1 /* $NetBSD: uvm_fault.c,v 1.182 2011/02/10 21:05:52 skrll 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 1.182 2011/02/10 21:05:52 skrll 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/proc.h> 43 #include <sys/malloc.h> 44 #include <sys/mman.h> 45 46 #include <uvm/uvm.h> 47 48 /* 49 * 50 * a word on page faults: 51 * 52 * types of page faults we handle: 53 * 54 * CASE 1: upper layer faults CASE 2: lower layer faults 55 * 56 * CASE 1A CASE 1B CASE 2A CASE 2B 57 * read/write1 write>1 read/write +-cow_write/zero 58 * | | | | 59 * +--|--+ +--|--+ +-----+ + | + | +-----+ 60 * amap | V | | ---------> new | | | | ^ | 61 * +-----+ +-----+ +-----+ + | + | +--|--+ 62 * | | | 63 * +-----+ +-----+ +--|--+ | +--|--+ 64 * uobj | d/c | | d/c | | V | +----+ | 65 * +-----+ +-----+ +-----+ +-----+ 66 * 67 * d/c = don't care 68 * 69 * case [0]: layerless fault 70 * no amap or uobj is present. this is an error. 71 * 72 * case [1]: upper layer fault [anon active] 73 * 1A: [read] or [write with anon->an_ref == 1] 74 * I/O takes place in upper level anon and uobj is not touched. 75 * 1B: [write with anon->an_ref > 1] 76 * new anon is alloc'd and data is copied off ["COW"] 77 * 78 * case [2]: lower layer fault [uobj] 79 * 2A: [read on non-NULL uobj] or [write to non-copy_on_write area] 80 * I/O takes place directly in object. 81 * 2B: [write to copy_on_write] or [read on NULL uobj] 82 * data is "promoted" from uobj to a new anon. 83 * if uobj is null, then we zero fill. 84 * 85 * we follow the standard UVM locking protocol ordering: 86 * 87 * MAPS => AMAP => UOBJ => ANON => PAGE QUEUES (PQ) 88 * we hold a PG_BUSY page if we unlock for I/O 89 * 90 * 91 * the code is structured as follows: 92 * 93 * - init the "IN" params in the ufi structure 94 * ReFault: (ERESTART returned to the loop in uvm_fault_internal) 95 * - do lookups [locks maps], check protection, handle needs_copy 96 * - check for case 0 fault (error) 97 * - establish "range" of fault 98 * - if we have an amap lock it and extract the anons 99 * - if sequential advice deactivate pages behind us 100 * - at the same time check pmap for unmapped areas and anon for pages 101 * that we could map in (and do map it if found) 102 * - check object for resident pages that we could map in 103 * - if (case 2) goto Case2 104 * - >>> handle case 1 105 * - ensure source anon is resident in RAM 106 * - if case 1B alloc new anon and copy from source 107 * - map the correct page in 108 * Case2: 109 * - >>> handle case 2 110 * - ensure source page is resident (if uobj) 111 * - if case 2B alloc new anon and copy from source (could be zero 112 * fill if uobj == NULL) 113 * - map the correct page in 114 * - done! 115 * 116 * note on paging: 117 * if we have to do I/O we place a PG_BUSY page in the correct object, 118 * unlock everything, and do the I/O. when I/O is done we must reverify 119 * the state of the world before assuming that our data structures are 120 * valid. [because mappings could change while the map is unlocked] 121 * 122 * alternative 1: unbusy the page in question and restart the page fault 123 * from the top (ReFault). this is easy but does not take advantage 124 * of the information that we already have from our previous lookup, 125 * although it is possible that the "hints" in the vm_map will help here. 126 * 127 * alternative 2: the system already keeps track of a "version" number of 128 * a map. [i.e. every time you write-lock a map (e.g. to change a 129 * mapping) you bump the version number up by one...] so, we can save 130 * the version number of the map before we release the lock and start I/O. 131 * then when I/O is done we can relock and check the version numbers 132 * to see if anything changed. this might save us some over 1 because 133 * we don't have to unbusy the page and may be less compares(?). 134 * 135 * alternative 3: put in backpointers or a way to "hold" part of a map 136 * in place while I/O is in progress. this could be complex to 137 * implement (especially with structures like amap that can be referenced 138 * by multiple map entries, and figuring out what should wait could be 139 * complex as well...). 140 * 141 * we use alternative 2. given that we are multi-threaded now we may want 142 * to reconsider the choice. 143 */ 144 145 /* 146 * local data structures 147 */ 148 149 struct uvm_advice { 150 int advice; 151 int nback; 152 int nforw; 153 }; 154 155 /* 156 * page range array: 157 * note: index in array must match "advice" value 158 * XXX: borrowed numbers from freebsd. do they work well for us? 159 */ 160 161 static const struct uvm_advice uvmadvice[] = { 162 { MADV_NORMAL, 3, 4 }, 163 { MADV_RANDOM, 0, 0 }, 164 { MADV_SEQUENTIAL, 8, 7}, 165 }; 166 167 #define UVM_MAXRANGE 16 /* must be MAX() of nback+nforw+1 */ 168 169 /* 170 * private prototypes 171 */ 172 173 /* 174 * inline functions 175 */ 176 177 /* 178 * uvmfault_anonflush: try and deactivate pages in specified anons 179 * 180 * => does not have to deactivate page if it is busy 181 */ 182 183 static inline void 184 uvmfault_anonflush(struct vm_anon **anons, int n) 185 { 186 int lcv; 187 struct vm_page *pg; 188 189 for (lcv = 0; lcv < n; lcv++) { 190 if (anons[lcv] == NULL) 191 continue; 192 mutex_enter(&anons[lcv]->an_lock); 193 pg = anons[lcv]->an_page; 194 if (pg && (pg->flags & PG_BUSY) == 0) { 195 mutex_enter(&uvm_pageqlock); 196 if (pg->wire_count == 0) { 197 uvm_pagedeactivate(pg); 198 } 199 mutex_exit(&uvm_pageqlock); 200 } 201 mutex_exit(&anons[lcv]->an_lock); 202 } 203 } 204 205 /* 206 * normal functions 207 */ 208 209 /* 210 * uvmfault_amapcopy: clear "needs_copy" in a map. 211 * 212 * => called with VM data structures unlocked (usually, see below) 213 * => we get a write lock on the maps and clear needs_copy for a VA 214 * => if we are out of RAM we sleep (waiting for more) 215 */ 216 217 static void 218 uvmfault_amapcopy(struct uvm_faultinfo *ufi) 219 { 220 for (;;) { 221 222 /* 223 * no mapping? give up. 224 */ 225 226 if (uvmfault_lookup(ufi, true) == false) 227 return; 228 229 /* 230 * copy if needed. 231 */ 232 233 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) 234 amap_copy(ufi->map, ufi->entry, AMAP_COPY_NOWAIT, 235 ufi->orig_rvaddr, ufi->orig_rvaddr + 1); 236 237 /* 238 * didn't work? must be out of RAM. unlock and sleep. 239 */ 240 241 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 242 uvmfault_unlockmaps(ufi, true); 243 uvm_wait("fltamapcopy"); 244 continue; 245 } 246 247 /* 248 * got it! unlock and return. 249 */ 250 251 uvmfault_unlockmaps(ufi, true); 252 return; 253 } 254 /*NOTREACHED*/ 255 } 256 257 /* 258 * uvmfault_anonget: get data in an anon into a non-busy, non-released 259 * page in that anon. 260 * 261 * => maps, amap, and anon locked by caller. 262 * => if we fail (result != 0) we unlock everything. 263 * => if we are successful, we return with everything still locked. 264 * => we don't move the page on the queues [gets moved later] 265 * => if we allocate a new page [we_own], it gets put on the queues. 266 * either way, the result is that the page is on the queues at return time 267 * => for pages which are on loan from a uvm_object (and thus are not 268 * owned by the anon): if successful, we return with the owning object 269 * locked. the caller must unlock this object when it unlocks everything 270 * else. 271 */ 272 273 int 274 uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap, 275 struct vm_anon *anon) 276 { 277 bool we_own; /* we own anon's page? */ 278 bool locked; /* did we relock? */ 279 struct vm_page *pg; 280 int error; 281 UVMHIST_FUNC("uvmfault_anonget"); UVMHIST_CALLED(maphist); 282 283 KASSERT(mutex_owned(&anon->an_lock)); 284 285 error = 0; 286 uvmexp.fltanget++; 287 /* bump rusage counters */ 288 if (anon->an_page) 289 curlwp->l_ru.ru_minflt++; 290 else 291 curlwp->l_ru.ru_majflt++; 292 293 /* 294 * loop until we get it, or fail. 295 */ 296 297 for (;;) { 298 we_own = false; /* true if we set PG_BUSY on a page */ 299 pg = anon->an_page; 300 301 /* 302 * if there is a resident page and it is loaned, then anon 303 * may not own it. call out to uvm_anon_lockpage() to ensure 304 * the real owner of the page has been identified and locked. 305 */ 306 307 if (pg && pg->loan_count) 308 pg = uvm_anon_lockloanpg(anon); 309 310 /* 311 * page there? make sure it is not busy/released. 312 */ 313 314 if (pg) { 315 316 /* 317 * at this point, if the page has a uobject [meaning 318 * we have it on loan], then that uobject is locked 319 * by us! if the page is busy, we drop all the 320 * locks (including uobject) and try again. 321 */ 322 323 if ((pg->flags & PG_BUSY) == 0) { 324 UVMHIST_LOG(maphist, "<- OK",0,0,0,0); 325 return (0); 326 } 327 pg->flags |= PG_WANTED; 328 uvmexp.fltpgwait++; 329 330 /* 331 * the last unlock must be an atomic unlock+wait on 332 * the owner of page 333 */ 334 335 if (pg->uobject) { /* owner is uobject ? */ 336 uvmfault_unlockall(ufi, amap, NULL, anon); 337 UVMHIST_LOG(maphist, " unlock+wait on uobj",0, 338 0,0,0); 339 UVM_UNLOCK_AND_WAIT(pg, 340 &pg->uobject->vmobjlock, 341 false, "anonget1",0); 342 } else { 343 /* anon owns page */ 344 uvmfault_unlockall(ufi, amap, NULL, NULL); 345 UVMHIST_LOG(maphist, " unlock+wait on anon",0, 346 0,0,0); 347 UVM_UNLOCK_AND_WAIT(pg,&anon->an_lock,0, 348 "anonget2",0); 349 } 350 } else { 351 #if defined(VMSWAP) 352 353 /* 354 * no page, we must try and bring it in. 355 */ 356 357 pg = uvm_pagealloc(NULL, 358 ufi != NULL ? ufi->orig_rvaddr : 0, 359 anon, UVM_FLAG_COLORMATCH); 360 if (pg == NULL) { /* out of RAM. */ 361 uvmfault_unlockall(ufi, amap, NULL, anon); 362 uvmexp.fltnoram++; 363 UVMHIST_LOG(maphist, " noram -- UVM_WAIT",0, 364 0,0,0); 365 if (!uvm_reclaimable()) { 366 return ENOMEM; 367 } 368 uvm_wait("flt_noram1"); 369 } else { 370 /* we set the PG_BUSY bit */ 371 we_own = true; 372 uvmfault_unlockall(ufi, amap, NULL, anon); 373 374 /* 375 * we are passing a PG_BUSY+PG_FAKE+PG_CLEAN 376 * page into the uvm_swap_get function with 377 * all data structures unlocked. note that 378 * it is ok to read an_swslot here because 379 * we hold PG_BUSY on the page. 380 */ 381 uvmexp.pageins++; 382 error = uvm_swap_get(pg, anon->an_swslot, 383 PGO_SYNCIO); 384 385 /* 386 * we clean up after the i/o below in the 387 * "we_own" case 388 */ 389 } 390 #else /* defined(VMSWAP) */ 391 panic("%s: no page", __func__); 392 #endif /* defined(VMSWAP) */ 393 } 394 395 /* 396 * now relock and try again 397 */ 398 399 locked = uvmfault_relock(ufi); 400 if (locked && amap != NULL) { 401 amap_lock(amap); 402 } 403 if (locked || we_own) 404 mutex_enter(&anon->an_lock); 405 406 /* 407 * if we own the page (i.e. we set PG_BUSY), then we need 408 * to clean up after the I/O. there are three cases to 409 * consider: 410 * [1] page released during I/O: free anon and ReFault. 411 * [2] I/O not OK. free the page and cause the fault 412 * to fail. 413 * [3] I/O OK! activate the page and sync with the 414 * non-we_own case (i.e. drop anon lock if not locked). 415 */ 416 417 if (we_own) { 418 #if defined(VMSWAP) 419 if (pg->flags & PG_WANTED) { 420 wakeup(pg); 421 } 422 if (error) { 423 424 /* 425 * remove the swap slot from the anon 426 * and mark the anon as having no real slot. 427 * don't free the swap slot, thus preventing 428 * it from being used again. 429 */ 430 431 if (anon->an_swslot > 0) 432 uvm_swap_markbad(anon->an_swslot, 1); 433 anon->an_swslot = SWSLOT_BAD; 434 435 if ((pg->flags & PG_RELEASED) != 0) 436 goto released; 437 438 /* 439 * note: page was never !PG_BUSY, so it 440 * can't be mapped and thus no need to 441 * pmap_page_protect it... 442 */ 443 444 mutex_enter(&uvm_pageqlock); 445 uvm_pagefree(pg); 446 mutex_exit(&uvm_pageqlock); 447 448 if (locked) 449 uvmfault_unlockall(ufi, amap, NULL, 450 anon); 451 else 452 mutex_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 unlocked amap. 463 */ 464 465 if (locked) 466 uvmfault_unlockall(ufi, amap, NULL, 467 NULL); 468 469 uvm_anon_release(anon); 470 471 if (error) { 472 UVMHIST_LOG(maphist, 473 "<- ERROR/RELEASED", 0,0,0,0); 474 return error; 475 } 476 477 UVMHIST_LOG(maphist, "<- RELEASED", 0,0,0,0); 478 return ERESTART; 479 } 480 481 /* 482 * we've successfully read the page, activate it. 483 */ 484 485 mutex_enter(&uvm_pageqlock); 486 uvm_pageactivate(pg); 487 mutex_exit(&uvm_pageqlock); 488 pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE); 489 UVM_PAGE_OWN(pg, NULL); 490 if (!locked) 491 mutex_exit(&anon->an_lock); 492 #else /* defined(VMSWAP) */ 493 panic("%s: we_own", __func__); 494 #endif /* defined(VMSWAP) */ 495 } 496 497 /* 498 * we were not able to relock. restart fault. 499 */ 500 501 if (!locked) { 502 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 503 return (ERESTART); 504 } 505 506 /* 507 * verify no one has touched the amap and moved the anon on us. 508 */ 509 510 if (ufi != NULL && 511 amap_lookup(&ufi->entry->aref, 512 ufi->orig_rvaddr - ufi->entry->start) != anon) { 513 514 uvmfault_unlockall(ufi, amap, NULL, anon); 515 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 516 return (ERESTART); 517 } 518 519 /* 520 * try it again! 521 */ 522 523 uvmexp.fltanretry++; 524 continue; 525 } 526 /*NOTREACHED*/ 527 } 528 529 /* 530 * uvmfault_promote: promote data to a new anon. used for 1B and 2B. 531 * 532 * 1. allocate an anon and a page. 533 * 2. fill its contents. 534 * 3. put it into amap. 535 * 536 * => if we fail (result != 0) we unlock everything. 537 * => on success, return a new locked anon via 'nanon'. 538 * (*nanon)->an_page will be a resident, locked, dirty page. 539 */ 540 541 static int 542 uvmfault_promote(struct uvm_faultinfo *ufi, 543 struct vm_anon *oanon, 544 struct vm_page *uobjpage, 545 struct vm_anon **nanon, /* OUT: allocated anon */ 546 struct vm_anon **spare) 547 { 548 struct vm_amap *amap = ufi->entry->aref.ar_amap; 549 struct uvm_object *uobj; 550 struct vm_anon *anon; 551 struct vm_page *pg; 552 struct vm_page *opg; 553 int error; 554 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 555 556 if (oanon) { 557 /* anon COW */ 558 opg = oanon->an_page; 559 KASSERT(opg != NULL); 560 KASSERT(opg->uobject == NULL || opg->loan_count > 0); 561 } else if (uobjpage != PGO_DONTCARE) { 562 /* object-backed COW */ 563 opg = uobjpage; 564 } else { 565 /* ZFOD */ 566 opg = NULL; 567 } 568 if (opg != NULL) { 569 uobj = opg->uobject; 570 } else { 571 uobj = NULL; 572 } 573 574 KASSERT(amap != NULL); 575 KASSERT(uobjpage != NULL); 576 KASSERT(uobjpage == PGO_DONTCARE || (uobjpage->flags & PG_BUSY) != 0); 577 KASSERT(mutex_owned(&amap->am_l)); 578 KASSERT(oanon == NULL || mutex_owned(&oanon->an_lock)); 579 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock)); 580 #if 0 581 KASSERT(*spare == NULL || !mutex_owned(&(*spare)->an_lock)); 582 #endif 583 584 if (*spare != NULL) { 585 anon = *spare; 586 *spare = NULL; 587 mutex_enter(&anon->an_lock); 588 } else if (ufi->map != kernel_map) { 589 anon = uvm_analloc(); 590 } else { 591 UVMHIST_LOG(maphist, "kernel_map, unlock and retry", 0,0,0,0); 592 593 /* 594 * we can't allocate anons with kernel_map locked. 595 */ 596 597 uvm_page_unbusy(&uobjpage, 1); 598 uvmfault_unlockall(ufi, amap, uobj, oanon); 599 600 *spare = uvm_analloc(); 601 if (*spare == NULL) { 602 goto nomem; 603 } 604 mutex_exit(&(*spare)->an_lock); 605 error = ERESTART; 606 goto done; 607 } 608 if (anon) { 609 610 /* 611 * The new anon is locked. 612 * 613 * if opg == NULL, we want a zero'd, dirty page, 614 * so have uvm_pagealloc() do that for us. 615 */ 616 617 pg = uvm_pagealloc(NULL, ufi->orig_rvaddr, anon, 618 UVM_FLAG_COLORMATCH | (opg == NULL ? UVM_PGA_ZERO : 0)); 619 } else { 620 pg = NULL; 621 } 622 623 /* 624 * out of memory resources? 625 */ 626 627 if (pg == NULL) { 628 /* save anon for the next try. */ 629 if (anon != NULL) { 630 mutex_exit(&anon->an_lock); 631 *spare = anon; 632 } 633 634 /* unlock and fail ... */ 635 uvm_page_unbusy(&uobjpage, 1); 636 uvmfault_unlockall(ufi, amap, uobj, oanon); 637 nomem: 638 if (!uvm_reclaimable()) { 639 UVMHIST_LOG(maphist, "out of VM", 0,0,0,0); 640 uvmexp.fltnoanon++; 641 error = ENOMEM; 642 goto done; 643 } 644 645 UVMHIST_LOG(maphist, "out of RAM, waiting for more", 0,0,0,0); 646 uvmexp.fltnoram++; 647 uvm_wait("flt_noram5"); 648 error = ERESTART; 649 goto done; 650 } 651 652 /* copy page [pg now dirty] */ 653 if (opg) { 654 uvm_pagecopy(opg, pg); 655 } 656 657 amap_add(&ufi->entry->aref, ufi->orig_rvaddr - ufi->entry->start, anon, 658 oanon != NULL); 659 660 *nanon = anon; 661 error = 0; 662 done: 663 return error; 664 } 665 666 667 /* 668 * F A U L T - m a i n e n t r y p o i n t 669 */ 670 671 /* 672 * uvm_fault: page fault handler 673 * 674 * => called from MD code to resolve a page fault 675 * => VM data structures usually should be unlocked. however, it is 676 * possible to call here with the main map locked if the caller 677 * gets a write lock, sets it recusive, and then calls us (c.f. 678 * uvm_map_pageable). this should be avoided because it keeps 679 * the map locked off during I/O. 680 * => MUST NEVER BE CALLED IN INTERRUPT CONTEXT 681 */ 682 683 #define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \ 684 ~VM_PROT_WRITE : VM_PROT_ALL) 685 686 /* fault_flag values passed from uvm_fault_wire to uvm_fault_internal */ 687 #define UVM_FAULT_WIRE (1 << 0) 688 #define UVM_FAULT_MAXPROT (1 << 1) 689 690 struct uvm_faultctx { 691 vm_prot_t access_type; 692 vm_prot_t enter_prot; 693 vaddr_t startva; 694 int npages; 695 int centeridx; 696 struct vm_anon *anon_spare; 697 bool wire_mapping; 698 bool narrow; 699 bool wire_paging; 700 bool cow_now; 701 bool promote; 702 }; 703 704 static inline int uvm_fault_check( 705 struct uvm_faultinfo *, struct uvm_faultctx *, 706 struct vm_anon ***, bool); 707 708 static int uvm_fault_upper( 709 struct uvm_faultinfo *, struct uvm_faultctx *, 710 struct vm_anon **); 711 static inline int uvm_fault_upper_lookup( 712 struct uvm_faultinfo *, const struct uvm_faultctx *, 713 struct vm_anon **, struct vm_page **); 714 static inline void uvm_fault_upper_neighbor( 715 struct uvm_faultinfo *, const struct uvm_faultctx *, 716 vaddr_t, struct vm_page *, bool); 717 static inline int uvm_fault_upper_loan( 718 struct uvm_faultinfo *, struct uvm_faultctx *, 719 struct vm_anon *, struct uvm_object **); 720 static inline int uvm_fault_upper_promote( 721 struct uvm_faultinfo *, struct uvm_faultctx *, 722 struct uvm_object *, struct vm_anon *); 723 static inline int uvm_fault_upper_direct( 724 struct uvm_faultinfo *, struct uvm_faultctx *, 725 struct uvm_object *, struct vm_anon *); 726 static int uvm_fault_upper_enter( 727 struct uvm_faultinfo *, const struct uvm_faultctx *, 728 struct uvm_object *, struct vm_anon *, 729 struct vm_page *, struct vm_anon *); 730 static inline void uvm_fault_upper_done( 731 struct uvm_faultinfo *, const struct uvm_faultctx *, 732 struct vm_anon *, struct vm_page *); 733 734 static int uvm_fault_lower( 735 struct uvm_faultinfo *, struct uvm_faultctx *, 736 struct vm_page **); 737 static inline void uvm_fault_lower_lookup( 738 struct uvm_faultinfo *, const struct uvm_faultctx *, 739 struct vm_page **); 740 static inline void uvm_fault_lower_neighbor( 741 struct uvm_faultinfo *, const struct uvm_faultctx *, 742 vaddr_t, struct vm_page *, bool); 743 static inline int uvm_fault_lower_io( 744 struct uvm_faultinfo *, const struct uvm_faultctx *, 745 struct uvm_object **, struct vm_page **); 746 static inline int uvm_fault_lower_direct( 747 struct uvm_faultinfo *, struct uvm_faultctx *, 748 struct uvm_object *, struct vm_page *); 749 static inline int uvm_fault_lower_direct_loan( 750 struct uvm_faultinfo *, struct uvm_faultctx *, 751 struct uvm_object *, struct vm_page **, 752 struct vm_page **); 753 static inline int uvm_fault_lower_promote( 754 struct uvm_faultinfo *, struct uvm_faultctx *, 755 struct uvm_object *, struct vm_page *); 756 static int uvm_fault_lower_enter( 757 struct uvm_faultinfo *, const struct uvm_faultctx *, 758 struct uvm_object *, 759 struct vm_anon *, struct vm_page *, 760 struct vm_page *); 761 static inline void uvm_fault_lower_done( 762 struct uvm_faultinfo *, const struct uvm_faultctx *, 763 struct uvm_object *, struct vm_page *); 764 765 int 766 uvm_fault_internal(struct vm_map *orig_map, vaddr_t vaddr, 767 vm_prot_t access_type, int fault_flag) 768 { 769 struct uvm_faultinfo ufi; 770 struct uvm_faultctx flt = { 771 .access_type = access_type, 772 773 /* don't look for neighborhood * pages on "wire" fault */ 774 .narrow = (fault_flag & UVM_FAULT_WIRE) != 0, 775 776 /* "wire" fault causes wiring of both mapping and paging */ 777 .wire_mapping = (fault_flag & UVM_FAULT_WIRE) != 0, 778 .wire_paging = (fault_flag & UVM_FAULT_WIRE) != 0, 779 }; 780 const bool maxprot = (fault_flag & UVM_FAULT_MAXPROT) != 0; 781 struct vm_anon *anons_store[UVM_MAXRANGE], **anons; 782 struct vm_page *pages_store[UVM_MAXRANGE], **pages; 783 int error; 784 UVMHIST_FUNC("uvm_fault"); UVMHIST_CALLED(maphist); 785 786 UVMHIST_LOG(maphist, "(map=0x%x, vaddr=0x%x, at=%d, ff=%d)", 787 orig_map, vaddr, access_type, fault_flag); 788 789 curcpu()->ci_data.cpu_nfault++; 790 791 /* 792 * init the IN parameters in the ufi 793 */ 794 795 ufi.orig_map = orig_map; 796 ufi.orig_rvaddr = trunc_page(vaddr); 797 ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */ 798 799 error = ERESTART; 800 while (error == ERESTART) { 801 anons = anons_store; 802 pages = pages_store; 803 804 error = uvm_fault_check(&ufi, &flt, &anons, maxprot); 805 if (error != 0) 806 continue; 807 808 error = uvm_fault_upper_lookup(&ufi, &flt, anons, pages); 809 if (error != 0) 810 continue; 811 812 if (pages[flt.centeridx] == PGO_DONTCARE) 813 error = uvm_fault_upper(&ufi, &flt, anons); 814 else { 815 struct uvm_object * const uobj = 816 ufi.entry->object.uvm_obj; 817 818 if (uobj && uobj->pgops->pgo_fault != NULL) { 819 /* 820 * invoke "special" fault routine. 821 */ 822 mutex_enter(&uobj->vmobjlock); 823 /* locked: maps(read), amap(if there), uobj */ 824 error = uobj->pgops->pgo_fault(&ufi, 825 flt.startva, pages, flt.npages, 826 flt.centeridx, flt.access_type, 827 PGO_LOCKED|PGO_SYNCIO); 828 829 /* 830 * locked: nothing, pgo_fault has unlocked 831 * everything 832 */ 833 834 /* 835 * object fault routine responsible for 836 * pmap_update(). 837 */ 838 } else { 839 error = uvm_fault_lower(&ufi, &flt, pages); 840 } 841 } 842 } 843 844 if (flt.anon_spare != NULL) { 845 flt.anon_spare->an_ref--; 846 uvm_anfree(flt.anon_spare); 847 } 848 return error; 849 } 850 851 /* 852 * uvm_fault_check: check prot, handle needs-copy, etc. 853 * 854 * 1. lookup entry. 855 * 2. check protection. 856 * 3. adjust fault condition (mainly for simulated fault). 857 * 4. handle needs-copy (lazy amap copy). 858 * 5. establish range of interest for neighbor fault (aka pre-fault). 859 * 6. look up anons (if amap exists). 860 * 7. flush pages (if MADV_SEQUENTIAL) 861 * 862 * => called with nothing locked. 863 * => if we fail (result != 0) we unlock everything. 864 * => initialize/adjust many members of flt. 865 */ 866 867 static int 868 uvm_fault_check( 869 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 870 struct vm_anon ***ranons, bool maxprot) 871 { 872 struct vm_amap *amap; 873 struct uvm_object *uobj; 874 vm_prot_t check_prot; 875 int nback, nforw; 876 UVMHIST_FUNC("uvm_fault_check"); UVMHIST_CALLED(maphist); 877 878 /* 879 * lookup and lock the maps 880 */ 881 882 if (uvmfault_lookup(ufi, false) == false) { 883 UVMHIST_LOG(maphist, "<- no mapping @ 0x%x", ufi->orig_rvaddr, 884 0,0,0); 885 return EFAULT; 886 } 887 /* locked: maps(read) */ 888 889 #ifdef DIAGNOSTIC 890 if ((ufi->map->flags & VM_MAP_PAGEABLE) == 0) { 891 printf("Page fault on non-pageable map:\n"); 892 printf("ufi->map = %p\n", ufi->map); 893 printf("ufi->orig_map = %p\n", ufi->orig_map); 894 printf("ufi->orig_rvaddr = 0x%lx\n", (u_long) ufi->orig_rvaddr); 895 panic("uvm_fault: (ufi->map->flags & VM_MAP_PAGEABLE) == 0"); 896 } 897 #endif 898 899 /* 900 * check protection 901 */ 902 903 check_prot = maxprot ? 904 ufi->entry->max_protection : ufi->entry->protection; 905 if ((check_prot & flt->access_type) != flt->access_type) { 906 UVMHIST_LOG(maphist, 907 "<- protection failure (prot=0x%x, access=0x%x)", 908 ufi->entry->protection, flt->access_type, 0, 0); 909 uvmfault_unlockmaps(ufi, false); 910 return EACCES; 911 } 912 913 /* 914 * "enter_prot" is the protection we want to enter the page in at. 915 * for certain pages (e.g. copy-on-write pages) this protection can 916 * be more strict than ufi->entry->protection. "wired" means either 917 * the entry is wired or we are fault-wiring the pg. 918 */ 919 920 flt->enter_prot = ufi->entry->protection; 921 if (VM_MAPENT_ISWIRED(ufi->entry)) 922 flt->wire_mapping = true; 923 924 if (flt->wire_mapping) { 925 flt->access_type = flt->enter_prot; /* full access for wired */ 926 flt->cow_now = (check_prot & VM_PROT_WRITE) != 0; 927 } else { 928 flt->cow_now = (flt->access_type & VM_PROT_WRITE) != 0; 929 } 930 931 flt->promote = false; 932 933 /* 934 * handle "needs_copy" case. if we need to copy the amap we will 935 * have to drop our readlock and relock it with a write lock. (we 936 * need a write lock to change anything in a map entry [e.g. 937 * needs_copy]). 938 */ 939 940 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 941 if (flt->cow_now || (ufi->entry->object.uvm_obj == NULL)) { 942 KASSERT(!maxprot); 943 /* need to clear */ 944 UVMHIST_LOG(maphist, 945 " need to clear needs_copy and refault",0,0,0,0); 946 uvmfault_unlockmaps(ufi, false); 947 uvmfault_amapcopy(ufi); 948 uvmexp.fltamcopy++; 949 return ERESTART; 950 951 } else { 952 953 /* 954 * ensure that we pmap_enter page R/O since 955 * needs_copy is still true 956 */ 957 958 flt->enter_prot &= ~VM_PROT_WRITE; 959 } 960 } 961 962 /* 963 * identify the players 964 */ 965 966 amap = ufi->entry->aref.ar_amap; /* upper layer */ 967 uobj = ufi->entry->object.uvm_obj; /* lower layer */ 968 969 /* 970 * check for a case 0 fault. if nothing backing the entry then 971 * error now. 972 */ 973 974 if (amap == NULL && uobj == NULL) { 975 uvmfault_unlockmaps(ufi, false); 976 UVMHIST_LOG(maphist,"<- no backing store, no overlay",0,0,0,0); 977 return EFAULT; 978 } 979 980 /* 981 * establish range of interest based on advice from mapper 982 * and then clip to fit map entry. note that we only want 983 * to do this the first time through the fault. if we 984 * ReFault we will disable this by setting "narrow" to true. 985 */ 986 987 if (flt->narrow == false) { 988 989 /* wide fault (!narrow) */ 990 KASSERT(uvmadvice[ufi->entry->advice].advice == 991 ufi->entry->advice); 992 nback = MIN(uvmadvice[ufi->entry->advice].nback, 993 (ufi->orig_rvaddr - ufi->entry->start) >> PAGE_SHIFT); 994 flt->startva = ufi->orig_rvaddr - (nback << PAGE_SHIFT); 995 /* 996 * note: "-1" because we don't want to count the 997 * faulting page as forw 998 */ 999 nforw = MIN(uvmadvice[ufi->entry->advice].nforw, 1000 ((ufi->entry->end - ufi->orig_rvaddr) >> 1001 PAGE_SHIFT) - 1); 1002 flt->npages = nback + nforw + 1; 1003 flt->centeridx = nback; 1004 1005 flt->narrow = true; /* ensure only once per-fault */ 1006 1007 } else { 1008 1009 /* narrow fault! */ 1010 nback = nforw = 0; 1011 flt->startva = ufi->orig_rvaddr; 1012 flt->npages = 1; 1013 flt->centeridx = 0; 1014 1015 } 1016 /* offset from entry's start to pgs' start */ 1017 const voff_t eoff = flt->startva - ufi->entry->start; 1018 1019 /* locked: maps(read) */ 1020 UVMHIST_LOG(maphist, " narrow=%d, back=%d, forw=%d, startva=0x%x", 1021 flt->narrow, nback, nforw, flt->startva); 1022 UVMHIST_LOG(maphist, " entry=0x%x, amap=0x%x, obj=0x%x", ufi->entry, 1023 amap, uobj, 0); 1024 1025 /* 1026 * if we've got an amap, lock it and extract current anons. 1027 */ 1028 1029 if (amap) { 1030 amap_lock(amap); 1031 amap_lookups(&ufi->entry->aref, eoff, *ranons, flt->npages); 1032 } else { 1033 *ranons = NULL; /* to be safe */ 1034 } 1035 1036 /* locked: maps(read), amap(if there) */ 1037 KASSERT(amap == NULL || mutex_owned(&amap->am_l)); 1038 1039 /* 1040 * for MADV_SEQUENTIAL mappings we want to deactivate the back pages 1041 * now and then forget about them (for the rest of the fault). 1042 */ 1043 1044 if (ufi->entry->advice == MADV_SEQUENTIAL && nback != 0) { 1045 1046 UVMHIST_LOG(maphist, " MADV_SEQUENTIAL: flushing backpages", 1047 0,0,0,0); 1048 /* flush back-page anons? */ 1049 if (amap) 1050 uvmfault_anonflush(*ranons, nback); 1051 1052 /* flush object? */ 1053 if (uobj) { 1054 voff_t uoff; 1055 1056 uoff = ufi->entry->offset + eoff; 1057 mutex_enter(&uobj->vmobjlock); 1058 (void) (uobj->pgops->pgo_put)(uobj, uoff, uoff + 1059 (nback << PAGE_SHIFT), PGO_DEACTIVATE); 1060 } 1061 1062 /* now forget about the backpages */ 1063 if (amap) 1064 *ranons += nback; 1065 flt->startva += (nback << PAGE_SHIFT); 1066 flt->npages -= nback; 1067 flt->centeridx = 0; 1068 } 1069 /* 1070 * => startva is fixed 1071 * => npages is fixed 1072 */ 1073 KASSERT(flt->startva <= ufi->orig_rvaddr); 1074 KASSERT(ufi->orig_rvaddr + ufi->orig_size <= 1075 flt->startva + (flt->npages << PAGE_SHIFT)); 1076 return 0; 1077 } 1078 1079 /* 1080 * uvm_fault_upper_lookup: look up existing h/w mapping and amap. 1081 * 1082 * iterate range of interest: 1083 * 1. check if h/w mapping exists. if yes, we don't care 1084 * 2. check if anon exists. if not, page is lower. 1085 * 3. if anon exists, enter h/w mapping for neighbors. 1086 * 1087 * => called with amap locked (if exists). 1088 */ 1089 1090 static int 1091 uvm_fault_upper_lookup( 1092 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1093 struct vm_anon **anons, struct vm_page **pages) 1094 { 1095 struct vm_amap *amap = ufi->entry->aref.ar_amap; 1096 int lcv; 1097 vaddr_t currva; 1098 bool shadowed; 1099 UVMHIST_FUNC("uvm_fault_upper_lookup"); UVMHIST_CALLED(maphist); 1100 1101 /* locked: maps(read), amap(if there) */ 1102 KASSERT(amap == NULL || mutex_owned(&amap->am_l)); 1103 1104 /* 1105 * map in the backpages and frontpages we found in the amap in hopes 1106 * of preventing future faults. we also init the pages[] array as 1107 * we go. 1108 */ 1109 1110 currva = flt->startva; 1111 shadowed = false; 1112 for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { 1113 /* 1114 * don't play with VAs that are already mapped 1115 * (except for center) 1116 */ 1117 if (lcv != flt->centeridx && 1118 pmap_extract(ufi->orig_map->pmap, currva, NULL)) { 1119 pages[lcv] = PGO_DONTCARE; 1120 continue; 1121 } 1122 1123 /* 1124 * unmapped or center page. check if any anon at this level. 1125 */ 1126 if (amap == NULL || anons[lcv] == NULL) { 1127 pages[lcv] = NULL; 1128 continue; 1129 } 1130 1131 /* 1132 * check for present page and map if possible. re-activate it. 1133 */ 1134 1135 pages[lcv] = PGO_DONTCARE; 1136 if (lcv == flt->centeridx) { /* save center for later! */ 1137 shadowed = true; 1138 } else { 1139 struct vm_anon *anon = anons[lcv]; 1140 1141 mutex_enter(&anon->an_lock); 1142 struct vm_page *pg = anon->an_page; 1143 1144 /* ignore loaned and busy pages */ 1145 if (pg != NULL && pg->loan_count == 0 && 1146 (pg->flags & PG_BUSY) == 0) 1147 uvm_fault_upper_neighbor(ufi, flt, currva, 1148 pg, anon->an_ref > 1); 1149 mutex_exit(&anon->an_lock); 1150 } 1151 } 1152 1153 /* locked: maps(read), amap(if there) */ 1154 KASSERT(amap == NULL || mutex_owned(&amap->am_l)); 1155 /* (shadowed == true) if there is an anon at the faulting address */ 1156 UVMHIST_LOG(maphist, " shadowed=%d, will_get=%d", shadowed, 1157 (ufi->entry->object.uvm_obj && shadowed != false),0,0); 1158 1159 /* 1160 * note that if we are really short of RAM we could sleep in the above 1161 * call to pmap_enter with everything locked. bad? 1162 * 1163 * XXX Actually, that is bad; pmap_enter() should just fail in that 1164 * XXX case. --thorpej 1165 */ 1166 1167 return 0; 1168 } 1169 1170 /* 1171 * uvm_fault_upper_neighbor: enter single lower neighbor page. 1172 * 1173 * => called with amap and anon locked. 1174 */ 1175 1176 static void 1177 uvm_fault_upper_neighbor( 1178 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1179 vaddr_t currva, struct vm_page *pg, bool readonly) 1180 { 1181 UVMHIST_FUNC("uvm_fault_upper_neighbor"); UVMHIST_CALLED(maphist); 1182 1183 /* locked: amap, anon */ 1184 1185 mutex_enter(&uvm_pageqlock); 1186 uvm_pageenqueue(pg); 1187 mutex_exit(&uvm_pageqlock); 1188 UVMHIST_LOG(maphist, 1189 " MAPPING: n anon: pm=0x%x, va=0x%x, pg=0x%x", 1190 ufi->orig_map->pmap, currva, pg, 0); 1191 uvmexp.fltnamap++; 1192 1193 /* 1194 * Since this page isn't the page that's actually faulting, 1195 * ignore pmap_enter() failures; it's not critical that we 1196 * enter these right now. 1197 */ 1198 1199 (void) pmap_enter(ufi->orig_map->pmap, currva, 1200 VM_PAGE_TO_PHYS(pg), 1201 readonly ? (flt->enter_prot & ~VM_PROT_WRITE) : 1202 flt->enter_prot, 1203 PMAP_CANFAIL | (flt->wire_mapping ? PMAP_WIRED : 0)); 1204 1205 pmap_update(ufi->orig_map->pmap); 1206 } 1207 1208 /* 1209 * uvm_fault_upper: handle upper fault. 1210 * 1211 * 1. acquire anon lock. 1212 * 2. get anon. let uvmfault_anonget do the dirty work. 1213 * 3. handle loan. 1214 * 4. dispatch direct or promote handlers. 1215 */ 1216 1217 static int 1218 uvm_fault_upper( 1219 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1220 struct vm_anon **anons) 1221 { 1222 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1223 struct vm_anon * const anon = anons[flt->centeridx]; 1224 struct uvm_object *uobj; 1225 int error; 1226 UVMHIST_FUNC("uvm_fault_upper"); UVMHIST_CALLED(maphist); 1227 1228 /* locked: maps(read), amap */ 1229 KASSERT(mutex_owned(&amap->am_l)); 1230 1231 /* 1232 * handle case 1: fault on an anon in our amap 1233 */ 1234 1235 UVMHIST_LOG(maphist, " case 1 fault: anon=0x%x", anon, 0,0,0); 1236 mutex_enter(&anon->an_lock); 1237 1238 /* locked: maps(read), amap, anon */ 1239 KASSERT(mutex_owned(&amap->am_l)); 1240 KASSERT(mutex_owned(&anon->an_lock)); 1241 1242 /* 1243 * no matter if we have case 1A or case 1B we are going to need to 1244 * have the anon's memory resident. ensure that now. 1245 */ 1246 1247 /* 1248 * let uvmfault_anonget do the dirty work. 1249 * if it fails (!OK) it will unlock everything for us. 1250 * if it succeeds, locks are still valid and locked. 1251 * also, if it is OK, then the anon's page is on the queues. 1252 * if the page is on loan from a uvm_object, then anonget will 1253 * lock that object for us if it does not fail. 1254 */ 1255 1256 error = uvmfault_anonget(ufi, amap, anon); 1257 switch (error) { 1258 case 0: 1259 break; 1260 1261 case ERESTART: 1262 return ERESTART; 1263 1264 case EAGAIN: 1265 kpause("fltagain1", false, hz/2, NULL); 1266 return ERESTART; 1267 1268 default: 1269 return error; 1270 } 1271 1272 /* 1273 * uobj is non null if the page is on loan from an object (i.e. uobj) 1274 */ 1275 1276 uobj = anon->an_page->uobject; /* locked by anonget if !NULL */ 1277 1278 /* locked: maps(read), amap, anon, uobj(if one) */ 1279 KASSERT(mutex_owned(&amap->am_l)); 1280 KASSERT(mutex_owned(&anon->an_lock)); 1281 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock)); 1282 1283 /* 1284 * special handling for loaned pages 1285 */ 1286 1287 if (anon->an_page->loan_count) { 1288 error = uvm_fault_upper_loan(ufi, flt, anon, &uobj); 1289 if (error != 0) 1290 return error; 1291 } 1292 1293 /* 1294 * if we are case 1B then we will need to allocate a new blank 1295 * anon to transfer the data into. note that we have a lock 1296 * on anon, so no one can busy or release the page until we are done. 1297 * also note that the ref count can't drop to zero here because 1298 * it is > 1 and we are only dropping one ref. 1299 * 1300 * in the (hopefully very rare) case that we are out of RAM we 1301 * will unlock, wait for more RAM, and refault. 1302 * 1303 * if we are out of anon VM we kill the process (XXX: could wait?). 1304 */ 1305 1306 if (flt->cow_now && anon->an_ref > 1) { 1307 flt->promote = true; 1308 error = uvm_fault_upper_promote(ufi, flt, uobj, anon); 1309 } else { 1310 error = uvm_fault_upper_direct(ufi, flt, uobj, anon); 1311 } 1312 return error; 1313 } 1314 1315 /* 1316 * uvm_fault_upper_loan: handle loaned upper page. 1317 * 1318 * 1. if not cow'ing now, simply adjust flt->enter_prot. 1319 * 2. if cow'ing now, and if ref count is 1, break loan. 1320 */ 1321 1322 static int 1323 uvm_fault_upper_loan( 1324 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1325 struct vm_anon *anon, struct uvm_object **ruobj) 1326 { 1327 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1328 int error = 0; 1329 UVMHIST_FUNC("uvm_fault_upper_loan"); UVMHIST_CALLED(maphist); 1330 1331 if (!flt->cow_now) { 1332 1333 /* 1334 * for read faults on loaned pages we just cap the 1335 * protection at read-only. 1336 */ 1337 1338 flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; 1339 1340 } else { 1341 /* 1342 * note that we can't allow writes into a loaned page! 1343 * 1344 * if we have a write fault on a loaned page in an 1345 * anon then we need to look at the anon's ref count. 1346 * if it is greater than one then we are going to do 1347 * a normal copy-on-write fault into a new anon (this 1348 * is not a problem). however, if the reference count 1349 * is one (a case where we would normally allow a 1350 * write directly to the page) then we need to kill 1351 * the loan before we continue. 1352 */ 1353 1354 /* >1 case is already ok */ 1355 if (anon->an_ref == 1) { 1356 error = uvm_loanbreak_anon(anon, *ruobj); 1357 if (error != 0) { 1358 uvmfault_unlockall(ufi, amap, *ruobj, anon); 1359 uvm_wait("flt_noram2"); 1360 return ERESTART; 1361 } 1362 /* if we were a loan reciever uobj is gone */ 1363 if (*ruobj) 1364 *ruobj = NULL; 1365 } 1366 } 1367 return error; 1368 } 1369 1370 /* 1371 * uvm_fault_upper_promote: promote upper page. 1372 * 1373 * 1. call uvmfault_promote. 1374 * 2. enqueue page. 1375 * 3. deref. 1376 * 4. pass page to uvm_fault_upper_enter. 1377 */ 1378 1379 static int 1380 uvm_fault_upper_promote( 1381 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1382 struct uvm_object *uobj, struct vm_anon *anon) 1383 { 1384 struct vm_anon * const oanon = anon; 1385 struct vm_page *pg; 1386 int error; 1387 UVMHIST_FUNC("uvm_fault_upper_promote"); UVMHIST_CALLED(maphist); 1388 1389 UVMHIST_LOG(maphist, " case 1B: COW fault",0,0,0,0); 1390 uvmexp.flt_acow++; 1391 1392 error = uvmfault_promote(ufi, oanon, PGO_DONTCARE, &anon, 1393 &flt->anon_spare); 1394 switch (error) { 1395 case 0: 1396 break; 1397 case ERESTART: 1398 return ERESTART; 1399 default: 1400 return error; 1401 } 1402 1403 pg = anon->an_page; 1404 mutex_enter(&uvm_pageqlock); 1405 uvm_pageactivate(pg); 1406 mutex_exit(&uvm_pageqlock); 1407 pg->flags &= ~(PG_BUSY|PG_FAKE); 1408 UVM_PAGE_OWN(pg, NULL); 1409 1410 /* deref: can not drop to zero here by defn! */ 1411 oanon->an_ref--; 1412 1413 /* 1414 * note: oanon is still locked, as is the new anon. we 1415 * need to check for this later when we unlock oanon; if 1416 * oanon != anon, we'll have to unlock anon, too. 1417 */ 1418 1419 return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon); 1420 } 1421 1422 /* 1423 * uvm_fault_upper_direct: handle direct fault. 1424 */ 1425 1426 static int 1427 uvm_fault_upper_direct( 1428 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1429 struct uvm_object *uobj, struct vm_anon *anon) 1430 { 1431 struct vm_anon * const oanon = anon; 1432 struct vm_page *pg; 1433 UVMHIST_FUNC("uvm_fault_upper_direct"); UVMHIST_CALLED(maphist); 1434 1435 uvmexp.flt_anon++; 1436 pg = anon->an_page; 1437 if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */ 1438 flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; 1439 1440 return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon); 1441 } 1442 1443 /* 1444 * uvm_fault_upper_enter: enter h/w mapping of upper page. 1445 */ 1446 1447 static int 1448 uvm_fault_upper_enter( 1449 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1450 struct uvm_object *uobj, struct vm_anon *anon, struct vm_page *pg, 1451 struct vm_anon *oanon) 1452 { 1453 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1454 UVMHIST_FUNC("uvm_fault_upper_enter"); UVMHIST_CALLED(maphist); 1455 1456 /* locked: maps(read), amap, oanon, anon(if different from oanon) */ 1457 KASSERT(mutex_owned(&amap->am_l)); 1458 KASSERT(mutex_owned(&anon->an_lock)); 1459 KASSERT(mutex_owned(&oanon->an_lock)); 1460 1461 /* 1462 * now map the page in. 1463 */ 1464 1465 UVMHIST_LOG(maphist, 1466 " MAPPING: anon: pm=0x%x, va=0x%x, pg=0x%x, promote=%d", 1467 ufi->orig_map->pmap, ufi->orig_rvaddr, pg, flt->promote); 1468 if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr, 1469 VM_PAGE_TO_PHYS(pg), 1470 flt->enter_prot, flt->access_type | PMAP_CANFAIL | 1471 (flt->wire_mapping ? PMAP_WIRED : 0)) != 0) { 1472 1473 /* 1474 * No need to undo what we did; we can simply think of 1475 * this as the pmap throwing away the mapping information. 1476 * 1477 * We do, however, have to go through the ReFault path, 1478 * as the map may change while we're asleep. 1479 */ 1480 1481 if (anon != oanon) 1482 mutex_exit(&anon->an_lock); 1483 uvmfault_unlockall(ufi, amap, uobj, oanon); 1484 if (!uvm_reclaimable()) { 1485 UVMHIST_LOG(maphist, 1486 "<- failed. out of VM",0,0,0,0); 1487 /* XXX instrumentation */ 1488 return ENOMEM; 1489 } 1490 /* XXX instrumentation */ 1491 uvm_wait("flt_pmfail1"); 1492 return ERESTART; 1493 } 1494 1495 uvm_fault_upper_done(ufi, flt, anon, pg); 1496 1497 /* 1498 * done case 1! finish up by unlocking everything and returning success 1499 */ 1500 1501 if (anon != oanon) { 1502 mutex_exit(&anon->an_lock); 1503 } 1504 pmap_update(ufi->orig_map->pmap); 1505 uvmfault_unlockall(ufi, amap, uobj, oanon); 1506 return 0; 1507 } 1508 1509 /* 1510 * uvm_fault_upper_done: queue upper center page. 1511 */ 1512 1513 static void 1514 uvm_fault_upper_done( 1515 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1516 struct vm_anon *anon, struct vm_page *pg) 1517 { 1518 const bool wire_paging = flt->wire_paging; 1519 1520 UVMHIST_FUNC("uvm_fault_upper_done"); UVMHIST_CALLED(maphist); 1521 1522 /* 1523 * ... update the page queues. 1524 */ 1525 1526 mutex_enter(&uvm_pageqlock); 1527 if (wire_paging) { 1528 uvm_pagewire(pg); 1529 1530 /* 1531 * since the now-wired page cannot be paged out, 1532 * release its swap resources for others to use. 1533 * since an anon with no swap cannot be PG_CLEAN, 1534 * clear its clean flag now. 1535 */ 1536 1537 pg->flags &= ~(PG_CLEAN); 1538 1539 } else { 1540 uvm_pageactivate(pg); 1541 } 1542 mutex_exit(&uvm_pageqlock); 1543 1544 if (wire_paging) { 1545 uvm_anon_dropswap(anon); 1546 } 1547 } 1548 1549 /* 1550 * uvm_fault_lower: handle lower fault. 1551 * 1552 * 1. check uobj 1553 * 1.1. if null, ZFOD. 1554 * 1.2. if not null, look up unnmapped neighbor pages. 1555 * 2. for center page, check if promote. 1556 * 2.1. ZFOD always needs promotion. 1557 * 2.2. other uobjs, when entry is marked COW (usually MAP_PRIVATE vnode). 1558 * 3. if uobj is not ZFOD and page is not found, do i/o. 1559 * 4. dispatch either direct / promote fault. 1560 */ 1561 1562 static int 1563 uvm_fault_lower( 1564 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1565 struct vm_page **pages) 1566 { 1567 #ifdef DIAGNOSTIC 1568 struct vm_amap *amap = ufi->entry->aref.ar_amap; 1569 #endif 1570 struct uvm_object *uobj = ufi->entry->object.uvm_obj; 1571 struct vm_page *uobjpage; 1572 int error; 1573 UVMHIST_FUNC("uvm_fault_lower"); UVMHIST_CALLED(maphist); 1574 1575 /* locked: maps(read), amap(if there), uobj(if !null) */ 1576 1577 /* 1578 * now, if the desired page is not shadowed by the amap and we have 1579 * a backing object that does not have a special fault routine, then 1580 * we ask (with pgo_get) the object for resident pages that we care 1581 * about and attempt to map them in. we do not let pgo_get block 1582 * (PGO_LOCKED). 1583 */ 1584 1585 if (uobj == NULL) { 1586 /* zero fill; don't care neighbor pages */ 1587 uobjpage = NULL; 1588 } else { 1589 uvm_fault_lower_lookup(ufi, flt, pages); 1590 uobjpage = pages[flt->centeridx]; 1591 } 1592 1593 /* 1594 * note that at this point we are done with any front or back pages. 1595 * we are now going to focus on the center page (i.e. the one we've 1596 * faulted on). if we have faulted on the upper (anon) layer 1597 * [i.e. case 1], then the anon we want is anons[centeridx] (we have 1598 * not touched it yet). if we have faulted on the bottom (uobj) 1599 * layer [i.e. case 2] and the page was both present and available, 1600 * then we've got a pointer to it as "uobjpage" and we've already 1601 * made it BUSY. 1602 */ 1603 1604 /* 1605 * locked: 1606 * maps(read), amap(if there), uobj(if !null), uobjpage(if !null) 1607 */ 1608 KASSERT(amap == NULL || mutex_owned(&amap->am_l)); 1609 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock)); 1610 KASSERT(uobjpage == NULL || (uobjpage->flags & PG_BUSY) != 0); 1611 1612 /* 1613 * note that uobjpage can not be PGO_DONTCARE at this point. we now 1614 * set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we 1615 * have a backing object, check and see if we are going to promote 1616 * the data up to an anon during the fault. 1617 */ 1618 1619 if (uobj == NULL) { 1620 uobjpage = PGO_DONTCARE; 1621 flt->promote = true; /* always need anon here */ 1622 } else { 1623 KASSERT(uobjpage != PGO_DONTCARE); 1624 flt->promote = flt->cow_now && UVM_ET_ISCOPYONWRITE(ufi->entry); 1625 } 1626 UVMHIST_LOG(maphist, " case 2 fault: promote=%d, zfill=%d", 1627 flt->promote, (uobj == NULL), 0,0); 1628 1629 /* 1630 * if uobjpage is not null then we do not need to do I/O to get the 1631 * uobjpage. 1632 * 1633 * if uobjpage is null, then we need to unlock and ask the pager to 1634 * get the data for us. once we have the data, we need to reverify 1635 * the state the world. we are currently not holding any resources. 1636 */ 1637 1638 if (uobjpage) { 1639 /* update rusage counters */ 1640 curlwp->l_ru.ru_minflt++; 1641 } else { 1642 error = uvm_fault_lower_io(ufi, flt, &uobj, &uobjpage); 1643 if (error != 0) 1644 return error; 1645 } 1646 1647 /* 1648 * locked: 1649 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj) 1650 */ 1651 KASSERT(amap == NULL || mutex_owned(&amap->am_l)); 1652 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock)); 1653 KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0); 1654 1655 /* 1656 * notes: 1657 * - at this point uobjpage can not be NULL 1658 * - at this point uobjpage can not be PG_RELEASED (since we checked 1659 * for it above) 1660 * - at this point uobjpage could be PG_WANTED (handle later) 1661 */ 1662 1663 KASSERT(uobjpage != NULL); 1664 KASSERT(uobj == NULL || uobj == uobjpage->uobject); 1665 KASSERT(uobj == NULL || !UVM_OBJ_IS_CLEAN(uobjpage->uobject) || 1666 (uobjpage->flags & PG_CLEAN) != 0); 1667 1668 if (!flt->promote) { 1669 error = uvm_fault_lower_direct(ufi, flt, uobj, uobjpage); 1670 } else { 1671 error = uvm_fault_lower_promote(ufi, flt, uobj, uobjpage); 1672 } 1673 return error; 1674 } 1675 1676 /* 1677 * uvm_fault_lower_lookup: look up on-memory uobj pages. 1678 * 1679 * 1. get on-memory pages. 1680 * 2. if failed, give up (get only center page later). 1681 * 3. if succeeded, enter h/w mapping of neighbor pages. 1682 */ 1683 1684 static void 1685 uvm_fault_lower_lookup( 1686 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1687 struct vm_page **pages) 1688 { 1689 struct uvm_object *uobj = ufi->entry->object.uvm_obj; 1690 int lcv, gotpages; 1691 vaddr_t currva; 1692 UVMHIST_FUNC("uvm_fault_lower_lookup"); UVMHIST_CALLED(maphist); 1693 1694 mutex_enter(&uobj->vmobjlock); 1695 /* locked: maps(read), amap(if there), uobj */ 1696 /* 1697 * the following call to pgo_get does _not_ change locking state 1698 */ 1699 1700 uvmexp.fltlget++; 1701 gotpages = flt->npages; 1702 (void) uobj->pgops->pgo_get(uobj, 1703 ufi->entry->offset + flt->startva - ufi->entry->start, 1704 pages, &gotpages, flt->centeridx, 1705 flt->access_type & MASK(ufi->entry), ufi->entry->advice, PGO_LOCKED); 1706 1707 /* 1708 * check for pages to map, if we got any 1709 */ 1710 1711 if (gotpages == 0) { 1712 pages[flt->centeridx] = NULL; 1713 return; 1714 } 1715 1716 currva = flt->startva; 1717 for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { 1718 struct vm_page *curpg; 1719 1720 curpg = pages[lcv]; 1721 if (curpg == NULL || curpg == PGO_DONTCARE) { 1722 continue; 1723 } 1724 KASSERT(curpg->uobject == uobj); 1725 1726 /* 1727 * if center page is resident and not PG_BUSY|PG_RELEASED 1728 * then pgo_get made it PG_BUSY for us and gave us a handle 1729 * to it. 1730 */ 1731 1732 if (lcv == flt->centeridx) { 1733 UVMHIST_LOG(maphist, " got uobjpage " 1734 "(0x%x) with locked get", 1735 curpg, 0,0,0); 1736 } else { 1737 bool readonly = (curpg->flags & PG_RDONLY) 1738 || (curpg->loan_count > 0) 1739 || UVM_OBJ_NEEDS_WRITEFAULT(curpg->uobject); 1740 1741 uvm_fault_lower_neighbor(ufi, flt, 1742 currva, curpg, readonly); 1743 } 1744 } 1745 pmap_update(ufi->orig_map->pmap); 1746 } 1747 1748 /* 1749 * uvm_fault_lower_neighbor: enter h/w mapping of lower neighbor page. 1750 */ 1751 1752 static void 1753 uvm_fault_lower_neighbor( 1754 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1755 vaddr_t currva, struct vm_page *pg, bool readonly) 1756 { 1757 UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); 1758 1759 /* locked: maps(read), amap(if there), uobj */ 1760 1761 /* 1762 * calling pgo_get with PGO_LOCKED returns us pages which 1763 * are neither busy nor released, so we don't need to check 1764 * for this. we can just directly enter the pages. 1765 */ 1766 1767 mutex_enter(&uvm_pageqlock); 1768 uvm_pageenqueue(pg); 1769 mutex_exit(&uvm_pageqlock); 1770 UVMHIST_LOG(maphist, 1771 " MAPPING: n obj: pm=0x%x, va=0x%x, pg=0x%x", 1772 ufi->orig_map->pmap, currva, pg, 0); 1773 uvmexp.fltnomap++; 1774 1775 /* 1776 * Since this page isn't the page that's actually faulting, 1777 * ignore pmap_enter() failures; it's not critical that we 1778 * enter these right now. 1779 * NOTE: page can't be PG_WANTED or PG_RELEASED because we've 1780 * held the lock the whole time we've had the handle. 1781 */ 1782 KASSERT((pg->flags & PG_PAGEOUT) == 0); 1783 KASSERT((pg->flags & PG_RELEASED) == 0); 1784 KASSERT((pg->flags & PG_WANTED) == 0); 1785 KASSERT(!UVM_OBJ_IS_CLEAN(pg->uobject) || 1786 (pg->flags & PG_CLEAN) != 0); 1787 pg->flags &= ~(PG_BUSY); 1788 UVM_PAGE_OWN(pg, NULL); 1789 1790 (void) pmap_enter(ufi->orig_map->pmap, currva, 1791 VM_PAGE_TO_PHYS(pg), 1792 readonly ? (flt->enter_prot & ~VM_PROT_WRITE) : 1793 flt->enter_prot & MASK(ufi->entry), 1794 PMAP_CANFAIL | (flt->wire_mapping ? PMAP_WIRED : 0)); 1795 } 1796 1797 /* 1798 * uvm_fault_lower_io: get lower page from backing store. 1799 * 1800 * 1. unlock everything, because i/o will block. 1801 * 2. call pgo_get. 1802 * 3. if failed, recover. 1803 * 4. if succeeded, relock everything and verify things. 1804 */ 1805 1806 static int 1807 uvm_fault_lower_io( 1808 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1809 struct uvm_object **ruobj, struct vm_page **ruobjpage) 1810 { 1811 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1812 struct uvm_object *uobj = *ruobj; 1813 struct vm_page *pg; 1814 bool locked; 1815 int gotpages; 1816 int error; 1817 voff_t uoff; 1818 UVMHIST_FUNC("uvm_fault_lower_io"); UVMHIST_CALLED(maphist); 1819 1820 /* update rusage counters */ 1821 curlwp->l_ru.ru_majflt++; 1822 1823 /* locked: maps(read), amap(if there), uobj */ 1824 uvmfault_unlockall(ufi, amap, NULL, NULL); 1825 /* locked: uobj */ 1826 1827 uvmexp.fltget++; 1828 gotpages = 1; 1829 pg = NULL; 1830 uoff = (ufi->orig_rvaddr - ufi->entry->start) + ufi->entry->offset; 1831 error = uobj->pgops->pgo_get(uobj, uoff, &pg, &gotpages, 1832 0, flt->access_type & MASK(ufi->entry), ufi->entry->advice, 1833 PGO_SYNCIO); 1834 /* locked: pg(if no error) */ 1835 1836 /* 1837 * recover from I/O 1838 */ 1839 1840 if (error) { 1841 if (error == EAGAIN) { 1842 UVMHIST_LOG(maphist, 1843 " pgo_get says TRY AGAIN!",0,0,0,0); 1844 kpause("fltagain2", false, hz/2, NULL); 1845 return ERESTART; 1846 } 1847 1848 #if 0 1849 KASSERT(error != ERESTART); 1850 #else 1851 /* XXXUEBS don't re-fault? */ 1852 if (error == ERESTART) 1853 error = EIO; 1854 #endif 1855 1856 UVMHIST_LOG(maphist, "<- pgo_get failed (code %d)", 1857 error, 0,0,0); 1858 return error; 1859 } 1860 1861 /* locked: pg */ 1862 1863 KASSERT((pg->flags & PG_BUSY) != 0); 1864 1865 mutex_enter(&uvm_pageqlock); 1866 uvm_pageactivate(pg); 1867 mutex_exit(&uvm_pageqlock); 1868 1869 /* 1870 * re-verify the state of the world by first trying to relock 1871 * the maps. always relock the object. 1872 */ 1873 1874 locked = uvmfault_relock(ufi); 1875 if (locked && amap) 1876 amap_lock(amap); 1877 1878 /* might be changed */ 1879 uobj = pg->uobject; 1880 1881 mutex_enter(&uobj->vmobjlock); 1882 1883 /* locked(locked): maps(read), amap(if !null), uobj, pg */ 1884 /* locked(!locked): uobj, pg */ 1885 1886 /* 1887 * verify that the page has not be released and re-verify 1888 * that amap slot is still free. if there is a problem, 1889 * we unlock and clean up. 1890 */ 1891 1892 if ((pg->flags & PG_RELEASED) != 0 || 1893 (locked && amap && amap_lookup(&ufi->entry->aref, 1894 ufi->orig_rvaddr - ufi->entry->start))) { 1895 if (locked) 1896 uvmfault_unlockall(ufi, amap, NULL, NULL); 1897 locked = false; 1898 } 1899 1900 /* 1901 * didn't get the lock? release the page and retry. 1902 */ 1903 1904 if (locked == false) { 1905 UVMHIST_LOG(maphist, 1906 " wasn't able to relock after fault: retry", 1907 0,0,0,0); 1908 if (pg->flags & PG_WANTED) { 1909 wakeup(pg); 1910 } 1911 if (pg->flags & PG_RELEASED) { 1912 uvmexp.fltpgrele++; 1913 uvm_pagefree(pg); 1914 mutex_exit(&uobj->vmobjlock); 1915 return ERESTART; 1916 } 1917 pg->flags &= ~(PG_BUSY|PG_WANTED); 1918 UVM_PAGE_OWN(pg, NULL); 1919 mutex_exit(&uobj->vmobjlock); 1920 return ERESTART; 1921 } 1922 1923 /* 1924 * we have the data in pg which is busy and 1925 * not released. we are holding object lock (so the page 1926 * can't be released on us). 1927 */ 1928 1929 /* locked: maps(read), amap(if !null), uobj, pg */ 1930 1931 *ruobj = uobj; 1932 *ruobjpage = pg; 1933 return 0; 1934 } 1935 1936 /* 1937 * uvm_fault_lower_direct: fault lower center page 1938 * 1939 * 1. adjust flt->enter_prot. 1940 * 2. if page is loaned, resolve. 1941 */ 1942 1943 int 1944 uvm_fault_lower_direct( 1945 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1946 struct uvm_object *uobj, struct vm_page *uobjpage) 1947 { 1948 struct vm_page *pg; 1949 UVMHIST_FUNC("uvm_fault_lower_direct"); UVMHIST_CALLED(maphist); 1950 1951 /* 1952 * we are not promoting. if the mapping is COW ensure that we 1953 * don't give more access than we should (e.g. when doing a read 1954 * fault on a COPYONWRITE mapping we want to map the COW page in 1955 * R/O even though the entry protection could be R/W). 1956 * 1957 * set "pg" to the page we want to map in (uobjpage, usually) 1958 */ 1959 1960 uvmexp.flt_obj++; 1961 if (UVM_ET_ISCOPYONWRITE(ufi->entry) || 1962 UVM_OBJ_NEEDS_WRITEFAULT(uobjpage->uobject)) 1963 flt->enter_prot &= ~VM_PROT_WRITE; 1964 pg = uobjpage; /* map in the actual object */ 1965 1966 KASSERT(uobjpage != PGO_DONTCARE); 1967 1968 /* 1969 * we are faulting directly on the page. be careful 1970 * about writing to loaned pages... 1971 */ 1972 1973 if (uobjpage->loan_count) { 1974 uvm_fault_lower_direct_loan(ufi, flt, uobj, &pg, &uobjpage); 1975 } 1976 KASSERT(pg == uobjpage); 1977 1978 return uvm_fault_lower_enter(ufi, flt, uobj, NULL, pg, uobjpage); 1979 } 1980 1981 /* 1982 * uvm_fault_lower_direct_loan: resolve loaned page. 1983 * 1984 * 1. if not cow'ing, adjust flt->enter_prot. 1985 * 2. if cow'ing, break loan. 1986 */ 1987 1988 static int 1989 uvm_fault_lower_direct_loan( 1990 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1991 struct uvm_object *uobj, struct vm_page **rpg, 1992 struct vm_page **ruobjpage) 1993 { 1994 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 1995 struct vm_page *pg; 1996 struct vm_page *uobjpage = *ruobjpage; 1997 UVMHIST_FUNC("uvm_fault_lower_direct_loan"); UVMHIST_CALLED(maphist); 1998 1999 if (!flt->cow_now) { 2000 /* read fault: cap the protection at readonly */ 2001 /* cap! */ 2002 flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; 2003 } else { 2004 /* write fault: must break the loan here */ 2005 2006 pg = uvm_loanbreak(uobjpage); 2007 if (pg == NULL) { 2008 2009 /* 2010 * drop ownership of page, it can't be released 2011 */ 2012 2013 if (uobjpage->flags & PG_WANTED) 2014 wakeup(uobjpage); 2015 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 2016 UVM_PAGE_OWN(uobjpage, NULL); 2017 2018 uvmfault_unlockall(ufi, amap, uobj, NULL); 2019 UVMHIST_LOG(maphist, 2020 " out of RAM breaking loan, waiting", 2021 0,0,0,0); 2022 uvmexp.fltnoram++; 2023 uvm_wait("flt_noram4"); 2024 return ERESTART; 2025 } 2026 *rpg = pg; 2027 *ruobjpage = pg; 2028 } 2029 return 0; 2030 } 2031 2032 /* 2033 * uvm_fault_lower_promote: promote lower page. 2034 * 2035 * 1. call uvmfault_promote. 2036 * 2. fill in data. 2037 * 3. if not ZFOD, dispose old page. 2038 */ 2039 2040 int 2041 uvm_fault_lower_promote( 2042 struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 2043 struct uvm_object *uobj, struct vm_page *uobjpage) 2044 { 2045 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 2046 struct vm_anon *anon; 2047 struct vm_page *pg; 2048 int error; 2049 UVMHIST_FUNC("uvm_fault_lower_promote"); UVMHIST_CALLED(maphist); 2050 2051 /* 2052 * if we are going to promote the data to an anon we 2053 * allocate a blank anon here and plug it into our amap. 2054 */ 2055 #if DIAGNOSTIC 2056 if (amap == NULL) 2057 panic("uvm_fault: want to promote data, but no anon"); 2058 #endif 2059 error = uvmfault_promote(ufi, NULL, uobjpage, 2060 &anon, &flt->anon_spare); 2061 switch (error) { 2062 case 0: 2063 break; 2064 case ERESTART: 2065 return ERESTART; 2066 default: 2067 return error; 2068 } 2069 2070 pg = anon->an_page; 2071 2072 /* 2073 * fill in the data 2074 */ 2075 2076 if (uobjpage != PGO_DONTCARE) { 2077 uvmexp.flt_prcopy++; 2078 2079 /* 2080 * promote to shared amap? make sure all sharing 2081 * procs see it 2082 */ 2083 2084 if ((amap_flags(amap) & AMAP_SHARED) != 0) { 2085 pmap_page_protect(uobjpage, VM_PROT_NONE); 2086 /* 2087 * XXX: PAGE MIGHT BE WIRED! 2088 */ 2089 } 2090 2091 /* 2092 * dispose of uobjpage. it can't be PG_RELEASED 2093 * since we still hold the object lock. 2094 * drop handle to uobj as well. 2095 */ 2096 2097 if (uobjpage->flags & PG_WANTED) 2098 /* still have the obj lock */ 2099 wakeup(uobjpage); 2100 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 2101 UVM_PAGE_OWN(uobjpage, NULL); 2102 mutex_exit(&uobj->vmobjlock); 2103 uobj = NULL; 2104 2105 UVMHIST_LOG(maphist, 2106 " promote uobjpage 0x%x to anon/page 0x%x/0x%x", 2107 uobjpage, anon, pg, 0); 2108 2109 } else { 2110 uvmexp.flt_przero++; 2111 2112 /* 2113 * Page is zero'd and marked dirty by 2114 * uvmfault_promote(). 2115 */ 2116 2117 UVMHIST_LOG(maphist," zero fill anon/page 0x%x/0%x", 2118 anon, pg, 0, 0); 2119 } 2120 2121 return uvm_fault_lower_enter(ufi, flt, uobj, anon, pg, uobjpage); 2122 } 2123 2124 /* 2125 * uvm_fault_lower_enter: enter h/w mapping of lower page. 2126 */ 2127 2128 int 2129 uvm_fault_lower_enter( 2130 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 2131 struct uvm_object *uobj, 2132 struct vm_anon *anon, struct vm_page *pg, struct vm_page *uobjpage) 2133 { 2134 struct vm_amap * const amap = ufi->entry->aref.ar_amap; 2135 int error; 2136 UVMHIST_FUNC("uvm_fault_lower_enter"); UVMHIST_CALLED(maphist); 2137 2138 /* 2139 * locked: 2140 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj), 2141 * anon(if !null), pg(if anon) 2142 * 2143 * note: pg is either the uobjpage or the new page in the new anon 2144 */ 2145 KASSERT(amap == NULL || mutex_owned(&amap->am_l)); 2146 KASSERT(uobj == NULL || mutex_owned(&uobj->vmobjlock)); 2147 KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0); 2148 KASSERT(anon == NULL || mutex_owned(&anon->an_lock)); 2149 KASSERT((pg->flags & PG_BUSY) != 0); 2150 2151 /* 2152 * all resources are present. we can now map it in and free our 2153 * resources. 2154 */ 2155 2156 UVMHIST_LOG(maphist, 2157 " MAPPING: case2: pm=0x%x, va=0x%x, pg=0x%x, promote=%d", 2158 ufi->orig_map->pmap, ufi->orig_rvaddr, pg, flt->promote); 2159 KASSERT((flt->access_type & VM_PROT_WRITE) == 0 || 2160 (pg->flags & PG_RDONLY) == 0); 2161 if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr, 2162 VM_PAGE_TO_PHYS(pg), 2163 (pg->flags & PG_RDONLY) != 0 ? 2164 flt->enter_prot & ~VM_PROT_WRITE : flt->enter_prot, 2165 flt->access_type | PMAP_CANFAIL | 2166 (flt->wire_mapping ? PMAP_WIRED : 0)) != 0) { 2167 2168 /* 2169 * No need to undo what we did; we can simply think of 2170 * this as the pmap throwing away the mapping information. 2171 * 2172 * We do, however, have to go through the ReFault path, 2173 * as the map may change while we're asleep. 2174 */ 2175 2176 if (pg->flags & PG_WANTED) 2177 wakeup(pg); 2178 2179 /* 2180 * note that pg can't be PG_RELEASED since we did not drop 2181 * the object lock since the last time we checked. 2182 */ 2183 KASSERT((pg->flags & PG_RELEASED) == 0); 2184 2185 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 2186 UVM_PAGE_OWN(pg, NULL); 2187 2188 uvmfault_unlockall(ufi, amap, uobj, anon); 2189 if (!uvm_reclaimable()) { 2190 UVMHIST_LOG(maphist, 2191 "<- failed. out of VM",0,0,0,0); 2192 /* XXX instrumentation */ 2193 error = ENOMEM; 2194 return error; 2195 } 2196 /* XXX instrumentation */ 2197 uvm_wait("flt_pmfail2"); 2198 return ERESTART; 2199 } 2200 2201 uvm_fault_lower_done(ufi, flt, uobj, pg); 2202 2203 /* 2204 * note that pg can't be PG_RELEASED since we did not drop the object 2205 * lock since the last time we checked. 2206 */ 2207 KASSERT((pg->flags & PG_RELEASED) == 0); 2208 if (pg->flags & PG_WANTED) 2209 wakeup(pg); 2210 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 2211 UVM_PAGE_OWN(pg, NULL); 2212 2213 pmap_update(ufi->orig_map->pmap); 2214 uvmfault_unlockall(ufi, amap, uobj, anon); 2215 2216 UVMHIST_LOG(maphist, "<- done (SUCCESS!)",0,0,0,0); 2217 return 0; 2218 } 2219 2220 /* 2221 * uvm_fault_lower_done: queue lower center page. 2222 */ 2223 2224 void 2225 uvm_fault_lower_done( 2226 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 2227 struct uvm_object *uobj, struct vm_page *pg) 2228 { 2229 bool dropswap = false; 2230 2231 UVMHIST_FUNC("uvm_fault_lower_done"); UVMHIST_CALLED(maphist); 2232 2233 mutex_enter(&uvm_pageqlock); 2234 if (flt->wire_paging) { 2235 uvm_pagewire(pg); 2236 if (pg->pqflags & PQ_AOBJ) { 2237 2238 /* 2239 * since the now-wired page cannot be paged out, 2240 * release its swap resources for others to use. 2241 * since an aobj page with no swap cannot be PG_CLEAN, 2242 * clear its clean flag now. 2243 */ 2244 2245 KASSERT(uobj != NULL); 2246 pg->flags &= ~(PG_CLEAN); 2247 dropswap = true; 2248 } 2249 } else { 2250 uvm_pageactivate(pg); 2251 } 2252 mutex_exit(&uvm_pageqlock); 2253 2254 if (dropswap) { 2255 uao_dropswap(uobj, pg->offset >> PAGE_SHIFT); 2256 } 2257 } 2258 2259 2260 /* 2261 * uvm_fault_wire: wire down a range of virtual addresses in a map. 2262 * 2263 * => map may be read-locked by caller, but MUST NOT be write-locked. 2264 * => if map is read-locked, any operations which may cause map to 2265 * be write-locked in uvm_fault() must be taken care of by 2266 * the caller. See uvm_map_pageable(). 2267 */ 2268 2269 int 2270 uvm_fault_wire(struct vm_map *map, vaddr_t start, vaddr_t end, 2271 vm_prot_t access_type, int maxprot) 2272 { 2273 vaddr_t va; 2274 int error; 2275 2276 /* 2277 * now fault it in a page at a time. if the fault fails then we have 2278 * to undo what we have done. note that in uvm_fault VM_PROT_NONE 2279 * is replaced with the max protection if fault_type is VM_FAULT_WIRE. 2280 */ 2281 2282 /* 2283 * XXX work around overflowing a vaddr_t. this prevents us from 2284 * wiring the last page in the address space, though. 2285 */ 2286 if (start > end) { 2287 return EFAULT; 2288 } 2289 2290 for (va = start; va < end; va += PAGE_SIZE) { 2291 error = uvm_fault_internal(map, va, access_type, 2292 (maxprot ? UVM_FAULT_MAXPROT : 0) | UVM_FAULT_WIRE); 2293 if (error) { 2294 if (va != start) { 2295 uvm_fault_unwire(map, start, va); 2296 } 2297 return error; 2298 } 2299 } 2300 return 0; 2301 } 2302 2303 /* 2304 * uvm_fault_unwire(): unwire range of virtual space. 2305 */ 2306 2307 void 2308 uvm_fault_unwire(struct vm_map *map, vaddr_t start, vaddr_t end) 2309 { 2310 vm_map_lock_read(map); 2311 uvm_fault_unwire_locked(map, start, end); 2312 vm_map_unlock_read(map); 2313 } 2314 2315 /* 2316 * uvm_fault_unwire_locked(): the guts of uvm_fault_unwire(). 2317 * 2318 * => map must be at least read-locked. 2319 */ 2320 2321 void 2322 uvm_fault_unwire_locked(struct vm_map *map, vaddr_t start, vaddr_t end) 2323 { 2324 struct vm_map_entry *entry; 2325 pmap_t pmap = vm_map_pmap(map); 2326 vaddr_t va; 2327 paddr_t pa; 2328 struct vm_page *pg; 2329 2330 KASSERT((map->flags & VM_MAP_INTRSAFE) == 0); 2331 2332 /* 2333 * we assume that the area we are unwiring has actually been wired 2334 * in the first place. this means that we should be able to extract 2335 * the PAs from the pmap. we also lock out the page daemon so that 2336 * we can call uvm_pageunwire. 2337 */ 2338 2339 mutex_enter(&uvm_pageqlock); 2340 2341 /* 2342 * find the beginning map entry for the region. 2343 */ 2344 2345 KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map)); 2346 if (uvm_map_lookup_entry(map, start, &entry) == false) 2347 panic("uvm_fault_unwire_locked: address not in map"); 2348 2349 for (va = start; va < end; va += PAGE_SIZE) { 2350 if (pmap_extract(pmap, va, &pa) == false) 2351 continue; 2352 2353 /* 2354 * find the map entry for the current address. 2355 */ 2356 2357 KASSERT(va >= entry->start); 2358 while (va >= entry->end) { 2359 KASSERT(entry->next != &map->header && 2360 entry->next->start <= entry->end); 2361 entry = entry->next; 2362 } 2363 2364 /* 2365 * if the entry is no longer wired, tell the pmap. 2366 */ 2367 2368 if (VM_MAPENT_ISWIRED(entry) == 0) 2369 pmap_unwire(pmap, va); 2370 2371 pg = PHYS_TO_VM_PAGE(pa); 2372 if (pg) 2373 uvm_pageunwire(pg); 2374 } 2375 2376 mutex_exit(&uvm_pageqlock); 2377 } 2378