1 /* 2 * Copyright (c) 2003-2019 The DragonFly Project. All rights reserved. 3 * 4 * This code is derived from software contributed to The DragonFly Project 5 * by Matthew Dillon <dillon@backplane.com> 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in 15 * the documentation and/or other materials provided with the 16 * distribution. 17 * 3. Neither the name of The DragonFly Project nor the names of its 18 * contributors may be used to endorse or promote products derived 19 * from this software without specific, prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING, 27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 * 34 * --- 35 * 36 * Copyright (c) 1991, 1993 37 * The Regents of the University of California. All rights reserved. 38 * Copyright (c) 1994 John S. Dyson 39 * All rights reserved. 40 * Copyright (c) 1994 David Greenman 41 * All rights reserved. 42 * 43 * 44 * This code is derived from software contributed to Berkeley by 45 * The Mach Operating System project at Carnegie-Mellon University. 46 * 47 * Redistribution and use in source and binary forms, with or without 48 * modification, are permitted provided that the following conditions 49 * are met: 50 * 1. Redistributions of source code must retain the above copyright 51 * notice, this list of conditions and the following disclaimer. 52 * 2. Redistributions in binary form must reproduce the above copyright 53 * notice, this list of conditions and the following disclaimer in the 54 * documentation and/or other materials provided with the distribution. 55 * 3. Neither the name of the University nor the names of its contributors 56 * may be used to endorse or promote products derived from this software 57 * without specific prior written permission. 58 * 59 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 62 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 69 * SUCH DAMAGE. 70 * 71 * --- 72 * 73 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 74 * All rights reserved. 75 * 76 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 77 * 78 * Permission to use, copy, modify and distribute this software and 79 * its documentation is hereby granted, provided that both the copyright 80 * notice and this permission notice appear in all copies of the 81 * software, derivative works or modified versions, and any portions 82 * thereof, and that both notices appear in supporting documentation. 83 * 84 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 85 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 86 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 87 * 88 * Carnegie Mellon requests users of this software to return to 89 * 90 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 91 * School of Computer Science 92 * Carnegie Mellon University 93 * Pittsburgh PA 15213-3890 94 * 95 * any improvements or extensions that they make and grant Carnegie the 96 * rights to redistribute these changes. 97 */ 98 99 /* 100 * Page fault handling module. 101 */ 102 103 #include <sys/param.h> 104 #include <sys/systm.h> 105 #include <sys/kernel.h> 106 #include <sys/proc.h> 107 #include <sys/vnode.h> 108 #include <sys/resourcevar.h> 109 #include <sys/vmmeter.h> 110 #include <sys/vkernel.h> 111 #include <sys/lock.h> 112 #include <sys/sysctl.h> 113 114 #include <cpu/lwbuf.h> 115 116 #include <vm/vm.h> 117 #include <vm/vm_param.h> 118 #include <vm/pmap.h> 119 #include <vm/vm_map.h> 120 #include <vm/vm_object.h> 121 #include <vm/vm_page.h> 122 #include <vm/vm_pageout.h> 123 #include <vm/vm_kern.h> 124 #include <vm/vm_pager.h> 125 #include <vm/vnode_pager.h> 126 #include <vm/swap_pager.h> 127 #include <vm/vm_extern.h> 128 129 #include <vm/vm_page2.h> 130 131 struct faultstate { 132 vm_page_t m; 133 vm_map_backing_t ba; 134 vm_prot_t prot; 135 vm_page_t first_m; 136 vm_map_backing_t first_ba; 137 vm_prot_t first_prot; 138 vm_map_t map; 139 vm_map_entry_t entry; 140 int lookup_still_valid; /* 0=inv 1=valid/rel -1=valid/atomic */ 141 int hardfault; 142 int fault_flags; 143 int shared; 144 int msoftonly; 145 int first_shared; 146 int wflags; 147 int first_ba_held; /* 0=unlocked 1=locked/rel -1=lock/atomic */ 148 struct vnode *vp; 149 }; 150 151 __read_mostly static int debug_fault = 0; 152 SYSCTL_INT(_vm, OID_AUTO, debug_fault, CTLFLAG_RW, &debug_fault, 0, ""); 153 __read_mostly static int debug_cluster = 0; 154 SYSCTL_INT(_vm, OID_AUTO, debug_cluster, CTLFLAG_RW, &debug_cluster, 0, ""); 155 #if 0 156 static int virtual_copy_enable = 1; 157 SYSCTL_INT(_vm, OID_AUTO, virtual_copy_enable, CTLFLAG_RW, 158 &virtual_copy_enable, 0, ""); 159 #endif 160 __read_mostly int vm_shared_fault = 1; 161 TUNABLE_INT("vm.shared_fault", &vm_shared_fault); 162 SYSCTL_INT(_vm, OID_AUTO, shared_fault, CTLFLAG_RW, 163 &vm_shared_fault, 0, "Allow shared token on vm_object"); 164 __read_mostly static int vm_fault_quick_enable = 1; 165 TUNABLE_INT("vm.fault_quick", &vm_fault_quick_enable); 166 SYSCTL_INT(_vm, OID_AUTO, fault_quick, CTLFLAG_RW, 167 &vm_fault_quick_enable, 0, "Allow fast vm_fault shortcut"); 168 169 /* 170 * Define here for debugging ioctls. Note that these are globals, so 171 * they were cause a ton of cache line bouncing. Only use for debugging 172 * purposes. 173 */ 174 /*#define VM_FAULT_QUICK_DEBUG */ 175 #ifdef VM_FAULT_QUICK_DEBUG 176 static long vm_fault_quick_success_count = 0; 177 SYSCTL_LONG(_vm, OID_AUTO, fault_quick_success_count, CTLFLAG_RW, 178 &vm_fault_quick_success_count, 0, ""); 179 static long vm_fault_quick_failure_count1 = 0; 180 SYSCTL_LONG(_vm, OID_AUTO, fault_quick_failure_count1, CTLFLAG_RW, 181 &vm_fault_quick_failure_count1, 0, ""); 182 static long vm_fault_quick_failure_count2 = 0; 183 SYSCTL_LONG(_vm, OID_AUTO, fault_quick_failure_count2, CTLFLAG_RW, 184 &vm_fault_quick_failure_count2, 0, ""); 185 static long vm_fault_quick_failure_count3 = 0; 186 SYSCTL_LONG(_vm, OID_AUTO, fault_quick_failure_count3, CTLFLAG_RW, 187 &vm_fault_quick_failure_count3, 0, ""); 188 static long vm_fault_quick_failure_count4 = 0; 189 SYSCTL_LONG(_vm, OID_AUTO, fault_quick_failure_count4, CTLFLAG_RW, 190 &vm_fault_quick_failure_count4, 0, ""); 191 #endif 192 193 static int vm_fault_quick(struct faultstate *fs, vm_pindex_t first_pindex, 194 vm_prot_t fault_type); 195 static int vm_fault_object(struct faultstate *, vm_pindex_t, vm_prot_t, int); 196 static int vm_fault_vpagetable(struct faultstate *, vm_pindex_t *, 197 vpte_t, int, int); 198 #if 0 199 static int vm_fault_additional_pages (vm_page_t, int, int, vm_page_t *, int *); 200 #endif 201 static void vm_set_nosync(vm_page_t m, vm_map_entry_t entry); 202 static void vm_prefault(pmap_t pmap, vm_offset_t addra, 203 vm_map_entry_t entry, int prot, int fault_flags); 204 static void vm_prefault_quick(pmap_t pmap, vm_offset_t addra, 205 vm_map_entry_t entry, int prot, int fault_flags); 206 207 static __inline void 208 release_page(struct faultstate *fs) 209 { 210 vm_page_deactivate(fs->m); 211 vm_page_wakeup(fs->m); 212 fs->m = NULL; 213 } 214 215 static __inline void 216 unlock_map(struct faultstate *fs) 217 { 218 if (fs->ba != fs->first_ba) 219 vm_object_drop(fs->ba->object); 220 if (fs->first_ba && fs->first_ba_held == 1) { 221 vm_object_drop(fs->first_ba->object); 222 fs->first_ba_held = 0; 223 fs->first_ba = NULL; 224 } 225 fs->ba = NULL; 226 227 /* 228 * NOTE: If lookup_still_valid == -1 the map is assumed to be locked 229 * and caller expects it to remain locked atomically. 230 */ 231 if (fs->lookup_still_valid == 1 && fs->map) { 232 vm_map_lookup_done(fs->map, fs->entry, 0); 233 fs->lookup_still_valid = 0; 234 fs->entry = NULL; 235 } 236 } 237 238 /* 239 * Clean up after a successful call to vm_fault_object() so another call 240 * to vm_fault_object() can be made. 241 */ 242 static void 243 cleanup_fault(struct faultstate *fs) 244 { 245 /* 246 * We allocated a junk page for a COW operation that did 247 * not occur, the page must be freed. 248 */ 249 if (fs->ba != fs->first_ba) { 250 KKASSERT(fs->first_shared == 0); 251 252 /* 253 * first_m could be completely valid and we got here 254 * because of a PG_RAM, don't mistakenly free it! 255 */ 256 if ((fs->first_m->valid & VM_PAGE_BITS_ALL) == 257 VM_PAGE_BITS_ALL) { 258 vm_page_wakeup(fs->first_m); 259 } else { 260 vm_page_free(fs->first_m); 261 } 262 vm_object_pip_wakeup(fs->ba->object); 263 fs->first_m = NULL; 264 265 /* 266 * Reset fs->ba (used by vm_fault_vpagetahble() without 267 * calling unlock_map(), so we need a little duplication. 268 */ 269 vm_object_drop(fs->ba->object); 270 fs->ba = fs->first_ba; 271 } 272 } 273 274 static void 275 unlock_things(struct faultstate *fs) 276 { 277 cleanup_fault(fs); 278 unlock_map(fs); 279 if (fs->vp != NULL) { 280 vput(fs->vp); 281 fs->vp = NULL; 282 } 283 } 284 285 #if 0 286 /* 287 * Virtual copy tests. Used by the fault code to determine if a 288 * page can be moved from an orphan vm_object into its shadow 289 * instead of copying its contents. 290 */ 291 static __inline int 292 virtual_copy_test(struct faultstate *fs) 293 { 294 /* 295 * Must be holding exclusive locks 296 */ 297 if (fs->first_shared || fs->shared || virtual_copy_enable == 0) 298 return 0; 299 300 /* 301 * Map, if present, has not changed 302 */ 303 if (fs->map && fs->map_generation != fs->map->timestamp) 304 return 0; 305 306 /* 307 * No refs, except us 308 */ 309 if (fs->ba->object->ref_count != 1) 310 return 0; 311 312 /* 313 * No one else can look this object up 314 */ 315 if (fs->ba->object->handle != NULL) 316 return 0; 317 318 /* 319 * No other ways to look the object up 320 */ 321 if (fs->ba->object->type != OBJT_DEFAULT && 322 fs->ba->object->type != OBJT_SWAP) 323 return 0; 324 325 /* 326 * We don't chase down the shadow chain 327 */ 328 if (fs->ba != fs->first_ba->backing_ba) 329 return 0; 330 331 return 1; 332 } 333 334 static __inline int 335 virtual_copy_ok(struct faultstate *fs) 336 { 337 if (virtual_copy_test(fs)) { 338 /* 339 * Grab the lock and re-test changeable items. 340 */ 341 if (fs->lookup_still_valid == 0 && fs->map) { 342 if (lockmgr(&fs->map->lock, LK_EXCLUSIVE|LK_NOWAIT)) 343 return 0; 344 fs->lookup_still_valid = 1; 345 if (virtual_copy_test(fs)) { 346 fs->map_generation = ++fs->map->timestamp; 347 return 1; 348 } 349 fs->lookup_still_valid = 0; 350 lockmgr(&fs->map->lock, LK_RELEASE); 351 } 352 } 353 return 0; 354 } 355 #endif 356 357 /* 358 * TRYPAGER 359 * 360 * Determine if the pager for the current object *might* contain the page. 361 * 362 * We only need to try the pager if this is not a default object (default 363 * objects are zero-fill and have no real pager), and if we are not taking 364 * a wiring fault or if the FS entry is wired. 365 */ 366 #define TRYPAGER(fs) \ 367 (fs->ba->object->type != OBJT_DEFAULT && \ 368 (((fs->fault_flags & VM_FAULT_WIRE_MASK) == 0) || \ 369 (fs->wflags & FW_WIRED))) 370 371 /* 372 * vm_fault: 373 * 374 * Handle a page fault occuring at the given address, requiring the given 375 * permissions, in the map specified. If successful, the page is inserted 376 * into the associated physical map. 377 * 378 * NOTE: The given address should be truncated to the proper page address. 379 * 380 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 381 * a standard error specifying why the fault is fatal is returned. 382 * 383 * The map in question must be referenced, and remains so. 384 * The caller may hold no locks. 385 * No other requirements. 386 */ 387 int 388 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags) 389 { 390 int result; 391 vm_pindex_t first_pindex; 392 struct faultstate fs; 393 struct lwp *lp; 394 struct proc *p; 395 thread_t td; 396 struct vm_map_ilock ilock; 397 int didilock; 398 int growstack; 399 int retry = 0; 400 int inherit_prot; 401 402 inherit_prot = fault_type & VM_PROT_NOSYNC; 403 fs.hardfault = 0; 404 fs.fault_flags = fault_flags; 405 fs.vp = NULL; 406 fs.shared = vm_shared_fault; 407 fs.first_shared = vm_shared_fault; 408 growstack = 1; 409 410 /* 411 * vm_map interactions 412 */ 413 td = curthread; 414 if ((lp = td->td_lwp) != NULL) 415 lp->lwp_flags |= LWP_PAGING; 416 417 RetryFault: 418 /* 419 * vm_fault_quick() can shortcut us. 420 */ 421 fs.msoftonly = 0; 422 fs.first_ba_held = 0; 423 424 /* 425 * Find the vm_map_entry representing the backing store and resolve 426 * the top level object and page index. This may have the side 427 * effect of executing a copy-on-write on the map entry, 428 * creating a shadow object, or splitting an anonymous entry for 429 * performance, but will not COW any actual VM pages. 430 * 431 * On success fs.map is left read-locked and various other fields 432 * are initialized but not otherwise referenced or locked. 433 * 434 * NOTE! vm_map_lookup will try to upgrade the fault_type to 435 * VM_FAULT_WRITE if the map entry is a virtual page table 436 * and also writable, so we can set the 'A'accessed bit in 437 * the virtual page table entry. 438 */ 439 fs.map = map; 440 result = vm_map_lookup(&fs.map, vaddr, fault_type, 441 &fs.entry, &fs.first_ba, 442 &first_pindex, &fs.first_prot, &fs.wflags); 443 444 /* 445 * If the lookup failed or the map protections are incompatible, 446 * the fault generally fails. 447 * 448 * The failure could be due to TDF_NOFAULT if vm_map_lookup() 449 * tried to do a COW fault. 450 * 451 * If the caller is trying to do a user wiring we have more work 452 * to do. 453 */ 454 if (result != KERN_SUCCESS) { 455 if (result == KERN_FAILURE_NOFAULT) { 456 result = KERN_FAILURE; 457 goto done; 458 } 459 if (result != KERN_PROTECTION_FAILURE || 460 (fs.fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE) 461 { 462 if (result == KERN_INVALID_ADDRESS && growstack && 463 map != &kernel_map && curproc != NULL) { 464 result = vm_map_growstack(map, vaddr); 465 if (result == KERN_SUCCESS) { 466 growstack = 0; 467 ++retry; 468 goto RetryFault; 469 } 470 result = KERN_FAILURE; 471 } 472 goto done; 473 } 474 475 /* 476 * If we are user-wiring a r/w segment, and it is COW, then 477 * we need to do the COW operation. Note that we don't 478 * currently COW RO sections now, because it is NOT desirable 479 * to COW .text. We simply keep .text from ever being COW'ed 480 * and take the heat that one cannot debug wired .text sections. 481 * 482 * XXX Try to allow the above by specifying OVERRIDE_WRITE. 483 */ 484 result = vm_map_lookup(&fs.map, vaddr, 485 VM_PROT_READ|VM_PROT_WRITE| 486 VM_PROT_OVERRIDE_WRITE, 487 &fs.entry, &fs.first_ba, 488 &first_pindex, &fs.first_prot, 489 &fs.wflags); 490 if (result != KERN_SUCCESS) { 491 /* could also be KERN_FAILURE_NOFAULT */ 492 result = KERN_FAILURE; 493 goto done; 494 } 495 496 /* 497 * If we don't COW now, on a user wire, the user will never 498 * be able to write to the mapping. If we don't make this 499 * restriction, the bookkeeping would be nearly impossible. 500 * 501 * XXX We have a shared lock, this will have a MP race but 502 * I don't see how it can hurt anything. 503 */ 504 if ((fs.entry->protection & VM_PROT_WRITE) == 0) { 505 atomic_clear_char(&fs.entry->max_protection, 506 VM_PROT_WRITE); 507 } 508 } 509 510 /* 511 * fs.map is read-locked 512 * 513 * Misc checks. Save the map generation number to detect races. 514 */ 515 fs.lookup_still_valid = 1; 516 fs.first_m = NULL; 517 fs.ba = fs.first_ba; /* so unlock_things() works */ 518 fs.prot = fs.first_prot; /* default (used by uksmap) */ 519 520 if (fs.entry->eflags & (MAP_ENTRY_NOFAULT | MAP_ENTRY_KSTACK)) { 521 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 522 panic("vm_fault: fault on nofault entry, addr: %p", 523 (void *)vaddr); 524 } 525 if ((fs.entry->eflags & MAP_ENTRY_KSTACK) && 526 vaddr >= fs.entry->ba.start && 527 vaddr < fs.entry->ba.start + PAGE_SIZE) { 528 panic("vm_fault: fault on stack guard, addr: %p", 529 (void *)vaddr); 530 } 531 } 532 533 /* 534 * A user-kernel shared map has no VM object and bypasses 535 * everything. We execute the uksmap function with a temporary 536 * fictitious vm_page. The address is directly mapped with no 537 * management. 538 */ 539 if (fs.entry->maptype == VM_MAPTYPE_UKSMAP) { 540 struct vm_page fakem; 541 542 bzero(&fakem, sizeof(fakem)); 543 fakem.pindex = first_pindex; 544 fakem.flags = PG_FICTITIOUS | PG_UNQUEUED; 545 fakem.busy_count = PBUSY_LOCKED; 546 fakem.valid = VM_PAGE_BITS_ALL; 547 fakem.pat_mode = VM_MEMATTR_DEFAULT; 548 if (fs.entry->ba.uksmap(fs.entry->aux.dev, &fakem)) { 549 result = KERN_FAILURE; 550 unlock_things(&fs); 551 goto done2; 552 } 553 pmap_enter(fs.map->pmap, vaddr, &fakem, fs.prot | inherit_prot, 554 (fs.wflags & FW_WIRED), fs.entry); 555 goto done_success; 556 } 557 558 /* 559 * A system map entry may return a NULL object. No object means 560 * no pager means an unrecoverable kernel fault. 561 */ 562 if (fs.first_ba == NULL) { 563 panic("vm_fault: unrecoverable fault at %p in entry %p", 564 (void *)vaddr, fs.entry); 565 } 566 567 /* 568 * Fail here if not a trivial anonymous page fault and TDF_NOFAULT 569 * is set. 570 * 571 * Unfortunately a deadlock can occur if we are forced to page-in 572 * from swap, but diving all the way into the vm_pager_get_page() 573 * function to find out is too much. Just check the object type. 574 * 575 * The deadlock is a CAM deadlock on a busy VM page when trying 576 * to finish an I/O if another process gets stuck in 577 * vop_helper_read_shortcut() due to a swap fault. 578 */ 579 if ((td->td_flags & TDF_NOFAULT) && 580 (retry || 581 fs.first_ba->object->type == OBJT_VNODE || 582 fs.first_ba->object->type == OBJT_SWAP || 583 fs.first_ba->backing_ba)) { 584 result = KERN_FAILURE; 585 unlock_things(&fs); 586 goto done2; 587 } 588 589 /* 590 * If the entry is wired we cannot change the page protection. 591 */ 592 if (fs.wflags & FW_WIRED) 593 fault_type = fs.first_prot; 594 595 /* 596 * We generally want to avoid unnecessary exclusive modes on backing 597 * and terminal objects because this can seriously interfere with 598 * heavily fork()'d processes (particularly /bin/sh scripts). 599 * 600 * However, we also want to avoid unnecessary retries due to needed 601 * shared->exclusive promotion for common faults. Exclusive mode is 602 * always needed if any page insertion, rename, or free occurs in an 603 * object (and also indirectly if any I/O is done). 604 * 605 * The main issue here is going to be fs.first_shared. If the 606 * first_object has a backing object which isn't shadowed and the 607 * process is single-threaded we might as well use an exclusive 608 * lock/chain right off the bat. 609 */ 610 #if 0 611 /* WORK IN PROGRESS, CODE REMOVED */ 612 if (fs.first_shared && fs.first_object->backing_object && 613 LIST_EMPTY(&fs.first_object->shadow_head) && 614 td->td_proc && td->td_proc->p_nthreads == 1) { 615 fs.first_shared = 0; 616 } 617 #endif 618 619 /* 620 * VM_FAULT_UNSWAP - swap_pager_unswapped() needs an exclusive object 621 * VM_FAULT_DIRTY - may require swap_pager_unswapped() later, but 622 * we can try shared first. 623 */ 624 if (fault_flags & VM_FAULT_UNSWAP) 625 fs.first_shared = 0; 626 627 /* 628 * Try to shortcut the entire mess and run the fault lockless. 629 */ 630 if (vm_fault_quick_enable && 631 vm_fault_quick(&fs, first_pindex, fault_type) == KERN_SUCCESS) { 632 didilock = 0; 633 fault_flags &= ~VM_FAULT_BURST; 634 goto success; 635 } 636 637 /* 638 * Exclusive heuristic (alloc page vs page exists) 639 */ 640 if (fs.first_ba->flags & VM_MAP_BACK_EXCL_HEUR) 641 fs.first_shared = 0; 642 643 /* 644 * Obtain a top-level object lock, shared or exclusive depending 645 * on fs.first_shared. If a shared lock winds up being insufficient 646 * we will retry with an exclusive lock. 647 * 648 * The vnode pager lock is always shared. 649 */ 650 if (fs.first_shared) 651 vm_object_hold_shared(fs.first_ba->object); 652 else 653 vm_object_hold(fs.first_ba->object); 654 if (fs.vp == NULL) 655 fs.vp = vnode_pager_lock(fs.first_ba); 656 fs.first_ba_held = 1; 657 658 /* 659 * The page we want is at (first_object, first_pindex), but if the 660 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the 661 * page table to figure out the actual pindex. 662 * 663 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION 664 * ONLY 665 */ 666 didilock = 0; 667 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) { 668 vm_map_interlock(fs.map, &ilock, vaddr, vaddr + PAGE_SIZE); 669 didilock = 1; 670 result = vm_fault_vpagetable(&fs, &first_pindex, 671 fs.entry->aux.master_pde, 672 fault_type, 1); 673 if (result == KERN_TRY_AGAIN) { 674 vm_map_deinterlock(fs.map, &ilock); 675 ++retry; 676 goto RetryFault; 677 } 678 if (result != KERN_SUCCESS) { 679 vm_map_deinterlock(fs.map, &ilock); 680 goto done; 681 } 682 } 683 684 /* 685 * Now we have the actual (object, pindex), fault in the page. If 686 * vm_fault_object() fails it will unlock and deallocate the FS 687 * data. If it succeeds everything remains locked and fs->ba->object 688 * will have an additional PIP count if fs->ba != fs->first_ba. 689 * 690 * vm_fault_object will set fs->prot for the pmap operation. It is 691 * allowed to set VM_PROT_WRITE if fault_type == VM_PROT_READ if the 692 * page can be safely written. However, it will force a read-only 693 * mapping for a read fault if the memory is managed by a virtual 694 * page table. 695 * 696 * If the fault code uses the shared object lock shortcut 697 * we must not try to burst (we can't allocate VM pages). 698 */ 699 result = vm_fault_object(&fs, first_pindex, fault_type, 1); 700 701 if (debug_fault > 0) { 702 --debug_fault; 703 kprintf("VM_FAULT result %d addr=%jx type=%02x flags=%02x " 704 "fs.m=%p fs.prot=%02x fs.wflags=%02x fs.entry=%p\n", 705 result, (intmax_t)vaddr, fault_type, fault_flags, 706 fs.m, fs.prot, fs.wflags, fs.entry); 707 } 708 709 if (result == KERN_TRY_AGAIN) { 710 if (didilock) 711 vm_map_deinterlock(fs.map, &ilock); 712 ++retry; 713 goto RetryFault; 714 } 715 if (result != KERN_SUCCESS) { 716 if (didilock) 717 vm_map_deinterlock(fs.map, &ilock); 718 goto done; 719 } 720 721 success: 722 /* 723 * On success vm_fault_object() does not unlock or deallocate, and fs.m 724 * will contain a busied page. It does drop fs->ba if appropriate. 725 * 726 * Enter the page into the pmap and do pmap-related adjustments. 727 * 728 * WARNING! Soft-busied fs.m's can only be manipulated in limited 729 * ways. 730 */ 731 KKASSERT(fs.lookup_still_valid != 0); 732 vm_page_flag_set(fs.m, PG_REFERENCED); 733 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot | inherit_prot, 734 fs.wflags & FW_WIRED, fs.entry); 735 736 if (didilock) 737 vm_map_deinterlock(fs.map, &ilock); 738 739 /* 740 * If the page is not wired down, then put it where the pageout daemon 741 * can find it. 742 * 743 * NOTE: We cannot safely wire, unwire, or adjust queues for a 744 * soft-busied page. 745 */ 746 if (fs.msoftonly) { 747 KKASSERT(fs.m->busy_count & PBUSY_MASK); 748 KKASSERT((fs.fault_flags & VM_FAULT_WIRE_MASK) == 0); 749 vm_page_sbusy_drop(fs.m); 750 } else { 751 if (fs.fault_flags & VM_FAULT_WIRE_MASK) { 752 if (fs.wflags & FW_WIRED) 753 vm_page_wire(fs.m); 754 else 755 vm_page_unwire(fs.m, 1); 756 } else { 757 vm_page_activate(fs.m); 758 } 759 KKASSERT(fs.m->busy_count & PBUSY_LOCKED); 760 vm_page_wakeup(fs.m); 761 } 762 763 /* 764 * Burst in a few more pages if possible. The fs.map should still 765 * be locked. To avoid interlocking against a vnode->getblk 766 * operation we had to be sure to unbusy our primary vm_page above 767 * first. 768 * 769 * A normal burst can continue down backing store, only execute 770 * if we are holding an exclusive lock, otherwise the exclusive 771 * locks the burst code gets might cause excessive SMP collisions. 772 * 773 * A quick burst can be utilized when there is no backing object 774 * (i.e. a shared file mmap). 775 */ 776 if ((fault_flags & VM_FAULT_BURST) && 777 (fs.fault_flags & VM_FAULT_WIRE_MASK) == 0 && 778 (fs.wflags & FW_WIRED) == 0) { 779 if (fs.first_shared == 0 && fs.shared == 0) { 780 vm_prefault(fs.map->pmap, vaddr, 781 fs.entry, fs.prot, fault_flags); 782 } else { 783 vm_prefault_quick(fs.map->pmap, vaddr, 784 fs.entry, fs.prot, fault_flags); 785 } 786 } 787 788 done_success: 789 mycpu->gd_cnt.v_vm_faults++; 790 if (td->td_lwp) 791 ++td->td_lwp->lwp_ru.ru_minflt; 792 793 /* 794 * Unlock everything, and return 795 */ 796 unlock_things(&fs); 797 798 if (td->td_lwp) { 799 if (fs.hardfault) { 800 td->td_lwp->lwp_ru.ru_majflt++; 801 } else { 802 td->td_lwp->lwp_ru.ru_minflt++; 803 } 804 } 805 806 /*vm_object_deallocate(fs.first_ba->object);*/ 807 /*fs.m = NULL; */ 808 809 result = KERN_SUCCESS; 810 done: 811 if (fs.first_ba && fs.first_ba->object && fs.first_ba_held == 1) { 812 vm_object_drop(fs.first_ba->object); 813 fs.first_ba_held = 0; 814 } 815 done2: 816 if (lp) 817 lp->lwp_flags &= ~LWP_PAGING; 818 819 #if !defined(NO_SWAPPING) 820 /* 821 * Check the process RSS limit and force deactivation and 822 * (asynchronous) paging if necessary. This is a complex operation, 823 * only do it for direct user-mode faults, for now. 824 * 825 * To reduce overhead implement approximately a ~16MB hysteresis. 826 */ 827 p = td->td_proc; 828 if ((fault_flags & VM_FAULT_USERMODE) && lp && 829 p->p_limit && map->pmap && vm_pageout_memuse_mode >= 1 && 830 map != &kernel_map) { 831 vm_pindex_t limit; 832 vm_pindex_t size; 833 834 limit = OFF_TO_IDX(qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 835 p->p_rlimit[RLIMIT_RSS].rlim_max)); 836 size = pmap_resident_tlnw_count(map->pmap); 837 if (limit >= 0 && size > 4096 && size - 4096 >= limit) { 838 vm_pageout_map_deactivate_pages(map, limit); 839 } 840 } 841 #endif 842 843 if (result != KERN_SUCCESS && debug_fault < 0) { 844 kprintf("VM_FAULT %d:%d (%s) result %d " 845 "addr=%jx type=%02x flags=%02x " 846 "fs.m=%p fs.prot=%02x fs.wflags=%02x fs.entry=%p\n", 847 (curthread->td_proc ? curthread->td_proc->p_pid : -1), 848 (curthread->td_lwp ? curthread->td_lwp->lwp_tid : -1), 849 curthread->td_comm, 850 result, 851 (intmax_t)vaddr, fault_type, fault_flags, 852 fs.m, fs.prot, fs.wflags, fs.entry); 853 while (debug_fault < 0 && (debug_fault & 1)) 854 tsleep(&debug_fault, 0, "DEBUG", hz); 855 } 856 857 return (result); 858 } 859 860 /* 861 * Attempt a lockless vm_fault() shortcut. The stars have to align for this 862 * to work. But if it does we can get our page only soft-busied and not 863 * have to touch the vm_object or vnode locks at all. 864 */ 865 static 866 int 867 vm_fault_quick(struct faultstate *fs, vm_pindex_t first_pindex, 868 vm_prot_t fault_type) 869 { 870 vm_page_t m; 871 vm_object_t obj; /* NOT LOCKED */ 872 873 /* 874 * Don't waste time if the object is only being used by one vm_map. 875 */ 876 obj = fs->first_ba->object; 877 if (obj->flags & OBJ_ONEMAPPING) 878 return KERN_FAILURE; 879 880 /* 881 * This will try to wire/unwire a page, which can't be done with 882 * a soft-busied page. 883 */ 884 if (fs->fault_flags & VM_FAULT_WIRE_MASK) 885 return KERN_FAILURE; 886 887 /* 888 * Ick, can't handle this 889 */ 890 if (fs->entry->maptype == VM_MAPTYPE_VPAGETABLE) { 891 #ifdef VM_FAULT_QUICK_DEBUG 892 ++vm_fault_quick_failure_count1; 893 #endif 894 return KERN_FAILURE; 895 } 896 897 /* 898 * Ok, try to get the vm_page quickly via the hash table. The 899 * page will be soft-busied on success (NOT hard-busied). 900 */ 901 m = vm_page_hash_get(obj, first_pindex); 902 if (m == NULL) { 903 #ifdef VM_FAULT_QUICK_DEBUG 904 ++vm_fault_quick_failure_count2; 905 #endif 906 return KERN_FAILURE; 907 } 908 if ((obj->flags & OBJ_DEAD) || 909 m->valid != VM_PAGE_BITS_ALL || 910 m->queue - m->pc == PQ_CACHE || 911 (m->flags & PG_SWAPPED)) { 912 vm_page_sbusy_drop(m); 913 #ifdef VM_FAULT_QUICK_DEBUG 914 ++vm_fault_quick_failure_count3; 915 #endif 916 return KERN_FAILURE; 917 } 918 919 /* 920 * The page is already fully valid, ACTIVE, and is not PG_SWAPPED. 921 * 922 * Don't map the page writable when emulating the dirty bit, a 923 * fault must be taken for proper emulation (vkernel). 924 */ 925 if (curthread->td_lwp && curthread->td_lwp->lwp_vmspace && 926 pmap_emulate_ad_bits(&curthread->td_lwp->lwp_vmspace->vm_pmap)) { 927 if ((fault_type & VM_PROT_WRITE) == 0) 928 fs->prot &= ~VM_PROT_WRITE; 929 } 930 931 /* 932 * If this is a write fault the object and the page must already 933 * be writable. Since we don't hold an object lock and only a 934 * soft-busy on the page, we cannot manipulate the object or 935 * the page state (other than the page queue). 936 */ 937 if (fs->prot & VM_PROT_WRITE) { 938 if ((obj->flags & (OBJ_WRITEABLE | OBJ_MIGHTBEDIRTY)) != 939 (OBJ_WRITEABLE | OBJ_MIGHTBEDIRTY) || 940 m->dirty != VM_PAGE_BITS_ALL) { 941 vm_page_sbusy_drop(m); 942 #ifdef VM_FAULT_QUICK_DEBUG 943 ++vm_fault_quick_failure_count4; 944 #endif 945 return KERN_FAILURE; 946 } 947 vm_set_nosync(m, fs->entry); 948 } 949 950 /* 951 * Even though we are only soft-busied we can still move pages 952 * around in the normal queue(s). The soft-busy prevents the 953 * page from being removed from the object, etc (normal operation). 954 * 955 * However, in this fast path it is excessively important to avoid 956 * any hard locks, so we use a special passive version of activate. 957 */ 958 vm_page_soft_activate(m); 959 fs->m = m; 960 fs->msoftonly = 1; 961 #ifdef VM_FAULT_QUICK_DEBUG 962 ++vm_fault_quick_success_count; 963 #endif 964 965 return KERN_SUCCESS; 966 } 967 968 /* 969 * Fault in the specified virtual address in the current process map, 970 * returning a held VM page or NULL. See vm_fault_page() for more 971 * information. 972 * 973 * No requirements. 974 */ 975 vm_page_t 976 vm_fault_page_quick(vm_offset_t va, vm_prot_t fault_type, 977 int *errorp, int *busyp) 978 { 979 struct lwp *lp = curthread->td_lwp; 980 vm_page_t m; 981 982 m = vm_fault_page(&lp->lwp_vmspace->vm_map, va, 983 fault_type, VM_FAULT_NORMAL, 984 errorp, busyp); 985 return(m); 986 } 987 988 /* 989 * Fault in the specified virtual address in the specified map, doing all 990 * necessary manipulation of the object store and all necessary I/O. Return 991 * a held VM page or NULL, and set *errorp. The related pmap is not 992 * updated. 993 * 994 * If busyp is not NULL then *busyp will be set to TRUE if this routine 995 * decides to return a busied page (aka VM_PROT_WRITE), or FALSE if it 996 * does not (VM_PROT_WRITE not specified or busyp is NULL). If busyp is 997 * NULL the returned page is only held. 998 * 999 * If the caller has no intention of writing to the page's contents, busyp 1000 * can be passed as NULL along with VM_PROT_WRITE to force a COW operation 1001 * without busying the page. 1002 * 1003 * The returned page will also be marked PG_REFERENCED. 1004 * 1005 * If the page cannot be faulted writable and VM_PROT_WRITE was specified, an 1006 * error will be returned. 1007 * 1008 * No requirements. 1009 */ 1010 vm_page_t 1011 vm_fault_page(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 1012 int fault_flags, int *errorp, int *busyp) 1013 { 1014 vm_pindex_t first_pindex; 1015 struct faultstate fs; 1016 int result; 1017 int retry; 1018 int growstack; 1019 int didcow; 1020 vm_prot_t orig_fault_type = fault_type; 1021 1022 retry = 0; 1023 didcow = 0; 1024 fs.hardfault = 0; 1025 fs.fault_flags = fault_flags; 1026 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0); 1027 1028 /* 1029 * Dive the pmap (concurrency possible). If we find the 1030 * appropriate page we can terminate early and quickly. 1031 * 1032 * This works great for normal programs but will always return 1033 * NULL for host lookups of vkernel maps in VMM mode. 1034 * 1035 * NOTE: pmap_fault_page_quick() might not busy the page. If 1036 * VM_PROT_WRITE is set in fault_type and pmap_fault_page_quick() 1037 * returns non-NULL, it will safely dirty the returned vm_page_t 1038 * for us. We cannot safely dirty it here (it might not be 1039 * busy). 1040 */ 1041 fs.m = pmap_fault_page_quick(map->pmap, vaddr, fault_type, busyp); 1042 if (fs.m) { 1043 *errorp = 0; 1044 return(fs.m); 1045 } 1046 1047 /* 1048 * Otherwise take a concurrency hit and do a formal page 1049 * fault. 1050 */ 1051 fs.vp = NULL; 1052 fs.shared = vm_shared_fault; 1053 fs.first_shared = vm_shared_fault; 1054 fs.msoftonly = 0; 1055 growstack = 1; 1056 1057 /* 1058 * VM_FAULT_UNSWAP - swap_pager_unswapped() needs an exclusive object 1059 * VM_FAULT_DIRTY - may require swap_pager_unswapped() later, but 1060 * we can try shared first. 1061 */ 1062 if (fault_flags & VM_FAULT_UNSWAP) { 1063 fs.first_shared = 0; 1064 } 1065 1066 RetryFault: 1067 /* 1068 * Find the vm_map_entry representing the backing store and resolve 1069 * the top level object and page index. This may have the side 1070 * effect of executing a copy-on-write on the map entry and/or 1071 * creating a shadow object, but will not COW any actual VM pages. 1072 * 1073 * On success fs.map is left read-locked and various other fields 1074 * are initialized but not otherwise referenced or locked. 1075 * 1076 * NOTE! vm_map_lookup will upgrade the fault_type to VM_FAULT_WRITE 1077 * if the map entry is a virtual page table and also writable, 1078 * so we can set the 'A'accessed bit in the virtual page table 1079 * entry. 1080 */ 1081 fs.map = map; 1082 fs.first_ba_held = 0; 1083 result = vm_map_lookup(&fs.map, vaddr, fault_type, 1084 &fs.entry, &fs.first_ba, 1085 &first_pindex, &fs.first_prot, &fs.wflags); 1086 1087 if (result != KERN_SUCCESS) { 1088 if (result == KERN_FAILURE_NOFAULT) { 1089 *errorp = KERN_FAILURE; 1090 fs.m = NULL; 1091 goto done; 1092 } 1093 if (result != KERN_PROTECTION_FAILURE || 1094 (fs.fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE) 1095 { 1096 if (result == KERN_INVALID_ADDRESS && growstack && 1097 map != &kernel_map && curproc != NULL) { 1098 result = vm_map_growstack(map, vaddr); 1099 if (result == KERN_SUCCESS) { 1100 growstack = 0; 1101 ++retry; 1102 goto RetryFault; 1103 } 1104 result = KERN_FAILURE; 1105 } 1106 fs.m = NULL; 1107 *errorp = result; 1108 goto done; 1109 } 1110 1111 /* 1112 * If we are user-wiring a r/w segment, and it is COW, then 1113 * we need to do the COW operation. Note that we don't 1114 * currently COW RO sections now, because it is NOT desirable 1115 * to COW .text. We simply keep .text from ever being COW'ed 1116 * and take the heat that one cannot debug wired .text sections. 1117 */ 1118 result = vm_map_lookup(&fs.map, vaddr, 1119 VM_PROT_READ|VM_PROT_WRITE| 1120 VM_PROT_OVERRIDE_WRITE, 1121 &fs.entry, &fs.first_ba, 1122 &first_pindex, &fs.first_prot, 1123 &fs.wflags); 1124 if (result != KERN_SUCCESS) { 1125 /* could also be KERN_FAILURE_NOFAULT */ 1126 *errorp = KERN_FAILURE; 1127 fs.m = NULL; 1128 goto done; 1129 } 1130 1131 /* 1132 * If we don't COW now, on a user wire, the user will never 1133 * be able to write to the mapping. If we don't make this 1134 * restriction, the bookkeeping would be nearly impossible. 1135 * 1136 * XXX We have a shared lock, this will have a MP race but 1137 * I don't see how it can hurt anything. 1138 */ 1139 if ((fs.entry->protection & VM_PROT_WRITE) == 0) { 1140 atomic_clear_char(&fs.entry->max_protection, 1141 VM_PROT_WRITE); 1142 } 1143 } 1144 1145 /* 1146 * fs.map is read-locked 1147 * 1148 * Misc checks. Save the map generation number to detect races. 1149 */ 1150 fs.lookup_still_valid = 1; 1151 fs.first_m = NULL; 1152 fs.ba = fs.first_ba; 1153 1154 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 1155 panic("vm_fault: fault on nofault entry, addr: %lx", 1156 (u_long)vaddr); 1157 } 1158 1159 /* 1160 * A user-kernel shared map has no VM object and bypasses 1161 * everything. We execute the uksmap function with a temporary 1162 * fictitious vm_page. The address is directly mapped with no 1163 * management. 1164 */ 1165 if (fs.entry->maptype == VM_MAPTYPE_UKSMAP) { 1166 struct vm_page fakem; 1167 1168 bzero(&fakem, sizeof(fakem)); 1169 fakem.pindex = first_pindex; 1170 fakem.flags = PG_FICTITIOUS | PG_UNQUEUED; 1171 fakem.busy_count = PBUSY_LOCKED; 1172 fakem.valid = VM_PAGE_BITS_ALL; 1173 fakem.pat_mode = VM_MEMATTR_DEFAULT; 1174 if (fs.entry->ba.uksmap(fs.entry->aux.dev, &fakem)) { 1175 *errorp = KERN_FAILURE; 1176 fs.m = NULL; 1177 unlock_things(&fs); 1178 goto done2; 1179 } 1180 fs.m = PHYS_TO_VM_PAGE(fakem.phys_addr); 1181 vm_page_hold(fs.m); 1182 if (busyp) 1183 *busyp = 0; /* don't need to busy R or W */ 1184 unlock_things(&fs); 1185 *errorp = 0; 1186 goto done; 1187 } 1188 1189 1190 /* 1191 * A system map entry may return a NULL object. No object means 1192 * no pager means an unrecoverable kernel fault. 1193 */ 1194 if (fs.first_ba == NULL) { 1195 panic("vm_fault: unrecoverable fault at %p in entry %p", 1196 (void *)vaddr, fs.entry); 1197 } 1198 1199 /* 1200 * Fail here if not a trivial anonymous page fault and TDF_NOFAULT 1201 * is set. 1202 * 1203 * Unfortunately a deadlock can occur if we are forced to page-in 1204 * from swap, but diving all the way into the vm_pager_get_page() 1205 * function to find out is too much. Just check the object type. 1206 */ 1207 if ((curthread->td_flags & TDF_NOFAULT) && 1208 (retry || 1209 fs.first_ba->object->type == OBJT_VNODE || 1210 fs.first_ba->object->type == OBJT_SWAP || 1211 fs.first_ba->backing_ba)) { 1212 *errorp = KERN_FAILURE; 1213 unlock_things(&fs); 1214 fs.m = NULL; 1215 goto done2; 1216 } 1217 1218 /* 1219 * If the entry is wired we cannot change the page protection. 1220 */ 1221 if (fs.wflags & FW_WIRED) 1222 fault_type = fs.first_prot; 1223 1224 /* 1225 * Make a reference to this object to prevent its disposal while we 1226 * are messing with it. Once we have the reference, the map is free 1227 * to be diddled. Since objects reference their shadows (and copies), 1228 * they will stay around as well. 1229 * 1230 * The reference should also prevent an unexpected collapse of the 1231 * parent that might move pages from the current object into the 1232 * parent unexpectedly, resulting in corruption. 1233 * 1234 * Bump the paging-in-progress count to prevent size changes (e.g. 1235 * truncation operations) during I/O. This must be done after 1236 * obtaining the vnode lock in order to avoid possible deadlocks. 1237 */ 1238 if (fs.first_ba->flags & VM_MAP_BACK_EXCL_HEUR) 1239 fs.first_shared = 0; 1240 1241 if (fs.first_shared) 1242 vm_object_hold_shared(fs.first_ba->object); 1243 else 1244 vm_object_hold(fs.first_ba->object); 1245 fs.first_ba_held = 1; 1246 if (fs.vp == NULL) 1247 fs.vp = vnode_pager_lock(fs.first_ba); /* shared */ 1248 1249 /* 1250 * The page we want is at (first_object, first_pindex), but if the 1251 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the 1252 * page table to figure out the actual pindex. 1253 * 1254 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION 1255 * ONLY 1256 */ 1257 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) { 1258 result = vm_fault_vpagetable(&fs, &first_pindex, 1259 fs.entry->aux.master_pde, 1260 fault_type, 1); 1261 if (result == KERN_TRY_AGAIN) { 1262 ++retry; 1263 goto RetryFault; 1264 } 1265 if (result != KERN_SUCCESS) { 1266 *errorp = result; 1267 fs.m = NULL; 1268 goto done; 1269 } 1270 } 1271 1272 /* 1273 * Now we have the actual (object, pindex), fault in the page. If 1274 * vm_fault_object() fails it will unlock and deallocate the FS 1275 * data. If it succeeds everything remains locked and fs->ba->object 1276 * will have an additinal PIP count if fs->ba != fs->first_ba. 1277 */ 1278 fs.m = NULL; 1279 result = vm_fault_object(&fs, first_pindex, fault_type, 1); 1280 1281 if (result == KERN_TRY_AGAIN) { 1282 KKASSERT(fs.first_ba_held == 0); 1283 ++retry; 1284 didcow |= fs.wflags & FW_DIDCOW; 1285 goto RetryFault; 1286 } 1287 if (result != KERN_SUCCESS) { 1288 *errorp = result; 1289 fs.m = NULL; 1290 goto done; 1291 } 1292 1293 if ((orig_fault_type & VM_PROT_WRITE) && 1294 (fs.prot & VM_PROT_WRITE) == 0) { 1295 *errorp = KERN_PROTECTION_FAILURE; 1296 unlock_things(&fs); 1297 fs.m = NULL; 1298 goto done; 1299 } 1300 1301 /* 1302 * Generally speaking we don't want to update the pmap because 1303 * this routine can be called many times for situations that do 1304 * not require updating the pmap, not to mention the page might 1305 * already be in the pmap. 1306 * 1307 * However, if our vm_map_lookup() results in a COW, we need to 1308 * at least remove the pte from the pmap to guarantee proper 1309 * visibility of modifications made to the process. For example, 1310 * modifications made by vkernel uiocopy/related routines and 1311 * modifications made by ptrace(). 1312 */ 1313 vm_page_flag_set(fs.m, PG_REFERENCED); 1314 #if 0 1315 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, 1316 fs.wflags & FW_WIRED, NULL); 1317 mycpu->gd_cnt.v_vm_faults++; 1318 if (curthread->td_lwp) 1319 ++curthread->td_lwp->lwp_ru.ru_minflt; 1320 #endif 1321 if ((fs.wflags | didcow) | FW_DIDCOW) { 1322 pmap_remove(fs.map->pmap, 1323 vaddr & ~PAGE_MASK, 1324 (vaddr & ~PAGE_MASK) + PAGE_SIZE); 1325 } 1326 1327 /* 1328 * On success vm_fault_object() does not unlock or deallocate, and fs.m 1329 * will contain a busied page. So we must unlock here after having 1330 * messed with the pmap. 1331 */ 1332 unlock_things(&fs); 1333 1334 /* 1335 * Return a held page. We are not doing any pmap manipulation so do 1336 * not set PG_MAPPED. However, adjust the page flags according to 1337 * the fault type because the caller may not use a managed pmapping 1338 * (so we don't want to lose the fact that the page will be dirtied 1339 * if a write fault was specified). 1340 */ 1341 if (fault_type & VM_PROT_WRITE) 1342 vm_page_dirty(fs.m); 1343 vm_page_activate(fs.m); 1344 1345 if (curthread->td_lwp) { 1346 if (fs.hardfault) { 1347 curthread->td_lwp->lwp_ru.ru_majflt++; 1348 } else { 1349 curthread->td_lwp->lwp_ru.ru_minflt++; 1350 } 1351 } 1352 1353 /* 1354 * Unlock everything, and return the held or busied page. 1355 */ 1356 if (busyp) { 1357 if (fault_type & VM_PROT_WRITE) { 1358 vm_page_dirty(fs.m); 1359 *busyp = 1; 1360 } else { 1361 *busyp = 0; 1362 vm_page_hold(fs.m); 1363 vm_page_wakeup(fs.m); 1364 } 1365 } else { 1366 vm_page_hold(fs.m); 1367 vm_page_wakeup(fs.m); 1368 } 1369 /*vm_object_deallocate(fs.first_ba->object);*/ 1370 *errorp = 0; 1371 1372 done: 1373 KKASSERT(fs.first_ba_held == 0); 1374 done2: 1375 return(fs.m); 1376 } 1377 1378 /* 1379 * Fault in the specified (object,offset), dirty the returned page as 1380 * needed. If the requested fault_type cannot be done NULL and an 1381 * error is returned. 1382 * 1383 * A held (but not busied) page is returned. 1384 * 1385 * The passed in object must be held as specified by the shared 1386 * argument. 1387 */ 1388 vm_page_t 1389 vm_fault_object_page(vm_object_t object, vm_ooffset_t offset, 1390 vm_prot_t fault_type, int fault_flags, 1391 int *sharedp, int *errorp) 1392 { 1393 int result; 1394 vm_pindex_t first_pindex; 1395 struct faultstate fs; 1396 struct vm_map_entry entry; 1397 1398 /* 1399 * Since we aren't actually faulting the page into a 1400 * pmap we can just fake the entry.ba. 1401 */ 1402 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 1403 bzero(&entry, sizeof(entry)); 1404 entry.maptype = VM_MAPTYPE_NORMAL; 1405 entry.protection = entry.max_protection = fault_type; 1406 entry.ba.backing_ba = NULL; 1407 entry.ba.object = object; 1408 entry.ba.offset = 0; 1409 1410 fs.hardfault = 0; 1411 fs.fault_flags = fault_flags; 1412 fs.map = NULL; 1413 fs.shared = vm_shared_fault; 1414 fs.first_shared = *sharedp; 1415 fs.msoftonly = 0; 1416 fs.vp = NULL; 1417 fs.first_ba_held = -1; /* object held across call, prevent drop */ 1418 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0); 1419 1420 /* 1421 * VM_FAULT_UNSWAP - swap_pager_unswapped() needs an exclusive object 1422 * VM_FAULT_DIRTY - may require swap_pager_unswapped() later, but 1423 * we can try shared first. 1424 */ 1425 if (fs.first_shared && (fault_flags & VM_FAULT_UNSWAP)) { 1426 fs.first_shared = 0; 1427 vm_object_upgrade(object); 1428 } 1429 1430 /* 1431 * Retry loop as needed (typically for shared->exclusive transitions) 1432 */ 1433 RetryFault: 1434 *sharedp = fs.first_shared; 1435 first_pindex = OFF_TO_IDX(offset); 1436 fs.first_ba = &entry.ba; 1437 fs.ba = fs.first_ba; 1438 fs.entry = &entry; 1439 fs.first_prot = fault_type; 1440 fs.wflags = 0; 1441 1442 /* 1443 * Make a reference to this object to prevent its disposal while we 1444 * are messing with it. Once we have the reference, the map is free 1445 * to be diddled. Since objects reference their shadows (and copies), 1446 * they will stay around as well. 1447 * 1448 * The reference should also prevent an unexpected collapse of the 1449 * parent that might move pages from the current object into the 1450 * parent unexpectedly, resulting in corruption. 1451 * 1452 * Bump the paging-in-progress count to prevent size changes (e.g. 1453 * truncation operations) during I/O. This must be done after 1454 * obtaining the vnode lock in order to avoid possible deadlocks. 1455 */ 1456 if (fs.vp == NULL) 1457 fs.vp = vnode_pager_lock(fs.first_ba); 1458 1459 fs.lookup_still_valid = 1; 1460 fs.first_m = NULL; 1461 1462 #if 0 1463 /* XXX future - ability to operate on VM object using vpagetable */ 1464 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) { 1465 result = vm_fault_vpagetable(&fs, &first_pindex, 1466 fs.entry->aux.master_pde, 1467 fault_type, 0); 1468 if (result == KERN_TRY_AGAIN) { 1469 if (fs.first_shared == 0 && *sharedp) 1470 vm_object_upgrade(object); 1471 goto RetryFault; 1472 } 1473 if (result != KERN_SUCCESS) { 1474 *errorp = result; 1475 return (NULL); 1476 } 1477 } 1478 #endif 1479 1480 /* 1481 * Now we have the actual (object, pindex), fault in the page. If 1482 * vm_fault_object() fails it will unlock and deallocate the FS 1483 * data. If it succeeds everything remains locked and fs->ba->object 1484 * will have an additinal PIP count if fs->ba != fs->first_ba. 1485 * 1486 * On KERN_TRY_AGAIN vm_fault_object() leaves fs.first_ba intact. 1487 * We may have to upgrade its lock to handle the requested fault. 1488 */ 1489 result = vm_fault_object(&fs, first_pindex, fault_type, 0); 1490 1491 if (result == KERN_TRY_AGAIN) { 1492 if (fs.first_shared == 0 && *sharedp) 1493 vm_object_upgrade(object); 1494 goto RetryFault; 1495 } 1496 if (result != KERN_SUCCESS) { 1497 *errorp = result; 1498 return(NULL); 1499 } 1500 1501 if ((fault_type & VM_PROT_WRITE) && (fs.prot & VM_PROT_WRITE) == 0) { 1502 *errorp = KERN_PROTECTION_FAILURE; 1503 unlock_things(&fs); 1504 return(NULL); 1505 } 1506 1507 /* 1508 * On success vm_fault_object() does not unlock or deallocate, so we 1509 * do it here. Note that the returned fs.m will be busied. 1510 */ 1511 unlock_things(&fs); 1512 1513 /* 1514 * Return a held page. We are not doing any pmap manipulation so do 1515 * not set PG_MAPPED. However, adjust the page flags according to 1516 * the fault type because the caller may not use a managed pmapping 1517 * (so we don't want to lose the fact that the page will be dirtied 1518 * if a write fault was specified). 1519 */ 1520 vm_page_hold(fs.m); 1521 vm_page_activate(fs.m); 1522 if ((fault_type & VM_PROT_WRITE) || (fault_flags & VM_FAULT_DIRTY)) 1523 vm_page_dirty(fs.m); 1524 if (fault_flags & VM_FAULT_UNSWAP) 1525 swap_pager_unswapped(fs.m); 1526 1527 /* 1528 * Indicate that the page was accessed. 1529 */ 1530 vm_page_flag_set(fs.m, PG_REFERENCED); 1531 1532 if (curthread->td_lwp) { 1533 if (fs.hardfault) { 1534 curthread->td_lwp->lwp_ru.ru_majflt++; 1535 } else { 1536 curthread->td_lwp->lwp_ru.ru_minflt++; 1537 } 1538 } 1539 1540 /* 1541 * Unlock everything, and return the held page. 1542 */ 1543 vm_page_wakeup(fs.m); 1544 /*vm_object_deallocate(fs.first_ba->object);*/ 1545 1546 *errorp = 0; 1547 return(fs.m); 1548 } 1549 1550 /* 1551 * Translate the virtual page number (first_pindex) that is relative 1552 * to the address space into a logical page number that is relative to the 1553 * backing object. Use the virtual page table pointed to by (vpte). 1554 * 1555 * Possibly downgrade the protection based on the vpte bits. 1556 * 1557 * This implements an N-level page table. Any level can terminate the 1558 * scan by setting VPTE_PS. A linear mapping is accomplished by setting 1559 * VPTE_PS in the master page directory entry set via mcontrol(MADV_SETMAP). 1560 */ 1561 static 1562 int 1563 vm_fault_vpagetable(struct faultstate *fs, vm_pindex_t *pindex, 1564 vpte_t vpte, int fault_type, int allow_nofault) 1565 { 1566 struct lwbuf *lwb; 1567 struct lwbuf lwb_cache; 1568 int vshift = VPTE_FRAME_END - PAGE_SHIFT; /* index bits remaining */ 1569 int result; 1570 vpte_t *ptep; 1571 1572 ASSERT_LWKT_TOKEN_HELD(vm_object_token(fs->first_ba->object)); 1573 for (;;) { 1574 /* 1575 * We cannot proceed if the vpte is not valid, not readable 1576 * for a read fault, not writable for a write fault, or 1577 * not executable for an instruction execution fault. 1578 */ 1579 if ((vpte & VPTE_V) == 0) { 1580 unlock_things(fs); 1581 return (KERN_FAILURE); 1582 } 1583 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_RW) == 0) { 1584 unlock_things(fs); 1585 return (KERN_FAILURE); 1586 } 1587 if ((fault_type & VM_PROT_EXECUTE) && (vpte & VPTE_NX)) { 1588 unlock_things(fs); 1589 return (KERN_FAILURE); 1590 } 1591 if ((vpte & VPTE_PS) || vshift == 0) 1592 break; 1593 1594 /* 1595 * Get the page table page. Nominally we only read the page 1596 * table, but since we are actively setting VPTE_M and VPTE_A, 1597 * tell vm_fault_object() that we are writing it. 1598 * 1599 * There is currently no real need to optimize this. 1600 */ 1601 result = vm_fault_object(fs, (vpte & VPTE_FRAME) >> PAGE_SHIFT, 1602 VM_PROT_READ|VM_PROT_WRITE, 1603 allow_nofault); 1604 if (result != KERN_SUCCESS) 1605 return (result); 1606 1607 /* 1608 * Process the returned fs.m and look up the page table 1609 * entry in the page table page. 1610 */ 1611 vshift -= VPTE_PAGE_BITS; 1612 lwb = lwbuf_alloc(fs->m, &lwb_cache); 1613 ptep = ((vpte_t *)lwbuf_kva(lwb) + 1614 ((*pindex >> vshift) & VPTE_PAGE_MASK)); 1615 vm_page_activate(fs->m); 1616 1617 /* 1618 * Page table write-back - entire operation including 1619 * validation of the pte must be atomic to avoid races 1620 * against the vkernel changing the pte. 1621 * 1622 * If the vpte is valid for the* requested operation, do 1623 * a write-back to the page table. 1624 * 1625 * XXX VPTE_M is not set properly for page directory pages. 1626 * It doesn't get set in the page directory if the page table 1627 * is modified during a read access. 1628 */ 1629 for (;;) { 1630 vpte_t nvpte; 1631 1632 /* 1633 * Reload for the cmpset, but make sure the pte is 1634 * still valid. 1635 */ 1636 vpte = *ptep; 1637 cpu_ccfence(); 1638 nvpte = vpte; 1639 1640 if ((vpte & VPTE_V) == 0) 1641 break; 1642 1643 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_RW)) 1644 nvpte |= VPTE_M | VPTE_A; 1645 if (fault_type & (VM_PROT_READ | VM_PROT_EXECUTE)) 1646 nvpte |= VPTE_A; 1647 if (vpte == nvpte) 1648 break; 1649 if (atomic_cmpset_long(ptep, vpte, nvpte)) { 1650 vm_page_dirty(fs->m); 1651 break; 1652 } 1653 } 1654 lwbuf_free(lwb); 1655 vm_page_flag_set(fs->m, PG_REFERENCED); 1656 vm_page_wakeup(fs->m); 1657 fs->m = NULL; 1658 cleanup_fault(fs); 1659 } 1660 1661 /* 1662 * When the vkernel sets VPTE_RW it expects the real kernel to 1663 * reflect VPTE_M back when the page is modified via the mapping. 1664 * In order to accomplish this the real kernel must map the page 1665 * read-only for read faults and use write faults to reflect VPTE_M 1666 * back. 1667 * 1668 * Once VPTE_M has been set, the real kernel's pte allows writing. 1669 * If the vkernel clears VPTE_M the vkernel must be sure to 1670 * MADV_INVAL the real kernel's mappings to force the real kernel 1671 * to re-fault on the next write so oit can set VPTE_M again. 1672 */ 1673 if ((fault_type & VM_PROT_WRITE) == 0 && 1674 (vpte & (VPTE_RW | VPTE_M)) != (VPTE_RW | VPTE_M)) { 1675 fs->first_prot &= ~VM_PROT_WRITE; 1676 } 1677 1678 /* 1679 * Disable EXECUTE perms if NX bit is set. 1680 */ 1681 if (vpte & VPTE_NX) 1682 fs->first_prot &= ~VM_PROT_EXECUTE; 1683 1684 /* 1685 * Combine remaining address bits with the vpte. 1686 */ 1687 *pindex = ((vpte & VPTE_FRAME) >> PAGE_SHIFT) + 1688 (*pindex & ((1L << vshift) - 1)); 1689 return (KERN_SUCCESS); 1690 } 1691 1692 1693 /* 1694 * This is the core of the vm_fault code. 1695 * 1696 * Do all operations required to fault-in (fs.first_ba->object, pindex). 1697 * Run through the backing store as necessary and do required COW or virtual 1698 * copy operations. The caller has already fully resolved the vm_map_entry 1699 * and, if appropriate, has created a copy-on-write layer. All we need to 1700 * do is iterate the object chain. 1701 * 1702 * On failure (fs) is unlocked and deallocated and the caller may return or 1703 * retry depending on the failure code. On success (fs) is NOT unlocked or 1704 * deallocated, fs.m will contained a resolved, busied page, and fs.ba's 1705 * object will have an additional PIP count if it is not equal to 1706 * fs.first_ba. 1707 * 1708 * If locks based on fs->first_shared or fs->shared are insufficient, 1709 * clear the appropriate field(s) and return RETRY. COWs require that 1710 * first_shared be 0, while page allocations (or frees) require that 1711 * shared be 0. Renames require that both be 0. 1712 * 1713 * NOTE! fs->[first_]shared might be set with VM_FAULT_DIRTY also set. 1714 * we will have to retry with it exclusive if the vm_page is 1715 * PG_SWAPPED. 1716 * 1717 * fs->first_ba->object must be held on call. 1718 */ 1719 static 1720 int 1721 vm_fault_object(struct faultstate *fs, vm_pindex_t first_pindex, 1722 vm_prot_t fault_type, int allow_nofault) 1723 { 1724 vm_map_backing_t next_ba; 1725 vm_pindex_t pindex; 1726 int error; 1727 1728 ASSERT_LWKT_TOKEN_HELD(vm_object_token(fs->first_ba->object)); 1729 fs->prot = fs->first_prot; 1730 pindex = first_pindex; 1731 KKASSERT(fs->ba == fs->first_ba); 1732 1733 vm_object_pip_add(fs->first_ba->object, 1); 1734 1735 /* 1736 * If a read fault occurs we try to upgrade the page protection 1737 * and make it also writable if possible. There are three cases 1738 * where we cannot make the page mapping writable: 1739 * 1740 * (1) The mapping is read-only or the VM object is read-only, 1741 * fs->prot above will simply not have VM_PROT_WRITE set. 1742 * 1743 * (2) If the mapping is a virtual page table fs->first_prot will 1744 * have already been properly adjusted by vm_fault_vpagetable(). 1745 * to detect writes so we can set VPTE_M in the virtual page 1746 * table. Used by vkernels. 1747 * 1748 * (3) If the VM page is read-only or copy-on-write, upgrading would 1749 * just result in an unnecessary COW fault. 1750 * 1751 * (4) If the pmap specifically requests A/M bit emulation, downgrade 1752 * here. 1753 */ 1754 #if 0 1755 /* see vpagetable code */ 1756 if (fs->entry->maptype == VM_MAPTYPE_VPAGETABLE) { 1757 if ((fault_type & VM_PROT_WRITE) == 0) 1758 fs->prot &= ~VM_PROT_WRITE; 1759 } 1760 #endif 1761 1762 if (curthread->td_lwp && curthread->td_lwp->lwp_vmspace && 1763 pmap_emulate_ad_bits(&curthread->td_lwp->lwp_vmspace->vm_pmap)) { 1764 if ((fault_type & VM_PROT_WRITE) == 0) 1765 fs->prot &= ~VM_PROT_WRITE; 1766 } 1767 1768 /* vm_object_hold(fs->ba->object); implied b/c ba == first_ba */ 1769 1770 for (;;) { 1771 /* 1772 * If the object is dead, we stop here 1773 */ 1774 if (fs->ba->object->flags & OBJ_DEAD) { 1775 vm_object_pip_wakeup(fs->first_ba->object); 1776 unlock_things(fs); 1777 return (KERN_PROTECTION_FAILURE); 1778 } 1779 1780 /* 1781 * See if the page is resident. Wait/Retry if the page is 1782 * busy (lots of stuff may have changed so we can't continue 1783 * in that case). 1784 * 1785 * We can theoretically allow the soft-busy case on a read 1786 * fault if the page is marked valid, but since such 1787 * pages are typically already pmap'd, putting that 1788 * special case in might be more effort then it is 1789 * worth. We cannot under any circumstances mess 1790 * around with a vm_page_t->busy page except, perhaps, 1791 * to pmap it. 1792 */ 1793 fs->m = vm_page_lookup_busy_try(fs->ba->object, pindex, 1794 TRUE, &error); 1795 if (error) { 1796 vm_object_pip_wakeup(fs->first_ba->object); 1797 unlock_things(fs); 1798 vm_page_sleep_busy(fs->m, TRUE, "vmpfw"); 1799 mycpu->gd_cnt.v_intrans++; 1800 fs->m = NULL; 1801 return (KERN_TRY_AGAIN); 1802 } 1803 if (fs->m) { 1804 /* 1805 * The page is busied for us. 1806 * 1807 * If reactivating a page from PQ_CACHE we may have 1808 * to rate-limit. 1809 */ 1810 int queue = fs->m->queue; 1811 vm_page_unqueue_nowakeup(fs->m); 1812 1813 if ((queue - fs->m->pc) == PQ_CACHE && 1814 vm_page_count_severe()) { 1815 vm_page_activate(fs->m); 1816 vm_page_wakeup(fs->m); 1817 fs->m = NULL; 1818 vm_object_pip_wakeup(fs->first_ba->object); 1819 unlock_things(fs); 1820 if (allow_nofault == 0 || 1821 (curthread->td_flags & TDF_NOFAULT) == 0) { 1822 thread_t td; 1823 1824 vm_wait_pfault(); 1825 td = curthread; 1826 if (td->td_proc && (td->td_proc->p_flags & P_LOWMEMKILL)) 1827 return (KERN_PROTECTION_FAILURE); 1828 } 1829 return (KERN_TRY_AGAIN); 1830 } 1831 1832 /* 1833 * If it still isn't completely valid (readable), 1834 * or if a read-ahead-mark is set on the VM page, 1835 * jump to readrest, else we found the page and 1836 * can return. 1837 * 1838 * We can release the spl once we have marked the 1839 * page busy. 1840 */ 1841 if (fs->m->object != &kernel_object) { 1842 if ((fs->m->valid & VM_PAGE_BITS_ALL) != 1843 VM_PAGE_BITS_ALL) { 1844 goto readrest; 1845 } 1846 if (fs->m->flags & PG_RAM) { 1847 if (debug_cluster) 1848 kprintf("R"); 1849 vm_page_flag_clear(fs->m, PG_RAM); 1850 goto readrest; 1851 } 1852 } 1853 fs->first_ba->flags &= ~VM_MAP_BACK_EXCL_HEUR; 1854 break; /* break to PAGE HAS BEEN FOUND */ 1855 } 1856 1857 /* 1858 * Page is not resident, If this is the search termination 1859 * or the pager might contain the page, allocate a new page. 1860 */ 1861 if (TRYPAGER(fs) || fs->ba == fs->first_ba) { 1862 /* 1863 * If this is a SWAP object we can use the shared 1864 * lock to check existence of a swap block. If 1865 * there isn't one we can skip to the next object. 1866 * 1867 * However, if this is the first object we allocate 1868 * a page now just in case we need to copy to it 1869 * later. 1870 */ 1871 if (fs->ba != fs->first_ba && 1872 fs->ba->object->type == OBJT_SWAP) { 1873 if (swap_pager_haspage_locked(fs->ba->object, 1874 pindex) == 0) { 1875 goto next; 1876 } 1877 } 1878 1879 /* 1880 * Allocating, must be exclusive. 1881 */ 1882 fs->first_ba->flags |= VM_MAP_BACK_EXCL_HEUR; 1883 if (fs->ba == fs->first_ba && fs->first_shared) { 1884 fs->first_shared = 0; 1885 vm_object_pip_wakeup(fs->first_ba->object); 1886 unlock_things(fs); 1887 return (KERN_TRY_AGAIN); 1888 } 1889 if (fs->ba != fs->first_ba && fs->shared) { 1890 fs->first_shared = 0; 1891 fs->shared = 0; 1892 vm_object_pip_wakeup(fs->first_ba->object); 1893 unlock_things(fs); 1894 return (KERN_TRY_AGAIN); 1895 } 1896 1897 /* 1898 * If the page is beyond the object size we fail 1899 */ 1900 if (pindex >= fs->ba->object->size) { 1901 vm_object_pip_wakeup(fs->first_ba->object); 1902 unlock_things(fs); 1903 return (KERN_PROTECTION_FAILURE); 1904 } 1905 1906 /* 1907 * Allocate a new page for this object/offset pair. 1908 * 1909 * It is possible for the allocation to race, so 1910 * handle the case. 1911 */ 1912 fs->m = NULL; 1913 if (!vm_page_count_severe()) { 1914 fs->m = vm_page_alloc(fs->ba->object, pindex, 1915 ((fs->vp || fs->ba->backing_ba) ? 1916 VM_ALLOC_NULL_OK | VM_ALLOC_NORMAL : 1917 VM_ALLOC_NULL_OK | VM_ALLOC_NORMAL | 1918 VM_ALLOC_USE_GD | VM_ALLOC_ZERO)); 1919 } 1920 if (fs->m == NULL) { 1921 vm_object_pip_wakeup(fs->first_ba->object); 1922 unlock_things(fs); 1923 if (allow_nofault == 0 || 1924 (curthread->td_flags & TDF_NOFAULT) == 0) { 1925 thread_t td; 1926 1927 vm_wait_pfault(); 1928 td = curthread; 1929 if (td->td_proc && (td->td_proc->p_flags & P_LOWMEMKILL)) 1930 return (KERN_PROTECTION_FAILURE); 1931 } 1932 return (KERN_TRY_AGAIN); 1933 } 1934 1935 /* 1936 * Fall through to readrest. We have a new page which 1937 * will have to be paged (since m->valid will be 0). 1938 */ 1939 } 1940 1941 readrest: 1942 /* 1943 * We have found an invalid or partially valid page, a 1944 * page with a read-ahead mark which might be partially or 1945 * fully valid (and maybe dirty too), or we have allocated 1946 * a new page. 1947 * 1948 * Attempt to fault-in the page if there is a chance that the 1949 * pager has it, and potentially fault in additional pages 1950 * at the same time. 1951 * 1952 * If TRYPAGER is true then fs.m will be non-NULL and busied 1953 * for us. 1954 */ 1955 if (TRYPAGER(fs)) { 1956 u_char behavior = vm_map_entry_behavior(fs->entry); 1957 vm_object_t object; 1958 vm_page_t first_m; 1959 int seqaccess; 1960 int rv; 1961 1962 if (behavior == MAP_ENTRY_BEHAV_RANDOM) 1963 seqaccess = 0; 1964 else 1965 seqaccess = -1; 1966 1967 /* 1968 * Doing I/O may synchronously insert additional 1969 * pages so we can't be shared at this point either. 1970 * 1971 * NOTE: We can't free fs->m here in the allocated 1972 * case (fs->ba != fs->first_ba) as this 1973 * would require an exclusively locked 1974 * VM object. 1975 */ 1976 if (fs->ba == fs->first_ba && fs->first_shared) { 1977 vm_page_deactivate(fs->m); 1978 vm_page_wakeup(fs->m); 1979 fs->m = NULL; 1980 fs->first_shared = 0; 1981 vm_object_pip_wakeup(fs->first_ba->object); 1982 unlock_things(fs); 1983 return (KERN_TRY_AGAIN); 1984 } 1985 if (fs->ba != fs->first_ba && fs->shared) { 1986 vm_page_deactivate(fs->m); 1987 vm_page_wakeup(fs->m); 1988 fs->m = NULL; 1989 fs->first_shared = 0; 1990 fs->shared = 0; 1991 vm_object_pip_wakeup(fs->first_ba->object); 1992 unlock_things(fs); 1993 return (KERN_TRY_AGAIN); 1994 } 1995 1996 object = fs->ba->object; 1997 first_m = NULL; 1998 1999 /* object is held, no more access to entry or ba's */ 2000 2001 /* 2002 * Acquire the page data. We still hold object 2003 * and the page has been BUSY's. 2004 * 2005 * We own the page, but we must re-issue the lookup 2006 * because the pager may have replaced it (for example, 2007 * in order to enter a fictitious page into the 2008 * object). In this situation the pager will have 2009 * cleaned up the old page and left the new one 2010 * busy for us. 2011 * 2012 * If we got here through a PG_RAM read-ahead 2013 * mark the page may be partially dirty and thus 2014 * not freeable. Don't bother checking to see 2015 * if the pager has the page because we can't free 2016 * it anyway. We have to depend on the get_page 2017 * operation filling in any gaps whether there is 2018 * backing store or not. 2019 * 2020 * We must dispose of the page (fs->m) and also 2021 * possibly first_m (the fronting layer). If 2022 * this is a write fault leave the page intact 2023 * because we will probably have to copy fs->m 2024 * to fs->first_m on the retry. If this is a 2025 * read fault we probably won't need the page. 2026 */ 2027 rv = vm_pager_get_page(object, &fs->m, seqaccess); 2028 2029 if (rv == VM_PAGER_OK) { 2030 ++fs->hardfault; 2031 fs->m = vm_page_lookup(object, pindex); 2032 if (fs->m) { 2033 vm_page_activate(fs->m); 2034 vm_page_wakeup(fs->m); 2035 fs->m = NULL; 2036 } 2037 2038 if (fs->m) { 2039 /* have page */ 2040 break; 2041 } 2042 vm_object_pip_wakeup(fs->first_ba->object); 2043 unlock_things(fs); 2044 return (KERN_TRY_AGAIN); 2045 } 2046 2047 /* 2048 * If the pager doesn't have the page, continue on 2049 * to the next object. Retain the vm_page if this 2050 * is the first object, we may need to copy into 2051 * it later. 2052 */ 2053 if (rv == VM_PAGER_FAIL) { 2054 if (fs->ba != fs->first_ba) { 2055 vm_page_free(fs->m); 2056 fs->m = NULL; 2057 } 2058 goto next; 2059 } 2060 2061 /* 2062 * Remove the bogus page (which does not exist at this 2063 * object/offset). 2064 * 2065 * Also wake up any other process that may want to bring 2066 * in this page. 2067 * 2068 * If this is the top-level object, we must leave the 2069 * busy page to prevent another process from rushing 2070 * past us, and inserting the page in that object at 2071 * the same time that we are. 2072 */ 2073 if (rv == VM_PAGER_ERROR) { 2074 if (curproc) { 2075 kprintf("vm_fault: pager read error, " 2076 "pid %d (%s)\n", 2077 curproc->p_pid, 2078 curproc->p_comm); 2079 } else { 2080 kprintf("vm_fault: pager read error, " 2081 "thread %p (%s)\n", 2082 curthread, 2083 curthread->td_comm); 2084 } 2085 } 2086 2087 /* 2088 * I/O error or data outside pager's range. 2089 */ 2090 if (fs->m) { 2091 vnode_pager_freepage(fs->m); 2092 fs->m = NULL; 2093 } 2094 if (first_m) { 2095 vm_page_free(first_m); 2096 first_m = NULL; /* safety */ 2097 } 2098 vm_object_pip_wakeup(object); 2099 unlock_things(fs); 2100 2101 switch(rv) { 2102 case VM_PAGER_ERROR: 2103 return (KERN_FAILURE); 2104 case VM_PAGER_BAD: 2105 return (KERN_PROTECTION_FAILURE); 2106 default: 2107 return (KERN_PROTECTION_FAILURE); 2108 } 2109 2110 #if 0 2111 /* 2112 * Data outside the range of the pager or an I/O error 2113 * 2114 * The page may have been wired during the pagein, 2115 * e.g. by the buffer cache, and cannot simply be 2116 * freed. Call vnode_pager_freepage() to deal with it. 2117 * 2118 * The object is not held shared so we can safely 2119 * free the page. 2120 */ 2121 if (fs->ba != fs->first_ba) { 2122 2123 /* 2124 * XXX - we cannot just fall out at this 2125 * point, m has been freed and is invalid! 2126 */ 2127 } 2128 2129 /* 2130 * XXX - the check for kernel_map is a kludge to work 2131 * around having the machine panic on a kernel space 2132 * fault w/ I/O error. 2133 */ 2134 if (((fs->map != &kernel_map) && 2135 (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) { 2136 if (fs->m) { 2137 /* from just above */ 2138 KKASSERT(fs->first_shared == 0); 2139 vnode_pager_freepage(fs->m); 2140 fs->m = NULL; 2141 } 2142 /* NOT REACHED */ 2143 } 2144 #endif 2145 } 2146 2147 next: 2148 /* 2149 * We get here if the object has a default pager (or unwiring) 2150 * or the pager doesn't have the page. 2151 * 2152 * fs->first_m will be used for the COW unless we find a 2153 * deeper page to be mapped read-only, in which case the 2154 * unlock*(fs) will free first_m. 2155 */ 2156 if (fs->ba == fs->first_ba) 2157 fs->first_m = fs->m; 2158 2159 /* 2160 * Move on to the next object. The chain lock should prevent 2161 * the backing_object from getting ripped out from under us. 2162 * 2163 * The object lock for the next object is governed by 2164 * fs->shared. 2165 */ 2166 next_ba = fs->ba->backing_ba; 2167 if (next_ba == NULL) { 2168 /* 2169 * If there's no object left, fill the page in the top 2170 * object with zeros. 2171 */ 2172 if (fs->ba != fs->first_ba) { 2173 vm_object_pip_wakeup(fs->ba->object); 2174 vm_object_drop(fs->ba->object); 2175 fs->ba = fs->first_ba; 2176 pindex = first_pindex; 2177 fs->m = fs->first_m; 2178 } 2179 fs->first_m = NULL; 2180 2181 /* 2182 * Zero the page and mark it valid. 2183 */ 2184 vm_page_zero_fill(fs->m); 2185 mycpu->gd_cnt.v_zfod++; 2186 fs->m->valid = VM_PAGE_BITS_ALL; 2187 break; /* break to PAGE HAS BEEN FOUND */ 2188 } 2189 2190 if (fs->shared) 2191 vm_object_hold_shared(next_ba->object); 2192 else 2193 vm_object_hold(next_ba->object); 2194 KKASSERT(next_ba == fs->ba->backing_ba); 2195 pindex -= OFF_TO_IDX(fs->ba->offset); 2196 pindex += OFF_TO_IDX(next_ba->offset); 2197 2198 if (fs->ba != fs->first_ba) { 2199 vm_object_pip_wakeup(fs->ba->object); 2200 vm_object_lock_swap(); /* flip ba/next_ba */ 2201 vm_object_drop(fs->ba->object); 2202 } 2203 fs->ba = next_ba; 2204 vm_object_pip_add(next_ba->object, 1); 2205 } 2206 2207 /* 2208 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 2209 * is held.] 2210 * 2211 * object still held. 2212 * vm_map may not be locked (determined by fs->lookup_still_valid) 2213 * 2214 * local shared variable may be different from fs->shared. 2215 * 2216 * If the page is being written, but isn't already owned by the 2217 * top-level object, we have to copy it into a new page owned by the 2218 * top-level object. 2219 */ 2220 KASSERT((fs->m->busy_count & PBUSY_LOCKED) != 0, 2221 ("vm_fault: not busy after main loop")); 2222 2223 if (fs->ba != fs->first_ba) { 2224 /* 2225 * We only really need to copy if we want to write it. 2226 */ 2227 if (fault_type & VM_PROT_WRITE) { 2228 #if 0 2229 /* CODE REFACTOR IN PROGRESS, REMOVE OPTIMIZATION */ 2230 /* 2231 * This allows pages to be virtually copied from a 2232 * backing_object into the first_object, where the 2233 * backing object has no other refs to it, and cannot 2234 * gain any more refs. Instead of a bcopy, we just 2235 * move the page from the backing object to the 2236 * first object. Note that we must mark the page 2237 * dirty in the first object so that it will go out 2238 * to swap when needed. 2239 */ 2240 if (virtual_copy_ok(fs)) { 2241 /* 2242 * (first_m) and (m) are both busied. We have 2243 * move (m) into (first_m)'s object/pindex 2244 * in an atomic fashion, then free (first_m). 2245 * 2246 * first_object is held so second remove 2247 * followed by the rename should wind 2248 * up being atomic. vm_page_free() might 2249 * block so we don't do it until after the 2250 * rename. 2251 */ 2252 vm_page_protect(fs->first_m, VM_PROT_NONE); 2253 vm_page_remove(fs->first_m); 2254 vm_page_rename(fs->m, 2255 fs->first_ba->object, 2256 first_pindex); 2257 vm_page_free(fs->first_m); 2258 fs->first_m = fs->m; 2259 fs->m = NULL; 2260 mycpu->gd_cnt.v_cow_optim++; 2261 } else 2262 #endif 2263 { 2264 /* 2265 * Oh, well, lets copy it. 2266 * 2267 * We used to unmap the original page here 2268 * because vm_fault_page() didn't and this 2269 * would cause havoc for the umtx*() code 2270 * and the procfs code. 2271 * 2272 * This is no longer necessary. The 2273 * vm_fault_page() routine will now unmap the 2274 * page after a COW, and the umtx code will 2275 * recover on its own. 2276 */ 2277 /* 2278 * NOTE: Since fs->m is a backing page, it 2279 * is read-only, so there isn't any 2280 * copy race vs writers. 2281 */ 2282 KKASSERT(fs->first_shared == 0); 2283 vm_page_copy(fs->m, fs->first_m); 2284 /* pmap_remove_specific( 2285 &curthread->td_lwp->lwp_vmspace->vm_pmap, 2286 fs->m); */ 2287 } 2288 2289 /* 2290 * We no longer need the old page or object. 2291 */ 2292 if (fs->m) 2293 release_page(fs); 2294 2295 /* 2296 * fs->ba != fs->first_ba due to above conditional 2297 */ 2298 vm_object_pip_wakeup(fs->ba->object); 2299 vm_object_drop(fs->ba->object); 2300 fs->ba = fs->first_ba; 2301 2302 /* 2303 * Only use the new page below... 2304 */ 2305 mycpu->gd_cnt.v_cow_faults++; 2306 fs->m = fs->first_m; 2307 pindex = first_pindex; 2308 } else { 2309 /* 2310 * If it wasn't a write fault avoid having to copy 2311 * the page by mapping it read-only from backing 2312 * store. The process is not allowed to modify 2313 * backing pages. 2314 */ 2315 fs->prot &= ~VM_PROT_WRITE; 2316 } 2317 } 2318 2319 /* 2320 * Relock the map if necessary, then check the generation count. 2321 * relock_map() will update fs->timestamp to account for the 2322 * relocking if necessary. 2323 * 2324 * If the count has changed after relocking then all sorts of 2325 * crap may have happened and we have to retry. 2326 * 2327 * NOTE: The relock_map() can fail due to a deadlock against 2328 * the vm_page we are holding BUSY. 2329 */ 2330 KKASSERT(fs->lookup_still_valid != 0); 2331 #if 0 2332 if (fs->lookup_still_valid == 0 && fs->map) { 2333 if (relock_map(fs) || 2334 fs->map->timestamp != fs->map_generation) { 2335 release_page(fs); 2336 vm_object_pip_wakeup(fs->first_ba->object); 2337 unlock_things(fs); 2338 return (KERN_TRY_AGAIN); 2339 } 2340 } 2341 #endif 2342 2343 /* 2344 * If the fault is a write, we know that this page is being 2345 * written NOW so dirty it explicitly to save on pmap_is_modified() 2346 * calls later. 2347 * 2348 * If this is a NOSYNC mmap we do not want to set PG_NOSYNC 2349 * if the page is already dirty to prevent data written with 2350 * the expectation of being synced from not being synced. 2351 * Likewise if this entry does not request NOSYNC then make 2352 * sure the page isn't marked NOSYNC. Applications sharing 2353 * data should use the same flags to avoid ping ponging. 2354 * 2355 * Also tell the backing pager, if any, that it should remove 2356 * any swap backing since the page is now dirty. 2357 */ 2358 vm_page_activate(fs->m); 2359 if (fs->prot & VM_PROT_WRITE) { 2360 vm_object_set_writeable_dirty(fs->m->object); 2361 vm_set_nosync(fs->m, fs->entry); 2362 if (fs->fault_flags & VM_FAULT_DIRTY) { 2363 vm_page_dirty(fs->m); 2364 if (fs->m->flags & PG_SWAPPED) { 2365 /* 2366 * If the page is swapped out we have to call 2367 * swap_pager_unswapped() which requires an 2368 * exclusive object lock. If we are shared, 2369 * we must clear the shared flag and retry. 2370 */ 2371 if ((fs->ba == fs->first_ba && 2372 fs->first_shared) || 2373 (fs->ba != fs->first_ba && fs->shared)) { 2374 vm_page_wakeup(fs->m); 2375 fs->m = NULL; 2376 if (fs->ba == fs->first_ba) 2377 fs->first_shared = 0; 2378 else 2379 fs->shared = 0; 2380 vm_object_pip_wakeup( 2381 fs->first_ba->object); 2382 unlock_things(fs); 2383 return (KERN_TRY_AGAIN); 2384 } 2385 swap_pager_unswapped(fs->m); 2386 } 2387 } 2388 } 2389 2390 /* 2391 * We found our page at backing layer ba. Leave the layer state 2392 * intact. 2393 */ 2394 2395 vm_object_pip_wakeup(fs->first_ba->object); 2396 #if 0 2397 if (fs->ba != fs->first_ba) 2398 vm_object_drop(fs->ba->object); 2399 #endif 2400 2401 /* 2402 * Page had better still be busy. We are still locked up and 2403 * fs->ba->object will have another PIP reference for the case 2404 * where fs->ba != fs->first_ba. 2405 */ 2406 KASSERT(fs->m->busy_count & PBUSY_LOCKED, 2407 ("vm_fault: page %p not busy!", fs->m)); 2408 2409 /* 2410 * Sanity check: page must be completely valid or it is not fit to 2411 * map into user space. vm_pager_get_pages() ensures this. 2412 */ 2413 if (fs->m->valid != VM_PAGE_BITS_ALL) { 2414 vm_page_zero_invalid(fs->m, TRUE); 2415 kprintf("Warning: page %p partially invalid on fault\n", fs->m); 2416 } 2417 2418 return (KERN_SUCCESS); 2419 } 2420 2421 /* 2422 * Wire down a range of virtual addresses in a map. The entry in question 2423 * should be marked in-transition and the map must be locked. We must 2424 * release the map temporarily while faulting-in the page to avoid a 2425 * deadlock. Note that the entry may be clipped while we are blocked but 2426 * will never be freed. 2427 * 2428 * map must be locked on entry. 2429 */ 2430 int 2431 vm_fault_wire(vm_map_t map, vm_map_entry_t entry, 2432 boolean_t user_wire, int kmflags) 2433 { 2434 boolean_t fictitious; 2435 vm_offset_t start; 2436 vm_offset_t end; 2437 vm_offset_t va; 2438 pmap_t pmap; 2439 int rv; 2440 int wire_prot; 2441 int fault_flags; 2442 vm_page_t m; 2443 2444 if (user_wire) { 2445 wire_prot = VM_PROT_READ; 2446 fault_flags = VM_FAULT_USER_WIRE; 2447 } else { 2448 wire_prot = VM_PROT_READ | VM_PROT_WRITE; 2449 fault_flags = VM_FAULT_CHANGE_WIRING; 2450 } 2451 if (kmflags & KM_NOTLBSYNC) 2452 wire_prot |= VM_PROT_NOSYNC; 2453 2454 pmap = vm_map_pmap(map); 2455 start = entry->ba.start; 2456 end = entry->ba.end; 2457 2458 switch(entry->maptype) { 2459 case VM_MAPTYPE_NORMAL: 2460 case VM_MAPTYPE_VPAGETABLE: 2461 fictitious = entry->ba.object && 2462 ((entry->ba.object->type == OBJT_DEVICE) || 2463 (entry->ba.object->type == OBJT_MGTDEVICE)); 2464 break; 2465 case VM_MAPTYPE_UKSMAP: 2466 fictitious = TRUE; 2467 break; 2468 default: 2469 fictitious = FALSE; 2470 break; 2471 } 2472 2473 if (entry->eflags & MAP_ENTRY_KSTACK) 2474 start += PAGE_SIZE; 2475 map->timestamp++; 2476 vm_map_unlock(map); 2477 2478 /* 2479 * We simulate a fault to get the page and enter it in the physical 2480 * map. 2481 */ 2482 for (va = start; va < end; va += PAGE_SIZE) { 2483 rv = vm_fault(map, va, wire_prot, fault_flags); 2484 if (rv) { 2485 while (va > start) { 2486 va -= PAGE_SIZE; 2487 m = pmap_unwire(pmap, va); 2488 if (m && !fictitious) { 2489 vm_page_busy_wait(m, FALSE, "vmwrpg"); 2490 vm_page_unwire(m, 1); 2491 vm_page_wakeup(m); 2492 } 2493 } 2494 goto done; 2495 } 2496 } 2497 rv = KERN_SUCCESS; 2498 done: 2499 vm_map_lock(map); 2500 2501 return (rv); 2502 } 2503 2504 /* 2505 * Unwire a range of virtual addresses in a map. The map should be 2506 * locked. 2507 */ 2508 void 2509 vm_fault_unwire(vm_map_t map, vm_map_entry_t entry) 2510 { 2511 boolean_t fictitious; 2512 vm_offset_t start; 2513 vm_offset_t end; 2514 vm_offset_t va; 2515 pmap_t pmap; 2516 vm_page_t m; 2517 2518 pmap = vm_map_pmap(map); 2519 start = entry->ba.start; 2520 end = entry->ba.end; 2521 fictitious = entry->ba.object && 2522 ((entry->ba.object->type == OBJT_DEVICE) || 2523 (entry->ba.object->type == OBJT_MGTDEVICE)); 2524 if (entry->eflags & MAP_ENTRY_KSTACK) 2525 start += PAGE_SIZE; 2526 2527 /* 2528 * Since the pages are wired down, we must be able to get their 2529 * mappings from the physical map system. 2530 */ 2531 for (va = start; va < end; va += PAGE_SIZE) { 2532 m = pmap_unwire(pmap, va); 2533 if (m && !fictitious) { 2534 vm_page_busy_wait(m, FALSE, "vmwrpg"); 2535 vm_page_unwire(m, 1); 2536 vm_page_wakeup(m); 2537 } 2538 } 2539 } 2540 2541 /* 2542 * Simulate write faults to bring all data into the head object, return 2543 * KERN_SUCCESS on success (which should be always unless the system runs 2544 * out of memory). 2545 * 2546 * The caller will handle destroying the backing_ba's. 2547 */ 2548 int 2549 vm_fault_collapse(vm_map_t map, vm_map_entry_t entry) 2550 { 2551 struct faultstate fs; 2552 vm_ooffset_t scan; 2553 vm_pindex_t pindex; 2554 vm_object_t object; 2555 int rv; 2556 int all_shadowed; 2557 2558 bzero(&fs, sizeof(fs)); 2559 object = entry->ba.object; 2560 2561 fs.first_prot = entry->max_protection | /* optional VM_PROT_EXECUTE */ 2562 VM_PROT_READ | VM_PROT_WRITE | VM_PROT_OVERRIDE_WRITE; 2563 fs.fault_flags = VM_FAULT_NORMAL; 2564 fs.map = map; 2565 fs.entry = entry; 2566 fs.lookup_still_valid = -1; /* leave map atomically locked */ 2567 fs.first_ba = &entry->ba; 2568 fs.first_ba_held = -1; /* leave object held */ 2569 2570 /* fs.hardfault */ 2571 2572 vm_object_hold(object); 2573 rv = KERN_SUCCESS; 2574 2575 scan = entry->ba.start; 2576 all_shadowed = 1; 2577 2578 while (scan < entry->ba.end) { 2579 pindex = OFF_TO_IDX(entry->ba.offset + (scan - entry->ba.start)); 2580 2581 if (vm_page_lookup(object, pindex)) { 2582 scan += PAGE_SIZE; 2583 continue; 2584 } 2585 2586 all_shadowed = 0; 2587 fs.ba = fs.first_ba; 2588 fs.prot = fs.first_prot; 2589 2590 rv = vm_fault_object(&fs, pindex, fs.first_prot, 1); 2591 if (rv == KERN_TRY_AGAIN) 2592 continue; 2593 if (rv != KERN_SUCCESS) 2594 break; 2595 vm_page_flag_set(fs.m, PG_REFERENCED); 2596 vm_page_activate(fs.m); 2597 vm_page_wakeup(fs.m); 2598 scan += PAGE_SIZE; 2599 } 2600 KKASSERT(entry->ba.object == object); 2601 vm_object_drop(object); 2602 2603 /* 2604 * If the fronting object did not have every page we have to clear 2605 * the pmap range due to the pages being changed so we can fault-in 2606 * the proper pages. 2607 */ 2608 if (all_shadowed == 0) 2609 pmap_remove(map->pmap, entry->ba.start, entry->ba.end); 2610 2611 return rv; 2612 } 2613 2614 /* 2615 * Copy all of the pages from one map entry to another. If the source 2616 * is wired down we just use vm_page_lookup(). If not we use 2617 * vm_fault_object(). 2618 * 2619 * The source and destination maps must be locked for write. 2620 * The source and destination maps token must be held 2621 * 2622 * No other requirements. 2623 * 2624 * XXX do segment optimization 2625 */ 2626 void 2627 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 2628 vm_map_entry_t dst_entry, vm_map_entry_t src_entry) 2629 { 2630 vm_object_t dst_object; 2631 vm_object_t src_object; 2632 vm_ooffset_t dst_offset; 2633 vm_ooffset_t src_offset; 2634 vm_prot_t prot; 2635 vm_offset_t vaddr; 2636 vm_page_t dst_m; 2637 vm_page_t src_m; 2638 2639 src_object = src_entry->ba.object; 2640 src_offset = src_entry->ba.offset; 2641 2642 /* 2643 * Create the top-level object for the destination entry. (Doesn't 2644 * actually shadow anything - we copy the pages directly.) 2645 */ 2646 vm_map_entry_allocate_object(dst_entry); 2647 dst_object = dst_entry->ba.object; 2648 2649 prot = dst_entry->max_protection; 2650 2651 /* 2652 * Loop through all of the pages in the entry's range, copying each 2653 * one from the source object (it should be there) to the destination 2654 * object. 2655 */ 2656 vm_object_hold(src_object); 2657 vm_object_hold(dst_object); 2658 2659 for (vaddr = dst_entry->ba.start, dst_offset = 0; 2660 vaddr < dst_entry->ba.end; 2661 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) { 2662 2663 /* 2664 * Allocate a page in the destination object 2665 */ 2666 do { 2667 dst_m = vm_page_alloc(dst_object, 2668 OFF_TO_IDX(dst_offset), 2669 VM_ALLOC_NORMAL); 2670 if (dst_m == NULL) { 2671 vm_wait(0); 2672 } 2673 } while (dst_m == NULL); 2674 2675 /* 2676 * Find the page in the source object, and copy it in. 2677 * (Because the source is wired down, the page will be in 2678 * memory.) 2679 */ 2680 src_m = vm_page_lookup(src_object, 2681 OFF_TO_IDX(dst_offset + src_offset)); 2682 if (src_m == NULL) 2683 panic("vm_fault_copy_wired: page missing"); 2684 2685 vm_page_copy(src_m, dst_m); 2686 2687 /* 2688 * Enter it in the pmap... 2689 */ 2690 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE, dst_entry); 2691 2692 /* 2693 * Mark it no longer busy, and put it on the active list. 2694 */ 2695 vm_page_activate(dst_m); 2696 vm_page_wakeup(dst_m); 2697 } 2698 vm_object_drop(dst_object); 2699 vm_object_drop(src_object); 2700 } 2701 2702 #if 0 2703 2704 /* 2705 * This routine checks around the requested page for other pages that 2706 * might be able to be faulted in. This routine brackets the viable 2707 * pages for the pages to be paged in. 2708 * 2709 * Inputs: 2710 * m, rbehind, rahead 2711 * 2712 * Outputs: 2713 * marray (array of vm_page_t), reqpage (index of requested page) 2714 * 2715 * Return value: 2716 * number of pages in marray 2717 */ 2718 static int 2719 vm_fault_additional_pages(vm_page_t m, int rbehind, int rahead, 2720 vm_page_t *marray, int *reqpage) 2721 { 2722 int i,j; 2723 vm_object_t object; 2724 vm_pindex_t pindex, startpindex, endpindex, tpindex; 2725 vm_page_t rtm; 2726 int cbehind, cahead; 2727 2728 object = m->object; 2729 pindex = m->pindex; 2730 2731 /* 2732 * we don't fault-ahead for device pager 2733 */ 2734 if ((object->type == OBJT_DEVICE) || 2735 (object->type == OBJT_MGTDEVICE)) { 2736 *reqpage = 0; 2737 marray[0] = m; 2738 return 1; 2739 } 2740 2741 /* 2742 * if the requested page is not available, then give up now 2743 */ 2744 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 2745 *reqpage = 0; /* not used by caller, fix compiler warn */ 2746 return 0; 2747 } 2748 2749 if ((cbehind == 0) && (cahead == 0)) { 2750 *reqpage = 0; 2751 marray[0] = m; 2752 return 1; 2753 } 2754 2755 if (rahead > cahead) { 2756 rahead = cahead; 2757 } 2758 2759 if (rbehind > cbehind) { 2760 rbehind = cbehind; 2761 } 2762 2763 /* 2764 * Do not do any readahead if we have insufficient free memory. 2765 * 2766 * XXX code was broken disabled before and has instability 2767 * with this conditonal fixed, so shortcut for now. 2768 */ 2769 if (burst_fault == 0 || vm_page_count_severe()) { 2770 marray[0] = m; 2771 *reqpage = 0; 2772 return 1; 2773 } 2774 2775 /* 2776 * scan backward for the read behind pages -- in memory 2777 * 2778 * Assume that if the page is not found an interrupt will not 2779 * create it. Theoretically interrupts can only remove (busy) 2780 * pages, not create new associations. 2781 */ 2782 if (pindex > 0) { 2783 if (rbehind > pindex) { 2784 rbehind = pindex; 2785 startpindex = 0; 2786 } else { 2787 startpindex = pindex - rbehind; 2788 } 2789 2790 vm_object_hold(object); 2791 for (tpindex = pindex; tpindex > startpindex; --tpindex) { 2792 if (vm_page_lookup(object, tpindex - 1)) 2793 break; 2794 } 2795 2796 i = 0; 2797 while (tpindex < pindex) { 2798 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM | 2799 VM_ALLOC_NULL_OK); 2800 if (rtm == NULL) { 2801 for (j = 0; j < i; j++) { 2802 vm_page_free(marray[j]); 2803 } 2804 vm_object_drop(object); 2805 marray[0] = m; 2806 *reqpage = 0; 2807 return 1; 2808 } 2809 marray[i] = rtm; 2810 ++i; 2811 ++tpindex; 2812 } 2813 vm_object_drop(object); 2814 } else { 2815 i = 0; 2816 } 2817 2818 /* 2819 * Assign requested page 2820 */ 2821 marray[i] = m; 2822 *reqpage = i; 2823 ++i; 2824 2825 /* 2826 * Scan forwards for read-ahead pages 2827 */ 2828 tpindex = pindex + 1; 2829 endpindex = tpindex + rahead; 2830 if (endpindex > object->size) 2831 endpindex = object->size; 2832 2833 vm_object_hold(object); 2834 while (tpindex < endpindex) { 2835 if (vm_page_lookup(object, tpindex)) 2836 break; 2837 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM | 2838 VM_ALLOC_NULL_OK); 2839 if (rtm == NULL) 2840 break; 2841 marray[i] = rtm; 2842 ++i; 2843 ++tpindex; 2844 } 2845 vm_object_drop(object); 2846 2847 return (i); 2848 } 2849 2850 #endif 2851 2852 /* 2853 * vm_prefault() provides a quick way of clustering pagefaults into a 2854 * processes address space. It is a "cousin" of pmap_object_init_pt, 2855 * except it runs at page fault time instead of mmap time. 2856 * 2857 * vm.fast_fault Enables pre-faulting zero-fill pages 2858 * 2859 * vm.prefault_pages Number of pages (1/2 negative, 1/2 positive) to 2860 * prefault. Scan stops in either direction when 2861 * a page is found to already exist. 2862 * 2863 * This code used to be per-platform pmap_prefault(). It is now 2864 * machine-independent and enhanced to also pre-fault zero-fill pages 2865 * (see vm.fast_fault) as well as make them writable, which greatly 2866 * reduces the number of page faults programs incur. 2867 * 2868 * Application performance when pre-faulting zero-fill pages is heavily 2869 * dependent on the application. Very tiny applications like /bin/echo 2870 * lose a little performance while applications of any appreciable size 2871 * gain performance. Prefaulting multiple pages also reduces SMP 2872 * congestion and can improve SMP performance significantly. 2873 * 2874 * NOTE! prot may allow writing but this only applies to the top level 2875 * object. If we wind up mapping a page extracted from a backing 2876 * object we have to make sure it is read-only. 2877 * 2878 * NOTE! The caller has already handled any COW operations on the 2879 * vm_map_entry via the normal fault code. Do NOT call this 2880 * shortcut unless the normal fault code has run on this entry. 2881 * 2882 * The related map must be locked. 2883 * No other requirements. 2884 */ 2885 __read_mostly static int vm_prefault_pages = 8; 2886 SYSCTL_INT(_vm, OID_AUTO, prefault_pages, CTLFLAG_RW, &vm_prefault_pages, 0, 2887 "Maximum number of pages to pre-fault"); 2888 __read_mostly static int vm_fast_fault = 1; 2889 SYSCTL_INT(_vm, OID_AUTO, fast_fault, CTLFLAG_RW, &vm_fast_fault, 0, 2890 "Burst fault zero-fill regions"); 2891 2892 /* 2893 * Set PG_NOSYNC if the map entry indicates so, but only if the page 2894 * is not already dirty by other means. This will prevent passive 2895 * filesystem syncing as well as 'sync' from writing out the page. 2896 */ 2897 static void 2898 vm_set_nosync(vm_page_t m, vm_map_entry_t entry) 2899 { 2900 if (entry->eflags & MAP_ENTRY_NOSYNC) { 2901 if (m->dirty == 0) 2902 vm_page_flag_set(m, PG_NOSYNC); 2903 } else { 2904 vm_page_flag_clear(m, PG_NOSYNC); 2905 } 2906 } 2907 2908 static void 2909 vm_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry, int prot, 2910 int fault_flags) 2911 { 2912 vm_map_backing_t ba; /* first ba */ 2913 struct lwp *lp; 2914 vm_page_t m; 2915 vm_offset_t addr; 2916 vm_pindex_t index; 2917 vm_pindex_t pindex; 2918 vm_object_t object; 2919 int pprot; 2920 int i; 2921 int noneg; 2922 int nopos; 2923 int maxpages; 2924 2925 /* 2926 * Get stable max count value, disabled if set to 0 2927 */ 2928 maxpages = vm_prefault_pages; 2929 cpu_ccfence(); 2930 if (maxpages <= 0) 2931 return; 2932 2933 /* 2934 * We do not currently prefault mappings that use virtual page 2935 * tables. We do not prefault foreign pmaps. 2936 */ 2937 if (entry->maptype != VM_MAPTYPE_NORMAL) 2938 return; 2939 lp = curthread->td_lwp; 2940 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace))) 2941 return; 2942 2943 /* 2944 * Limit pre-fault count to 1024 pages. 2945 */ 2946 if (maxpages > 1024) 2947 maxpages = 1024; 2948 2949 ba = &entry->ba; 2950 object = entry->ba.object; 2951 KKASSERT(object != NULL); 2952 2953 /* 2954 * NOTE: VM_FAULT_DIRTY allowed later so must hold object exclusively 2955 * now (or do something more complex XXX). 2956 */ 2957 vm_object_hold(object); 2958 2959 noneg = 0; 2960 nopos = 0; 2961 for (i = 0; i < maxpages; ++i) { 2962 vm_object_t lobject; 2963 vm_object_t nobject; 2964 vm_map_backing_t last_ba; /* last ba */ 2965 vm_map_backing_t next_ba; /* last ba */ 2966 int allocated = 0; 2967 int error; 2968 2969 /* 2970 * This can eat a lot of time on a heavily contended 2971 * machine so yield on the tick if needed. 2972 */ 2973 if ((i & 7) == 7) 2974 lwkt_yield(); 2975 2976 /* 2977 * Calculate the page to pre-fault, stopping the scan in 2978 * each direction separately if the limit is reached. 2979 */ 2980 if (i & 1) { 2981 if (noneg) 2982 continue; 2983 addr = addra - ((i + 1) >> 1) * PAGE_SIZE; 2984 } else { 2985 if (nopos) 2986 continue; 2987 addr = addra + ((i + 2) >> 1) * PAGE_SIZE; 2988 } 2989 if (addr < entry->ba.start) { 2990 noneg = 1; 2991 if (noneg && nopos) 2992 break; 2993 continue; 2994 } 2995 if (addr >= entry->ba.end) { 2996 nopos = 1; 2997 if (noneg && nopos) 2998 break; 2999 continue; 3000 } 3001 3002 /* 3003 * Skip pages already mapped, and stop scanning in that 3004 * direction. When the scan terminates in both directions 3005 * we are done. 3006 */ 3007 if (pmap_prefault_ok(pmap, addr) == 0) { 3008 if (i & 1) 3009 noneg = 1; 3010 else 3011 nopos = 1; 3012 if (noneg && nopos) 3013 break; 3014 continue; 3015 } 3016 3017 /* 3018 * Follow the backing layers to obtain the page to be mapped 3019 * into the pmap. 3020 * 3021 * If we reach the terminal object without finding a page 3022 * and we determine it would be advantageous, then allocate 3023 * a zero-fill page for the base object. The base object 3024 * is guaranteed to be OBJT_DEFAULT for this case. 3025 * 3026 * In order to not have to check the pager via *haspage*() 3027 * we stop if any non-default object is encountered. e.g. 3028 * a vnode or swap object would stop the loop. 3029 */ 3030 index = ((addr - entry->ba.start) + entry->ba.offset) >> 3031 PAGE_SHIFT; 3032 last_ba = ba; 3033 lobject = object; 3034 pindex = index; 3035 pprot = prot; 3036 3037 /*vm_object_hold(lobject); implied */ 3038 3039 while ((m = vm_page_lookup_busy_try(lobject, pindex, 3040 TRUE, &error)) == NULL) { 3041 if (lobject->type != OBJT_DEFAULT) 3042 break; 3043 if ((next_ba = last_ba->backing_ba) == NULL) { 3044 if (vm_fast_fault == 0) 3045 break; 3046 if ((prot & VM_PROT_WRITE) == 0 || 3047 vm_page_count_min(0)) { 3048 break; 3049 } 3050 3051 /* 3052 * NOTE: Allocated from base object 3053 */ 3054 m = vm_page_alloc(object, index, 3055 VM_ALLOC_NORMAL | 3056 VM_ALLOC_ZERO | 3057 VM_ALLOC_USE_GD | 3058 VM_ALLOC_NULL_OK); 3059 if (m == NULL) 3060 break; 3061 allocated = 1; 3062 pprot = prot; 3063 /* lobject = object .. not needed */ 3064 break; 3065 } 3066 if (next_ba->offset & PAGE_MASK) 3067 break; 3068 nobject = next_ba->object; 3069 vm_object_hold(nobject); 3070 pindex -= last_ba->offset >> PAGE_SHIFT; 3071 pindex += next_ba->offset >> PAGE_SHIFT; 3072 if (last_ba != ba) { 3073 vm_object_lock_swap(); 3074 vm_object_drop(lobject); 3075 } 3076 lobject = nobject; 3077 last_ba = next_ba; 3078 pprot &= ~VM_PROT_WRITE; 3079 } 3080 3081 /* 3082 * NOTE: A non-NULL (m) will be associated with lobject if 3083 * it was found there, otherwise it is probably a 3084 * zero-fill page associated with the base object. 3085 * 3086 * Give-up if no page is available. 3087 */ 3088 if (m == NULL) { 3089 if (last_ba != ba) 3090 vm_object_drop(lobject); 3091 break; 3092 } 3093 3094 /* 3095 * The object must be marked dirty if we are mapping a 3096 * writable page. m->object is either lobject or object, 3097 * both of which are still held. Do this before we 3098 * potentially drop the object. 3099 */ 3100 if (pprot & VM_PROT_WRITE) 3101 vm_object_set_writeable_dirty(m->object); 3102 3103 /* 3104 * Do not conditionalize on PG_RAM. If pages are present in 3105 * the VM system we assume optimal caching. If caching is 3106 * not optimal the I/O gravy train will be restarted when we 3107 * hit an unavailable page. We do not want to try to restart 3108 * the gravy train now because we really don't know how much 3109 * of the object has been cached. The cost for restarting 3110 * the gravy train should be low (since accesses will likely 3111 * be I/O bound anyway). 3112 */ 3113 if (last_ba != ba) 3114 vm_object_drop(lobject); 3115 3116 /* 3117 * Enter the page into the pmap if appropriate. If we had 3118 * allocated the page we have to place it on a queue. If not 3119 * we just have to make sure it isn't on the cache queue 3120 * (pages on the cache queue are not allowed to be mapped). 3121 */ 3122 if (allocated) { 3123 /* 3124 * Page must be zerod. 3125 */ 3126 vm_page_zero_fill(m); 3127 mycpu->gd_cnt.v_zfod++; 3128 m->valid = VM_PAGE_BITS_ALL; 3129 3130 /* 3131 * Handle dirty page case 3132 */ 3133 if (pprot & VM_PROT_WRITE) 3134 vm_set_nosync(m, entry); 3135 pmap_enter(pmap, addr, m, pprot, 0, entry); 3136 mycpu->gd_cnt.v_vm_faults++; 3137 if (curthread->td_lwp) 3138 ++curthread->td_lwp->lwp_ru.ru_minflt; 3139 vm_page_deactivate(m); 3140 if (pprot & VM_PROT_WRITE) { 3141 /*vm_object_set_writeable_dirty(m->object);*/ 3142 vm_set_nosync(m, entry); 3143 if (fault_flags & VM_FAULT_DIRTY) { 3144 vm_page_dirty(m); 3145 /*XXX*/ 3146 swap_pager_unswapped(m); 3147 } 3148 } 3149 vm_page_wakeup(m); 3150 } else if (error) { 3151 /* couldn't busy page, no wakeup */ 3152 } else if ( 3153 ((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) && 3154 (m->flags & PG_FICTITIOUS) == 0) { 3155 /* 3156 * A fully valid page not undergoing soft I/O can 3157 * be immediately entered into the pmap. 3158 */ 3159 if ((m->queue - m->pc) == PQ_CACHE) 3160 vm_page_deactivate(m); 3161 if (pprot & VM_PROT_WRITE) { 3162 /*vm_object_set_writeable_dirty(m->object);*/ 3163 vm_set_nosync(m, entry); 3164 if (fault_flags & VM_FAULT_DIRTY) { 3165 vm_page_dirty(m); 3166 /*XXX*/ 3167 swap_pager_unswapped(m); 3168 } 3169 } 3170 if (pprot & VM_PROT_WRITE) 3171 vm_set_nosync(m, entry); 3172 pmap_enter(pmap, addr, m, pprot, 0, entry); 3173 mycpu->gd_cnt.v_vm_faults++; 3174 if (curthread->td_lwp) 3175 ++curthread->td_lwp->lwp_ru.ru_minflt; 3176 vm_page_wakeup(m); 3177 } else { 3178 vm_page_wakeup(m); 3179 } 3180 } 3181 vm_object_drop(object); 3182 } 3183 3184 /* 3185 * Object can be held shared 3186 */ 3187 static void 3188 vm_prefault_quick(pmap_t pmap, vm_offset_t addra, 3189 vm_map_entry_t entry, int prot, int fault_flags) 3190 { 3191 struct lwp *lp; 3192 vm_page_t m; 3193 vm_offset_t addr; 3194 vm_pindex_t pindex; 3195 vm_object_t object; 3196 int i; 3197 int noneg; 3198 int nopos; 3199 int maxpages; 3200 3201 /* 3202 * Get stable max count value, disabled if set to 0 3203 */ 3204 maxpages = vm_prefault_pages; 3205 cpu_ccfence(); 3206 if (maxpages <= 0) 3207 return; 3208 3209 /* 3210 * We do not currently prefault mappings that use virtual page 3211 * tables. We do not prefault foreign pmaps. 3212 */ 3213 if (entry->maptype != VM_MAPTYPE_NORMAL) 3214 return; 3215 lp = curthread->td_lwp; 3216 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace))) 3217 return; 3218 object = entry->ba.object; 3219 if (entry->ba.backing_ba != NULL) 3220 return; 3221 ASSERT_LWKT_TOKEN_HELD(vm_object_token(object)); 3222 3223 /* 3224 * Limit pre-fault count to 1024 pages. 3225 */ 3226 if (maxpages > 1024) 3227 maxpages = 1024; 3228 3229 noneg = 0; 3230 nopos = 0; 3231 for (i = 0; i < maxpages; ++i) { 3232 int error; 3233 3234 /* 3235 * Calculate the page to pre-fault, stopping the scan in 3236 * each direction separately if the limit is reached. 3237 */ 3238 if (i & 1) { 3239 if (noneg) 3240 continue; 3241 addr = addra - ((i + 1) >> 1) * PAGE_SIZE; 3242 } else { 3243 if (nopos) 3244 continue; 3245 addr = addra + ((i + 2) >> 1) * PAGE_SIZE; 3246 } 3247 if (addr < entry->ba.start) { 3248 noneg = 1; 3249 if (noneg && nopos) 3250 break; 3251 continue; 3252 } 3253 if (addr >= entry->ba.end) { 3254 nopos = 1; 3255 if (noneg && nopos) 3256 break; 3257 continue; 3258 } 3259 3260 /* 3261 * Follow the VM object chain to obtain the page to be mapped 3262 * into the pmap. This version of the prefault code only 3263 * works with terminal objects. 3264 * 3265 * The page must already exist. If we encounter a problem 3266 * we stop here. 3267 * 3268 * WARNING! We cannot call swap_pager_unswapped() or insert 3269 * a new vm_page with a shared token. 3270 */ 3271 pindex = ((addr - entry->ba.start) + entry->ba.offset) >> 3272 PAGE_SHIFT; 3273 3274 /* 3275 * Skip pages already mapped, and stop scanning in that 3276 * direction. When the scan terminates in both directions 3277 * we are done. 3278 */ 3279 if (pmap_prefault_ok(pmap, addr) == 0) { 3280 if (i & 1) 3281 noneg = 1; 3282 else 3283 nopos = 1; 3284 if (noneg && nopos) 3285 break; 3286 continue; 3287 } 3288 3289 /* 3290 * Shortcut the read-only mapping case using the far more 3291 * efficient vm_page_lookup_sbusy_try() function. This 3292 * allows us to acquire the page soft-busied only which 3293 * is especially nice for concurrent execs of the same 3294 * program. 3295 * 3296 * The lookup function also validates page suitability 3297 * (all valid bits set, and not fictitious). 3298 * 3299 * If the page is in PQ_CACHE we have to fall-through 3300 * and hard-busy it so we can move it out of PQ_CACHE. 3301 */ 3302 if ((prot & VM_PROT_WRITE) == 0) { 3303 m = vm_page_lookup_sbusy_try(object, pindex, 3304 0, PAGE_SIZE); 3305 if (m == NULL) 3306 break; 3307 if ((m->queue - m->pc) != PQ_CACHE) { 3308 pmap_enter(pmap, addr, m, prot, 0, entry); 3309 mycpu->gd_cnt.v_vm_faults++; 3310 if (curthread->td_lwp) 3311 ++curthread->td_lwp->lwp_ru.ru_minflt; 3312 vm_page_sbusy_drop(m); 3313 continue; 3314 } 3315 vm_page_sbusy_drop(m); 3316 } 3317 3318 /* 3319 * Fallback to normal vm_page lookup code. This code 3320 * hard-busies the page. Not only that, but the page 3321 * can remain in that state for a significant period 3322 * time due to pmap_enter()'s overhead. 3323 */ 3324 m = vm_page_lookup_busy_try(object, pindex, TRUE, &error); 3325 if (m == NULL || error) 3326 break; 3327 3328 /* 3329 * Stop if the page cannot be trivially entered into the 3330 * pmap. 3331 */ 3332 if (((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) || 3333 (m->flags & PG_FICTITIOUS) || 3334 ((m->flags & PG_SWAPPED) && 3335 (prot & VM_PROT_WRITE) && 3336 (fault_flags & VM_FAULT_DIRTY))) { 3337 vm_page_wakeup(m); 3338 break; 3339 } 3340 3341 /* 3342 * Enter the page into the pmap. The object might be held 3343 * shared so we can't do any (serious) modifying operation 3344 * on it. 3345 */ 3346 if ((m->queue - m->pc) == PQ_CACHE) 3347 vm_page_deactivate(m); 3348 if (prot & VM_PROT_WRITE) { 3349 vm_object_set_writeable_dirty(m->object); 3350 vm_set_nosync(m, entry); 3351 if (fault_flags & VM_FAULT_DIRTY) { 3352 vm_page_dirty(m); 3353 /* can't happeen due to conditional above */ 3354 /* swap_pager_unswapped(m); */ 3355 } 3356 } 3357 pmap_enter(pmap, addr, m, prot, 0, entry); 3358 mycpu->gd_cnt.v_vm_faults++; 3359 if (curthread->td_lwp) 3360 ++curthread->td_lwp->lwp_ru.ru_minflt; 3361 vm_page_wakeup(m); 3362 } 3363 } 3364