1 /* $NetBSD: uvm_fault.c,v 1.67 2001/06/26 17:55:14 thorpej Exp $ */ 2 3 /* 4 * 5 * Copyright (c) 1997 Charles D. Cranor and Washington University. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Charles D. Cranor and 19 * Washington University. 20 * 4. The name of the author may not be used to endorse or promote products 21 * derived from this software without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 24 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 25 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 26 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 27 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 28 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 29 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 30 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 31 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 32 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 33 * 34 * from: Id: uvm_fault.c,v 1.1.2.23 1998/02/06 05:29:05 chs Exp 35 */ 36 37 #include "opt_uvmhist.h" 38 39 /* 40 * uvm_fault.c: fault handler 41 */ 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 #include <sys/kernel.h> 46 #include <sys/proc.h> 47 #include <sys/malloc.h> 48 #include <sys/mman.h> 49 #include <sys/user.h> 50 51 #include <uvm/uvm.h> 52 53 /* 54 * 55 * a word on page faults: 56 * 57 * types of page faults we handle: 58 * 59 * CASE 1: upper layer faults CASE 2: lower layer faults 60 * 61 * CASE 1A CASE 1B CASE 2A CASE 2B 62 * read/write1 write>1 read/write +-cow_write/zero 63 * | | | | 64 * +--|--+ +--|--+ +-----+ + | + | +-----+ 65 * amap | V | | ----------->new| | | | ^ | 66 * +-----+ +-----+ +-----+ + | + | +--|--+ 67 * | | | 68 * +-----+ +-----+ +--|--+ | +--|--+ 69 * uobj | d/c | | d/c | | V | +----| | 70 * +-----+ +-----+ +-----+ +-----+ 71 * 72 * d/c = don't care 73 * 74 * case [0]: layerless fault 75 * no amap or uobj is present. this is an error. 76 * 77 * case [1]: upper layer fault [anon active] 78 * 1A: [read] or [write with anon->an_ref == 1] 79 * I/O takes place in top level anon and uobj is not touched. 80 * 1B: [write with anon->an_ref > 1] 81 * new anon is alloc'd and data is copied off ["COW"] 82 * 83 * case [2]: lower layer fault [uobj] 84 * 2A: [read on non-NULL uobj] or [write to non-copy_on_write area] 85 * I/O takes place directly in object. 86 * 2B: [write to copy_on_write] or [read on NULL uobj] 87 * data is "promoted" from uobj to a new anon. 88 * if uobj is null, then we zero fill. 89 * 90 * we follow the standard UVM locking protocol ordering: 91 * 92 * MAPS => AMAP => UOBJ => ANON => PAGE QUEUES (PQ) 93 * we hold a PG_BUSY page if we unlock for I/O 94 * 95 * 96 * the code is structured as follows: 97 * 98 * - init the "IN" params in the ufi structure 99 * ReFault: 100 * - do lookups [locks maps], check protection, handle needs_copy 101 * - check for case 0 fault (error) 102 * - establish "range" of fault 103 * - if we have an amap lock it and extract the anons 104 * - if sequential advice deactivate pages behind us 105 * - at the same time check pmap for unmapped areas and anon for pages 106 * that we could map in (and do map it if found) 107 * - check object for resident pages that we could map in 108 * - if (case 2) goto Case2 109 * - >>> handle case 1 110 * - ensure source anon is resident in RAM 111 * - if case 1B alloc new anon and copy from source 112 * - map the correct page in 113 * Case2: 114 * - >>> handle case 2 115 * - ensure source page is resident (if uobj) 116 * - if case 2B alloc new anon and copy from source (could be zero 117 * fill if uobj == NULL) 118 * - map the correct page in 119 * - done! 120 * 121 * note on paging: 122 * if we have to do I/O we place a PG_BUSY page in the correct object, 123 * unlock everything, and do the I/O. when I/O is done we must reverify 124 * the state of the world before assuming that our data structures are 125 * valid. [because mappings could change while the map is unlocked] 126 * 127 * alternative 1: unbusy the page in question and restart the page fault 128 * from the top (ReFault). this is easy but does not take advantage 129 * of the information that we already have from our previous lookup, 130 * although it is possible that the "hints" in the vm_map will help here. 131 * 132 * alternative 2: the system already keeps track of a "version" number of 133 * a map. [i.e. every time you write-lock a map (e.g. to change a 134 * mapping) you bump the version number up by one...] so, we can save 135 * the version number of the map before we release the lock and start I/O. 136 * then when I/O is done we can relock and check the version numbers 137 * to see if anything changed. this might save us some over 1 because 138 * we don't have to unbusy the page and may be less compares(?). 139 * 140 * alternative 3: put in backpointers or a way to "hold" part of a map 141 * in place while I/O is in progress. this could be complex to 142 * implement (especially with structures like amap that can be referenced 143 * by multiple map entries, and figuring out what should wait could be 144 * complex as well...). 145 * 146 * given that we are not currently multiprocessor or multithreaded we might 147 * as well choose alternative 2 now. maybe alternative 3 would be useful 148 * in the future. XXX keep in mind for future consideration//rechecking. 149 */ 150 151 /* 152 * local data structures 153 */ 154 155 struct uvm_advice { 156 int advice; 157 int nback; 158 int nforw; 159 }; 160 161 /* 162 * page range array: 163 * note: index in array must match "advice" value 164 * XXX: borrowed numbers from freebsd. do they work well for us? 165 */ 166 167 static struct uvm_advice uvmadvice[] = { 168 { MADV_NORMAL, 3, 4 }, 169 { MADV_RANDOM, 0, 0 }, 170 { MADV_SEQUENTIAL, 8, 7}, 171 }; 172 173 #define UVM_MAXRANGE 16 /* must be max() of nback+nforw+1 */ 174 175 /* 176 * private prototypes 177 */ 178 179 static void uvmfault_amapcopy __P((struct uvm_faultinfo *)); 180 static __inline void uvmfault_anonflush __P((struct vm_anon **, int)); 181 182 /* 183 * inline functions 184 */ 185 186 /* 187 * uvmfault_anonflush: try and deactivate pages in specified anons 188 * 189 * => does not have to deactivate page if it is busy 190 */ 191 192 static __inline void 193 uvmfault_anonflush(anons, n) 194 struct vm_anon **anons; 195 int n; 196 { 197 int lcv; 198 struct vm_page *pg; 199 200 for (lcv = 0 ; lcv < n ; lcv++) { 201 if (anons[lcv] == NULL) 202 continue; 203 simple_lock(&anons[lcv]->an_lock); 204 pg = anons[lcv]->u.an_page; 205 if (pg && (pg->flags & PG_BUSY) == 0 && pg->loan_count == 0) { 206 uvm_lock_pageq(); 207 if (pg->wire_count == 0) { 208 pmap_clear_reference(pg); 209 uvm_pagedeactivate(pg); 210 } 211 uvm_unlock_pageq(); 212 } 213 simple_unlock(&anons[lcv]->an_lock); 214 } 215 } 216 217 /* 218 * normal functions 219 */ 220 221 /* 222 * uvmfault_amapcopy: clear "needs_copy" in a map. 223 * 224 * => called with VM data structures unlocked (usually, see below) 225 * => we get a write lock on the maps and clear needs_copy for a VA 226 * => if we are out of RAM we sleep (waiting for more) 227 */ 228 229 static void 230 uvmfault_amapcopy(ufi) 231 struct uvm_faultinfo *ufi; 232 { 233 234 /* 235 * while we haven't done the job 236 */ 237 238 while (1) { 239 240 /* 241 * no mapping? give up. 242 */ 243 244 if (uvmfault_lookup(ufi, TRUE) == FALSE) 245 return; 246 247 /* 248 * copy if needed. 249 */ 250 251 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) 252 amap_copy(ufi->map, ufi->entry, M_NOWAIT, TRUE, 253 ufi->orig_rvaddr, ufi->orig_rvaddr + 1); 254 255 /* 256 * didn't work? must be out of RAM. unlock and sleep. 257 */ 258 259 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 260 uvmfault_unlockmaps(ufi, TRUE); 261 uvm_wait("fltamapcopy"); 262 continue; 263 } 264 265 /* 266 * got it! unlock and return. 267 */ 268 269 uvmfault_unlockmaps(ufi, TRUE); 270 return; 271 } 272 /*NOTREACHED*/ 273 } 274 275 /* 276 * uvmfault_anonget: get data in an anon into a non-busy, non-released 277 * page in that anon. 278 * 279 * => maps, amap, and anon locked by caller. 280 * => if we fail (result != 0) we unlock everything. 281 * => if we are successful, we return with everything still locked. 282 * => we don't move the page on the queues [gets moved later] 283 * => if we allocate a new page [we_own], it gets put on the queues. 284 * either way, the result is that the page is on the queues at return time 285 * => for pages which are on loan from a uvm_object (and thus are not 286 * owned by the anon): if successful, we return with the owning object 287 * locked. the caller must unlock this object when it unlocks everything 288 * else. 289 */ 290 291 int 292 uvmfault_anonget(ufi, amap, anon) 293 struct uvm_faultinfo *ufi; 294 struct vm_amap *amap; 295 struct vm_anon *anon; 296 { 297 boolean_t we_own; /* we own anon's page? */ 298 boolean_t locked; /* did we relock? */ 299 struct vm_page *pg; 300 int error; 301 UVMHIST_FUNC("uvmfault_anonget"); UVMHIST_CALLED(maphist); 302 303 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 304 305 error = 0; 306 uvmexp.fltanget++; 307 /* bump rusage counters */ 308 if (anon->u.an_page) 309 curproc->p_addr->u_stats.p_ru.ru_minflt++; 310 else 311 curproc->p_addr->u_stats.p_ru.ru_majflt++; 312 313 /* 314 * loop until we get it, or fail. 315 */ 316 317 while (1) { 318 319 we_own = FALSE; /* TRUE if we set PG_BUSY on a page */ 320 pg = anon->u.an_page; 321 322 /* 323 * if there is a resident page and it is loaned, then anon 324 * may not own it. call out to uvm_anon_lockpage() to ensure 325 * the real owner of the page has been identified and locked. 326 */ 327 328 if (pg && pg->loan_count) 329 pg = uvm_anon_lockloanpg(anon); 330 331 /* 332 * page there? make sure it is not busy/released. 333 */ 334 335 if (pg) { 336 337 /* 338 * at this point, if the page has a uobject [meaning 339 * we have it on loan], then that uobject is locked 340 * by us! if the page is busy, we drop all the 341 * locks (including uobject) and try again. 342 */ 343 344 if ((pg->flags & (PG_BUSY|PG_RELEASED)) == 0) { 345 UVMHIST_LOG(maphist, "<- OK",0,0,0,0); 346 return (0); 347 } 348 pg->flags |= PG_WANTED; 349 uvmexp.fltpgwait++; 350 351 /* 352 * the last unlock must be an atomic unlock+wait on 353 * the owner of page 354 */ 355 if (pg->uobject) { /* owner is uobject ? */ 356 uvmfault_unlockall(ufi, amap, NULL, anon); 357 UVMHIST_LOG(maphist, " unlock+wait on uobj",0, 358 0,0,0); 359 UVM_UNLOCK_AND_WAIT(pg, 360 &pg->uobject->vmobjlock, 361 FALSE, "anonget1",0); 362 } else { 363 /* anon owns page */ 364 uvmfault_unlockall(ufi, amap, NULL, NULL); 365 UVMHIST_LOG(maphist, " unlock+wait on anon",0, 366 0,0,0); 367 UVM_UNLOCK_AND_WAIT(pg,&anon->an_lock,0, 368 "anonget2",0); 369 } 370 /* ready to relock and try again */ 371 372 } else { 373 374 /* 375 * no page, we must try and bring it in. 376 */ 377 pg = uvm_pagealloc(NULL, 0, anon, 0); 378 379 if (pg == NULL) { /* out of RAM. */ 380 381 uvmfault_unlockall(ufi, amap, NULL, anon); 382 uvmexp.fltnoram++; 383 UVMHIST_LOG(maphist, " noram -- UVM_WAIT",0, 384 0,0,0); 385 uvm_wait("flt_noram1"); 386 /* ready to relock and try again */ 387 388 } else { 389 390 /* we set the PG_BUSY bit */ 391 we_own = TRUE; 392 uvmfault_unlockall(ufi, amap, NULL, anon); 393 394 /* 395 * we are passing a PG_BUSY+PG_FAKE+PG_CLEAN 396 * page into the uvm_swap_get function with 397 * all data structures unlocked. note that 398 * it is ok to read an_swslot here because 399 * we hold PG_BUSY on the page. 400 */ 401 uvmexp.pageins++; 402 error = uvm_swap_get(pg, anon->an_swslot, 403 PGO_SYNCIO); 404 405 /* 406 * we clean up after the i/o below in the 407 * "we_own" case 408 */ 409 /* ready to relock and try again */ 410 } 411 } 412 413 /* 414 * now relock and try again 415 */ 416 417 locked = uvmfault_relock(ufi); 418 if (locked && amap != NULL) { 419 amap_lock(amap); 420 } 421 if (locked || we_own) 422 simple_lock(&anon->an_lock); 423 424 /* 425 * if we own the page (i.e. we set PG_BUSY), then we need 426 * to clean up after the I/O. there are three cases to 427 * consider: 428 * [1] page released during I/O: free anon and ReFault. 429 * [2] I/O not OK. free the page and cause the fault 430 * to fail. 431 * [3] I/O OK! activate the page and sync with the 432 * non-we_own case (i.e. drop anon lock if not locked). 433 */ 434 435 if (we_own) { 436 437 if (pg->flags & PG_WANTED) { 438 /* still holding object lock */ 439 wakeup(pg); 440 } 441 /* un-busy! */ 442 pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE); 443 UVM_PAGE_OWN(pg, NULL); 444 445 /* 446 * if we were RELEASED during I/O, then our anon is 447 * no longer part of an amap. we need to free the 448 * anon and try again. 449 */ 450 if (pg->flags & PG_RELEASED) { 451 pmap_page_protect(pg, VM_PROT_NONE); 452 simple_unlock(&anon->an_lock); 453 uvm_anfree(anon); /* frees page for us */ 454 if (locked) 455 uvmfault_unlockall(ufi, amap, NULL, 456 NULL); 457 uvmexp.fltpgrele++; 458 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 459 return (ERESTART); /* refault! */ 460 } 461 462 if (error) { 463 /* remove page from anon */ 464 anon->u.an_page = NULL; 465 466 /* 467 * remove the swap slot from the anon 468 * and mark the anon as having no real slot. 469 * don't free the swap slot, thus preventing 470 * it from being used again. 471 */ 472 uvm_swap_markbad(anon->an_swslot, 1); 473 anon->an_swslot = SWSLOT_BAD; 474 475 /* 476 * note: page was never !PG_BUSY, so it 477 * can't be mapped and thus no need to 478 * pmap_page_protect it... 479 */ 480 uvm_lock_pageq(); 481 uvm_pagefree(pg); 482 uvm_unlock_pageq(); 483 484 if (locked) 485 uvmfault_unlockall(ufi, amap, NULL, 486 anon); 487 else 488 simple_unlock(&anon->an_lock); 489 UVMHIST_LOG(maphist, "<- ERROR", 0,0,0,0); 490 return error; 491 } 492 493 /* 494 * must be OK, clear modify (already PG_CLEAN) 495 * and activate 496 */ 497 pmap_clear_modify(pg); 498 uvm_lock_pageq(); 499 uvm_pageactivate(pg); 500 uvm_unlock_pageq(); 501 if (!locked) 502 simple_unlock(&anon->an_lock); 503 } 504 505 /* 506 * we were not able to relock. restart fault. 507 */ 508 509 if (!locked) { 510 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 511 return (ERESTART); 512 } 513 514 /* 515 * verify no one has touched the amap and moved the anon on us. 516 */ 517 518 if (ufi != NULL && 519 amap_lookup(&ufi->entry->aref, 520 ufi->orig_rvaddr - ufi->entry->start) != anon) { 521 522 uvmfault_unlockall(ufi, amap, NULL, anon); 523 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 524 return (ERESTART); 525 } 526 527 /* 528 * try it again! 529 */ 530 531 uvmexp.fltanretry++; 532 continue; 533 534 } /* while (1) */ 535 536 /*NOTREACHED*/ 537 } 538 539 /* 540 * F A U L T - m a i n e n t r y p o i n t 541 */ 542 543 /* 544 * uvm_fault: page fault handler 545 * 546 * => called from MD code to resolve a page fault 547 * => VM data structures usually should be unlocked. however, it is 548 * possible to call here with the main map locked if the caller 549 * gets a write lock, sets it recusive, and then calls us (c.f. 550 * uvm_map_pageable). this should be avoided because it keeps 551 * the map locked off during I/O. 552 * => MUST NEVER BE CALLED IN INTERRUPT CONTEXT 553 */ 554 555 #define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \ 556 ~VM_PROT_WRITE : VM_PROT_ALL) 557 558 int 559 uvm_fault(orig_map, vaddr, fault_type, access_type) 560 struct vm_map *orig_map; 561 vaddr_t vaddr; 562 vm_fault_t fault_type; 563 vm_prot_t access_type; 564 { 565 struct uvm_faultinfo ufi; 566 vm_prot_t enter_prot; 567 boolean_t wired, narrow, promote, locked, shadowed; 568 int npages, nback, nforw, centeridx, error, lcv, gotpages; 569 vaddr_t startva, objaddr, currva, offset, uoff; 570 paddr_t pa; 571 struct vm_amap *amap; 572 struct uvm_object *uobj; 573 struct vm_anon *anons_store[UVM_MAXRANGE], **anons, *anon, *oanon; 574 struct vm_page *pages[UVM_MAXRANGE], *pg, *uobjpage; 575 UVMHIST_FUNC("uvm_fault"); UVMHIST_CALLED(maphist); 576 577 UVMHIST_LOG(maphist, "(map=0x%x, vaddr=0x%x, ft=%d, at=%d)", 578 orig_map, vaddr, fault_type, access_type); 579 580 anon = NULL; 581 pg = NULL; 582 583 uvmexp.faults++; /* XXX: locking? */ 584 585 /* 586 * init the IN parameters in the ufi 587 */ 588 589 ufi.orig_map = orig_map; 590 ufi.orig_rvaddr = trunc_page(vaddr); 591 ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */ 592 if (fault_type == VM_FAULT_WIRE) 593 narrow = TRUE; /* don't look for neighborhood 594 * pages on wire */ 595 else 596 narrow = FALSE; /* normal fault */ 597 598 /* 599 * "goto ReFault" means restart the page fault from ground zero. 600 */ 601 ReFault: 602 603 /* 604 * lookup and lock the maps 605 */ 606 607 if (uvmfault_lookup(&ufi, FALSE) == FALSE) { 608 UVMHIST_LOG(maphist, "<- no mapping @ 0x%x", vaddr, 0,0,0); 609 return (EFAULT); 610 } 611 /* locked: maps(read) */ 612 613 #ifdef DIAGNOSTIC 614 if ((ufi.map->flags & VM_MAP_PAGEABLE) == 0) { 615 printf("Page fault on non-pageable map:\n"); 616 printf("ufi.map = %p\n", ufi.map); 617 printf("ufi.orig_map = %p\n", ufi.orig_map); 618 printf("ufi.orig_rvaddr = 0x%lx\n", (u_long) ufi.orig_rvaddr); 619 panic("uvm_fault: (ufi.map->flags & VM_MAP_PAGEABLE) == 0"); 620 } 621 #endif 622 623 /* 624 * check protection 625 */ 626 627 if ((ufi.entry->protection & access_type) != access_type) { 628 UVMHIST_LOG(maphist, 629 "<- protection failure (prot=0x%x, access=0x%x)", 630 ufi.entry->protection, access_type, 0, 0); 631 uvmfault_unlockmaps(&ufi, FALSE); 632 return EACCES; 633 } 634 635 /* 636 * "enter_prot" is the protection we want to enter the page in at. 637 * for certain pages (e.g. copy-on-write pages) this protection can 638 * be more strict than ufi.entry->protection. "wired" means either 639 * the entry is wired or we are fault-wiring the pg. 640 */ 641 642 enter_prot = ufi.entry->protection; 643 wired = VM_MAPENT_ISWIRED(ufi.entry) || (fault_type == VM_FAULT_WIRE); 644 if (wired) 645 access_type = enter_prot; /* full access for wired */ 646 647 /* 648 * handle "needs_copy" case. if we need to copy the amap we will 649 * have to drop our readlock and relock it with a write lock. (we 650 * need a write lock to change anything in a map entry [e.g. 651 * needs_copy]). 652 */ 653 654 if (UVM_ET_ISNEEDSCOPY(ufi.entry)) { 655 if ((access_type & VM_PROT_WRITE) || 656 (ufi.entry->object.uvm_obj == NULL)) { 657 /* need to clear */ 658 UVMHIST_LOG(maphist, 659 " need to clear needs_copy and refault",0,0,0,0); 660 uvmfault_unlockmaps(&ufi, FALSE); 661 uvmfault_amapcopy(&ufi); 662 uvmexp.fltamcopy++; 663 goto ReFault; 664 665 } else { 666 667 /* 668 * ensure that we pmap_enter page R/O since 669 * needs_copy is still true 670 */ 671 enter_prot &= ~VM_PROT_WRITE; 672 673 } 674 } 675 676 /* 677 * identify the players 678 */ 679 680 amap = ufi.entry->aref.ar_amap; /* top layer */ 681 uobj = ufi.entry->object.uvm_obj; /* bottom layer */ 682 683 /* 684 * check for a case 0 fault. if nothing backing the entry then 685 * error now. 686 */ 687 688 if (amap == NULL && uobj == NULL) { 689 uvmfault_unlockmaps(&ufi, FALSE); 690 UVMHIST_LOG(maphist,"<- no backing store, no overlay",0,0,0,0); 691 return (EFAULT); 692 } 693 694 /* 695 * establish range of interest based on advice from mapper 696 * and then clip to fit map entry. note that we only want 697 * to do this the first time through the fault. if we 698 * ReFault we will disable this by setting "narrow" to true. 699 */ 700 701 if (narrow == FALSE) { 702 703 /* wide fault (!narrow) */ 704 KASSERT(uvmadvice[ufi.entry->advice].advice == 705 ufi.entry->advice); 706 nback = min(uvmadvice[ufi.entry->advice].nback, 707 (ufi.orig_rvaddr - ufi.entry->start) >> PAGE_SHIFT); 708 startva = ufi.orig_rvaddr - (nback << PAGE_SHIFT); 709 nforw = min(uvmadvice[ufi.entry->advice].nforw, 710 ((ufi.entry->end - ufi.orig_rvaddr) >> 711 PAGE_SHIFT) - 1); 712 /* 713 * note: "-1" because we don't want to count the 714 * faulting page as forw 715 */ 716 npages = nback + nforw + 1; 717 centeridx = nback; 718 719 narrow = TRUE; /* ensure only once per-fault */ 720 721 } else { 722 723 /* narrow fault! */ 724 nback = nforw = 0; 725 startva = ufi.orig_rvaddr; 726 npages = 1; 727 centeridx = 0; 728 729 } 730 731 /* locked: maps(read) */ 732 UVMHIST_LOG(maphist, " narrow=%d, back=%d, forw=%d, startva=0x%x", 733 narrow, nback, nforw, startva); 734 UVMHIST_LOG(maphist, " entry=0x%x, amap=0x%x, obj=0x%x", ufi.entry, 735 amap, uobj, 0); 736 737 /* 738 * if we've got an amap, lock it and extract current anons. 739 */ 740 741 if (amap) { 742 amap_lock(amap); 743 anons = anons_store; 744 amap_lookups(&ufi.entry->aref, startva - ufi.entry->start, 745 anons, npages); 746 } else { 747 anons = NULL; /* to be safe */ 748 } 749 750 /* locked: maps(read), amap(if there) */ 751 752 /* 753 * for MADV_SEQUENTIAL mappings we want to deactivate the back pages 754 * now and then forget about them (for the rest of the fault). 755 */ 756 757 if (ufi.entry->advice == MADV_SEQUENTIAL) { 758 759 UVMHIST_LOG(maphist, " MADV_SEQUENTIAL: flushing backpages", 760 0,0,0,0); 761 /* flush back-page anons? */ 762 if (amap) 763 uvmfault_anonflush(anons, nback); 764 765 /* flush object? */ 766 if (uobj) { 767 objaddr = 768 (startva - ufi.entry->start) + ufi.entry->offset; 769 simple_lock(&uobj->vmobjlock); 770 (void) uobj->pgops->pgo_flush(uobj, objaddr, objaddr + 771 (nback << PAGE_SHIFT), PGO_DEACTIVATE); 772 simple_unlock(&uobj->vmobjlock); 773 } 774 775 /* now forget about the backpages */ 776 if (amap) 777 anons += nback; 778 startva += (nback << PAGE_SHIFT); 779 npages -= nback; 780 nback = centeridx = 0; 781 } 782 783 /* locked: maps(read), amap(if there) */ 784 785 /* 786 * map in the backpages and frontpages we found in the amap in hopes 787 * of preventing future faults. we also init the pages[] array as 788 * we go. 789 */ 790 791 currva = startva; 792 shadowed = FALSE; 793 for (lcv = 0 ; lcv < npages ; lcv++, currva += PAGE_SIZE) { 794 795 /* 796 * dont play with VAs that are already mapped 797 * except for center) 798 */ 799 if (lcv != centeridx && 800 pmap_extract(ufi.orig_map->pmap, currva, &pa)) { 801 pages[lcv] = PGO_DONTCARE; 802 continue; 803 } 804 805 /* 806 * unmapped or center page. check if any anon at this level. 807 */ 808 if (amap == NULL || anons[lcv] == NULL) { 809 pages[lcv] = NULL; 810 continue; 811 } 812 813 /* 814 * check for present page and map if possible. re-activate it. 815 */ 816 817 pages[lcv] = PGO_DONTCARE; 818 if (lcv == centeridx) { /* save center for later! */ 819 shadowed = TRUE; 820 continue; 821 } 822 anon = anons[lcv]; 823 simple_lock(&anon->an_lock); 824 /* ignore loaned pages */ 825 if (anon->u.an_page && anon->u.an_page->loan_count == 0 && 826 (anon->u.an_page->flags & (PG_RELEASED|PG_BUSY)) == 0) { 827 uvm_lock_pageq(); 828 uvm_pageactivate(anon->u.an_page); /* reactivate */ 829 uvm_unlock_pageq(); 830 UVMHIST_LOG(maphist, 831 " MAPPING: n anon: pm=0x%x, va=0x%x, pg=0x%x", 832 ufi.orig_map->pmap, currva, anon->u.an_page, 0); 833 uvmexp.fltnamap++; 834 835 /* 836 * Since this isn't the page that's actually faulting, 837 * ignore pmap_enter() failures; it's not critical 838 * that we enter these right now. 839 */ 840 841 (void) pmap_enter(ufi.orig_map->pmap, currva, 842 VM_PAGE_TO_PHYS(anon->u.an_page), 843 (anon->an_ref > 1) ? (enter_prot & ~VM_PROT_WRITE) : 844 enter_prot, 845 PMAP_CANFAIL | 846 (VM_MAPENT_ISWIRED(ufi.entry) ? PMAP_WIRED : 0)); 847 } 848 simple_unlock(&anon->an_lock); 849 pmap_update(); 850 } 851 852 /* locked: maps(read), amap(if there) */ 853 /* (shadowed == TRUE) if there is an anon at the faulting address */ 854 UVMHIST_LOG(maphist, " shadowed=%d, will_get=%d", shadowed, 855 (uobj && shadowed == FALSE),0,0); 856 857 /* 858 * note that if we are really short of RAM we could sleep in the above 859 * call to pmap_enter with everything locked. bad? 860 * 861 * XXX Actually, that is bad; pmap_enter() should just fail in that 862 * XXX case. --thorpej 863 */ 864 865 /* 866 * if the desired page is not shadowed by the amap and we have a 867 * backing object, then we check to see if the backing object would 868 * prefer to handle the fault itself (rather than letting us do it 869 * with the usual pgo_get hook). the backing object signals this by 870 * providing a pgo_fault routine. 871 */ 872 873 if (uobj && shadowed == FALSE && uobj->pgops->pgo_fault != NULL) { 874 simple_lock(&uobj->vmobjlock); 875 876 /* locked: maps(read), amap (if there), uobj */ 877 error = uobj->pgops->pgo_fault(&ufi, startva, pages, npages, 878 centeridx, fault_type, access_type, PGO_LOCKED|PGO_SYNCIO); 879 880 /* locked: nothing, pgo_fault has unlocked everything */ 881 882 if (error == ERESTART) 883 goto ReFault; /* try again! */ 884 /* 885 * object fault routine responsible for pmap_update(). 886 */ 887 return error; 888 } 889 890 /* 891 * now, if the desired page is not shadowed by the amap and we have 892 * a backing object that does not have a special fault routine, then 893 * we ask (with pgo_get) the object for resident pages that we care 894 * about and attempt to map them in. we do not let pgo_get block 895 * (PGO_LOCKED). 896 * 897 * ("get" has the option of doing a pmap_enter for us) 898 */ 899 900 if (uobj && shadowed == FALSE) { 901 simple_lock(&uobj->vmobjlock); 902 903 /* locked (!shadowed): maps(read), amap (if there), uobj */ 904 /* 905 * the following call to pgo_get does _not_ change locking state 906 */ 907 908 uvmexp.fltlget++; 909 gotpages = npages; 910 (void) uobj->pgops->pgo_get(uobj, ufi.entry->offset + 911 (startva - ufi.entry->start), 912 pages, &gotpages, centeridx, 913 access_type & MASK(ufi.entry), 914 ufi.entry->advice, PGO_LOCKED); 915 916 /* 917 * check for pages to map, if we got any 918 */ 919 920 uobjpage = NULL; 921 922 if (gotpages) { 923 currva = startva; 924 for (lcv = 0 ; lcv < npages ; 925 lcv++, currva += PAGE_SIZE) { 926 927 if (pages[lcv] == NULL || 928 pages[lcv] == PGO_DONTCARE) 929 continue; 930 931 KASSERT((pages[lcv]->flags & PG_RELEASED) == 0); 932 933 /* 934 * if center page is resident and not 935 * PG_BUSY|PG_RELEASED then pgo_get 936 * made it PG_BUSY for us and gave 937 * us a handle to it. remember this 938 * page as "uobjpage." (for later use). 939 */ 940 941 if (lcv == centeridx) { 942 uobjpage = pages[lcv]; 943 UVMHIST_LOG(maphist, " got uobjpage " 944 "(0x%x) with locked get", 945 uobjpage, 0,0,0); 946 continue; 947 } 948 949 /* 950 * note: calling pgo_get with locked data 951 * structures returns us pages which are 952 * neither busy nor released, so we don't 953 * need to check for this. we can just 954 * directly enter the page (after moving it 955 * to the head of the active queue [useful?]). 956 */ 957 958 uvm_lock_pageq(); 959 uvm_pageactivate(pages[lcv]); /* reactivate */ 960 uvm_unlock_pageq(); 961 UVMHIST_LOG(maphist, 962 " MAPPING: n obj: pm=0x%x, va=0x%x, pg=0x%x", 963 ufi.orig_map->pmap, currva, pages[lcv], 0); 964 uvmexp.fltnomap++; 965 966 /* 967 * Since this page isn't the page that's 968 * actually fauling, ignore pmap_enter() 969 * failures; it's not critical that we 970 * enter these right now. 971 */ 972 973 (void) pmap_enter(ufi.orig_map->pmap, currva, 974 VM_PAGE_TO_PHYS(pages[lcv]), 975 pages[lcv]->flags & PG_RDONLY ? 976 VM_PROT_READ : enter_prot & MASK(ufi.entry), 977 PMAP_CANFAIL | 978 (wired ? PMAP_WIRED : 0)); 979 980 /* 981 * NOTE: page can't be PG_WANTED or PG_RELEASED 982 * because we've held the lock the whole time 983 * we've had the handle. 984 */ 985 986 pages[lcv]->flags &= ~(PG_BUSY); /* un-busy! */ 987 UVM_PAGE_OWN(pages[lcv], NULL); 988 } /* for "lcv" loop */ 989 pmap_update(); 990 } /* "gotpages" != 0 */ 991 /* note: object still _locked_ */ 992 } else { 993 uobjpage = NULL; 994 } 995 996 /* locked (shadowed): maps(read), amap */ 997 /* locked (!shadowed): maps(read), amap(if there), 998 uobj(if !null), uobjpage(if !null) */ 999 1000 /* 1001 * note that at this point we are done with any front or back pages. 1002 * we are now going to focus on the center page (i.e. the one we've 1003 * faulted on). if we have faulted on the top (anon) layer 1004 * [i.e. case 1], then the anon we want is anons[centeridx] (we have 1005 * not touched it yet). if we have faulted on the bottom (uobj) 1006 * layer [i.e. case 2] and the page was both present and available, 1007 * then we've got a pointer to it as "uobjpage" and we've already 1008 * made it BUSY. 1009 */ 1010 1011 /* 1012 * there are four possible cases we must address: 1A, 1B, 2A, and 2B 1013 */ 1014 1015 /* 1016 * redirect case 2: if we are not shadowed, go to case 2. 1017 */ 1018 1019 if (shadowed == FALSE) 1020 goto Case2; 1021 1022 /* locked: maps(read), amap */ 1023 1024 /* 1025 * handle case 1: fault on an anon in our amap 1026 */ 1027 1028 anon = anons[centeridx]; 1029 UVMHIST_LOG(maphist, " case 1 fault: anon=0x%x", anon, 0,0,0); 1030 simple_lock(&anon->an_lock); 1031 1032 /* locked: maps(read), amap, anon */ 1033 1034 /* 1035 * no matter if we have case 1A or case 1B we are going to need to 1036 * have the anon's memory resident. ensure that now. 1037 */ 1038 1039 /* 1040 * let uvmfault_anonget do the dirty work. 1041 * if it fails (!OK) it will unlock everything for us. 1042 * if it succeeds, locks are still valid and locked. 1043 * also, if it is OK, then the anon's page is on the queues. 1044 * if the page is on loan from a uvm_object, then anonget will 1045 * lock that object for us if it does not fail. 1046 */ 1047 1048 error = uvmfault_anonget(&ufi, amap, anon); 1049 switch (error) { 1050 case 0: 1051 break; 1052 1053 case ERESTART: 1054 goto ReFault; 1055 1056 case EAGAIN: 1057 tsleep(&lbolt, PVM, "fltagain1", 0); 1058 goto ReFault; 1059 1060 default: 1061 return error; 1062 } 1063 1064 /* 1065 * uobj is non null if the page is on loan from an object (i.e. uobj) 1066 */ 1067 1068 uobj = anon->u.an_page->uobject; /* locked by anonget if !NULL */ 1069 1070 /* locked: maps(read), amap, anon, uobj(if one) */ 1071 1072 /* 1073 * special handling for loaned pages 1074 */ 1075 1076 if (anon->u.an_page->loan_count) { 1077 1078 if ((access_type & VM_PROT_WRITE) == 0) { 1079 1080 /* 1081 * for read faults on loaned pages we just cap the 1082 * protection at read-only. 1083 */ 1084 1085 enter_prot = enter_prot & ~VM_PROT_WRITE; 1086 1087 } else { 1088 /* 1089 * note that we can't allow writes into a loaned page! 1090 * 1091 * if we have a write fault on a loaned page in an 1092 * anon then we need to look at the anon's ref count. 1093 * if it is greater than one then we are going to do 1094 * a normal copy-on-write fault into a new anon (this 1095 * is not a problem). however, if the reference count 1096 * is one (a case where we would normally allow a 1097 * write directly to the page) then we need to kill 1098 * the loan before we continue. 1099 */ 1100 1101 /* >1 case is already ok */ 1102 if (anon->an_ref == 1) { 1103 1104 /* get new un-owned replacement page */ 1105 pg = uvm_pagealloc(NULL, 0, NULL, 0); 1106 if (pg == NULL) { 1107 uvmfault_unlockall(&ufi, amap, uobj, 1108 anon); 1109 uvm_wait("flt_noram2"); 1110 goto ReFault; 1111 } 1112 1113 /* 1114 * copy data, kill loan, and drop uobj lock 1115 * (if any) 1116 */ 1117 /* copy old -> new */ 1118 uvm_pagecopy(anon->u.an_page, pg); 1119 1120 /* force reload */ 1121 pmap_page_protect(anon->u.an_page, 1122 VM_PROT_NONE); 1123 uvm_lock_pageq(); /* KILL loan */ 1124 if (uobj) 1125 /* if we were loaning */ 1126 anon->u.an_page->loan_count--; 1127 anon->u.an_page->uanon = NULL; 1128 /* in case we owned */ 1129 anon->u.an_page->pqflags &= ~PQ_ANON; 1130 uvm_unlock_pageq(); 1131 if (uobj) { 1132 simple_unlock(&uobj->vmobjlock); 1133 uobj = NULL; 1134 } 1135 1136 /* install new page in anon */ 1137 anon->u.an_page = pg; 1138 pg->uanon = anon; 1139 pg->pqflags |= PQ_ANON; 1140 pg->flags &= ~(PG_BUSY|PG_FAKE); 1141 UVM_PAGE_OWN(pg, NULL); 1142 1143 /* done! */ 1144 } /* ref == 1 */ 1145 } /* write fault */ 1146 } /* loan count */ 1147 1148 /* 1149 * if we are case 1B then we will need to allocate a new blank 1150 * anon to transfer the data into. note that we have a lock 1151 * on anon, so no one can busy or release the page until we are done. 1152 * also note that the ref count can't drop to zero here because 1153 * it is > 1 and we are only dropping one ref. 1154 * 1155 * in the (hopefully very rare) case that we are out of RAM we 1156 * will unlock, wait for more RAM, and refault. 1157 * 1158 * if we are out of anon VM we kill the process (XXX: could wait?). 1159 */ 1160 1161 if ((access_type & VM_PROT_WRITE) != 0 && anon->an_ref > 1) { 1162 1163 UVMHIST_LOG(maphist, " case 1B: COW fault",0,0,0,0); 1164 uvmexp.flt_acow++; 1165 oanon = anon; /* oanon = old, locked anon */ 1166 anon = uvm_analloc(); 1167 if (anon) { 1168 /* new anon is locked! */ 1169 pg = uvm_pagealloc(NULL, 0, anon, 0); 1170 } 1171 1172 /* check for out of RAM */ 1173 if (anon == NULL || pg == NULL) { 1174 if (anon) { 1175 anon->an_ref--; 1176 simple_unlock(&anon->an_lock); 1177 uvm_anfree(anon); 1178 } 1179 uvmfault_unlockall(&ufi, amap, uobj, oanon); 1180 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 1181 if (anon == NULL || uvmexp.swpgonly == uvmexp.swpages) { 1182 UVMHIST_LOG(maphist, 1183 "<- failed. out of VM",0,0,0,0); 1184 uvmexp.fltnoanon++; 1185 return ENOMEM; 1186 } 1187 1188 uvmexp.fltnoram++; 1189 uvm_wait("flt_noram3"); /* out of RAM, wait for more */ 1190 goto ReFault; 1191 } 1192 1193 /* got all resources, replace anon with nanon */ 1194 1195 uvm_pagecopy(oanon->u.an_page, pg); /* pg now !PG_CLEAN */ 1196 pg->flags &= ~(PG_BUSY|PG_FAKE); /* un-busy! new page */ 1197 UVM_PAGE_OWN(pg, NULL); 1198 amap_add(&ufi.entry->aref, ufi.orig_rvaddr - ufi.entry->start, 1199 anon, 1); 1200 1201 /* deref: can not drop to zero here by defn! */ 1202 oanon->an_ref--; 1203 1204 /* 1205 * note: oanon is still locked, as is the new anon. we 1206 * need to check for this later when we unlock oanon; if 1207 * oanon != anon, we'll have to unlock anon, too. 1208 */ 1209 1210 } else { 1211 1212 uvmexp.flt_anon++; 1213 oanon = anon; /* old, locked anon is same as anon */ 1214 pg = anon->u.an_page; 1215 if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */ 1216 enter_prot = enter_prot & ~VM_PROT_WRITE; 1217 1218 } 1219 1220 /* locked: maps(read), amap, oanon, anon (if different from oanon) */ 1221 1222 /* 1223 * now map the page in ... 1224 * XXX: old fault unlocks object before pmap_enter. this seems 1225 * suspect since some other thread could blast the page out from 1226 * under us between the unlock and the pmap_enter. 1227 */ 1228 1229 UVMHIST_LOG(maphist, " MAPPING: anon: pm=0x%x, va=0x%x, pg=0x%x", 1230 ufi.orig_map->pmap, ufi.orig_rvaddr, pg, 0); 1231 if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg), 1232 enter_prot, access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0)) 1233 != 0) { 1234 /* 1235 * No need to undo what we did; we can simply think of 1236 * this as the pmap throwing away the mapping information. 1237 * 1238 * We do, however, have to go through the ReFault path, 1239 * as the map may change while we're asleep. 1240 */ 1241 if (anon != oanon) 1242 simple_unlock(&anon->an_lock); 1243 uvmfault_unlockall(&ufi, amap, uobj, oanon); 1244 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 1245 if (uvmexp.swpgonly == uvmexp.swpages) { 1246 UVMHIST_LOG(maphist, 1247 "<- failed. out of VM",0,0,0,0); 1248 /* XXX instrumentation */ 1249 return ENOMEM; 1250 } 1251 /* XXX instrumentation */ 1252 uvm_wait("flt_pmfail1"); 1253 goto ReFault; 1254 } 1255 1256 /* 1257 * ... update the page queues. 1258 */ 1259 1260 uvm_lock_pageq(); 1261 1262 if (fault_type == VM_FAULT_WIRE) { 1263 uvm_pagewire(pg); 1264 1265 /* 1266 * since the now-wired page cannot be paged out, 1267 * release its swap resources for others to use. 1268 * since an anon with no swap cannot be PG_CLEAN, 1269 * clear its clean flag now. 1270 */ 1271 1272 pg->flags &= ~(PG_CLEAN); 1273 uvm_anon_dropswap(anon); 1274 } else { 1275 /* activate it */ 1276 uvm_pageactivate(pg); 1277 } 1278 1279 uvm_unlock_pageq(); 1280 1281 /* 1282 * done case 1! finish up by unlocking everything and returning success 1283 */ 1284 1285 if (anon != oanon) 1286 simple_unlock(&anon->an_lock); 1287 uvmfault_unlockall(&ufi, amap, uobj, oanon); 1288 pmap_update(); 1289 return 0; 1290 1291 1292 Case2: 1293 /* 1294 * handle case 2: faulting on backing object or zero fill 1295 */ 1296 1297 /* 1298 * locked: 1299 * maps(read), amap(if there), uobj(if !null), uobjpage(if !null) 1300 */ 1301 1302 /* 1303 * note that uobjpage can not be PGO_DONTCARE at this point. we now 1304 * set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we 1305 * have a backing object, check and see if we are going to promote 1306 * the data up to an anon during the fault. 1307 */ 1308 1309 if (uobj == NULL) { 1310 uobjpage = PGO_DONTCARE; 1311 promote = TRUE; /* always need anon here */ 1312 } else { 1313 KASSERT(uobjpage != PGO_DONTCARE); 1314 promote = (access_type & VM_PROT_WRITE) && 1315 UVM_ET_ISCOPYONWRITE(ufi.entry); 1316 } 1317 UVMHIST_LOG(maphist, " case 2 fault: promote=%d, zfill=%d", 1318 promote, (uobj == NULL), 0,0); 1319 1320 /* 1321 * if uobjpage is not null then we do not need to do I/O to get the 1322 * uobjpage. 1323 * 1324 * if uobjpage is null, then we need to unlock and ask the pager to 1325 * get the data for us. once we have the data, we need to reverify 1326 * the state the world. we are currently not holding any resources. 1327 */ 1328 1329 if (uobjpage) { 1330 /* update rusage counters */ 1331 curproc->p_addr->u_stats.p_ru.ru_minflt++; 1332 } else { 1333 /* update rusage counters */ 1334 curproc->p_addr->u_stats.p_ru.ru_majflt++; 1335 1336 /* locked: maps(read), amap(if there), uobj */ 1337 uvmfault_unlockall(&ufi, amap, NULL, NULL); 1338 /* locked: uobj */ 1339 1340 uvmexp.fltget++; 1341 gotpages = 1; 1342 uoff = (ufi.orig_rvaddr - ufi.entry->start) + ufi.entry->offset; 1343 error = uobj->pgops->pgo_get(uobj, uoff, &uobjpage, &gotpages, 1344 0, access_type & MASK(ufi.entry), ufi.entry->advice, 1345 PGO_SYNCIO); 1346 1347 /* locked: uobjpage(if no error) */ 1348 1349 /* 1350 * recover from I/O 1351 */ 1352 1353 if (error) { 1354 if (error == EAGAIN) { 1355 UVMHIST_LOG(maphist, 1356 " pgo_get says TRY AGAIN!",0,0,0,0); 1357 tsleep(&lbolt, PVM, "fltagain2", 0); 1358 goto ReFault; 1359 } 1360 1361 UVMHIST_LOG(maphist, "<- pgo_get failed (code %d)", 1362 error, 0,0,0); 1363 return error; 1364 } 1365 1366 /* locked: uobjpage */ 1367 1368 /* 1369 * re-verify the state of the world by first trying to relock 1370 * the maps. always relock the object. 1371 */ 1372 1373 locked = uvmfault_relock(&ufi); 1374 if (locked && amap) 1375 amap_lock(amap); 1376 simple_lock(&uobj->vmobjlock); 1377 1378 /* locked(locked): maps(read), amap(if !null), uobj, uobjpage */ 1379 /* locked(!locked): uobj, uobjpage */ 1380 1381 /* 1382 * verify that the page has not be released and re-verify 1383 * that amap slot is still free. if there is a problem, 1384 * we unlock and clean up. 1385 */ 1386 1387 if ((uobjpage->flags & PG_RELEASED) != 0 || 1388 (locked && amap && 1389 amap_lookup(&ufi.entry->aref, 1390 ufi.orig_rvaddr - ufi.entry->start))) { 1391 if (locked) 1392 uvmfault_unlockall(&ufi, amap, NULL, NULL); 1393 locked = FALSE; 1394 } 1395 1396 /* 1397 * didn't get the lock? release the page and retry. 1398 */ 1399 1400 if (locked == FALSE) { 1401 1402 UVMHIST_LOG(maphist, 1403 " wasn't able to relock after fault: retry", 1404 0,0,0,0); 1405 if (uobjpage->flags & PG_WANTED) 1406 /* still holding object lock */ 1407 wakeup(uobjpage); 1408 1409 if (uobjpage->flags & PG_RELEASED) { 1410 uvmexp.fltpgrele++; 1411 KASSERT(uobj->pgops->pgo_releasepg != NULL); 1412 1413 /* frees page */ 1414 if (uobj->pgops->pgo_releasepg(uobjpage,NULL)) 1415 /* unlock if still alive */ 1416 simple_unlock(&uobj->vmobjlock); 1417 goto ReFault; 1418 } 1419 1420 uvm_lock_pageq(); 1421 /* make sure it is in queues */ 1422 uvm_pageactivate(uobjpage); 1423 1424 uvm_unlock_pageq(); 1425 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1426 UVM_PAGE_OWN(uobjpage, NULL); 1427 simple_unlock(&uobj->vmobjlock); 1428 goto ReFault; 1429 1430 } 1431 1432 /* 1433 * we have the data in uobjpage which is PG_BUSY and 1434 * !PG_RELEASED. we are holding object lock (so the page 1435 * can't be released on us). 1436 */ 1437 1438 /* locked: maps(read), amap(if !null), uobj, uobjpage */ 1439 } 1440 1441 /* 1442 * locked: 1443 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj) 1444 */ 1445 1446 /* 1447 * notes: 1448 * - at this point uobjpage can not be NULL 1449 * - at this point uobjpage can not be PG_RELEASED (since we checked 1450 * for it above) 1451 * - at this point uobjpage could be PG_WANTED (handle later) 1452 */ 1453 1454 if (promote == FALSE) { 1455 1456 /* 1457 * we are not promoting. if the mapping is COW ensure that we 1458 * don't give more access than we should (e.g. when doing a read 1459 * fault on a COPYONWRITE mapping we want to map the COW page in 1460 * R/O even though the entry protection could be R/W). 1461 * 1462 * set "pg" to the page we want to map in (uobjpage, usually) 1463 */ 1464 1465 /* no anon in this case. */ 1466 anon = NULL; 1467 1468 uvmexp.flt_obj++; 1469 if (UVM_ET_ISCOPYONWRITE(ufi.entry)) 1470 enter_prot &= ~VM_PROT_WRITE; 1471 pg = uobjpage; /* map in the actual object */ 1472 1473 /* assert(uobjpage != PGO_DONTCARE) */ 1474 1475 /* 1476 * we are faulting directly on the page. be careful 1477 * about writing to loaned pages... 1478 */ 1479 if (uobjpage->loan_count) { 1480 1481 if ((access_type & VM_PROT_WRITE) == 0) { 1482 /* read fault: cap the protection at readonly */ 1483 /* cap! */ 1484 enter_prot = enter_prot & ~VM_PROT_WRITE; 1485 } else { 1486 /* write fault: must break the loan here */ 1487 1488 /* alloc new un-owned page */ 1489 pg = uvm_pagealloc(NULL, 0, NULL, 0); 1490 1491 if (pg == NULL) { 1492 /* 1493 * drop ownership of page, it can't 1494 * be released 1495 */ 1496 if (uobjpage->flags & PG_WANTED) 1497 wakeup(uobjpage); 1498 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1499 UVM_PAGE_OWN(uobjpage, NULL); 1500 1501 uvm_lock_pageq(); 1502 /* activate: we will need it later */ 1503 uvm_pageactivate(uobjpage); 1504 1505 uvm_unlock_pageq(); 1506 uvmfault_unlockall(&ufi, amap, uobj, 1507 NULL); 1508 UVMHIST_LOG(maphist, 1509 " out of RAM breaking loan, waiting", 1510 0,0,0,0); 1511 uvmexp.fltnoram++; 1512 uvm_wait("flt_noram4"); 1513 goto ReFault; 1514 } 1515 1516 /* 1517 * copy the data from the old page to the new 1518 * one and clear the fake/clean flags on the 1519 * new page (keep it busy). force a reload 1520 * of the old page by clearing it from all 1521 * pmaps. then lock the page queues to 1522 * rename the pages. 1523 */ 1524 uvm_pagecopy(uobjpage, pg); /* old -> new */ 1525 pg->flags &= ~(PG_FAKE|PG_CLEAN); 1526 pmap_page_protect(uobjpage, VM_PROT_NONE); 1527 if (uobjpage->flags & PG_WANTED) 1528 wakeup(uobjpage); 1529 /* uobj still locked */ 1530 uobjpage->flags &= ~(PG_WANTED|PG_BUSY); 1531 UVM_PAGE_OWN(uobjpage, NULL); 1532 1533 uvm_lock_pageq(); 1534 offset = uobjpage->offset; 1535 /* remove old page */ 1536 uvm_pagerealloc(uobjpage, NULL, 0); 1537 1538 /* 1539 * at this point we have absolutely no 1540 * control over uobjpage 1541 */ 1542 /* install new page */ 1543 uvm_pagerealloc(pg, uobj, offset); 1544 uvm_unlock_pageq(); 1545 1546 /* 1547 * done! loan is broken and "pg" is 1548 * PG_BUSY. it can now replace uobjpage. 1549 */ 1550 1551 uobjpage = pg; 1552 1553 } /* write fault case */ 1554 } /* if loan_count */ 1555 1556 } else { 1557 1558 /* 1559 * if we are going to promote the data to an anon we 1560 * allocate a blank anon here and plug it into our amap. 1561 */ 1562 #if DIAGNOSTIC 1563 if (amap == NULL) 1564 panic("uvm_fault: want to promote data, but no anon"); 1565 #endif 1566 1567 anon = uvm_analloc(); 1568 if (anon) { 1569 /* 1570 * The new anon is locked. 1571 * 1572 * In `Fill in data...' below, if 1573 * uobjpage == PGO_DONTCARE, we want 1574 * a zero'd, dirty page, so have 1575 * uvm_pagealloc() do that for us. 1576 */ 1577 pg = uvm_pagealloc(NULL, 0, anon, 1578 (uobjpage == PGO_DONTCARE) ? UVM_PGA_ZERO : 0); 1579 } 1580 1581 /* 1582 * out of memory resources? 1583 */ 1584 if (anon == NULL || pg == NULL) { 1585 1586 if (anon != NULL) { 1587 anon->an_ref--; 1588 simple_unlock(&anon->an_lock); 1589 uvm_anfree(anon); 1590 } 1591 1592 /* 1593 * arg! must unbusy our page and fail or sleep. 1594 */ 1595 if (uobjpage != PGO_DONTCARE) { 1596 if (uobjpage->flags & PG_WANTED) 1597 /* still holding object lock */ 1598 wakeup(uobjpage); 1599 1600 uvm_lock_pageq(); 1601 uvm_pageactivate(uobjpage); 1602 uvm_unlock_pageq(); 1603 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1604 UVM_PAGE_OWN(uobjpage, NULL); 1605 } 1606 1607 /* unlock and fail ... */ 1608 uvmfault_unlockall(&ufi, amap, uobj, NULL); 1609 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 1610 if (anon == NULL || uvmexp.swpgonly == uvmexp.swpages) { 1611 UVMHIST_LOG(maphist, " promote: out of VM", 1612 0,0,0,0); 1613 uvmexp.fltnoanon++; 1614 return ENOMEM; 1615 } 1616 1617 UVMHIST_LOG(maphist, " out of RAM, waiting for more", 1618 0,0,0,0); 1619 uvmexp.fltnoram++; 1620 uvm_wait("flt_noram5"); 1621 goto ReFault; 1622 } 1623 1624 /* 1625 * fill in the data 1626 */ 1627 1628 if (uobjpage != PGO_DONTCARE) { 1629 uvmexp.flt_prcopy++; 1630 /* copy page [pg now dirty] */ 1631 uvm_pagecopy(uobjpage, pg); 1632 1633 /* 1634 * promote to shared amap? make sure all sharing 1635 * procs see it 1636 */ 1637 if ((amap_flags(amap) & AMAP_SHARED) != 0) { 1638 pmap_page_protect(uobjpage, VM_PROT_NONE); 1639 /* 1640 * XXX: PAGE MIGHT BE WIRED! 1641 */ 1642 } 1643 1644 /* 1645 * dispose of uobjpage. it can't be PG_RELEASED 1646 * since we still hold the object lock. 1647 * drop handle to uobj as well. 1648 */ 1649 1650 if (uobjpage->flags & PG_WANTED) 1651 /* still have the obj lock */ 1652 wakeup(uobjpage); 1653 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1654 UVM_PAGE_OWN(uobjpage, NULL); 1655 uvm_lock_pageq(); 1656 uvm_pageactivate(uobjpage); 1657 uvm_unlock_pageq(); 1658 simple_unlock(&uobj->vmobjlock); 1659 uobj = NULL; 1660 1661 UVMHIST_LOG(maphist, 1662 " promote uobjpage 0x%x to anon/page 0x%x/0x%x", 1663 uobjpage, anon, pg, 0); 1664 1665 } else { 1666 uvmexp.flt_przero++; 1667 /* 1668 * Page is zero'd and marked dirty by uvm_pagealloc() 1669 * above. 1670 */ 1671 UVMHIST_LOG(maphist," zero fill anon/page 0x%x/0%x", 1672 anon, pg, 0, 0); 1673 } 1674 1675 amap_add(&ufi.entry->aref, ufi.orig_rvaddr - ufi.entry->start, 1676 anon, 0); 1677 } 1678 1679 /* 1680 * locked: 1681 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj), 1682 * anon(if !null), pg(if anon) 1683 * 1684 * note: pg is either the uobjpage or the new page in the new anon 1685 */ 1686 1687 /* 1688 * all resources are present. we can now map it in and free our 1689 * resources. 1690 */ 1691 1692 UVMHIST_LOG(maphist, 1693 " MAPPING: case2: pm=0x%x, va=0x%x, pg=0x%x, promote=%d", 1694 ufi.orig_map->pmap, ufi.orig_rvaddr, pg, promote); 1695 KASSERT(access_type == VM_PROT_READ || (pg->flags & PG_RDONLY) == 0); 1696 if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg), 1697 pg->flags & PG_RDONLY ? VM_PROT_READ : enter_prot, 1698 access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0)) != 0) { 1699 1700 /* 1701 * No need to undo what we did; we can simply think of 1702 * this as the pmap throwing away the mapping information. 1703 * 1704 * We do, however, have to go through the ReFault path, 1705 * as the map may change while we're asleep. 1706 */ 1707 1708 if (pg->flags & PG_WANTED) 1709 wakeup(pg); /* lock still held */ 1710 1711 /* 1712 * note that pg can't be PG_RELEASED since we did not drop 1713 * the object lock since the last time we checked. 1714 */ 1715 1716 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 1717 UVM_PAGE_OWN(pg, NULL); 1718 uvmfault_unlockall(&ufi, amap, uobj, anon); 1719 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 1720 if (uvmexp.swpgonly == uvmexp.swpages) { 1721 UVMHIST_LOG(maphist, 1722 "<- failed. out of VM",0,0,0,0); 1723 /* XXX instrumentation */ 1724 return ENOMEM; 1725 } 1726 /* XXX instrumentation */ 1727 uvm_wait("flt_pmfail2"); 1728 goto ReFault; 1729 } 1730 1731 uvm_lock_pageq(); 1732 1733 if (fault_type == VM_FAULT_WIRE) { 1734 uvm_pagewire(pg); 1735 if (pg->pqflags & PQ_AOBJ) { 1736 1737 /* 1738 * since the now-wired page cannot be paged out, 1739 * release its swap resources for others to use. 1740 * since an aobj page with no swap cannot be PG_CLEAN, 1741 * clear its clean flag now. 1742 */ 1743 1744 pg->flags &= ~(PG_CLEAN); 1745 uao_dropswap(uobj, pg->offset >> PAGE_SHIFT); 1746 } 1747 } else { 1748 /* activate it */ 1749 uvm_pageactivate(pg); 1750 } 1751 uvm_unlock_pageq(); 1752 1753 if (pg->flags & PG_WANTED) 1754 wakeup(pg); /* lock still held */ 1755 1756 /* 1757 * note that pg can't be PG_RELEASED since we did not drop the object 1758 * lock since the last time we checked. 1759 */ 1760 1761 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 1762 UVM_PAGE_OWN(pg, NULL); 1763 uvmfault_unlockall(&ufi, amap, uobj, anon); 1764 1765 pmap_update(); 1766 1767 UVMHIST_LOG(maphist, "<- done (SUCCESS!)",0,0,0,0); 1768 return 0; 1769 } 1770 1771 1772 /* 1773 * uvm_fault_wire: wire down a range of virtual addresses in a map. 1774 * 1775 * => map may be read-locked by caller, but MUST NOT be write-locked. 1776 * => if map is read-locked, any operations which may cause map to 1777 * be write-locked in uvm_fault() must be taken care of by 1778 * the caller. See uvm_map_pageable(). 1779 */ 1780 1781 int 1782 uvm_fault_wire(map, start, end, access_type) 1783 struct vm_map *map; 1784 vaddr_t start, end; 1785 vm_prot_t access_type; 1786 { 1787 vaddr_t va; 1788 int error; 1789 1790 /* 1791 * now fault it in a page at a time. if the fault fails then we have 1792 * to undo what we have done. note that in uvm_fault VM_PROT_NONE 1793 * is replaced with the max protection if fault_type is VM_FAULT_WIRE. 1794 */ 1795 1796 /* 1797 * XXX work around overflowing a vaddr_t. this prevents us from 1798 * wiring the last page in the address space, though. 1799 */ 1800 if (start > end) { 1801 return EFAULT; 1802 } 1803 1804 for (va = start ; va < end ; va += PAGE_SIZE) { 1805 error = uvm_fault(map, va, VM_FAULT_WIRE, access_type); 1806 if (error) { 1807 if (va != start) { 1808 uvm_fault_unwire(map, start, va); 1809 } 1810 return error; 1811 } 1812 } 1813 return 0; 1814 } 1815 1816 /* 1817 * uvm_fault_unwire(): unwire range of virtual space. 1818 */ 1819 1820 void 1821 uvm_fault_unwire(map, start, end) 1822 struct vm_map *map; 1823 vaddr_t start, end; 1824 { 1825 1826 vm_map_lock_read(map); 1827 uvm_fault_unwire_locked(map, start, end); 1828 vm_map_unlock_read(map); 1829 } 1830 1831 /* 1832 * uvm_fault_unwire_locked(): the guts of uvm_fault_unwire(). 1833 * 1834 * => map must be at least read-locked. 1835 */ 1836 1837 void 1838 uvm_fault_unwire_locked(map, start, end) 1839 struct vm_map *map; 1840 vaddr_t start, end; 1841 { 1842 struct vm_map_entry *entry; 1843 pmap_t pmap = vm_map_pmap(map); 1844 vaddr_t va; 1845 paddr_t pa; 1846 struct vm_page *pg; 1847 1848 KASSERT((map->flags & VM_MAP_INTRSAFE) == 0); 1849 1850 /* 1851 * we assume that the area we are unwiring has actually been wired 1852 * in the first place. this means that we should be able to extract 1853 * the PAs from the pmap. we also lock out the page daemon so that 1854 * we can call uvm_pageunwire. 1855 */ 1856 1857 uvm_lock_pageq(); 1858 1859 /* 1860 * find the beginning map entry for the region. 1861 */ 1862 KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map)); 1863 if (uvm_map_lookup_entry(map, start, &entry) == FALSE) 1864 panic("uvm_fault_unwire_locked: address not in map"); 1865 1866 for (va = start; va < end ; va += PAGE_SIZE) { 1867 if (pmap_extract(pmap, va, &pa) == FALSE) 1868 panic("uvm_fault_unwire_locked: unwiring " 1869 "non-wired memory"); 1870 1871 /* 1872 * make sure the current entry is for the address we're 1873 * dealing with. if not, grab the next entry. 1874 */ 1875 1876 KASSERT(va >= entry->start); 1877 if (va >= entry->end) { 1878 KASSERT(entry->next != &map->header && 1879 entry->next->start <= entry->end); 1880 entry = entry->next; 1881 } 1882 1883 /* 1884 * if the entry is no longer wired, tell the pmap. 1885 */ 1886 if (VM_MAPENT_ISWIRED(entry) == 0) 1887 pmap_unwire(pmap, va); 1888 1889 pg = PHYS_TO_VM_PAGE(pa); 1890 if (pg) 1891 uvm_pageunwire(pg); 1892 } 1893 1894 uvm_unlock_pageq(); 1895 } 1896