1 /* 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * 9 * 10 * This code is derived from software contributed to Berkeley by 11 * The Mach Operating System project at Carnegie-Mellon University. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 * 41 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94 42 * 43 * 44 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 45 * All rights reserved. 46 * 47 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 48 * 49 * Permission to use, copy, modify and distribute this software and 50 * its documentation is hereby granted, provided that both the copyright 51 * notice and this permission notice appear in all copies of the 52 * software, derivative works or modified versions, and any portions 53 * thereof, and that both notices appear in supporting documentation. 54 * 55 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 56 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 57 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 58 * 59 * Carnegie Mellon requests users of this software to return to 60 * 61 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 62 * School of Computer Science 63 * Carnegie Mellon University 64 * Pittsburgh PA 15213-3890 65 * 66 * any improvements or extensions that they make and grant Carnegie the 67 * rights to redistribute these changes. 68 * 69 * $FreeBSD$ 70 */ 71 72 /* 73 * Page fault handling module. 74 */ 75 #include <sys/param.h> 76 #include <sys/systm.h> 77 #include <sys/kernel.h> 78 #include <sys/lock.h> 79 #include <sys/mutex.h> 80 #include <sys/proc.h> 81 #include <sys/resourcevar.h> 82 #include <sys/sysctl.h> 83 #include <sys/vmmeter.h> 84 #include <sys/vnode.h> 85 86 #include <vm/vm.h> 87 #include <vm/vm_param.h> 88 #include <vm/pmap.h> 89 #include <vm/vm_map.h> 90 #include <vm/vm_object.h> 91 #include <vm/vm_page.h> 92 #include <vm/vm_pageout.h> 93 #include <vm/vm_kern.h> 94 #include <vm/vm_pager.h> 95 #include <vm/vnode_pager.h> 96 #include <vm/vm_extern.h> 97 98 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); 99 100 #define VM_FAULT_READ_AHEAD 8 101 #define VM_FAULT_READ_BEHIND 7 102 #define VM_FAULT_READ (VM_FAULT_READ_AHEAD+VM_FAULT_READ_BEHIND+1) 103 104 struct faultstate { 105 vm_page_t m; 106 vm_object_t object; 107 vm_pindex_t pindex; 108 vm_page_t first_m; 109 vm_object_t first_object; 110 vm_pindex_t first_pindex; 111 vm_map_t map; 112 vm_map_entry_t entry; 113 int lookup_still_valid; 114 struct vnode *vp; 115 }; 116 117 static __inline void 118 release_page(struct faultstate *fs) 119 { 120 vm_page_lock_queues(); 121 vm_page_wakeup(fs->m); 122 vm_page_deactivate(fs->m); 123 vm_page_unlock_queues(); 124 fs->m = NULL; 125 } 126 127 static __inline void 128 unlock_map(struct faultstate *fs) 129 { 130 if (fs->lookup_still_valid) { 131 vm_map_lookup_done(fs->map, fs->entry); 132 fs->lookup_still_valid = FALSE; 133 } 134 } 135 136 static void 137 _unlock_things(struct faultstate *fs, int dealloc) 138 { 139 GIANT_REQUIRED; 140 vm_object_pip_wakeup(fs->object); 141 if (fs->object != fs->first_object) { 142 vm_page_lock_queues(); 143 vm_page_free(fs->first_m); 144 vm_page_unlock_queues(); 145 vm_object_pip_wakeup(fs->first_object); 146 fs->first_m = NULL; 147 } 148 if (dealloc) { 149 vm_object_deallocate(fs->first_object); 150 } 151 unlock_map(fs); 152 if (fs->vp != NULL) { 153 vput(fs->vp); 154 fs->vp = NULL; 155 } 156 } 157 158 #define unlock_things(fs) _unlock_things(fs, 0) 159 #define unlock_and_deallocate(fs) _unlock_things(fs, 1) 160 161 /* 162 * TRYPAGER - used by vm_fault to calculate whether the pager for the 163 * current object *might* contain the page. 164 * 165 * default objects are zero-fill, there is no real pager. 166 */ 167 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 168 (((fault_flags & VM_FAULT_WIRE_MASK) == 0) || wired)) 169 170 /* 171 * vm_fault: 172 * 173 * Handle a page fault occurring at the given address, 174 * requiring the given permissions, in the map specified. 175 * If successful, the page is inserted into the 176 * associated physical map. 177 * 178 * NOTE: the given address should be truncated to the 179 * proper page address. 180 * 181 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 182 * a standard error specifying why the fault is fatal is returned. 183 * 184 * 185 * The map in question must be referenced, and remains so. 186 * Caller may hold no locks. 187 */ 188 int 189 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 190 int fault_flags) 191 { 192 vm_prot_t prot; 193 int result; 194 boolean_t growstack, wired; 195 int map_generation; 196 vm_object_t next_object; 197 vm_page_t marray[VM_FAULT_READ]; 198 int hardfault; 199 int faultcount; 200 struct faultstate fs; 201 202 hardfault = 0; 203 growstack = TRUE; 204 atomic_add_int(&cnt.v_vm_faults, 1); 205 206 mtx_lock(&Giant); 207 RetryFault:; 208 209 /* 210 * Find the backing store object and offset into it to begin the 211 * search. 212 */ 213 fs.map = map; 214 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 215 &fs.first_object, &fs.first_pindex, &prot, &wired); 216 if (result != KERN_SUCCESS) { 217 if (result != KERN_PROTECTION_FAILURE || 218 (fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE) { 219 if (growstack && result == KERN_INVALID_ADDRESS && 220 map != kernel_map && curproc != NULL) { 221 result = vm_map_growstack(curproc, vaddr); 222 if (result != KERN_SUCCESS) { 223 mtx_unlock(&Giant); 224 return (KERN_FAILURE); 225 } 226 growstack = FALSE; 227 goto RetryFault; 228 } 229 mtx_unlock(&Giant); 230 return (result); 231 } 232 233 /* 234 * If we are user-wiring a r/w segment, and it is COW, then 235 * we need to do the COW operation. Note that we don't COW 236 * currently RO sections now, because it is NOT desirable 237 * to COW .text. We simply keep .text from ever being COW'ed 238 * and take the heat that one cannot debug wired .text sections. 239 */ 240 result = vm_map_lookup(&fs.map, vaddr, 241 VM_PROT_READ|VM_PROT_WRITE|VM_PROT_OVERRIDE_WRITE, 242 &fs.entry, &fs.first_object, &fs.first_pindex, &prot, &wired); 243 if (result != KERN_SUCCESS) { 244 mtx_unlock(&Giant); 245 return (result); 246 } 247 248 /* 249 * If we don't COW now, on a user wire, the user will never 250 * be able to write to the mapping. If we don't make this 251 * restriction, the bookkeeping would be nearly impossible. 252 * 253 * XXX The following assignment modifies the map without 254 * holding a write lock on it. 255 */ 256 if ((fs.entry->protection & VM_PROT_WRITE) == 0) 257 fs.entry->max_protection &= ~VM_PROT_WRITE; 258 } 259 260 map_generation = fs.map->timestamp; 261 262 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 263 panic("vm_fault: fault on nofault entry, addr: %lx", 264 (u_long)vaddr); 265 } 266 267 /* 268 * Make a reference to this object to prevent its disposal while we 269 * are messing with it. Once we have the reference, the map is free 270 * to be diddled. Since objects reference their shadows (and copies), 271 * they will stay around as well. 272 * 273 * Bump the paging-in-progress count to prevent size changes (e.g. 274 * truncation operations) during I/O. This must be done after 275 * obtaining the vnode lock in order to avoid possible deadlocks. 276 * 277 * XXX vnode_pager_lock() can block without releasing the map lock. 278 */ 279 vm_object_reference(fs.first_object); 280 fs.vp = vnode_pager_lock(fs.first_object); 281 vm_object_pip_add(fs.first_object, 1); 282 283 fs.lookup_still_valid = TRUE; 284 285 if (wired) 286 fault_type = prot; 287 288 fs.first_m = NULL; 289 290 /* 291 * Search for the page at object/offset. 292 */ 293 fs.object = fs.first_object; 294 fs.pindex = fs.first_pindex; 295 while (TRUE) { 296 /* 297 * If the object is dead, we stop here 298 */ 299 if (fs.object->flags & OBJ_DEAD) { 300 unlock_and_deallocate(&fs); 301 mtx_unlock(&Giant); 302 return (KERN_PROTECTION_FAILURE); 303 } 304 305 /* 306 * See if page is resident 307 */ 308 fs.m = vm_page_lookup(fs.object, fs.pindex); 309 if (fs.m != NULL) { 310 int queue, s; 311 312 /* 313 * check for page-based copy on write 314 */ 315 vm_page_lock_queues(); 316 if ((fs.m->cow) && 317 (fault_type & VM_PROT_WRITE)) { 318 s = splvm(); 319 vm_page_cowfault(fs.m); 320 splx(s); 321 vm_page_unlock_queues(); 322 unlock_things(&fs); 323 goto RetryFault; 324 } 325 326 /* 327 * Wait/Retry if the page is busy. We have to do this 328 * if the page is busy via either PG_BUSY or 329 * vm_page_t->busy because the vm_pager may be using 330 * vm_page_t->busy for pageouts ( and even pageins if 331 * it is the vnode pager ), and we could end up trying 332 * to pagein and pageout the same page simultaneously. 333 * 334 * We can theoretically allow the busy case on a read 335 * fault if the page is marked valid, but since such 336 * pages are typically already pmap'd, putting that 337 * special case in might be more effort then it is 338 * worth. We cannot under any circumstances mess 339 * around with a vm_page_t->busy page except, perhaps, 340 * to pmap it. 341 */ 342 if ((fs.m->flags & PG_BUSY) || fs.m->busy) { 343 vm_page_unlock_queues(); 344 unlock_things(&fs); 345 vm_page_lock_queues(); 346 if (!vm_page_sleep_if_busy(fs.m, TRUE, "vmpfw")) 347 vm_page_unlock_queues(); 348 cnt.v_intrans++; 349 vm_object_deallocate(fs.first_object); 350 goto RetryFault; 351 } 352 queue = fs.m->queue; 353 354 s = splvm(); 355 vm_pageq_remove_nowakeup(fs.m); 356 splx(s); 357 358 if ((queue - fs.m->pc) == PQ_CACHE && vm_page_count_severe()) { 359 vm_page_activate(fs.m); 360 vm_page_unlock_queues(); 361 unlock_and_deallocate(&fs); 362 VM_WAITPFAULT; 363 goto RetryFault; 364 } 365 366 /* 367 * Mark page busy for other processes, and the 368 * pagedaemon. If it still isn't completely valid 369 * (readable), jump to readrest, else break-out ( we 370 * found the page ). 371 */ 372 vm_page_busy(fs.m); 373 vm_page_unlock_queues(); 374 if (((fs.m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) && 375 fs.m->object != kernel_object && fs.m->object != kmem_object) { 376 goto readrest; 377 } 378 379 break; 380 } 381 382 /* 383 * Page is not resident, If this is the search termination 384 * or the pager might contain the page, allocate a new page. 385 */ 386 if (TRYPAGER || fs.object == fs.first_object) { 387 if (fs.pindex >= fs.object->size) { 388 unlock_and_deallocate(&fs); 389 mtx_unlock(&Giant); 390 return (KERN_PROTECTION_FAILURE); 391 } 392 393 /* 394 * Allocate a new page for this object/offset pair. 395 */ 396 fs.m = NULL; 397 if (!vm_page_count_severe()) { 398 fs.m = vm_page_alloc(fs.object, fs.pindex, 399 (fs.vp || fs.object->backing_object)? VM_ALLOC_NORMAL: VM_ALLOC_ZERO); 400 } 401 if (fs.m == NULL) { 402 unlock_and_deallocate(&fs); 403 VM_WAITPFAULT; 404 goto RetryFault; 405 } 406 } 407 408 readrest: 409 /* 410 * We have found a valid page or we have allocated a new page. 411 * The page thus may not be valid or may not be entirely 412 * valid. 413 * 414 * Attempt to fault-in the page if there is a chance that the 415 * pager has it, and potentially fault in additional pages 416 * at the same time. 417 */ 418 if (TRYPAGER) { 419 int rv; 420 int reqpage; 421 int ahead, behind; 422 u_char behavior = vm_map_entry_behavior(fs.entry); 423 424 if (behavior == MAP_ENTRY_BEHAV_RANDOM) { 425 ahead = 0; 426 behind = 0; 427 } else { 428 behind = (vaddr - fs.entry->start) >> PAGE_SHIFT; 429 if (behind > VM_FAULT_READ_BEHIND) 430 behind = VM_FAULT_READ_BEHIND; 431 432 ahead = ((fs.entry->end - vaddr) >> PAGE_SHIFT) - 1; 433 if (ahead > VM_FAULT_READ_AHEAD) 434 ahead = VM_FAULT_READ_AHEAD; 435 } 436 437 if ((fs.first_object->type != OBJT_DEVICE) && 438 (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL || 439 (behavior != MAP_ENTRY_BEHAV_RANDOM && 440 fs.pindex >= fs.entry->lastr && 441 fs.pindex < fs.entry->lastr + VM_FAULT_READ)) 442 ) { 443 vm_pindex_t firstpindex, tmppindex; 444 445 if (fs.first_pindex < 2 * VM_FAULT_READ) 446 firstpindex = 0; 447 else 448 firstpindex = fs.first_pindex - 2 * VM_FAULT_READ; 449 450 vm_page_lock_queues(); 451 /* 452 * note: partially valid pages cannot be 453 * included in the lookahead - NFS piecemeal 454 * writes will barf on it badly. 455 */ 456 for (tmppindex = fs.first_pindex - 1; 457 tmppindex >= firstpindex; 458 --tmppindex) { 459 vm_page_t mt; 460 461 mt = vm_page_lookup(fs.first_object, tmppindex); 462 if (mt == NULL || (mt->valid != VM_PAGE_BITS_ALL)) 463 break; 464 if (mt->busy || 465 (mt->flags & (PG_BUSY | PG_FICTITIOUS | PG_UNMANAGED)) || 466 mt->hold_count || 467 mt->wire_count) 468 continue; 469 if (mt->dirty == 0) 470 vm_page_test_dirty(mt); 471 if (mt->dirty) { 472 pmap_remove_all(mt); 473 vm_page_deactivate(mt); 474 } else { 475 vm_page_cache(mt); 476 } 477 } 478 vm_page_unlock_queues(); 479 ahead += behind; 480 behind = 0; 481 } 482 483 /* 484 * now we find out if any other pages should be paged 485 * in at this time this routine checks to see if the 486 * pages surrounding this fault reside in the same 487 * object as the page for this fault. If they do, 488 * then they are faulted in also into the object. The 489 * array "marray" returned contains an array of 490 * vm_page_t structs where one of them is the 491 * vm_page_t passed to the routine. The reqpage 492 * return value is the index into the marray for the 493 * vm_page_t passed to the routine. 494 * 495 * fs.m plus the additional pages are PG_BUSY'd. 496 * 497 * XXX vm_fault_additional_pages() can block 498 * without releasing the map lock. 499 */ 500 faultcount = vm_fault_additional_pages( 501 fs.m, behind, ahead, marray, &reqpage); 502 503 /* 504 * update lastr imperfectly (we do not know how much 505 * getpages will actually read), but good enough. 506 * 507 * XXX The following assignment modifies the map 508 * without holding a write lock on it. 509 */ 510 fs.entry->lastr = fs.pindex + faultcount - behind; 511 512 /* 513 * Call the pager to retrieve the data, if any, after 514 * releasing the lock on the map. We hold a ref on 515 * fs.object and the pages are PG_BUSY'd. 516 */ 517 unlock_map(&fs); 518 519 rv = faultcount ? 520 vm_pager_get_pages(fs.object, marray, faultcount, 521 reqpage) : VM_PAGER_FAIL; 522 523 if (rv == VM_PAGER_OK) { 524 /* 525 * Found the page. Leave it busy while we play 526 * with it. 527 */ 528 529 /* 530 * Relookup in case pager changed page. Pager 531 * is responsible for disposition of old page 532 * if moved. 533 */ 534 fs.m = vm_page_lookup(fs.object, fs.pindex); 535 if (!fs.m) { 536 unlock_and_deallocate(&fs); 537 goto RetryFault; 538 } 539 540 hardfault++; 541 break; /* break to PAGE HAS BEEN FOUND */ 542 } 543 /* 544 * Remove the bogus page (which does not exist at this 545 * object/offset); before doing so, we must get back 546 * our object lock to preserve our invariant. 547 * 548 * Also wake up any other process that may want to bring 549 * in this page. 550 * 551 * If this is the top-level object, we must leave the 552 * busy page to prevent another process from rushing 553 * past us, and inserting the page in that object at 554 * the same time that we are. 555 */ 556 if (rv == VM_PAGER_ERROR) 557 printf("vm_fault: pager read error, pid %d (%s)\n", 558 curproc->p_pid, curproc->p_comm); 559 /* 560 * Data outside the range of the pager or an I/O error 561 */ 562 /* 563 * XXX - the check for kernel_map is a kludge to work 564 * around having the machine panic on a kernel space 565 * fault w/ I/O error. 566 */ 567 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 568 (rv == VM_PAGER_BAD)) { 569 vm_page_lock_queues(); 570 vm_page_free(fs.m); 571 vm_page_unlock_queues(); 572 fs.m = NULL; 573 unlock_and_deallocate(&fs); 574 mtx_unlock(&Giant); 575 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 576 } 577 if (fs.object != fs.first_object) { 578 vm_page_lock_queues(); 579 vm_page_free(fs.m); 580 vm_page_unlock_queues(); 581 fs.m = NULL; 582 /* 583 * XXX - we cannot just fall out at this 584 * point, m has been freed and is invalid! 585 */ 586 } 587 } 588 589 /* 590 * We get here if the object has default pager (or unwiring) 591 * or the pager doesn't have the page. 592 */ 593 if (fs.object == fs.first_object) 594 fs.first_m = fs.m; 595 596 /* 597 * Move on to the next object. Lock the next object before 598 * unlocking the current one. 599 */ 600 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 601 next_object = fs.object->backing_object; 602 if (next_object == NULL) { 603 /* 604 * If there's no object left, fill the page in the top 605 * object with zeros. 606 */ 607 if (fs.object != fs.first_object) { 608 vm_object_pip_wakeup(fs.object); 609 610 fs.object = fs.first_object; 611 fs.pindex = fs.first_pindex; 612 fs.m = fs.first_m; 613 } 614 fs.first_m = NULL; 615 616 /* 617 * Zero the page if necessary and mark it valid. 618 */ 619 if ((fs.m->flags & PG_ZERO) == 0) { 620 pmap_zero_page(fs.m); 621 } else { 622 cnt.v_ozfod++; 623 } 624 cnt.v_zfod++; 625 fs.m->valid = VM_PAGE_BITS_ALL; 626 break; /* break to PAGE HAS BEEN FOUND */ 627 } else { 628 if (fs.object != fs.first_object) { 629 vm_object_pip_wakeup(fs.object); 630 } 631 KASSERT(fs.object != next_object, ("object loop %p", next_object)); 632 fs.object = next_object; 633 vm_object_pip_add(fs.object, 1); 634 } 635 } 636 637 KASSERT((fs.m->flags & PG_BUSY) != 0, 638 ("vm_fault: not busy after main loop")); 639 640 /* 641 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 642 * is held.] 643 */ 644 645 /* 646 * If the page is being written, but isn't already owned by the 647 * top-level object, we have to copy it into a new page owned by the 648 * top-level object. 649 */ 650 if (fs.object != fs.first_object) { 651 /* 652 * We only really need to copy if we want to write it. 653 */ 654 if (fault_type & VM_PROT_WRITE) { 655 /* 656 * This allows pages to be virtually copied from a 657 * backing_object into the first_object, where the 658 * backing object has no other refs to it, and cannot 659 * gain any more refs. Instead of a bcopy, we just 660 * move the page from the backing object to the 661 * first object. Note that we must mark the page 662 * dirty in the first object so that it will go out 663 * to swap when needed. 664 */ 665 if (map_generation == fs.map->timestamp && 666 /* 667 * Only one shadow object 668 */ 669 (fs.object->shadow_count == 1) && 670 /* 671 * No COW refs, except us 672 */ 673 (fs.object->ref_count == 1) && 674 /* 675 * No one else can look this object up 676 */ 677 (fs.object->handle == NULL) && 678 /* 679 * No other ways to look the object up 680 */ 681 ((fs.object->type == OBJT_DEFAULT) || 682 (fs.object->type == OBJT_SWAP)) && 683 /* 684 * We don't chase down the shadow chain 685 */ 686 (fs.object == fs.first_object->backing_object) && 687 688 /* 689 * grab the lock if we need to 690 */ 691 (fs.lookup_still_valid || vm_map_trylock(fs.map))) { 692 693 fs.lookup_still_valid = 1; 694 /* 695 * get rid of the unnecessary page 696 */ 697 vm_page_lock_queues(); 698 pmap_remove_all(fs.first_m); 699 vm_page_free(fs.first_m); 700 fs.first_m = NULL; 701 702 /* 703 * grab the page and put it into the 704 * process'es object. The page is 705 * automatically made dirty. 706 */ 707 vm_page_rename(fs.m, fs.first_object, fs.first_pindex); 708 fs.first_m = fs.m; 709 vm_page_busy(fs.first_m); 710 vm_page_unlock_queues(); 711 fs.m = NULL; 712 cnt.v_cow_optim++; 713 } else { 714 /* 715 * Oh, well, lets copy it. 716 */ 717 vm_page_copy(fs.m, fs.first_m); 718 } 719 720 if (fs.m) { 721 /* 722 * We no longer need the old page or object. 723 */ 724 release_page(&fs); 725 } 726 727 /* 728 * fs.object != fs.first_object due to above 729 * conditional 730 */ 731 vm_object_pip_wakeup(fs.object); 732 733 /* 734 * Only use the new page below... 735 */ 736 cnt.v_cow_faults++; 737 fs.m = fs.first_m; 738 fs.object = fs.first_object; 739 fs.pindex = fs.first_pindex; 740 741 } else { 742 prot &= ~VM_PROT_WRITE; 743 } 744 } 745 746 /* 747 * We must verify that the maps have not changed since our last 748 * lookup. 749 */ 750 if (!fs.lookup_still_valid && 751 (fs.map->timestamp != map_generation)) { 752 vm_object_t retry_object; 753 vm_pindex_t retry_pindex; 754 vm_prot_t retry_prot; 755 756 /* 757 * Since map entries may be pageable, make sure we can take a 758 * page fault on them. 759 */ 760 761 /* 762 * Unlock vnode before the lookup to avoid deadlock. E.G. 763 * avoid a deadlock between the inode and exec_map that can 764 * occur due to locks being obtained in different orders. 765 */ 766 if (fs.vp != NULL) { 767 vput(fs.vp); 768 fs.vp = NULL; 769 } 770 771 if (fs.map->infork) { 772 release_page(&fs); 773 unlock_and_deallocate(&fs); 774 goto RetryFault; 775 } 776 777 /* 778 * To avoid trying to write_lock the map while another process 779 * has it read_locked (in vm_map_pageable), we do not try for 780 * write permission. If the page is still writable, we will 781 * get write permission. If it is not, or has been marked 782 * needs_copy, we enter the mapping without write permission, 783 * and will merely take another fault. 784 */ 785 result = vm_map_lookup(&fs.map, vaddr, fault_type & ~VM_PROT_WRITE, 786 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 787 map_generation = fs.map->timestamp; 788 789 /* 790 * If we don't need the page any longer, put it on the active 791 * list (the easiest thing to do here). If no one needs it, 792 * pageout will grab it eventually. 793 */ 794 if (result != KERN_SUCCESS) { 795 release_page(&fs); 796 unlock_and_deallocate(&fs); 797 mtx_unlock(&Giant); 798 return (result); 799 } 800 fs.lookup_still_valid = TRUE; 801 802 if ((retry_object != fs.first_object) || 803 (retry_pindex != fs.first_pindex)) { 804 release_page(&fs); 805 unlock_and_deallocate(&fs); 806 goto RetryFault; 807 } 808 /* 809 * Check whether the protection has changed or the object has 810 * been copied while we left the map unlocked. Changing from 811 * read to write permission is OK - we leave the page 812 * write-protected, and catch the write fault. Changing from 813 * write to read permission means that we can't mark the page 814 * write-enabled after all. 815 */ 816 prot &= retry_prot; 817 } 818 819 /* 820 * Put this page into the physical map. We had to do the unlock above 821 * because pmap_enter may cause other faults. We don't put the page 822 * back on the active queue until later so that the page-out daemon 823 * won't find us (yet). 824 */ 825 826 if (prot & VM_PROT_WRITE) { 827 vm_page_lock_queues(); 828 vm_page_flag_set(fs.m, PG_WRITEABLE); 829 vm_object_set_writeable_dirty(fs.m->object); 830 831 /* 832 * If the fault is a write, we know that this page is being 833 * written NOW so dirty it explicitly to save on 834 * pmap_is_modified() calls later. 835 * 836 * If this is a NOSYNC mmap we do not want to set PG_NOSYNC 837 * if the page is already dirty to prevent data written with 838 * the expectation of being synced from not being synced. 839 * Likewise if this entry does not request NOSYNC then make 840 * sure the page isn't marked NOSYNC. Applications sharing 841 * data should use the same flags to avoid ping ponging. 842 * 843 * Also tell the backing pager, if any, that it should remove 844 * any swap backing since the page is now dirty. 845 */ 846 if (fs.entry->eflags & MAP_ENTRY_NOSYNC) { 847 if (fs.m->dirty == 0) 848 vm_page_flag_set(fs.m, PG_NOSYNC); 849 } else { 850 vm_page_flag_clear(fs.m, PG_NOSYNC); 851 } 852 vm_page_unlock_queues(); 853 if (fault_flags & VM_FAULT_DIRTY) { 854 int s; 855 vm_page_dirty(fs.m); 856 s = splvm(); 857 vm_pager_page_unswapped(fs.m); 858 splx(s); 859 } 860 } 861 862 /* 863 * Page had better still be busy 864 */ 865 KASSERT(fs.m->flags & PG_BUSY, 866 ("vm_fault: page %p not busy!", fs.m)); 867 unlock_things(&fs); 868 869 /* 870 * Sanity check: page must be completely valid or it is not fit to 871 * map into user space. vm_pager_get_pages() ensures this. 872 */ 873 if (fs.m->valid != VM_PAGE_BITS_ALL) { 874 vm_page_zero_invalid(fs.m, TRUE); 875 printf("Warning: page %p partially invalid on fault\n", fs.m); 876 } 877 pmap_enter(fs.map->pmap, vaddr, fs.m, prot, wired); 878 if (((fault_flags & VM_FAULT_WIRE_MASK) == 0) && (wired == 0)) { 879 pmap_prefault(fs.map->pmap, vaddr, fs.entry); 880 } 881 vm_page_lock_queues(); 882 vm_page_flag_clear(fs.m, PG_ZERO); 883 vm_page_flag_set(fs.m, PG_REFERENCED); 884 885 /* 886 * If the page is not wired down, then put it where the pageout daemon 887 * can find it. 888 */ 889 if (fault_flags & VM_FAULT_WIRE_MASK) { 890 if (wired) 891 vm_page_wire(fs.m); 892 else 893 vm_page_unwire(fs.m, 1); 894 } else { 895 vm_page_activate(fs.m); 896 } 897 vm_page_wakeup(fs.m); 898 vm_page_unlock_queues(); 899 mtx_lock_spin(&sched_lock); 900 if (curproc && (curproc->p_sflag & PS_INMEM) && curproc->p_stats) { 901 if (hardfault) { 902 curproc->p_stats->p_ru.ru_majflt++; 903 } else { 904 curproc->p_stats->p_ru.ru_minflt++; 905 } 906 } 907 mtx_unlock_spin(&sched_lock); 908 909 /* 910 * Unlock everything, and return 911 */ 912 vm_object_deallocate(fs.first_object); 913 mtx_unlock(&Giant); 914 return (KERN_SUCCESS); 915 } 916 917 /* 918 * vm_fault_quick: 919 * 920 * Ensure that the requested virtual address, which may be in userland, 921 * is valid. Fault-in the page if necessary. Return -1 on failure. 922 */ 923 int 924 vm_fault_quick(caddr_t v, int prot) 925 { 926 int r; 927 928 if (prot & VM_PROT_WRITE) 929 r = subyte(v, fubyte(v)); 930 else 931 r = fubyte(v); 932 return(r); 933 } 934 935 /* 936 * vm_fault_wire: 937 * 938 * Wire down a range of virtual addresses in a map. 939 */ 940 int 941 vm_fault_wire(map, start, end, user_wire) 942 vm_map_t map; 943 vm_offset_t start, end; 944 boolean_t user_wire; 945 { 946 vm_offset_t va; 947 int rv; 948 949 /* 950 * We simulate a fault to get the page and enter it in the physical 951 * map. For user wiring, we only ask for read access on currently 952 * read-only sections. 953 */ 954 for (va = start; va < end; va += PAGE_SIZE) { 955 rv = vm_fault(map, va, 956 user_wire ? VM_PROT_READ : VM_PROT_READ | VM_PROT_WRITE, 957 user_wire ? VM_FAULT_USER_WIRE : VM_FAULT_CHANGE_WIRING); 958 if (rv) { 959 if (va != start) 960 vm_fault_unwire(map, start, va); 961 return (rv); 962 } 963 } 964 return (KERN_SUCCESS); 965 } 966 967 /* 968 * vm_fault_unwire: 969 * 970 * Unwire a range of virtual addresses in a map. 971 */ 972 void 973 vm_fault_unwire(map, start, end) 974 vm_map_t map; 975 vm_offset_t start, end; 976 { 977 vm_offset_t va, pa; 978 pmap_t pmap; 979 980 pmap = vm_map_pmap(map); 981 982 mtx_lock(&Giant); 983 /* 984 * Since the pages are wired down, we must be able to get their 985 * mappings from the physical map system. 986 */ 987 for (va = start; va < end; va += PAGE_SIZE) { 988 pa = pmap_extract(pmap, va); 989 if (pa != (vm_offset_t) 0) { 990 pmap_change_wiring(pmap, va, FALSE); 991 vm_page_lock_queues(); 992 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1); 993 vm_page_unlock_queues(); 994 } 995 } 996 mtx_unlock(&Giant); 997 } 998 999 /* 1000 * Routine: 1001 * vm_fault_copy_entry 1002 * Function: 1003 * Copy all of the pages from a wired-down map entry to another. 1004 * 1005 * In/out conditions: 1006 * The source and destination maps must be locked for write. 1007 * The source map entry must be wired down (or be a sharing map 1008 * entry corresponding to a main map entry that is wired down). 1009 */ 1010 void 1011 vm_fault_copy_entry(dst_map, src_map, dst_entry, src_entry) 1012 vm_map_t dst_map; 1013 vm_map_t src_map; 1014 vm_map_entry_t dst_entry; 1015 vm_map_entry_t src_entry; 1016 { 1017 vm_object_t dst_object; 1018 vm_object_t src_object; 1019 vm_ooffset_t dst_offset; 1020 vm_ooffset_t src_offset; 1021 vm_prot_t prot; 1022 vm_offset_t vaddr; 1023 vm_page_t dst_m; 1024 vm_page_t src_m; 1025 1026 #ifdef lint 1027 src_map++; 1028 #endif /* lint */ 1029 1030 src_object = src_entry->object.vm_object; 1031 src_offset = src_entry->offset; 1032 1033 /* 1034 * Create the top-level object for the destination entry. (Doesn't 1035 * actually shadow anything - we copy the pages directly.) 1036 */ 1037 dst_object = vm_object_allocate(OBJT_DEFAULT, 1038 (vm_size_t) OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1039 1040 dst_entry->object.vm_object = dst_object; 1041 dst_entry->offset = 0; 1042 1043 prot = dst_entry->max_protection; 1044 1045 /* 1046 * Loop through all of the pages in the entry's range, copying each 1047 * one from the source object (it should be there) to the destination 1048 * object. 1049 */ 1050 for (vaddr = dst_entry->start, dst_offset = 0; 1051 vaddr < dst_entry->end; 1052 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) { 1053 1054 /* 1055 * Allocate a page in the destination object 1056 */ 1057 do { 1058 dst_m = vm_page_alloc(dst_object, 1059 OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL); 1060 if (dst_m == NULL) { 1061 VM_WAIT; 1062 } 1063 } while (dst_m == NULL); 1064 1065 /* 1066 * Find the page in the source object, and copy it in. 1067 * (Because the source is wired down, the page will be in 1068 * memory.) 1069 */ 1070 src_m = vm_page_lookup(src_object, 1071 OFF_TO_IDX(dst_offset + src_offset)); 1072 if (src_m == NULL) 1073 panic("vm_fault_copy_wired: page missing"); 1074 1075 vm_page_copy(src_m, dst_m); 1076 1077 /* 1078 * Enter it in the pmap... 1079 */ 1080 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE); 1081 vm_page_lock_queues(); 1082 vm_page_flag_set(dst_m, PG_WRITEABLE); 1083 1084 /* 1085 * Mark it no longer busy, and put it on the active list. 1086 */ 1087 vm_page_activate(dst_m); 1088 vm_page_wakeup(dst_m); 1089 vm_page_unlock_queues(); 1090 } 1091 } 1092 1093 1094 /* 1095 * This routine checks around the requested page for other pages that 1096 * might be able to be faulted in. This routine brackets the viable 1097 * pages for the pages to be paged in. 1098 * 1099 * Inputs: 1100 * m, rbehind, rahead 1101 * 1102 * Outputs: 1103 * marray (array of vm_page_t), reqpage (index of requested page) 1104 * 1105 * Return value: 1106 * number of pages in marray 1107 * 1108 * This routine can't block. 1109 */ 1110 static int 1111 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1112 vm_page_t m; 1113 int rbehind; 1114 int rahead; 1115 vm_page_t *marray; 1116 int *reqpage; 1117 { 1118 int i,j; 1119 vm_object_t object; 1120 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1121 vm_page_t rtm; 1122 int cbehind, cahead; 1123 1124 GIANT_REQUIRED; 1125 1126 object = m->object; 1127 pindex = m->pindex; 1128 1129 /* 1130 * we don't fault-ahead for device pager 1131 */ 1132 if (object->type == OBJT_DEVICE) { 1133 *reqpage = 0; 1134 marray[0] = m; 1135 return 1; 1136 } 1137 1138 /* 1139 * if the requested page is not available, then give up now 1140 */ 1141 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1142 return 0; 1143 } 1144 1145 if ((cbehind == 0) && (cahead == 0)) { 1146 *reqpage = 0; 1147 marray[0] = m; 1148 return 1; 1149 } 1150 1151 if (rahead > cahead) { 1152 rahead = cahead; 1153 } 1154 1155 if (rbehind > cbehind) { 1156 rbehind = cbehind; 1157 } 1158 1159 /* 1160 * try to do any readahead that we might have free pages for. 1161 */ 1162 if ((rahead + rbehind) > 1163 ((cnt.v_free_count + cnt.v_cache_count) - cnt.v_free_reserved)) { 1164 pagedaemon_wakeup(); 1165 marray[0] = m; 1166 *reqpage = 0; 1167 return 1; 1168 } 1169 1170 /* 1171 * scan backward for the read behind pages -- in memory 1172 */ 1173 if (pindex > 0) { 1174 if (rbehind > pindex) { 1175 rbehind = pindex; 1176 startpindex = 0; 1177 } else { 1178 startpindex = pindex - rbehind; 1179 } 1180 1181 for (tpindex = pindex - 1; tpindex >= startpindex; tpindex -= 1) { 1182 if (vm_page_lookup(object, tpindex)) { 1183 startpindex = tpindex + 1; 1184 break; 1185 } 1186 if (tpindex == 0) 1187 break; 1188 } 1189 1190 for (i = 0, tpindex = startpindex; tpindex < pindex; i++, tpindex++) { 1191 1192 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); 1193 if (rtm == NULL) { 1194 vm_page_lock_queues(); 1195 for (j = 0; j < i; j++) { 1196 vm_page_free(marray[j]); 1197 } 1198 vm_page_unlock_queues(); 1199 marray[0] = m; 1200 *reqpage = 0; 1201 return 1; 1202 } 1203 1204 marray[i] = rtm; 1205 } 1206 } else { 1207 startpindex = 0; 1208 i = 0; 1209 } 1210 1211 marray[i] = m; 1212 /* page offset of the required page */ 1213 *reqpage = i; 1214 1215 tpindex = pindex + 1; 1216 i++; 1217 1218 /* 1219 * scan forward for the read ahead pages 1220 */ 1221 endpindex = tpindex + rahead; 1222 if (endpindex > object->size) 1223 endpindex = object->size; 1224 1225 for (; tpindex < endpindex; i++, tpindex++) { 1226 1227 if (vm_page_lookup(object, tpindex)) { 1228 break; 1229 } 1230 1231 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL); 1232 if (rtm == NULL) { 1233 break; 1234 } 1235 1236 marray[i] = rtm; 1237 } 1238 1239 /* return number of bytes of pages */ 1240 return i; 1241 } 1242