1 /* $NetBSD: uvm_fault.c,v 1.234 2023/08/13 23:06:07 chs Exp $ */ 2 3 /* 4 * Copyright (c) 1997 Charles D. Cranor and Washington University. 5 * All rights reserved. 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 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 * from: Id: uvm_fault.c,v 1.1.2.23 1998/02/06 05:29:05 chs Exp 28 */ 29 30 /* 31 * uvm_fault.c: fault handler 32 */ 33 34 #include <sys/cdefs.h> 35 __KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.234 2023/08/13 23:06:07 chs Exp $"); 36 37 #include "opt_uvmhist.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/atomic.h> 42 #include <sys/kernel.h> 43 #include <sys/mman.h> 44 45 #include <uvm/uvm.h> 46 #include <uvm/uvm_pdpolicy.h> 47 #include <uvm/uvm_rndsource.h> 48 49 /* 50 * 51 * a word on page faults: 52 * 53 * types of page faults we handle: 54 * 55 * CASE 1: upper layer faults CASE 2: lower layer faults 56 * 57 * CASE 1A CASE 1B CASE 2A CASE 2B 58 * read/write1 write>1 read/write +-cow_write/zero 59 * | | | | 60 * +--|--+ +--|--+ +-----+ + | + | +-----+ 61 * amap | V | | ---------> new | | | | ^ | 62 * +-----+ +-----+ +-----+ + | + | +--|--+ 63 * | | | 64 * +-----+ +-----+ +--|--+ | +--|--+ 65 * uobj | d/c | | d/c | | V | +----+ | 66 * +-----+ +-----+ +-----+ +-----+ 67 * 68 * d/c = don't care 69 * 70 * case [0]: layerless fault 71 * no amap or uobj is present. this is an error. 72 * 73 * case [1]: upper layer fault [anon active] 74 * 1A: [read] or [write with anon->an_ref == 1] 75 * I/O takes place in upper level anon and uobj is not touched. 76 * 1B: [write with anon->an_ref > 1] 77 * new anon is alloc'd and data is copied off ["COW"] 78 * 79 * case [2]: lower layer fault [uobj] 80 * 2A: [read on non-NULL uobj] or [write to non-copy_on_write area] 81 * I/O takes place directly in object. 82 * 2B: [write to copy_on_write] or [read on NULL uobj] 83 * data is "promoted" from uobj to a new anon. 84 * if uobj is null, then we zero fill. 85 * 86 * we follow the standard UVM locking protocol ordering: 87 * 88 * MAPS => AMAP => UOBJ => ANON => PAGE QUEUES (PQ) 89 * we hold a PG_BUSY page if we unlock for I/O 90 * 91 * 92 * the code is structured as follows: 93 * 94 * - init the "IN" params in the ufi structure 95 * ReFault: (ERESTART returned to the loop in uvm_fault_internal) 96 * - do lookups [locks maps], check protection, handle needs_copy 97 * - check for case 0 fault (error) 98 * - establish "range" of fault 99 * - if we have an amap lock it and extract the anons 100 * - if sequential advice deactivate pages behind us 101 * - at the same time check pmap for unmapped areas and anon for pages 102 * that we could map in (and do map it if found) 103 * - check object for resident pages that we could map in 104 * - if (case 2) goto Case2 105 * - >>> handle case 1 106 * - ensure source anon is resident in RAM 107 * - if case 1B alloc new anon and copy from source 108 * - map the correct page in 109 * Case2: 110 * - >>> handle case 2 111 * - ensure source page is resident (if uobj) 112 * - if case 2B alloc new anon and copy from source (could be zero 113 * fill if uobj == NULL) 114 * - map the correct page in 115 * - done! 116 * 117 * note on paging: 118 * if we have to do I/O we place a PG_BUSY page in the correct object, 119 * unlock everything, and do the I/O. when I/O is done we must reverify 120 * the state of the world before assuming that our data structures are 121 * valid. [because mappings could change while the map is unlocked] 122 * 123 * alternative 1: unbusy the page in question and restart the page fault 124 * from the top (ReFault). this is easy but does not take advantage 125 * of the information that we already have from our previous lookup, 126 * although it is possible that the "hints" in the vm_map will help here. 127 * 128 * alternative 2: the system already keeps track of a "version" number of 129 * a map. [i.e. every time you write-lock a map (e.g. to change a 130 * mapping) you bump the version number up by one...] so, we can save 131 * the version number of the map before we release the lock and start I/O. 132 * then when I/O is done we can relock and check the version numbers 133 * to see if anything changed. this might save us some over 1 because 134 * we don't have to unbusy the page and may be less compares(?). 135 * 136 * alternative 3: put in backpointers or a way to "hold" part of a map 137 * in place while I/O is in progress. this could be complex to 138 * implement (especially with structures like amap that can be referenced 139 * by multiple map entries, and figuring out what should wait could be 140 * complex as well...). 141 * 142 * we use alternative 2. given that we are multi-threaded now we may want 143 * to reconsider the choice. 144 */ 145 146 /* 147 * local data structures 148 */ 149 150 struct uvm_advice { 151 int advice; 152 int nback; 153 int nforw; 154 }; 155 156 /* 157 * page range array: 158 * note: index in array must match "advice" value 159 * XXX: borrowed numbers from freebsd. do they work well for us? 160 */ 161 162 static const struct uvm_advice uvmadvice[] = { 163 { UVM_ADV_NORMAL, 3, 4 }, 164 { UVM_ADV_RANDOM, 0, 0 }, 165 { UVM_ADV_SEQUENTIAL, 8, 7}, 166 }; 167 168 #define UVM_MAXRANGE 16 /* must be MAX() of nback+nforw+1 */ 169 170 /* 171 * private prototypes 172 */ 173 174 /* 175 * inline functions 176 */ 177 178 /* 179 * uvmfault_anonflush: try and deactivate pages in specified anons 180 * 181 * => does not have to deactivate page if it is busy 182 */ 183 184 static inline void 185 uvmfault_anonflush(struct vm_anon **anons, int n) 186 { 187 int lcv; 188 struct vm_page *pg; 189 190 for (lcv = 0; lcv < n; lcv++) { 191 if (anons[lcv] == NULL) 192 continue; 193 KASSERT(rw_lock_held(anons[lcv]->an_lock)); 194 pg = anons[lcv]->an_page; 195 if (pg && (pg->flags & PG_BUSY) == 0) { 196 uvm_pagelock(pg); 197 uvm_pagedeactivate(pg); 198 uvm_pageunlock(pg); 199 } 200 } 201 } 202 203 /* 204 * normal functions 205 */ 206 207 /* 208 * uvmfault_amapcopy: clear "needs_copy" in a map. 209 * 210 * => called with VM data structures unlocked (usually, see below) 211 * => we get a write lock on the maps and clear needs_copy for a VA 212 * => if we are out of RAM we sleep (waiting for more) 213 */ 214 215 static void 216 uvmfault_amapcopy(struct uvm_faultinfo *ufi) 217 { 218 for (;;) { 219 220 /* 221 * no mapping? give up. 222 */ 223 224 if (uvmfault_lookup(ufi, true) == false) 225 return; 226 227 /* 228 * copy if needed. 229 */ 230 231 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) 232 amap_copy(ufi->map, ufi->entry, AMAP_COPY_NOWAIT, 233 ufi->orig_rvaddr, ufi->orig_rvaddr + 1); 234 235 /* 236 * didn't work? must be out of RAM. unlock and sleep. 237 */ 238 239 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 240 uvmfault_unlockmaps(ufi, true); 241 uvm_wait("fltamapcopy"); 242 continue; 243 } 244 245 /* 246 * got it! unlock and return. 247 */ 248 249 uvmfault_unlockmaps(ufi, true); 250 return; 251 } 252 /*NOTREACHED*/ 253 } 254 255 /* 256 * uvmfault_anonget: get data in an anon into a non-busy, non-released 257 * page in that anon. 258 * 259 * => Map, amap and thus anon should be locked by caller. 260 * => If we fail, we unlock everything and error is returned. 261 * => If we are successful, return with everything still locked. 262 * => We do not move the page on the queues [gets moved later]. If we 263 * allocate a new page [we_own], it gets put on the queues. Either way, 264 * the result is that the page is on the queues at return time 265 * => For pages which are on loan from a uvm_object (and thus are not owned 266 * by the anon): if successful, return with the owning object locked. 267 * The caller must unlock this object when it unlocks everything else. 268 */ 269 270 int 271 uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap, 272 struct vm_anon *anon) 273 { 274 struct vm_page *pg; 275 krw_t lock_type; 276 int error; 277 278 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 279 KASSERT(rw_lock_held(anon->an_lock)); 280 KASSERT(anon->an_lock == amap->am_lock); 281 282 /* Increment the counters.*/ 283 cpu_count(CPU_COUNT_FLTANGET, 1); 284 if (anon->an_page) { 285 curlwp->l_ru.ru_minflt++; 286 } else { 287 curlwp->l_ru.ru_majflt++; 288 } 289 error = 0; 290 291 /* 292 * Loop until we get the anon data, or fail. 293 */ 294 295 for (;;) { 296 bool we_own, locked; 297 /* 298 * Note: 'we_own' will become true if we set PG_BUSY on a page. 299 */ 300 we_own = false; 301 pg = anon->an_page; 302 303 /* 304 * If there is a resident page and it is loaned, then anon 305 * may not own it. Call out to uvm_anon_lockloanpg() to 306 * identify and lock the real owner of the page. 307 */ 308 309 if (pg && pg->loan_count) 310 pg = uvm_anon_lockloanpg(anon); 311 312 /* 313 * Is page resident? Make sure it is not busy/released. 314 */ 315 316 lock_type = rw_lock_op(anon->an_lock); 317 if (pg) { 318 319 /* 320 * at this point, if the page has a uobject [meaning 321 * we have it on loan], then that uobject is locked 322 * by us! if the page is busy, we drop all the 323 * locks (including uobject) and try again. 324 */ 325 326 if ((pg->flags & PG_BUSY) == 0) { 327 UVMHIST_LOG(maphist, "<- OK",0,0,0,0); 328 return 0; 329 } 330 cpu_count(CPU_COUNT_FLTPGWAIT, 1); 331 332 /* 333 * The last unlock must be an atomic unlock and wait 334 * on the owner of page. 335 */ 336 337 if (pg->uobject) { 338 /* Owner of page is UVM object. */ 339 uvmfault_unlockall(ufi, amap, NULL); 340 UVMHIST_LOG(maphist, " unlock+wait on uobj",0, 341 0,0,0); 342 uvm_pagewait(pg, pg->uobject->vmobjlock, "anonget1"); 343 } else { 344 /* Owner of page is anon. */ 345 uvmfault_unlockall(ufi, NULL, NULL); 346 UVMHIST_LOG(maphist, " unlock+wait on anon",0, 347 0,0,0); 348 uvm_pagewait(pg, anon->an_lock, "anonget2"); 349 } 350 } else { 351 #if defined(VMSWAP) 352 /* 353 * No page, therefore allocate one. A write lock is 354 * required for this. If the caller didn't supply 355 * one, fail now and have them retry. 356 */ 357 358 if (lock_type == RW_READER) { 359 return ENOLCK; 360 } 361 pg = uvm_pagealloc(NULL, 362 ufi != NULL ? ufi->orig_rvaddr : 0, 363 anon, ufi != NULL ? UVM_FLAG_COLORMATCH : 0); 364 if (pg == NULL) { 365 /* Out of memory. Wait a little. */ 366 uvmfault_unlockall(ufi, amap, NULL); 367 cpu_count(CPU_COUNT_FLTNORAM, 1); 368 UVMHIST_LOG(maphist, " noram -- UVM_WAIT",0, 369 0,0,0); 370 if (!uvm_reclaimable()) { 371 return ENOMEM; 372 } 373 uvm_wait("flt_noram1"); 374 } else { 375 /* PG_BUSY bit is set. */ 376 we_own = true; 377 uvmfault_unlockall(ufi, amap, NULL); 378 379 /* 380 * Pass a PG_BUSY+PG_FAKE clean page into 381 * the uvm_swap_get() function with all data 382 * structures unlocked. Note that it is OK 383 * to read an_swslot here, because we hold 384 * PG_BUSY on the page. 385 */ 386 cpu_count(CPU_COUNT_PAGEINS, 1); 387 error = uvm_swap_get(pg, anon->an_swslot, 388 PGO_SYNCIO); 389 390 /* 391 * We clean up after the I/O below in the 392 * 'we_own' case. 393 */ 394 } 395 #else 396 panic("%s: no page", __func__); 397 #endif /* defined(VMSWAP) */ 398 } 399 400 /* 401 * Re-lock the map and anon. 402 */ 403 404 locked = uvmfault_relock(ufi); 405 if (locked || we_own) { 406 rw_enter(anon->an_lock, lock_type); 407 } 408 409 /* 410 * If we own the page (i.e. we set PG_BUSY), then we need 411 * to clean up after the I/O. There are three cases to 412 * consider: 413 * 414 * 1) Page was released during I/O: free anon and ReFault. 415 * 2) I/O not OK. Free the page and cause the fault to fail. 416 * 3) I/O OK! Activate the page and sync with the non-we_own 417 * case (i.e. drop anon lock if not locked). 418 */ 419 420 if (we_own) { 421 KASSERT(lock_type == RW_WRITER); 422 #if defined(VMSWAP) 423 if (error) { 424 425 /* 426 * Remove the swap slot from the anon and 427 * mark the anon as having no real slot. 428 * Do not free the swap slot, thus preventing 429 * it from being used again. 430 */ 431 432 if (anon->an_swslot > 0) { 433 uvm_swap_markbad(anon->an_swslot, 1); 434 } 435 anon->an_swslot = SWSLOT_BAD; 436 437 if ((pg->flags & PG_RELEASED) != 0) { 438 goto released; 439 } 440 441 /* 442 * Note: page was never !PG_BUSY, so it 443 * cannot be mapped and thus no need to 444 * pmap_page_protect() it. 445 */ 446 447 uvm_pagefree(pg); 448 449 if (locked) { 450 uvmfault_unlockall(ufi, NULL, NULL); 451 } 452 rw_exit(anon->an_lock); 453 UVMHIST_LOG(maphist, "<- ERROR", 0,0,0,0); 454 return error; 455 } 456 457 if ((pg->flags & PG_RELEASED) != 0) { 458 released: 459 KASSERT(anon->an_ref == 0); 460 461 /* 462 * Released while we had unlocked amap. 463 */ 464 465 if (locked) { 466 uvmfault_unlockall(ufi, NULL, NULL); 467 } 468 uvm_anon_release(anon); 469 470 if (error) { 471 UVMHIST_LOG(maphist, 472 "<- ERROR/RELEASED", 0,0,0,0); 473 return error; 474 } 475 476 UVMHIST_LOG(maphist, "<- RELEASED", 0,0,0,0); 477 return ERESTART; 478 } 479 480 /* 481 * We have successfully read the page, activate it. 482 */ 483 484 uvm_pagelock(pg); 485 uvm_pageactivate(pg); 486 uvm_pagewakeup(pg); 487 uvm_pageunlock(pg); 488 pg->flags &= ~(PG_BUSY|PG_FAKE); 489 uvm_pagemarkdirty(pg, UVM_PAGE_STATUS_UNKNOWN); 490 UVM_PAGE_OWN(pg, NULL); 491 #else 492 panic("%s: we_own", __func__); 493 #endif /* defined(VMSWAP) */ 494 } 495 496 /* 497 * We were not able to re-lock the map - restart the fault. 498 */ 499 500 if (!locked) { 501 if (we_own) { 502 rw_exit(anon->an_lock); 503 } 504 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 505 return ERESTART; 506 } 507 508 /* 509 * Verify that no one has touched the amap and moved 510 * the anon on us. 511 */ 512 513 if (ufi != NULL && amap_lookup(&ufi->entry->aref, 514 ufi->orig_rvaddr - ufi->entry->start) != anon) { 515 516 uvmfault_unlockall(ufi, amap, NULL); 517 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 518 return ERESTART; 519 } 520 521 /* 522 * Retry.. 523 */ 524 525 cpu_count(CPU_COUNT_FLTANRETRY, 1); 526 continue; 527 } 528 /*NOTREACHED*/ 529 } 530 531 /* 532 * uvmfault_promote: promote data to a new anon. used for 1B and 2B. 533 * 534 * 1. allocate an anon and a page. 535 * 2. fill its contents. 536 * 3. put it into amap. 537 * 538 * => if we fail (result != 0) we unlock everything. 539 * => on success, return a new locked anon via 'nanon'. 540 * (*nanon)->an_page will be a resident, locked, dirty page. 541 * => it's caller's responsibility to put the promoted nanon->an_page to the 542 * page queue. 543 */ 544 545 static int 546 uvmfault_promote(struct uvm_faultinfo *ufi, 547 struct vm_anon *oanon, 548 struct vm_page *uobjpage, 549 struct vm_anon **nanon, /* OUT: allocated anon */ 550 struct vm_anon **spare) 551 { 552 struct vm_amap *amap = ufi->entry->aref.ar_amap; 553 struct uvm_object *uobj; 554 struct vm_anon *anon; 555 struct vm_page *pg; 556 struct vm_page *opg; 557 int error; 558 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 559 560 if (oanon) { 561 /* anon COW */ 562 opg = oanon->an_page; 563 KASSERT(opg != NULL); 564 KASSERT(opg->uobject == NULL || opg->loan_count > 0); 565 } else if (uobjpage != PGO_DONTCARE) { 566 /* object-backed COW */ 567 opg = uobjpage; 568 KASSERT(rw_lock_held(opg->uobject->vmobjlock)); 569 } else { 570 /* ZFOD */ 571 opg = NULL; 572 } 573 if (opg != NULL) { 574 uobj = opg->uobject; 575 } else { 576 uobj = NULL; 577 } 578 579 KASSERT(amap != NULL); 580 KASSERT(uobjpage != NULL); 581 KASSERT(rw_write_held(amap->am_lock)); 582 KASSERT(oanon == NULL || amap->am_lock == oanon->an_lock); 583 KASSERT(uobj == NULL || rw_lock_held(uobj->vmobjlock)); 584 585 if (*spare != NULL) { 586 anon = *spare; 587 *spare = NULL; 588 } else { 589 anon = uvm_analloc(); 590 } 591 if (anon) { 592 593 /* 594 * The new anon is locked. 595 * 596 * if opg == NULL, we want a zero'd, dirty page, 597 * so have uvm_pagealloc() do that for us. 598 */ 599 600 KASSERT(anon->an_lock == NULL); 601 anon->an_lock = amap->am_lock; 602 pg = uvm_pagealloc(NULL, ufi->orig_rvaddr, anon, 603 UVM_FLAG_COLORMATCH | (opg == NULL ? UVM_PGA_ZERO : 0)); 604 if (pg == NULL) { 605 anon->an_lock = NULL; 606 } 607 } else { 608 pg = NULL; 609 } 610 611 /* 612 * out of memory resources? 613 */ 614 615 if (pg == NULL) { 616 /* save anon for the next try. */ 617 if (anon != NULL) { 618 *spare = anon; 619 } 620 621 /* unlock and fail ... */ 622 uvmfault_unlockall(ufi, amap, uobj); 623 if (!uvm_reclaimable()) { 624 UVMHIST_LOG(maphist, "out of VM", 0,0,0,0); 625 cpu_count(CPU_COUNT_FLTNOANON, 1); 626 error = ENOMEM; 627 goto done; 628 } 629 630 UVMHIST_LOG(maphist, "out of RAM, waiting for more", 0,0,0,0); 631 cpu_count(CPU_COUNT_FLTNORAM, 1); 632 uvm_wait("flt_noram5"); 633 error = ERESTART; 634 goto done; 635 } 636 637 /* 638 * copy the page [pg now dirty] 639 * 640 * Remove the pmap entry now for the old page at this address 641 * so that no thread can modify the new page while any thread 642 * might still see the old page. 643 */ 644 if (opg) { 645 pmap_remove(vm_map_pmap(ufi->orig_map), ufi->orig_rvaddr, 646 ufi->orig_rvaddr + PAGE_SIZE); 647 pmap_update(vm_map_pmap(ufi->orig_map)); 648 uvm_pagecopy(opg, pg); 649 } 650 KASSERT(uvm_pagegetdirty(pg) == UVM_PAGE_STATUS_DIRTY); 651 652 amap_add(&ufi->entry->aref, ufi->orig_rvaddr - ufi->entry->start, anon, 653 oanon != NULL); 654 655 /* 656 * from this point on am_lock won't be dropped until the page is 657 * entered, so it's safe to unbusy the page up front. 658 * 659 * uvm_fault_{upper,lower}_done will activate or enqueue the page. 660 */ 661 662 pg = anon->an_page; 663 pg->flags &= ~(PG_BUSY|PG_FAKE); 664 UVM_PAGE_OWN(pg, NULL); 665 666 *nanon = anon; 667 error = 0; 668 done: 669 return error; 670 } 671 672 /* 673 * Update statistics after fault resolution. 674 * - maxrss 675 */ 676 void 677 uvmfault_update_stats(struct uvm_faultinfo *ufi) 678 { 679 struct vm_map *map; 680 struct vmspace *vm; 681 struct proc *p; 682 vsize_t res; 683 684 map = ufi->orig_map; 685 686 p = curproc; 687 KASSERT(p != NULL); 688 vm = p->p_vmspace; 689 690 if (&vm->vm_map != map) 691 return; 692 693 res = pmap_resident_count(map->pmap); 694 if (vm->vm_rssmax < res) 695 vm->vm_rssmax = res; 696 } 697 698 /* 699 * F A U L T - m a i n e n t r y p o i n t 700 */ 701 702 /* 703 * uvm_fault: page fault handler 704 * 705 * => called from MD code to resolve a page fault 706 * => VM data structures usually should be unlocked. however, it is 707 * possible to call here with the main map locked if the caller 708 * gets a write lock, sets it recursive, and then calls us (c.f. 709 * uvm_map_pageable). this should be avoided because it keeps 710 * the map locked off during I/O. 711 * => MUST NEVER BE CALLED IN INTERRUPT CONTEXT 712 */ 713 714 #define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \ 715 ~VM_PROT_WRITE : VM_PROT_ALL) 716 717 /* fault_flag values passed from uvm_fault_wire to uvm_fault_internal */ 718 #define UVM_FAULT_WIRE (1 << 0) 719 #define UVM_FAULT_MAXPROT (1 << 1) 720 721 struct uvm_faultctx { 722 723 /* 724 * the following members are set up by uvm_fault_check() and 725 * read-only after that. 726 * 727 * note that narrow is used by uvm_fault_check() to change 728 * the behaviour after ERESTART. 729 * 730 * most of them might change after RESTART if the underlying 731 * map entry has been changed behind us. an exception is 732 * wire_paging, which does never change. 733 */ 734 vm_prot_t access_type; 735 vaddr_t startva; 736 int npages; 737 int centeridx; 738 bool narrow; /* work on a single requested page only */ 739 bool wire_mapping; /* request a PMAP_WIRED mapping 740 (UVM_FAULT_WIRE or VM_MAPENT_ISWIRED) */ 741 bool wire_paging; /* request uvm_pagewire 742 (true for UVM_FAULT_WIRE) */ 743 bool cow_now; /* VM_PROT_WRITE is actually requested 744 (ie. should break COW and page loaning) */ 745 746 /* 747 * enter_prot is set up by uvm_fault_check() and clamped 748 * (ie. drop the VM_PROT_WRITE bit) in various places in case 749 * of !cow_now. 750 */ 751 vm_prot_t enter_prot; /* prot at which we want to enter pages in */ 752 753 /* 754 * the following member is for uvmfault_promote() and ERESTART. 755 */ 756 struct vm_anon *anon_spare; 757 758 /* 759 * the following is actually a uvm_fault_lower() internal. 760 * it's here merely for debugging. 761 * (or due to the mechanical separation of the function?) 762 */ 763 bool promote; 764 765 /* 766 * type of lock to acquire on objects in both layers. 767 */ 768 krw_t lower_lock_type; 769 krw_t upper_lock_type; 770 }; 771 772 static inline int uvm_fault_check( 773 struct uvm_faultinfo *, struct uvm_faultctx *, 774 struct vm_anon ***, bool); 775 776 static int uvm_fault_upper( 777 struct uvm_faultinfo *, struct uvm_faultctx *, 778 struct vm_anon **); 779 static inline int uvm_fault_upper_lookup( 780 struct uvm_faultinfo *, const struct uvm_faultctx *, 781 struct vm_anon **, struct vm_page **); 782 static inline void uvm_fault_upper_neighbor( 783 struct uvm_faultinfo *, const struct uvm_faultctx *, 784 vaddr_t, struct vm_page *, bool); 785 static inline int uvm_fault_upper_loan( 786 struct uvm_faultinfo *, struct uvm_faultctx *, 787 struct vm_anon *, struct uvm_object **); 788 static inline int uvm_fault_upper_promote( 789 struct uvm_faultinfo *, struct uvm_faultctx *, 790 struct uvm_object *, struct vm_anon *); 791 static inline int uvm_fault_upper_direct( 792 struct uvm_faultinfo *, struct uvm_faultctx *, 793 struct uvm_object *, struct vm_anon *); 794 static int uvm_fault_upper_enter( 795 struct uvm_faultinfo *, const struct uvm_faultctx *, 796 struct uvm_object *, struct vm_anon *, 797 struct vm_page *, struct vm_anon *); 798 static inline void uvm_fault_upper_done( 799 struct uvm_faultinfo *, const struct uvm_faultctx *, 800 struct vm_anon *, struct vm_page *); 801 802 static int uvm_fault_lower( 803 struct uvm_faultinfo *, struct uvm_faultctx *, 804 struct vm_page **); 805 static inline void uvm_fault_lower_lookup( 806 struct uvm_faultinfo *, const struct uvm_faultctx *, 807 struct vm_page **); 808 static inline void uvm_fault_lower_neighbor( 809 struct uvm_faultinfo *, const struct uvm_faultctx *, 810 vaddr_t, struct vm_page *); 811 static inline int uvm_fault_lower_io( 812 struct uvm_faultinfo *, struct uvm_faultctx *, 813 struct uvm_object **, struct vm_page **); 814 static inline int uvm_fault_lower_direct( 815 struct uvm_faultinfo *, struct uvm_faultctx *, 816 struct uvm_object *, struct vm_page *); 817 static inline int uvm_fault_lower_direct_loan( 818 struct uvm_faultinfo *, struct uvm_faultctx *, 819 struct uvm_object *, struct vm_page **, 820 struct vm_page **); 821 static inline int uvm_fault_lower_promote( 822 struct uvm_faultinfo *, struct uvm_faultctx *, 823 struct uvm_object *, struct vm_page *); 824 static int uvm_fault_lower_enter( 825 struct uvm_faultinfo *, const struct uvm_faultctx *, 826 struct uvm_object *, 827 struct vm_anon *, struct vm_page *); 828 static inline void uvm_fault_lower_done( 829 struct uvm_faultinfo *, const struct uvm_faultctx *, 830 struct uvm_object *, struct vm_page *); 831 832 int 833 uvm_fault_internal(struct vm_map *orig_map, vaddr_t vaddr, 834 vm_prot_t access_type, int fault_flag) 835 { 836 struct uvm_faultinfo ufi; 837 struct uvm_faultctx flt = { 838 .access_type = access_type, 839 840 /* don't look for neighborhood * pages on "wire" fault */ 841 .narrow = (fault_flag & UVM_FAULT_WIRE) != 0, 842 843 /* "wire" fault causes wiring of both mapping and paging */ 844 .wire_mapping = (fault_flag & UVM_FAULT_WIRE) != 0, 845 .wire_paging = (fault_flag & UVM_FAULT_WIRE) != 0, 846 847 /* 848 * default lock type to acquire on upper & lower layer 849 * objects: reader. this can be upgraded at any point 850 * during the fault from read -> write and uvm_faultctx 851 * changed to match, but is never downgraded write -> read. 852 */ 853 #ifdef __HAVE_UNLOCKED_PMAP /* XXX temporary */ 854 .upper_lock_type = RW_WRITER, 855 .lower_lock_type = RW_WRITER, 856 #else 857 .upper_lock_type = RW_READER, 858 .lower_lock_type = RW_READER, 859 #endif 860 }; 861 const bool maxprot = (fault_flag & UVM_FAULT_MAXPROT) != 0; 862 struct vm_anon *anons_store[UVM_MAXRANGE], **anons; 863 struct vm_page *pages_store[UVM_MAXRANGE], **pages; 864 int error; 865 866 UVMHIST_FUNC(__func__); 867 UVMHIST_CALLARGS(maphist, "(map=%#jx, vaddr=%#jx, at=%jd, ff=%jd)", 868 (uintptr_t)orig_map, vaddr, access_type, fault_flag); 869 870 /* Don't count anything until user interaction is possible */ 871 kpreempt_disable(); 872 if (__predict_true(start_init_exec)) { 873 struct cpu_info *ci = curcpu(); 874 CPU_COUNT(CPU_COUNT_NFAULT, 1); 875 /* Don't flood RNG subsystem with samples. */ 876 if (++(ci->ci_faultrng) == 503) { 877 ci->ci_faultrng = 0; 878 rnd_add_uint32(&uvm_fault_rndsource, 879 sizeof(vaddr_t) == sizeof(uint32_t) ? 880 (uint32_t)vaddr : sizeof(vaddr_t) == 881 sizeof(uint64_t) ? 882 (uint32_t)vaddr : 883 (uint32_t)ci->ci_counts[CPU_COUNT_NFAULT]); 884 } 885 } 886 kpreempt_enable(); 887 888 /* 889 * init the IN parameters in the ufi 890 */ 891 892 ufi.orig_map = orig_map; 893 ufi.orig_rvaddr = trunc_page(vaddr); 894 ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */ 895 896 error = ERESTART; 897 while (error == ERESTART) { /* ReFault: */ 898 anons = anons_store; 899 pages = pages_store; 900 901 error = uvm_fault_check(&ufi, &flt, &anons, maxprot); 902 if (error != 0) 903 continue; 904 905 error = uvm_fault_upper_lookup(&ufi, &flt, anons, pages); 906 if (error != 0) 907 continue; 908 909 if (pages[flt.centeridx] == PGO_DONTCARE) 910 error = uvm_fault_upper(&ufi, &flt, anons); 911 else { 912 struct uvm_object * const uobj = 913 ufi.entry->object.uvm_obj; 914 915 if (uobj && uobj->pgops->pgo_fault != NULL) { 916 /* 917 * invoke "special" fault routine. 918 */ 919 rw_enter(uobj->vmobjlock, RW_WRITER); 920 /* locked: maps(read), amap(if there), uobj */ 921 error = uobj->pgops->pgo_fault(&ufi, 922 flt.startva, pages, flt.npages, 923 flt.centeridx, flt.access_type, 924 PGO_LOCKED|PGO_SYNCIO); 925 926 /* 927 * locked: nothing, pgo_fault has unlocked 928 * everything 929 */ 930 931 /* 932 * object fault routine responsible for 933 * pmap_update(). 934 */ 935 936 /* 937 * Wake up the pagedaemon if the fault method 938 * failed for lack of memory but some can be 939 * reclaimed. 940 */ 941 if (error == ENOMEM && uvm_reclaimable()) { 942 uvm_wait("pgo_fault"); 943 error = ERESTART; 944 } 945 } else { 946 error = uvm_fault_lower(&ufi, &flt, pages); 947 } 948 } 949 } 950 951 if (flt.anon_spare != NULL) { 952 flt.anon_spare->an_ref--; 953 KASSERT(flt.anon_spare->an_ref == 0); 954 KASSERT(flt.anon_spare->an_lock == NULL); 955 uvm_anfree(flt.anon_spare); 956 } 957 return error; 958 } 959 960 /* 961 * uvm_fault_check: check prot, handle needs-copy, etc. 962 * 963 * 1. lookup entry. 964 * 2. check protection. 965 * 3. adjust fault condition (mainly for simulated fault). 966 * 4. handle needs-copy (lazy amap copy). 967 * 5. establish range of interest for neighbor fault (aka pre-fault). 968 * 6. look up anons (if amap exists). 969 * 7. flush pages (if MADV_SEQUENTIAL) 970 * 971 * => called with nothing locked. 972 * => if we fail (result != 0) we unlock everything. 973 * => initialize/adjust many members of flt. 974 */ 975 976 static int 977 uvm_fault_check( 978 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 979 struct vm_anon ***ranons, bool maxprot) 980 { 981 struct vm_amap *amap; 982 struct uvm_object *uobj; 983 vm_prot_t check_prot; 984 int nback, nforw; 985 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 986 987 /* 988 * lookup and lock the maps 989 */ 990 991 if (uvmfault_lookup(ufi, false) == false) { 992 UVMHIST_LOG(maphist, "<- no mapping @ %#jx", ufi->orig_rvaddr, 993 0,0,0); 994 return EFAULT; 995 } 996 /* locked: maps(read) */ 997 998 #ifdef DIAGNOSTIC 999 if ((ufi->map->flags & VM_MAP_PAGEABLE) == 0) { 1000 printf("Page fault on non-pageable map:\n"); 1001 printf("ufi->map = %p\n", ufi->map); 1002 printf("ufi->orig_map = %p\n", ufi->orig_map); 1003 printf("ufi->orig_rvaddr = %#lx\n", (u_long) ufi->orig_rvaddr); 1004 panic("uvm_fault: (ufi->map->flags & VM_MAP_PAGEABLE) == 0"); 1005 } 1006 #endif 1007 1008 /* 1009 * check protection 1010 */ 1011 1012 check_prot = maxprot ? 1013 ufi->entry->max_protection : ufi->entry->protection; 1014 if ((check_prot & flt->access_type) != flt->access_type) { 1015 UVMHIST_LOG(maphist, 1016 "<- protection failure (prot=%#jx, access=%#jx)", 1017 ufi->entry->protection, flt->access_type, 0, 0); 1018 uvmfault_unlockmaps(ufi, false); 1019 return EFAULT; 1020 } 1021 1022 /* 1023 * "enter_prot" is the protection we want to enter the page in at. 1024 * for certain pages (e.g. copy-on-write pages) this protection can 1025 * be more strict than ufi->entry->protection. "wired" means either 1026 * the entry is wired or we are fault-wiring the pg. 1027 */ 1028 1029 flt->enter_prot = ufi->entry->protection; 1030 if (VM_MAPENT_ISWIRED(ufi->entry)) { 1031 flt->wire_mapping = true; 1032 flt->wire_paging = true; 1033 flt->narrow = true; 1034 } 1035 1036 if (flt->wire_mapping) { 1037 flt->access_type = flt->enter_prot; /* full access for wired */ 1038 flt->cow_now = (check_prot & VM_PROT_WRITE) != 0; 1039 } else { 1040 flt->cow_now = (flt->access_type & VM_PROT_WRITE) != 0; 1041 } 1042 1043 if (flt->wire_paging) { 1044 /* wiring pages requires a write lock. */ 1045 flt->upper_lock_type = RW_WRITER; 1046 flt->lower_lock_type = RW_WRITER; 1047 } 1048 1049 flt->promote = false; 1050 1051 /* 1052 * handle "needs_copy" case. if we need to copy the amap we will 1053 * have to drop our readlock and relock it with a write lock. (we 1054 * need a write lock to change anything in a map entry [e.g. 1055 * needs_copy]). 1056 */ 1057 1058 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 1059 if (flt->cow_now || (ufi->entry->object.uvm_obj == NULL)) { 1060 KASSERT(!maxprot); 1061 /* need to clear */ 1062 UVMHIST_LOG(maphist, 1063 " need to clear needs_copy and refault",0,0,0,0); 1064 uvmfault_unlockmaps(ufi, false); 1065 uvmfault_amapcopy(ufi); 1066 cpu_count(CPU_COUNT_FLTAMCOPY, 1); 1067 return ERESTART; 1068 1069 } else { 1070 1071 /* 1072 * ensure that we pmap_enter page R/O since 1073 * needs_copy is still true 1074 */ 1075 1076 flt->enter_prot &= ~VM_PROT_WRITE; 1077 } 1078 } 1079 1080 /* 1081 * identify the players 1082 */ 1083 1084 amap = ufi->entry->aref.ar_amap; /* upper layer */ 1085 uobj = ufi->entry->object.uvm_obj; /* lower layer */ 1086 1087 /* 1088 * check for a case 0 fault. if nothing backing the entry then 1089 * error now. 1090 */ 1091 1092 if (amap == NULL && uobj == NULL) { 1093 uvmfault_unlockmaps(ufi, false); 1094 UVMHIST_LOG(maphist,"<- no backing store, no overlay",0,0,0,0); 1095 return EFAULT; 1096 } 1097 1098 /* 1099 * for a case 2B fault waste no time on adjacent pages because 1100 * they are likely already entered. 1101 */ 1102 1103 if (uobj != NULL && amap != NULL && 1104 (flt->access_type & VM_PROT_WRITE) != 0) { 1105 /* wide fault (!narrow) */ 1106 flt->narrow = true; 1107 } 1108 1109 /* 1110 * establish range of interest based on advice from mapper 1111 * and then clip to fit map entry. note that we only want 1112 * to do this the first time through the fault. if we 1113 * ReFault we will disable this by setting "narrow" to true. 1114 */ 1115 1116 if (flt->narrow == false) { 1117 1118 /* wide fault (!narrow) */ 1119 KASSERT(uvmadvice[ufi->entry->advice].advice == 1120 ufi->entry->advice); 1121 nback = MIN(uvmadvice[ufi->entry->advice].nback, 1122 (ufi->orig_rvaddr - ufi->entry->start) >> PAGE_SHIFT); 1123 flt->startva = ufi->orig_rvaddr - (nback << PAGE_SHIFT); 1124 /* 1125 * note: "-1" because we don't want to count the 1126 * faulting page as forw 1127 */ 1128 nforw = MIN(uvmadvice[ufi->entry->advice].nforw, 1129 ((ufi->entry->end - ufi->orig_rvaddr) >> 1130 PAGE_SHIFT) - 1); 1131 flt->npages = nback + nforw + 1; 1132 flt->centeridx = nback; 1133 1134 flt->narrow = true; /* ensure only once per-fault */ 1135 1136 } else { 1137 1138 /* narrow fault! */ 1139 nback = nforw = 0; 1140 flt->startva = ufi->orig_rvaddr; 1141 flt->npages = 1; 1142 flt->centeridx = 0; 1143 1144 } 1145 /* offset from entry's start to pgs' start */ 1146 const voff_t eoff = flt->startva - ufi->entry->start; 1147 1148 /* locked: maps(read) */ 1149 UVMHIST_LOG(maphist, " narrow=%jd, back=%jd, forw=%jd, startva=%#jx", 1150 flt->narrow, nback, nforw, flt->startva); 1151 UVMHIST_LOG(maphist, " entry=%#jx, amap=%#jx, obj=%#jx", 1152 (uintptr_t)ufi->entry, (uintptr_t)amap, (uintptr_t)uobj, 0); 1153 1154 /* 1155 * guess at the most suitable lock types to acquire. 1156 * if we've got an amap then lock it and extract current anons. 1157 */ 1158 1159 if (amap) { 1160 if ((amap_flags(amap) & AMAP_SHARED) == 0) { 1161 /* 1162 * the amap isn't shared. get a writer lock to 1163 * avoid the cost of upgrading the lock later if 1164 * needed. 1165 * 1166 * XXX nice for PostgreSQL, but consider threads. 1167 */ 1168 flt->upper_lock_type = RW_WRITER; 1169 } else if ((flt->access_type & VM_PROT_WRITE) != 0) { 1170 /* 1171 * assume we're about to COW. 1172 */ 1173 flt->upper_lock_type = RW_WRITER; 1174 } 1175 amap_lock(amap, flt->upper_lock_type); 1176 amap_lookups(&ufi->entry->aref, eoff, *ranons, flt->npages); 1177 } else { 1178 if ((flt->access_type & VM_PROT_WRITE) != 0) { 1179 /* 1180 * we are about to dirty the object and that 1181 * requires a write lock. 1182 */ 1183 flt->lower_lock_type = RW_WRITER; 1184 } 1185 *ranons = NULL; /* to be safe */ 1186 } 1187 1188 /* locked: maps(read), amap(if there) */ 1189 KASSERT(amap == NULL || 1190 rw_lock_op(amap->am_lock) == flt->upper_lock_type); 1191 1192 /* 1193 * for MADV_SEQUENTIAL mappings we want to deactivate the back pages 1194 * now and then forget about them (for the rest of the fault). 1195 */ 1196 1197 if (ufi->entry->advice == MADV_SEQUENTIAL && nback != 0) { 1198 1199 UVMHIST_LOG(maphist, " MADV_SEQUENTIAL: flushing backpages", 1200 0,0,0,0); 1201 /* flush back-page anons? */ 1202 if (amap) 1203 uvmfault_anonflush(*ranons, nback); 1204 1205 /* 1206 * flush object? change lock type to RW_WRITER, to avoid 1207 * excessive competition between read/write locks if many 1208 * threads doing "sequential access". 1209 */ 1210 if (uobj) { 1211 voff_t uoff; 1212 1213 flt->lower_lock_type = RW_WRITER; 1214 uoff = ufi->entry->offset + eoff; 1215 rw_enter(uobj->vmobjlock, RW_WRITER); 1216 (void) (uobj->pgops->pgo_put)(uobj, uoff, uoff + 1217 (nback << PAGE_SHIFT), PGO_DEACTIVATE); 1218 } 1219 1220 /* now forget about the backpages */ 1221 if (amap) 1222 *ranons += nback; 1223 flt->startva += (nback << PAGE_SHIFT); 1224 flt->npages -= nback; 1225 flt->centeridx = 0; 1226 } 1227 /* 1228 * => startva is fixed 1229 * => npages is fixed 1230 */ 1231 KASSERT(flt->startva <= ufi->orig_rvaddr); 1232 KASSERT(ufi->orig_rvaddr + ufi->orig_size <= 1233 flt->startva + (flt->npages << PAGE_SHIFT)); 1234 return 0; 1235 } 1236 1237 /* 1238 * uvm_fault_upper_upgrade: upgrade upper lock, reader -> writer 1239 */ 1240 1241 static inline int 1242 uvm_fault_upper_upgrade(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1243 struct vm_amap *amap, struct uvm_object *uobj) 1244 { 1245 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1246 1247 KASSERT(amap != NULL); 1248 KASSERT(flt->upper_lock_type == rw_lock_op(amap->am_lock)); 1249 1250 /* 1251 * fast path. 1252 */ 1253 1254 if (__predict_true(flt->upper_lock_type == RW_WRITER)) { 1255 return 0; 1256 } 1257 1258 /* 1259 * otherwise try for the upgrade. if we don't get it, unlock 1260 * everything, restart the fault and next time around get a writer 1261 * lock. 1262 */ 1263 1264 flt->upper_lock_type = RW_WRITER; 1265 if (__predict_false(!rw_tryupgrade(amap->am_lock))) { 1266 uvmfault_unlockall(ufi, amap, uobj); 1267 cpu_count(CPU_COUNT_FLTNOUP, 1); 1268 UVMHIST_LOG(maphist, " !upgrade upper", 0, 0,0,0); 1269 return ERESTART; 1270 } 1271 cpu_count(CPU_COUNT_FLTUP, 1); 1272 KASSERT(flt->upper_lock_type == rw_lock_op(amap->am_lock)); 1273 return 0; 1274 } 1275 1276 /* 1277 * uvm_fault_upper_lookup: look up existing h/w mapping and amap. 1278 * 1279 * iterate range of interest: 1280 * 1. check if h/w mapping exists. if yes, we don't care 1281 * 2. check if anon exists. if not, page is lower. 1282 * 3. if anon exists, enter h/w mapping for neighbors. 1283 * 1284 * => called with amap locked (if exists). 1285 */ 1286 1287 static int 1288 uvm_fault_upper_lookup( 1289 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1290 struct vm_anon **anons, struct vm_page **pages) 1291 { 1292 struct vm_amap *amap = ufi->entry->aref.ar_amap; 1293 int lcv; 1294 vaddr_t currva; 1295 bool shadowed __unused; 1296 bool entered; 1297 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1298 1299 /* locked: maps(read), amap(if there) */ 1300 KASSERT(amap == NULL || 1301 rw_lock_op(amap->am_lock) == flt->upper_lock_type); 1302 1303 /* 1304 * map in the backpages and frontpages we found in the amap in hopes 1305 * of preventing future faults. we also init the pages[] array as 1306 * we go. 1307 */ 1308 1309 currva = flt->startva; 1310 shadowed = false; 1311 entered = false; 1312 for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { 1313 /* 1314 * unmapped or center page. check if any anon at this level. 1315 */ 1316 if (amap == NULL || anons[lcv] == NULL) { 1317 pages[lcv] = NULL; 1318 continue; 1319 } 1320 1321 /* 1322 * check for present page and map if possible. 1323 */ 1324 1325 pages[lcv] = PGO_DONTCARE; 1326 if (lcv == flt->centeridx) { /* save center for later! */ 1327 shadowed = true; 1328 continue; 1329 } 1330 1331 struct vm_anon *anon = anons[lcv]; 1332 struct vm_page *pg = anon->an_page; 1333 1334 KASSERT(anon->an_lock == amap->am_lock); 1335 1336 /* 1337 * ignore loaned and busy pages. 1338 * don't play with VAs that are already mapped. 1339 */ 1340 1341 if (pg && pg->loan_count == 0 && (pg->flags & PG_BUSY) == 0 && 1342 !pmap_extract(ufi->orig_map->pmap, currva, NULL)) { 1343 uvm_fault_upper_neighbor(ufi, flt, currva, 1344 pg, anon->an_ref > 1); 1345 entered = true; 1346 } 1347 } 1348 if (entered) { 1349 pmap_update(ufi->orig_map->pmap); 1350 } 1351 1352 /* locked: maps(read), amap(if there) */ 1353 KASSERT(amap == NULL || 1354 rw_lock_op(amap->am_lock) == flt->upper_lock_type); 1355 /* (shadowed == true) if there is an anon at the faulting address */ 1356 UVMHIST_LOG(maphist, " shadowed=%jd, will_get=%jd", shadowed, 1357 (ufi->entry->object.uvm_obj && shadowed != false),0,0); 1358 1359 return 0; 1360 } 1361 1362 /* 1363 * uvm_fault_upper_neighbor: enter single upper neighbor page. 1364 * 1365 * => called with amap and anon locked. 1366 */ 1367 1368 static void 1369 uvm_fault_upper_neighbor( 1370 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1371 vaddr_t currva, struct vm_page *pg, bool readonly) 1372 { 1373 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1374 1375 /* locked: amap, anon */ 1376 1377 KASSERT(pg->uobject == NULL); 1378 KASSERT(pg->uanon != NULL); 1379 KASSERT(rw_lock_op(pg->uanon->an_lock) == flt->upper_lock_type); 1380 KASSERT(uvm_pagegetdirty(pg) != UVM_PAGE_STATUS_CLEAN); 1381 1382 /* 1383 * there wasn't a direct fault on the page, so avoid the cost of 1384 * activating it. 1385 */ 1386 1387 if (!uvmpdpol_pageisqueued_p(pg) && pg->wire_count == 0) { 1388 uvm_pagelock(pg); 1389 uvm_pageenqueue(pg); 1390 uvm_pageunlock(pg); 1391 } 1392 1393 UVMHIST_LOG(maphist, 1394 " MAPPING: n anon: pm=%#jx, va=%#jx, pg=%#jx", 1395 (uintptr_t)ufi->orig_map->pmap, currva, (uintptr_t)pg, 0); 1396 cpu_count(CPU_COUNT_FLTNAMAP, 1); 1397 1398 /* 1399 * Since this page isn't the page that's actually faulting, 1400 * ignore pmap_enter() failures; it's not critical that we 1401 * enter these right now. 1402 */ 1403 1404 (void) pmap_enter(ufi->orig_map->pmap, currva, 1405 VM_PAGE_TO_PHYS(pg), 1406 readonly ? (flt->enter_prot & ~VM_PROT_WRITE) : 1407 flt->enter_prot, 1408 PMAP_CANFAIL | (flt->wire_mapping ? PMAP_WIRED : 0)); 1409 } 1410 1411 /* 1412 * uvm_fault_upper: handle upper fault. 1413 * 1414 * 1. acquire anon lock. 1415 * 2. get anon. let uvmfault_anonget do the dirty work. 1416 * 3. handle loan. 1417 * 4. dispatch direct or promote handlers. 1418 */ 1419 1420 static int 1421 uvm_fault_upper( 1422 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1423 struct vm_anon **anons) 1424 { 1425 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1426 struct vm_anon * const anon = anons[flt->centeridx]; 1427 struct uvm_object *uobj; 1428 int error; 1429 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1430 1431 /* locked: maps(read), amap, anon */ 1432 KASSERT(rw_lock_op(amap->am_lock) == flt->upper_lock_type); 1433 KASSERT(anon->an_lock == amap->am_lock); 1434 1435 /* 1436 * handle case 1: fault on an anon in our amap 1437 */ 1438 1439 UVMHIST_LOG(maphist, " case 1 fault: anon=%#jx", 1440 (uintptr_t)anon, 0, 0, 0); 1441 1442 /* 1443 * no matter if we have case 1A or case 1B we are going to need to 1444 * have the anon's memory resident. ensure that now. 1445 */ 1446 1447 /* 1448 * let uvmfault_anonget do the dirty work. 1449 * if it fails (!OK) it will unlock everything for us. 1450 * if it succeeds, locks are still valid and locked. 1451 * also, if it is OK, then the anon's page is on the queues. 1452 * if the page is on loan from a uvm_object, then anonget will 1453 * lock that object for us if it does not fail. 1454 */ 1455 retry: 1456 error = uvmfault_anonget(ufi, amap, anon); 1457 switch (error) { 1458 case 0: 1459 break; 1460 1461 case ERESTART: 1462 return ERESTART; 1463 1464 case EAGAIN: 1465 kpause("fltagain1", false, hz/2, NULL); 1466 return ERESTART; 1467 1468 case ENOLCK: 1469 /* it needs a write lock: retry */ 1470 error = uvm_fault_upper_upgrade(ufi, flt, amap, NULL); 1471 if (error != 0) { 1472 return error; 1473 } 1474 KASSERT(rw_write_held(amap->am_lock)); 1475 goto retry; 1476 1477 default: 1478 return error; 1479 } 1480 1481 /* 1482 * uobj is non null if the page is on loan from an object (i.e. uobj) 1483 */ 1484 1485 uobj = anon->an_page->uobject; /* locked by anonget if !NULL */ 1486 1487 /* locked: maps(read), amap, anon, uobj(if one) */ 1488 KASSERT(rw_lock_op(amap->am_lock) == flt->upper_lock_type); 1489 KASSERT(anon->an_lock == amap->am_lock); 1490 KASSERT(uobj == NULL || 1491 rw_lock_op(uobj->vmobjlock) == flt->lower_lock_type); 1492 1493 /* 1494 * special handling for loaned pages 1495 */ 1496 1497 if (anon->an_page->loan_count) { 1498 error = uvm_fault_upper_loan(ufi, flt, anon, &uobj); 1499 if (error != 0) 1500 return error; 1501 } 1502 1503 /* 1504 * if we are case 1B then we will need to allocate a new blank 1505 * anon to transfer the data into. note that we have a lock 1506 * on anon, so no one can busy or release the page until we are done. 1507 * also note that the ref count can't drop to zero here because 1508 * it is > 1 and we are only dropping one ref. 1509 * 1510 * in the (hopefully very rare) case that we are out of RAM we 1511 * will unlock, wait for more RAM, and refault. 1512 * 1513 * if we are out of anon VM we kill the process (XXX: could wait?). 1514 */ 1515 1516 if (flt->cow_now && anon->an_ref > 1) { 1517 flt->promote = true; 1518 error = uvm_fault_upper_promote(ufi, flt, uobj, anon); 1519 } else { 1520 error = uvm_fault_upper_direct(ufi, flt, uobj, anon); 1521 } 1522 return error; 1523 } 1524 1525 /* 1526 * uvm_fault_upper_loan: handle loaned upper page. 1527 * 1528 * 1. if not cow'ing now, simply adjust flt->enter_prot. 1529 * 2. if cow'ing now, and if ref count is 1, break loan. 1530 */ 1531 1532 static int 1533 uvm_fault_upper_loan( 1534 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1535 struct vm_anon *anon, struct uvm_object **ruobj) 1536 { 1537 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1538 int error = 0; 1539 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1540 1541 if (!flt->cow_now) { 1542 1543 /* 1544 * for read faults on loaned pages we just cap the 1545 * protection at read-only. 1546 */ 1547 1548 flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; 1549 1550 } else { 1551 /* 1552 * note that we can't allow writes into a loaned page! 1553 * 1554 * if we have a write fault on a loaned page in an 1555 * anon then we need to look at the anon's ref count. 1556 * if it is greater than one then we are going to do 1557 * a normal copy-on-write fault into a new anon (this 1558 * is not a problem). however, if the reference count 1559 * is one (a case where we would normally allow a 1560 * write directly to the page) then we need to kill 1561 * the loan before we continue. 1562 */ 1563 1564 /* >1 case is already ok */ 1565 if (anon->an_ref == 1) { 1566 /* breaking loan requires a write lock. */ 1567 error = uvm_fault_upper_upgrade(ufi, flt, amap, NULL); 1568 if (error != 0) { 1569 return error; 1570 } 1571 KASSERT(rw_write_held(amap->am_lock)); 1572 1573 error = uvm_loanbreak_anon(anon, *ruobj); 1574 if (error != 0) { 1575 uvmfault_unlockall(ufi, amap, *ruobj); 1576 uvm_wait("flt_noram2"); 1577 return ERESTART; 1578 } 1579 /* if we were a loan receiver uobj is gone */ 1580 if (*ruobj) 1581 *ruobj = NULL; 1582 } 1583 } 1584 return error; 1585 } 1586 1587 /* 1588 * uvm_fault_upper_promote: promote upper page. 1589 * 1590 * 1. call uvmfault_promote. 1591 * 2. enqueue page. 1592 * 3. deref. 1593 * 4. pass page to uvm_fault_upper_enter. 1594 */ 1595 1596 static int 1597 uvm_fault_upper_promote( 1598 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1599 struct uvm_object *uobj, struct vm_anon *anon) 1600 { 1601 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1602 struct vm_anon * const oanon = anon; 1603 struct vm_page *pg; 1604 int error; 1605 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1606 1607 UVMHIST_LOG(maphist, " case 1B: COW fault",0,0,0,0); 1608 cpu_count(CPU_COUNT_FLT_ACOW, 1); 1609 1610 /* promoting requires a write lock. */ 1611 error = uvm_fault_upper_upgrade(ufi, flt, amap, NULL); 1612 if (error != 0) { 1613 return error; 1614 } 1615 KASSERT(rw_write_held(amap->am_lock)); 1616 1617 error = uvmfault_promote(ufi, oanon, PGO_DONTCARE, &anon, 1618 &flt->anon_spare); 1619 switch (error) { 1620 case 0: 1621 break; 1622 case ERESTART: 1623 return ERESTART; 1624 default: 1625 return error; 1626 } 1627 pg = anon->an_page; 1628 1629 KASSERT(anon->an_lock == oanon->an_lock); 1630 KASSERT((pg->flags & (PG_BUSY | PG_FAKE)) == 0); 1631 1632 /* deref: can not drop to zero here by defn! */ 1633 KASSERT(oanon->an_ref > 1); 1634 oanon->an_ref--; 1635 1636 /* 1637 * note: oanon is still locked, as is the new anon. we 1638 * need to check for this later when we unlock oanon; if 1639 * oanon != anon, we'll have to unlock anon, too. 1640 */ 1641 1642 return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon); 1643 } 1644 1645 /* 1646 * uvm_fault_upper_direct: handle direct fault. 1647 */ 1648 1649 static int 1650 uvm_fault_upper_direct( 1651 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1652 struct uvm_object *uobj, struct vm_anon *anon) 1653 { 1654 struct vm_anon * const oanon = anon; 1655 struct vm_page *pg; 1656 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1657 1658 cpu_count(CPU_COUNT_FLT_ANON, 1); 1659 pg = anon->an_page; 1660 if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */ 1661 flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; 1662 1663 return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon); 1664 } 1665 1666 /* 1667 * uvm_fault_upper_enter: enter h/w mapping of upper page. 1668 */ 1669 1670 static int 1671 uvm_fault_upper_enter( 1672 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1673 struct uvm_object *uobj, struct vm_anon *anon, struct vm_page *pg, 1674 struct vm_anon *oanon) 1675 { 1676 struct pmap *pmap = ufi->orig_map->pmap; 1677 vaddr_t va = ufi->orig_rvaddr; 1678 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1679 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1680 1681 /* locked: maps(read), amap, oanon, anon(if different from oanon) */ 1682 KASSERT(rw_lock_op(amap->am_lock) == flt->upper_lock_type); 1683 KASSERT(anon->an_lock == amap->am_lock); 1684 KASSERT(oanon->an_lock == amap->am_lock); 1685 KASSERT(uobj == NULL || 1686 rw_lock_op(uobj->vmobjlock) == flt->lower_lock_type); 1687 KASSERT(uvm_pagegetdirty(pg) != UVM_PAGE_STATUS_CLEAN); 1688 1689 /* 1690 * now map the page in. 1691 */ 1692 1693 UVMHIST_LOG(maphist, 1694 " MAPPING: anon: pm=%#jx, va=%#jx, pg=%#jx, promote=%jd", 1695 (uintptr_t)pmap, va, (uintptr_t)pg, flt->promote); 1696 if (pmap_enter(pmap, va, VM_PAGE_TO_PHYS(pg), 1697 flt->enter_prot, flt->access_type | PMAP_CANFAIL | 1698 (flt->wire_mapping ? PMAP_WIRED : 0)) != 0) { 1699 1700 /* 1701 * If pmap_enter() fails, it must not leave behind an existing 1702 * pmap entry. In particular, a now-stale entry for a different 1703 * page would leave the pmap inconsistent with the vm_map. 1704 * This is not to imply that pmap_enter() should remove an 1705 * existing mapping in such a situation (since that could create 1706 * different problems, eg. if the existing mapping is wired), 1707 * but rather that the pmap should be designed such that it 1708 * never needs to fail when the new mapping is replacing an 1709 * existing mapping and the new page has no existing mappings. 1710 * 1711 * XXX This can't be asserted safely any more because many 1712 * LWPs and/or many processes could simultaneously fault on 1713 * the same VA and some might succeed. 1714 */ 1715 1716 /* KASSERT(!pmap_extract(pmap, va, NULL)); */ 1717 1718 /* 1719 * ensure that the page is queued in the case that 1720 * we just promoted. 1721 */ 1722 1723 uvm_pagelock(pg); 1724 uvm_pageenqueue(pg); 1725 uvm_pageunlock(pg); 1726 1727 /* 1728 * No need to undo what we did; we can simply think of 1729 * this as the pmap throwing away the mapping information. 1730 * 1731 * We do, however, have to go through the ReFault path, 1732 * as the map may change while we're asleep. 1733 */ 1734 1735 uvmfault_unlockall(ufi, amap, uobj); 1736 if (!uvm_reclaimable()) { 1737 UVMHIST_LOG(maphist, 1738 "<- failed. out of VM",0,0,0,0); 1739 /* XXX instrumentation */ 1740 return ENOMEM; 1741 } 1742 /* XXX instrumentation */ 1743 uvm_wait("flt_pmfail1"); 1744 return ERESTART; 1745 } 1746 1747 uvm_fault_upper_done(ufi, flt, anon, pg); 1748 1749 /* 1750 * done case 1! finish up by unlocking everything and returning success 1751 */ 1752 1753 pmap_update(pmap); 1754 uvmfault_unlockall(ufi, amap, uobj); 1755 return 0; 1756 } 1757 1758 /* 1759 * uvm_fault_upper_done: queue upper center page. 1760 */ 1761 1762 static void 1763 uvm_fault_upper_done( 1764 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1765 struct vm_anon *anon, struct vm_page *pg) 1766 { 1767 const bool wire_paging = flt->wire_paging; 1768 1769 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1770 1771 /* 1772 * ... update the page queues. 1773 */ 1774 1775 if (wire_paging) { 1776 uvm_pagelock(pg); 1777 uvm_pagewire(pg); 1778 uvm_pageunlock(pg); 1779 1780 /* 1781 * since the now-wired page cannot be paged out, 1782 * release its swap resources for others to use. 1783 * and since an anon with no swap cannot be clean, 1784 * mark it dirty now. 1785 */ 1786 1787 uvm_pagemarkdirty(pg, UVM_PAGE_STATUS_DIRTY); 1788 uvm_anon_dropswap(anon); 1789 } else if (uvmpdpol_pageactivate_p(pg)) { 1790 /* 1791 * avoid re-activating the page unless needed, 1792 * to avoid false sharing on multiprocessor. 1793 */ 1794 1795 uvm_pagelock(pg); 1796 uvm_pageactivate(pg); 1797 uvm_pageunlock(pg); 1798 } 1799 } 1800 1801 /* 1802 * uvm_fault_lower_upgrade: upgrade lower lock, reader -> writer 1803 */ 1804 1805 static inline int 1806 uvm_fault_lower_upgrade(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1807 struct vm_amap *amap, struct uvm_object *uobj, struct vm_page *uobjpage) 1808 { 1809 1810 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1811 1812 KASSERT(uobj != NULL); 1813 KASSERT(flt->lower_lock_type == rw_lock_op(uobj->vmobjlock)); 1814 1815 /* 1816 * fast path. 1817 */ 1818 1819 if (__predict_true(flt->lower_lock_type == RW_WRITER)) { 1820 return 0; 1821 } 1822 1823 /* 1824 * otherwise try for the upgrade. if we don't get it, unlock 1825 * everything, restart the fault and next time around get a writer 1826 * lock. 1827 */ 1828 1829 flt->lower_lock_type = RW_WRITER; 1830 if (__predict_false(!rw_tryupgrade(uobj->vmobjlock))) { 1831 uvmfault_unlockall(ufi, amap, uobj); 1832 cpu_count(CPU_COUNT_FLTNOUP, 1); 1833 UVMHIST_LOG(maphist, " !upgrade lower", 0, 0,0,0); 1834 return ERESTART; 1835 } 1836 cpu_count(CPU_COUNT_FLTUP, 1); 1837 KASSERT(flt->lower_lock_type == rw_lock_op(uobj->vmobjlock)); 1838 return 0; 1839 } 1840 1841 /* 1842 * uvm_fault_lower: handle lower fault. 1843 * 1844 * 1. check uobj 1845 * 1.1. if null, ZFOD. 1846 * 1.2. if not null, look up unnmapped neighbor pages. 1847 * 2. for center page, check if promote. 1848 * 2.1. ZFOD always needs promotion. 1849 * 2.2. other uobjs, when entry is marked COW (usually MAP_PRIVATE vnode). 1850 * 3. if uobj is not ZFOD and page is not found, do i/o. 1851 * 4. dispatch either direct / promote fault. 1852 */ 1853 1854 static int 1855 uvm_fault_lower( 1856 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1857 struct vm_page **pages) 1858 { 1859 struct vm_amap *amap __diagused = ufi->entry->aref.ar_amap; 1860 struct uvm_object *uobj = ufi->entry->object.uvm_obj; 1861 struct vm_page *uobjpage; 1862 int error; 1863 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1864 1865 /* 1866 * now, if the desired page is not shadowed by the amap and we have 1867 * a backing object that does not have a special fault routine, then 1868 * we ask (with pgo_get) the object for resident pages that we care 1869 * about and attempt to map them in. we do not let pgo_get block 1870 * (PGO_LOCKED). 1871 */ 1872 1873 if (uobj == NULL) { 1874 /* zero fill; don't care neighbor pages */ 1875 uobjpage = NULL; 1876 } else { 1877 uvm_fault_lower_lookup(ufi, flt, pages); 1878 uobjpage = pages[flt->centeridx]; 1879 } 1880 1881 /* 1882 * note that at this point we are done with any front or back pages. 1883 * we are now going to focus on the center page (i.e. the one we've 1884 * faulted on). if we have faulted on the upper (anon) layer 1885 * [i.e. case 1], then the anon we want is anons[centeridx] (we have 1886 * not touched it yet). if we have faulted on the bottom (uobj) 1887 * layer [i.e. case 2] and the page was both present and available, 1888 * then we've got a pointer to it as "uobjpage" and we've already 1889 * made it BUSY. 1890 */ 1891 1892 /* 1893 * locked: 1894 * maps(read), amap(if there), uobj(if !null), uobjpage(if !null) 1895 */ 1896 KASSERT(amap == NULL || 1897 rw_lock_op(amap->am_lock) == flt->upper_lock_type); 1898 KASSERT(uobj == NULL || 1899 rw_lock_op(uobj->vmobjlock) == flt->lower_lock_type); 1900 1901 /* 1902 * note that uobjpage can not be PGO_DONTCARE at this point. we now 1903 * set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we 1904 * have a backing object, check and see if we are going to promote 1905 * the data up to an anon during the fault. 1906 */ 1907 1908 if (uobj == NULL) { 1909 uobjpage = PGO_DONTCARE; 1910 flt->promote = true; /* always need anon here */ 1911 } else { 1912 KASSERT(uobjpage != PGO_DONTCARE); 1913 flt->promote = flt->cow_now && UVM_ET_ISCOPYONWRITE(ufi->entry); 1914 } 1915 UVMHIST_LOG(maphist, " case 2 fault: promote=%jd, zfill=%jd", 1916 flt->promote, (uobj == NULL), 0,0); 1917 1918 /* 1919 * if uobjpage is not null then we do not need to do I/O to get the 1920 * uobjpage. 1921 * 1922 * if uobjpage is null, then we need to unlock and ask the pager to 1923 * get the data for us. once we have the data, we need to reverify 1924 * the state the world. we are currently not holding any resources. 1925 */ 1926 1927 if (uobjpage) { 1928 /* update rusage counters */ 1929 curlwp->l_ru.ru_minflt++; 1930 } else { 1931 error = uvm_fault_lower_io(ufi, flt, &uobj, &uobjpage); 1932 if (error != 0) 1933 return error; 1934 } 1935 1936 /* 1937 * locked: 1938 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj) 1939 */ 1940 KASSERT(amap == NULL || 1941 rw_lock_op(amap->am_lock) == flt->upper_lock_type); 1942 KASSERT(uobj == NULL || 1943 rw_lock_op(uobj->vmobjlock) == flt->lower_lock_type); 1944 1945 /* 1946 * notes: 1947 * - at this point uobjpage can not be NULL 1948 * - at this point uobjpage can not be PG_RELEASED (since we checked 1949 * for it above) 1950 * - at this point uobjpage could be waited on (handle later) 1951 * - uobjpage can be from a different object if tmpfs (vnode vs UAO) 1952 */ 1953 1954 KASSERT(uobjpage != NULL); 1955 KASSERT(uobj == NULL || 1956 uobjpage->uobject->vmobjlock == uobj->vmobjlock); 1957 KASSERT(uobj == NULL || !UVM_OBJ_IS_CLEAN(uobjpage->uobject) || 1958 uvm_pagegetdirty(uobjpage) == UVM_PAGE_STATUS_CLEAN); 1959 1960 if (!flt->promote) { 1961 error = uvm_fault_lower_direct(ufi, flt, uobj, uobjpage); 1962 } else { 1963 error = uvm_fault_lower_promote(ufi, flt, uobj, uobjpage); 1964 } 1965 return error; 1966 } 1967 1968 /* 1969 * uvm_fault_lower_lookup: look up on-memory uobj pages. 1970 * 1971 * 1. get on-memory pages. 1972 * 2. if failed, give up (get only center page later). 1973 * 3. if succeeded, enter h/w mapping of neighbor pages. 1974 */ 1975 1976 static void 1977 uvm_fault_lower_lookup( 1978 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1979 struct vm_page **pages) 1980 { 1981 struct uvm_object *uobj = ufi->entry->object.uvm_obj; 1982 int lcv, gotpages; 1983 vaddr_t currva; 1984 bool entered; 1985 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1986 1987 rw_enter(uobj->vmobjlock, flt->lower_lock_type); 1988 1989 /* 1990 * Locked: maps(read), amap(if there), uobj 1991 */ 1992 1993 cpu_count(CPU_COUNT_FLTLGET, 1); 1994 gotpages = flt->npages; 1995 (void) uobj->pgops->pgo_get(uobj, 1996 ufi->entry->offset + flt->startva - ufi->entry->start, 1997 pages, &gotpages, flt->centeridx, 1998 flt->access_type & MASK(ufi->entry), ufi->entry->advice, 1999 PGO_LOCKED); 2000 2001 KASSERT(rw_lock_op(uobj->vmobjlock) == flt->lower_lock_type); 2002 2003 /* 2004 * check for pages to map, if we got any 2005 */ 2006 2007 if (gotpages == 0) { 2008 pages[flt->centeridx] = NULL; 2009 return; 2010 } 2011 2012 entered = false; 2013 currva = flt->startva; 2014 for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { 2015 struct vm_page *curpg; 2016 2017 curpg = pages[lcv]; 2018 if (curpg == NULL || curpg == PGO_DONTCARE) { 2019 continue; 2020 } 2021 2022 /* 2023 * in the case of tmpfs, the pages might be from a different 2024 * uvm_object. just make sure that they have the same lock. 2025 */ 2026 2027 KASSERT(curpg->uobject->vmobjlock == uobj->vmobjlock); 2028 KASSERT((curpg->flags & PG_BUSY) == 0); 2029 2030 /* 2031 * leave the centre page for later. don't screw with 2032 * existing mappings (needless & expensive). 2033 */ 2034 2035 if (lcv == flt->centeridx) { 2036 UVMHIST_LOG(maphist, " got uobjpage (%#jx) " 2037 "with locked get", (uintptr_t)curpg, 0, 0, 0); 2038 } else if (!pmap_extract(ufi->orig_map->pmap, currva, NULL)) { 2039 uvm_fault_lower_neighbor(ufi, flt, currva, curpg); 2040 entered = true; 2041 } 2042 } 2043 if (entered) { 2044 pmap_update(ufi->orig_map->pmap); 2045 } 2046 } 2047 2048 /* 2049 * uvm_fault_lower_neighbor: enter h/w mapping of lower neighbor page. 2050 */ 2051 2052 static void 2053 uvm_fault_lower_neighbor( 2054 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 2055 vaddr_t currva, struct vm_page *pg) 2056 { 2057 const bool readonly = uvm_pagereadonly_p(pg) || pg->loan_count > 0; 2058 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 2059 2060 /* locked: maps(read), amap(if there), uobj */ 2061 2062 /* 2063 * calling pgo_get with PGO_LOCKED returns us pages which 2064 * are neither busy nor released, so we don't need to check 2065 * for this. we can just directly enter the pages. 2066 * 2067 * there wasn't a direct fault on the page, so avoid the cost of 2068 * activating it. 2069 */ 2070 2071 if (!uvmpdpol_pageisqueued_p(pg) && pg->wire_count == 0) { 2072 uvm_pagelock(pg); 2073 uvm_pageenqueue(pg); 2074 uvm_pageunlock(pg); 2075 } 2076 2077 UVMHIST_LOG(maphist, 2078 " MAPPING: n obj: pm=%#jx, va=%#jx, pg=%#jx", 2079 (uintptr_t)ufi->orig_map->pmap, currva, (uintptr_t)pg, 0); 2080 cpu_count(CPU_COUNT_FLTNOMAP, 1); 2081 2082 /* 2083 * Since this page isn't the page that's actually faulting, 2084 * ignore pmap_enter() failures; it's not critical that we 2085 * enter these right now. 2086 * NOTE: page can't be waited on or PG_RELEASED because we've 2087 * held the lock the whole time we've had the handle. 2088 */ 2089 KASSERT((pg->flags & PG_PAGEOUT) == 0); 2090 KASSERT((pg->flags & PG_RELEASED) == 0); 2091 KASSERT(!UVM_OBJ_IS_CLEAN(pg->uobject) || 2092 uvm_pagegetdirty(pg) == UVM_PAGE_STATUS_CLEAN); 2093 KASSERT((pg->flags & PG_BUSY) == 0); 2094 KASSERT(rw_lock_op(pg->uobject->vmobjlock) == flt->lower_lock_type); 2095 2096 const vm_prot_t mapprot = 2097 readonly ? (flt->enter_prot & ~VM_PROT_WRITE) : 2098 flt->enter_prot & MASK(ufi->entry); 2099 const u_int mapflags = 2100 PMAP_CANFAIL | (flt->wire_mapping ? (mapprot | PMAP_WIRED) : 0); 2101 (void) pmap_enter(ufi->orig_map->pmap, currva, 2102 VM_PAGE_TO_PHYS(pg), mapprot, mapflags); 2103 } 2104 2105 /* 2106 * uvm_fault_lower_io: get lower page from backing store. 2107 * 2108 * 1. unlock everything, because i/o will block. 2109 * 2. call pgo_get. 2110 * 3. if failed, recover. 2111 * 4. if succeeded, relock everything and verify things. 2112 */ 2113 2114 static int 2115 uvm_fault_lower_io( 2116 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 2117 struct uvm_object **ruobj, struct vm_page **ruobjpage) 2118 { 2119 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 2120 struct uvm_object *uobj = *ruobj; 2121 struct vm_page *pg; 2122 bool locked; 2123 int gotpages; 2124 int error; 2125 voff_t uoff; 2126 vm_prot_t access_type; 2127 int advice; 2128 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 2129 2130 /* update rusage counters */ 2131 curlwp->l_ru.ru_majflt++; 2132 2133 /* grab everything we need from the entry before we unlock */ 2134 uoff = (ufi->orig_rvaddr - ufi->entry->start) + ufi->entry->offset; 2135 access_type = flt->access_type & MASK(ufi->entry); 2136 advice = ufi->entry->advice; 2137 2138 /* Locked: maps(read), amap(if there), uobj */ 2139 KASSERT(rw_lock_op(uobj->vmobjlock) == flt->lower_lock_type); 2140 2141 /* Upgrade to a write lock if needed. */ 2142 error = uvm_fault_lower_upgrade(ufi, flt, amap, uobj, NULL); 2143 if (error != 0) { 2144 return error; 2145 } 2146 uvmfault_unlockall(ufi, amap, NULL); 2147 2148 /* Locked: uobj(write) */ 2149 KASSERT(rw_write_held(uobj->vmobjlock)); 2150 2151 cpu_count(CPU_COUNT_FLTGET, 1); 2152 gotpages = 1; 2153 pg = NULL; 2154 error = uobj->pgops->pgo_get(uobj, uoff, &pg, &gotpages, 2155 0, access_type, advice, PGO_SYNCIO); 2156 /* locked: pg(if no error) */ 2157 2158 /* 2159 * recover from I/O 2160 */ 2161 2162 if (error) { 2163 if (error == EAGAIN) { 2164 UVMHIST_LOG(maphist, 2165 " pgo_get says TRY AGAIN!",0,0,0,0); 2166 kpause("fltagain2", false, hz/2, NULL); 2167 return ERESTART; 2168 } 2169 2170 #if 0 2171 KASSERT(error != ERESTART); 2172 #else 2173 /* XXXUEBS don't re-fault? */ 2174 if (error == ERESTART) 2175 error = EIO; 2176 #endif 2177 2178 UVMHIST_LOG(maphist, "<- pgo_get failed (code %jd)", 2179 error, 0,0,0); 2180 return error; 2181 } 2182 2183 /* 2184 * re-verify the state of the world by first trying to relock 2185 * the maps. always relock the object. 2186 */ 2187 2188 locked = uvmfault_relock(ufi); 2189 if (locked && amap) 2190 amap_lock(amap, flt->upper_lock_type); 2191 2192 /* might be changed */ 2193 uobj = pg->uobject; 2194 2195 rw_enter(uobj->vmobjlock, flt->lower_lock_type); 2196 KASSERT((pg->flags & PG_BUSY) != 0); 2197 KASSERT(flt->lower_lock_type == RW_WRITER); 2198 2199 uvm_pagelock(pg); 2200 uvm_pageactivate(pg); 2201 uvm_pageunlock(pg); 2202 2203 /* locked(locked): maps(read), amap(if !null), uobj, pg */ 2204 /* locked(!locked): uobj, pg */ 2205 2206 /* 2207 * verify that the page has not be released and re-verify 2208 * that amap slot is still free. if there is a problem, 2209 * we unlock and clean up. 2210 */ 2211 2212 if ((pg->flags & PG_RELEASED) != 0 || 2213 (locked && amap && amap_lookup(&ufi->entry->aref, 2214 ufi->orig_rvaddr - ufi->entry->start))) { 2215 if (locked) 2216 uvmfault_unlockall(ufi, amap, NULL); 2217 locked = false; 2218 } 2219 2220 /* 2221 * unbusy/release the page. 2222 */ 2223 2224 if ((pg->flags & PG_RELEASED) == 0) { 2225 pg->flags &= ~PG_BUSY; 2226 uvm_pagelock(pg); 2227 uvm_pagewakeup(pg); 2228 uvm_pageunlock(pg); 2229 UVM_PAGE_OWN(pg, NULL); 2230 } else { 2231 cpu_count(CPU_COUNT_FLTPGRELE, 1); 2232 uvm_pagefree(pg); 2233 } 2234 2235 /* 2236 * didn't get the lock? retry. 2237 */ 2238 2239 if (locked == false) { 2240 UVMHIST_LOG(maphist, 2241 " wasn't able to relock after fault: retry", 2242 0,0,0,0); 2243 rw_exit(uobj->vmobjlock); 2244 return ERESTART; 2245 } 2246 2247 /* 2248 * we have the data in pg. we are holding object lock (so the page 2249 * can't be released on us). 2250 */ 2251 2252 /* locked: maps(read), amap(if !null), uobj */ 2253 2254 *ruobj = uobj; 2255 *ruobjpage = pg; 2256 return 0; 2257 } 2258 2259 /* 2260 * uvm_fault_lower_direct: fault lower center page 2261 * 2262 * 1. adjust flt->enter_prot. 2263 * 2. if page is loaned, resolve. 2264 */ 2265 2266 int 2267 uvm_fault_lower_direct( 2268 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 2269 struct uvm_object *uobj, struct vm_page *uobjpage) 2270 { 2271 struct vm_page *pg; 2272 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 2273 2274 /* 2275 * we are not promoting. if the mapping is COW ensure that we 2276 * don't give more access than we should (e.g. when doing a read 2277 * fault on a COPYONWRITE mapping we want to map the COW page in 2278 * R/O even though the entry protection could be R/W). 2279 * 2280 * set "pg" to the page we want to map in (uobjpage, usually) 2281 */ 2282 2283 cpu_count(CPU_COUNT_FLT_OBJ, 1); 2284 if (UVM_ET_ISCOPYONWRITE(ufi->entry) || 2285 UVM_OBJ_NEEDS_WRITEFAULT(uobjpage->uobject)) 2286 flt->enter_prot &= ~VM_PROT_WRITE; 2287 pg = uobjpage; /* map in the actual object */ 2288 2289 KASSERT(uobjpage != PGO_DONTCARE); 2290 2291 /* 2292 * we are faulting directly on the page. be careful 2293 * about writing to loaned pages... 2294 */ 2295 2296 if (uobjpage->loan_count) { 2297 uvm_fault_lower_direct_loan(ufi, flt, uobj, &pg, &uobjpage); 2298 } 2299 KASSERT(pg == uobjpage); 2300 KASSERT((pg->flags & PG_BUSY) == 0); 2301 return uvm_fault_lower_enter(ufi, flt, uobj, NULL, pg); 2302 } 2303 2304 /* 2305 * uvm_fault_lower_direct_loan: resolve loaned page. 2306 * 2307 * 1. if not cow'ing, adjust flt->enter_prot. 2308 * 2. if cow'ing, break loan. 2309 */ 2310 2311 static int 2312 uvm_fault_lower_direct_loan( 2313 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 2314 struct uvm_object *uobj, struct vm_page **rpg, 2315 struct vm_page **ruobjpage) 2316 { 2317 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 2318 struct vm_page *pg; 2319 struct vm_page *uobjpage = *ruobjpage; 2320 int error; 2321 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 2322 2323 if (!flt->cow_now) { 2324 /* read fault: cap the protection at readonly */ 2325 /* cap! */ 2326 flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; 2327 } else { 2328 /* 2329 * write fault: must break the loan here. to do this 2330 * we need a write lock on the object. 2331 */ 2332 2333 error = uvm_fault_lower_upgrade(ufi, flt, amap, uobj, uobjpage); 2334 if (error != 0) { 2335 return error; 2336 } 2337 KASSERT(rw_write_held(uobj->vmobjlock)); 2338 2339 pg = uvm_loanbreak(uobjpage); 2340 if (pg == NULL) { 2341 2342 uvmfault_unlockall(ufi, amap, uobj); 2343 UVMHIST_LOG(maphist, 2344 " out of RAM breaking loan, waiting", 2345 0,0,0,0); 2346 cpu_count(CPU_COUNT_FLTNORAM, 1); 2347 uvm_wait("flt_noram4"); 2348 return ERESTART; 2349 } 2350 *rpg = pg; 2351 *ruobjpage = pg; 2352 2353 /* 2354 * drop ownership of page while still holding object lock, 2355 * which won't be dropped until the page is entered. 2356 */ 2357 2358 uvm_pagelock(pg); 2359 uvm_pagewakeup(pg); 2360 uvm_pageunlock(pg); 2361 pg->flags &= ~PG_BUSY; 2362 UVM_PAGE_OWN(pg, NULL); 2363 } 2364 return 0; 2365 } 2366 2367 /* 2368 * uvm_fault_lower_promote: promote lower page. 2369 * 2370 * 1. call uvmfault_promote. 2371 * 2. fill in data. 2372 * 3. if not ZFOD, dispose old page. 2373 */ 2374 2375 int 2376 uvm_fault_lower_promote( 2377 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 2378 struct uvm_object *uobj, struct vm_page *uobjpage) 2379 { 2380 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 2381 struct vm_anon *anon; 2382 struct vm_page *pg; 2383 int error; 2384 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 2385 2386 KASSERT(amap != NULL); 2387 2388 /* promoting requires a write lock. */ 2389 error = uvm_fault_upper_upgrade(ufi, flt, amap, uobj); 2390 if (error != 0) { 2391 return error; 2392 } 2393 KASSERT(rw_write_held(amap->am_lock)); 2394 KASSERT(uobj == NULL || 2395 rw_lock_op(uobj->vmobjlock) == flt->lower_lock_type); 2396 2397 /* 2398 * If we are going to promote the data to an anon we 2399 * allocate a blank anon here and plug it into our amap. 2400 */ 2401 error = uvmfault_promote(ufi, NULL, uobjpage, &anon, &flt->anon_spare); 2402 switch (error) { 2403 case 0: 2404 break; 2405 case ERESTART: 2406 return ERESTART; 2407 default: 2408 return error; 2409 } 2410 2411 pg = anon->an_page; 2412 2413 /* 2414 * Fill in the data. 2415 */ 2416 2417 if (uobjpage != PGO_DONTCARE) { 2418 cpu_count(CPU_COUNT_FLT_PRCOPY, 1); 2419 2420 /* 2421 * promote to shared amap? make sure all sharing 2422 * procs see it 2423 */ 2424 2425 if ((amap_flags(amap) & AMAP_SHARED) != 0) { 2426 pmap_page_protect(uobjpage, VM_PROT_NONE); 2427 /* 2428 * XXX: PAGE MIGHT BE WIRED! 2429 */ 2430 } 2431 2432 UVMHIST_LOG(maphist, 2433 " promote uobjpage %#jx to anon/page %#jx/%#jx", 2434 (uintptr_t)uobjpage, (uintptr_t)anon, (uintptr_t)pg, 0); 2435 2436 } else { 2437 cpu_count(CPU_COUNT_FLT_PRZERO, 1); 2438 2439 /* 2440 * Page is zero'd and marked dirty by 2441 * uvmfault_promote(). 2442 */ 2443 2444 UVMHIST_LOG(maphist," zero fill anon/page %#jx/%#jx", 2445 (uintptr_t)anon, (uintptr_t)pg, 0, 0); 2446 } 2447 2448 return uvm_fault_lower_enter(ufi, flt, uobj, anon, pg); 2449 } 2450 2451 /* 2452 * uvm_fault_lower_enter: enter h/w mapping of lower page or anon page promoted 2453 * from the lower page. 2454 */ 2455 2456 int 2457 uvm_fault_lower_enter( 2458 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 2459 struct uvm_object *uobj, 2460 struct vm_anon *anon, struct vm_page *pg) 2461 { 2462 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 2463 const bool readonly = uvm_pagereadonly_p(pg); 2464 int error; 2465 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 2466 2467 /* 2468 * Locked: 2469 * 2470 * maps(read), amap(if !null), uobj(if !null), 2471 * anon(if !null), pg(if anon), unlock_uobj(if !null) 2472 * 2473 * anon must be write locked (promotion). uobj can be either. 2474 * 2475 * Note: pg is either the uobjpage or the new page in the new anon. 2476 */ 2477 2478 KASSERT(amap == NULL || 2479 rw_lock_op(amap->am_lock) == flt->upper_lock_type); 2480 KASSERT(uobj == NULL || 2481 rw_lock_op(uobj->vmobjlock) == flt->lower_lock_type); 2482 KASSERT(anon == NULL || anon->an_lock == amap->am_lock); 2483 2484 /* 2485 * note that pg can't be PG_RELEASED or PG_BUSY since we did 2486 * not drop the object lock since the last time we checked. 2487 */ 2488 2489 KASSERT((pg->flags & PG_RELEASED) == 0); 2490 KASSERT((pg->flags & PG_BUSY) == 0); 2491 2492 /* 2493 * all resources are present. we can now map it in and free our 2494 * resources. 2495 */ 2496 2497 UVMHIST_LOG(maphist, 2498 " MAPPING: case2: pm=%#jx, va=%#jx, pg=%#jx, promote=%jd", 2499 (uintptr_t)ufi->orig_map->pmap, ufi->orig_rvaddr, 2500 (uintptr_t)pg, flt->promote); 2501 KASSERTMSG((flt->access_type & VM_PROT_WRITE) == 0 || !readonly, 2502 "promote=%u cow_now=%u access_type=%x enter_prot=%x cow=%u " 2503 "entry=%p map=%p orig_rvaddr=%p pg=%p", 2504 flt->promote, flt->cow_now, flt->access_type, flt->enter_prot, 2505 UVM_ET_ISCOPYONWRITE(ufi->entry), ufi->entry, ufi->orig_map, 2506 (void *)ufi->orig_rvaddr, pg); 2507 KASSERT((flt->access_type & VM_PROT_WRITE) == 0 || !readonly); 2508 if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr, 2509 VM_PAGE_TO_PHYS(pg), 2510 readonly ? flt->enter_prot & ~VM_PROT_WRITE : flt->enter_prot, 2511 flt->access_type | PMAP_CANFAIL | 2512 (flt->wire_mapping ? PMAP_WIRED : 0)) != 0) { 2513 2514 /* 2515 * No need to undo what we did; we can simply think of 2516 * this as the pmap throwing away the mapping information. 2517 * 2518 * We do, however, have to go through the ReFault path, 2519 * as the map may change while we're asleep. 2520 */ 2521 2522 /* 2523 * ensure that the page is queued in the case that 2524 * we just promoted the page. 2525 */ 2526 2527 if (anon != NULL) { 2528 uvm_pagelock(pg); 2529 uvm_pageenqueue(pg); 2530 uvm_pagewakeup(pg); 2531 uvm_pageunlock(pg); 2532 } 2533 2534 uvmfault_unlockall(ufi, amap, uobj); 2535 if (!uvm_reclaimable()) { 2536 UVMHIST_LOG(maphist, 2537 "<- failed. out of VM",0,0,0,0); 2538 /* XXX instrumentation */ 2539 error = ENOMEM; 2540 return error; 2541 } 2542 /* XXX instrumentation */ 2543 uvm_wait("flt_pmfail2"); 2544 return ERESTART; 2545 } 2546 2547 uvm_fault_lower_done(ufi, flt, uobj, pg); 2548 pmap_update(ufi->orig_map->pmap); 2549 uvmfault_unlockall(ufi, amap, uobj); 2550 2551 UVMHIST_LOG(maphist, "<- done (SUCCESS!)",0,0,0,0); 2552 return 0; 2553 } 2554 2555 /* 2556 * uvm_fault_lower_done: queue lower center page. 2557 */ 2558 2559 void 2560 uvm_fault_lower_done( 2561 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 2562 struct uvm_object *uobj, struct vm_page *pg) 2563 { 2564 2565 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 2566 2567 if (flt->wire_paging) { 2568 uvm_pagelock(pg); 2569 uvm_pagewire(pg); 2570 uvm_pageunlock(pg); 2571 if (pg->flags & PG_AOBJ) { 2572 2573 /* 2574 * since the now-wired page cannot be paged out, 2575 * release its swap resources for others to use. 2576 * since an aobj page with no swap cannot be clean, 2577 * mark it dirty now. 2578 * 2579 * use pg->uobject here. if the page is from a 2580 * tmpfs vnode, the pages are backed by its UAO and 2581 * not the vnode. 2582 */ 2583 2584 KASSERT(uobj != NULL); 2585 KASSERT(uobj->vmobjlock == pg->uobject->vmobjlock); 2586 uvm_pagemarkdirty(pg, UVM_PAGE_STATUS_DIRTY); 2587 uao_dropswap(pg->uobject, pg->offset >> PAGE_SHIFT); 2588 } 2589 } else if (uvmpdpol_pageactivate_p(pg)) { 2590 /* 2591 * avoid re-activating the page unless needed, 2592 * to avoid false sharing on multiprocessor. 2593 */ 2594 2595 uvm_pagelock(pg); 2596 uvm_pageactivate(pg); 2597 uvm_pageunlock(pg); 2598 } 2599 } 2600 2601 2602 /* 2603 * uvm_fault_wire: wire down a range of virtual addresses in a map. 2604 * 2605 * => map may be read-locked by caller, but MUST NOT be write-locked. 2606 * => if map is read-locked, any operations which may cause map to 2607 * be write-locked in uvm_fault() must be taken care of by 2608 * the caller. See uvm_map_pageable(). 2609 */ 2610 2611 int 2612 uvm_fault_wire(struct vm_map *map, vaddr_t start, vaddr_t end, 2613 vm_prot_t access_type, int maxprot) 2614 { 2615 vaddr_t va; 2616 int error; 2617 2618 /* 2619 * now fault it in a page at a time. if the fault fails then we have 2620 * to undo what we have done. note that in uvm_fault VM_PROT_NONE 2621 * is replaced with the max protection if fault_type is VM_FAULT_WIRE. 2622 */ 2623 2624 /* 2625 * XXX work around overflowing a vaddr_t. this prevents us from 2626 * wiring the last page in the address space, though. 2627 */ 2628 if (start > end) { 2629 return EFAULT; 2630 } 2631 2632 for (va = start; va < end; va += PAGE_SIZE) { 2633 error = uvm_fault_internal(map, va, access_type, 2634 (maxprot ? UVM_FAULT_MAXPROT : 0) | UVM_FAULT_WIRE); 2635 if (error) { 2636 if (va != start) { 2637 uvm_fault_unwire(map, start, va); 2638 } 2639 return error; 2640 } 2641 } 2642 return 0; 2643 } 2644 2645 /* 2646 * uvm_fault_unwire(): unwire range of virtual space. 2647 */ 2648 2649 void 2650 uvm_fault_unwire(struct vm_map *map, vaddr_t start, vaddr_t end) 2651 { 2652 vm_map_lock_read(map); 2653 uvm_fault_unwire_locked(map, start, end); 2654 vm_map_unlock_read(map); 2655 } 2656 2657 /* 2658 * uvm_fault_unwire_locked(): the guts of uvm_fault_unwire(). 2659 * 2660 * => map must be at least read-locked. 2661 */ 2662 2663 void 2664 uvm_fault_unwire_locked(struct vm_map *map, vaddr_t start, vaddr_t end) 2665 { 2666 struct vm_map_entry *entry, *oentry; 2667 pmap_t pmap = vm_map_pmap(map); 2668 vaddr_t va; 2669 paddr_t pa; 2670 struct vm_page *pg; 2671 2672 /* 2673 * we assume that the area we are unwiring has actually been wired 2674 * in the first place. this means that we should be able to extract 2675 * the PAs from the pmap. we also lock out the page daemon so that 2676 * we can call uvm_pageunwire. 2677 */ 2678 2679 /* 2680 * find the beginning map entry for the region. 2681 */ 2682 2683 KASSERT(start >= vm_map_min(map)); 2684 KASSERT(end <= vm_map_max(map)); 2685 if (uvm_map_lookup_entry(map, start, &entry) == false) 2686 panic("uvm_fault_unwire_locked: address not in map"); 2687 2688 oentry = NULL; 2689 for (va = start; va < end; va += PAGE_SIZE) { 2690 2691 /* 2692 * find the map entry for the current address. 2693 */ 2694 2695 KASSERT(va >= entry->start); 2696 while (va >= entry->end) { 2697 KASSERT(entry->next != &map->header); 2698 KASSERT(entry->next->start <= entry->end); 2699 entry = entry->next; 2700 } 2701 2702 /* 2703 * lock it. 2704 */ 2705 2706 if (entry != oentry) { 2707 if (oentry != NULL) { 2708 uvm_map_unlock_entry(oentry); 2709 } 2710 uvm_map_lock_entry(entry, RW_WRITER); 2711 oentry = entry; 2712 } 2713 2714 /* 2715 * if the entry is no longer wired, tell the pmap. 2716 */ 2717 2718 if (!pmap_extract(pmap, va, &pa)) 2719 continue; 2720 2721 if (VM_MAPENT_ISWIRED(entry) == 0) 2722 pmap_unwire(pmap, va); 2723 2724 pg = PHYS_TO_VM_PAGE(pa); 2725 if (pg) { 2726 uvm_pagelock(pg); 2727 uvm_pageunwire(pg); 2728 uvm_pageunlock(pg); 2729 } 2730 } 2731 2732 if (oentry != NULL) { 2733 uvm_map_unlock_entry(entry); 2734 } 2735 } 2736