1 /* 2 * (MPSAFE) 3 * 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * Copyright (c) 1994 John S. Dyson 7 * All rights reserved. 8 * Copyright (c) 1994 David Greenman 9 * All rights reserved. 10 * 11 * 12 * This code is derived from software contributed to Berkeley by 13 * The Mach Operating System project at Carnegie-Mellon University. 14 * 15 * Redistribution and use in source and binary forms, with or without 16 * modification, are permitted provided that the following conditions 17 * are met: 18 * 1. Redistributions of source code must retain the above copyright 19 * notice, this list of conditions and the following disclaimer. 20 * 2. Redistributions in binary form must reproduce the above copyright 21 * notice, this list of conditions and the following disclaimer in the 22 * documentation and/or other materials provided with the distribution. 23 * 3. All advertising materials mentioning features or use of this software 24 * must display the following acknowledgement: 25 * This product includes software developed by the University of 26 * California, Berkeley and its contributors. 27 * 4. Neither the name of the University nor the names of its contributors 28 * may be used to endorse or promote products derived from this software 29 * without specific prior written permission. 30 * 31 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 32 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 33 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 34 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 35 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 36 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 37 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 39 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 40 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 41 * SUCH DAMAGE. 42 * 43 * from: @(#)vm_fault.c 8.4 (Berkeley) 1/12/94 44 * 45 * 46 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 47 * All rights reserved. 48 * 49 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 50 * 51 * Permission to use, copy, modify and distribute this software and 52 * its documentation is hereby granted, provided that both the copyright 53 * notice and this permission notice appear in all copies of the 54 * software, derivative works or modified versions, and any portions 55 * thereof, and that both notices appear in supporting documentation. 56 * 57 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 58 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 59 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 60 * 61 * Carnegie Mellon requests users of this software to return to 62 * 63 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 64 * School of Computer Science 65 * Carnegie Mellon University 66 * Pittsburgh PA 15213-3890 67 * 68 * any improvements or extensions that they make and grant Carnegie the 69 * rights to redistribute these changes. 70 * 71 * $FreeBSD: src/sys/vm/vm_fault.c,v 1.108.2.8 2002/02/26 05:49:27 silby Exp $ 72 * $DragonFly: src/sys/vm/vm_fault.c,v 1.47 2008/07/01 02:02:56 dillon Exp $ 73 */ 74 75 /* 76 * Page fault handling module. 77 */ 78 79 #include <sys/param.h> 80 #include <sys/systm.h> 81 #include <sys/kernel.h> 82 #include <sys/proc.h> 83 #include <sys/vnode.h> 84 #include <sys/resourcevar.h> 85 #include <sys/vmmeter.h> 86 #include <sys/vkernel.h> 87 #include <sys/lock.h> 88 #include <sys/sysctl.h> 89 90 #include <cpu/lwbuf.h> 91 92 #include <vm/vm.h> 93 #include <vm/vm_param.h> 94 #include <vm/pmap.h> 95 #include <vm/vm_map.h> 96 #include <vm/vm_object.h> 97 #include <vm/vm_page.h> 98 #include <vm/vm_pageout.h> 99 #include <vm/vm_kern.h> 100 #include <vm/vm_pager.h> 101 #include <vm/vnode_pager.h> 102 #include <vm/vm_extern.h> 103 104 #include <sys/thread2.h> 105 #include <vm/vm_page2.h> 106 107 struct faultstate { 108 vm_page_t m; 109 vm_object_t object; 110 vm_pindex_t pindex; 111 vm_prot_t prot; 112 vm_page_t first_m; 113 vm_object_t first_object; 114 vm_prot_t first_prot; 115 vm_map_t map; 116 vm_map_entry_t entry; 117 int lookup_still_valid; 118 int didlimit; 119 int hardfault; 120 int fault_flags; 121 int map_generation; 122 boolean_t wired; 123 struct vnode *vp; 124 }; 125 126 static int vm_fast_fault = 1; 127 SYSCTL_INT(_vm, OID_AUTO, fast_fault, CTLFLAG_RW, &vm_fast_fault, 0, 128 "Burst fault zero-fill regions"); 129 static int debug_cluster = 0; 130 SYSCTL_INT(_vm, OID_AUTO, debug_cluster, CTLFLAG_RW, &debug_cluster, 0, ""); 131 132 static int vm_fault_object(struct faultstate *, vm_pindex_t, vm_prot_t); 133 static int vm_fault_vpagetable(struct faultstate *, vm_pindex_t *, vpte_t, int); 134 #if 0 135 static int vm_fault_additional_pages (vm_page_t, int, int, vm_page_t *, int *); 136 #endif 137 static int vm_fault_ratelimit(struct vmspace *); 138 static void vm_set_nosync(vm_page_t m, vm_map_entry_t entry); 139 static void vm_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry, 140 int prot); 141 142 /* 143 * The caller must hold vm_token. 144 */ 145 static __inline void 146 release_page(struct faultstate *fs) 147 { 148 vm_page_deactivate(fs->m); 149 vm_page_wakeup(fs->m); 150 fs->m = NULL; 151 } 152 153 /* 154 * The caller must hold vm_token. 155 */ 156 static __inline void 157 unlock_map(struct faultstate *fs) 158 { 159 if (fs->lookup_still_valid && fs->map) { 160 vm_map_lookup_done(fs->map, fs->entry, 0); 161 fs->lookup_still_valid = FALSE; 162 } 163 } 164 165 /* 166 * Clean up after a successful call to vm_fault_object() so another call 167 * to vm_fault_object() can be made. 168 * 169 * The caller must hold vm_token. 170 */ 171 static void 172 _cleanup_successful_fault(struct faultstate *fs, int relock) 173 { 174 if (fs->object != fs->first_object) { 175 vm_page_free(fs->first_m); 176 vm_object_pip_wakeup(fs->object); 177 fs->first_m = NULL; 178 } 179 fs->object = fs->first_object; 180 if (relock && fs->lookup_still_valid == FALSE) { 181 if (fs->map) 182 vm_map_lock_read(fs->map); 183 fs->lookup_still_valid = TRUE; 184 } 185 } 186 187 /* 188 * The caller must hold vm_token. 189 */ 190 static void 191 _unlock_things(struct faultstate *fs, int dealloc) 192 { 193 vm_object_pip_wakeup(fs->first_object); 194 _cleanup_successful_fault(fs, 0); 195 if (dealloc) { 196 vm_object_deallocate(fs->first_object); 197 fs->first_object = NULL; 198 } 199 unlock_map(fs); 200 if (fs->vp != NULL) { 201 vput(fs->vp); 202 fs->vp = NULL; 203 } 204 } 205 206 #define unlock_things(fs) _unlock_things(fs, 0) 207 #define unlock_and_deallocate(fs) _unlock_things(fs, 1) 208 #define cleanup_successful_fault(fs) _cleanup_successful_fault(fs, 1) 209 210 /* 211 * TRYPAGER 212 * 213 * Determine if the pager for the current object *might* contain the page. 214 * 215 * We only need to try the pager if this is not a default object (default 216 * objects are zero-fill and have no real pager), and if we are not taking 217 * a wiring fault or if the FS entry is wired. 218 */ 219 #define TRYPAGER(fs) \ 220 (fs->object->type != OBJT_DEFAULT && \ 221 (((fs->fault_flags & VM_FAULT_WIRE_MASK) == 0) || fs->wired)) 222 223 /* 224 * vm_fault: 225 * 226 * Handle a page fault occuring at the given address, requiring the given 227 * permissions, in the map specified. If successful, the page is inserted 228 * into the associated physical map. 229 * 230 * NOTE: The given address should be truncated to the proper page address. 231 * 232 * KERN_SUCCESS is returned if the page fault is handled; otherwise, 233 * a standard error specifying why the fault is fatal is returned. 234 * 235 * The map in question must be referenced, and remains so. 236 * The caller may hold no locks. 237 * No other requirements. 238 */ 239 int 240 vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, int fault_flags) 241 { 242 int result; 243 vm_pindex_t first_pindex; 244 struct faultstate fs; 245 int growstack; 246 247 mycpu->gd_cnt.v_vm_faults++; 248 249 fs.didlimit = 0; 250 fs.hardfault = 0; 251 fs.fault_flags = fault_flags; 252 growstack = 1; 253 254 RetryFault: 255 /* 256 * Find the vm_map_entry representing the backing store and resolve 257 * the top level object and page index. This may have the side 258 * effect of executing a copy-on-write on the map entry and/or 259 * creating a shadow object, but will not COW any actual VM pages. 260 * 261 * On success fs.map is left read-locked and various other fields 262 * are initialized but not otherwise referenced or locked. 263 * 264 * NOTE! vm_map_lookup will try to upgrade the fault_type to 265 * VM_FAULT_WRITE if the map entry is a virtual page table and also 266 * writable, so we can set the 'A'accessed bit in the virtual page 267 * table entry. 268 */ 269 fs.map = map; 270 result = vm_map_lookup(&fs.map, vaddr, fault_type, 271 &fs.entry, &fs.first_object, 272 &first_pindex, &fs.first_prot, &fs.wired); 273 274 /* 275 * If the lookup failed or the map protections are incompatible, 276 * the fault generally fails. However, if the caller is trying 277 * to do a user wiring we have more work to do. 278 */ 279 if (result != KERN_SUCCESS) { 280 if (result != KERN_PROTECTION_FAILURE || 281 (fs.fault_flags & VM_FAULT_WIRE_MASK) != VM_FAULT_USER_WIRE) 282 { 283 if (result == KERN_INVALID_ADDRESS && growstack && 284 map != &kernel_map && curproc != NULL) { 285 result = vm_map_growstack(curproc, vaddr); 286 if (result != KERN_SUCCESS) 287 return (KERN_FAILURE); 288 growstack = 0; 289 goto RetryFault; 290 } 291 return (result); 292 } 293 294 /* 295 * If we are user-wiring a r/w segment, and it is COW, then 296 * we need to do the COW operation. Note that we don't 297 * currently COW RO sections now, because it is NOT desirable 298 * to COW .text. We simply keep .text from ever being COW'ed 299 * and take the heat that one cannot debug wired .text sections. 300 */ 301 result = vm_map_lookup(&fs.map, vaddr, 302 VM_PROT_READ|VM_PROT_WRITE| 303 VM_PROT_OVERRIDE_WRITE, 304 &fs.entry, &fs.first_object, 305 &first_pindex, &fs.first_prot, 306 &fs.wired); 307 if (result != KERN_SUCCESS) 308 return result; 309 310 /* 311 * If we don't COW now, on a user wire, the user will never 312 * be able to write to the mapping. If we don't make this 313 * restriction, the bookkeeping would be nearly impossible. 314 */ 315 if ((fs.entry->protection & VM_PROT_WRITE) == 0) 316 fs.entry->max_protection &= ~VM_PROT_WRITE; 317 } 318 319 /* 320 * fs.map is read-locked 321 * 322 * Misc checks. Save the map generation number to detect races. 323 */ 324 fs.map_generation = fs.map->timestamp; 325 326 if (fs.entry->eflags & (MAP_ENTRY_NOFAULT | MAP_ENTRY_KSTACK)) { 327 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 328 panic("vm_fault: fault on nofault entry, addr: %p", 329 (void *)vaddr); 330 } 331 if ((fs.entry->eflags & MAP_ENTRY_KSTACK) && 332 vaddr >= fs.entry->start && 333 vaddr < fs.entry->start + PAGE_SIZE) { 334 panic("vm_fault: fault on stack guard, addr: %p", 335 (void *)vaddr); 336 } 337 } 338 339 /* 340 * A system map entry may return a NULL object. No object means 341 * no pager means an unrecoverable kernel fault. 342 */ 343 if (fs.first_object == NULL) { 344 panic("vm_fault: unrecoverable fault at %p in entry %p", 345 (void *)vaddr, fs.entry); 346 } 347 348 /* 349 * Make a reference to this object to prevent its disposal while we 350 * are messing with it. Once we have the reference, the map is free 351 * to be diddled. Since objects reference their shadows (and copies), 352 * they will stay around as well. 353 * 354 * Bump the paging-in-progress count to prevent size changes (e.g. 355 * truncation operations) during I/O. This must be done after 356 * obtaining the vnode lock in order to avoid possible deadlocks. 357 * 358 * The vm_token is needed to manipulate the vm_object 359 */ 360 lwkt_gettoken(&vm_token); 361 vm_object_reference(fs.first_object); 362 fs.vp = vnode_pager_lock(fs.first_object); 363 vm_object_pip_add(fs.first_object, 1); 364 lwkt_reltoken(&vm_token); 365 366 fs.lookup_still_valid = TRUE; 367 fs.first_m = NULL; 368 fs.object = fs.first_object; /* so unlock_and_deallocate works */ 369 370 /* 371 * If the entry is wired we cannot change the page protection. 372 */ 373 if (fs.wired) 374 fault_type = fs.first_prot; 375 376 /* 377 * The page we want is at (first_object, first_pindex), but if the 378 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the 379 * page table to figure out the actual pindex. 380 * 381 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION 382 * ONLY 383 */ 384 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) { 385 result = vm_fault_vpagetable(&fs, &first_pindex, 386 fs.entry->aux.master_pde, 387 fault_type); 388 if (result == KERN_TRY_AGAIN) 389 goto RetryFault; 390 if (result != KERN_SUCCESS) 391 return (result); 392 } 393 394 /* 395 * Now we have the actual (object, pindex), fault in the page. If 396 * vm_fault_object() fails it will unlock and deallocate the FS 397 * data. If it succeeds everything remains locked and fs->object 398 * will have an additional PIP count if it is not equal to 399 * fs->first_object 400 * 401 * vm_fault_object will set fs->prot for the pmap operation. It is 402 * allowed to set VM_PROT_WRITE if fault_type == VM_PROT_READ if the 403 * page can be safely written. However, it will force a read-only 404 * mapping for a read fault if the memory is managed by a virtual 405 * page table. 406 */ 407 /* BEFORE */ 408 result = vm_fault_object(&fs, first_pindex, fault_type); 409 410 if (result == KERN_TRY_AGAIN) { 411 /*lwkt_reltoken(&vm_token);*/ 412 goto RetryFault; 413 } 414 if (result != KERN_SUCCESS) { 415 /*lwkt_reltoken(&vm_token);*/ 416 return (result); 417 } 418 419 /* 420 * On success vm_fault_object() does not unlock or deallocate, and fs.m 421 * will contain a busied page. 422 * 423 * Enter the page into the pmap and do pmap-related adjustments. 424 */ 425 vm_page_flag_set(fs.m, PG_REFERENCED); 426 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired); 427 428 /* 429 * Burst in a few more pages if possible. The fs.map should still 430 * be locked. 431 */ 432 if (fault_flags & VM_FAULT_BURST) { 433 if ((fs.fault_flags & VM_FAULT_WIRE_MASK) == 0 && 434 fs.wired == 0) { 435 vm_prefault(fs.map->pmap, vaddr, fs.entry, fs.prot); 436 } 437 } 438 lwkt_gettoken(&vm_token); 439 unlock_things(&fs); 440 441 /*KKASSERT(fs.m->queue == PQ_NONE); page-in op may deactivate page */ 442 KKASSERT(fs.m->flags & PG_BUSY); 443 444 /* 445 * If the page is not wired down, then put it where the pageout daemon 446 * can find it. 447 * 448 * We do not really need to get vm_token here but since all the 449 * vm_*() calls have to doing it here improves efficiency. 450 */ 451 /*lwkt_gettoken(&vm_token);*/ 452 453 if (fs.fault_flags & VM_FAULT_WIRE_MASK) { 454 lwkt_reltoken(&vm_token); /* before wire activate does not */ 455 if (fs.wired) 456 vm_page_wire(fs.m); 457 else 458 vm_page_unwire(fs.m, 1); 459 } else { 460 vm_page_activate(fs.m); 461 lwkt_reltoken(&vm_token); /* before wire activate does not */ 462 } 463 /*lwkt_reltoken(&vm_token); after wire/activate works */ 464 465 if (curthread->td_lwp) { 466 if (fs.hardfault) { 467 curthread->td_lwp->lwp_ru.ru_majflt++; 468 } else { 469 curthread->td_lwp->lwp_ru.ru_minflt++; 470 } 471 } 472 473 /* 474 * Unlock everything, and return 475 */ 476 vm_page_wakeup(fs.m); 477 vm_object_deallocate(fs.first_object); 478 /*fs.m = NULL; */ 479 /*fs.first_object = NULL; */ 480 /*lwkt_reltoken(&vm_token);*/ 481 482 return (KERN_SUCCESS); 483 } 484 485 /* 486 * Fault in the specified virtual address in the current process map, 487 * returning a held VM page or NULL. See vm_fault_page() for more 488 * information. 489 * 490 * No requirements. 491 */ 492 vm_page_t 493 vm_fault_page_quick(vm_offset_t va, vm_prot_t fault_type, int *errorp) 494 { 495 struct lwp *lp = curthread->td_lwp; 496 vm_page_t m; 497 498 m = vm_fault_page(&lp->lwp_vmspace->vm_map, va, 499 fault_type, VM_FAULT_NORMAL, errorp); 500 return(m); 501 } 502 503 /* 504 * Fault in the specified virtual address in the specified map, doing all 505 * necessary manipulation of the object store and all necessary I/O. Return 506 * a held VM page or NULL, and set *errorp. The related pmap is not 507 * updated. 508 * 509 * The returned page will be properly dirtied if VM_PROT_WRITE was specified, 510 * and marked PG_REFERENCED as well. 511 * 512 * If the page cannot be faulted writable and VM_PROT_WRITE was specified, an 513 * error will be returned. 514 * 515 * No requirements. 516 */ 517 vm_page_t 518 vm_fault_page(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type, 519 int fault_flags, int *errorp) 520 { 521 vm_pindex_t first_pindex; 522 struct faultstate fs; 523 int result; 524 vm_prot_t orig_fault_type = fault_type; 525 526 mycpu->gd_cnt.v_vm_faults++; 527 528 fs.didlimit = 0; 529 fs.hardfault = 0; 530 fs.fault_flags = fault_flags; 531 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0); 532 533 RetryFault: 534 /* 535 * Find the vm_map_entry representing the backing store and resolve 536 * the top level object and page index. This may have the side 537 * effect of executing a copy-on-write on the map entry and/or 538 * creating a shadow object, but will not COW any actual VM pages. 539 * 540 * On success fs.map is left read-locked and various other fields 541 * are initialized but not otherwise referenced or locked. 542 * 543 * NOTE! vm_map_lookup will upgrade the fault_type to VM_FAULT_WRITE 544 * if the map entry is a virtual page table and also writable, 545 * so we can set the 'A'accessed bit in the virtual page table entry. 546 */ 547 fs.map = map; 548 result = vm_map_lookup(&fs.map, vaddr, fault_type, 549 &fs.entry, &fs.first_object, 550 &first_pindex, &fs.first_prot, &fs.wired); 551 552 if (result != KERN_SUCCESS) { 553 *errorp = result; 554 return (NULL); 555 } 556 557 /* 558 * fs.map is read-locked 559 * 560 * Misc checks. Save the map generation number to detect races. 561 */ 562 fs.map_generation = fs.map->timestamp; 563 564 if (fs.entry->eflags & MAP_ENTRY_NOFAULT) { 565 panic("vm_fault: fault on nofault entry, addr: %lx", 566 (u_long)vaddr); 567 } 568 569 /* 570 * A system map entry may return a NULL object. No object means 571 * no pager means an unrecoverable kernel fault. 572 */ 573 if (fs.first_object == NULL) { 574 panic("vm_fault: unrecoverable fault at %p in entry %p", 575 (void *)vaddr, fs.entry); 576 } 577 578 /* 579 * Make a reference to this object to prevent its disposal while we 580 * are messing with it. Once we have the reference, the map is free 581 * to be diddled. Since objects reference their shadows (and copies), 582 * they will stay around as well. 583 * 584 * Bump the paging-in-progress count to prevent size changes (e.g. 585 * truncation operations) during I/O. This must be done after 586 * obtaining the vnode lock in order to avoid possible deadlocks. 587 * 588 * The vm_token is needed to manipulate the vm_object 589 */ 590 lwkt_gettoken(&vm_token); 591 vm_object_reference(fs.first_object); 592 fs.vp = vnode_pager_lock(fs.first_object); 593 vm_object_pip_add(fs.first_object, 1); 594 lwkt_reltoken(&vm_token); 595 596 fs.lookup_still_valid = TRUE; 597 fs.first_m = NULL; 598 fs.object = fs.first_object; /* so unlock_and_deallocate works */ 599 600 /* 601 * If the entry is wired we cannot change the page protection. 602 */ 603 if (fs.wired) 604 fault_type = fs.first_prot; 605 606 /* 607 * The page we want is at (first_object, first_pindex), but if the 608 * vm_map_entry is VM_MAPTYPE_VPAGETABLE we have to traverse the 609 * page table to figure out the actual pindex. 610 * 611 * NOTE! DEVELOPMENT IN PROGRESS, THIS IS AN INITIAL IMPLEMENTATION 612 * ONLY 613 */ 614 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) { 615 result = vm_fault_vpagetable(&fs, &first_pindex, 616 fs.entry->aux.master_pde, 617 fault_type); 618 if (result == KERN_TRY_AGAIN) 619 goto RetryFault; 620 if (result != KERN_SUCCESS) { 621 *errorp = result; 622 return (NULL); 623 } 624 } 625 626 /* 627 * Now we have the actual (object, pindex), fault in the page. If 628 * vm_fault_object() fails it will unlock and deallocate the FS 629 * data. If it succeeds everything remains locked and fs->object 630 * will have an additinal PIP count if it is not equal to 631 * fs->first_object 632 */ 633 result = vm_fault_object(&fs, first_pindex, fault_type); 634 635 if (result == KERN_TRY_AGAIN) 636 goto RetryFault; 637 if (result != KERN_SUCCESS) { 638 *errorp = result; 639 return(NULL); 640 } 641 642 if ((orig_fault_type & VM_PROT_WRITE) && 643 (fs.prot & VM_PROT_WRITE) == 0) { 644 *errorp = KERN_PROTECTION_FAILURE; 645 unlock_and_deallocate(&fs); 646 return(NULL); 647 } 648 649 /* 650 * On success vm_fault_object() does not unlock or deallocate, and fs.m 651 * will contain a busied page. 652 */ 653 unlock_things(&fs); 654 655 /* 656 * Return a held page. We are not doing any pmap manipulation so do 657 * not set PG_MAPPED. However, adjust the page flags according to 658 * the fault type because the caller may not use a managed pmapping 659 * (so we don't want to lose the fact that the page will be dirtied 660 * if a write fault was specified). 661 */ 662 lwkt_gettoken(&vm_token); 663 vm_page_hold(fs.m); 664 if (fault_type & VM_PROT_WRITE) 665 vm_page_dirty(fs.m); 666 667 /* 668 * Update the pmap. We really only have to do this if a COW 669 * occured to replace the read-only page with the new page. For 670 * now just do it unconditionally. XXX 671 */ 672 pmap_enter(fs.map->pmap, vaddr, fs.m, fs.prot, fs.wired); 673 vm_page_flag_set(fs.m, PG_REFERENCED); 674 675 /* 676 * Unbusy the page by activating it. It remains held and will not 677 * be reclaimed. 678 */ 679 vm_page_activate(fs.m); 680 681 if (curthread->td_lwp) { 682 if (fs.hardfault) { 683 curthread->td_lwp->lwp_ru.ru_majflt++; 684 } else { 685 curthread->td_lwp->lwp_ru.ru_minflt++; 686 } 687 } 688 689 /* 690 * Unlock everything, and return the held page. 691 */ 692 vm_page_wakeup(fs.m); 693 vm_object_deallocate(fs.first_object); 694 /*fs.first_object = NULL; */ 695 lwkt_reltoken(&vm_token); 696 697 *errorp = 0; 698 return(fs.m); 699 } 700 701 /* 702 * Fault in the specified (object,offset), dirty the returned page as 703 * needed. If the requested fault_type cannot be done NULL and an 704 * error is returned. 705 * 706 * A held (but not busied) page is returned. 707 * 708 * No requirements. 709 */ 710 vm_page_t 711 vm_fault_object_page(vm_object_t object, vm_ooffset_t offset, 712 vm_prot_t fault_type, int fault_flags, int *errorp) 713 { 714 int result; 715 vm_pindex_t first_pindex; 716 struct faultstate fs; 717 struct vm_map_entry entry; 718 719 bzero(&entry, sizeof(entry)); 720 entry.object.vm_object = object; 721 entry.maptype = VM_MAPTYPE_NORMAL; 722 entry.protection = entry.max_protection = fault_type; 723 724 fs.didlimit = 0; 725 fs.hardfault = 0; 726 fs.fault_flags = fault_flags; 727 fs.map = NULL; 728 KKASSERT((fault_flags & VM_FAULT_WIRE_MASK) == 0); 729 730 RetryFault: 731 732 fs.first_object = object; 733 first_pindex = OFF_TO_IDX(offset); 734 fs.entry = &entry; 735 fs.first_prot = fault_type; 736 fs.wired = 0; 737 /*fs.map_generation = 0; unused */ 738 739 /* 740 * Make a reference to this object to prevent its disposal while we 741 * are messing with it. Once we have the reference, the map is free 742 * to be diddled. Since objects reference their shadows (and copies), 743 * they will stay around as well. 744 * 745 * Bump the paging-in-progress count to prevent size changes (e.g. 746 * truncation operations) during I/O. This must be done after 747 * obtaining the vnode lock in order to avoid possible deadlocks. 748 */ 749 lwkt_gettoken(&vm_token); 750 vm_object_reference(fs.first_object); 751 fs.vp = vnode_pager_lock(fs.first_object); 752 vm_object_pip_add(fs.first_object, 1); 753 lwkt_reltoken(&vm_token); 754 755 fs.lookup_still_valid = TRUE; 756 fs.first_m = NULL; 757 fs.object = fs.first_object; /* so unlock_and_deallocate works */ 758 759 #if 0 760 /* XXX future - ability to operate on VM object using vpagetable */ 761 if (fs.entry->maptype == VM_MAPTYPE_VPAGETABLE) { 762 result = vm_fault_vpagetable(&fs, &first_pindex, 763 fs.entry->aux.master_pde, 764 fault_type); 765 if (result == KERN_TRY_AGAIN) 766 goto RetryFault; 767 if (result != KERN_SUCCESS) { 768 *errorp = result; 769 return (NULL); 770 } 771 } 772 #endif 773 774 /* 775 * Now we have the actual (object, pindex), fault in the page. If 776 * vm_fault_object() fails it will unlock and deallocate the FS 777 * data. If it succeeds everything remains locked and fs->object 778 * will have an additinal PIP count if it is not equal to 779 * fs->first_object 780 */ 781 result = vm_fault_object(&fs, first_pindex, fault_type); 782 783 if (result == KERN_TRY_AGAIN) 784 goto RetryFault; 785 if (result != KERN_SUCCESS) { 786 *errorp = result; 787 return(NULL); 788 } 789 790 if ((fault_type & VM_PROT_WRITE) && (fs.prot & VM_PROT_WRITE) == 0) { 791 *errorp = KERN_PROTECTION_FAILURE; 792 unlock_and_deallocate(&fs); 793 return(NULL); 794 } 795 796 /* 797 * On success vm_fault_object() does not unlock or deallocate, and fs.m 798 * will contain a busied page. 799 */ 800 unlock_things(&fs); 801 802 /* 803 * Return a held page. We are not doing any pmap manipulation so do 804 * not set PG_MAPPED. However, adjust the page flags according to 805 * the fault type because the caller may not use a managed pmapping 806 * (so we don't want to lose the fact that the page will be dirtied 807 * if a write fault was specified). 808 */ 809 lwkt_gettoken(&vm_token); 810 vm_page_hold(fs.m); 811 if (fault_type & VM_PROT_WRITE) 812 vm_page_dirty(fs.m); 813 814 if (fault_flags & VM_FAULT_DIRTY) 815 vm_page_dirty(fs.m); 816 if (fault_flags & VM_FAULT_UNSWAP) 817 swap_pager_unswapped(fs.m); 818 819 /* 820 * Indicate that the page was accessed. 821 */ 822 vm_page_flag_set(fs.m, PG_REFERENCED); 823 824 /* 825 * Unbusy the page by activating it. It remains held and will not 826 * be reclaimed. 827 */ 828 vm_page_activate(fs.m); 829 830 if (curthread->td_lwp) { 831 if (fs.hardfault) { 832 mycpu->gd_cnt.v_vm_faults++; 833 curthread->td_lwp->lwp_ru.ru_majflt++; 834 } else { 835 curthread->td_lwp->lwp_ru.ru_minflt++; 836 } 837 } 838 839 /* 840 * Unlock everything, and return the held page. 841 */ 842 vm_page_wakeup(fs.m); 843 vm_object_deallocate(fs.first_object); 844 /*fs.first_object = NULL; */ 845 lwkt_reltoken(&vm_token); 846 847 *errorp = 0; 848 return(fs.m); 849 } 850 851 /* 852 * Translate the virtual page number (first_pindex) that is relative 853 * to the address space into a logical page number that is relative to the 854 * backing object. Use the virtual page table pointed to by (vpte). 855 * 856 * This implements an N-level page table. Any level can terminate the 857 * scan by setting VPTE_PS. A linear mapping is accomplished by setting 858 * VPTE_PS in the master page directory entry set via mcontrol(MADV_SETMAP). 859 * 860 * No requirements (vm_token need not be held). 861 */ 862 static 863 int 864 vm_fault_vpagetable(struct faultstate *fs, vm_pindex_t *pindex, 865 vpte_t vpte, int fault_type) 866 { 867 struct lwbuf *lwb; 868 int vshift = VPTE_FRAME_END - PAGE_SHIFT; /* index bits remaining */ 869 int result = KERN_SUCCESS; 870 vpte_t *ptep; 871 872 for (;;) { 873 /* 874 * We cannot proceed if the vpte is not valid, not readable 875 * for a read fault, or not writable for a write fault. 876 */ 877 if ((vpte & VPTE_V) == 0) { 878 unlock_and_deallocate(fs); 879 return (KERN_FAILURE); 880 } 881 if ((fault_type & VM_PROT_READ) && (vpte & VPTE_R) == 0) { 882 unlock_and_deallocate(fs); 883 return (KERN_FAILURE); 884 } 885 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_W) == 0) { 886 unlock_and_deallocate(fs); 887 return (KERN_FAILURE); 888 } 889 if ((vpte & VPTE_PS) || vshift == 0) 890 break; 891 KKASSERT(vshift >= VPTE_PAGE_BITS); 892 893 /* 894 * Get the page table page. Nominally we only read the page 895 * table, but since we are actively setting VPTE_M and VPTE_A, 896 * tell vm_fault_object() that we are writing it. 897 * 898 * There is currently no real need to optimize this. 899 */ 900 result = vm_fault_object(fs, (vpte & VPTE_FRAME) >> PAGE_SHIFT, 901 VM_PROT_READ|VM_PROT_WRITE); 902 if (result != KERN_SUCCESS) 903 return (result); 904 905 /* 906 * Process the returned fs.m and look up the page table 907 * entry in the page table page. 908 */ 909 vshift -= VPTE_PAGE_BITS; 910 lwb = lwbuf_alloc(fs->m); 911 ptep = ((vpte_t *)lwbuf_kva(lwb) + 912 ((*pindex >> vshift) & VPTE_PAGE_MASK)); 913 vpte = *ptep; 914 915 /* 916 * Page table write-back. If the vpte is valid for the 917 * requested operation, do a write-back to the page table. 918 * 919 * XXX VPTE_M is not set properly for page directory pages. 920 * It doesn't get set in the page directory if the page table 921 * is modified during a read access. 922 */ 923 if ((fault_type & VM_PROT_WRITE) && (vpte & VPTE_V) && 924 (vpte & VPTE_W)) { 925 if ((vpte & (VPTE_M|VPTE_A)) != (VPTE_M|VPTE_A)) { 926 atomic_set_long(ptep, VPTE_M | VPTE_A); 927 vm_page_dirty(fs->m); 928 } 929 } 930 if ((fault_type & VM_PROT_READ) && (vpte & VPTE_V) && 931 (vpte & VPTE_R)) { 932 if ((vpte & VPTE_A) == 0) { 933 atomic_set_long(ptep, VPTE_A); 934 vm_page_dirty(fs->m); 935 } 936 } 937 lwbuf_free(lwb); 938 vm_page_flag_set(fs->m, PG_REFERENCED); 939 vm_page_activate(fs->m); 940 vm_page_wakeup(fs->m); 941 fs->m = NULL; 942 cleanup_successful_fault(fs); 943 } 944 /* 945 * Combine remaining address bits with the vpte. 946 */ 947 /* JG how many bits from each? */ 948 *pindex = ((vpte & VPTE_FRAME) >> PAGE_SHIFT) + 949 (*pindex & ((1L << vshift) - 1)); 950 return (KERN_SUCCESS); 951 } 952 953 954 /* 955 * This is the core of the vm_fault code. 956 * 957 * Do all operations required to fault-in (fs.first_object, pindex). Run 958 * through the shadow chain as necessary and do required COW or virtual 959 * copy operations. The caller has already fully resolved the vm_map_entry 960 * and, if appropriate, has created a copy-on-write layer. All we need to 961 * do is iterate the object chain. 962 * 963 * On failure (fs) is unlocked and deallocated and the caller may return or 964 * retry depending on the failure code. On success (fs) is NOT unlocked or 965 * deallocated, fs.m will contained a resolved, busied page, and fs.object 966 * will have an additional PIP count if it is not equal to fs.first_object. 967 * 968 * No requirements. 969 */ 970 static 971 int 972 vm_fault_object(struct faultstate *fs, 973 vm_pindex_t first_pindex, vm_prot_t fault_type) 974 { 975 vm_object_t next_object; 976 vm_pindex_t pindex; 977 978 fs->prot = fs->first_prot; 979 fs->object = fs->first_object; 980 pindex = first_pindex; 981 982 /* 983 * If a read fault occurs we try to make the page writable if 984 * possible. There are three cases where we cannot make the 985 * page mapping writable: 986 * 987 * (1) The mapping is read-only or the VM object is read-only, 988 * fs->prot above will simply not have VM_PROT_WRITE set. 989 * 990 * (2) If the mapping is a virtual page table we need to be able 991 * to detect writes so we can set VPTE_M in the virtual page 992 * table. 993 * 994 * (3) If the VM page is read-only or copy-on-write, upgrading would 995 * just result in an unnecessary COW fault. 996 * 997 * VM_PROT_VPAGED is set if faulting via a virtual page table and 998 * causes adjustments to the 'M'odify bit to also turn off write 999 * access to force a re-fault. 1000 */ 1001 if (fs->entry->maptype == VM_MAPTYPE_VPAGETABLE) { 1002 if ((fault_type & VM_PROT_WRITE) == 0) 1003 fs->prot &= ~VM_PROT_WRITE; 1004 } 1005 1006 lwkt_gettoken(&vm_token); 1007 1008 for (;;) { 1009 /* 1010 * If the object is dead, we stop here 1011 */ 1012 if (fs->object->flags & OBJ_DEAD) { 1013 unlock_and_deallocate(fs); 1014 lwkt_reltoken(&vm_token); 1015 return (KERN_PROTECTION_FAILURE); 1016 } 1017 1018 /* 1019 * See if the page is resident. 1020 */ 1021 fs->m = vm_page_lookup(fs->object, pindex); 1022 if (fs->m != NULL) { 1023 int queue; 1024 /* 1025 * Wait/Retry if the page is busy. We have to do this 1026 * if the page is busy via either PG_BUSY or 1027 * vm_page_t->busy because the vm_pager may be using 1028 * vm_page_t->busy for pageouts ( and even pageins if 1029 * it is the vnode pager ), and we could end up trying 1030 * to pagein and pageout the same page simultaneously. 1031 * 1032 * We can theoretically allow the busy case on a read 1033 * fault if the page is marked valid, but since such 1034 * pages are typically already pmap'd, putting that 1035 * special case in might be more effort then it is 1036 * worth. We cannot under any circumstances mess 1037 * around with a vm_page_t->busy page except, perhaps, 1038 * to pmap it. 1039 */ 1040 if ((fs->m->flags & PG_BUSY) || fs->m->busy) { 1041 unlock_things(fs); 1042 vm_page_sleep_busy(fs->m, TRUE, "vmpfw"); 1043 mycpu->gd_cnt.v_intrans++; 1044 vm_object_deallocate(fs->first_object); 1045 fs->first_object = NULL; 1046 lwkt_reltoken(&vm_token); 1047 return (KERN_TRY_AGAIN); 1048 } 1049 1050 /* 1051 * If reactivating a page from PQ_CACHE we may have 1052 * to rate-limit. 1053 */ 1054 queue = fs->m->queue; 1055 vm_page_unqueue_nowakeup(fs->m); 1056 1057 if ((queue - fs->m->pc) == PQ_CACHE && 1058 vm_page_count_severe()) { 1059 vm_page_activate(fs->m); 1060 unlock_and_deallocate(fs); 1061 vm_waitpfault(); 1062 lwkt_reltoken(&vm_token); 1063 return (KERN_TRY_AGAIN); 1064 } 1065 1066 /* 1067 * Mark page busy for other processes, and the 1068 * pagedaemon. If it still isn't completely valid 1069 * (readable), or if a read-ahead-mark is set on 1070 * the VM page, jump to readrest, else we found the 1071 * page and can return. 1072 * 1073 * We can release the spl once we have marked the 1074 * page busy. 1075 */ 1076 vm_page_busy(fs->m); 1077 1078 if (fs->m->object != &kernel_object) { 1079 if ((fs->m->valid & VM_PAGE_BITS_ALL) != 1080 VM_PAGE_BITS_ALL) { 1081 goto readrest; 1082 } 1083 if (fs->m->flags & PG_RAM) { 1084 if (debug_cluster) 1085 kprintf("R"); 1086 vm_page_flag_clear(fs->m, PG_RAM); 1087 goto readrest; 1088 } 1089 } 1090 break; /* break to PAGE HAS BEEN FOUND */ 1091 } 1092 1093 /* 1094 * Page is not resident, If this is the search termination 1095 * or the pager might contain the page, allocate a new page. 1096 */ 1097 if (TRYPAGER(fs) || fs->object == fs->first_object) { 1098 /* 1099 * If the page is beyond the object size we fail 1100 */ 1101 if (pindex >= fs->object->size) { 1102 lwkt_reltoken(&vm_token); 1103 unlock_and_deallocate(fs); 1104 return (KERN_PROTECTION_FAILURE); 1105 } 1106 1107 /* 1108 * Ratelimit. 1109 */ 1110 if (fs->didlimit == 0 && curproc != NULL) { 1111 int limticks; 1112 1113 limticks = vm_fault_ratelimit(curproc->p_vmspace); 1114 if (limticks) { 1115 lwkt_reltoken(&vm_token); 1116 unlock_and_deallocate(fs); 1117 tsleep(curproc, 0, "vmrate", limticks); 1118 fs->didlimit = 1; 1119 return (KERN_TRY_AGAIN); 1120 } 1121 } 1122 1123 /* 1124 * Allocate a new page for this object/offset pair. 1125 */ 1126 fs->m = NULL; 1127 if (!vm_page_count_severe()) { 1128 fs->m = vm_page_alloc(fs->object, pindex, 1129 (fs->vp || fs->object->backing_object) ? VM_ALLOC_NORMAL : VM_ALLOC_NORMAL | VM_ALLOC_ZERO); 1130 } 1131 if (fs->m == NULL) { 1132 lwkt_reltoken(&vm_token); 1133 unlock_and_deallocate(fs); 1134 vm_waitpfault(); 1135 return (KERN_TRY_AGAIN); 1136 } 1137 } 1138 1139 readrest: 1140 /* 1141 * We have found an invalid or partially valid page, a 1142 * page with a read-ahead mark which might be partially or 1143 * fully valid (and maybe dirty too), or we have allocated 1144 * a new page. 1145 * 1146 * Attempt to fault-in the page if there is a chance that the 1147 * pager has it, and potentially fault in additional pages 1148 * at the same time. 1149 * 1150 * We are NOT in splvm here and if TRYPAGER is true then 1151 * fs.m will be non-NULL and will be PG_BUSY for us. 1152 */ 1153 if (TRYPAGER(fs)) { 1154 int rv; 1155 int seqaccess; 1156 u_char behavior = vm_map_entry_behavior(fs->entry); 1157 1158 if (behavior == MAP_ENTRY_BEHAV_RANDOM) 1159 seqaccess = 0; 1160 else 1161 seqaccess = -1; 1162 1163 /* 1164 * If sequential access is detected then attempt 1165 * to deactivate/cache pages behind the scan to 1166 * prevent resource hogging. 1167 * 1168 * Use of PG_RAM to detect sequential access 1169 * also simulates multi-zone sequential access 1170 * detection for free. 1171 * 1172 * NOTE: Partially valid dirty pages cannot be 1173 * deactivated without causing NFS picemeal 1174 * writes to barf. 1175 */ 1176 if ((fs->first_object->type != OBJT_DEVICE) && 1177 (behavior == MAP_ENTRY_BEHAV_SEQUENTIAL || 1178 (behavior != MAP_ENTRY_BEHAV_RANDOM && 1179 (fs->m->flags & PG_RAM))) 1180 ) { 1181 vm_pindex_t scan_pindex; 1182 int scan_count = 16; 1183 1184 if (first_pindex < 16) { 1185 scan_pindex = 0; 1186 scan_count = 0; 1187 } else { 1188 scan_pindex = first_pindex - 16; 1189 if (scan_pindex < 16) 1190 scan_count = scan_pindex; 1191 else 1192 scan_count = 16; 1193 } 1194 1195 while (scan_count) { 1196 vm_page_t mt; 1197 1198 mt = vm_page_lookup(fs->first_object, 1199 scan_pindex); 1200 if (mt == NULL || 1201 (mt->valid != VM_PAGE_BITS_ALL)) { 1202 break; 1203 } 1204 if (mt->busy || 1205 (mt->flags & (PG_BUSY | PG_FICTITIOUS | PG_UNMANAGED)) || 1206 mt->hold_count || 1207 mt->wire_count) { 1208 goto skip; 1209 } 1210 vm_page_busy(mt); 1211 if (mt->dirty == 0) 1212 vm_page_test_dirty(mt); 1213 if (mt->dirty) { 1214 vm_page_protect(mt, 1215 VM_PROT_NONE); 1216 vm_page_deactivate(mt); 1217 vm_page_wakeup(mt); 1218 } else { 1219 vm_page_cache(mt); 1220 } 1221 skip: 1222 --scan_count; 1223 --scan_pindex; 1224 } 1225 1226 seqaccess = 1; 1227 } 1228 1229 /* 1230 * Avoid deadlocking against the map when doing I/O. 1231 * fs.object and the page is PG_BUSY'd. 1232 */ 1233 unlock_map(fs); 1234 1235 /* 1236 * Acquire the page data. We still hold a ref on 1237 * fs.object and the page has been PG_BUSY's. 1238 * 1239 * The pager may replace the page (for example, in 1240 * order to enter a fictitious page into the 1241 * object). If it does so it is responsible for 1242 * cleaning up the passed page and properly setting 1243 * the new page PG_BUSY. 1244 * 1245 * If we got here through a PG_RAM read-ahead 1246 * mark the page may be partially dirty and thus 1247 * not freeable. Don't bother checking to see 1248 * if the pager has the page because we can't free 1249 * it anyway. We have to depend on the get_page 1250 * operation filling in any gaps whether there is 1251 * backing store or not. 1252 */ 1253 rv = vm_pager_get_page(fs->object, &fs->m, seqaccess); 1254 1255 if (rv == VM_PAGER_OK) { 1256 /* 1257 * Relookup in case pager changed page. Pager 1258 * is responsible for disposition of old page 1259 * if moved. 1260 * 1261 * XXX other code segments do relookups too. 1262 * It's a bad abstraction that needs to be 1263 * fixed/removed. 1264 */ 1265 fs->m = vm_page_lookup(fs->object, pindex); 1266 if (fs->m == NULL) { 1267 lwkt_reltoken(&vm_token); 1268 unlock_and_deallocate(fs); 1269 return (KERN_TRY_AGAIN); 1270 } 1271 1272 ++fs->hardfault; 1273 break; /* break to PAGE HAS BEEN FOUND */ 1274 } 1275 1276 /* 1277 * Remove the bogus page (which does not exist at this 1278 * object/offset); before doing so, we must get back 1279 * our object lock to preserve our invariant. 1280 * 1281 * Also wake up any other process that may want to bring 1282 * in this page. 1283 * 1284 * If this is the top-level object, we must leave the 1285 * busy page to prevent another process from rushing 1286 * past us, and inserting the page in that object at 1287 * the same time that we are. 1288 */ 1289 if (rv == VM_PAGER_ERROR) { 1290 if (curproc) 1291 kprintf("vm_fault: pager read error, pid %d (%s)\n", curproc->p_pid, curproc->p_comm); 1292 else 1293 kprintf("vm_fault: pager read error, thread %p (%s)\n", curthread, curproc->p_comm); 1294 } 1295 1296 /* 1297 * Data outside the range of the pager or an I/O error 1298 * 1299 * The page may have been wired during the pagein, 1300 * e.g. by the buffer cache, and cannot simply be 1301 * freed. Call vnode_pager_freepage() to deal with it. 1302 */ 1303 /* 1304 * XXX - the check for kernel_map is a kludge to work 1305 * around having the machine panic on a kernel space 1306 * fault w/ I/O error. 1307 */ 1308 if (((fs->map != &kernel_map) && 1309 (rv == VM_PAGER_ERROR)) || (rv == VM_PAGER_BAD)) { 1310 vnode_pager_freepage(fs->m); 1311 lwkt_reltoken(&vm_token); 1312 fs->m = NULL; 1313 unlock_and_deallocate(fs); 1314 if (rv == VM_PAGER_ERROR) 1315 return (KERN_FAILURE); 1316 else 1317 return (KERN_PROTECTION_FAILURE); 1318 /* NOT REACHED */ 1319 } 1320 if (fs->object != fs->first_object) { 1321 vnode_pager_freepage(fs->m); 1322 fs->m = NULL; 1323 /* 1324 * XXX - we cannot just fall out at this 1325 * point, m has been freed and is invalid! 1326 */ 1327 } 1328 } 1329 1330 /* 1331 * We get here if the object has a default pager (or unwiring) 1332 * or the pager doesn't have the page. 1333 */ 1334 if (fs->object == fs->first_object) 1335 fs->first_m = fs->m; 1336 1337 /* 1338 * Move on to the next object. Lock the next object before 1339 * unlocking the current one. 1340 */ 1341 pindex += OFF_TO_IDX(fs->object->backing_object_offset); 1342 next_object = fs->object->backing_object; 1343 if (next_object == NULL) { 1344 /* 1345 * If there's no object left, fill the page in the top 1346 * object with zeros. 1347 */ 1348 if (fs->object != fs->first_object) { 1349 vm_object_pip_wakeup(fs->object); 1350 1351 fs->object = fs->first_object; 1352 pindex = first_pindex; 1353 fs->m = fs->first_m; 1354 } 1355 fs->first_m = NULL; 1356 1357 /* 1358 * Zero the page if necessary and mark it valid. 1359 */ 1360 if ((fs->m->flags & PG_ZERO) == 0) { 1361 vm_page_zero_fill(fs->m); 1362 } else { 1363 #ifdef PMAP_DEBUG 1364 pmap_page_assertzero(VM_PAGE_TO_PHYS(fs->m)); 1365 #endif 1366 vm_page_flag_clear(fs->m, PG_ZERO); 1367 mycpu->gd_cnt.v_ozfod++; 1368 } 1369 mycpu->gd_cnt.v_zfod++; 1370 fs->m->valid = VM_PAGE_BITS_ALL; 1371 break; /* break to PAGE HAS BEEN FOUND */ 1372 } 1373 if (fs->object != fs->first_object) { 1374 vm_object_pip_wakeup(fs->object); 1375 } 1376 KASSERT(fs->object != next_object, 1377 ("object loop %p", next_object)); 1378 fs->object = next_object; 1379 vm_object_pip_add(fs->object, 1); 1380 } 1381 1382 /* 1383 * PAGE HAS BEEN FOUND. [Loop invariant still holds -- the object lock 1384 * is held.] 1385 * 1386 * vm_token is still held 1387 * 1388 * If the page is being written, but isn't already owned by the 1389 * top-level object, we have to copy it into a new page owned by the 1390 * top-level object. 1391 */ 1392 KASSERT((fs->m->flags & PG_BUSY) != 0, 1393 ("vm_fault: not busy after main loop")); 1394 1395 if (fs->object != fs->first_object) { 1396 /* 1397 * We only really need to copy if we want to write it. 1398 */ 1399 if (fault_type & VM_PROT_WRITE) { 1400 /* 1401 * This allows pages to be virtually copied from a 1402 * backing_object into the first_object, where the 1403 * backing object has no other refs to it, and cannot 1404 * gain any more refs. Instead of a bcopy, we just 1405 * move the page from the backing object to the 1406 * first object. Note that we must mark the page 1407 * dirty in the first object so that it will go out 1408 * to swap when needed. 1409 */ 1410 if ( 1411 /* 1412 * Map, if present, has not changed 1413 */ 1414 (fs->map == NULL || 1415 fs->map_generation == fs->map->timestamp) && 1416 /* 1417 * Only one shadow object 1418 */ 1419 (fs->object->shadow_count == 1) && 1420 /* 1421 * No COW refs, except us 1422 */ 1423 (fs->object->ref_count == 1) && 1424 /* 1425 * No one else can look this object up 1426 */ 1427 (fs->object->handle == NULL) && 1428 /* 1429 * No other ways to look the object up 1430 */ 1431 ((fs->object->type == OBJT_DEFAULT) || 1432 (fs->object->type == OBJT_SWAP)) && 1433 /* 1434 * We don't chase down the shadow chain 1435 */ 1436 (fs->object == fs->first_object->backing_object) && 1437 1438 /* 1439 * grab the lock if we need to 1440 */ 1441 (fs->lookup_still_valid || 1442 fs->map == NULL || 1443 lockmgr(&fs->map->lock, LK_EXCLUSIVE|LK_NOWAIT) == 0) 1444 ) { 1445 1446 fs->lookup_still_valid = 1; 1447 /* 1448 * get rid of the unnecessary page 1449 */ 1450 vm_page_protect(fs->first_m, VM_PROT_NONE); 1451 vm_page_free(fs->first_m); 1452 fs->first_m = NULL; 1453 1454 /* 1455 * grab the page and put it into the 1456 * process'es object. The page is 1457 * automatically made dirty. 1458 */ 1459 vm_page_rename(fs->m, fs->first_object, first_pindex); 1460 fs->first_m = fs->m; 1461 vm_page_busy(fs->first_m); 1462 fs->m = NULL; 1463 mycpu->gd_cnt.v_cow_optim++; 1464 } else { 1465 /* 1466 * Oh, well, lets copy it. 1467 */ 1468 vm_page_copy(fs->m, fs->first_m); 1469 vm_page_event(fs->m, VMEVENT_COW); 1470 } 1471 1472 if (fs->m) { 1473 /* 1474 * We no longer need the old page or object. 1475 */ 1476 release_page(fs); 1477 } 1478 1479 /* 1480 * fs->object != fs->first_object due to above 1481 * conditional 1482 */ 1483 vm_object_pip_wakeup(fs->object); 1484 1485 /* 1486 * Only use the new page below... 1487 */ 1488 1489 mycpu->gd_cnt.v_cow_faults++; 1490 fs->m = fs->first_m; 1491 fs->object = fs->first_object; 1492 pindex = first_pindex; 1493 } else { 1494 /* 1495 * If it wasn't a write fault avoid having to copy 1496 * the page by mapping it read-only. 1497 */ 1498 fs->prot &= ~VM_PROT_WRITE; 1499 } 1500 } 1501 1502 /* 1503 * We may have had to unlock a map to do I/O. If we did then 1504 * lookup_still_valid will be FALSE. If the map generation count 1505 * also changed then all sorts of things could have happened while 1506 * we were doing the I/O and we need to retry. 1507 */ 1508 1509 if (!fs->lookup_still_valid && 1510 fs->map != NULL && 1511 (fs->map->timestamp != fs->map_generation)) { 1512 release_page(fs); 1513 lwkt_reltoken(&vm_token); 1514 unlock_and_deallocate(fs); 1515 return (KERN_TRY_AGAIN); 1516 } 1517 1518 /* 1519 * If the fault is a write, we know that this page is being 1520 * written NOW so dirty it explicitly to save on pmap_is_modified() 1521 * calls later. 1522 * 1523 * If this is a NOSYNC mmap we do not want to set PG_NOSYNC 1524 * if the page is already dirty to prevent data written with 1525 * the expectation of being synced from not being synced. 1526 * Likewise if this entry does not request NOSYNC then make 1527 * sure the page isn't marked NOSYNC. Applications sharing 1528 * data should use the same flags to avoid ping ponging. 1529 * 1530 * Also tell the backing pager, if any, that it should remove 1531 * any swap backing since the page is now dirty. 1532 */ 1533 if (fs->prot & VM_PROT_WRITE) { 1534 vm_object_set_writeable_dirty(fs->m->object); 1535 vm_set_nosync(fs->m, fs->entry); 1536 if (fs->fault_flags & VM_FAULT_DIRTY) { 1537 vm_page_dirty(fs->m); 1538 swap_pager_unswapped(fs->m); 1539 } 1540 } 1541 1542 lwkt_reltoken(&vm_token); 1543 1544 /* 1545 * Page had better still be busy. We are still locked up and 1546 * fs->object will have another PIP reference if it is not equal 1547 * to fs->first_object. 1548 */ 1549 KASSERT(fs->m->flags & PG_BUSY, 1550 ("vm_fault: page %p not busy!", fs->m)); 1551 1552 /* 1553 * Sanity check: page must be completely valid or it is not fit to 1554 * map into user space. vm_pager_get_pages() ensures this. 1555 */ 1556 if (fs->m->valid != VM_PAGE_BITS_ALL) { 1557 vm_page_zero_invalid(fs->m, TRUE); 1558 kprintf("Warning: page %p partially invalid on fault\n", fs->m); 1559 } 1560 vm_page_flag_clear(fs->m, PG_ZERO); 1561 1562 return (KERN_SUCCESS); 1563 } 1564 1565 /* 1566 * Wire down a range of virtual addresses in a map. The entry in question 1567 * should be marked in-transition and the map must be locked. We must 1568 * release the map temporarily while faulting-in the page to avoid a 1569 * deadlock. Note that the entry may be clipped while we are blocked but 1570 * will never be freed. 1571 * 1572 * No requirements. 1573 */ 1574 int 1575 vm_fault_wire(vm_map_t map, vm_map_entry_t entry, boolean_t user_wire) 1576 { 1577 boolean_t fictitious; 1578 vm_offset_t start; 1579 vm_offset_t end; 1580 vm_offset_t va; 1581 vm_paddr_t pa; 1582 pmap_t pmap; 1583 int rv; 1584 1585 pmap = vm_map_pmap(map); 1586 start = entry->start; 1587 end = entry->end; 1588 fictitious = entry->object.vm_object && 1589 (entry->object.vm_object->type == OBJT_DEVICE); 1590 if (entry->eflags & MAP_ENTRY_KSTACK) 1591 start += PAGE_SIZE; 1592 lwkt_gettoken(&vm_token); 1593 vm_map_unlock(map); 1594 map->timestamp++; 1595 1596 /* 1597 * We simulate a fault to get the page and enter it in the physical 1598 * map. 1599 */ 1600 for (va = start; va < end; va += PAGE_SIZE) { 1601 if (user_wire) { 1602 rv = vm_fault(map, va, VM_PROT_READ, 1603 VM_FAULT_USER_WIRE); 1604 } else { 1605 rv = vm_fault(map, va, VM_PROT_READ|VM_PROT_WRITE, 1606 VM_FAULT_CHANGE_WIRING); 1607 } 1608 if (rv) { 1609 while (va > start) { 1610 va -= PAGE_SIZE; 1611 if ((pa = pmap_extract(pmap, va)) == 0) 1612 continue; 1613 pmap_change_wiring(pmap, va, FALSE); 1614 if (!fictitious) 1615 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1); 1616 } 1617 vm_map_lock(map); 1618 lwkt_reltoken(&vm_token); 1619 return (rv); 1620 } 1621 } 1622 vm_map_lock(map); 1623 lwkt_reltoken(&vm_token); 1624 return (KERN_SUCCESS); 1625 } 1626 1627 /* 1628 * Unwire a range of virtual addresses in a map. The map should be 1629 * locked. 1630 */ 1631 void 1632 vm_fault_unwire(vm_map_t map, vm_map_entry_t entry) 1633 { 1634 boolean_t fictitious; 1635 vm_offset_t start; 1636 vm_offset_t end; 1637 vm_offset_t va; 1638 vm_paddr_t pa; 1639 pmap_t pmap; 1640 1641 pmap = vm_map_pmap(map); 1642 start = entry->start; 1643 end = entry->end; 1644 fictitious = entry->object.vm_object && 1645 (entry->object.vm_object->type == OBJT_DEVICE); 1646 if (entry->eflags & MAP_ENTRY_KSTACK) 1647 start += PAGE_SIZE; 1648 1649 /* 1650 * Since the pages are wired down, we must be able to get their 1651 * mappings from the physical map system. 1652 */ 1653 lwkt_gettoken(&vm_token); 1654 for (va = start; va < end; va += PAGE_SIZE) { 1655 pa = pmap_extract(pmap, va); 1656 if (pa != 0) { 1657 pmap_change_wiring(pmap, va, FALSE); 1658 if (!fictitious) 1659 vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1); 1660 } 1661 } 1662 lwkt_reltoken(&vm_token); 1663 } 1664 1665 /* 1666 * Reduce the rate at which memory is allocated to a process based 1667 * on the perceived load on the VM system. As the load increases 1668 * the allocation burst rate goes down and the delay increases. 1669 * 1670 * Rate limiting does not apply when faulting active or inactive 1671 * pages. When faulting 'cache' pages, rate limiting only applies 1672 * if the system currently has a severe page deficit. 1673 * 1674 * XXX vm_pagesupply should be increased when a page is freed. 1675 * 1676 * We sleep up to 1/10 of a second. 1677 */ 1678 static int 1679 vm_fault_ratelimit(struct vmspace *vmspace) 1680 { 1681 if (vm_load_enable == 0) 1682 return(0); 1683 if (vmspace->vm_pagesupply > 0) { 1684 --vmspace->vm_pagesupply; /* SMP race ok */ 1685 return(0); 1686 } 1687 #ifdef INVARIANTS 1688 if (vm_load_debug) { 1689 kprintf("load %-4d give %d pgs, wait %d, pid %-5d (%s)\n", 1690 vm_load, 1691 (1000 - vm_load ) / 10, vm_load * hz / 10000, 1692 curproc->p_pid, curproc->p_comm); 1693 } 1694 #endif 1695 vmspace->vm_pagesupply = (1000 - vm_load) / 10; 1696 return(vm_load * hz / 10000); 1697 } 1698 1699 /* 1700 * Copy all of the pages from a wired-down map entry to another. 1701 * 1702 * The source and destination maps must be locked for write. 1703 * The source map entry must be wired down (or be a sharing map 1704 * entry corresponding to a main map entry that is wired down). 1705 * 1706 * No other requirements. 1707 */ 1708 void 1709 vm_fault_copy_entry(vm_map_t dst_map, vm_map_t src_map, 1710 vm_map_entry_t dst_entry, vm_map_entry_t src_entry) 1711 { 1712 vm_object_t dst_object; 1713 vm_object_t src_object; 1714 vm_ooffset_t dst_offset; 1715 vm_ooffset_t src_offset; 1716 vm_prot_t prot; 1717 vm_offset_t vaddr; 1718 vm_page_t dst_m; 1719 vm_page_t src_m; 1720 1721 #ifdef lint 1722 src_map++; 1723 #endif /* lint */ 1724 1725 src_object = src_entry->object.vm_object; 1726 src_offset = src_entry->offset; 1727 1728 /* 1729 * Create the top-level object for the destination entry. (Doesn't 1730 * actually shadow anything - we copy the pages directly.) 1731 */ 1732 vm_map_entry_allocate_object(dst_entry); 1733 dst_object = dst_entry->object.vm_object; 1734 1735 prot = dst_entry->max_protection; 1736 1737 /* 1738 * Loop through all of the pages in the entry's range, copying each 1739 * one from the source object (it should be there) to the destination 1740 * object. 1741 */ 1742 for (vaddr = dst_entry->start, dst_offset = 0; 1743 vaddr < dst_entry->end; 1744 vaddr += PAGE_SIZE, dst_offset += PAGE_SIZE) { 1745 1746 /* 1747 * Allocate a page in the destination object 1748 */ 1749 do { 1750 dst_m = vm_page_alloc(dst_object, 1751 OFF_TO_IDX(dst_offset), VM_ALLOC_NORMAL); 1752 if (dst_m == NULL) { 1753 vm_wait(0); 1754 } 1755 } while (dst_m == NULL); 1756 1757 /* 1758 * Find the page in the source object, and copy it in. 1759 * (Because the source is wired down, the page will be in 1760 * memory.) 1761 */ 1762 src_m = vm_page_lookup(src_object, 1763 OFF_TO_IDX(dst_offset + src_offset)); 1764 if (src_m == NULL) 1765 panic("vm_fault_copy_wired: page missing"); 1766 1767 vm_page_copy(src_m, dst_m); 1768 vm_page_event(src_m, VMEVENT_COW); 1769 1770 /* 1771 * Enter it in the pmap... 1772 */ 1773 1774 vm_page_flag_clear(dst_m, PG_ZERO); 1775 pmap_enter(dst_map->pmap, vaddr, dst_m, prot, FALSE); 1776 1777 /* 1778 * Mark it no longer busy, and put it on the active list. 1779 */ 1780 vm_page_activate(dst_m); 1781 vm_page_wakeup(dst_m); 1782 } 1783 } 1784 1785 #if 0 1786 1787 /* 1788 * This routine checks around the requested page for other pages that 1789 * might be able to be faulted in. This routine brackets the viable 1790 * pages for the pages to be paged in. 1791 * 1792 * Inputs: 1793 * m, rbehind, rahead 1794 * 1795 * Outputs: 1796 * marray (array of vm_page_t), reqpage (index of requested page) 1797 * 1798 * Return value: 1799 * number of pages in marray 1800 */ 1801 static int 1802 vm_fault_additional_pages(vm_page_t m, int rbehind, int rahead, 1803 vm_page_t *marray, int *reqpage) 1804 { 1805 int i,j; 1806 vm_object_t object; 1807 vm_pindex_t pindex, startpindex, endpindex, tpindex; 1808 vm_page_t rtm; 1809 int cbehind, cahead; 1810 1811 object = m->object; 1812 pindex = m->pindex; 1813 1814 /* 1815 * we don't fault-ahead for device pager 1816 */ 1817 if (object->type == OBJT_DEVICE) { 1818 *reqpage = 0; 1819 marray[0] = m; 1820 return 1; 1821 } 1822 1823 /* 1824 * if the requested page is not available, then give up now 1825 */ 1826 if (!vm_pager_has_page(object, pindex, &cbehind, &cahead)) { 1827 *reqpage = 0; /* not used by caller, fix compiler warn */ 1828 return 0; 1829 } 1830 1831 if ((cbehind == 0) && (cahead == 0)) { 1832 *reqpage = 0; 1833 marray[0] = m; 1834 return 1; 1835 } 1836 1837 if (rahead > cahead) { 1838 rahead = cahead; 1839 } 1840 1841 if (rbehind > cbehind) { 1842 rbehind = cbehind; 1843 } 1844 1845 /* 1846 * Do not do any readahead if we have insufficient free memory. 1847 * 1848 * XXX code was broken disabled before and has instability 1849 * with this conditonal fixed, so shortcut for now. 1850 */ 1851 if (burst_fault == 0 || vm_page_count_severe()) { 1852 marray[0] = m; 1853 *reqpage = 0; 1854 return 1; 1855 } 1856 1857 /* 1858 * scan backward for the read behind pages -- in memory 1859 * 1860 * Assume that if the page is not found an interrupt will not 1861 * create it. Theoretically interrupts can only remove (busy) 1862 * pages, not create new associations. 1863 */ 1864 if (pindex > 0) { 1865 if (rbehind > pindex) { 1866 rbehind = pindex; 1867 startpindex = 0; 1868 } else { 1869 startpindex = pindex - rbehind; 1870 } 1871 1872 lwkt_gettoken(&vm_token); 1873 for (tpindex = pindex; tpindex > startpindex; --tpindex) { 1874 if (vm_page_lookup(object, tpindex - 1)) 1875 break; 1876 } 1877 1878 i = 0; 1879 while (tpindex < pindex) { 1880 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM); 1881 if (rtm == NULL) { 1882 lwkt_reltoken(&vm_token); 1883 for (j = 0; j < i; j++) { 1884 vm_page_free(marray[j]); 1885 } 1886 marray[0] = m; 1887 *reqpage = 0; 1888 return 1; 1889 } 1890 marray[i] = rtm; 1891 ++i; 1892 ++tpindex; 1893 } 1894 lwkt_reltoken(&vm_token); 1895 } else { 1896 i = 0; 1897 } 1898 1899 /* 1900 * Assign requested page 1901 */ 1902 marray[i] = m; 1903 *reqpage = i; 1904 ++i; 1905 1906 /* 1907 * Scan forwards for read-ahead pages 1908 */ 1909 tpindex = pindex + 1; 1910 endpindex = tpindex + rahead; 1911 if (endpindex > object->size) 1912 endpindex = object->size; 1913 1914 lwkt_gettoken(&vm_token); 1915 while (tpindex < endpindex) { 1916 if (vm_page_lookup(object, tpindex)) 1917 break; 1918 rtm = vm_page_alloc(object, tpindex, VM_ALLOC_SYSTEM); 1919 if (rtm == NULL) 1920 break; 1921 marray[i] = rtm; 1922 ++i; 1923 ++tpindex; 1924 } 1925 lwkt_reltoken(&vm_token); 1926 1927 return (i); 1928 } 1929 1930 #endif 1931 1932 /* 1933 * vm_prefault() provides a quick way of clustering pagefaults into a 1934 * processes address space. It is a "cousin" of pmap_object_init_pt, 1935 * except it runs at page fault time instead of mmap time. 1936 * 1937 * This code used to be per-platform pmap_prefault(). It is now 1938 * machine-independent and enhanced to also pre-fault zero-fill pages 1939 * (see vm.fast_fault) as well as make them writable, which greatly 1940 * reduces the number of page faults programs incur. 1941 * 1942 * Application performance when pre-faulting zero-fill pages is heavily 1943 * dependent on the application. Very tiny applications like /bin/echo 1944 * lose a little performance while applications of any appreciable size 1945 * gain performance. Prefaulting multiple pages also reduces SMP 1946 * congestion and can improve SMP performance significantly. 1947 * 1948 * NOTE! prot may allow writing but this only applies to the top level 1949 * object. If we wind up mapping a page extracted from a backing 1950 * object we have to make sure it is read-only. 1951 * 1952 * NOTE! The caller has already handled any COW operations on the 1953 * vm_map_entry via the normal fault code. Do NOT call this 1954 * shortcut unless the normal fault code has run on this entry. 1955 * 1956 * No other requirements. 1957 */ 1958 #define PFBAK 4 1959 #define PFFOR 4 1960 #define PAGEORDER_SIZE (PFBAK+PFFOR) 1961 1962 static int vm_prefault_pageorder[] = { 1963 -PAGE_SIZE, PAGE_SIZE, 1964 -2 * PAGE_SIZE, 2 * PAGE_SIZE, 1965 -3 * PAGE_SIZE, 3 * PAGE_SIZE, 1966 -4 * PAGE_SIZE, 4 * PAGE_SIZE 1967 }; 1968 1969 /* 1970 * Set PG_NOSYNC if the map entry indicates so, but only if the page 1971 * is not already dirty by other means. This will prevent passive 1972 * filesystem syncing as well as 'sync' from writing out the page. 1973 */ 1974 static void 1975 vm_set_nosync(vm_page_t m, vm_map_entry_t entry) 1976 { 1977 if (entry->eflags & MAP_ENTRY_NOSYNC) { 1978 if (m->dirty == 0) 1979 vm_page_flag_set(m, PG_NOSYNC); 1980 } else { 1981 vm_page_flag_clear(m, PG_NOSYNC); 1982 } 1983 } 1984 1985 static void 1986 vm_prefault(pmap_t pmap, vm_offset_t addra, vm_map_entry_t entry, int prot) 1987 { 1988 struct lwp *lp; 1989 vm_page_t m; 1990 vm_offset_t starta; 1991 vm_offset_t addr; 1992 vm_pindex_t index; 1993 vm_pindex_t pindex; 1994 vm_object_t object; 1995 int pprot; 1996 int i; 1997 1998 /* 1999 * We do not currently prefault mappings that use virtual page 2000 * tables. We do not prefault foreign pmaps. 2001 */ 2002 if (entry->maptype == VM_MAPTYPE_VPAGETABLE) 2003 return; 2004 lp = curthread->td_lwp; 2005 if (lp == NULL || (pmap != vmspace_pmap(lp->lwp_vmspace))) 2006 return; 2007 2008 object = entry->object.vm_object; 2009 2010 starta = addra - PFBAK * PAGE_SIZE; 2011 if (starta < entry->start) 2012 starta = entry->start; 2013 else if (starta > addra) 2014 starta = 0; 2015 2016 lwkt_gettoken(&vm_token); 2017 for (i = 0; i < PAGEORDER_SIZE; i++) { 2018 vm_object_t lobject; 2019 int allocated = 0; 2020 2021 addr = addra + vm_prefault_pageorder[i]; 2022 if (addr > addra + (PFFOR * PAGE_SIZE)) 2023 addr = 0; 2024 2025 if (addr < starta || addr >= entry->end) 2026 continue; 2027 2028 if (pmap_prefault_ok(pmap, addr) == 0) 2029 continue; 2030 2031 /* 2032 * Follow the VM object chain to obtain the page to be mapped 2033 * into the pmap. 2034 * 2035 * If we reach the terminal object without finding a page 2036 * and we determine it would be advantageous, then allocate 2037 * a zero-fill page for the base object. The base object 2038 * is guaranteed to be OBJT_DEFAULT for this case. 2039 * 2040 * In order to not have to check the pager via *haspage*() 2041 * we stop if any non-default object is encountered. e.g. 2042 * a vnode or swap object would stop the loop. 2043 */ 2044 index = ((addr - entry->start) + entry->offset) >> PAGE_SHIFT; 2045 lobject = object; 2046 pindex = index; 2047 pprot = prot; 2048 2049 while ((m = vm_page_lookup(lobject, pindex)) == NULL) { 2050 if (lobject->type != OBJT_DEFAULT) 2051 break; 2052 if (lobject->backing_object == NULL) { 2053 if (vm_fast_fault == 0) 2054 break; 2055 if (vm_prefault_pageorder[i] < 0 || 2056 (prot & VM_PROT_WRITE) == 0 || 2057 vm_page_count_min(0)) { 2058 break; 2059 } 2060 /* note: allocate from base object */ 2061 m = vm_page_alloc(object, index, 2062 VM_ALLOC_NORMAL | VM_ALLOC_ZERO); 2063 2064 if ((m->flags & PG_ZERO) == 0) { 2065 vm_page_zero_fill(m); 2066 } else { 2067 #ifdef PMAP_DEBUG 2068 pmap_page_assertzero(VM_PAGE_TO_PHYS(m)); 2069 #endif 2070 vm_page_flag_clear(m, PG_ZERO); 2071 mycpu->gd_cnt.v_ozfod++; 2072 } 2073 mycpu->gd_cnt.v_zfod++; 2074 m->valid = VM_PAGE_BITS_ALL; 2075 allocated = 1; 2076 pprot = prot; 2077 /* lobject = object .. not needed */ 2078 break; 2079 } 2080 if (lobject->backing_object_offset & PAGE_MASK) 2081 break; 2082 pindex += lobject->backing_object_offset >> PAGE_SHIFT; 2083 lobject = lobject->backing_object; 2084 pprot &= ~VM_PROT_WRITE; 2085 } 2086 /* 2087 * NOTE: lobject now invalid (if we did a zero-fill we didn't 2088 * bother assigning lobject = object). 2089 * 2090 * Give-up if the page is not available. 2091 */ 2092 if (m == NULL) 2093 break; 2094 2095 /* 2096 * Do not conditionalize on PG_RAM. If pages are present in 2097 * the VM system we assume optimal caching. If caching is 2098 * not optimal the I/O gravy train will be restarted when we 2099 * hit an unavailable page. We do not want to try to restart 2100 * the gravy train now because we really don't know how much 2101 * of the object has been cached. The cost for restarting 2102 * the gravy train should be low (since accesses will likely 2103 * be I/O bound anyway). 2104 * 2105 * The object must be marked dirty if we are mapping a 2106 * writable page. 2107 */ 2108 if (pprot & VM_PROT_WRITE) 2109 vm_object_set_writeable_dirty(m->object); 2110 2111 /* 2112 * Enter the page into the pmap if appropriate. If we had 2113 * allocated the page we have to place it on a queue. If not 2114 * we just have to make sure it isn't on the cache queue 2115 * (pages on the cache queue are not allowed to be mapped). 2116 */ 2117 if (allocated) { 2118 if (pprot & VM_PROT_WRITE) 2119 vm_set_nosync(m, entry); 2120 pmap_enter(pmap, addr, m, pprot, 0); 2121 vm_page_deactivate(m); 2122 vm_page_wakeup(m); 2123 } else if (((m->valid & VM_PAGE_BITS_ALL) == VM_PAGE_BITS_ALL) && 2124 (m->busy == 0) && 2125 (m->flags & (PG_BUSY | PG_FICTITIOUS)) == 0) { 2126 2127 vm_page_busy(m); 2128 if ((m->queue - m->pc) == PQ_CACHE) { 2129 vm_page_deactivate(m); 2130 } 2131 if (pprot & VM_PROT_WRITE) 2132 vm_set_nosync(m, entry); 2133 pmap_enter(pmap, addr, m, pprot, 0); 2134 vm_page_wakeup(m); 2135 } 2136 } 2137 lwkt_reltoken(&vm_token); 2138 } 2139