1 /*- 2 * SPDX-License-Identifier: (BSD-4-Clause AND MIT-CMU) 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * Copyright (c) 1994 John S. Dyson 7 * All rights reserved. 8 * Copyright (c) 1994 David Greenman 9 * All rights reserved. 10 * 11 * 12 * This code is derived from software contributed to Berkeley by 13 * The Mach Operating System project at Carnegie-Mellon University. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 3. All advertising materials mentioning features or use of this software 24 * must display the following acknowledgement: 25 * This product includes software developed by the University of 26 * California, Berkeley and its contributors. 27 * 4. Neither the name of the University nor the names of its contributors 28 * may be used to endorse or promote products derived from this software 29 * without specific prior written permission. 30 * 31 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 32 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 33 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 34 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 35 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 39 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 40 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 41 * SUCH DAMAGE. 42 * 43 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94 44 * 45 * 46 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 47 * All rights reserved. 48 * 49 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 50 * 51 * Permission to use, copy, modify and distribute this software and 52 * its documentation is hereby granted, provided that both the copyright 53 * notice and this permission notice appear in all copies of the 54 * software, derivative works or modified versions, and any portions 55 * thereof, and that both notices appear in supporting documentation. 56 * 57 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 58 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 59 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 60 * 61 * Carnegie Mellon requests users of this software to return to 62 * 63 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 64 * School of Computer Science 65 * Carnegie Mellon University 66 * Pittsburgh PA 15213-3890 67 * 68 * any improvements or extensions that they make and grant Carnegie the 69 * rights to redistribute these changes. 70 */ 71 72 /* 73 * Page fault handling module. 74 */ 75 76 #include <sys/cdefs.h> 77 __FBSDID("$FreeBSD$"); 78 79 #include "opt_ktrace.h" 80 #include "opt_vm.h" 81 82 #include <sys/param.h> 83 #include <sys/systm.h> 84 #include <sys/kernel.h> 85 #include <sys/lock.h> 86 #include <sys/mman.h> 87 #include <sys/mutex.h> 88 #include <sys/proc.h> 89 #include <sys/racct.h> 90 #include <sys/refcount.h> 91 #include <sys/resourcevar.h> 92 #include <sys/rwlock.h> 93 #include <sys/signalvar.h> 94 #include <sys/sysctl.h> 95 #include <sys/sysent.h> 96 #include <sys/vmmeter.h> 97 #include <sys/vnode.h> 98 #ifdef KTRACE 99 #include <sys/ktrace.h> 100 #endif 101 102 #include <vm/vm.h> 103 #include <vm/vm_param.h> 104 #include <vm/pmap.h> 105 #include <vm/vm_map.h> 106 #include <vm/vm_object.h> 107 #include <vm/vm_page.h> 108 #include <vm/vm_pageout.h> 109 #include <vm/vm_kern.h> 110 #include <vm/vm_pager.h> 111 #include <vm/vm_extern.h> 112 #include <vm/vm_reserv.h> 113 114 #define PFBAK 4 115 #define PFFOR 4 116 117 #define VM_FAULT_READ_DEFAULT (1 + VM_FAULT_READ_AHEAD_INIT) 118 #define VM_FAULT_READ_MAX (1 + VM_FAULT_READ_AHEAD_MAX) 119 120 #define VM_FAULT_DONTNEED_MIN 1048576 121 122 struct faultstate { 123 vm_page_t m; 124 vm_object_t object; 125 vm_pindex_t pindex; 126 vm_page_t first_m; 127 vm_object_t first_object; 128 vm_pindex_t first_pindex; 129 vm_map_t map; 130 vm_map_entry_t entry; 131 int map_generation; 132 bool lookup_still_valid; 133 struct vnode *vp; 134 }; 135 136 static void vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr, 137 int ahead); 138 static void vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra, 139 int backward, int forward, bool obj_locked); 140 141 static int vm_pfault_oom_attempts = 3; 142 SYSCTL_INT(_vm, OID_AUTO, pfault_oom_attempts, CTLFLAG_RWTUN, 143 &vm_pfault_oom_attempts, 0, 144 "Number of page allocation attempts in page fault handler before it " 145 "triggers OOM handling"); 146 147 static int vm_pfault_oom_wait = 10; 148 SYSCTL_INT(_vm, OID_AUTO, pfault_oom_wait, CTLFLAG_RWTUN, 149 &vm_pfault_oom_wait, 0, 150 "Number of seconds to wait for free pages before retrying " 151 "the page fault handler"); 152 153 static inline void 154 release_page(struct faultstate *fs) 155 { 156 157 if (fs->m != NULL) { 158 /* 159 * fs->m's object lock might not be held, so the page must be 160 * kept busy until we are done with it. 161 */ 162 vm_page_lock(fs->m); 163 vm_page_deactivate(fs->m); 164 vm_page_unlock(fs->m); 165 vm_page_xunbusy(fs->m); 166 fs->m = NULL; 167 } 168 } 169 170 static inline void 171 unlock_map(struct faultstate *fs) 172 { 173 174 if (fs->lookup_still_valid) { 175 vm_map_lookup_done(fs->map, fs->entry); 176 fs->lookup_still_valid = false; 177 } 178 } 179 180 static void 181 unlock_vp(struct faultstate *fs) 182 { 183 184 if (fs->vp != NULL) { 185 vput(fs->vp); 186 fs->vp = NULL; 187 } 188 } 189 190 static void 191 fault_deallocate(struct faultstate *fs) 192 { 193 194 vm_object_pip_wakeup(fs->object); 195 if (fs->object != fs->first_object) { 196 VM_OBJECT_WLOCK(fs->first_object); 197 vm_page_free(fs->first_m); 198 vm_object_pip_wakeup(fs->first_object); 199 VM_OBJECT_WUNLOCK(fs->first_object); 200 fs->first_m = NULL; 201 } 202 vm_object_deallocate(fs->first_object); 203 unlock_map(fs); 204 unlock_vp(fs); 205 } 206 207 static void 208 unlock_and_deallocate(struct faultstate *fs) 209 { 210 211 VM_OBJECT_WUNLOCK(fs->object); 212 fault_deallocate(fs); 213 } 214 215 static void 216 vm_fault_dirty(vm_map_entry_t entry, vm_page_t m, vm_prot_t prot, 217 vm_prot_t fault_type, int fault_flags, bool excl) 218 { 219 bool need_dirty; 220 221 if (((prot & VM_PROT_WRITE) == 0 && 222 (fault_flags & VM_FAULT_DIRTY) == 0) || 223 (m->oflags & VPO_UNMANAGED) != 0) 224 return; 225 226 VM_OBJECT_ASSERT_LOCKED(m->object); 227 VM_PAGE_OBJECT_BUSY_ASSERT(m); 228 229 need_dirty = ((fault_type & VM_PROT_WRITE) != 0 && 230 (fault_flags & VM_FAULT_WIRE) == 0) || 231 (fault_flags & VM_FAULT_DIRTY) != 0; 232 233 vm_object_set_writeable_dirty(m->object); 234 235 if (!excl) 236 /* 237 * If two callers of vm_fault_dirty() with excl == 238 * FALSE, one for the map entry with MAP_ENTRY_NOSYNC 239 * flag set, other with flag clear, race, it is 240 * possible for the no-NOSYNC thread to see m->dirty 241 * != 0 and not clear PGA_NOSYNC. Take vm_page lock 242 * around manipulation of PGA_NOSYNC and 243 * vm_page_dirty() call to avoid the race. 244 */ 245 vm_page_lock(m); 246 247 /* 248 * If this is a NOSYNC mmap we do not want to set PGA_NOSYNC 249 * if the page is already dirty to prevent data written with 250 * the expectation of being synced from not being synced. 251 * Likewise if this entry does not request NOSYNC then make 252 * sure the page isn't marked NOSYNC. Applications sharing 253 * data should use the same flags to avoid ping ponging. 254 */ 255 if ((entry->eflags & MAP_ENTRY_NOSYNC) != 0) { 256 if (m->dirty == 0) { 257 vm_page_aflag_set(m, PGA_NOSYNC); 258 } 259 } else { 260 vm_page_aflag_clear(m, PGA_NOSYNC); 261 } 262 263 /* 264 * If the fault is a write, we know that this page is being 265 * written NOW so dirty it explicitly to save on 266 * pmap_is_modified() calls later. 267 * 268 * Also, since the page is now dirty, we can possibly tell 269 * the pager to release any swap backing the page. Calling 270 * the pager requires a write lock on the object. 271 */ 272 if (need_dirty) 273 vm_page_dirty(m); 274 if (!excl) 275 vm_page_unlock(m); 276 else if (need_dirty) 277 vm_pager_page_unswapped(m); 278 } 279 280 /* 281 * Unlocks fs.first_object and fs.map on success. 282 */ 283 static int 284 vm_fault_soft_fast(struct faultstate *fs, vm_offset_t vaddr, vm_prot_t prot, 285 int fault_type, int fault_flags, boolean_t wired, vm_page_t *m_hold) 286 { 287 vm_page_t m, m_map; 288 #if (defined(__aarch64__) || defined(__amd64__) || (defined(__arm__) && \ 289 __ARM_ARCH >= 6) || defined(__i386__) || defined(__riscv)) && \ 290 VM_NRESERVLEVEL > 0 291 vm_page_t m_super; 292 int flags; 293 #endif 294 int psind, rv; 295 296 MPASS(fs->vp == NULL); 297 vm_object_busy(fs->first_object); 298 m = vm_page_lookup(fs->first_object, fs->first_pindex); 299 /* A busy page can be mapped for read|execute access. */ 300 if (m == NULL || ((prot & VM_PROT_WRITE) != 0 && 301 vm_page_busied(m)) || !vm_page_all_valid(m)) { 302 rv = KERN_FAILURE; 303 goto out; 304 } 305 m_map = m; 306 psind = 0; 307 #if (defined(__aarch64__) || defined(__amd64__) || (defined(__arm__) && \ 308 __ARM_ARCH >= 6) || defined(__i386__) || defined(__riscv)) && \ 309 VM_NRESERVLEVEL > 0 310 if ((m->flags & PG_FICTITIOUS) == 0 && 311 (m_super = vm_reserv_to_superpage(m)) != NULL && 312 rounddown2(vaddr, pagesizes[m_super->psind]) >= fs->entry->start && 313 roundup2(vaddr + 1, pagesizes[m_super->psind]) <= fs->entry->end && 314 (vaddr & (pagesizes[m_super->psind] - 1)) == (VM_PAGE_TO_PHYS(m) & 315 (pagesizes[m_super->psind] - 1)) && !wired && 316 pmap_ps_enabled(fs->map->pmap)) { 317 flags = PS_ALL_VALID; 318 if ((prot & VM_PROT_WRITE) != 0) { 319 /* 320 * Create a superpage mapping allowing write access 321 * only if none of the constituent pages are busy and 322 * all of them are already dirty (except possibly for 323 * the page that was faulted on). 324 */ 325 flags |= PS_NONE_BUSY; 326 if ((fs->first_object->flags & OBJ_UNMANAGED) == 0) 327 flags |= PS_ALL_DIRTY; 328 } 329 if (vm_page_ps_test(m_super, flags, m)) { 330 m_map = m_super; 331 psind = m_super->psind; 332 vaddr = rounddown2(vaddr, pagesizes[psind]); 333 /* Preset the modified bit for dirty superpages. */ 334 if ((flags & PS_ALL_DIRTY) != 0) 335 fault_type |= VM_PROT_WRITE; 336 } 337 } 338 #endif 339 rv = pmap_enter(fs->map->pmap, vaddr, m_map, prot, fault_type | 340 PMAP_ENTER_NOSLEEP | (wired ? PMAP_ENTER_WIRED : 0), psind); 341 if (rv != KERN_SUCCESS) 342 goto out; 343 if (m_hold != NULL) { 344 *m_hold = m; 345 vm_page_wire(m); 346 } 347 vm_fault_dirty(fs->entry, m, prot, fault_type, fault_flags, false); 348 if (psind == 0 && !wired) 349 vm_fault_prefault(fs, vaddr, PFBAK, PFFOR, true); 350 VM_OBJECT_RUNLOCK(fs->first_object); 351 vm_map_lookup_done(fs->map, fs->entry); 352 curthread->td_ru.ru_minflt++; 353 354 out: 355 vm_object_unbusy(fs->first_object); 356 return (rv); 357 } 358 359 static void 360 vm_fault_restore_map_lock(struct faultstate *fs) 361 { 362 363 VM_OBJECT_ASSERT_WLOCKED(fs->first_object); 364 MPASS(REFCOUNT_COUNT(fs->first_object->paging_in_progress) > 0); 365 366 if (!vm_map_trylock_read(fs->map)) { 367 VM_OBJECT_WUNLOCK(fs->first_object); 368 vm_map_lock_read(fs->map); 369 VM_OBJECT_WLOCK(fs->first_object); 370 } 371 fs->lookup_still_valid = true; 372 } 373 374 static void 375 vm_fault_populate_check_page(vm_page_t m) 376 { 377 378 /* 379 * Check each page to ensure that the pager is obeying the 380 * interface: the page must be installed in the object, fully 381 * valid, and exclusively busied. 382 */ 383 MPASS(m != NULL); 384 MPASS(vm_page_all_valid(m)); 385 MPASS(vm_page_xbusied(m)); 386 } 387 388 static void 389 vm_fault_populate_cleanup(vm_object_t object, vm_pindex_t first, 390 vm_pindex_t last) 391 { 392 vm_page_t m; 393 vm_pindex_t pidx; 394 395 VM_OBJECT_ASSERT_WLOCKED(object); 396 MPASS(first <= last); 397 for (pidx = first, m = vm_page_lookup(object, pidx); 398 pidx <= last; pidx++, m = vm_page_next(m)) { 399 vm_fault_populate_check_page(m); 400 vm_page_lock(m); 401 vm_page_deactivate(m); 402 vm_page_unlock(m); 403 vm_page_xunbusy(m); 404 } 405 } 406 407 static int 408 vm_fault_populate(struct faultstate *fs, vm_prot_t prot, int fault_type, 409 int fault_flags, boolean_t wired, vm_page_t *m_hold) 410 { 411 struct mtx *m_mtx; 412 vm_offset_t vaddr; 413 vm_page_t m; 414 vm_pindex_t map_first, map_last, pager_first, pager_last, pidx; 415 int i, npages, psind, rv; 416 417 MPASS(fs->object == fs->first_object); 418 VM_OBJECT_ASSERT_WLOCKED(fs->first_object); 419 MPASS(REFCOUNT_COUNT(fs->first_object->paging_in_progress) > 0); 420 MPASS(fs->first_object->backing_object == NULL); 421 MPASS(fs->lookup_still_valid); 422 423 pager_first = OFF_TO_IDX(fs->entry->offset); 424 pager_last = pager_first + atop(fs->entry->end - fs->entry->start) - 1; 425 unlock_map(fs); 426 unlock_vp(fs); 427 428 /* 429 * Call the pager (driver) populate() method. 430 * 431 * There is no guarantee that the method will be called again 432 * if the current fault is for read, and a future fault is 433 * for write. Report the entry's maximum allowed protection 434 * to the driver. 435 */ 436 rv = vm_pager_populate(fs->first_object, fs->first_pindex, 437 fault_type, fs->entry->max_protection, &pager_first, &pager_last); 438 439 VM_OBJECT_ASSERT_WLOCKED(fs->first_object); 440 if (rv == VM_PAGER_BAD) { 441 /* 442 * VM_PAGER_BAD is the backdoor for a pager to request 443 * normal fault handling. 444 */ 445 vm_fault_restore_map_lock(fs); 446 if (fs->map->timestamp != fs->map_generation) 447 return (KERN_RESOURCE_SHORTAGE); /* RetryFault */ 448 return (KERN_NOT_RECEIVER); 449 } 450 if (rv != VM_PAGER_OK) 451 return (KERN_FAILURE); /* AKA SIGSEGV */ 452 453 /* Ensure that the driver is obeying the interface. */ 454 MPASS(pager_first <= pager_last); 455 MPASS(fs->first_pindex <= pager_last); 456 MPASS(fs->first_pindex >= pager_first); 457 MPASS(pager_last < fs->first_object->size); 458 459 vm_fault_restore_map_lock(fs); 460 if (fs->map->timestamp != fs->map_generation) { 461 vm_fault_populate_cleanup(fs->first_object, pager_first, 462 pager_last); 463 return (KERN_RESOURCE_SHORTAGE); /* RetryFault */ 464 } 465 466 /* 467 * The map is unchanged after our last unlock. Process the fault. 468 * 469 * The range [pager_first, pager_last] that is given to the 470 * pager is only a hint. The pager may populate any range 471 * within the object that includes the requested page index. 472 * In case the pager expanded the range, clip it to fit into 473 * the map entry. 474 */ 475 map_first = OFF_TO_IDX(fs->entry->offset); 476 if (map_first > pager_first) { 477 vm_fault_populate_cleanup(fs->first_object, pager_first, 478 map_first - 1); 479 pager_first = map_first; 480 } 481 map_last = map_first + atop(fs->entry->end - fs->entry->start) - 1; 482 if (map_last < pager_last) { 483 vm_fault_populate_cleanup(fs->first_object, map_last + 1, 484 pager_last); 485 pager_last = map_last; 486 } 487 for (pidx = pager_first, m = vm_page_lookup(fs->first_object, pidx); 488 pidx <= pager_last; 489 pidx += npages, m = vm_page_next(&m[npages - 1])) { 490 vaddr = fs->entry->start + IDX_TO_OFF(pidx) - fs->entry->offset; 491 #if defined(__aarch64__) || defined(__amd64__) || (defined(__arm__) && \ 492 __ARM_ARCH >= 6) || defined(__i386__) || defined(__riscv) 493 psind = m->psind; 494 if (psind > 0 && ((vaddr & (pagesizes[psind] - 1)) != 0 || 495 pidx + OFF_TO_IDX(pagesizes[psind]) - 1 > pager_last || 496 !pmap_ps_enabled(fs->map->pmap) || wired)) 497 psind = 0; 498 #else 499 psind = 0; 500 #endif 501 npages = atop(pagesizes[psind]); 502 for (i = 0; i < npages; i++) { 503 vm_fault_populate_check_page(&m[i]); 504 vm_fault_dirty(fs->entry, &m[i], prot, fault_type, 505 fault_flags, true); 506 } 507 VM_OBJECT_WUNLOCK(fs->first_object); 508 rv = pmap_enter(fs->map->pmap, vaddr, m, prot, fault_type | 509 (wired ? PMAP_ENTER_WIRED : 0), psind); 510 #if defined(__amd64__) 511 if (psind > 0 && rv == KERN_FAILURE) { 512 for (i = 0; i < npages; i++) { 513 rv = pmap_enter(fs->map->pmap, vaddr + ptoa(i), 514 &m[i], prot, fault_type | 515 (wired ? PMAP_ENTER_WIRED : 0), 0); 516 MPASS(rv == KERN_SUCCESS); 517 } 518 } 519 #else 520 MPASS(rv == KERN_SUCCESS); 521 #endif 522 VM_OBJECT_WLOCK(fs->first_object); 523 m_mtx = NULL; 524 for (i = 0; i < npages; i++) { 525 if ((fault_flags & VM_FAULT_WIRE) != 0) { 526 vm_page_wire(&m[i]); 527 } else { 528 vm_page_change_lock(&m[i], &m_mtx); 529 vm_page_activate(&m[i]); 530 } 531 if (m_hold != NULL && m[i].pindex == fs->first_pindex) { 532 *m_hold = &m[i]; 533 vm_page_wire(&m[i]); 534 } 535 vm_page_xunbusy(&m[i]); 536 } 537 if (m_mtx != NULL) 538 mtx_unlock(m_mtx); 539 } 540 curthread->td_ru.ru_majflt++; 541 return (KERN_SUCCESS); 542 } 543 544 static int prot_fault_translation; 545 SYSCTL_INT(_machdep, OID_AUTO, prot_fault_translation, CTLFLAG_RWTUN, 546 &prot_fault_translation, 0, 547 "Control signal to deliver on protection fault"); 548 549 /* compat definition to keep common code for signal translation */ 550 #define UCODE_PAGEFLT 12 551 #ifdef T_PAGEFLT 552 _Static_assert(UCODE_PAGEFLT == T_PAGEFLT, "T_PAGEFLT"); 553 #endif 554 555 /* 556 * vm_fault_trap: 557 * 558 * Handle a page fault occurring at the given address, 559 * requiring the given permissions, in the map specified. 560 * If successful, the page is inserted into the 561 * associated physical map. 562 * 563 * NOTE: the given address should be truncated to the 564 * proper page address. 565 * 566 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 567 * a standard error specifying why the fault is fatal is returned. 568 * 569 * The map in question must be referenced, and remains so. 570 * Caller may hold no locks. 571 */ 572 int 573 vm_fault_trap(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 574 int fault_flags, int *signo, int *ucode) 575 { 576 int result; 577 578 MPASS(signo == NULL || ucode != NULL); 579 #ifdef KTRACE 580 if (map != kernel_map && KTRPOINT(curthread, KTR_FAULT)) 581 ktrfault(vaddr, fault_type); 582 #endif 583 result = vm_fault(map, trunc_page(vaddr), fault_type, fault_flags, 584 NULL); 585 KASSERT(result == KERN_SUCCESS || result == KERN_FAILURE || 586 result == KERN_INVALID_ADDRESS || 587 result == KERN_RESOURCE_SHORTAGE || 588 result == KERN_PROTECTION_FAILURE || 589 result == KERN_OUT_OF_BOUNDS, 590 ("Unexpected Mach error %d from vm_fault()", result)); 591 #ifdef KTRACE 592 if (map != kernel_map && KTRPOINT(curthread, KTR_FAULTEND)) 593 ktrfaultend(result); 594 #endif 595 if (result != KERN_SUCCESS && signo != NULL) { 596 switch (result) { 597 case KERN_FAILURE: 598 case KERN_INVALID_ADDRESS: 599 *signo = SIGSEGV; 600 *ucode = SEGV_MAPERR; 601 break; 602 case KERN_RESOURCE_SHORTAGE: 603 *signo = SIGBUS; 604 *ucode = BUS_OOMERR; 605 break; 606 case KERN_OUT_OF_BOUNDS: 607 *signo = SIGBUS; 608 *ucode = BUS_OBJERR; 609 break; 610 case KERN_PROTECTION_FAILURE: 611 if (prot_fault_translation == 0) { 612 /* 613 * Autodetect. This check also covers 614 * the images without the ABI-tag ELF 615 * note. 616 */ 617 if (SV_CURPROC_ABI() == SV_ABI_FREEBSD && 618 curproc->p_osrel >= P_OSREL_SIGSEGV) { 619 *signo = SIGSEGV; 620 *ucode = SEGV_ACCERR; 621 } else { 622 *signo = SIGBUS; 623 *ucode = UCODE_PAGEFLT; 624 } 625 } else if (prot_fault_translation == 1) { 626 /* Always compat mode. */ 627 *signo = SIGBUS; 628 *ucode = UCODE_PAGEFLT; 629 } else { 630 /* Always SIGSEGV mode. */ 631 *signo = SIGSEGV; 632 *ucode = SEGV_ACCERR; 633 } 634 break; 635 default: 636 KASSERT(0, ("Unexpected Mach error %d from vm_fault()", 637 result)); 638 break; 639 } 640 } 641 return (result); 642 } 643 644 static int 645 vm_fault_lock_vnode(struct faultstate *fs) 646 { 647 struct vnode *vp; 648 int error, locked; 649 650 if (fs->object->type != OBJT_VNODE) 651 return (KERN_SUCCESS); 652 vp = fs->object->handle; 653 if (vp == fs->vp) { 654 ASSERT_VOP_LOCKED(vp, "saved vnode is not locked"); 655 return (KERN_SUCCESS); 656 } 657 658 /* 659 * Perform an unlock in case the desired vnode changed while 660 * the map was unlocked during a retry. 661 */ 662 unlock_vp(fs); 663 664 locked = VOP_ISLOCKED(vp); 665 if (locked != LK_EXCLUSIVE) 666 locked = LK_SHARED; 667 668 /* 669 * We must not sleep acquiring the vnode lock while we have 670 * the page exclusive busied or the object's 671 * paging-in-progress count incremented. Otherwise, we could 672 * deadlock. 673 */ 674 error = vget(vp, locked | LK_CANRECURSE | LK_NOWAIT, curthread); 675 if (error == 0) { 676 fs->vp = vp; 677 return (KERN_SUCCESS); 678 } 679 680 vhold(vp); 681 release_page(fs); 682 unlock_and_deallocate(fs); 683 error = vget(vp, locked | LK_RETRY | LK_CANRECURSE, curthread); 684 vdrop(vp); 685 fs->vp = vp; 686 KASSERT(error == 0, ("vm_fault: vget failed %d", error)); 687 return (KERN_RESOURCE_SHORTAGE); 688 } 689 690 int 691 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 692 int fault_flags, vm_page_t *m_hold) 693 { 694 struct faultstate fs; 695 struct domainset *dset; 696 vm_object_t next_object, retry_object; 697 vm_offset_t e_end, e_start; 698 vm_pindex_t retry_pindex; 699 vm_prot_t prot, retry_prot; 700 int ahead, alloc_req, behind, cluster_offset, era, faultcount; 701 int nera, oom, result, rv; 702 u_char behavior; 703 boolean_t wired; /* Passed by reference. */ 704 bool dead, hardfault, is_first_object_locked; 705 706 VM_CNT_INC(v_vm_faults); 707 708 if ((curthread->td_pflags & TDP_NOFAULTING) != 0) 709 return (KERN_PROTECTION_FAILURE); 710 711 fs.vp = NULL; 712 faultcount = 0; 713 nera = -1; 714 hardfault = false; 715 716 RetryFault: 717 oom = 0; 718 RetryFault_oom: 719 720 /* 721 * Find the backing store object and offset into it to begin the 722 * search. 723 */ 724 fs.map = map; 725 result = vm_map_lookup(&fs.map, vaddr, fault_type | 726 VM_PROT_FAULT_LOOKUP, &fs.entry, &fs.first_object, 727 &fs.first_pindex, &prot, &wired); 728 if (result != KERN_SUCCESS) { 729 unlock_vp(&fs); 730 return (result); 731 } 732 733 fs.map_generation = fs.map->timestamp; 734 735 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 736 panic("%s: fault on nofault entry, addr: %#lx", 737 __func__, (u_long)vaddr); 738 } 739 740 if (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION && 741 fs.entry->wiring_thread != curthread) { 742 vm_map_unlock_read(fs.map); 743 vm_map_lock(fs.map); 744 if (vm_map_lookup_entry(fs.map, vaddr, &fs.entry) && 745 (fs.entry->eflags & MAP_ENTRY_IN_TRANSITION)) { 746 unlock_vp(&fs); 747 fs.entry->eflags |= MAP_ENTRY_NEEDS_WAKEUP; 748 vm_map_unlock_and_wait(fs.map, 0); 749 } else 750 vm_map_unlock(fs.map); 751 goto RetryFault; 752 } 753 754 MPASS((fs.entry->eflags & MAP_ENTRY_GUARD) == 0); 755 756 if (wired) 757 fault_type = prot | (fault_type & VM_PROT_COPY); 758 else 759 KASSERT((fault_flags & VM_FAULT_WIRE) == 0, 760 ("!wired && VM_FAULT_WIRE")); 761 762 /* 763 * Try to avoid lock contention on the top-level object through 764 * special-case handling of some types of page faults, specifically, 765 * those that are mapping an existing page from the top-level object. 766 * Under this condition, a read lock on the object suffices, allowing 767 * multiple page faults of a similar type to run in parallel. 768 */ 769 if (fs.vp == NULL /* avoid locked vnode leak */ && 770 (fault_flags & (VM_FAULT_WIRE | VM_FAULT_DIRTY)) == 0) { 771 VM_OBJECT_RLOCK(fs.first_object); 772 rv = vm_fault_soft_fast(&fs, vaddr, prot, fault_type, 773 fault_flags, wired, m_hold); 774 if (rv == KERN_SUCCESS) 775 return (rv); 776 if (!VM_OBJECT_TRYUPGRADE(fs.first_object)) { 777 VM_OBJECT_RUNLOCK(fs.first_object); 778 VM_OBJECT_WLOCK(fs.first_object); 779 } 780 } else { 781 VM_OBJECT_WLOCK(fs.first_object); 782 } 783 784 /* 785 * Make a reference to this object to prevent its disposal while we 786 * are messing with it. Once we have the reference, the map is free 787 * to be diddled. Since objects reference their shadows (and copies), 788 * they will stay around as well. 789 * 790 * Bump the paging-in-progress count to prevent size changes (e.g. 791 * truncation operations) during I/O. 792 */ 793 vm_object_reference_locked(fs.first_object); 794 vm_object_pip_add(fs.first_object, 1); 795 796 fs.lookup_still_valid = true; 797 798 fs.first_m = NULL; 799 800 /* 801 * Search for the page at object/offset. 802 */ 803 fs.object = fs.first_object; 804 fs.pindex = fs.first_pindex; 805 while (TRUE) { 806 /* 807 * If the object is marked for imminent termination, 808 * we retry here, since the collapse pass has raced 809 * with us. Otherwise, if we see terminally dead 810 * object, return fail. 811 */ 812 if ((fs.object->flags & OBJ_DEAD) != 0) { 813 dead = fs.object->type == OBJT_DEAD; 814 unlock_and_deallocate(&fs); 815 if (dead) 816 return (KERN_PROTECTION_FAILURE); 817 pause("vmf_de", 1); 818 goto RetryFault; 819 } 820 821 /* 822 * See if page is resident 823 */ 824 fs.m = vm_page_lookup(fs.object, fs.pindex); 825 if (fs.m != NULL) { 826 /* 827 * Wait/Retry if the page is busy. We have to do this 828 * if the page is either exclusive or shared busy 829 * because the vm_pager may be using read busy for 830 * pageouts (and even pageins if it is the vnode 831 * pager), and we could end up trying to pagein and 832 * pageout the same page simultaneously. 833 * 834 * We can theoretically allow the busy case on a read 835 * fault if the page is marked valid, but since such 836 * pages are typically already pmap'd, putting that 837 * special case in might be more effort then it is 838 * worth. We cannot under any circumstances mess 839 * around with a shared busied page except, perhaps, 840 * to pmap it. 841 */ 842 if (vm_page_tryxbusy(fs.m) == 0) { 843 /* 844 * Reference the page before unlocking and 845 * sleeping so that the page daemon is less 846 * likely to reclaim it. 847 */ 848 vm_page_aflag_set(fs.m, PGA_REFERENCED); 849 if (fs.object != fs.first_object) { 850 if (!VM_OBJECT_TRYWLOCK( 851 fs.first_object)) { 852 VM_OBJECT_WUNLOCK(fs.object); 853 VM_OBJECT_WLOCK(fs.first_object); 854 VM_OBJECT_WLOCK(fs.object); 855 } 856 vm_page_free(fs.first_m); 857 vm_object_pip_wakeup(fs.first_object); 858 VM_OBJECT_WUNLOCK(fs.first_object); 859 fs.first_m = NULL; 860 } 861 unlock_map(&fs); 862 if (fs.m == vm_page_lookup(fs.object, 863 fs.pindex)) { 864 vm_page_sleep_if_busy(fs.m, "vmpfw"); 865 } 866 vm_object_pip_wakeup(fs.object); 867 VM_OBJECT_WUNLOCK(fs.object); 868 VM_CNT_INC(v_intrans); 869 vm_object_deallocate(fs.first_object); 870 goto RetryFault; 871 } 872 873 /* 874 * The page is marked busy for other processes and the 875 * pagedaemon. If it still isn't completely valid 876 * (readable), jump to readrest, else break-out ( we 877 * found the page ). 878 */ 879 if (!vm_page_all_valid(fs.m)) 880 goto readrest; 881 break; /* break to PAGE HAS BEEN FOUND */ 882 } 883 KASSERT(fs.m == NULL, ("fs.m should be NULL, not %p", fs.m)); 884 885 /* 886 * Page is not resident. If the pager might contain the page 887 * or this is the beginning of the search, allocate a new 888 * page. (Default objects are zero-fill, so there is no real 889 * pager for them.) 890 */ 891 if (fs.object->type != OBJT_DEFAULT || 892 fs.object == fs.first_object) { 893 if ((fs.object->flags & OBJ_SIZEVNLOCK) != 0) { 894 rv = vm_fault_lock_vnode(&fs); 895 MPASS(rv == KERN_SUCCESS || 896 rv == KERN_RESOURCE_SHORTAGE); 897 if (rv == KERN_RESOURCE_SHORTAGE) 898 goto RetryFault; 899 } 900 if (fs.pindex >= fs.object->size) { 901 unlock_and_deallocate(&fs); 902 return (KERN_OUT_OF_BOUNDS); 903 } 904 905 if (fs.object == fs.first_object && 906 (fs.first_object->flags & OBJ_POPULATE) != 0 && 907 fs.first_object->shadow_count == 0) { 908 rv = vm_fault_populate(&fs, prot, fault_type, 909 fault_flags, wired, m_hold); 910 switch (rv) { 911 case KERN_SUCCESS: 912 case KERN_FAILURE: 913 unlock_and_deallocate(&fs); 914 return (rv); 915 case KERN_RESOURCE_SHORTAGE: 916 unlock_and_deallocate(&fs); 917 goto RetryFault; 918 case KERN_NOT_RECEIVER: 919 /* 920 * Pager's populate() method 921 * returned VM_PAGER_BAD. 922 */ 923 break; 924 default: 925 panic("inconsistent return codes"); 926 } 927 } 928 929 /* 930 * Allocate a new page for this object/offset pair. 931 * 932 * Unlocked read of the p_flag is harmless. At 933 * worst, the P_KILLED might be not observed 934 * there, and allocation can fail, causing 935 * restart and new reading of the p_flag. 936 */ 937 dset = fs.object->domain.dr_policy; 938 if (dset == NULL) 939 dset = curthread->td_domain.dr_policy; 940 if (!vm_page_count_severe_set(&dset->ds_mask) || 941 P_KILLED(curproc)) { 942 #if VM_NRESERVLEVEL > 0 943 vm_object_color(fs.object, atop(vaddr) - 944 fs.pindex); 945 #endif 946 alloc_req = P_KILLED(curproc) ? 947 VM_ALLOC_SYSTEM : VM_ALLOC_NORMAL; 948 if (fs.object->type != OBJT_VNODE && 949 fs.object->backing_object == NULL) 950 alloc_req |= VM_ALLOC_ZERO; 951 fs.m = vm_page_alloc(fs.object, fs.pindex, 952 alloc_req); 953 } 954 if (fs.m == NULL) { 955 unlock_and_deallocate(&fs); 956 if (vm_pfault_oom_attempts < 0 || 957 oom < vm_pfault_oom_attempts) { 958 oom++; 959 vm_waitpfault(dset, 960 vm_pfault_oom_wait * hz); 961 goto RetryFault_oom; 962 } 963 if (bootverbose) 964 printf( 965 "proc %d (%s) failed to alloc page on fault, starting OOM\n", 966 curproc->p_pid, curproc->p_comm); 967 vm_pageout_oom(VM_OOM_MEM_PF); 968 goto RetryFault; 969 } 970 } 971 972 readrest: 973 /* 974 * At this point, we have either allocated a new page or found 975 * an existing page that is only partially valid. 976 * 977 * We hold a reference on the current object and the page is 978 * exclusive busied. 979 */ 980 981 /* 982 * If the pager for the current object might have the page, 983 * then determine the number of additional pages to read and 984 * potentially reprioritize previously read pages for earlier 985 * reclamation. These operations should only be performed 986 * once per page fault. Even if the current pager doesn't 987 * have the page, the number of additional pages to read will 988 * apply to subsequent objects in the shadow chain. 989 */ 990 if (fs.object->type != OBJT_DEFAULT && nera == -1 && 991 !P_KILLED(curproc)) { 992 KASSERT(fs.lookup_still_valid, ("map unlocked")); 993 era = fs.entry->read_ahead; 994 behavior = vm_map_entry_behavior(fs.entry); 995 if (behavior == MAP_ENTRY_BEHAV_RANDOM) { 996 nera = 0; 997 } else if (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL) { 998 nera = VM_FAULT_READ_AHEAD_MAX; 999 if (vaddr == fs.entry->next_read) 1000 vm_fault_dontneed(&fs, vaddr, nera); 1001 } else if (vaddr == fs.entry->next_read) { 1002 /* 1003 * This is a sequential fault. Arithmetically 1004 * increase the requested number of pages in 1005 * the read-ahead window. The requested 1006 * number of pages is "# of sequential faults 1007 * x (read ahead min + 1) + read ahead min" 1008 */ 1009 nera = VM_FAULT_READ_AHEAD_MIN; 1010 if (era > 0) { 1011 nera += era + 1; 1012 if (nera > VM_FAULT_READ_AHEAD_MAX) 1013 nera = VM_FAULT_READ_AHEAD_MAX; 1014 } 1015 if (era == VM_FAULT_READ_AHEAD_MAX) 1016 vm_fault_dontneed(&fs, vaddr, nera); 1017 } else { 1018 /* 1019 * This is a non-sequential fault. 1020 */ 1021 nera = 0; 1022 } 1023 if (era != nera) { 1024 /* 1025 * A read lock on the map suffices to update 1026 * the read ahead count safely. 1027 */ 1028 fs.entry->read_ahead = nera; 1029 } 1030 1031 /* 1032 * Prepare for unlocking the map. Save the map 1033 * entry's start and end addresses, which are used to 1034 * optimize the size of the pager operation below. 1035 * Even if the map entry's addresses change after 1036 * unlocking the map, using the saved addresses is 1037 * safe. 1038 */ 1039 e_start = fs.entry->start; 1040 e_end = fs.entry->end; 1041 } 1042 1043 /* 1044 * Call the pager to retrieve the page if there is a chance 1045 * that the pager has it, and potentially retrieve additional 1046 * pages at the same time. 1047 */ 1048 if (fs.object->type != OBJT_DEFAULT) { 1049 /* 1050 * Release the map lock before locking the vnode or 1051 * sleeping in the pager. (If the current object has 1052 * a shadow, then an earlier iteration of this loop 1053 * may have already unlocked the map.) 1054 */ 1055 unlock_map(&fs); 1056 1057 rv = vm_fault_lock_vnode(&fs); 1058 MPASS(rv == KERN_SUCCESS || 1059 rv == KERN_RESOURCE_SHORTAGE); 1060 if (rv == KERN_RESOURCE_SHORTAGE) 1061 goto RetryFault; 1062 KASSERT(fs.vp == NULL || !fs.map->system_map, 1063 ("vm_fault: vnode-backed object mapped by system map")); 1064 1065 /* 1066 * Page in the requested page and hint the pager, 1067 * that it may bring up surrounding pages. 1068 */ 1069 if (nera == -1 || behavior == MAP_ENTRY_BEHAV_RANDOM || 1070 P_KILLED(curproc)) { 1071 behind = 0; 1072 ahead = 0; 1073 } else { 1074 /* Is this a sequential fault? */ 1075 if (nera > 0) { 1076 behind = 0; 1077 ahead = nera; 1078 } else { 1079 /* 1080 * Request a cluster of pages that is 1081 * aligned to a VM_FAULT_READ_DEFAULT 1082 * page offset boundary within the 1083 * object. Alignment to a page offset 1084 * boundary is more likely to coincide 1085 * with the underlying file system 1086 * block than alignment to a virtual 1087 * address boundary. 1088 */ 1089 cluster_offset = fs.pindex % 1090 VM_FAULT_READ_DEFAULT; 1091 behind = ulmin(cluster_offset, 1092 atop(vaddr - e_start)); 1093 ahead = VM_FAULT_READ_DEFAULT - 1 - 1094 cluster_offset; 1095 } 1096 ahead = ulmin(ahead, atop(e_end - vaddr) - 1); 1097 } 1098 rv = vm_pager_get_pages(fs.object, &fs.m, 1, 1099 &behind, &ahead); 1100 if (rv == VM_PAGER_OK) { 1101 faultcount = behind + 1 + ahead; 1102 hardfault = true; 1103 break; /* break to PAGE HAS BEEN FOUND */ 1104 } 1105 if (rv == VM_PAGER_ERROR) 1106 printf("vm_fault: pager read error, pid %d (%s)\n", 1107 curproc->p_pid, curproc->p_comm); 1108 1109 /* 1110 * If an I/O error occurred or the requested page was 1111 * outside the range of the pager, clean up and return 1112 * an error. 1113 */ 1114 if (rv == VM_PAGER_ERROR || rv == VM_PAGER_BAD) { 1115 if (!vm_page_wired(fs.m)) 1116 vm_page_free(fs.m); 1117 else 1118 vm_page_xunbusy(fs.m); 1119 fs.m = NULL; 1120 unlock_and_deallocate(&fs); 1121 return (KERN_OUT_OF_BOUNDS); 1122 } 1123 1124 /* 1125 * The requested page does not exist at this object/ 1126 * offset. Remove the invalid page from the object, 1127 * waking up anyone waiting for it, and continue on to 1128 * the next object. However, if this is the top-level 1129 * object, we must leave the busy page in place to 1130 * prevent another process from rushing past us, and 1131 * inserting the page in that object at the same time 1132 * that we are. 1133 */ 1134 if (fs.object != fs.first_object) { 1135 if (!vm_page_wired(fs.m)) 1136 vm_page_free(fs.m); 1137 else 1138 vm_page_xunbusy(fs.m); 1139 fs.m = NULL; 1140 } 1141 } 1142 1143 /* 1144 * We get here if the object has default pager (or unwiring) 1145 * or the pager doesn't have the page. 1146 */ 1147 if (fs.object == fs.first_object) 1148 fs.first_m = fs.m; 1149 1150 /* 1151 * Move on to the next object. Lock the next object before 1152 * unlocking the current one. 1153 */ 1154 next_object = fs.object->backing_object; 1155 if (next_object == NULL) { 1156 /* 1157 * If there's no object left, fill the page in the top 1158 * object with zeros. 1159 */ 1160 if (fs.object != fs.first_object) { 1161 vm_object_pip_wakeup(fs.object); 1162 VM_OBJECT_WUNLOCK(fs.object); 1163 1164 fs.object = fs.first_object; 1165 fs.pindex = fs.first_pindex; 1166 fs.m = fs.first_m; 1167 VM_OBJECT_WLOCK(fs.object); 1168 } 1169 fs.first_m = NULL; 1170 1171 /* 1172 * Zero the page if necessary and mark it valid. 1173 */ 1174 if ((fs.m->flags & PG_ZERO) == 0) { 1175 pmap_zero_page(fs.m); 1176 } else { 1177 VM_CNT_INC(v_ozfod); 1178 } 1179 VM_CNT_INC(v_zfod); 1180 vm_page_valid(fs.m); 1181 /* Don't try to prefault neighboring pages. */ 1182 faultcount = 1; 1183 break; /* break to PAGE HAS BEEN FOUND */ 1184 } else { 1185 KASSERT(fs.object != next_object, 1186 ("object loop %p", next_object)); 1187 VM_OBJECT_WLOCK(next_object); 1188 vm_object_pip_add(next_object, 1); 1189 if (fs.object != fs.first_object) 1190 vm_object_pip_wakeup(fs.object); 1191 fs.pindex += 1192 OFF_TO_IDX(fs.object->backing_object_offset); 1193 VM_OBJECT_WUNLOCK(fs.object); 1194 fs.object = next_object; 1195 } 1196 } 1197 1198 vm_page_assert_xbusied(fs.m); 1199 1200 /* 1201 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 1202 * is held.] 1203 */ 1204 1205 /* 1206 * If the page is being written, but isn't already owned by the 1207 * top-level object, we have to copy it into a new page owned by the 1208 * top-level object. 1209 */ 1210 if (fs.object != fs.first_object) { 1211 /* 1212 * We only really need to copy if we want to write it. 1213 */ 1214 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 1215 /* 1216 * This allows pages to be virtually copied from a 1217 * backing_object into the first_object, where the 1218 * backing object has no other refs to it, and cannot 1219 * gain any more refs. Instead of a bcopy, we just 1220 * move the page from the backing object to the 1221 * first object. Note that we must mark the page 1222 * dirty in the first object so that it will go out 1223 * to swap when needed. 1224 */ 1225 is_first_object_locked = false; 1226 if ( 1227 /* 1228 * Only one shadow object 1229 */ 1230 (fs.object->shadow_count == 1) && 1231 /* 1232 * No COW refs, except us 1233 */ 1234 (fs.object->ref_count == 1) && 1235 /* 1236 * No one else can look this object up 1237 */ 1238 (fs.object->handle == NULL) && 1239 /* 1240 * No other ways to look the object up 1241 */ 1242 ((fs.object->flags & OBJ_ANON) != 0) && 1243 (is_first_object_locked = VM_OBJECT_TRYWLOCK(fs.first_object)) && 1244 /* 1245 * We don't chase down the shadow chain 1246 */ 1247 fs.object == fs.first_object->backing_object) { 1248 1249 (void)vm_page_remove(fs.m); 1250 vm_page_replace_checked(fs.m, fs.first_object, 1251 fs.first_pindex, fs.first_m); 1252 vm_page_free(fs.first_m); 1253 vm_page_dirty(fs.m); 1254 #if VM_NRESERVLEVEL > 0 1255 /* 1256 * Rename the reservation. 1257 */ 1258 vm_reserv_rename(fs.m, fs.first_object, 1259 fs.object, OFF_TO_IDX( 1260 fs.first_object->backing_object_offset)); 1261 #endif 1262 VM_OBJECT_WUNLOCK(fs.object); 1263 fs.first_m = fs.m; 1264 fs.m = NULL; 1265 VM_CNT_INC(v_cow_optim); 1266 } else { 1267 VM_OBJECT_WUNLOCK(fs.object); 1268 /* 1269 * Oh, well, lets copy it. 1270 */ 1271 pmap_copy_page(fs.m, fs.first_m); 1272 vm_page_valid(fs.first_m); 1273 if (wired && (fault_flags & 1274 VM_FAULT_WIRE) == 0) { 1275 vm_page_wire(fs.first_m); 1276 vm_page_unwire(fs.m, PQ_INACTIVE); 1277 } 1278 /* 1279 * We no longer need the old page or object. 1280 */ 1281 release_page(&fs); 1282 } 1283 /* 1284 * fs.object != fs.first_object due to above 1285 * conditional 1286 */ 1287 vm_object_pip_wakeup(fs.object); 1288 1289 /* 1290 * We only try to prefault read-only mappings to the 1291 * neighboring pages when this copy-on-write fault is 1292 * a hard fault. In other cases, trying to prefault 1293 * is typically wasted effort. 1294 */ 1295 if (faultcount == 0) 1296 faultcount = 1; 1297 1298 /* 1299 * Only use the new page below... 1300 */ 1301 fs.object = fs.first_object; 1302 fs.pindex = fs.first_pindex; 1303 fs.m = fs.first_m; 1304 if (!is_first_object_locked) 1305 VM_OBJECT_WLOCK(fs.object); 1306 VM_CNT_INC(v_cow_faults); 1307 curthread->td_cow++; 1308 } else { 1309 prot &= ~VM_PROT_WRITE; 1310 } 1311 } 1312 1313 /* 1314 * We must verify that the maps have not changed since our last 1315 * lookup. 1316 */ 1317 if (!fs.lookup_still_valid) { 1318 if (!vm_map_trylock_read(fs.map)) { 1319 release_page(&fs); 1320 unlock_and_deallocate(&fs); 1321 goto RetryFault; 1322 } 1323 fs.lookup_still_valid = true; 1324 if (fs.map->timestamp != fs.map_generation) { 1325 result = vm_map_lookup_locked(&fs.map, vaddr, fault_type, 1326 &fs.entry, &retry_object, &retry_pindex, &retry_prot, &wired); 1327 1328 /* 1329 * If we don't need the page any longer, put it on the inactive 1330 * list (the easiest thing to do here). If no one needs it, 1331 * pageout will grab it eventually. 1332 */ 1333 if (result != KERN_SUCCESS) { 1334 release_page(&fs); 1335 unlock_and_deallocate(&fs); 1336 1337 /* 1338 * If retry of map lookup would have blocked then 1339 * retry fault from start. 1340 */ 1341 if (result == KERN_FAILURE) 1342 goto RetryFault; 1343 return (result); 1344 } 1345 if ((retry_object != fs.first_object) || 1346 (retry_pindex != fs.first_pindex)) { 1347 release_page(&fs); 1348 unlock_and_deallocate(&fs); 1349 goto RetryFault; 1350 } 1351 1352 /* 1353 * Check whether the protection has changed or the object has 1354 * been copied while we left the map unlocked. Changing from 1355 * read to write permission is OK - we leave the page 1356 * write-protected, and catch the write fault. Changing from 1357 * write to read permission means that we can't mark the page 1358 * write-enabled after all. 1359 */ 1360 prot &= retry_prot; 1361 fault_type &= retry_prot; 1362 if (prot == 0) { 1363 release_page(&fs); 1364 unlock_and_deallocate(&fs); 1365 goto RetryFault; 1366 } 1367 1368 /* Reassert because wired may have changed. */ 1369 KASSERT(wired || (fault_flags & VM_FAULT_WIRE) == 0, 1370 ("!wired && VM_FAULT_WIRE")); 1371 } 1372 } 1373 1374 /* 1375 * If the page was filled by a pager, save the virtual address that 1376 * should be faulted on next under a sequential access pattern to the 1377 * map entry. A read lock on the map suffices to update this address 1378 * safely. 1379 */ 1380 if (hardfault) 1381 fs.entry->next_read = vaddr + ptoa(ahead) + PAGE_SIZE; 1382 1383 vm_page_assert_xbusied(fs.m); 1384 vm_fault_dirty(fs.entry, fs.m, prot, fault_type, fault_flags, true); 1385 1386 /* 1387 * Page must be completely valid or it is not fit to 1388 * map into user space. vm_pager_get_pages() ensures this. 1389 */ 1390 KASSERT(vm_page_all_valid(fs.m), 1391 ("vm_fault: page %p partially invalid", fs.m)); 1392 VM_OBJECT_WUNLOCK(fs.object); 1393 1394 /* 1395 * Put this page into the physical map. We had to do the unlock above 1396 * because pmap_enter() may sleep. We don't put the page 1397 * back on the active queue until later so that the pageout daemon 1398 * won't find it (yet). 1399 */ 1400 pmap_enter(fs.map->pmap, vaddr, fs.m, prot, 1401 fault_type | (wired ? PMAP_ENTER_WIRED : 0), 0); 1402 if (faultcount != 1 && (fault_flags & VM_FAULT_WIRE) == 0 && 1403 wired == 0) 1404 vm_fault_prefault(&fs, vaddr, 1405 faultcount > 0 ? behind : PFBAK, 1406 faultcount > 0 ? ahead : PFFOR, false); 1407 1408 /* 1409 * If the page is not wired down, then put it where the pageout daemon 1410 * can find it. 1411 */ 1412 if ((fault_flags & VM_FAULT_WIRE) != 0) { 1413 vm_page_wire(fs.m); 1414 } else { 1415 vm_page_lock(fs.m); 1416 vm_page_activate(fs.m); 1417 vm_page_unlock(fs.m); 1418 } 1419 if (m_hold != NULL) { 1420 *m_hold = fs.m; 1421 vm_page_wire(fs.m); 1422 } 1423 vm_page_xunbusy(fs.m); 1424 1425 /* 1426 * Unlock everything, and return 1427 */ 1428 fault_deallocate(&fs); 1429 if (hardfault) { 1430 VM_CNT_INC(v_io_faults); 1431 curthread->td_ru.ru_majflt++; 1432 #ifdef RACCT 1433 if (racct_enable && fs.object->type == OBJT_VNODE) { 1434 PROC_LOCK(curproc); 1435 if ((fault_type & (VM_PROT_COPY | VM_PROT_WRITE)) != 0) { 1436 racct_add_force(curproc, RACCT_WRITEBPS, 1437 PAGE_SIZE + behind * PAGE_SIZE); 1438 racct_add_force(curproc, RACCT_WRITEIOPS, 1); 1439 } else { 1440 racct_add_force(curproc, RACCT_READBPS, 1441 PAGE_SIZE + ahead * PAGE_SIZE); 1442 racct_add_force(curproc, RACCT_READIOPS, 1); 1443 } 1444 PROC_UNLOCK(curproc); 1445 } 1446 #endif 1447 } else 1448 curthread->td_ru.ru_minflt++; 1449 1450 return (KERN_SUCCESS); 1451 } 1452 1453 /* 1454 * Speed up the reclamation of pages that precede the faulting pindex within 1455 * the first object of the shadow chain. Essentially, perform the equivalent 1456 * to madvise(..., MADV_DONTNEED) on a large cluster of pages that precedes 1457 * the faulting pindex by the cluster size when the pages read by vm_fault() 1458 * cross a cluster-size boundary. The cluster size is the greater of the 1459 * smallest superpage size and VM_FAULT_DONTNEED_MIN. 1460 * 1461 * When "fs->first_object" is a shadow object, the pages in the backing object 1462 * that precede the faulting pindex are deactivated by vm_fault(). So, this 1463 * function must only be concerned with pages in the first object. 1464 */ 1465 static void 1466 vm_fault_dontneed(const struct faultstate *fs, vm_offset_t vaddr, int ahead) 1467 { 1468 vm_map_entry_t entry; 1469 vm_object_t first_object, object; 1470 vm_offset_t end, start; 1471 vm_page_t m, m_next; 1472 vm_pindex_t pend, pstart; 1473 vm_size_t size; 1474 1475 object = fs->object; 1476 VM_OBJECT_ASSERT_WLOCKED(object); 1477 first_object = fs->first_object; 1478 if (first_object != object) { 1479 if (!VM_OBJECT_TRYWLOCK(first_object)) { 1480 VM_OBJECT_WUNLOCK(object); 1481 VM_OBJECT_WLOCK(first_object); 1482 VM_OBJECT_WLOCK(object); 1483 } 1484 } 1485 /* Neither fictitious nor unmanaged pages can be reclaimed. */ 1486 if ((first_object->flags & (OBJ_FICTITIOUS | OBJ_UNMANAGED)) == 0) { 1487 size = VM_FAULT_DONTNEED_MIN; 1488 if (MAXPAGESIZES > 1 && size < pagesizes[1]) 1489 size = pagesizes[1]; 1490 end = rounddown2(vaddr, size); 1491 if (vaddr - end >= size - PAGE_SIZE - ptoa(ahead) && 1492 (entry = fs->entry)->start < end) { 1493 if (end - entry->start < size) 1494 start = entry->start; 1495 else 1496 start = end - size; 1497 pmap_advise(fs->map->pmap, start, end, MADV_DONTNEED); 1498 pstart = OFF_TO_IDX(entry->offset) + atop(start - 1499 entry->start); 1500 m_next = vm_page_find_least(first_object, pstart); 1501 pend = OFF_TO_IDX(entry->offset) + atop(end - 1502 entry->start); 1503 while ((m = m_next) != NULL && m->pindex < pend) { 1504 m_next = TAILQ_NEXT(m, listq); 1505 if (!vm_page_all_valid(m) || 1506 vm_page_busied(m)) 1507 continue; 1508 1509 /* 1510 * Don't clear PGA_REFERENCED, since it would 1511 * likely represent a reference by a different 1512 * process. 1513 * 1514 * Typically, at this point, prefetched pages 1515 * are still in the inactive queue. Only 1516 * pages that triggered page faults are in the 1517 * active queue. 1518 */ 1519 vm_page_lock(m); 1520 if (!vm_page_inactive(m)) 1521 vm_page_deactivate(m); 1522 vm_page_unlock(m); 1523 } 1524 } 1525 } 1526 if (first_object != object) 1527 VM_OBJECT_WUNLOCK(first_object); 1528 } 1529 1530 /* 1531 * vm_fault_prefault provides a quick way of clustering 1532 * pagefaults into a processes address space. It is a "cousin" 1533 * of vm_map_pmap_enter, except it runs at page fault time instead 1534 * of mmap time. 1535 */ 1536 static void 1537 vm_fault_prefault(const struct faultstate *fs, vm_offset_t addra, 1538 int backward, int forward, bool obj_locked) 1539 { 1540 pmap_t pmap; 1541 vm_map_entry_t entry; 1542 vm_object_t backing_object, lobject; 1543 vm_offset_t addr, starta; 1544 vm_pindex_t pindex; 1545 vm_page_t m; 1546 int i; 1547 1548 pmap = fs->map->pmap; 1549 if (pmap != vmspace_pmap(curthread->td_proc->p_vmspace)) 1550 return; 1551 1552 entry = fs->entry; 1553 1554 if (addra < backward * PAGE_SIZE) { 1555 starta = entry->start; 1556 } else { 1557 starta = addra - backward * PAGE_SIZE; 1558 if (starta < entry->start) 1559 starta = entry->start; 1560 } 1561 1562 /* 1563 * Generate the sequence of virtual addresses that are candidates for 1564 * prefaulting in an outward spiral from the faulting virtual address, 1565 * "addra". Specifically, the sequence is "addra - PAGE_SIZE", "addra 1566 * + PAGE_SIZE", "addra - 2 * PAGE_SIZE", "addra + 2 * PAGE_SIZE", ... 1567 * If the candidate address doesn't have a backing physical page, then 1568 * the loop immediately terminates. 1569 */ 1570 for (i = 0; i < 2 * imax(backward, forward); i++) { 1571 addr = addra + ((i >> 1) + 1) * ((i & 1) == 0 ? -PAGE_SIZE : 1572 PAGE_SIZE); 1573 if (addr > addra + forward * PAGE_SIZE) 1574 addr = 0; 1575 1576 if (addr < starta || addr >= entry->end) 1577 continue; 1578 1579 if (!pmap_is_prefaultable(pmap, addr)) 1580 continue; 1581 1582 pindex = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 1583 lobject = entry->object.vm_object; 1584 if (!obj_locked) 1585 VM_OBJECT_RLOCK(lobject); 1586 while ((m = vm_page_lookup(lobject, pindex)) == NULL && 1587 lobject->type == OBJT_DEFAULT && 1588 (backing_object = lobject->backing_object) != NULL) { 1589 KASSERT((lobject->backing_object_offset & PAGE_MASK) == 1590 0, ("vm_fault_prefault: unaligned object offset")); 1591 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 1592 VM_OBJECT_RLOCK(backing_object); 1593 if (!obj_locked || lobject != entry->object.vm_object) 1594 VM_OBJECT_RUNLOCK(lobject); 1595 lobject = backing_object; 1596 } 1597 if (m == NULL) { 1598 if (!obj_locked || lobject != entry->object.vm_object) 1599 VM_OBJECT_RUNLOCK(lobject); 1600 break; 1601 } 1602 if (vm_page_all_valid(m) && 1603 (m->flags & PG_FICTITIOUS) == 0) 1604 pmap_enter_quick(pmap, addr, m, entry->protection); 1605 if (!obj_locked || lobject != entry->object.vm_object) 1606 VM_OBJECT_RUNLOCK(lobject); 1607 } 1608 } 1609 1610 /* 1611 * Hold each of the physical pages that are mapped by the specified range of 1612 * virtual addresses, ["addr", "addr" + "len"), if those mappings are valid 1613 * and allow the specified types of access, "prot". If all of the implied 1614 * pages are successfully held, then the number of held pages is returned 1615 * together with pointers to those pages in the array "ma". However, if any 1616 * of the pages cannot be held, -1 is returned. 1617 */ 1618 int 1619 vm_fault_quick_hold_pages(vm_map_t map, vm_offset_t addr, vm_size_t len, 1620 vm_prot_t prot, vm_page_t *ma, int max_count) 1621 { 1622 vm_offset_t end, va; 1623 vm_page_t *mp; 1624 int count; 1625 boolean_t pmap_failed; 1626 1627 if (len == 0) 1628 return (0); 1629 end = round_page(addr + len); 1630 addr = trunc_page(addr); 1631 1632 /* 1633 * Check for illegal addresses. 1634 */ 1635 if (addr < vm_map_min(map) || addr > end || end > vm_map_max(map)) 1636 return (-1); 1637 1638 if (atop(end - addr) > max_count) 1639 panic("vm_fault_quick_hold_pages: count > max_count"); 1640 count = atop(end - addr); 1641 1642 /* 1643 * Most likely, the physical pages are resident in the pmap, so it is 1644 * faster to try pmap_extract_and_hold() first. 1645 */ 1646 pmap_failed = FALSE; 1647 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) { 1648 *mp = pmap_extract_and_hold(map->pmap, va, prot); 1649 if (*mp == NULL) 1650 pmap_failed = TRUE; 1651 else if ((prot & VM_PROT_WRITE) != 0 && 1652 (*mp)->dirty != VM_PAGE_BITS_ALL) { 1653 /* 1654 * Explicitly dirty the physical page. Otherwise, the 1655 * caller's changes may go unnoticed because they are 1656 * performed through an unmanaged mapping or by a DMA 1657 * operation. 1658 * 1659 * The object lock is not held here. 1660 * See vm_page_clear_dirty_mask(). 1661 */ 1662 vm_page_dirty(*mp); 1663 } 1664 } 1665 if (pmap_failed) { 1666 /* 1667 * One or more pages could not be held by the pmap. Either no 1668 * page was mapped at the specified virtual address or that 1669 * mapping had insufficient permissions. Attempt to fault in 1670 * and hold these pages. 1671 * 1672 * If vm_fault_disable_pagefaults() was called, 1673 * i.e., TDP_NOFAULTING is set, we must not sleep nor 1674 * acquire MD VM locks, which means we must not call 1675 * vm_fault(). Some (out of tree) callers mark 1676 * too wide a code area with vm_fault_disable_pagefaults() 1677 * already, use the VM_PROT_QUICK_NOFAULT flag to request 1678 * the proper behaviour explicitly. 1679 */ 1680 if ((prot & VM_PROT_QUICK_NOFAULT) != 0 && 1681 (curthread->td_pflags & TDP_NOFAULTING) != 0) 1682 goto error; 1683 for (mp = ma, va = addr; va < end; mp++, va += PAGE_SIZE) 1684 if (*mp == NULL && vm_fault(map, va, prot, 1685 VM_FAULT_NORMAL, mp) != KERN_SUCCESS) 1686 goto error; 1687 } 1688 return (count); 1689 error: 1690 for (mp = ma; mp < ma + count; mp++) 1691 if (*mp != NULL) 1692 vm_page_unwire(*mp, PQ_INACTIVE); 1693 return (-1); 1694 } 1695 1696 /* 1697 * Routine: 1698 * vm_fault_copy_entry 1699 * Function: 1700 * Create new shadow object backing dst_entry with private copy of 1701 * all underlying pages. When src_entry is equal to dst_entry, 1702 * function implements COW for wired-down map entry. Otherwise, 1703 * it forks wired entry into dst_map. 1704 * 1705 * In/out conditions: 1706 * The source and destination maps must be locked for write. 1707 * The source map entry must be wired down (or be a sharing map 1708 * entry corresponding to a main map entry that is wired down). 1709 */ 1710 void 1711 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1712 vm_map_entry_t dst_entry, vm_map_entry_t src_entry, 1713 vm_ooffset_t *fork_charge) 1714 { 1715 vm_object_t backing_object, dst_object, object, src_object; 1716 vm_pindex_t dst_pindex, pindex, src_pindex; 1717 vm_prot_t access, prot; 1718 vm_offset_t vaddr; 1719 vm_page_t dst_m; 1720 vm_page_t src_m; 1721 boolean_t upgrade; 1722 1723 #ifdef lint 1724 src_map++; 1725 #endif /* lint */ 1726 1727 upgrade = src_entry == dst_entry; 1728 access = prot = dst_entry->protection; 1729 1730 src_object = src_entry->object.vm_object; 1731 src_pindex = OFF_TO_IDX(src_entry->offset); 1732 1733 if (upgrade && (dst_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) { 1734 dst_object = src_object; 1735 vm_object_reference(dst_object); 1736 } else { 1737 /* 1738 * Create the top-level object for the destination entry. 1739 * Doesn't actually shadow anything - we copy the pages 1740 * directly. 1741 */ 1742 dst_object = vm_object_allocate_anon(atop(dst_entry->end - 1743 dst_entry->start), NULL, NULL, 0); 1744 #if VM_NRESERVLEVEL > 0 1745 dst_object->flags |= OBJ_COLORED; 1746 dst_object->pg_color = atop(dst_entry->start); 1747 #endif 1748 dst_object->domain = src_object->domain; 1749 dst_object->charge = dst_entry->end - dst_entry->start; 1750 } 1751 1752 VM_OBJECT_WLOCK(dst_object); 1753 KASSERT(upgrade || dst_entry->object.vm_object == NULL, 1754 ("vm_fault_copy_entry: vm_object not NULL")); 1755 if (src_object != dst_object) { 1756 dst_entry->object.vm_object = dst_object; 1757 dst_entry->offset = 0; 1758 dst_entry->eflags &= ~MAP_ENTRY_VN_EXEC; 1759 } 1760 if (fork_charge != NULL) { 1761 KASSERT(dst_entry->cred == NULL, 1762 ("vm_fault_copy_entry: leaked swp charge")); 1763 dst_object->cred = curthread->td_ucred; 1764 crhold(dst_object->cred); 1765 *fork_charge += dst_object->charge; 1766 } else if ((dst_object->type == OBJT_DEFAULT || 1767 dst_object->type == OBJT_SWAP) && 1768 dst_object->cred == NULL) { 1769 KASSERT(dst_entry->cred != NULL, ("no cred for entry %p", 1770 dst_entry)); 1771 dst_object->cred = dst_entry->cred; 1772 dst_entry->cred = NULL; 1773 } 1774 1775 /* 1776 * If not an upgrade, then enter the mappings in the pmap as 1777 * read and/or execute accesses. Otherwise, enter them as 1778 * write accesses. 1779 * 1780 * A writeable large page mapping is only created if all of 1781 * the constituent small page mappings are modified. Marking 1782 * PTEs as modified on inception allows promotion to happen 1783 * without taking potentially large number of soft faults. 1784 */ 1785 if (!upgrade) 1786 access &= ~VM_PROT_WRITE; 1787 1788 /* 1789 * Loop through all of the virtual pages within the entry's 1790 * range, copying each page from the source object to the 1791 * destination object. Since the source is wired, those pages 1792 * must exist. In contrast, the destination is pageable. 1793 * Since the destination object doesn't share any backing storage 1794 * with the source object, all of its pages must be dirtied, 1795 * regardless of whether they can be written. 1796 */ 1797 for (vaddr = dst_entry->start, dst_pindex = 0; 1798 vaddr < dst_entry->end; 1799 vaddr += PAGE_SIZE, dst_pindex++) { 1800 again: 1801 /* 1802 * Find the page in the source object, and copy it in. 1803 * Because the source is wired down, the page will be 1804 * in memory. 1805 */ 1806 if (src_object != dst_object) 1807 VM_OBJECT_RLOCK(src_object); 1808 object = src_object; 1809 pindex = src_pindex + dst_pindex; 1810 while ((src_m = vm_page_lookup(object, pindex)) == NULL && 1811 (backing_object = object->backing_object) != NULL) { 1812 /* 1813 * Unless the source mapping is read-only or 1814 * it is presently being upgraded from 1815 * read-only, the first object in the shadow 1816 * chain should provide all of the pages. In 1817 * other words, this loop body should never be 1818 * executed when the source mapping is already 1819 * read/write. 1820 */ 1821 KASSERT((src_entry->protection & VM_PROT_WRITE) == 0 || 1822 upgrade, 1823 ("vm_fault_copy_entry: main object missing page")); 1824 1825 VM_OBJECT_RLOCK(backing_object); 1826 pindex += OFF_TO_IDX(object->backing_object_offset); 1827 if (object != dst_object) 1828 VM_OBJECT_RUNLOCK(object); 1829 object = backing_object; 1830 } 1831 KASSERT(src_m != NULL, ("vm_fault_copy_entry: page missing")); 1832 1833 if (object != dst_object) { 1834 /* 1835 * Allocate a page in the destination object. 1836 */ 1837 dst_m = vm_page_alloc(dst_object, (src_object == 1838 dst_object ? src_pindex : 0) + dst_pindex, 1839 VM_ALLOC_NORMAL); 1840 if (dst_m == NULL) { 1841 VM_OBJECT_WUNLOCK(dst_object); 1842 VM_OBJECT_RUNLOCK(object); 1843 vm_wait(dst_object); 1844 VM_OBJECT_WLOCK(dst_object); 1845 goto again; 1846 } 1847 pmap_copy_page(src_m, dst_m); 1848 VM_OBJECT_RUNLOCK(object); 1849 dst_m->dirty = dst_m->valid = src_m->valid; 1850 } else { 1851 dst_m = src_m; 1852 if (vm_page_busy_acquire(dst_m, VM_ALLOC_WAITFAIL) == 0) 1853 goto again; 1854 if (dst_m->pindex >= dst_object->size) { 1855 /* 1856 * We are upgrading. Index can occur 1857 * out of bounds if the object type is 1858 * vnode and the file was truncated. 1859 */ 1860 vm_page_xunbusy(dst_m); 1861 break; 1862 } 1863 } 1864 VM_OBJECT_WUNLOCK(dst_object); 1865 1866 /* 1867 * Enter it in the pmap. If a wired, copy-on-write 1868 * mapping is being replaced by a write-enabled 1869 * mapping, then wire that new mapping. 1870 * 1871 * The page can be invalid if the user called 1872 * msync(MS_INVALIDATE) or truncated the backing vnode 1873 * or shared memory object. In this case, do not 1874 * insert it into pmap, but still do the copy so that 1875 * all copies of the wired map entry have similar 1876 * backing pages. 1877 */ 1878 if (vm_page_all_valid(dst_m)) { 1879 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, 1880 access | (upgrade ? PMAP_ENTER_WIRED : 0), 0); 1881 } 1882 1883 /* 1884 * Mark it no longer busy, and put it on the active list. 1885 */ 1886 VM_OBJECT_WLOCK(dst_object); 1887 1888 if (upgrade) { 1889 if (src_m != dst_m) { 1890 vm_page_unwire(src_m, PQ_INACTIVE); 1891 vm_page_wire(dst_m); 1892 } else { 1893 KASSERT(vm_page_wired(dst_m), 1894 ("dst_m %p is not wired", dst_m)); 1895 } 1896 } else { 1897 vm_page_lock(dst_m); 1898 vm_page_activate(dst_m); 1899 vm_page_unlock(dst_m); 1900 } 1901 vm_page_xunbusy(dst_m); 1902 } 1903 VM_OBJECT_WUNLOCK(dst_object); 1904 if (upgrade) { 1905 dst_entry->eflags &= ~(MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY); 1906 vm_object_deallocate(src_object); 1907 } 1908 } 1909 1910 /* 1911 * Block entry into the machine-independent layer's page fault handler by 1912 * the calling thread. Subsequent calls to vm_fault() by that thread will 1913 * return KERN_PROTECTION_FAILURE. Enable machine-dependent handling of 1914 * spurious page faults. 1915 */ 1916 int 1917 vm_fault_disable_pagefaults(void) 1918 { 1919 1920 return (curthread_pflags_set(TDP_NOFAULTING | TDP_RESETSPUR)); 1921 } 1922 1923 void 1924 vm_fault_enable_pagefaults(int save) 1925 { 1926 1927 curthread_pflags_restore(save); 1928 } 1929