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 70 /* 71 * Page fault handling module. 72 */ 73 74 #include <sys/cdefs.h> 75 __FBSDID("$FreeBSD$"); 76 77 #include "opt_ktrace.h" 78 #include "opt_vm.h" 79 80 #include <sys/param.h> 81 #include <sys/systm.h> 82 #include <sys/kernel.h> 83 #include <sys/lock.h> 84 #include <sys/proc.h> 85 #include <sys/resourcevar.h> 86 #include <sys/rwlock.h> 87 #include <sys/sysctl.h> 88 #include <sys/vmmeter.h> 89 #include <sys/vnode.h> 90 #ifdef KTRACE 91 #include <sys/ktrace.h> 92 #endif 93 94 #include <vm/vm.h> 95 #include <vm/vm_param.h> 96 #include <vm/pmap.h> 97 #include <vm/vm_map.h> 98 #include <vm/vm_object.h> 99 #include <vm/vm_page.h> 100 #include <vm/vm_pageout.h> 101 #include <vm/vm_kern.h> 102 #include <vm/vm_pager.h> 103 #include <vm/vm_extern.h> 104 105 #define PFBAK 4 106 #define PFFOR 4 107 108 static int vm_fault_additional_pages(vm_page_t, int, int, vm_page_t *, int *); 109 110 #define VM_FAULT_READ_BEHIND 8 111 #define VM_FAULT_READ_DEFAULT (1 + VM_FAULT_READ_AHEAD_INIT) 112 #define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX) 113 #define VM_FAULT_NINCR (VM_FAULT_READ_MAX / VM_FAULT_READ_BEHIND) 114 #define VM_FAULT_SUM (VM_FAULT_NINCR * (VM_FAULT_NINCR + 1) / 2) 115 #define VM_FAULT_CACHE_BEHIND (VM_FAULT_READ_BEHIND * VM_FAULT_SUM) 116 117 struct faultstate { 118 vm_page_t m; 119 vm_object_t object; 120 vm_pindex_t pindex; 121 vm_page_t first_m; 122 vm_object_t first_object; 123 vm_pindex_t first_pindex; 124 vm_map_t map; 125 vm_map_entry_t entry; 126 int lookup_still_valid; 127 struct vnode *vp; 128 }; 129 130 static void vm_fault_cache_behind(const struct faultstate *fs, int distance); 131 static void vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra, 132 int faultcount, int reqpage); 133 134 static inline void 135 release_page(struct faultstate *fs) 136 { 137 138 vm_page_xunbusy(fs->m); 139 vm_page_lock(fs->m); 140 vm_page_deactivate(fs->m); 141 vm_page_unlock(fs->m); 142 fs->m = NULL; 143 } 144 145 static inline void 146 unlock_map(struct faultstate *fs) 147 { 148 149 if (fs->lookup_still_valid) { 150 vm_map_lookup_done(fs->map, fs->entry); 151 fs->lookup_still_valid = FALSE; 152 } 153 } 154 155 static void 156 unlock_and_deallocate(struct faultstate *fs) 157 { 158 159 vm_object_pip_wakeup(fs->object); 160 VM_OBJECT_WUNLOCK(fs->object); 161 if (fs->object != fs->first_object) { 162 VM_OBJECT_WLOCK(fs->first_object); 163 vm_page_lock(fs->first_m); 164 vm_page_free(fs->first_m); 165 vm_page_unlock(fs->first_m); 166 vm_object_pip_wakeup(fs->first_object); 167 VM_OBJECT_WUNLOCK(fs->first_object); 168 fs->first_m = NULL; 169 } 170 vm_object_deallocate(fs->first_object); 171 unlock_map(fs); 172 if (fs->vp != NULL) { 173 vput(fs->vp); 174 fs->vp = NULL; 175 } 176 } 177 178 static void 179 vm_fault_dirty(vm_map_entry_t entry, vm_page_t m, vm_prot_t prot, 180 vm_prot_t fault_type, int fault_flags, boolean_t set_wd) 181 { 182 boolean_t need_dirty; 183 184 if (((prot & VM_PROT_WRITE) == 0 && 185 (fault_flags & VM_FAULT_DIRTY) == 0) || 186 (m->oflags & VPO_UNMANAGED) != 0) 187 return; 188 189 VM_OBJECT_ASSERT_LOCKED(m->object); 190 191 need_dirty = ((fault_type & VM_PROT_WRITE) != 0 && 192 (fault_flags & VM_FAULT_CHANGE_WIRING) == 0) || 193 (fault_flags & VM_FAULT_DIRTY) != 0; 194 195 if (set_wd) 196 vm_object_set_writeable_dirty(m->object); 197 else 198 /* 199 * If two callers of vm_fault_dirty() with set_wd == 200 * FALSE, one for the map entry with MAP_ENTRY_NOSYNC 201 * flag set, other with flag clear, race, it is 202 * possible for the no-NOSYNC thread to see m->dirty 203 * != 0 and not clear VPO_NOSYNC. Take vm_page lock 204 * around manipulation of VPO_NOSYNC and 205 * vm_page_dirty() call, to avoid the race and keep 206 * m->oflags consistent. 207 */ 208 vm_page_lock(m); 209 210 /* 211 * If this is a NOSYNC mmap we do not want to set VPO_NOSYNC 212 * if the page is already dirty to prevent data written with 213 * the expectation of being synced from not being synced. 214 * Likewise if this entry does not request NOSYNC then make 215 * sure the page isn't marked NOSYNC. Applications sharing 216 * data should use the same flags to avoid ping ponging. 217 */ 218 if ((entry->eflags & MAP_ENTRY_NOSYNC) != 0) { 219 if (m->dirty == 0) { 220 m->oflags |= VPO_NOSYNC; 221 } 222 } else { 223 m->oflags &= ~VPO_NOSYNC; 224 } 225 226 /* 227 * If the fault is a write, we know that this page is being 228 * written NOW so dirty it explicitly to save on 229 * pmap_is_modified() calls later. 230 * 231 * Also tell the backing pager, if any, that it should remove 232 * any swap backing since the page is now dirty. 233 */ 234 if (need_dirty) 235 vm_page_dirty(m); 236 if (!set_wd) 237 vm_page_unlock(m); 238 if (need_dirty) 239 vm_pager_page_unswapped(m); 240 } 241 242 /* 243 * TRYPAGER - used by vm_fault to calculate whether the pager for the 244 * current object *might* contain the page. 245 * 246 * default objects are zero-fill, there is no real pager. 247 */ 248 #define TRYPAGER (fs.object->type != OBJT_DEFAULT && \ 249 ((fault_flags & VM_FAULT_CHANGE_WIRING) == 0 || wired)) 250 251 /* 252 * vm_fault: 253 * 254 * Handle a page fault occurring at the given address, 255 * requiring the given permissions, in the map specified. 256 * If successful, the page is inserted into the 257 * associated physical map. 258 * 259 * NOTE: the given address should be truncated to the 260 * proper page address. 261 * 262 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 263 * a standard error specifying why the fault is fatal is returned. 264 * 265 * The map in question must be referenced, and remains so. 266 * Caller may hold no locks. 267 */ 268 int 269 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 270 int fault_flags) 271 { 272 struct thread *td; 273 int result; 274 275 td = curthread; 276 if ((td->td_pflags & TDP_NOFAULTING) != 0) 277 return (KERN_PROTECTION_FAILURE); 278 #ifdef KTRACE 279 if (map != kernel_map && KTRPOINT(td, KTR_FAULT)) 280 ktrfault(vaddr, fault_type); 281 #endif 282 result = vm_fault_hold(map, trunc_page(vaddr), fault_type, fault_flags, 283 NULL); 284 #ifdef KTRACE 285 if (map != kernel_map && KTRPOINT(td, KTR_FAULTEND)) 286 ktrfaultend(result); 287 #endif 288 return (result); 289 } 290 291 int 292 vm_fault_hold(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 293 int fault_flags, vm_page_t *m_hold) 294 { 295 vm_prot_t prot; 296 int alloc_req, era, faultcount, nera, reqpage, result; 297 boolean_t growstack, is_first_object_locked, wired; 298 int map_generation; 299 vm_object_t next_object; 300 vm_page_t marray[VM_FAULT_READ_MAX]; 301 int hardfault; 302 struct faultstate fs; 303 struct vnode *vp; 304 vm_page_t m; 305 int ahead, behind, cluster_offset, error, locked; 306 307 hardfault = 0; 308 growstack = TRUE; 309 PCPU_INC(cnt.v_vm_faults); 310 fs.vp = NULL; 311 faultcount = reqpage = 0; 312 313 RetryFault:; 314 315 /* 316 * Find the backing store object and offset into it to begin the 317 * search. 318 */ 319 fs.map = map; 320 result = vm_map_lookup(&fs.map, vaddr, fault_type, &fs.entry, 321 &fs.first_object, &fs.first_pindex, &prot, &wired); 322 if (result != KERN_SUCCESS) { 323 if (growstack && result == KERN_INVALID_ADDRESS && 324 map != kernel_map) { 325 result = vm_map_growstack(curproc, vaddr); 326 if (result != KERN_SUCCESS) 327 return (KERN_FAILURE); 328 growstack = FALSE; 329 goto RetryFault; 330 } 331 return (result); 332 } 333 334 map_generation = fs.map->timestamp; 335 336 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 337 panic("vm_fault: fault on nofault entry, addr: %lx", 338 (u_long)vaddr); 339 } 340 341 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION && 342 fs.entry->wiring_thread != curthread) { 343 vm_map_unlock_read(fs.map); 344 vm_map_lock(fs.map); 345 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) && 346 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) { 347 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP; 348 vm_map_unlock_and_wait(fs.map, 0); 349 } else 350 vm_map_unlock(fs.map); 351 goto RetryFault; 352 } 353 354 if (wired) 355 fault_type = prot | (fault_type & VM_PROT_COPY); 356 357 if (fs.vp == NULL /* avoid locked vnode leak */ && 358 (fault_flags & (VM_FAULT_CHANGE_WIRING | VM_FAULT_DIRTY)) == 0 && 359 /* avoid calling vm_object_set_writeable_dirty() */ 360 ((prot & VM_PROT_WRITE) == 0 || 361 (fs.first_object->type != OBJT_VNODE && 362 (fs.first_object->flags & OBJ_TMPFS_NODE) == 0) || 363 (fs.first_object->flags & OBJ_MIGHTBEDIRTY) != 0)) { 364 VM_OBJECT_RLOCK(fs.first_object); 365 if ((prot & VM_PROT_WRITE) != 0 && 366 (fs.first_object->type == OBJT_VNODE || 367 (fs.first_object->flags & OBJ_TMPFS_NODE) != 0) && 368 (fs.first_object->flags & OBJ_MIGHTBEDIRTY) == 0) 369 goto fast_failed; 370 m = vm_page_lookup(fs.first_object, fs.first_pindex); 371 /* A busy page can be mapped for read|execute access. */ 372 if (m == NULL || ((prot & VM_PROT_WRITE) != 0 && 373 vm_page_busied(m)) || m->valid != VM_PAGE_BITS_ALL) 374 goto fast_failed; 375 result = pmap_enter(fs.map->pmap, vaddr, m, prot, 376 fault_type | PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED : 377 0), 0); 378 if (result != KERN_SUCCESS) 379 goto fast_failed; 380 if (m_hold != NULL) { 381 *m_hold = m; 382 vm_page_lock(m); 383 vm_page_hold(m); 384 vm_page_unlock(m); 385 } 386 vm_fault_dirty(fs.entry, m, prot, fault_type, fault_flags, 387 FALSE); 388 VM_OBJECT_RUNLOCK(fs.first_object); 389 if (!wired) 390 vm_fault_prefault(&fs, vaddr, 0, 0); 391 vm_map_lookup_done(fs.map, fs.entry); 392 curthread->td_ru.ru_minflt++; 393 return (KERN_SUCCESS); 394 fast_failed: 395 if (!VM_OBJECT_TRYUPGRADE(fs.first_object)) { 396 VM_OBJECT_RUNLOCK(fs.first_object); 397 VM_OBJECT_WLOCK(fs.first_object); 398 } 399 } else { 400 VM_OBJECT_WLOCK(fs.first_object); 401 } 402 403 /* 404 * Make a reference to this object to prevent its disposal while we 405 * are messing with it. Once we have the reference, the map is free 406 * to be diddled. Since objects reference their shadows (and copies), 407 * they will stay around as well. 408 * 409 * Bump the paging-in-progress count to prevent size changes (e.g. 410 * truncation operations) during I/O. This must be done after 411 * obtaining the vnode lock in order to avoid possible deadlocks. 412 */ 413 vm_object_reference_locked(fs.first_object); 414 vm_object_pip_add(fs.first_object, 1); 415 416 fs.lookup_still_valid = TRUE; 417 418 fs.first_m = NULL; 419 420 /* 421 * Search for the page at object/offset. 422 */ 423 fs.object = fs.first_object; 424 fs.pindex = fs.first_pindex; 425 while (TRUE) { 426 /* 427 * If the object is dead, we stop here 428 */ 429 if (fs.object->flags & OBJ_DEAD) { 430 unlock_and_deallocate(&fs); 431 return (KERN_PROTECTION_FAILURE); 432 } 433 434 /* 435 * See if page is resident 436 */ 437 fs.m = vm_page_lookup(fs.object, fs.pindex); 438 if (fs.m != NULL) { 439 /* 440 * Wait/Retry if the page is busy. We have to do this 441 * if the page is either exclusive or shared busy 442 * because the vm_pager may be using read busy for 443 * pageouts (and even pageins if it is the vnode 444 * pager), and we could end up trying to pagein and 445 * pageout the same page simultaneously. 446 * 447 * We can theoretically allow the busy case on a read 448 * fault if the page is marked valid, but since such 449 * pages are typically already pmap'd, putting that 450 * special case in might be more effort then it is 451 * worth. We cannot under any circumstances mess 452 * around with a shared busied page except, perhaps, 453 * to pmap it. 454 */ 455 if (vm_page_busied(fs.m)) { 456 /* 457 * Reference the page before unlocking and 458 * sleeping so that the page daemon is less 459 * likely to reclaim it. 460 */ 461 vm_page_aflag_set(fs.m, PGA_REFERENCED); 462 if (fs.object != fs.first_object) { 463 if (!VM_OBJECT_TRYWLOCK( 464 fs.first_object)) { 465 VM_OBJECT_WUNLOCK(fs.object); 466 VM_OBJECT_WLOCK(fs.first_object); 467 VM_OBJECT_WLOCK(fs.object); 468 } 469 vm_page_lock(fs.first_m); 470 vm_page_free(fs.first_m); 471 vm_page_unlock(fs.first_m); 472 vm_object_pip_wakeup(fs.first_object); 473 VM_OBJECT_WUNLOCK(fs.first_object); 474 fs.first_m = NULL; 475 } 476 unlock_map(&fs); 477 if (fs.m == vm_page_lookup(fs.object, 478 fs.pindex)) { 479 vm_page_sleep_if_busy(fs.m, "vmpfw"); 480 } 481 vm_object_pip_wakeup(fs.object); 482 VM_OBJECT_WUNLOCK(fs.object); 483 PCPU_INC(cnt.v_intrans); 484 vm_object_deallocate(fs.first_object); 485 goto RetryFault; 486 } 487 vm_page_lock(fs.m); 488 vm_page_remque(fs.m); 489 vm_page_unlock(fs.m); 490 491 /* 492 * Mark page busy for other processes, and the 493 * pagedaemon. If it still isn't completely valid 494 * (readable), jump to readrest, else break-out ( we 495 * found the page ). 496 */ 497 vm_page_xbusy(fs.m); 498 if (fs.m->valid != VM_PAGE_BITS_ALL) 499 goto readrest; 500 break; 501 } 502 503 /* 504 * Page is not resident, If this is the search termination 505 * or the pager might contain the page, allocate a new page. 506 */ 507 if (TRYPAGER || fs.object == fs.first_object) { 508 if (fs.pindex >= fs.object->size) { 509 unlock_and_deallocate(&fs); 510 return (KERN_PROTECTION_FAILURE); 511 } 512 513 /* 514 * Allocate a new page for this object/offset pair. 515 * 516 * Unlocked read of the p_flag is harmless. At 517 * worst, the P_KILLED might be not observed 518 * there, and allocation can fail, causing 519 * restart and new reading of the p_flag. 520 */ 521 fs.m = NULL; 522 if (!vm_page_count_severe() || P_KILLED(curproc)) { 523 #if VM_NRESERVLEVEL > 0 524 if ((fs.object->flags & OBJ_COLORED) == 0) { 525 fs.object->flags |= OBJ_COLORED; 526 fs.object->pg_color = atop(vaddr) - 527 fs.pindex; 528 } 529 #endif 530 alloc_req = P_KILLED(curproc) ? 531 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 532 if (fs.object->type != OBJT_VNODE && 533 fs.object->backing_object == NULL) 534 alloc_req |= VM_ALLOC_ZERO; 535 fs.m = vm_page_alloc(fs.object, fs.pindex, 536 alloc_req); 537 } 538 if (fs.m == NULL) { 539 unlock_and_deallocate(&fs); 540 VM_WAITPFAULT; 541 goto RetryFault; 542 } else if (fs.m->valid == VM_PAGE_BITS_ALL) 543 break; 544 } 545 546 readrest: 547 /* 548 * We have found a valid page or we have allocated a new page. 549 * The page thus may not be valid or may not be entirely 550 * valid. 551 * 552 * Attempt to fault-in the page if there is a chance that the 553 * pager has it, and potentially fault in additional pages 554 * at the same time. 555 */ 556 if (TRYPAGER) { 557 int rv; 558 u_char behavior = vm_map_entry_behavior(fs.entry); 559 560 era = fs.entry->read_ahead; 561 if (behavior == MAP_ENTRY_BEHAV_RANDOM || 562 P_KILLED(curproc)) { 563 behind = 0; 564 nera = 0; 565 ahead = 0; 566 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) { 567 behind = 0; 568 nera = VM_FAULT_READ_AHEAD_MAX; 569 ahead = nera; 570 if (fs.pindex == fs.entry->next_read) 571 vm_fault_cache_behind(&fs, 572 VM_FAULT_READ_MAX); 573 } else if (fs.pindex == fs.entry->next_read) { 574 /* 575 * This is a sequential fault. Arithmetically 576 * increase the requested number of pages in 577 * the read-ahead window. The requested 578 * number of pages is "# of sequential faults 579 * x (read ahead min + 1) + read ahead min" 580 */ 581 behind = 0; 582 nera = VM_FAULT_READ_AHEAD_MIN; 583 if (era > 0) { 584 nera += era + 1; 585 if (nera > VM_FAULT_READ_AHEAD_MAX) 586 nera = VM_FAULT_READ_AHEAD_MAX; 587 } 588 ahead = nera; 589 if (era == VM_FAULT_READ_AHEAD_MAX) 590 vm_fault_cache_behind(&fs, 591 VM_FAULT_CACHE_BEHIND); 592 } else { 593 /* 594 * This is a non-sequential fault. Request a 595 * cluster of pages that is aligned to a 596 * VM_FAULT_READ_DEFAULT page offset boundary 597 * within the object. Alignment to a page 598 * offset boundary is more likely to coincide 599 * with the underlying file system block than 600 * alignment to a virtual address boundary. 601 */ 602 cluster_offset = fs.pindex % 603 VM_FAULT_READ_DEFAULT; 604 behind = ulmin(cluster_offset, 605 atop(vaddr - fs.entry->start)); 606 nera = 0; 607 ahead = VM_FAULT_READ_DEFAULT - 1 - 608 cluster_offset; 609 } 610 ahead = ulmin(ahead, atop(fs.entry->end - vaddr) - 1); 611 if (era != nera) 612 fs.entry->read_ahead = nera; 613 614 /* 615 * Call the pager to retrieve the data, if any, after 616 * releasing the lock on the map. We hold a ref on 617 * fs.object and the pages are exclusive busied. 618 */ 619 unlock_map(&fs); 620 621 if (fs.object->type == OBJT_VNODE) { 622 vp = fs.object->handle; 623 if (vp == fs.vp) 624 goto vnode_locked; 625 else if (fs.vp != NULL) { 626 vput(fs.vp); 627 fs.vp = NULL; 628 } 629 locked = VOP_ISLOCKED(vp); 630 631 if (locked != LK_EXCLUSIVE) 632 locked = LK_SHARED; 633 /* Do not sleep for vnode lock while fs.m is busy */ 634 error = vget(vp, locked | LK_CANRECURSE | 635 LK_NOWAIT, curthread); 636 if (error != 0) { 637 vhold(vp); 638 release_page(&fs); 639 unlock_and_deallocate(&fs); 640 error = vget(vp, locked | LK_RETRY | 641 LK_CANRECURSE, curthread); 642 vdrop(vp); 643 fs.vp = vp; 644 KASSERT(error == 0, 645 ("vm_fault: vget failed")); 646 goto RetryFault; 647 } 648 fs.vp = vp; 649 } 650 vnode_locked: 651 KASSERT(fs.vp == NULL || !fs.map->system_map, 652 ("vm_fault: vnode-backed object mapped by system map")); 653 654 /* 655 * now we find out if any other pages should be paged 656 * in at this time this routine checks to see if the 657 * pages surrounding this fault reside in the same 658 * object as the page for this fault. If they do, 659 * then they are faulted in also into the object. The 660 * array "marray" returned contains an array of 661 * vm_page_t structs where one of them is the 662 * vm_page_t passed to the routine. The reqpage 663 * return value is the index into the marray for the 664 * vm_page_t passed to the routine. 665 * 666 * fs.m plus the additional pages are exclusive busied. 667 */ 668 faultcount = vm_fault_additional_pages( 669 fs.m, behind, ahead, marray, &reqpage); 670 671 rv = faultcount ? 672 vm_pager_get_pages(fs.object, marray, faultcount, 673 reqpage) : VM_PAGER_FAIL; 674 675 if (rv == VM_PAGER_OK) { 676 /* 677 * Found the page. Leave it busy while we play 678 * with it. 679 */ 680 681 /* 682 * Relookup in case pager changed page. Pager 683 * is responsible for disposition of old page 684 * if moved. 685 */ 686 fs.m = vm_page_lookup(fs.object, fs.pindex); 687 if (!fs.m) { 688 unlock_and_deallocate(&fs); 689 goto RetryFault; 690 } 691 692 hardfault++; 693 break; /* break to PAGE HAS BEEN FOUND */ 694 } 695 /* 696 * Remove the bogus page (which does not exist at this 697 * object/offset); before doing so, we must get back 698 * our object lock to preserve our invariant. 699 * 700 * Also wake up any other process that may want to bring 701 * in this page. 702 * 703 * If this is the top-level object, we must leave the 704 * busy page to prevent another process from rushing 705 * past us, and inserting the page in that object at 706 * the same time that we are. 707 */ 708 if (rv == VM_PAGER_ERROR) 709 printf("vm_fault: pager read error, pid %d (%s)\n", 710 curproc->p_pid, curproc->p_comm); 711 /* 712 * Data outside the range of the pager or an I/O error 713 */ 714 /* 715 * XXX - the check for kernel_map is a kludge to work 716 * around having the machine panic on a kernel space 717 * fault w/ I/O error. 718 */ 719 if (((fs.map != kernel_map) && (rv == VM_PAGER_ERROR)) || 720 (rv == VM_PAGER_BAD)) { 721 vm_page_lock(fs.m); 722 vm_page_free(fs.m); 723 vm_page_unlock(fs.m); 724 fs.m = NULL; 725 unlock_and_deallocate(&fs); 726 return ((rv == VM_PAGER_ERROR) ? KERN_FAILURE : KERN_PROTECTION_FAILURE); 727 } 728 if (fs.object != fs.first_object) { 729 vm_page_lock(fs.m); 730 vm_page_free(fs.m); 731 vm_page_unlock(fs.m); 732 fs.m = NULL; 733 /* 734 * XXX - we cannot just fall out at this 735 * point, m has been freed and is invalid! 736 */ 737 } 738 } 739 740 /* 741 * We get here if the object has default pager (or unwiring) 742 * or the pager doesn't have the page. 743 */ 744 if (fs.object == fs.first_object) 745 fs.first_m = fs.m; 746 747 /* 748 * Move on to the next object. Lock the next object before 749 * unlocking the current one. 750 */ 751 fs.pindex += OFF_TO_IDX(fs.object->backing_object_offset); 752 next_object = fs.object->backing_object; 753 if (next_object == NULL) { 754 /* 755 * If there's no object left, fill the page in the top 756 * object with zeros. 757 */ 758 if (fs.object != fs.first_object) { 759 vm_object_pip_wakeup(fs.object); 760 VM_OBJECT_WUNLOCK(fs.object); 761 762 fs.object = fs.first_object; 763 fs.pindex = fs.first_pindex; 764 fs.m = fs.first_m; 765 VM_OBJECT_WLOCK(fs.object); 766 } 767 fs.first_m = NULL; 768 769 /* 770 * Zero the page if necessary and mark it valid. 771 */ 772 if ((fs.m->flags & PG_ZERO) == 0) { 773 pmap_zero_page(fs.m); 774 } else { 775 PCPU_INC(cnt.v_ozfod); 776 } 777 PCPU_INC(cnt.v_zfod); 778 fs.m->valid = VM_PAGE_BITS_ALL; 779 /* Don't try to prefault neighboring pages. */ 780 faultcount = 1; 781 break; /* break to PAGE HAS BEEN FOUND */ 782 } else { 783 KASSERT(fs.object != next_object, 784 ("object loop %p", next_object)); 785 VM_OBJECT_WLOCK(next_object); 786 vm_object_pip_add(next_object, 1); 787 if (fs.object != fs.first_object) 788 vm_object_pip_wakeup(fs.object); 789 VM_OBJECT_WUNLOCK(fs.object); 790 fs.object = next_object; 791 } 792 } 793 794 vm_page_assert_xbusied(fs.m); 795 796 /* 797 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 798 * is held.] 799 */ 800 801 /* 802 * If the page is being written, but isn't already owned by the 803 * top-level object, we have to copy it into a new page owned by the 804 * top-level object. 805 */ 806 if (fs.object != fs.first_object) { 807 /* 808 * We only really need to copy if we want to write it. 809 */ 810 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 811 /* 812 * This allows pages to be virtually copied from a 813 * backing_object into the first_object, where the 814 * backing object has no other refs to it, and cannot 815 * gain any more refs. Instead of a bcopy, we just 816 * move the page from the backing object to the 817 * first object. Note that we must mark the page 818 * dirty in the first object so that it will go out 819 * to swap when needed. 820 */ 821 is_first_object_locked = FALSE; 822 if ( 823 /* 824 * Only one shadow object 825 */ 826 (fs.object->shadow_count == 1) && 827 /* 828 * No COW refs, except us 829 */ 830 (fs.object->ref_count == 1) && 831 /* 832 * No one else can look this object up 833 */ 834 (fs.object->handle == NULL) && 835 /* 836 * No other ways to look the object up 837 */ 838 ((fs.object->type == OBJT_DEFAULT) || 839 (fs.object->type == OBJT_SWAP)) && 840 (is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) && 841 /* 842 * We don't chase down the shadow chain 843 */ 844 fs.object == fs.first_object->backing_object) { 845 /* 846 * get rid of the unnecessary page 847 */ 848 vm_page_lock(fs.first_m); 849 vm_page_free(fs.first_m); 850 vm_page_unlock(fs.first_m); 851 /* 852 * grab the page and put it into the 853 * process'es object. The page is 854 * automatically made dirty. 855 */ 856 if (vm_page_rename(fs.m, fs.first_object, 857 fs.first_pindex)) { 858 unlock_and_deallocate(&fs); 859 goto RetryFault; 860 } 861 vm_page_xbusy(fs.m); 862 fs.first_m = fs.m; 863 fs.m = NULL; 864 PCPU_INC(cnt.v_cow_optim); 865 } else { 866 /* 867 * Oh, well, lets copy it. 868 */ 869 pmap_copy_page(fs.m, fs.first_m); 870 fs.first_m->valid = VM_PAGE_BITS_ALL; 871 if (wired && (fault_flags & 872 VM_FAULT_CHANGE_WIRING) == 0) { 873 vm_page_lock(fs.first_m); 874 vm_page_wire(fs.first_m); 875 vm_page_unlock(fs.first_m); 876 877 vm_page_lock(fs.m); 878 vm_page_unwire(fs.m, PQ_INACTIVE); 879 vm_page_unlock(fs.m); 880 } 881 /* 882 * We no longer need the old page or object. 883 */ 884 release_page(&fs); 885 } 886 /* 887 * fs.object != fs.first_object due to above 888 * conditional 889 */ 890 vm_object_pip_wakeup(fs.object); 891 VM_OBJECT_WUNLOCK(fs.object); 892 /* 893 * Only use the new page below... 894 */ 895 fs.object = fs.first_object; 896 fs.pindex = fs.first_pindex; 897 fs.m = fs.first_m; 898 if (!is_first_object_locked) 899 VM_OBJECT_WLOCK(fs.object); 900 PCPU_INC(cnt.v_cow_faults); 901 curthread->td_cow++; 902 } else { 903 prot &= ~VM_PROT_WRITE; 904 } 905 } 906 907 /* 908 * We must verify that the maps have not changed since our last 909 * lookup. 910 */ 911 if (!fs.lookup_still_valid) { 912 vm_object_t retry_object; 913 vm_pindex_t retry_pindex; 914 vm_prot_t retry_prot; 915 916 if (!vm_map_trylock_read(fs.map)) { 917 release_page(&fs); 918 unlock_and_deallocate(&fs); 919 goto RetryFault; 920 } 921 fs.lookup_still_valid = TRUE; 922 if (fs.map->timestamp != map_generation) { 923 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 924 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 925 926 /* 927 * If we don't need the page any longer, put it on the inactive 928 * list (the easiest thing to do here). If no one needs it, 929 * pageout will grab it eventually. 930 */ 931 if (result != KERN_SUCCESS) { 932 release_page(&fs); 933 unlock_and_deallocate(&fs); 934 935 /* 936 * If retry of map lookup would have blocked then 937 * retry fault from start. 938 */ 939 if (result == KERN_FAILURE) 940 goto RetryFault; 941 return (result); 942 } 943 if ((retry_object != fs.first_object) || 944 (retry_pindex != fs.first_pindex)) { 945 release_page(&fs); 946 unlock_and_deallocate(&fs); 947 goto RetryFault; 948 } 949 950 /* 951 * Check whether the protection has changed or the object has 952 * been copied while we left the map unlocked. Changing from 953 * read to write permission is OK - we leave the page 954 * write-protected, and catch the write fault. Changing from 955 * write to read permission means that we can't mark the page 956 * write-enabled after all. 957 */ 958 prot &= retry_prot; 959 } 960 } 961 /* 962 * If the page was filled by a pager, update the map entry's 963 * last read offset. Since the pager does not return the 964 * actual set of pages that it read, this update is based on 965 * the requested set. Typically, the requested and actual 966 * sets are the same. 967 * 968 * XXX The following assignment modifies the map 969 * without holding a write lock on it. 970 */ 971 if (hardfault) 972 fs.entry->next_read = fs.pindex + faultcount - reqpage; 973 974 vm_fault_dirty(fs.entry, fs.m, prot, fault_type, fault_flags, TRUE); 975 vm_page_assert_xbusied(fs.m); 976 977 /* 978 * Page must be completely valid or it is not fit to 979 * map into user space. vm_pager_get_pages() ensures this. 980 */ 981 KASSERT(fs.m->valid == VM_PAGE_BITS_ALL, 982 ("vm_fault: page %p partially invalid", fs.m)); 983 VM_OBJECT_WUNLOCK(fs.object); 984 985 /* 986 * Put this page into the physical map. We had to do the unlock above 987 * because pmap_enter() may sleep. We don't put the page 988 * back on the active queue until later so that the pageout daemon 989 * won't find it (yet). 990 */ 991 pmap_enter(fs.map->pmap, vaddr, fs.m, prot, 992 fault_type | (wired ? PMAP_ENTER_WIRED : 0), 0); 993 if (faultcount != 1 && (fault_flags & VM_FAULT_CHANGE_WIRING) == 0 && 994 wired == 0) 995 vm_fault_prefault(&fs, vaddr, faultcount, reqpage); 996 VM_OBJECT_WLOCK(fs.object); 997 vm_page_lock(fs.m); 998 999 /* 1000 * If the page is not wired down, then put it where the pageout daemon 1001 * can find it. 1002 */ 1003 if (fault_flags & VM_FAULT_CHANGE_WIRING) { 1004 if (wired) 1005 vm_page_wire(fs.m); 1006 else 1007 vm_page_unwire(fs.m, PQ_ACTIVE); 1008 } else 1009 vm_page_activate(fs.m); 1010 if (m_hold != NULL) { 1011 *m_hold = fs.m; 1012 vm_page_hold(fs.m); 1013 } 1014 vm_page_unlock(fs.m); 1015 vm_page_xunbusy(fs.m); 1016 1017 /* 1018 * Unlock everything, and return 1019 */ 1020 unlock_and_deallocate(&fs); 1021 if (hardfault) { 1022 PCPU_INC(cnt.v_io_faults); 1023 curthread->td_ru.ru_majflt++; 1024 } else 1025 curthread->td_ru.ru_minflt++; 1026 1027 return (KERN_SUCCESS); 1028 } 1029 1030 /* 1031 * Speed up the reclamation of up to "distance" pages that precede the 1032 * faulting pindex within the first object of the shadow chain. 1033 */ 1034 static void 1035 vm_fault_cache_behind(const struct faultstate *fs, int distance) 1036 { 1037 vm_object_t first_object, object; 1038 vm_page_t m, m_prev; 1039 vm_pindex_t pindex; 1040 1041 object = fs->object; 1042 VM_OBJECT_ASSERT_WLOCKED(object); 1043 first_object = fs->first_object; 1044 if (first_object != object) { 1045 if (!VM_OBJECT_TRYWLOCK(first_object)) { 1046 VM_OBJECT_WUNLOCK(object); 1047 VM_OBJECT_WLOCK(first_object); 1048 VM_OBJECT_WLOCK(object); 1049 } 1050 } 1051 /* Neither fictitious nor unmanaged pages can be cached. */ 1052 if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) { 1053 if (fs->first_pindex < distance) 1054 pindex = 0; 1055 else 1056 pindex = fs->first_pindex - distance; 1057 if (pindex < OFF_TO_IDX(fs->entry->offset)) 1058 pindex = OFF_TO_IDX(fs->entry->offset); 1059 m = first_object != object ? fs->first_m : fs->m; 1060 vm_page_assert_xbusied(m); 1061 m_prev = vm_page_prev(m); 1062 while ((m = m_prev) != NULL && m->pindex >= pindex && 1063 m->valid == VM_PAGE_BITS_ALL) { 1064 m_prev = vm_page_prev(m); 1065 if (vm_page_busied(m)) 1066 continue; 1067 vm_page_lock(m); 1068 if (m->hold_count == 0 && m->wire_count == 0) { 1069 pmap_remove_all(m); 1070 vm_page_aflag_clear(m, PGA_REFERENCED); 1071 if (m->dirty != 0) 1072 vm_page_deactivate(m); 1073 else 1074 vm_page_cache(m); 1075 } 1076 vm_page_unlock(m); 1077 } 1078 } 1079 if (first_object != object) 1080 VM_OBJECT_WUNLOCK(first_object); 1081 } 1082 1083 /* 1084 * vm_fault_prefault provides a quick way of clustering 1085 * pagefaults into a processes address space. It is a "cousin" 1086 * of vm_map_pmap_enter, except it runs at page fault time instead 1087 * of mmap time. 1088 */ 1089 static void 1090 vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra, 1091 int faultcount, int reqpage) 1092 { 1093 pmap_t pmap; 1094 vm_map_entry_t entry; 1095 vm_object_t backing_object, lobject; 1096 vm_offset_t addr, starta; 1097 vm_pindex_t pindex; 1098 vm_page_t m; 1099 int backward, forward, i; 1100 1101 pmap = fs->map->pmap; 1102 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 1103 return; 1104 1105 if (faultcount > 0) { 1106 backward = reqpage; 1107 forward = faultcount - reqpage - 1; 1108 } else { 1109 backward = PFBAK; 1110 forward = PFFOR; 1111 } 1112 entry = fs->entry; 1113 1114 starta = addra - backward * PAGE_SIZE; 1115 if (starta < entry->start) { 1116 starta = entry->start; 1117 } else if (starta > addra) { 1118 starta = 0; 1119 } 1120 1121 /* 1122 * Generate the sequence of virtual addresses that are candidates for 1123 * prefaulting in an outward spiral from the faulting virtual address, 1124 * "addra". Specifically, the sequence is "addra - PAGE_SIZE", "addra 1125 * + PAGE_SIZE", "addra - 2 * PAGE_SIZE", "addra + 2 * PAGE_SIZE", ... 1126 * If the candidate address doesn't have a backing physical page, then 1127 * the loop immediately terminates. 1128 */ 1129 for (i = 0; i < 2 * imax(backward, forward); i++) { 1130 addr = addra + ((i >> 1) + 1) * ((i & 1) == 0 ? -PAGE_SIZE : 1131 PAGE_SIZE); 1132 if (addr > addra + forward * PAGE_SIZE) 1133 addr = 0; 1134 1135 if (addr < starta || addr >= entry->end) 1136 continue; 1137 1138 if (!pmap_is_prefaultable(pmap, addr)) 1139 continue; 1140 1141 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1142 lobject = entry->object.vm_object; 1143 VM_OBJECT_RLOCK(lobject); 1144 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1145 lobject->type == OBJT_DEFAULT && 1146 (backing_object = lobject->backing_object) != NULL) { 1147 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1148 0, ("vm_fault_prefault: unaligned object offset")); 1149 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1150 VM_OBJECT_RLOCK(backing_object); 1151 VM_OBJECT_RUNLOCK(lobject); 1152 lobject = backing_object; 1153 } 1154 if (m == NULL) { 1155 VM_OBJECT_RUNLOCK(lobject); 1156 break; 1157 } 1158 if (m->valid == VM_PAGE_BITS_ALL && 1159 (m->flags & PG_FICTITIOUS) == 0) 1160 pmap_enter_quick(pmap, addr, m, entry->protection); 1161 VM_OBJECT_RUNLOCK(lobject); 1162 } 1163 } 1164 1165 /* 1166 * Hold each of the physical pages that are mapped by the specified range of 1167 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid 1168 * and allow the specified types of access, "prot". If all of the implied 1169 * pages are successfully held, then the number of held pages is returned 1170 * together with pointers to those pages in the array "ma". However, if any 1171 * of the pages cannot be held, -1 is returned. 1172 */ 1173 int 1174 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len, 1175 vm_prot_t prot, vm_page_t *ma, int max_count) 1176 { 1177 vm_offset_t end, va; 1178 vm_page_t *mp; 1179 int count; 1180 boolean_t pmap_failed; 1181 1182 if (len == 0) 1183 return (0); 1184 end = round_page(addr + len); 1185 addr = trunc_page(addr); 1186 1187 /* 1188 * Check for illegal addresses. 1189 */ 1190 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map)) 1191 return (-1); 1192 1193 if (atop(end - addr) > max_count) 1194 panic("vm_fault_quick_hold_pages: count > max_count"); 1195 count = atop(end - addr); 1196 1197 /* 1198 * Most likely, the physical pages are resident in the pmap, so it is 1199 * faster to try pmap_extract_and_hold() first. 1200 */ 1201 pmap_failed = FALSE; 1202 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) { 1203 *mp = pmap_extract_and_hold(map->pmap, va, prot); 1204 if (*mp == NULL) 1205 pmap_failed = TRUE; 1206 else if ((prot & VM_PROT_WRITE) != 0 && 1207 (*mp)->dirty != VM_PAGE_BITS_ALL) { 1208 /* 1209 * Explicitly dirty the physical page. Otherwise, the 1210 * caller's changes may go unnoticed because they are 1211 * performed through an unmanaged mapping or by a DMA 1212 * operation. 1213 * 1214 * The object lock is not held here. 1215 * See vm_page_clear_dirty_mask(). 1216 */ 1217 vm_page_dirty(*mp); 1218 } 1219 } 1220 if (pmap_failed) { 1221 /* 1222 * One or more pages could not be held by the pmap. Either no 1223 * page was mapped at the specified virtual address or that 1224 * mapping had insufficient permissions. Attempt to fault in 1225 * and hold these pages. 1226 */ 1227 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) 1228 if (*mp == NULL && vm_fault_hold(map, va, prot, 1229 VM_FAULT_NORMAL, mp) != KERN_SUCCESS) 1230 goto error; 1231 } 1232 return (count); 1233 error: 1234 for (mp = ma; mp < ma + count; mp++) 1235 if (*mp != NULL) { 1236 vm_page_lock(*mp); 1237 vm_page_unhold(*mp); 1238 vm_page_unlock(*mp); 1239 } 1240 return (-1); 1241 } 1242 1243 /* 1244 * Routine: 1245 * vm_fault_copy_entry 1246 * Function: 1247 * Create new shadow object backing dst_entry with private copy of 1248 * all underlying pages. When src_entry is equal to dst_entry, 1249 * function implements COW for wired-down map entry. Otherwise, 1250 * it forks wired entry into dst_map. 1251 * 1252 * In/out conditions: 1253 * The source and destination maps must be locked for write. 1254 * The source map entry must be wired down (or be a sharing map 1255 * entry corresponding to a main map entry that is wired down). 1256 */ 1257 void 1258 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1259 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1260 vm_ooffset_t *fork_charge) 1261 { 1262 vm_object_t backing_object, dst_object, object, src_object; 1263 vm_pindex_t dst_pindex, pindex, src_pindex; 1264 vm_prot_t access, prot; 1265 vm_offset_t vaddr; 1266 vm_page_t dst_m; 1267 vm_page_t src_m; 1268 boolean_t upgrade; 1269 1270 #ifdef lint 1271 src_map++; 1272 #endif /* lint */ 1273 1274 upgrade = src_entry == dst_entry; 1275 access = prot = dst_entry->protection; 1276 1277 src_object = src_entry->object.vm_object; 1278 src_pindex = OFF_TO_IDX(src_entry->offset); 1279 1280 if (upgrade && (dst_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) { 1281 dst_object = src_object; 1282 vm_object_reference(dst_object); 1283 } else { 1284 /* 1285 * Create the top-level object for the destination entry. (Doesn't 1286 * actually shadow anything - we copy the pages directly.) 1287 */ 1288 dst_object = vm_object_allocate(OBJT_DEFAULT, 1289 OFF_TO_IDX(dst_entry->end - dst_entry->start)); 1290 #if VM_NRESERVLEVEL > 0 1291 dst_object->flags |= OBJ_COLORED; 1292 dst_object->pg_color = atop(dst_entry->start); 1293 #endif 1294 } 1295 1296 VM_OBJECT_WLOCK(dst_object); 1297 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1298 ("vm_fault_copy_entry: vm_object not NULL")); 1299 if (src_object != dst_object) { 1300 dst_entry->object.vm_object = dst_object; 1301 dst_entry->offset = 0; 1302 dst_object->charge = dst_entry->end - dst_entry->start; 1303 } 1304 if (fork_charge != NULL) { 1305 KASSERT(dst_entry->cred == NULL, 1306 ("vm_fault_copy_entry: leaked swp charge")); 1307 dst_object->cred = curthread->td_ucred; 1308 crhold(dst_object->cred); 1309 *fork_charge += dst_object->charge; 1310 } else if (dst_object->cred == NULL) { 1311 KASSERT(dst_entry->cred != NULL, ("no cred for entry %p", 1312 dst_entry)); 1313 dst_object->cred = dst_entry->cred; 1314 dst_entry->cred = NULL; 1315 } 1316 1317 /* 1318 * If not an upgrade, then enter the mappings in the pmap as 1319 * read and/or execute accesses. Otherwise, enter them as 1320 * write accesses. 1321 * 1322 * A writeable large page mapping is only created if all of 1323 * the constituent small page mappings are modified. Marking 1324 * PTEs as modified on inception allows promotion to happen 1325 * without taking potentially large number of soft faults. 1326 */ 1327 if (!upgrade) 1328 access &= ~VM_PROT_WRITE; 1329 1330 /* 1331 * Loop through all of the virtual pages within the entry's 1332 * range, copying each page from the source object to the 1333 * destination object. Since the source is wired, those pages 1334 * must exist. In contrast, the destination is pageable. 1335 * Since the destination object does share any backing storage 1336 * with the source object, all of its pages must be dirtied, 1337 * regardless of whether they can be written. 1338 */ 1339 for (vaddr = dst_entry->start, dst_pindex = 0; 1340 vaddr < dst_entry->end; 1341 vaddr += PAGE_SIZE, dst_pindex++) { 1342 again: 1343 /* 1344 * Find the page in the source object, and copy it in. 1345 * Because the source is wired down, the page will be 1346 * in memory. 1347 */ 1348 if (src_object != dst_object) 1349 VM_OBJECT_RLOCK(src_object); 1350 object = src_object; 1351 pindex = src_pindex + dst_pindex; 1352 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1353 (backing_object = object->backing_object) != NULL) { 1354 /* 1355 * Unless the source mapping is read-only or 1356 * it is presently being upgraded from 1357 * read-only, the first object in the shadow 1358 * chain should provide all of the pages. In 1359 * other words, this loop body should never be 1360 * executed when the source mapping is already 1361 * read/write. 1362 */ 1363 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 || 1364 upgrade, 1365 ("vm_fault_copy_entry: main object missing page")); 1366 1367 VM_OBJECT_RLOCK(backing_object); 1368 pindex += OFF_TO_IDX(object->backing_object_offset); 1369 if (object != dst_object) 1370 VM_OBJECT_RUNLOCK(object); 1371 object = backing_object; 1372 } 1373 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing")); 1374 1375 if (object != dst_object) { 1376 /* 1377 * Allocate a page in the destination object. 1378 */ 1379 dst_m = vm_page_alloc(dst_object, (src_object == 1380 dst_object ? src_pindex : 0) + dst_pindex, 1381 VM_ALLOC_NORMAL); 1382 if (dst_m == NULL) { 1383 VM_OBJECT_WUNLOCK(dst_object); 1384 VM_OBJECT_RUNLOCK(object); 1385 VM_WAIT; 1386 VM_OBJECT_WLOCK(dst_object); 1387 goto again; 1388 } 1389 pmap_copy_page(src_m, dst_m); 1390 VM_OBJECT_RUNLOCK(object); 1391 dst_m->valid = VM_PAGE_BITS_ALL; 1392 dst_m->dirty = VM_PAGE_BITS_ALL; 1393 } else { 1394 dst_m = src_m; 1395 if (vm_page_sleep_if_busy(dst_m, "fltupg")) 1396 goto again; 1397 vm_page_xbusy(dst_m); 1398 KASSERT(dst_m->valid == VM_PAGE_BITS_ALL, 1399 ("invalid dst page %p", dst_m)); 1400 } 1401 VM_OBJECT_WUNLOCK(dst_object); 1402 1403 /* 1404 * Enter it in the pmap. If a wired, copy-on-write 1405 * mapping is being replaced by a write-enabled 1406 * mapping, then wire that new mapping. 1407 */ 1408 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, 1409 access | (upgrade ? PMAP_ENTER_WIRED : 0), 0); 1410 1411 /* 1412 * Mark it no longer busy, and put it on the active list. 1413 */ 1414 VM_OBJECT_WLOCK(dst_object); 1415 1416 if (upgrade) { 1417 if (src_m != dst_m) { 1418 vm_page_lock(src_m); 1419 vm_page_unwire(src_m, PQ_INACTIVE); 1420 vm_page_unlock(src_m); 1421 vm_page_lock(dst_m); 1422 vm_page_wire(dst_m); 1423 vm_page_unlock(dst_m); 1424 } else { 1425 KASSERT(dst_m->wire_count > 0, 1426 ("dst_m %p is not wired", dst_m)); 1427 } 1428 } else { 1429 vm_page_lock(dst_m); 1430 vm_page_activate(dst_m); 1431 vm_page_unlock(dst_m); 1432 } 1433 vm_page_xunbusy(dst_m); 1434 } 1435 VM_OBJECT_WUNLOCK(dst_object); 1436 if (upgrade) { 1437 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1438 vm_object_deallocate(src_object); 1439 } 1440 } 1441 1442 1443 /* 1444 * This routine checks around the requested page for other pages that 1445 * might be able to be faulted in. This routine brackets the viable 1446 * pages for the pages to be paged in. 1447 * 1448 * Inputs: 1449 * m, rbehind, rahead 1450 * 1451 * Outputs: 1452 * marray (array of vm_page_t), reqpage (index of requested page) 1453 * 1454 * Return value: 1455 * number of pages in marray 1456 */ 1457 static int 1458 vm_fault_additional_pages(m, rbehind, rahead, marray, reqpage) 1459 vm_page_t m; 1460 int rbehind; 1461 int rahead; 1462 vm_page_t *marray; 1463 int *reqpage; 1464 { 1465 int i,j; 1466 vm_object_t object; 1467 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1468 vm_page_t rtm; 1469 int cbehind, cahead; 1470 1471 VM_OBJECT_ASSERT_WLOCKED(m->object); 1472 1473 object = m->object; 1474 pindex = m->pindex; 1475 cbehind = cahead = 0; 1476 1477 /* 1478 * if the requested page is not available, then give up now 1479 */ 1480 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1481 return 0; 1482 } 1483 1484 if ((cbehind == 0) && (cahead == 0)) { 1485 *reqpage = 0; 1486 marray[0] = m; 1487 return 1; 1488 } 1489 1490 if (rahead > cahead) { 1491 rahead = cahead; 1492 } 1493 1494 if (rbehind > cbehind) { 1495 rbehind = cbehind; 1496 } 1497 1498 /* 1499 * scan backward for the read behind pages -- in memory 1500 */ 1501 if (pindex > 0) { 1502 if (rbehind > pindex) { 1503 rbehind = pindex; 1504 startpindex = 0; 1505 } else { 1506 startpindex = pindex - rbehind; 1507 } 1508 1509 if ((rtm = TAILQ_PREV(m, pglist, listq)) != NULL && 1510 rtm->pindex >= startpindex) 1511 startpindex = rtm->pindex + 1; 1512 1513 /* tpindex is unsigned; beware of numeric underflow. */ 1514 for (i = 0, tpindex = pindex - 1; tpindex >= startpindex && 1515 tpindex < pindex; i++, tpindex--) { 1516 1517 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1518 VM_ALLOC_IFNOTCACHED); 1519 if (rtm == NULL) { 1520 /* 1521 * Shift the allocated pages to the 1522 * beginning of the array. 1523 */ 1524 for (j = 0; j < i; j++) { 1525 marray[j] = marray[j + tpindex + 1 - 1526 startpindex]; 1527 } 1528 break; 1529 } 1530 1531 marray[tpindex - startpindex] = rtm; 1532 } 1533 } else { 1534 startpindex = 0; 1535 i = 0; 1536 } 1537 1538 marray[i] = m; 1539 /* page offset of the required page */ 1540 *reqpage = i; 1541 1542 tpindex = pindex + 1; 1543 i++; 1544 1545 /* 1546 * scan forward for the read ahead pages 1547 */ 1548 endpindex = tpindex + rahead; 1549 if ((rtm = TAILQ_NEXT(m, listq)) != NULL && rtm->pindex < endpindex) 1550 endpindex = rtm->pindex; 1551 if (endpindex > object->size) 1552 endpindex = object->size; 1553 1554 for (; tpindex < endpindex; i++, tpindex++) { 1555 1556 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_NORMAL | 1557 VM_ALLOC_IFNOTCACHED); 1558 if (rtm == NULL) { 1559 break; 1560 } 1561 1562 marray[i] = rtm; 1563 } 1564 1565 /* return number of pages */ 1566 return i; 1567 } 1568 1569 /* 1570 * Block entry into the machine-independent layer's page fault handler by 1571 * the calling thread. Subsequent calls to vm_fault() by that thread will 1572 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of 1573 * spurious page faults. 1574 */ 1575 int 1576 vm_fault_disable_pagefaults(void) 1577 { 1578 1579 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR)); 1580 } 1581 1582 void 1583 vm_fault_enable_pagefaults(int save) 1584 { 1585 1586 curthread_pflags_restore(save); 1587 } 1588