1 /* $NetBSD: uvm_fault.c,v 1.194 2012/02/19 00:05:55 rmind 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 1.194 2012/02/19 00:05:55 rmind Exp $"); 36 37 #include "opt_uvmhist.h" 38 39 #include <sys/param.h> 40 #include <sys/systm.h> 41 #include <sys/kernel.h> 42 #include <sys/mman.h> 43 44 #include <uvm/uvm.h> 45 46 /* 47 * 48 * a word on page faults: 49 * 50 * types of page faults we handle: 51 * 52 * CASE 1: upper layer faults CASE 2: lower layer faults 53 * 54 * CASE 1A CASE 1B CASE 2A CASE 2B 55 * read/write1 write>1 read/write +-cow_write/zero 56 * | | | | 57 * +--|--+ +--|--+ +-----+ + | + | +-----+ 58 * amap | V | | ---------> new | | | | ^ | 59 * +-----+ +-----+ +-----+ + | + | +--|--+ 60 * | | | 61 * +-----+ +-----+ +--|--+ | +--|--+ 62 * uobj | d/c | | d/c | | V | +----+ | 63 * +-----+ +-----+ +-----+ +-----+ 64 * 65 * d/c = don't care 66 * 67 * case [0]: layerless fault 68 * no amap or uobj is present. this is an error. 69 * 70 * case [1]: upper layer fault [anon active] 71 * 1A: [read] or [write with anon->an_ref == 1] 72 * I/O takes place in upper level anon and uobj is not touched. 73 * 1B: [write with anon->an_ref > 1] 74 * new anon is alloc'd and data is copied off ["COW"] 75 * 76 * case [2]: lower layer fault [uobj] 77 * 2A: [read on non-NULL uobj] or [write to non-copy_on_write area] 78 * I/O takes place directly in object. 79 * 2B: [write to copy_on_write] or [read on NULL uobj] 80 * data is "promoted" from uobj to a new anon. 81 * if uobj is null, then we zero fill. 82 * 83 * we follow the standard UVM locking protocol ordering: 84 * 85 * MAPS => AMAP => UOBJ => ANON => PAGE QUEUES (PQ) 86 * we hold a PG_BUSY page if we unlock for I/O 87 * 88 * 89 * the code is structured as follows: 90 * 91 * - init the "IN" params in the ufi structure 92 * ReFault: (ERESTART returned to the loop in uvm_fault_internal) 93 * - do lookups [locks maps], check protection, handle needs_copy 94 * - check for case 0 fault (error) 95 * - establish "range" of fault 96 * - if we have an amap lock it and extract the anons 97 * - if sequential advice deactivate pages behind us 98 * - at the same time check pmap for unmapped areas and anon for pages 99 * that we could map in (and do map it if found) 100 * - check object for resident pages that we could map in 101 * - if (case 2) goto Case2 102 * - >>> handle case 1 103 * - ensure source anon is resident in RAM 104 * - if case 1B alloc new anon and copy from source 105 * - map the correct page in 106 * Case2: 107 * - >>> handle case 2 108 * - ensure source page is resident (if uobj) 109 * - if case 2B alloc new anon and copy from source (could be zero 110 * fill if uobj == NULL) 111 * - map the correct page in 112 * - done! 113 * 114 * note on paging: 115 * if we have to do I/O we place a PG_BUSY page in the correct object, 116 * unlock everything, and do the I/O. when I/O is done we must reverify 117 * the state of the world before assuming that our data structures are 118 * valid. [because mappings could change while the map is unlocked] 119 * 120 * alternative 1: unbusy the page in question and restart the page fault 121 * from the top (ReFault). this is easy but does not take advantage 122 * of the information that we already have from our previous lookup, 123 * although it is possible that the "hints" in the vm_map will help here. 124 * 125 * alternative 2: the system already keeps track of a "version" number of 126 * a map. [i.e. every time you write-lock a map (e.g. to change a 127 * mapping) you bump the version number up by one...] so, we can save 128 * the version number of the map before we release the lock and start I/O. 129 * then when I/O is done we can relock and check the version numbers 130 * to see if anything changed. this might save us some over 1 because 131 * we don't have to unbusy the page and may be less compares(?). 132 * 133 * alternative 3: put in backpointers or a way to "hold" part of a map 134 * in place while I/O is in progress. this could be complex to 135 * implement (especially with structures like amap that can be referenced 136 * by multiple map entries, and figuring out what should wait could be 137 * complex as well...). 138 * 139 * we use alternative 2. given that we are multi-threaded now we may want 140 * to reconsider the choice. 141 */ 142 143 /* 144 * local data structures 145 */ 146 147 struct uvm_advice { 148 int advice; 149 int nback; 150 int nforw; 151 }; 152 153 /* 154 * page range array: 155 * note: index in array must match "advice" value 156 * XXX: borrowed numbers from freebsd. do they work well for us? 157 */ 158 159 static const struct uvm_advice uvmadvice[] = { 160 { UVM_ADV_NORMAL, 3, 4 }, 161 { UVM_ADV_RANDOM, 0, 0 }, 162 { UVM_ADV_SEQUENTIAL, 8, 7}, 163 }; 164 165 #define UVM_MAXRANGE 16 /* must be MAX() of nback+nforw+1 */ 166 167 /* 168 * private prototypes 169 */ 170 171 /* 172 * externs from other modules 173 */ 174 175 extern int start_init_exec; /* Is init_main() done / init running? */ 176 177 /* 178 * inline functions 179 */ 180 181 /* 182 * uvmfault_anonflush: try and deactivate pages in specified anons 183 * 184 * => does not have to deactivate page if it is busy 185 */ 186 187 static inline void 188 uvmfault_anonflush(struct vm_anon **anons, int n) 189 { 190 int lcv; 191 struct vm_page *pg; 192 193 for (lcv = 0; lcv < n; lcv++) { 194 if (anons[lcv] == NULL) 195 continue; 196 KASSERT(mutex_owned(anons[lcv]->an_lock)); 197 pg = anons[lcv]->an_page; 198 if (pg && (pg->flags & PG_BUSY) == 0) { 199 mutex_enter(&uvm_pageqlock); 200 if (pg->wire_count == 0) { 201 uvm_pagedeactivate(pg); 202 } 203 mutex_exit(&uvm_pageqlock); 204 } 205 } 206 } 207 208 /* 209 * normal functions 210 */ 211 212 /* 213 * uvmfault_amapcopy: clear "needs_copy" in a map. 214 * 215 * => called with VM data structures unlocked (usually, see below) 216 * => we get a write lock on the maps and clear needs_copy for a VA 217 * => if we are out of RAM we sleep (waiting for more) 218 */ 219 220 static void 221 uvmfault_amapcopy(struct uvm_faultinfo *ufi) 222 { 223 for (;;) { 224 225 /* 226 * no mapping? give up. 227 */ 228 229 if (uvmfault_lookup(ufi, true) == false) 230 return; 231 232 /* 233 * copy if needed. 234 */ 235 236 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) 237 amap_copy(ufi->map, ufi->entry, AMAP_COPY_NOWAIT, 238 ufi->orig_rvaddr, ufi->orig_rvaddr + 1); 239 240 /* 241 * didn't work? must be out of RAM. unlock and sleep. 242 */ 243 244 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 245 uvmfault_unlockmaps(ufi, true); 246 uvm_wait("fltamapcopy"); 247 continue; 248 } 249 250 /* 251 * got it! unlock and return. 252 */ 253 254 uvmfault_unlockmaps(ufi, true); 255 return; 256 } 257 /*NOTREACHED*/ 258 } 259 260 /* 261 * uvmfault_anonget: get data in an anon into a non-busy, non-released 262 * page in that anon. 263 * 264 * => Map, amap and thus anon should be locked by caller. 265 * => If we fail, we unlock everything and error is returned. 266 * => If we are successful, return with everything still locked. 267 * => We do not move the page on the queues [gets moved later]. If we 268 * allocate a new page [we_own], it gets put on the queues. Either way, 269 * the result is that the page is on the queues at return time 270 * => For pages which are on loan from a uvm_object (and thus are not owned 271 * by the anon): if successful, return with the owning object locked. 272 * The caller must unlock this object when it unlocks everything else. 273 */ 274 275 int 276 uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap, 277 struct vm_anon *anon) 278 { 279 struct vm_page *pg; 280 int error; 281 282 UVMHIST_FUNC("uvmfault_anonget"); UVMHIST_CALLED(maphist); 283 KASSERT(mutex_owned(anon->an_lock)); 284 KASSERT(anon->an_lock == amap->am_lock); 285 286 /* Increment the counters.*/ 287 uvmexp.fltanget++; 288 if (anon->an_page) { 289 curlwp->l_ru.ru_minflt++; 290 } else { 291 curlwp->l_ru.ru_majflt++; 292 } 293 error = 0; 294 295 /* 296 * Loop until we get the anon data, or fail. 297 */ 298 299 for (;;) { 300 bool we_own, locked; 301 /* 302 * Note: 'we_own' will become true if we set PG_BUSY on a page. 303 */ 304 we_own = false; 305 pg = anon->an_page; 306 307 /* 308 * If there is a resident page and it is loaned, then anon 309 * may not own it. Call out to uvm_anon_lockloanpg() to 310 * identify and lock the real owner of the page. 311 */ 312 313 if (pg && pg->loan_count) 314 pg = uvm_anon_lockloanpg(anon); 315 316 /* 317 * Is page resident? Make sure it is not busy/released. 318 */ 319 320 if (pg) { 321 322 /* 323 * at this point, if the page has a uobject [meaning 324 * we have it on loan], then that uobject is locked 325 * by us! if the page is busy, we drop all the 326 * locks (including uobject) and try again. 327 */ 328 329 if ((pg->flags & PG_BUSY) == 0) { 330 UVMHIST_LOG(maphist, "<- OK",0,0,0,0); 331 return 0; 332 } 333 pg->flags |= PG_WANTED; 334 uvmexp.fltpgwait++; 335 336 /* 337 * The last unlock must be an atomic unlock and wait 338 * on the owner of page. 339 */ 340 341 if (pg->uobject) { 342 /* Owner of page is UVM object. */ 343 uvmfault_unlockall(ufi, amap, NULL); 344 UVMHIST_LOG(maphist, " unlock+wait on uobj",0, 345 0,0,0); 346 UVM_UNLOCK_AND_WAIT(pg, 347 pg->uobject->vmobjlock, 348 false, "anonget1", 0); 349 } else { 350 /* Owner of page is anon. */ 351 uvmfault_unlockall(ufi, NULL, NULL); 352 UVMHIST_LOG(maphist, " unlock+wait on anon",0, 353 0,0,0); 354 UVM_UNLOCK_AND_WAIT(pg, anon->an_lock, 355 false, "anonget2", 0); 356 } 357 } else { 358 #if defined(VMSWAP) 359 /* 360 * No page, therefore allocate one. 361 */ 362 363 pg = uvm_pagealloc(NULL, 364 ufi != NULL ? ufi->orig_rvaddr : 0, 365 anon, ufi != NULL ? UVM_FLAG_COLORMATCH : 0); 366 if (pg == NULL) { 367 /* Out of memory. Wait a little. */ 368 uvmfault_unlockall(ufi, amap, NULL); 369 uvmexp.fltnoram++; 370 UVMHIST_LOG(maphist, " noram -- UVM_WAIT",0, 371 0,0,0); 372 if (!uvm_reclaimable()) { 373 return ENOMEM; 374 } 375 uvm_wait("flt_noram1"); 376 } else { 377 /* PG_BUSY bit is set. */ 378 we_own = true; 379 uvmfault_unlockall(ufi, amap, NULL); 380 381 /* 382 * Pass a PG_BUSY+PG_FAKE+PG_CLEAN page into 383 * the uvm_swap_get() function with all data 384 * structures unlocked. Note that it is OK 385 * to read an_swslot here, because we hold 386 * PG_BUSY on the page. 387 */ 388 uvmexp.pageins++; 389 error = uvm_swap_get(pg, anon->an_swslot, 390 PGO_SYNCIO); 391 392 /* 393 * We clean up after the I/O below in the 394 * 'we_own' case. 395 */ 396 } 397 #else 398 panic("%s: no page", __func__); 399 #endif /* defined(VMSWAP) */ 400 } 401 402 /* 403 * Re-lock the map and anon. 404 */ 405 406 locked = uvmfault_relock(ufi); 407 if (locked || we_own) { 408 mutex_enter(anon->an_lock); 409 } 410 411 /* 412 * If we own the page (i.e. we set PG_BUSY), then we need 413 * to clean up after the I/O. There are three cases to 414 * consider: 415 * 416 * 1) Page was released during I/O: free anon and ReFault. 417 * 2) I/O not OK. Free the page and cause the fault to fail. 418 * 3) I/O OK! Activate the page and sync with the non-we_own 419 * case (i.e. drop anon lock if not locked). 420 */ 421 422 if (we_own) { 423 #if defined(VMSWAP) 424 if (pg->flags & PG_WANTED) { 425 wakeup(pg); 426 } 427 if (error) { 428 429 /* 430 * Remove the swap slot from the anon and 431 * mark the anon as having no real slot. 432 * Do not free the swap slot, thus preventing 433 * it from being used again. 434 */ 435 436 if (anon->an_swslot > 0) { 437 uvm_swap_markbad(anon->an_swslot, 1); 438 } 439 anon->an_swslot = SWSLOT_BAD; 440 441 if ((pg->flags & PG_RELEASED) != 0) { 442 goto released; 443 } 444 445 /* 446 * Note: page was never !PG_BUSY, so it 447 * cannot be mapped and thus no need to 448 * pmap_page_protect() it. 449 */ 450 451 mutex_enter(&uvm_pageqlock); 452 uvm_pagefree(pg); 453 mutex_exit(&uvm_pageqlock); 454 455 if (locked) { 456 uvmfault_unlockall(ufi, NULL, NULL); 457 } 458 mutex_exit(anon->an_lock); 459 UVMHIST_LOG(maphist, "<- ERROR", 0,0,0,0); 460 return error; 461 } 462 463 if ((pg->flags & PG_RELEASED) != 0) { 464 released: 465 KASSERT(anon->an_ref == 0); 466 467 /* 468 * Released while we had unlocked amap. 469 */ 470 471 if (locked) { 472 uvmfault_unlockall(ufi, NULL, NULL); 473 } 474 uvm_anon_release(anon); 475 476 if (error) { 477 UVMHIST_LOG(maphist, 478 "<- ERROR/RELEASED", 0,0,0,0); 479 return error; 480 } 481 482 UVMHIST_LOG(maphist, "<- RELEASED", 0,0,0,0); 483 return ERESTART; 484 } 485 486 /* 487 * We have successfully read the page, activate it. 488 */ 489 490 mutex_enter(&uvm_pageqlock); 491 uvm_pageactivate(pg); 492 mutex_exit(&uvm_pageqlock); 493 pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE); 494 UVM_PAGE_OWN(pg, NULL); 495 #else 496 panic("%s: we_own", __func__); 497 #endif /* defined(VMSWAP) */ 498 } 499 500 /* 501 * We were not able to re-lock the map - restart the fault. 502 */ 503 504 if (!locked) { 505 if (we_own) { 506 mutex_exit(anon->an_lock); 507 } 508 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 509 return ERESTART; 510 } 511 512 /* 513 * Verify that no one has touched the amap and moved 514 * the anon on us. 515 */ 516 517 if (ufi != NULL && amap_lookup(&ufi->entry->aref, 518 ufi->orig_rvaddr - ufi->entry->start) != anon) { 519 520 uvmfault_unlockall(ufi, amap, NULL); 521 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 522 return ERESTART; 523 } 524 525 /* 526 * Retry.. 527 */ 528 529 uvmexp.fltanretry++; 530 continue; 531 } 532 /*NOTREACHED*/ 533 } 534 535 /* 536 * uvmfault_promote: promote data to a new anon. used for 1B and 2B. 537 * 538 * 1. allocate an anon and a page. 539 * 2. fill its contents. 540 * 3. put it into amap. 541 * 542 * => if we fail (result != 0) we unlock everything. 543 * => on success, return a new locked anon via 'nanon'. 544 * (*nanon)->an_page will be a resident, locked, dirty page. 545 * => it's caller's responsibility to put the promoted nanon->an_page to the 546 * page queue. 547 */ 548 549 static int 550 uvmfault_promote(struct uvm_faultinfo *ufi, 551 struct vm_anon *oanon, 552 struct vm_page *uobjpage, 553 struct vm_anon **nanon, /* OUT: allocated anon */ 554 struct vm_anon **spare) 555 { 556 struct vm_amap *amap = ufi->entry->aref.ar_amap; 557 struct uvm_object *uobj; 558 struct vm_anon *anon; 559 struct vm_page *pg; 560 struct vm_page *opg; 561 int error; 562 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 563 564 if (oanon) { 565 /* anon COW */ 566 opg = oanon->an_page; 567 KASSERT(opg != NULL); 568 KASSERT(opg->uobject == NULL || opg->loan_count > 0); 569 } else if (uobjpage != PGO_DONTCARE) { 570 /* object-backed COW */ 571 opg = uobjpage; 572 } else { 573 /* ZFOD */ 574 opg = NULL; 575 } 576 if (opg != NULL) { 577 uobj = opg->uobject; 578 } else { 579 uobj = NULL; 580 } 581 582 KASSERT(amap != NULL); 583 KASSERT(uobjpage != NULL); 584 KASSERT(uobjpage == PGO_DONTCARE || (uobjpage->flags & PG_BUSY) != 0); 585 KASSERT(mutex_owned(amap->am_lock)); 586 KASSERT(oanon == NULL || amap->am_lock == oanon->an_lock); 587 KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); 588 589 if (*spare != NULL) { 590 anon = *spare; 591 *spare = NULL; 592 } else { 593 anon = uvm_analloc(); 594 } 595 if (anon) { 596 597 /* 598 * The new anon is locked. 599 * 600 * if opg == NULL, we want a zero'd, dirty page, 601 * so have uvm_pagealloc() do that for us. 602 */ 603 604 KASSERT(anon->an_lock == NULL); 605 anon->an_lock = amap->am_lock; 606 pg = uvm_pagealloc(NULL, ufi->orig_rvaddr, anon, 607 UVM_FLAG_COLORMATCH | (opg == NULL ? UVM_PGA_ZERO : 0)); 608 if (pg == NULL) { 609 anon->an_lock = NULL; 610 } 611 } else { 612 pg = NULL; 613 } 614 615 /* 616 * out of memory resources? 617 */ 618 619 if (pg == NULL) { 620 /* save anon for the next try. */ 621 if (anon != NULL) { 622 *spare = anon; 623 } 624 625 /* unlock and fail ... */ 626 uvm_page_unbusy(&uobjpage, 1); 627 uvmfault_unlockall(ufi, amap, uobj); 628 if (!uvm_reclaimable()) { 629 UVMHIST_LOG(maphist, "out of VM", 0,0,0,0); 630 uvmexp.fltnoanon++; 631 error = ENOMEM; 632 goto done; 633 } 634 635 UVMHIST_LOG(maphist, "out of RAM, waiting for more", 0,0,0,0); 636 uvmexp.fltnoram++; 637 uvm_wait("flt_noram5"); 638 error = ERESTART; 639 goto done; 640 } 641 642 /* copy page [pg now dirty] */ 643 if (opg) { 644 uvm_pagecopy(opg, pg); 645 } 646 647 amap_add(&ufi->entry->aref, ufi->orig_rvaddr - ufi->entry->start, anon, 648 oanon != NULL); 649 650 *nanon = anon; 651 error = 0; 652 done: 653 return error; 654 } 655 656 657 /* 658 * F A U L T - m a i n e n t r y p o i n t 659 */ 660 661 /* 662 * uvm_fault: page fault handler 663 * 664 * => called from MD code to resolve a page fault 665 * => VM data structures usually should be unlocked. however, it is 666 * possible to call here with the main map locked if the caller 667 * gets a write lock, sets it recusive, and then calls us (c.f. 668 * uvm_map_pageable). this should be avoided because it keeps 669 * the map locked off during I/O. 670 * => MUST NEVER BE CALLED IN INTERRUPT CONTEXT 671 */ 672 673 #define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \ 674 ~VM_PROT_WRITE : VM_PROT_ALL) 675 676 /* fault_flag values passed from uvm_fault_wire to uvm_fault_internal */ 677 #define UVM_FAULT_WIRE (1 << 0) 678 #define UVM_FAULT_MAXPROT (1 << 1) 679 680 struct uvm_faultctx { 681 682 /* 683 * the following members are set up by uvm_fault_check() and 684 * read-only after that. 685 * 686 * note that narrow is used by uvm_fault_check() to change 687 * the behaviour after ERESTART. 688 * 689 * most of them might change after RESTART if the underlying 690 * map entry has been changed behind us. an exception is 691 * wire_paging, which does never change. 692 */ 693 vm_prot_t access_type; 694 vaddr_t startva; 695 int npages; 696 int centeridx; 697 bool narrow; /* work on a single requested page only */ 698 bool wire_mapping; /* request a PMAP_WIRED mapping 699 (UVM_FAULT_WIRE or VM_MAPENT_ISWIRED) */ 700 bool wire_paging; /* request uvm_pagewire 701 (true for UVM_FAULT_WIRE) */ 702 bool cow_now; /* VM_PROT_WRITE is actually requested 703 (ie. should break COW and page loaning) */ 704 705 /* 706 * enter_prot is set up by uvm_fault_check() and clamped 707 * (ie. drop the VM_PROT_WRITE bit) in various places in case 708 * of !cow_now. 709 */ 710 vm_prot_t enter_prot; /* prot at which we want to enter pages in */ 711 712 /* 713 * the following member is for uvmfault_promote() and ERESTART. 714 */ 715 struct vm_anon *anon_spare; 716 717 /* 718 * the folloing is actually a uvm_fault_lower() internal. 719 * it's here merely for debugging. 720 * (or due to the mechanical separation of the function?) 721 */ 722 bool promote; 723 }; 724 725 static inline int uvm_fault_check( 726 struct uvm_faultinfo *, struct uvm_faultctx *, 727 struct vm_anon ***, bool); 728 729 static int uvm_fault_upper( 730 struct uvm_faultinfo *, struct uvm_faultctx *, 731 struct vm_anon **); 732 static inline int uvm_fault_upper_lookup( 733 struct uvm_faultinfo *, const struct uvm_faultctx *, 734 struct vm_anon **, struct vm_page **); 735 static inline void uvm_fault_upper_neighbor( 736 struct uvm_faultinfo *, const struct uvm_faultctx *, 737 vaddr_t, struct vm_page *, bool); 738 static inline int uvm_fault_upper_loan( 739 struct uvm_faultinfo *, struct uvm_faultctx *, 740 struct vm_anon *, struct uvm_object **); 741 static inline int uvm_fault_upper_promote( 742 struct uvm_faultinfo *, struct uvm_faultctx *, 743 struct uvm_object *, struct vm_anon *); 744 static inline int uvm_fault_upper_direct( 745 struct uvm_faultinfo *, struct uvm_faultctx *, 746 struct uvm_object *, struct vm_anon *); 747 static int uvm_fault_upper_enter( 748 struct uvm_faultinfo *, const struct uvm_faultctx *, 749 struct uvm_object *, struct vm_anon *, 750 struct vm_page *, struct vm_anon *); 751 static inline void uvm_fault_upper_done( 752 struct uvm_faultinfo *, const struct uvm_faultctx *, 753 struct vm_anon *, struct vm_page *); 754 755 static int uvm_fault_lower( 756 struct uvm_faultinfo *, struct uvm_faultctx *, 757 struct vm_page **); 758 static inline void uvm_fault_lower_lookup( 759 struct uvm_faultinfo *, const struct uvm_faultctx *, 760 struct vm_page **); 761 static inline void uvm_fault_lower_neighbor( 762 struct uvm_faultinfo *, const struct uvm_faultctx *, 763 vaddr_t, struct vm_page *, bool); 764 static inline int uvm_fault_lower_io( 765 struct uvm_faultinfo *, const struct uvm_faultctx *, 766 struct uvm_object **, struct vm_page **); 767 static inline int uvm_fault_lower_direct( 768 struct uvm_faultinfo *, struct uvm_faultctx *, 769 struct uvm_object *, struct vm_page *); 770 static inline int uvm_fault_lower_direct_loan( 771 struct uvm_faultinfo *, struct uvm_faultctx *, 772 struct uvm_object *, struct vm_page **, 773 struct vm_page **); 774 static inline int uvm_fault_lower_promote( 775 struct uvm_faultinfo *, struct uvm_faultctx *, 776 struct uvm_object *, struct vm_page *); 777 static int uvm_fault_lower_enter( 778 struct uvm_faultinfo *, const struct uvm_faultctx *, 779 struct uvm_object *, 780 struct vm_anon *, struct vm_page *); 781 static inline void uvm_fault_lower_done( 782 struct uvm_faultinfo *, const struct uvm_faultctx *, 783 struct uvm_object *, struct vm_page *); 784 785 int 786 uvm_fault_internal(struct vm_map *orig_map, vaddr_t vaddr, 787 vm_prot_t access_type, int fault_flag) 788 { 789 struct cpu_data *cd; 790 struct uvm_cpu *ucpu; 791 struct uvm_faultinfo ufi; 792 struct uvm_faultctx flt = { 793 .access_type = access_type, 794 795 /* don't look for neighborhood * pages on "wire" fault */ 796 .narrow = (fault_flag & UVM_FAULT_WIRE) != 0, 797 798 /* "wire" fault causes wiring of both mapping and paging */ 799 .wire_mapping = (fault_flag & UVM_FAULT_WIRE) != 0, 800 .wire_paging = (fault_flag & UVM_FAULT_WIRE) != 0, 801 }; 802 const bool maxprot = (fault_flag & UVM_FAULT_MAXPROT) != 0; 803 struct vm_anon *anons_store[UVM_MAXRANGE], **anons; 804 struct vm_page *pages_store[UVM_MAXRANGE], **pages; 805 int error; 806 #if 0 807 uintptr_t delta, delta2, delta3; 808 #endif 809 UVMHIST_FUNC("uvm_fault"); UVMHIST_CALLED(maphist); 810 811 UVMHIST_LOG(maphist, "(map=0x%x, vaddr=0x%x, at=%d, ff=%d)", 812 orig_map, vaddr, access_type, fault_flag); 813 814 cd = &(curcpu()->ci_data); 815 cd->cpu_nfault++; 816 ucpu = cd->cpu_uvm; 817 818 /* Don't flood RNG subsystem with samples. */ 819 if (cd->cpu_nfault % 503) 820 goto norng; 821 #if 0 822 /* 823 * Avoid trying to count "entropy" for accesses of regular 824 * stride, by checking the 1st, 2nd, 3rd order differentials 825 * of vaddr, like the rnd code does internally with sample times. 826 * 827 * XXX If the selection of only every 503rd fault above is 828 * XXX removed, this code should exclude most samples, but 829 * XXX does not, and is therefore disabled. 830 */ 831 if (ucpu->last_fltaddr > (uintptr_t)trunc_page(vaddr)) 832 delta = ucpu->last_fltaddr - (uintptr_t)trunc_page(vaddr); 833 else 834 delta = (uintptr_t)trunc_page(vaddr) - ucpu->last_fltaddr; 835 836 if (ucpu->last_delta > delta) 837 delta2 = ucpu->last_delta - delta; 838 else 839 delta2 = delta - ucpu->last_delta; 840 841 if (ucpu->last_delta2 > delta2) 842 delta3 = ucpu->last_delta2 - delta2; 843 else 844 delta3 = delta2 - ucpu->last_delta2; 845 846 ucpu->last_fltaddr = (uintptr_t)vaddr; 847 ucpu->last_delta = delta; 848 ucpu->last_delta2 = delta2; 849 850 if (delta != 0 && delta2 != 0 && delta3 != 0) 851 #endif 852 /* Don't count anything until user interaction is possible */ 853 if (__predict_true(start_init_exec)) { 854 kpreempt_disable(); 855 rnd_add_uint32(&ucpu->rs, 856 sizeof(vaddr_t) == sizeof(uint32_t) ? 857 (uint32_t)vaddr : sizeof(vaddr_t) == 858 sizeof(uint64_t) ? 859 (uint32_t)(vaddr & 0x00000000ffffffff) : 860 (uint32_t)(cd->cpu_nfault & 0x00000000ffffffff)); 861 kpreempt_enable(); 862 } 863 norng: 864 /* 865 * init the IN parameters in the ufi 866 */ 867 868 ufi.orig_map = orig_map; 869 ufi.orig_rvaddr = trunc_page(vaddr); 870 ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */ 871 872 error = ERESTART; 873 while (error == ERESTART) { /* ReFault: */ 874 anons = anons_store; 875 pages = pages_store; 876 877 error = uvm_fault_check(&ufi, &flt, &anons, maxprot); 878 if (error != 0) 879 continue; 880 881 error = uvm_fault_upper_lookup(&ufi, &flt, anons, pages); 882 if (error != 0) 883 continue; 884 885 if (pages[flt.centeridx] == PGO_DONTCARE) 886 error = uvm_fault_upper(&ufi, &flt, anons); 887 else { 888 struct uvm_object * const uobj = 889 ufi.entry->object.uvm_obj; 890 891 if (uobj && uobj->pgops->pgo_fault != NULL) { 892 /* 893 * invoke "special" fault routine. 894 */ 895 mutex_enter(uobj->vmobjlock); 896 /* locked: maps(read), amap(if there), uobj */ 897 error = uobj->pgops->pgo_fault(&ufi, 898 flt.startva, pages, flt.npages, 899 flt.centeridx, flt.access_type, 900 PGO_LOCKED|PGO_SYNCIO); 901 902 /* 903 * locked: nothing, pgo_fault has unlocked 904 * everything 905 */ 906 907 /* 908 * object fault routine responsible for 909 * pmap_update(). 910 */ 911 } else { 912 error = uvm_fault_lower(&ufi, &flt, pages); 913 } 914 } 915 } 916 917 if (flt.anon_spare != NULL) { 918 flt.anon_spare->an_ref--; 919 KASSERT(flt.anon_spare->an_ref == 0); 920 KASSERT(flt.anon_spare->an_lock == NULL); 921 uvm_anon_free(flt.anon_spare); 922 } 923 return error; 924 } 925 926 /* 927 * uvm_fault_check: check prot, handle needs-copy, etc. 928 * 929 * 1. lookup entry. 930 * 2. check protection. 931 * 3. adjust fault condition (mainly for simulated fault). 932 * 4. handle needs-copy (lazy amap copy). 933 * 5. establish range of interest for neighbor fault (aka pre-fault). 934 * 6. look up anons (if amap exists). 935 * 7. flush pages (if MADV_SEQUENTIAL) 936 * 937 * => called with nothing locked. 938 * => if we fail (result != 0) we unlock everything. 939 * => initialize/adjust many members of flt. 940 */ 941 942 static int 943 uvm_fault_check( 944 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 945 struct vm_anon ***ranons, bool maxprot) 946 { 947 struct vm_amap *amap; 948 struct uvm_object *uobj; 949 vm_prot_t check_prot; 950 int nback, nforw; 951 UVMHIST_FUNC("uvm_fault_check"); UVMHIST_CALLED(maphist); 952 953 /* 954 * lookup and lock the maps 955 */ 956 957 if (uvmfault_lookup(ufi, false) == false) { 958 UVMHIST_LOG(maphist, "<- no mapping @ 0x%x", ufi->orig_rvaddr, 959 0,0,0); 960 return EFAULT; 961 } 962 /* locked: maps(read) */ 963 964 #ifdef DIAGNOSTIC 965 if ((ufi->map->flags & VM_MAP_PAGEABLE) == 0) { 966 printf("Page fault on non-pageable map:\n"); 967 printf("ufi->map = %p\n", ufi->map); 968 printf("ufi->orig_map = %p\n", ufi->orig_map); 969 printf("ufi->orig_rvaddr = 0x%lx\n", (u_long) ufi->orig_rvaddr); 970 panic("uvm_fault: (ufi->map->flags & VM_MAP_PAGEABLE) == 0"); 971 } 972 #endif 973 974 /* 975 * check protection 976 */ 977 978 check_prot = maxprot ? 979 ufi->entry->max_protection : ufi->entry->protection; 980 if ((check_prot & flt->access_type) != flt->access_type) { 981 UVMHIST_LOG(maphist, 982 "<- protection failure (prot=0x%x, access=0x%x)", 983 ufi->entry->protection, flt->access_type, 0, 0); 984 uvmfault_unlockmaps(ufi, false); 985 return EACCES; 986 } 987 988 /* 989 * "enter_prot" is the protection we want to enter the page in at. 990 * for certain pages (e.g. copy-on-write pages) this protection can 991 * be more strict than ufi->entry->protection. "wired" means either 992 * the entry is wired or we are fault-wiring the pg. 993 */ 994 995 flt->enter_prot = ufi->entry->protection; 996 if (VM_MAPENT_ISWIRED(ufi->entry)) 997 flt->wire_mapping = true; 998 999 if (flt->wire_mapping) { 1000 flt->access_type = flt->enter_prot; /* full access for wired */ 1001 flt->cow_now = (check_prot & VM_PROT_WRITE) != 0; 1002 } else { 1003 flt->cow_now = (flt->access_type & VM_PROT_WRITE) != 0; 1004 } 1005 1006 flt->promote = false; 1007 1008 /* 1009 * handle "needs_copy" case. if we need to copy the amap we will 1010 * have to drop our readlock and relock it with a write lock. (we 1011 * need a write lock to change anything in a map entry [e.g. 1012 * needs_copy]). 1013 */ 1014 1015 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 1016 if (flt->cow_now || (ufi->entry->object.uvm_obj == NULL)) { 1017 KASSERT(!maxprot); 1018 /* need to clear */ 1019 UVMHIST_LOG(maphist, 1020 " need to clear needs_copy and refault",0,0,0,0); 1021 uvmfault_unlockmaps(ufi, false); 1022 uvmfault_amapcopy(ufi); 1023 uvmexp.fltamcopy++; 1024 return ERESTART; 1025 1026 } else { 1027 1028 /* 1029 * ensure that we pmap_enter page R/O since 1030 * needs_copy is still true 1031 */ 1032 1033 flt->enter_prot &= ~VM_PROT_WRITE; 1034 } 1035 } 1036 1037 /* 1038 * identify the players 1039 */ 1040 1041 amap = ufi->entry->aref.ar_amap; /* upper layer */ 1042 uobj = ufi->entry->object.uvm_obj; /* lower layer */ 1043 1044 /* 1045 * check for a case 0 fault. if nothing backing the entry then 1046 * error now. 1047 */ 1048 1049 if (amap == NULL && uobj == NULL) { 1050 uvmfault_unlockmaps(ufi, false); 1051 UVMHIST_LOG(maphist,"<- no backing store, no overlay",0,0,0,0); 1052 return EFAULT; 1053 } 1054 1055 /* 1056 * establish range of interest based on advice from mapper 1057 * and then clip to fit map entry. note that we only want 1058 * to do this the first time through the fault. if we 1059 * ReFault we will disable this by setting "narrow" to true. 1060 */ 1061 1062 if (flt->narrow == false) { 1063 1064 /* wide fault (!narrow) */ 1065 KASSERT(uvmadvice[ufi->entry->advice].advice == 1066 ufi->entry->advice); 1067 nback = MIN(uvmadvice[ufi->entry->advice].nback, 1068 (ufi->orig_rvaddr - ufi->entry->start) >> PAGE_SHIFT); 1069 flt->startva = ufi->orig_rvaddr - (nback << PAGE_SHIFT); 1070 /* 1071 * note: "-1" because we don't want to count the 1072 * faulting page as forw 1073 */ 1074 nforw = MIN(uvmadvice[ufi->entry->advice].nforw, 1075 ((ufi->entry->end - ufi->orig_rvaddr) >> 1076 PAGE_SHIFT) - 1); 1077 flt->npages = nback + nforw + 1; 1078 flt->centeridx = nback; 1079 1080 flt->narrow = true; /* ensure only once per-fault */ 1081 1082 } else { 1083 1084 /* narrow fault! */ 1085 nback = nforw = 0; 1086 flt->startva = ufi->orig_rvaddr; 1087 flt->npages = 1; 1088 flt->centeridx = 0; 1089 1090 } 1091 /* offset from entry's start to pgs' start */ 1092 const voff_t eoff = flt->startva - ufi->entry->start; 1093 1094 /* locked: maps(read) */ 1095 UVMHIST_LOG(maphist, " narrow=%d, back=%d, forw=%d, startva=0x%x", 1096 flt->narrow, nback, nforw, flt->startva); 1097 UVMHIST_LOG(maphist, " entry=0x%x, amap=0x%x, obj=0x%x", ufi->entry, 1098 amap, uobj, 0); 1099 1100 /* 1101 * if we've got an amap, lock it and extract current anons. 1102 */ 1103 1104 if (amap) { 1105 amap_lock(amap); 1106 amap_lookups(&ufi->entry->aref, eoff, *ranons, flt->npages); 1107 } else { 1108 *ranons = NULL; /* to be safe */ 1109 } 1110 1111 /* locked: maps(read), amap(if there) */ 1112 KASSERT(amap == NULL || mutex_owned(amap->am_lock)); 1113 1114 /* 1115 * for MADV_SEQUENTIAL mappings we want to deactivate the back pages 1116 * now and then forget about them (for the rest of the fault). 1117 */ 1118 1119 if (ufi->entry->advice == MADV_SEQUENTIAL && nback != 0) { 1120 1121 UVMHIST_LOG(maphist, " MADV_SEQUENTIAL: flushing backpages", 1122 0,0,0,0); 1123 /* flush back-page anons? */ 1124 if (amap) 1125 uvmfault_anonflush(*ranons, nback); 1126 1127 /* flush object? */ 1128 if (uobj) { 1129 voff_t uoff; 1130 1131 uoff = ufi->entry->offset + eoff; 1132 mutex_enter(uobj->vmobjlock); 1133 (void) (uobj->pgops->pgo_put)(uobj, uoff, uoff + 1134 (nback << PAGE_SHIFT), PGO_DEACTIVATE); 1135 } 1136 1137 /* now forget about the backpages */ 1138 if (amap) 1139 *ranons += nback; 1140 flt->startva += (nback << PAGE_SHIFT); 1141 flt->npages -= nback; 1142 flt->centeridx = 0; 1143 } 1144 /* 1145 * => startva is fixed 1146 * => npages is fixed 1147 */ 1148 KASSERT(flt->startva <= ufi->orig_rvaddr); 1149 KASSERT(ufi->orig_rvaddr + ufi->orig_size <= 1150 flt->startva + (flt->npages << PAGE_SHIFT)); 1151 return 0; 1152 } 1153 1154 /* 1155 * uvm_fault_upper_lookup: look up existing h/w mapping and amap. 1156 * 1157 * iterate range of interest: 1158 * 1. check if h/w mapping exists. if yes, we don't care 1159 * 2. check if anon exists. if not, page is lower. 1160 * 3. if anon exists, enter h/w mapping for neighbors. 1161 * 1162 * => called with amap locked (if exists). 1163 */ 1164 1165 static int 1166 uvm_fault_upper_lookup( 1167 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1168 struct vm_anon **anons, struct vm_page **pages) 1169 { 1170 struct vm_amap *amap = ufi->entry->aref.ar_amap; 1171 int lcv; 1172 vaddr_t currva; 1173 bool shadowed; 1174 UVMHIST_FUNC("uvm_fault_upper_lookup"); UVMHIST_CALLED(maphist); 1175 1176 /* locked: maps(read), amap(if there) */ 1177 KASSERT(amap == NULL || mutex_owned(amap->am_lock)); 1178 1179 /* 1180 * map in the backpages and frontpages we found in the amap in hopes 1181 * of preventing future faults. we also init the pages[] array as 1182 * we go. 1183 */ 1184 1185 currva = flt->startva; 1186 shadowed = false; 1187 for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { 1188 /* 1189 * don't play with VAs that are already mapped 1190 * (except for center) 1191 */ 1192 if (lcv != flt->centeridx && 1193 pmap_extract(ufi->orig_map->pmap, currva, NULL)) { 1194 pages[lcv] = PGO_DONTCARE; 1195 continue; 1196 } 1197 1198 /* 1199 * unmapped or center page. check if any anon at this level. 1200 */ 1201 if (amap == NULL || anons[lcv] == NULL) { 1202 pages[lcv] = NULL; 1203 continue; 1204 } 1205 1206 /* 1207 * check for present page and map if possible. re-activate it. 1208 */ 1209 1210 pages[lcv] = PGO_DONTCARE; 1211 if (lcv == flt->centeridx) { /* save center for later! */ 1212 shadowed = true; 1213 continue; 1214 } 1215 1216 struct vm_anon *anon = anons[lcv]; 1217 struct vm_page *pg = anon->an_page; 1218 1219 KASSERT(anon->an_lock == amap->am_lock); 1220 1221 /* Ignore loaned and busy pages. */ 1222 if (pg && pg->loan_count == 0 && (pg->flags & PG_BUSY) == 0) { 1223 uvm_fault_upper_neighbor(ufi, flt, currva, 1224 pg, anon->an_ref > 1); 1225 } 1226 } 1227 1228 /* locked: maps(read), amap(if there) */ 1229 KASSERT(amap == NULL || mutex_owned(amap->am_lock)); 1230 /* (shadowed == true) if there is an anon at the faulting address */ 1231 UVMHIST_LOG(maphist, " shadowed=%d, will_get=%d", shadowed, 1232 (ufi->entry->object.uvm_obj && shadowed != false),0,0); 1233 1234 /* 1235 * note that if we are really short of RAM we could sleep in the above 1236 * call to pmap_enter with everything locked. bad? 1237 * 1238 * XXX Actually, that is bad; pmap_enter() should just fail in that 1239 * XXX case. --thorpej 1240 */ 1241 1242 return 0; 1243 } 1244 1245 /* 1246 * uvm_fault_upper_neighbor: enter single lower neighbor page. 1247 * 1248 * => called with amap and anon locked. 1249 */ 1250 1251 static void 1252 uvm_fault_upper_neighbor( 1253 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1254 vaddr_t currva, struct vm_page *pg, bool readonly) 1255 { 1256 UVMHIST_FUNC("uvm_fault_upper_neighbor"); UVMHIST_CALLED(maphist); 1257 1258 /* locked: amap, anon */ 1259 1260 mutex_enter(&uvm_pageqlock); 1261 uvm_pageenqueue(pg); 1262 mutex_exit(&uvm_pageqlock); 1263 UVMHIST_LOG(maphist, 1264 " MAPPING: n anon: pm=0x%x, va=0x%x, pg=0x%x", 1265 ufi->orig_map->pmap, currva, pg, 0); 1266 uvmexp.fltnamap++; 1267 1268 /* 1269 * Since this page isn't the page that's actually faulting, 1270 * ignore pmap_enter() failures; it's not critical that we 1271 * enter these right now. 1272 */ 1273 1274 (void) pmap_enter(ufi->orig_map->pmap, currva, 1275 VM_PAGE_TO_PHYS(pg), 1276 readonly ? (flt->enter_prot & ~VM_PROT_WRITE) : 1277 flt->enter_prot, 1278 PMAP_CANFAIL | (flt->wire_mapping ? PMAP_WIRED : 0)); 1279 1280 pmap_update(ufi->orig_map->pmap); 1281 } 1282 1283 /* 1284 * uvm_fault_upper: handle upper fault. 1285 * 1286 * 1. acquire anon lock. 1287 * 2. get anon. let uvmfault_anonget do the dirty work. 1288 * 3. handle loan. 1289 * 4. dispatch direct or promote handlers. 1290 */ 1291 1292 static int 1293 uvm_fault_upper( 1294 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1295 struct vm_anon **anons) 1296 { 1297 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1298 struct vm_anon * const anon = anons[flt->centeridx]; 1299 struct uvm_object *uobj; 1300 int error; 1301 UVMHIST_FUNC("uvm_fault_upper"); UVMHIST_CALLED(maphist); 1302 1303 /* locked: maps(read), amap, anon */ 1304 KASSERT(mutex_owned(amap->am_lock)); 1305 KASSERT(anon->an_lock == amap->am_lock); 1306 1307 /* 1308 * handle case 1: fault on an anon in our amap 1309 */ 1310 1311 UVMHIST_LOG(maphist, " case 1 fault: anon=0x%x", anon, 0,0,0); 1312 1313 /* 1314 * no matter if we have case 1A or case 1B we are going to need to 1315 * have the anon's memory resident. ensure that now. 1316 */ 1317 1318 /* 1319 * let uvmfault_anonget do the dirty work. 1320 * if it fails (!OK) it will unlock everything for us. 1321 * if it succeeds, locks are still valid and locked. 1322 * also, if it is OK, then the anon's page is on the queues. 1323 * if the page is on loan from a uvm_object, then anonget will 1324 * lock that object for us if it does not fail. 1325 */ 1326 1327 error = uvmfault_anonget(ufi, amap, anon); 1328 switch (error) { 1329 case 0: 1330 break; 1331 1332 case ERESTART: 1333 return ERESTART; 1334 1335 case EAGAIN: 1336 kpause("fltagain1", false, hz/2, NULL); 1337 return ERESTART; 1338 1339 default: 1340 return error; 1341 } 1342 1343 /* 1344 * uobj is non null if the page is on loan from an object (i.e. uobj) 1345 */ 1346 1347 uobj = anon->an_page->uobject; /* locked by anonget if !NULL */ 1348 1349 /* locked: maps(read), amap, anon, uobj(if one) */ 1350 KASSERT(mutex_owned(amap->am_lock)); 1351 KASSERT(anon->an_lock == amap->am_lock); 1352 KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); 1353 1354 /* 1355 * special handling for loaned pages 1356 */ 1357 1358 if (anon->an_page->loan_count) { 1359 error = uvm_fault_upper_loan(ufi, flt, anon, &uobj); 1360 if (error != 0) 1361 return error; 1362 } 1363 1364 /* 1365 * if we are case 1B then we will need to allocate a new blank 1366 * anon to transfer the data into. note that we have a lock 1367 * on anon, so no one can busy or release the page until we are done. 1368 * also note that the ref count can't drop to zero here because 1369 * it is > 1 and we are only dropping one ref. 1370 * 1371 * in the (hopefully very rare) case that we are out of RAM we 1372 * will unlock, wait for more RAM, and refault. 1373 * 1374 * if we are out of anon VM we kill the process (XXX: could wait?). 1375 */ 1376 1377 if (flt->cow_now && anon->an_ref > 1) { 1378 flt->promote = true; 1379 error = uvm_fault_upper_promote(ufi, flt, uobj, anon); 1380 } else { 1381 error = uvm_fault_upper_direct(ufi, flt, uobj, anon); 1382 } 1383 return error; 1384 } 1385 1386 /* 1387 * uvm_fault_upper_loan: handle loaned upper page. 1388 * 1389 * 1. if not cow'ing now, simply adjust flt->enter_prot. 1390 * 2. if cow'ing now, and if ref count is 1, break loan. 1391 */ 1392 1393 static int 1394 uvm_fault_upper_loan( 1395 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1396 struct vm_anon *anon, struct uvm_object **ruobj) 1397 { 1398 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1399 int error = 0; 1400 UVMHIST_FUNC("uvm_fault_upper_loan"); UVMHIST_CALLED(maphist); 1401 1402 if (!flt->cow_now) { 1403 1404 /* 1405 * for read faults on loaned pages we just cap the 1406 * protection at read-only. 1407 */ 1408 1409 flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; 1410 1411 } else { 1412 /* 1413 * note that we can't allow writes into a loaned page! 1414 * 1415 * if we have a write fault on a loaned page in an 1416 * anon then we need to look at the anon's ref count. 1417 * if it is greater than one then we are going to do 1418 * a normal copy-on-write fault into a new anon (this 1419 * is not a problem). however, if the reference count 1420 * is one (a case where we would normally allow a 1421 * write directly to the page) then we need to kill 1422 * the loan before we continue. 1423 */ 1424 1425 /* >1 case is already ok */ 1426 if (anon->an_ref == 1) { 1427 error = uvm_loanbreak_anon(anon, *ruobj); 1428 if (error != 0) { 1429 uvmfault_unlockall(ufi, amap, *ruobj); 1430 uvm_wait("flt_noram2"); 1431 return ERESTART; 1432 } 1433 /* if we were a loan reciever uobj is gone */ 1434 if (*ruobj) 1435 *ruobj = NULL; 1436 } 1437 } 1438 return error; 1439 } 1440 1441 /* 1442 * uvm_fault_upper_promote: promote upper page. 1443 * 1444 * 1. call uvmfault_promote. 1445 * 2. enqueue page. 1446 * 3. deref. 1447 * 4. pass page to uvm_fault_upper_enter. 1448 */ 1449 1450 static int 1451 uvm_fault_upper_promote( 1452 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1453 struct uvm_object *uobj, struct vm_anon *anon) 1454 { 1455 struct vm_anon * const oanon = anon; 1456 struct vm_page *pg; 1457 int error; 1458 UVMHIST_FUNC("uvm_fault_upper_promote"); UVMHIST_CALLED(maphist); 1459 1460 UVMHIST_LOG(maphist, " case 1B: COW fault",0,0,0,0); 1461 uvmexp.flt_acow++; 1462 1463 error = uvmfault_promote(ufi, oanon, PGO_DONTCARE, &anon, 1464 &flt->anon_spare); 1465 switch (error) { 1466 case 0: 1467 break; 1468 case ERESTART: 1469 return ERESTART; 1470 default: 1471 return error; 1472 } 1473 1474 KASSERT(anon == NULL || anon->an_lock == oanon->an_lock); 1475 1476 pg = anon->an_page; 1477 mutex_enter(&uvm_pageqlock); 1478 uvm_pageenqueue(pg); /* uvm_fault_upper_done will activate the page */ 1479 mutex_exit(&uvm_pageqlock); 1480 pg->flags &= ~(PG_BUSY|PG_FAKE); 1481 UVM_PAGE_OWN(pg, NULL); 1482 1483 /* deref: can not drop to zero here by defn! */ 1484 KASSERT(oanon->an_ref > 1); 1485 oanon->an_ref--; 1486 1487 /* 1488 * note: oanon is still locked, as is the new anon. we 1489 * need to check for this later when we unlock oanon; if 1490 * oanon != anon, we'll have to unlock anon, too. 1491 */ 1492 1493 return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon); 1494 } 1495 1496 /* 1497 * uvm_fault_upper_direct: handle direct fault. 1498 */ 1499 1500 static int 1501 uvm_fault_upper_direct( 1502 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1503 struct uvm_object *uobj, struct vm_anon *anon) 1504 { 1505 struct vm_anon * const oanon = anon; 1506 struct vm_page *pg; 1507 UVMHIST_FUNC("uvm_fault_upper_direct"); UVMHIST_CALLED(maphist); 1508 1509 uvmexp.flt_anon++; 1510 pg = anon->an_page; 1511 if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */ 1512 flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; 1513 1514 return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon); 1515 } 1516 1517 /* 1518 * uvm_fault_upper_enter: enter h/w mapping of upper page. 1519 */ 1520 1521 static int 1522 uvm_fault_upper_enter( 1523 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1524 struct uvm_object *uobj, struct vm_anon *anon, struct vm_page *pg, 1525 struct vm_anon *oanon) 1526 { 1527 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1528 UVMHIST_FUNC("uvm_fault_upper_enter"); UVMHIST_CALLED(maphist); 1529 1530 /* locked: maps(read), amap, oanon, anon(if different from oanon) */ 1531 KASSERT(mutex_owned(amap->am_lock)); 1532 KASSERT(anon->an_lock == amap->am_lock); 1533 KASSERT(oanon->an_lock == amap->am_lock); 1534 KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); 1535 1536 /* 1537 * now map the page in. 1538 */ 1539 1540 UVMHIST_LOG(maphist, 1541 " MAPPING: anon: pm=0x%x, va=0x%x, pg=0x%x, promote=%d", 1542 ufi->orig_map->pmap, ufi->orig_rvaddr, pg, flt->promote); 1543 if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr, 1544 VM_PAGE_TO_PHYS(pg), 1545 flt->enter_prot, flt->access_type | PMAP_CANFAIL | 1546 (flt->wire_mapping ? PMAP_WIRED : 0)) != 0) { 1547 1548 /* 1549 * No need to undo what we did; we can simply think of 1550 * this as the pmap throwing away the mapping information. 1551 * 1552 * We do, however, have to go through the ReFault path, 1553 * as the map may change while we're asleep. 1554 */ 1555 1556 uvmfault_unlockall(ufi, amap, uobj); 1557 if (!uvm_reclaimable()) { 1558 UVMHIST_LOG(maphist, 1559 "<- failed. out of VM",0,0,0,0); 1560 /* XXX instrumentation */ 1561 return ENOMEM; 1562 } 1563 /* XXX instrumentation */ 1564 uvm_wait("flt_pmfail1"); 1565 return ERESTART; 1566 } 1567 1568 uvm_fault_upper_done(ufi, flt, anon, pg); 1569 1570 /* 1571 * done case 1! finish up by unlocking everything and returning success 1572 */ 1573 1574 pmap_update(ufi->orig_map->pmap); 1575 uvmfault_unlockall(ufi, amap, uobj); 1576 return 0; 1577 } 1578 1579 /* 1580 * uvm_fault_upper_done: queue upper center page. 1581 */ 1582 1583 static void 1584 uvm_fault_upper_done( 1585 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1586 struct vm_anon *anon, struct vm_page *pg) 1587 { 1588 const bool wire_paging = flt->wire_paging; 1589 1590 UVMHIST_FUNC("uvm_fault_upper_done"); UVMHIST_CALLED(maphist); 1591 1592 /* 1593 * ... update the page queues. 1594 */ 1595 1596 mutex_enter(&uvm_pageqlock); 1597 if (wire_paging) { 1598 uvm_pagewire(pg); 1599 1600 /* 1601 * since the now-wired page cannot be paged out, 1602 * release its swap resources for others to use. 1603 * since an anon with no swap cannot be PG_CLEAN, 1604 * clear its clean flag now. 1605 */ 1606 1607 pg->flags &= ~(PG_CLEAN); 1608 1609 } else { 1610 uvm_pageactivate(pg); 1611 } 1612 mutex_exit(&uvm_pageqlock); 1613 1614 if (wire_paging) { 1615 uvm_anon_dropswap(anon); 1616 } 1617 } 1618 1619 /* 1620 * uvm_fault_lower: handle lower fault. 1621 * 1622 * 1. check uobj 1623 * 1.1. if null, ZFOD. 1624 * 1.2. if not null, look up unnmapped neighbor pages. 1625 * 2. for center page, check if promote. 1626 * 2.1. ZFOD always needs promotion. 1627 * 2.2. other uobjs, when entry is marked COW (usually MAP_PRIVATE vnode). 1628 * 3. if uobj is not ZFOD and page is not found, do i/o. 1629 * 4. dispatch either direct / promote fault. 1630 */ 1631 1632 static int 1633 uvm_fault_lower( 1634 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1635 struct vm_page **pages) 1636 { 1637 #ifdef DIAGNOSTIC 1638 struct vm_amap *amap = ufi->entry->aref.ar_amap; 1639 #endif 1640 struct uvm_object *uobj = ufi->entry->object.uvm_obj; 1641 struct vm_page *uobjpage; 1642 int error; 1643 UVMHIST_FUNC("uvm_fault_lower"); UVMHIST_CALLED(maphist); 1644 1645 /* 1646 * now, if the desired page is not shadowed by the amap and we have 1647 * a backing object that does not have a special fault routine, then 1648 * we ask (with pgo_get) the object for resident pages that we care 1649 * about and attempt to map them in. we do not let pgo_get block 1650 * (PGO_LOCKED). 1651 */ 1652 1653 if (uobj == NULL) { 1654 /* zero fill; don't care neighbor pages */ 1655 uobjpage = NULL; 1656 } else { 1657 uvm_fault_lower_lookup(ufi, flt, pages); 1658 uobjpage = pages[flt->centeridx]; 1659 } 1660 1661 /* 1662 * note that at this point we are done with any front or back pages. 1663 * we are now going to focus on the center page (i.e. the one we've 1664 * faulted on). if we have faulted on the upper (anon) layer 1665 * [i.e. case 1], then the anon we want is anons[centeridx] (we have 1666 * not touched it yet). if we have faulted on the bottom (uobj) 1667 * layer [i.e. case 2] and the page was both present and available, 1668 * then we've got a pointer to it as "uobjpage" and we've already 1669 * made it BUSY. 1670 */ 1671 1672 /* 1673 * locked: 1674 * maps(read), amap(if there), uobj(if !null), uobjpage(if !null) 1675 */ 1676 KASSERT(amap == NULL || mutex_owned(amap->am_lock)); 1677 KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); 1678 KASSERT(uobjpage == NULL || (uobjpage->flags & PG_BUSY) != 0); 1679 1680 /* 1681 * note that uobjpage can not be PGO_DONTCARE at this point. we now 1682 * set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we 1683 * have a backing object, check and see if we are going to promote 1684 * the data up to an anon during the fault. 1685 */ 1686 1687 if (uobj == NULL) { 1688 uobjpage = PGO_DONTCARE; 1689 flt->promote = true; /* always need anon here */ 1690 } else { 1691 KASSERT(uobjpage != PGO_DONTCARE); 1692 flt->promote = flt->cow_now && UVM_ET_ISCOPYONWRITE(ufi->entry); 1693 } 1694 UVMHIST_LOG(maphist, " case 2 fault: promote=%d, zfill=%d", 1695 flt->promote, (uobj == NULL), 0,0); 1696 1697 /* 1698 * if uobjpage is not null then we do not need to do I/O to get the 1699 * uobjpage. 1700 * 1701 * if uobjpage is null, then we need to unlock and ask the pager to 1702 * get the data for us. once we have the data, we need to reverify 1703 * the state the world. we are currently not holding any resources. 1704 */ 1705 1706 if (uobjpage) { 1707 /* update rusage counters */ 1708 curlwp->l_ru.ru_minflt++; 1709 } else { 1710 error = uvm_fault_lower_io(ufi, flt, &uobj, &uobjpage); 1711 if (error != 0) 1712 return error; 1713 } 1714 1715 /* 1716 * locked: 1717 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj) 1718 */ 1719 KASSERT(amap == NULL || mutex_owned(amap->am_lock)); 1720 KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); 1721 KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0); 1722 1723 /* 1724 * notes: 1725 * - at this point uobjpage can not be NULL 1726 * - at this point uobjpage can not be PG_RELEASED (since we checked 1727 * for it above) 1728 * - at this point uobjpage could be PG_WANTED (handle later) 1729 */ 1730 1731 KASSERT(uobjpage != NULL); 1732 KASSERT(uobj == NULL || uobj == uobjpage->uobject); 1733 KASSERT(uobj == NULL || !UVM_OBJ_IS_CLEAN(uobjpage->uobject) || 1734 (uobjpage->flags & PG_CLEAN) != 0); 1735 1736 if (!flt->promote) { 1737 error = uvm_fault_lower_direct(ufi, flt, uobj, uobjpage); 1738 } else { 1739 error = uvm_fault_lower_promote(ufi, flt, uobj, uobjpage); 1740 } 1741 return error; 1742 } 1743 1744 /* 1745 * uvm_fault_lower_lookup: look up on-memory uobj pages. 1746 * 1747 * 1. get on-memory pages. 1748 * 2. if failed, give up (get only center page later). 1749 * 3. if succeeded, enter h/w mapping of neighbor pages. 1750 */ 1751 1752 static void 1753 uvm_fault_lower_lookup( 1754 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1755 struct vm_page **pages) 1756 { 1757 struct uvm_object *uobj = ufi->entry->object.uvm_obj; 1758 int lcv, gotpages; 1759 vaddr_t currva; 1760 UVMHIST_FUNC("uvm_fault_lower_lookup"); UVMHIST_CALLED(maphist); 1761 1762 mutex_enter(uobj->vmobjlock); 1763 /* Locked: maps(read), amap(if there), uobj */ 1764 1765 uvmexp.fltlget++; 1766 gotpages = flt->npages; 1767 (void) uobj->pgops->pgo_get(uobj, 1768 ufi->entry->offset + flt->startva - ufi->entry->start, 1769 pages, &gotpages, flt->centeridx, 1770 flt->access_type & MASK(ufi->entry), ufi->entry->advice, PGO_LOCKED); 1771 1772 KASSERT(mutex_owned(uobj->vmobjlock)); 1773 1774 /* 1775 * check for pages to map, if we got any 1776 */ 1777 1778 if (gotpages == 0) { 1779 pages[flt->centeridx] = NULL; 1780 return; 1781 } 1782 1783 currva = flt->startva; 1784 for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { 1785 struct vm_page *curpg; 1786 1787 curpg = pages[lcv]; 1788 if (curpg == NULL || curpg == PGO_DONTCARE) { 1789 continue; 1790 } 1791 KASSERT(curpg->uobject == uobj); 1792 1793 /* 1794 * if center page is resident and not PG_BUSY|PG_RELEASED 1795 * then pgo_get made it PG_BUSY for us and gave us a handle 1796 * to it. 1797 */ 1798 1799 if (lcv == flt->centeridx) { 1800 UVMHIST_LOG(maphist, " got uobjpage " 1801 "(0x%x) with locked get", 1802 curpg, 0,0,0); 1803 } else { 1804 bool readonly = (curpg->flags & PG_RDONLY) 1805 || (curpg->loan_count > 0) 1806 || UVM_OBJ_NEEDS_WRITEFAULT(curpg->uobject); 1807 1808 uvm_fault_lower_neighbor(ufi, flt, 1809 currva, curpg, readonly); 1810 } 1811 } 1812 pmap_update(ufi->orig_map->pmap); 1813 } 1814 1815 /* 1816 * uvm_fault_lower_neighbor: enter h/w mapping of lower neighbor page. 1817 */ 1818 1819 static void 1820 uvm_fault_lower_neighbor( 1821 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1822 vaddr_t currva, struct vm_page *pg, bool readonly) 1823 { 1824 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1825 1826 /* locked: maps(read), amap(if there), uobj */ 1827 1828 /* 1829 * calling pgo_get with PGO_LOCKED returns us pages which 1830 * are neither busy nor released, so we don't need to check 1831 * for this. we can just directly enter the pages. 1832 */ 1833 1834 mutex_enter(&uvm_pageqlock); 1835 uvm_pageenqueue(pg); 1836 mutex_exit(&uvm_pageqlock); 1837 UVMHIST_LOG(maphist, 1838 " MAPPING: n obj: pm=0x%x, va=0x%x, pg=0x%x", 1839 ufi->orig_map->pmap, currva, pg, 0); 1840 uvmexp.fltnomap++; 1841 1842 /* 1843 * Since this page isn't the page that's actually faulting, 1844 * ignore pmap_enter() failures; it's not critical that we 1845 * enter these right now. 1846 * NOTE: page can't be PG_WANTED or PG_RELEASED because we've 1847 * held the lock the whole time we've had the handle. 1848 */ 1849 KASSERT((pg->flags & PG_PAGEOUT) == 0); 1850 KASSERT((pg->flags & PG_RELEASED) == 0); 1851 KASSERT((pg->flags & PG_WANTED) == 0); 1852 KASSERT(!UVM_OBJ_IS_CLEAN(pg->uobject) || (pg->flags & PG_CLEAN) != 0); 1853 pg->flags &= ~(PG_BUSY); 1854 UVM_PAGE_OWN(pg, NULL); 1855 1856 KASSERT(mutex_owned(pg->uobject->vmobjlock)); 1857 (void) pmap_enter(ufi->orig_map->pmap, currva, 1858 VM_PAGE_TO_PHYS(pg), 1859 readonly ? (flt->enter_prot & ~VM_PROT_WRITE) : 1860 flt->enter_prot & MASK(ufi->entry), 1861 PMAP_CANFAIL | (flt->wire_mapping ? PMAP_WIRED : 0)); 1862 } 1863 1864 /* 1865 * uvm_fault_lower_io: get lower page from backing store. 1866 * 1867 * 1. unlock everything, because i/o will block. 1868 * 2. call pgo_get. 1869 * 3. if failed, recover. 1870 * 4. if succeeded, relock everything and verify things. 1871 */ 1872 1873 static int 1874 uvm_fault_lower_io( 1875 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1876 struct uvm_object **ruobj, struct vm_page **ruobjpage) 1877 { 1878 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1879 struct uvm_object *uobj = *ruobj; 1880 struct vm_page *pg; 1881 bool locked; 1882 int gotpages; 1883 int error; 1884 voff_t uoff; 1885 UVMHIST_FUNC("uvm_fault_lower_io"); UVMHIST_CALLED(maphist); 1886 1887 /* update rusage counters */ 1888 curlwp->l_ru.ru_majflt++; 1889 1890 /* Locked: maps(read), amap(if there), uobj */ 1891 uvmfault_unlockall(ufi, amap, NULL); 1892 1893 /* Locked: uobj */ 1894 KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); 1895 1896 uvmexp.fltget++; 1897 gotpages = 1; 1898 pg = NULL; 1899 uoff = (ufi->orig_rvaddr - ufi->entry->start) + ufi->entry->offset; 1900 error = uobj->pgops->pgo_get(uobj, uoff, &pg, &gotpages, 1901 0, flt->access_type & MASK(ufi->entry), ufi->entry->advice, 1902 PGO_SYNCIO); 1903 /* locked: pg(if no error) */ 1904 1905 /* 1906 * recover from I/O 1907 */ 1908 1909 if (error) { 1910 if (error == EAGAIN) { 1911 UVMHIST_LOG(maphist, 1912 " pgo_get says TRY AGAIN!",0,0,0,0); 1913 kpause("fltagain2", false, hz/2, NULL); 1914 return ERESTART; 1915 } 1916 1917 #if 0 1918 KASSERT(error != ERESTART); 1919 #else 1920 /* XXXUEBS don't re-fault? */ 1921 if (error == ERESTART) 1922 error = EIO; 1923 #endif 1924 1925 UVMHIST_LOG(maphist, "<- pgo_get failed (code %d)", 1926 error, 0,0,0); 1927 return error; 1928 } 1929 1930 /* 1931 * re-verify the state of the world by first trying to relock 1932 * the maps. always relock the object. 1933 */ 1934 1935 locked = uvmfault_relock(ufi); 1936 if (locked && amap) 1937 amap_lock(amap); 1938 1939 /* might be changed */ 1940 uobj = pg->uobject; 1941 1942 mutex_enter(uobj->vmobjlock); 1943 KASSERT((pg->flags & PG_BUSY) != 0); 1944 1945 mutex_enter(&uvm_pageqlock); 1946 uvm_pageactivate(pg); 1947 mutex_exit(&uvm_pageqlock); 1948 1949 /* locked(locked): maps(read), amap(if !null), uobj, pg */ 1950 /* locked(!locked): uobj, pg */ 1951 1952 /* 1953 * verify that the page has not be released and re-verify 1954 * that amap slot is still free. if there is a problem, 1955 * we unlock and clean up. 1956 */ 1957 1958 if ((pg->flags & PG_RELEASED) != 0 || 1959 (locked && amap && amap_lookup(&ufi->entry->aref, 1960 ufi->orig_rvaddr - ufi->entry->start))) { 1961 if (locked) 1962 uvmfault_unlockall(ufi, amap, NULL); 1963 locked = false; 1964 } 1965 1966 /* 1967 * didn't get the lock? release the page and retry. 1968 */ 1969 1970 if (locked == false) { 1971 UVMHIST_LOG(maphist, 1972 " wasn't able to relock after fault: retry", 1973 0,0,0,0); 1974 if (pg->flags & PG_WANTED) { 1975 wakeup(pg); 1976 } 1977 if ((pg->flags & PG_RELEASED) == 0) { 1978 pg->flags &= ~(PG_BUSY | PG_WANTED); 1979 UVM_PAGE_OWN(pg, NULL); 1980 } else { 1981 uvmexp.fltpgrele++; 1982 uvm_pagefree(pg); 1983 } 1984 mutex_exit(uobj->vmobjlock); 1985 return ERESTART; 1986 } 1987 1988 /* 1989 * we have the data in pg which is busy and 1990 * not released. we are holding object lock (so the page 1991 * can't be released on us). 1992 */ 1993 1994 /* locked: maps(read), amap(if !null), uobj, pg */ 1995 1996 *ruobj = uobj; 1997 *ruobjpage = pg; 1998 return 0; 1999 } 2000 2001 /* 2002 * uvm_fault_lower_direct: fault lower center page 2003 * 2004 * 1. adjust flt->enter_prot. 2005 * 2. if page is loaned, resolve. 2006 */ 2007 2008 int 2009 uvm_fault_lower_direct( 2010 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 2011 struct uvm_object *uobj, struct vm_page *uobjpage) 2012 { 2013 struct vm_page *pg; 2014 UVMHIST_FUNC("uvm_fault_lower_direct"); UVMHIST_CALLED(maphist); 2015 2016 /* 2017 * we are not promoting. if the mapping is COW ensure that we 2018 * don't give more access than we should (e.g. when doing a read 2019 * fault on a COPYONWRITE mapping we want to map the COW page in 2020 * R/O even though the entry protection could be R/W). 2021 * 2022 * set "pg" to the page we want to map in (uobjpage, usually) 2023 */ 2024 2025 uvmexp.flt_obj++; 2026 if (UVM_ET_ISCOPYONWRITE(ufi->entry) || 2027 UVM_OBJ_NEEDS_WRITEFAULT(uobjpage->uobject)) 2028 flt->enter_prot &= ~VM_PROT_WRITE; 2029 pg = uobjpage; /* map in the actual object */ 2030 2031 KASSERT(uobjpage != PGO_DONTCARE); 2032 2033 /* 2034 * we are faulting directly on the page. be careful 2035 * about writing to loaned pages... 2036 */ 2037 2038 if (uobjpage->loan_count) { 2039 uvm_fault_lower_direct_loan(ufi, flt, uobj, &pg, &uobjpage); 2040 } 2041 KASSERT(pg == uobjpage); 2042 2043 KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0); 2044 return uvm_fault_lower_enter(ufi, flt, uobj, NULL, pg); 2045 } 2046 2047 /* 2048 * uvm_fault_lower_direct_loan: resolve loaned page. 2049 * 2050 * 1. if not cow'ing, adjust flt->enter_prot. 2051 * 2. if cow'ing, break loan. 2052 */ 2053 2054 static int 2055 uvm_fault_lower_direct_loan( 2056 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 2057 struct uvm_object *uobj, struct vm_page **rpg, 2058 struct vm_page **ruobjpage) 2059 { 2060 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 2061 struct vm_page *pg; 2062 struct vm_page *uobjpage = *ruobjpage; 2063 UVMHIST_FUNC("uvm_fault_lower_direct_loan"); UVMHIST_CALLED(maphist); 2064 2065 if (!flt->cow_now) { 2066 /* read fault: cap the protection at readonly */ 2067 /* cap! */ 2068 flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; 2069 } else { 2070 /* write fault: must break the loan here */ 2071 2072 pg = uvm_loanbreak(uobjpage); 2073 if (pg == NULL) { 2074 2075 /* 2076 * drop ownership of page, it can't be released 2077 */ 2078 2079 if (uobjpage->flags & PG_WANTED) 2080 wakeup(uobjpage); 2081 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 2082 UVM_PAGE_OWN(uobjpage, NULL); 2083 2084 uvmfault_unlockall(ufi, amap, uobj); 2085 UVMHIST_LOG(maphist, 2086 " out of RAM breaking loan, waiting", 2087 0,0,0,0); 2088 uvmexp.fltnoram++; 2089 uvm_wait("flt_noram4"); 2090 return ERESTART; 2091 } 2092 *rpg = pg; 2093 *ruobjpage = pg; 2094 } 2095 return 0; 2096 } 2097 2098 /* 2099 * uvm_fault_lower_promote: promote lower page. 2100 * 2101 * 1. call uvmfault_promote. 2102 * 2. fill in data. 2103 * 3. if not ZFOD, dispose old page. 2104 */ 2105 2106 int 2107 uvm_fault_lower_promote( 2108 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 2109 struct uvm_object *uobj, struct vm_page *uobjpage) 2110 { 2111 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 2112 struct vm_anon *anon; 2113 struct vm_page *pg; 2114 int error; 2115 UVMHIST_FUNC("uvm_fault_lower_promote"); UVMHIST_CALLED(maphist); 2116 2117 KASSERT(amap != NULL); 2118 2119 /* 2120 * If we are going to promote the data to an anon we 2121 * allocate a blank anon here and plug it into our amap. 2122 */ 2123 error = uvmfault_promote(ufi, NULL, uobjpage, 2124 &anon, &flt->anon_spare); 2125 switch (error) { 2126 case 0: 2127 break; 2128 case ERESTART: 2129 return ERESTART; 2130 default: 2131 return error; 2132 } 2133 2134 pg = anon->an_page; 2135 2136 /* 2137 * Fill in the data. 2138 */ 2139 KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0); 2140 2141 if (uobjpage != PGO_DONTCARE) { 2142 uvmexp.flt_prcopy++; 2143 2144 /* 2145 * promote to shared amap? make sure all sharing 2146 * procs see it 2147 */ 2148 2149 if ((amap_flags(amap) & AMAP_SHARED) != 0) { 2150 pmap_page_protect(uobjpage, VM_PROT_NONE); 2151 /* 2152 * XXX: PAGE MIGHT BE WIRED! 2153 */ 2154 } 2155 2156 /* 2157 * dispose of uobjpage. it can't be PG_RELEASED 2158 * since we still hold the object lock. 2159 */ 2160 2161 if (uobjpage->flags & PG_WANTED) { 2162 /* still have the obj lock */ 2163 wakeup(uobjpage); 2164 } 2165 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 2166 UVM_PAGE_OWN(uobjpage, NULL); 2167 2168 UVMHIST_LOG(maphist, 2169 " promote uobjpage 0x%x to anon/page 0x%x/0x%x", 2170 uobjpage, anon, pg, 0); 2171 2172 } else { 2173 uvmexp.flt_przero++; 2174 2175 /* 2176 * Page is zero'd and marked dirty by 2177 * uvmfault_promote(). 2178 */ 2179 2180 UVMHIST_LOG(maphist," zero fill anon/page 0x%x/0%x", 2181 anon, pg, 0, 0); 2182 } 2183 2184 return uvm_fault_lower_enter(ufi, flt, uobj, anon, pg); 2185 } 2186 2187 /* 2188 * uvm_fault_lower_enter: enter h/w mapping of lower page or anon page promoted 2189 * from the lower page. 2190 */ 2191 2192 int 2193 uvm_fault_lower_enter( 2194 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 2195 struct uvm_object *uobj, 2196 struct vm_anon *anon, struct vm_page *pg) 2197 { 2198 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 2199 int error; 2200 UVMHIST_FUNC("uvm_fault_lower_enter"); UVMHIST_CALLED(maphist); 2201 2202 /* 2203 * Locked: 2204 * 2205 * maps(read), amap(if !null), uobj(if !null), 2206 * anon(if !null), pg(if anon), unlock_uobj(if !null) 2207 * 2208 * Note: pg is either the uobjpage or the new page in the new anon. 2209 */ 2210 KASSERT(amap == NULL || mutex_owned(amap->am_lock)); 2211 KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); 2212 KASSERT(anon == NULL || anon->an_lock == amap->am_lock); 2213 KASSERT((pg->flags & PG_BUSY) != 0); 2214 2215 /* 2216 * all resources are present. we can now map it in and free our 2217 * resources. 2218 */ 2219 2220 UVMHIST_LOG(maphist, 2221 " MAPPING: case2: pm=0x%x, va=0x%x, pg=0x%x, promote=%d", 2222 ufi->orig_map->pmap, ufi->orig_rvaddr, pg, flt->promote); 2223 KASSERT((flt->access_type & VM_PROT_WRITE) == 0 || 2224 (pg->flags & PG_RDONLY) == 0); 2225 if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr, 2226 VM_PAGE_TO_PHYS(pg), 2227 (pg->flags & PG_RDONLY) != 0 ? 2228 flt->enter_prot & ~VM_PROT_WRITE : flt->enter_prot, 2229 flt->access_type | PMAP_CANFAIL | 2230 (flt->wire_mapping ? PMAP_WIRED : 0)) != 0) { 2231 2232 /* 2233 * No need to undo what we did; we can simply think of 2234 * this as the pmap throwing away the mapping information. 2235 * 2236 * We do, however, have to go through the ReFault path, 2237 * as the map may change while we're asleep. 2238 */ 2239 2240 /* 2241 * ensure that the page is queued in the case that 2242 * we just promoted the page. 2243 */ 2244 2245 mutex_enter(&uvm_pageqlock); 2246 uvm_pageenqueue(pg); 2247 mutex_exit(&uvm_pageqlock); 2248 2249 if (pg->flags & PG_WANTED) 2250 wakeup(pg); 2251 2252 /* 2253 * note that pg can't be PG_RELEASED since we did not drop 2254 * the object lock since the last time we checked. 2255 */ 2256 KASSERT((pg->flags & PG_RELEASED) == 0); 2257 2258 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 2259 UVM_PAGE_OWN(pg, NULL); 2260 2261 uvmfault_unlockall(ufi, amap, uobj); 2262 if (!uvm_reclaimable()) { 2263 UVMHIST_LOG(maphist, 2264 "<- failed. out of VM",0,0,0,0); 2265 /* XXX instrumentation */ 2266 error = ENOMEM; 2267 return error; 2268 } 2269 /* XXX instrumentation */ 2270 uvm_wait("flt_pmfail2"); 2271 return ERESTART; 2272 } 2273 2274 uvm_fault_lower_done(ufi, flt, uobj, pg); 2275 2276 /* 2277 * note that pg can't be PG_RELEASED since we did not drop the object 2278 * lock since the last time we checked. 2279 */ 2280 KASSERT((pg->flags & PG_RELEASED) == 0); 2281 if (pg->flags & PG_WANTED) 2282 wakeup(pg); 2283 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 2284 UVM_PAGE_OWN(pg, NULL); 2285 2286 pmap_update(ufi->orig_map->pmap); 2287 uvmfault_unlockall(ufi, amap, uobj); 2288 2289 UVMHIST_LOG(maphist, "<- done (SUCCESS!)",0,0,0,0); 2290 return 0; 2291 } 2292 2293 /* 2294 * uvm_fault_lower_done: queue lower center page. 2295 */ 2296 2297 void 2298 uvm_fault_lower_done( 2299 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 2300 struct uvm_object *uobj, struct vm_page *pg) 2301 { 2302 bool dropswap = false; 2303 2304 UVMHIST_FUNC("uvm_fault_lower_done"); UVMHIST_CALLED(maphist); 2305 2306 mutex_enter(&uvm_pageqlock); 2307 if (flt->wire_paging) { 2308 uvm_pagewire(pg); 2309 if (pg->pqflags & PQ_AOBJ) { 2310 2311 /* 2312 * since the now-wired page cannot be paged out, 2313 * release its swap resources for others to use. 2314 * since an aobj page with no swap cannot be PG_CLEAN, 2315 * clear its clean flag now. 2316 */ 2317 2318 KASSERT(uobj != NULL); 2319 pg->flags &= ~(PG_CLEAN); 2320 dropswap = true; 2321 } 2322 } else { 2323 uvm_pageactivate(pg); 2324 } 2325 mutex_exit(&uvm_pageqlock); 2326 2327 if (dropswap) { 2328 uao_dropswap(uobj, pg->offset >> PAGE_SHIFT); 2329 } 2330 } 2331 2332 2333 /* 2334 * uvm_fault_wire: wire down a range of virtual addresses in a map. 2335 * 2336 * => map may be read-locked by caller, but MUST NOT be write-locked. 2337 * => if map is read-locked, any operations which may cause map to 2338 * be write-locked in uvm_fault() must be taken care of by 2339 * the caller. See uvm_map_pageable(). 2340 */ 2341 2342 int 2343 uvm_fault_wire(struct vm_map *map, vaddr_t start, vaddr_t end, 2344 vm_prot_t access_type, int maxprot) 2345 { 2346 vaddr_t va; 2347 int error; 2348 2349 /* 2350 * now fault it in a page at a time. if the fault fails then we have 2351 * to undo what we have done. note that in uvm_fault VM_PROT_NONE 2352 * is replaced with the max protection if fault_type is VM_FAULT_WIRE. 2353 */ 2354 2355 /* 2356 * XXX work around overflowing a vaddr_t. this prevents us from 2357 * wiring the last page in the address space, though. 2358 */ 2359 if (start > end) { 2360 return EFAULT; 2361 } 2362 2363 for (va = start; va < end; va += PAGE_SIZE) { 2364 error = uvm_fault_internal(map, va, access_type, 2365 (maxprot ? UVM_FAULT_MAXPROT : 0) | UVM_FAULT_WIRE); 2366 if (error) { 2367 if (va != start) { 2368 uvm_fault_unwire(map, start, va); 2369 } 2370 return error; 2371 } 2372 } 2373 return 0; 2374 } 2375 2376 /* 2377 * uvm_fault_unwire(): unwire range of virtual space. 2378 */ 2379 2380 void 2381 uvm_fault_unwire(struct vm_map *map, vaddr_t start, vaddr_t end) 2382 { 2383 vm_map_lock_read(map); 2384 uvm_fault_unwire_locked(map, start, end); 2385 vm_map_unlock_read(map); 2386 } 2387 2388 /* 2389 * uvm_fault_unwire_locked(): the guts of uvm_fault_unwire(). 2390 * 2391 * => map must be at least read-locked. 2392 */ 2393 2394 void 2395 uvm_fault_unwire_locked(struct vm_map *map, vaddr_t start, vaddr_t end) 2396 { 2397 struct vm_map_entry *entry, *oentry; 2398 pmap_t pmap = vm_map_pmap(map); 2399 vaddr_t va; 2400 paddr_t pa; 2401 struct vm_page *pg; 2402 2403 /* 2404 * we assume that the area we are unwiring has actually been wired 2405 * in the first place. this means that we should be able to extract 2406 * the PAs from the pmap. we also lock out the page daemon so that 2407 * we can call uvm_pageunwire. 2408 */ 2409 2410 /* 2411 * find the beginning map entry for the region. 2412 */ 2413 2414 KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map)); 2415 if (uvm_map_lookup_entry(map, start, &entry) == false) 2416 panic("uvm_fault_unwire_locked: address not in map"); 2417 2418 oentry = NULL; 2419 for (va = start; va < end; va += PAGE_SIZE) { 2420 if (pmap_extract(pmap, va, &pa) == false) 2421 continue; 2422 2423 /* 2424 * find the map entry for the current address. 2425 */ 2426 2427 KASSERT(va >= entry->start); 2428 while (va >= entry->end) { 2429 KASSERT(entry->next != &map->header && 2430 entry->next->start <= entry->end); 2431 entry = entry->next; 2432 } 2433 2434 /* 2435 * lock it. 2436 */ 2437 2438 if (entry != oentry) { 2439 if (oentry != NULL) { 2440 mutex_exit(&uvm_pageqlock); 2441 uvm_map_unlock_entry(oentry); 2442 } 2443 uvm_map_lock_entry(entry); 2444 mutex_enter(&uvm_pageqlock); 2445 oentry = entry; 2446 } 2447 2448 /* 2449 * if the entry is no longer wired, tell the pmap. 2450 */ 2451 2452 if (VM_MAPENT_ISWIRED(entry) == 0) 2453 pmap_unwire(pmap, va); 2454 2455 pg = PHYS_TO_VM_PAGE(pa); 2456 if (pg) 2457 uvm_pageunwire(pg); 2458 } 2459 2460 if (oentry != NULL) { 2461 mutex_exit(&uvm_pageqlock); 2462 uvm_map_unlock_entry(entry); 2463 } 2464 } 2465