 1130 rbehind = cbehind; 1131 } 1132 1133 /* 1134 * try to do any readahead that we might have free pages for. 1135 */ 1136 if ((rahead + rbehind) > 1137 ((cnt.v_free_count + cnt.v_cache_count) - cnt.v_free_reserved)) { 1138 pagedaemon_wakeup(); 1139 marray[0] = m; 1140 *reqpage = 0; 1141 return 1; 1142 } 1143 1144 /* 1145 * scan backward for the read behind pages -- in memory 1146 */ 1147 if (pindex > 0) { 1148 if (rbehind > pindex) { 1149 rbehind = pindex; 1150 startpindex = 0; 1151 } else { 1152 startpindex = pindex - rbehind; 1153 } 1154 1155 for ( tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) { 1156 if (vm_page_lookup( object, tpindex)) { 1157 startpindex = tpindex + 1; 1158 break; 1159 } 1160 if (tpindex == 0) 1161 break; 1162 } 1163 1164 for(i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) { 1165 1166 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); 1167 if (rtm == NULL) { 1168 for (j = 0; j < i; j++) { 1169 vm_page_free(marray[j]); 1170 } 1171 marray[0] = m; 1172 *reqpage = 0; 1173 return 1; 1174 } 1175 1176 marray[i] = rtm; 1177 } 1178 } else { 1179 startpindex = 0; 1180 i = 0; 1181 } 1182 1183 marray[i] = m; 1184 /* page offset of the required page */ 1185 *reqpage = i; 1186 1187 tpindex = pindex + 1; 1188 i++; 1189 1190 /* 1191 * scan forward for the read ahead pages 1192 */ 1193 endpindex = tpindex + rahead; 1194 if (endpindex > object->size) 1195 endpindex = object->size; 1196 1197 for( ; tpindex < endpindex; i++, tpindex++) { 1198 1199 if (vm_page_lookup(object, tpindex)) { 1200 break; 1201 } 1202 1203 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); 1204 if (rtm == NULL) { 1205 break; 1206 } 1207 1208 marray[i] = rtm; 1209 } 1210 1211 /* return number of bytes of pages */ 1212 return i; 1213 } 1214