1 /* $NetBSD: uvm_fault.c,v 1.84 2003/08/11 16:45:43 pk 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 /* 38 * uvm_fault.c: fault handler 39 */ 40 41 #include <sys/cdefs.h> 42 __KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.84 2003/08/11 16:45:43 pk Exp $"); 43 44 #include "opt_uvmhist.h" 45 46 #include <sys/param.h> 47 #include <sys/systm.h> 48 #include <sys/kernel.h> 49 #include <sys/proc.h> 50 #include <sys/malloc.h> 51 #include <sys/mman.h> 52 #include <sys/user.h> 53 54 #include <uvm/uvm.h> 55 56 /* 57 * 58 * a word on page faults: 59 * 60 * types of page faults we handle: 61 * 62 * CASE 1: upper layer faults CASE 2: lower layer faults 63 * 64 * CASE 1A CASE 1B CASE 2A CASE 2B 65 * read/write1 write>1 read/write +-cow_write/zero 66 * | | | | 67 * +--|--+ +--|--+ +-----+ + | + | +-----+ 68 * amap | V | | ----------->new| | | | ^ | 69 * +-----+ +-----+ +-----+ + | + | +--|--+ 70 * | | | 71 * +-----+ +-----+ +--|--+ | +--|--+ 72 * uobj | d/c | | d/c | | V | +----| | 73 * +-----+ +-----+ +-----+ +-----+ 74 * 75 * d/c = don't care 76 * 77 * case [0]: layerless fault 78 * no amap or uobj is present. this is an error. 79 * 80 * case [1]: upper layer fault [anon active] 81 * 1A: [read] or [write with anon->an_ref == 1] 82 * I/O takes place in top level anon and uobj is not touched. 83 * 1B: [write with anon->an_ref > 1] 84 * new anon is alloc'd and data is copied off ["COW"] 85 * 86 * case [2]: lower layer fault [uobj] 87 * 2A: [read on non-NULL uobj] or [write to non-copy_on_write area] 88 * I/O takes place directly in object. 89 * 2B: [write to copy_on_write] or [read on NULL uobj] 90 * data is "promoted" from uobj to a new anon. 91 * if uobj is null, then we zero fill. 92 * 93 * we follow the standard UVM locking protocol ordering: 94 * 95 * MAPS => AMAP => UOBJ => ANON => PAGE QUEUES (PQ) 96 * we hold a PG_BUSY page if we unlock for I/O 97 * 98 * 99 * the code is structured as follows: 100 * 101 * - init the "IN" params in the ufi structure 102 * ReFault: 103 * - do lookups [locks maps], check protection, handle needs_copy 104 * - check for case 0 fault (error) 105 * - establish "range" of fault 106 * - if we have an amap lock it and extract the anons 107 * - if sequential advice deactivate pages behind us 108 * - at the same time check pmap for unmapped areas and anon for pages 109 * that we could map in (and do map it if found) 110 * - check object for resident pages that we could map in 111 * - if (case 2) goto Case2 112 * - >>> handle case 1 113 * - ensure source anon is resident in RAM 114 * - if case 1B alloc new anon and copy from source 115 * - map the correct page in 116 * Case2: 117 * - >>> handle case 2 118 * - ensure source page is resident (if uobj) 119 * - if case 2B alloc new anon and copy from source (could be zero 120 * fill if uobj == NULL) 121 * - map the correct page in 122 * - done! 123 * 124 * note on paging: 125 * if we have to do I/O we place a PG_BUSY page in the correct object, 126 * unlock everything, and do the I/O. when I/O is done we must reverify 127 * the state of the world before assuming that our data structures are 128 * valid. [because mappings could change while the map is unlocked] 129 * 130 * alternative 1: unbusy the page in question and restart the page fault 131 * from the top (ReFault). this is easy but does not take advantage 132 * of the information that we already have from our previous lookup, 133 * although it is possible that the "hints" in the vm_map will help here. 134 * 135 * alternative 2: the system already keeps track of a "version" number of 136 * a map. [i.e. every time you write-lock a map (e.g. to change a 137 * mapping) you bump the version number up by one...] so, we can save 138 * the version number of the map before we release the lock and start I/O. 139 * then when I/O is done we can relock and check the version numbers 140 * to see if anything changed. this might save us some over 1 because 141 * we don't have to unbusy the page and may be less compares(?). 142 * 143 * alternative 3: put in backpointers or a way to "hold" part of a map 144 * in place while I/O is in progress. this could be complex to 145 * implement (especially with structures like amap that can be referenced 146 * by multiple map entries, and figuring out what should wait could be 147 * complex as well...). 148 * 149 * given that we are not currently multiprocessor or multithreaded we might 150 * as well choose alternative 2 now. maybe alternative 3 would be useful 151 * in the future. XXX keep in mind for future consideration//rechecking. 152 */ 153 154 /* 155 * local data structures 156 */ 157 158 struct uvm_advice { 159 int advice; 160 int nback; 161 int nforw; 162 }; 163 164 /* 165 * page range array: 166 * note: index in array must match "advice" value 167 * XXX: borrowed numbers from freebsd. do they work well for us? 168 */ 169 170 static struct uvm_advice uvmadvice[] = { 171 { MADV_NORMAL, 3, 4 }, 172 { MADV_RANDOM, 0, 0 }, 173 { MADV_SEQUENTIAL, 8, 7}, 174 }; 175 176 #define UVM_MAXRANGE 16 /* must be MAX() of nback+nforw+1 */ 177 178 /* 179 * private prototypes 180 */ 181 182 static void uvmfault_amapcopy __P((struct uvm_faultinfo *)); 183 static __inline void uvmfault_anonflush __P((struct vm_anon **, int)); 184 185 /* 186 * inline functions 187 */ 188 189 /* 190 * uvmfault_anonflush: try and deactivate pages in specified anons 191 * 192 * => does not have to deactivate page if it is busy 193 */ 194 195 static __inline void 196 uvmfault_anonflush(anons, n) 197 struct vm_anon **anons; 198 int n; 199 { 200 int lcv; 201 struct vm_page *pg; 202 203 for (lcv = 0 ; lcv < n ; lcv++) { 204 if (anons[lcv] == NULL) 205 continue; 206 simple_lock(&anons[lcv]->an_lock); 207 pg = anons[lcv]->u.an_page; 208 if (pg && (pg->flags & PG_BUSY) == 0 && pg->loan_count == 0) { 209 uvm_lock_pageq(); 210 if (pg->wire_count == 0) { 211 pmap_clear_reference(pg); 212 uvm_pagedeactivate(pg); 213 } 214 uvm_unlock_pageq(); 215 } 216 simple_unlock(&anons[lcv]->an_lock); 217 } 218 } 219 220 /* 221 * normal functions 222 */ 223 224 /* 225 * uvmfault_amapcopy: clear "needs_copy" in a map. 226 * 227 * => called with VM data structures unlocked (usually, see below) 228 * => we get a write lock on the maps and clear needs_copy for a VA 229 * => if we are out of RAM we sleep (waiting for more) 230 */ 231 232 static void 233 uvmfault_amapcopy(ufi) 234 struct uvm_faultinfo *ufi; 235 { 236 for (;;) { 237 238 /* 239 * no mapping? give up. 240 */ 241 242 if (uvmfault_lookup(ufi, TRUE) == FALSE) 243 return; 244 245 /* 246 * copy if needed. 247 */ 248 249 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) 250 amap_copy(ufi->map, ufi->entry, M_NOWAIT, TRUE, 251 ufi->orig_rvaddr, ufi->orig_rvaddr + 1); 252 253 /* 254 * didn't work? must be out of RAM. unlock and sleep. 255 */ 256 257 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 258 uvmfault_unlockmaps(ufi, TRUE); 259 uvm_wait("fltamapcopy"); 260 continue; 261 } 262 263 /* 264 * got it! unlock and return. 265 */ 266 267 uvmfault_unlockmaps(ufi, TRUE); 268 return; 269 } 270 /*NOTREACHED*/ 271 } 272 273 /* 274 * uvmfault_anonget: get data in an anon into a non-busy, non-released 275 * page in that anon. 276 * 277 * => maps, amap, and anon locked by caller. 278 * => if we fail (result != 0) we unlock everything. 279 * => if we are successful, we return with everything still locked. 280 * => we don't move the page on the queues [gets moved later] 281 * => if we allocate a new page [we_own], it gets put on the queues. 282 * either way, the result is that the page is on the queues at return time 283 * => for pages which are on loan from a uvm_object (and thus are not 284 * owned by the anon): if successful, we return with the owning object 285 * locked. the caller must unlock this object when it unlocks everything 286 * else. 287 */ 288 289 int 290 uvmfault_anonget(ufi, amap, anon) 291 struct uvm_faultinfo *ufi; 292 struct vm_amap *amap; 293 struct vm_anon *anon; 294 { 295 boolean_t we_own; /* we own anon's page? */ 296 boolean_t locked; /* did we relock? */ 297 struct vm_page *pg; 298 int error; 299 UVMHIST_FUNC("uvmfault_anonget"); UVMHIST_CALLED(maphist); 300 301 LOCK_ASSERT(simple_lock_held(&anon->an_lock)); 302 303 error = 0; 304 uvmexp.fltanget++; 305 /* bump rusage counters */ 306 if (anon->u.an_page) 307 curproc->p_stats->p_ru.ru_minflt++; 308 else 309 curproc->p_stats->p_ru.ru_majflt++; 310 311 /* 312 * loop until we get it, or fail. 313 */ 314 315 for (;;) { 316 we_own = FALSE; /* TRUE if we set PG_BUSY on a page */ 317 pg = anon->u.an_page; 318 319 /* 320 * if there is a resident page and it is loaned, then anon 321 * may not own it. call out to uvm_anon_lockpage() to ensure 322 * the real owner of the page has been identified and locked. 323 */ 324 325 if (pg && pg->loan_count) 326 pg = uvm_anon_lockloanpg(anon); 327 328 /* 329 * page there? make sure it is not busy/released. 330 */ 331 332 if (pg) { 333 334 /* 335 * at this point, if the page has a uobject [meaning 336 * we have it on loan], then that uobject is locked 337 * by us! if the page is busy, we drop all the 338 * locks (including uobject) and try again. 339 */ 340 341 if ((pg->flags & PG_BUSY) == 0) { 342 UVMHIST_LOG(maphist, "<- OK",0,0,0,0); 343 return (0); 344 } 345 pg->flags |= PG_WANTED; 346 uvmexp.fltpgwait++; 347 348 /* 349 * the last unlock must be an atomic unlock+wait on 350 * the owner of page 351 */ 352 353 if (pg->uobject) { /* owner is uobject ? */ 354 uvmfault_unlockall(ufi, amap, NULL, anon); 355 UVMHIST_LOG(maphist, " unlock+wait on uobj",0, 356 0,0,0); 357 UVM_UNLOCK_AND_WAIT(pg, 358 &pg->uobject->vmobjlock, 359 FALSE, "anonget1",0); 360 } else { 361 /* anon owns page */ 362 uvmfault_unlockall(ufi, amap, NULL, NULL); 363 UVMHIST_LOG(maphist, " unlock+wait on anon",0, 364 0,0,0); 365 UVM_UNLOCK_AND_WAIT(pg,&anon->an_lock,0, 366 "anonget2",0); 367 } 368 } else { 369 370 /* 371 * no page, we must try and bring it in. 372 */ 373 374 pg = uvm_pagealloc(NULL, 0, anon, 0); 375 if (pg == NULL) { /* out of RAM. */ 376 uvmfault_unlockall(ufi, amap, NULL, anon); 377 uvmexp.fltnoram++; 378 UVMHIST_LOG(maphist, " noram -- UVM_WAIT",0, 379 0,0,0); 380 uvm_wait("flt_noram1"); 381 } else { 382 /* we set the PG_BUSY bit */ 383 we_own = TRUE; 384 uvmfault_unlockall(ufi, amap, NULL, anon); 385 386 /* 387 * we are passing a PG_BUSY+PG_FAKE+PG_CLEAN 388 * page into the uvm_swap_get function with 389 * all data structures unlocked. note that 390 * it is ok to read an_swslot here because 391 * we hold PG_BUSY on the page. 392 */ 393 uvmexp.pageins++; 394 error = uvm_swap_get(pg, anon->an_swslot, 395 PGO_SYNCIO); 396 397 /* 398 * we clean up after the i/o below in the 399 * "we_own" case 400 */ 401 } 402 } 403 404 /* 405 * now relock and try again 406 */ 407 408 locked = uvmfault_relock(ufi); 409 if (locked && amap != NULL) { 410 amap_lock(amap); 411 } 412 if (locked || we_own) 413 simple_lock(&anon->an_lock); 414 415 /* 416 * if we own the page (i.e. we set PG_BUSY), then we need 417 * to clean up after the I/O. there are three cases to 418 * consider: 419 * [1] page released during I/O: free anon and ReFault. 420 * [2] I/O not OK. free the page and cause the fault 421 * to fail. 422 * [3] I/O OK! activate the page and sync with the 423 * non-we_own case (i.e. drop anon lock if not locked). 424 */ 425 426 if (we_own) { 427 if (pg->flags & PG_WANTED) { 428 wakeup(pg); 429 } 430 if (error) { 431 /* remove page from anon */ 432 anon->u.an_page = NULL; 433 434 /* 435 * remove the swap slot from the anon 436 * and mark the anon as having no real slot. 437 * don't free the swap slot, thus preventing 438 * it from being used again. 439 */ 440 441 if (anon->an_swslot > 0) 442 uvm_swap_markbad(anon->an_swslot, 1); 443 anon->an_swslot = SWSLOT_BAD; 444 445 /* 446 * note: page was never !PG_BUSY, so it 447 * can't be mapped and thus no need to 448 * pmap_page_protect it... 449 */ 450 451 uvm_lock_pageq(); 452 uvm_pagefree(pg); 453 uvm_unlock_pageq(); 454 455 if (locked) 456 uvmfault_unlockall(ufi, amap, NULL, 457 anon); 458 else 459 simple_unlock(&anon->an_lock); 460 UVMHIST_LOG(maphist, "<- ERROR", 0,0,0,0); 461 return error; 462 } 463 464 /* 465 * we've successfully read the page, activate it. 466 */ 467 468 uvm_lock_pageq(); 469 uvm_pageactivate(pg); 470 uvm_unlock_pageq(); 471 pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE); 472 UVM_PAGE_OWN(pg, NULL); 473 if (!locked) 474 simple_unlock(&anon->an_lock); 475 } 476 477 /* 478 * we were not able to relock. restart fault. 479 */ 480 481 if (!locked) { 482 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 483 return (ERESTART); 484 } 485 486 /* 487 * verify no one has touched the amap and moved the anon on us. 488 */ 489 490 if (ufi != NULL && 491 amap_lookup(&ufi->entry->aref, 492 ufi->orig_rvaddr - ufi->entry->start) != anon) { 493 494 uvmfault_unlockall(ufi, amap, NULL, anon); 495 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 496 return (ERESTART); 497 } 498 499 /* 500 * try it again! 501 */ 502 503 uvmexp.fltanretry++; 504 continue; 505 } 506 /*NOTREACHED*/ 507 } 508 509 /* 510 * F A U L T - m a i n e n t r y p o i n t 511 */ 512 513 /* 514 * uvm_fault: page fault handler 515 * 516 * => called from MD code to resolve a page fault 517 * => VM data structures usually should be unlocked. however, it is 518 * possible to call here with the main map locked if the caller 519 * gets a write lock, sets it recusive, and then calls us (c.f. 520 * uvm_map_pageable). this should be avoided because it keeps 521 * the map locked off during I/O. 522 * => MUST NEVER BE CALLED IN INTERRUPT CONTEXT 523 */ 524 525 #define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \ 526 ~VM_PROT_WRITE : VM_PROT_ALL) 527 528 int 529 uvm_fault(orig_map, vaddr, fault_type, access_type) 530 struct vm_map *orig_map; 531 vaddr_t vaddr; 532 vm_fault_t fault_type; 533 vm_prot_t access_type; 534 { 535 struct uvm_faultinfo ufi; 536 vm_prot_t enter_prot, check_prot; 537 boolean_t wired, narrow, promote, locked, shadowed, wire_fault, cow_now; 538 int npages, nback, nforw, centeridx, error, lcv, gotpages; 539 vaddr_t startva, objaddr, currva; 540 voff_t uoff; 541 paddr_t pa; 542 struct vm_amap *amap; 543 struct uvm_object *uobj; 544 struct vm_anon *anons_store[UVM_MAXRANGE], **anons, *anon, *oanon; 545 struct vm_page *pages[UVM_MAXRANGE], *pg, *uobjpage; 546 UVMHIST_FUNC("uvm_fault"); UVMHIST_CALLED(maphist); 547 548 UVMHIST_LOG(maphist, "(map=0x%x, vaddr=0x%x, ft=%d, at=%d)", 549 orig_map, vaddr, fault_type, access_type); 550 551 anon = NULL; 552 pg = NULL; 553 554 uvmexp.faults++; /* XXX: locking? */ 555 556 /* 557 * init the IN parameters in the ufi 558 */ 559 560 ufi.orig_map = orig_map; 561 ufi.orig_rvaddr = trunc_page(vaddr); 562 ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */ 563 wire_fault = fault_type == VM_FAULT_WIRE || 564 fault_type == VM_FAULT_WIREMAX; 565 if (wire_fault) 566 narrow = TRUE; /* don't look for neighborhood 567 * pages on wire */ 568 else 569 narrow = FALSE; /* normal fault */ 570 571 /* 572 * "goto ReFault" means restart the page fault from ground zero. 573 */ 574 ReFault: 575 576 /* 577 * lookup and lock the maps 578 */ 579 580 if (uvmfault_lookup(&ufi, FALSE) == FALSE) { 581 UVMHIST_LOG(maphist, "<- no mapping @ 0x%x", vaddr, 0,0,0); 582 return (EFAULT); 583 } 584 /* locked: maps(read) */ 585 586 #ifdef DIAGNOSTIC 587 if ((ufi.map->flags & VM_MAP_PAGEABLE) == 0) { 588 printf("Page fault on non-pageable map:\n"); 589 printf("ufi.map = %p\n", ufi.map); 590 printf("ufi.orig_map = %p\n", ufi.orig_map); 591 printf("ufi.orig_rvaddr = 0x%lx\n", (u_long) ufi.orig_rvaddr); 592 panic("uvm_fault: (ufi.map->flags & VM_MAP_PAGEABLE) == 0"); 593 } 594 #endif 595 596 /* 597 * check protection 598 */ 599 600 check_prot = fault_type == VM_FAULT_WIREMAX ? 601 ufi.entry->max_protection : ufi.entry->protection; 602 if ((check_prot & access_type) != access_type) { 603 UVMHIST_LOG(maphist, 604 "<- protection failure (prot=0x%x, access=0x%x)", 605 ufi.entry->protection, access_type, 0, 0); 606 uvmfault_unlockmaps(&ufi, FALSE); 607 return EACCES; 608 } 609 610 /* 611 * "enter_prot" is the protection we want to enter the page in at. 612 * for certain pages (e.g. copy-on-write pages) this protection can 613 * be more strict than ufi.entry->protection. "wired" means either 614 * the entry is wired or we are fault-wiring the pg. 615 */ 616 617 enter_prot = ufi.entry->protection; 618 wired = VM_MAPENT_ISWIRED(ufi.entry) || wire_fault; 619 if (wired) { 620 access_type = enter_prot; /* full access for wired */ 621 cow_now = (check_prot & VM_PROT_WRITE) != 0; 622 } else { 623 cow_now = (access_type & VM_PROT_WRITE) != 0; 624 } 625 626 /* 627 * handle "needs_copy" case. if we need to copy the amap we will 628 * have to drop our readlock and relock it with a write lock. (we 629 * need a write lock to change anything in a map entry [e.g. 630 * needs_copy]). 631 */ 632 633 if (UVM_ET_ISNEEDSCOPY(ufi.entry)) { 634 KASSERT(fault_type != VM_FAULT_WIREMAX); 635 if (cow_now || (ufi.entry->object.uvm_obj == NULL)) { 636 /* need to clear */ 637 UVMHIST_LOG(maphist, 638 " need to clear needs_copy and refault",0,0,0,0); 639 uvmfault_unlockmaps(&ufi, FALSE); 640 uvmfault_amapcopy(&ufi); 641 uvmexp.fltamcopy++; 642 goto ReFault; 643 644 } else { 645 646 /* 647 * ensure that we pmap_enter page R/O since 648 * needs_copy is still true 649 */ 650 651 enter_prot &= ~VM_PROT_WRITE; 652 } 653 } 654 655 /* 656 * identify the players 657 */ 658 659 amap = ufi.entry->aref.ar_amap; /* top layer */ 660 uobj = ufi.entry->object.uvm_obj; /* bottom layer */ 661 662 /* 663 * check for a case 0 fault. if nothing backing the entry then 664 * error now. 665 */ 666 667 if (amap == NULL && uobj == NULL) { 668 uvmfault_unlockmaps(&ufi, FALSE); 669 UVMHIST_LOG(maphist,"<- no backing store, no overlay",0,0,0,0); 670 return (EFAULT); 671 } 672 673 /* 674 * establish range of interest based on advice from mapper 675 * and then clip to fit map entry. note that we only want 676 * to do this the first time through the fault. if we 677 * ReFault we will disable this by setting "narrow" to true. 678 */ 679 680 if (narrow == FALSE) { 681 682 /* wide fault (!narrow) */ 683 KASSERT(uvmadvice[ufi.entry->advice].advice == 684 ufi.entry->advice); 685 nback = MIN(uvmadvice[ufi.entry->advice].nback, 686 (ufi.orig_rvaddr - ufi.entry->start) >> PAGE_SHIFT); 687 startva = ufi.orig_rvaddr - (nback << PAGE_SHIFT); 688 nforw = MIN(uvmadvice[ufi.entry->advice].nforw, 689 ((ufi.entry->end - ufi.orig_rvaddr) >> 690 PAGE_SHIFT) - 1); 691 /* 692 * note: "-1" because we don't want to count the 693 * faulting page as forw 694 */ 695 npages = nback + nforw + 1; 696 centeridx = nback; 697 698 narrow = TRUE; /* ensure only once per-fault */ 699 700 } else { 701 702 /* narrow fault! */ 703 nback = nforw = 0; 704 startva = ufi.orig_rvaddr; 705 npages = 1; 706 centeridx = 0; 707 708 } 709 710 /* locked: maps(read) */ 711 UVMHIST_LOG(maphist, " narrow=%d, back=%d, forw=%d, startva=0x%x", 712 narrow, nback, nforw, startva); 713 UVMHIST_LOG(maphist, " entry=0x%x, amap=0x%x, obj=0x%x", ufi.entry, 714 amap, uobj, 0); 715 716 /* 717 * if we've got an amap, lock it and extract current anons. 718 */ 719 720 if (amap) { 721 amap_lock(amap); 722 anons = anons_store; 723 amap_lookups(&ufi.entry->aref, startva - ufi.entry->start, 724 anons, npages); 725 } else { 726 anons = NULL; /* to be safe */ 727 } 728 729 /* locked: maps(read), amap(if there) */ 730 731 /* 732 * for MADV_SEQUENTIAL mappings we want to deactivate the back pages 733 * now and then forget about them (for the rest of the fault). 734 */ 735 736 if (ufi.entry->advice == MADV_SEQUENTIAL && nback != 0) { 737 738 UVMHIST_LOG(maphist, " MADV_SEQUENTIAL: flushing backpages", 739 0,0,0,0); 740 /* flush back-page anons? */ 741 if (amap) 742 uvmfault_anonflush(anons, nback); 743 744 /* flush object? */ 745 if (uobj) { 746 objaddr = 747 (startva - ufi.entry->start) + ufi.entry->offset; 748 simple_lock(&uobj->vmobjlock); 749 (void) (uobj->pgops->pgo_put)(uobj, objaddr, objaddr + 750 (nback << PAGE_SHIFT), PGO_DEACTIVATE); 751 } 752 753 /* now forget about the backpages */ 754 if (amap) 755 anons += nback; 756 startva += (nback << PAGE_SHIFT); 757 npages -= nback; 758 nback = centeridx = 0; 759 } 760 761 /* locked: maps(read), amap(if there) */ 762 763 /* 764 * map in the backpages and frontpages we found in the amap in hopes 765 * of preventing future faults. we also init the pages[] array as 766 * we go. 767 */ 768 769 currva = startva; 770 shadowed = FALSE; 771 for (lcv = 0 ; lcv < npages ; lcv++, currva += PAGE_SIZE) { 772 773 /* 774 * dont play with VAs that are already mapped 775 * except for center) 776 */ 777 if (lcv != centeridx && 778 pmap_extract(ufi.orig_map->pmap, currva, &pa)) { 779 pages[lcv] = PGO_DONTCARE; 780 continue; 781 } 782 783 /* 784 * unmapped or center page. check if any anon at this level. 785 */ 786 if (amap == NULL || anons[lcv] == NULL) { 787 pages[lcv] = NULL; 788 continue; 789 } 790 791 /* 792 * check for present page and map if possible. re-activate it. 793 */ 794 795 pages[lcv] = PGO_DONTCARE; 796 if (lcv == centeridx) { /* save center for later! */ 797 shadowed = TRUE; 798 continue; 799 } 800 anon = anons[lcv]; 801 simple_lock(&anon->an_lock); 802 /* ignore loaned pages */ 803 if (anon->u.an_page && anon->u.an_page->loan_count == 0 && 804 (anon->u.an_page->flags & PG_BUSY) == 0) { 805 uvm_lock_pageq(); 806 uvm_pageactivate(anon->u.an_page); 807 uvm_unlock_pageq(); 808 UVMHIST_LOG(maphist, 809 " MAPPING: n anon: pm=0x%x, va=0x%x, pg=0x%x", 810 ufi.orig_map->pmap, currva, anon->u.an_page, 0); 811 uvmexp.fltnamap++; 812 813 /* 814 * Since this isn't the page that's actually faulting, 815 * ignore pmap_enter() failures; it's not critical 816 * that we enter these right now. 817 */ 818 819 (void) pmap_enter(ufi.orig_map->pmap, currva, 820 VM_PAGE_TO_PHYS(anon->u.an_page), 821 (anon->an_ref > 1) ? (enter_prot & ~VM_PROT_WRITE) : 822 enter_prot, 823 PMAP_CANFAIL | 824 (VM_MAPENT_ISWIRED(ufi.entry) ? PMAP_WIRED : 0)); 825 } 826 simple_unlock(&anon->an_lock); 827 pmap_update(ufi.orig_map->pmap); 828 } 829 830 /* locked: maps(read), amap(if there) */ 831 /* (shadowed == TRUE) if there is an anon at the faulting address */ 832 UVMHIST_LOG(maphist, " shadowed=%d, will_get=%d", shadowed, 833 (uobj && shadowed == FALSE),0,0); 834 835 /* 836 * note that if we are really short of RAM we could sleep in the above 837 * call to pmap_enter with everything locked. bad? 838 * 839 * XXX Actually, that is bad; pmap_enter() should just fail in that 840 * XXX case. --thorpej 841 */ 842 843 /* 844 * if the desired page is not shadowed by the amap and we have a 845 * backing object, then we check to see if the backing object would 846 * prefer to handle the fault itself (rather than letting us do it 847 * with the usual pgo_get hook). the backing object signals this by 848 * providing a pgo_fault routine. 849 */ 850 851 if (uobj && shadowed == FALSE && uobj->pgops->pgo_fault != NULL) { 852 simple_lock(&uobj->vmobjlock); 853 854 /* locked: maps(read), amap (if there), uobj */ 855 error = uobj->pgops->pgo_fault(&ufi, startva, pages, npages, 856 centeridx, fault_type, access_type, PGO_LOCKED|PGO_SYNCIO); 857 858 /* locked: nothing, pgo_fault has unlocked everything */ 859 860 if (error == ERESTART) 861 goto ReFault; /* try again! */ 862 /* 863 * object fault routine responsible for pmap_update(). 864 */ 865 return error; 866 } 867 868 /* 869 * now, if the desired page is not shadowed by the amap and we have 870 * a backing object that does not have a special fault routine, then 871 * we ask (with pgo_get) the object for resident pages that we care 872 * about and attempt to map them in. we do not let pgo_get block 873 * (PGO_LOCKED). 874 */ 875 876 if (uobj && shadowed == FALSE) { 877 simple_lock(&uobj->vmobjlock); 878 879 /* locked (!shadowed): maps(read), amap (if there), uobj */ 880 /* 881 * the following call to pgo_get does _not_ change locking state 882 */ 883 884 uvmexp.fltlget++; 885 gotpages = npages; 886 (void) uobj->pgops->pgo_get(uobj, ufi.entry->offset + 887 (startva - ufi.entry->start), 888 pages, &gotpages, centeridx, 889 access_type & MASK(ufi.entry), 890 ufi.entry->advice, PGO_LOCKED); 891 892 /* 893 * check for pages to map, if we got any 894 */ 895 896 uobjpage = NULL; 897 898 if (gotpages) { 899 currva = startva; 900 for (lcv = 0; lcv < npages; 901 lcv++, currva += PAGE_SIZE) { 902 if (pages[lcv] == NULL || 903 pages[lcv] == PGO_DONTCARE) { 904 continue; 905 } 906 907 /* 908 * if center page is resident and not 909 * PG_BUSY|PG_RELEASED then pgo_get 910 * made it PG_BUSY for us and gave 911 * us a handle to it. remember this 912 * page as "uobjpage." (for later use). 913 */ 914 915 if (lcv == centeridx) { 916 uobjpage = pages[lcv]; 917 UVMHIST_LOG(maphist, " got uobjpage " 918 "(0x%x) with locked get", 919 uobjpage, 0,0,0); 920 continue; 921 } 922 923 /* 924 * calling pgo_get with PGO_LOCKED returns us 925 * pages which are neither busy nor released, 926 * so we don't need to check for this. 927 * we can just directly enter the pages. 928 */ 929 930 uvm_lock_pageq(); 931 uvm_pageactivate(pages[lcv]); 932 uvm_unlock_pageq(); 933 UVMHIST_LOG(maphist, 934 " MAPPING: n obj: pm=0x%x, va=0x%x, pg=0x%x", 935 ufi.orig_map->pmap, currva, pages[lcv], 0); 936 uvmexp.fltnomap++; 937 938 /* 939 * Since this page isn't the page that's 940 * actually fauling, ignore pmap_enter() 941 * failures; it's not critical that we 942 * enter these right now. 943 */ 944 945 (void) pmap_enter(ufi.orig_map->pmap, currva, 946 VM_PAGE_TO_PHYS(pages[lcv]), 947 pages[lcv]->flags & PG_RDONLY ? 948 enter_prot & ~VM_PROT_WRITE : 949 enter_prot & MASK(ufi.entry), 950 PMAP_CANFAIL | 951 (wired ? PMAP_WIRED : 0)); 952 953 /* 954 * NOTE: page can't be PG_WANTED or PG_RELEASED 955 * because we've held the lock the whole time 956 * we've had the handle. 957 */ 958 959 pages[lcv]->flags &= ~(PG_BUSY); 960 UVM_PAGE_OWN(pages[lcv], NULL); 961 } 962 pmap_update(ufi.orig_map->pmap); 963 } 964 } else { 965 uobjpage = NULL; 966 } 967 968 /* locked (shadowed): maps(read), amap */ 969 /* locked (!shadowed): maps(read), amap(if there), 970 uobj(if !null), uobjpage(if !null) */ 971 972 /* 973 * note that at this point we are done with any front or back pages. 974 * we are now going to focus on the center page (i.e. the one we've 975 * faulted on). if we have faulted on the top (anon) layer 976 * [i.e. case 1], then the anon we want is anons[centeridx] (we have 977 * not touched it yet). if we have faulted on the bottom (uobj) 978 * layer [i.e. case 2] and the page was both present and available, 979 * then we've got a pointer to it as "uobjpage" and we've already 980 * made it BUSY. 981 */ 982 983 /* 984 * there are four possible cases we must address: 1A, 1B, 2A, and 2B 985 */ 986 987 /* 988 * redirect case 2: if we are not shadowed, go to case 2. 989 */ 990 991 if (shadowed == FALSE) 992 goto Case2; 993 994 /* locked: maps(read), amap */ 995 996 /* 997 * handle case 1: fault on an anon in our amap 998 */ 999 1000 anon = anons[centeridx]; 1001 UVMHIST_LOG(maphist, " case 1 fault: anon=0x%x", anon, 0,0,0); 1002 simple_lock(&anon->an_lock); 1003 1004 /* locked: maps(read), amap, anon */ 1005 1006 /* 1007 * no matter if we have case 1A or case 1B we are going to need to 1008 * have the anon's memory resident. ensure that now. 1009 */ 1010 1011 /* 1012 * let uvmfault_anonget do the dirty work. 1013 * if it fails (!OK) it will unlock everything for us. 1014 * if it succeeds, locks are still valid and locked. 1015 * also, if it is OK, then the anon's page is on the queues. 1016 * if the page is on loan from a uvm_object, then anonget will 1017 * lock that object for us if it does not fail. 1018 */ 1019 1020 error = uvmfault_anonget(&ufi, amap, anon); 1021 switch (error) { 1022 case 0: 1023 break; 1024 1025 case ERESTART: 1026 goto ReFault; 1027 1028 case EAGAIN: 1029 tsleep(&lbolt, PVM, "fltagain1", 0); 1030 goto ReFault; 1031 1032 default: 1033 return error; 1034 } 1035 1036 /* 1037 * uobj is non null if the page is on loan from an object (i.e. uobj) 1038 */ 1039 1040 uobj = anon->u.an_page->uobject; /* locked by anonget if !NULL */ 1041 1042 /* locked: maps(read), amap, anon, uobj(if one) */ 1043 1044 /* 1045 * special handling for loaned pages 1046 */ 1047 1048 if (anon->u.an_page->loan_count) { 1049 1050 if (!cow_now) { 1051 1052 /* 1053 * for read faults on loaned pages we just cap the 1054 * protection at read-only. 1055 */ 1056 1057 enter_prot = enter_prot & ~VM_PROT_WRITE; 1058 1059 } else { 1060 /* 1061 * note that we can't allow writes into a loaned page! 1062 * 1063 * if we have a write fault on a loaned page in an 1064 * anon then we need to look at the anon's ref count. 1065 * if it is greater than one then we are going to do 1066 * a normal copy-on-write fault into a new anon (this 1067 * is not a problem). however, if the reference count 1068 * is one (a case where we would normally allow a 1069 * write directly to the page) then we need to kill 1070 * the loan before we continue. 1071 */ 1072 1073 /* >1 case is already ok */ 1074 if (anon->an_ref == 1) { 1075 1076 /* get new un-owned replacement page */ 1077 pg = uvm_pagealloc(NULL, 0, NULL, 0); 1078 if (pg == NULL) { 1079 uvmfault_unlockall(&ufi, amap, uobj, 1080 anon); 1081 uvm_wait("flt_noram2"); 1082 goto ReFault; 1083 } 1084 1085 /* 1086 * copy data, kill loan, and drop uobj lock 1087 * (if any) 1088 */ 1089 /* copy old -> new */ 1090 uvm_pagecopy(anon->u.an_page, pg); 1091 1092 /* force reload */ 1093 pmap_page_protect(anon->u.an_page, 1094 VM_PROT_NONE); 1095 uvm_lock_pageq(); /* KILL loan */ 1096 1097 anon->u.an_page->uanon = NULL; 1098 /* in case we owned */ 1099 anon->u.an_page->pqflags &= ~PQ_ANON; 1100 1101 if (uobj) { 1102 /* if we were receiver of loan */ 1103 anon->u.an_page->loan_count--; 1104 } else { 1105 /* 1106 * we were the lender (A->K); need 1107 * to remove the page from pageq's. 1108 */ 1109 uvm_pagedequeue(anon->u.an_page); 1110 } 1111 1112 uvm_pageactivate(pg); 1113 uvm_unlock_pageq(); 1114 if (uobj) { 1115 simple_unlock(&uobj->vmobjlock); 1116 uobj = NULL; 1117 } 1118 1119 /* install new page in anon */ 1120 anon->u.an_page = pg; 1121 pg->uanon = anon; 1122 pg->pqflags |= PQ_ANON; 1123 pg->flags &= ~(PG_BUSY|PG_FAKE); 1124 UVM_PAGE_OWN(pg, NULL); 1125 1126 /* done! */ 1127 } /* ref == 1 */ 1128 } /* write fault */ 1129 } /* loan count */ 1130 1131 /* 1132 * if we are case 1B then we will need to allocate a new blank 1133 * anon to transfer the data into. note that we have a lock 1134 * on anon, so no one can busy or release the page until we are done. 1135 * also note that the ref count can't drop to zero here because 1136 * it is > 1 and we are only dropping one ref. 1137 * 1138 * in the (hopefully very rare) case that we are out of RAM we 1139 * will unlock, wait for more RAM, and refault. 1140 * 1141 * if we are out of anon VM we kill the process (XXX: could wait?). 1142 */ 1143 1144 if (cow_now && anon->an_ref > 1) { 1145 1146 UVMHIST_LOG(maphist, " case 1B: COW fault",0,0,0,0); 1147 uvmexp.flt_acow++; 1148 oanon = anon; /* oanon = old, locked anon */ 1149 anon = uvm_analloc(); 1150 if (anon) { 1151 /* new anon is locked! */ 1152 pg = uvm_pagealloc(NULL, 0, anon, 0); 1153 } 1154 1155 /* check for out of RAM */ 1156 if (anon == NULL || pg == NULL) { 1157 if (anon) { 1158 anon->an_ref--; 1159 simple_unlock(&anon->an_lock); 1160 uvm_anfree(anon); 1161 } 1162 uvmfault_unlockall(&ufi, amap, uobj, oanon); 1163 if (anon == NULL || uvm_swapisfull()) { 1164 UVMHIST_LOG(maphist, 1165 "<- failed. out of VM",0,0,0,0); 1166 uvmexp.fltnoanon++; 1167 return ENOMEM; 1168 } 1169 1170 uvmexp.fltnoram++; 1171 uvm_wait("flt_noram3"); /* out of RAM, wait for more */ 1172 goto ReFault; 1173 } 1174 1175 /* got all resources, replace anon with nanon */ 1176 uvm_pagecopy(oanon->u.an_page, pg); 1177 uvm_lock_pageq(); 1178 uvm_pageactivate(pg); 1179 pg->flags &= ~(PG_BUSY|PG_FAKE); 1180 uvm_unlock_pageq(); 1181 UVM_PAGE_OWN(pg, NULL); 1182 amap_add(&ufi.entry->aref, ufi.orig_rvaddr - ufi.entry->start, 1183 anon, 1); 1184 1185 /* deref: can not drop to zero here by defn! */ 1186 oanon->an_ref--; 1187 1188 /* 1189 * note: oanon is still locked, as is the new anon. we 1190 * need to check for this later when we unlock oanon; if 1191 * oanon != anon, we'll have to unlock anon, too. 1192 */ 1193 1194 } else { 1195 1196 uvmexp.flt_anon++; 1197 oanon = anon; /* old, locked anon is same as anon */ 1198 pg = anon->u.an_page; 1199 if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */ 1200 enter_prot = enter_prot & ~VM_PROT_WRITE; 1201 1202 } 1203 1204 /* locked: maps(read), amap, oanon, anon (if different from oanon) */ 1205 1206 /* 1207 * now map the page in. 1208 */ 1209 1210 UVMHIST_LOG(maphist, " MAPPING: anon: pm=0x%x, va=0x%x, pg=0x%x", 1211 ufi.orig_map->pmap, ufi.orig_rvaddr, pg, 0); 1212 if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg), 1213 enter_prot, access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0)) 1214 != 0) { 1215 1216 /* 1217 * No need to undo what we did; we can simply think of 1218 * this as the pmap throwing away the mapping information. 1219 * 1220 * We do, however, have to go through the ReFault path, 1221 * as the map may change while we're asleep. 1222 */ 1223 1224 if (anon != oanon) 1225 simple_unlock(&anon->an_lock); 1226 uvmfault_unlockall(&ufi, amap, uobj, oanon); 1227 if (uvm_swapisfull()) { 1228 UVMHIST_LOG(maphist, 1229 "<- failed. out of VM",0,0,0,0); 1230 /* XXX instrumentation */ 1231 return ENOMEM; 1232 } 1233 /* XXX instrumentation */ 1234 uvm_wait("flt_pmfail1"); 1235 goto ReFault; 1236 } 1237 1238 /* 1239 * ... update the page queues. 1240 */ 1241 1242 uvm_lock_pageq(); 1243 if (wire_fault) { 1244 uvm_pagewire(pg); 1245 1246 /* 1247 * since the now-wired page cannot be paged out, 1248 * release its swap resources for others to use. 1249 * since an anon with no swap cannot be PG_CLEAN, 1250 * clear its clean flag now. 1251 */ 1252 1253 pg->flags &= ~(PG_CLEAN); 1254 uvm_anon_dropswap(anon); 1255 } else { 1256 uvm_pageactivate(pg); 1257 } 1258 uvm_unlock_pageq(); 1259 1260 /* 1261 * done case 1! finish up by unlocking everything and returning success 1262 */ 1263 1264 if (anon != oanon) 1265 simple_unlock(&anon->an_lock); 1266 uvmfault_unlockall(&ufi, amap, uobj, oanon); 1267 pmap_update(ufi.orig_map->pmap); 1268 return 0; 1269 1270 Case2: 1271 /* 1272 * handle case 2: faulting on backing object or zero fill 1273 */ 1274 1275 /* 1276 * locked: 1277 * maps(read), amap(if there), uobj(if !null), uobjpage(if !null) 1278 */ 1279 1280 /* 1281 * note that uobjpage can not be PGO_DONTCARE at this point. we now 1282 * set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we 1283 * have a backing object, check and see if we are going to promote 1284 * the data up to an anon during the fault. 1285 */ 1286 1287 if (uobj == NULL) { 1288 uobjpage = PGO_DONTCARE; 1289 promote = TRUE; /* always need anon here */ 1290 } else { 1291 KASSERT(uobjpage != PGO_DONTCARE); 1292 promote = cow_now && UVM_ET_ISCOPYONWRITE(ufi.entry); 1293 } 1294 UVMHIST_LOG(maphist, " case 2 fault: promote=%d, zfill=%d", 1295 promote, (uobj == NULL), 0,0); 1296 1297 /* 1298 * if uobjpage is not null then we do not need to do I/O to get the 1299 * uobjpage. 1300 * 1301 * if uobjpage is null, then we need to unlock and ask the pager to 1302 * get the data for us. once we have the data, we need to reverify 1303 * the state the world. we are currently not holding any resources. 1304 */ 1305 1306 if (uobjpage) { 1307 /* update rusage counters */ 1308 curproc->p_stats->p_ru.ru_minflt++; 1309 } else { 1310 /* update rusage counters */ 1311 curproc->p_stats->p_ru.ru_majflt++; 1312 1313 /* locked: maps(read), amap(if there), uobj */ 1314 uvmfault_unlockall(&ufi, amap, NULL, NULL); 1315 /* locked: uobj */ 1316 1317 uvmexp.fltget++; 1318 gotpages = 1; 1319 uoff = (ufi.orig_rvaddr - ufi.entry->start) + ufi.entry->offset; 1320 error = uobj->pgops->pgo_get(uobj, uoff, &uobjpage, &gotpages, 1321 0, access_type & MASK(ufi.entry), ufi.entry->advice, 1322 PGO_SYNCIO); 1323 /* locked: uobjpage(if no error) */ 1324 1325 /* 1326 * recover from I/O 1327 */ 1328 1329 if (error) { 1330 if (error == EAGAIN) { 1331 UVMHIST_LOG(maphist, 1332 " pgo_get says TRY AGAIN!",0,0,0,0); 1333 tsleep(&lbolt, PVM, "fltagain2", 0); 1334 goto ReFault; 1335 } 1336 1337 UVMHIST_LOG(maphist, "<- pgo_get failed (code %d)", 1338 error, 0,0,0); 1339 return error; 1340 } 1341 1342 /* locked: uobjpage */ 1343 1344 uvm_lock_pageq(); 1345 uvm_pageactivate(uobjpage); 1346 uvm_unlock_pageq(); 1347 1348 /* 1349 * re-verify the state of the world by first trying to relock 1350 * the maps. always relock the object. 1351 */ 1352 1353 locked = uvmfault_relock(&ufi); 1354 if (locked && amap) 1355 amap_lock(amap); 1356 simple_lock(&uobj->vmobjlock); 1357 1358 /* locked(locked): maps(read), amap(if !null), uobj, uobjpage */ 1359 /* locked(!locked): uobj, uobjpage */ 1360 1361 /* 1362 * verify that the page has not be released and re-verify 1363 * that amap slot is still free. if there is a problem, 1364 * we unlock and clean up. 1365 */ 1366 1367 if ((uobjpage->flags & PG_RELEASED) != 0 || 1368 (locked && amap && 1369 amap_lookup(&ufi.entry->aref, 1370 ufi.orig_rvaddr - ufi.entry->start))) { 1371 if (locked) 1372 uvmfault_unlockall(&ufi, amap, NULL, NULL); 1373 locked = FALSE; 1374 } 1375 1376 /* 1377 * didn't get the lock? release the page and retry. 1378 */ 1379 1380 if (locked == FALSE) { 1381 UVMHIST_LOG(maphist, 1382 " wasn't able to relock after fault: retry", 1383 0,0,0,0); 1384 if (uobjpage->flags & PG_WANTED) 1385 wakeup(uobjpage); 1386 if (uobjpage->flags & PG_RELEASED) { 1387 uvmexp.fltpgrele++; 1388 uvm_pagefree(uobjpage); 1389 goto ReFault; 1390 } 1391 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1392 UVM_PAGE_OWN(uobjpage, NULL); 1393 simple_unlock(&uobj->vmobjlock); 1394 goto ReFault; 1395 } 1396 1397 /* 1398 * we have the data in uobjpage which is busy and 1399 * not released. we are holding object lock (so the page 1400 * can't be released on us). 1401 */ 1402 1403 /* locked: maps(read), amap(if !null), uobj, uobjpage */ 1404 } 1405 1406 /* 1407 * locked: 1408 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj) 1409 */ 1410 1411 /* 1412 * notes: 1413 * - at this point uobjpage can not be NULL 1414 * - at this point uobjpage can not be PG_RELEASED (since we checked 1415 * for it above) 1416 * - at this point uobjpage could be PG_WANTED (handle later) 1417 */ 1418 1419 if (promote == FALSE) { 1420 1421 /* 1422 * we are not promoting. if the mapping is COW ensure that we 1423 * don't give more access than we should (e.g. when doing a read 1424 * fault on a COPYONWRITE mapping we want to map the COW page in 1425 * R/O even though the entry protection could be R/W). 1426 * 1427 * set "pg" to the page we want to map in (uobjpage, usually) 1428 */ 1429 1430 /* no anon in this case. */ 1431 anon = NULL; 1432 1433 uvmexp.flt_obj++; 1434 if (UVM_ET_ISCOPYONWRITE(ufi.entry)) 1435 enter_prot &= ~VM_PROT_WRITE; 1436 pg = uobjpage; /* map in the actual object */ 1437 1438 /* assert(uobjpage != PGO_DONTCARE) */ 1439 1440 /* 1441 * we are faulting directly on the page. be careful 1442 * about writing to loaned pages... 1443 */ 1444 1445 if (uobjpage->loan_count) { 1446 if (!cow_now) { 1447 /* read fault: cap the protection at readonly */ 1448 /* cap! */ 1449 enter_prot = enter_prot & ~VM_PROT_WRITE; 1450 } else { 1451 /* write fault: must break the loan here */ 1452 1453 pg = uvm_loanbreak(uobjpage); 1454 if (pg == NULL) { 1455 1456 /* 1457 * drop ownership of page, it can't 1458 * be released 1459 */ 1460 1461 if (uobjpage->flags & PG_WANTED) 1462 wakeup(uobjpage); 1463 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1464 UVM_PAGE_OWN(uobjpage, NULL); 1465 1466 uvmfault_unlockall(&ufi, amap, uobj, 1467 NULL); 1468 UVMHIST_LOG(maphist, 1469 " out of RAM breaking loan, waiting", 1470 0,0,0,0); 1471 uvmexp.fltnoram++; 1472 uvm_wait("flt_noram4"); 1473 goto ReFault; 1474 } 1475 uobjpage = pg; 1476 } 1477 } 1478 } else { 1479 1480 /* 1481 * if we are going to promote the data to an anon we 1482 * allocate a blank anon here and plug it into our amap. 1483 */ 1484 #if DIAGNOSTIC 1485 if (amap == NULL) 1486 panic("uvm_fault: want to promote data, but no anon"); 1487 #endif 1488 1489 anon = uvm_analloc(); 1490 if (anon) { 1491 1492 /* 1493 * The new anon is locked. 1494 * 1495 * In `Fill in data...' below, if 1496 * uobjpage == PGO_DONTCARE, we want 1497 * a zero'd, dirty page, so have 1498 * uvm_pagealloc() do that for us. 1499 */ 1500 1501 pg = uvm_pagealloc(NULL, 0, anon, 1502 (uobjpage == PGO_DONTCARE) ? UVM_PGA_ZERO : 0); 1503 } 1504 1505 /* 1506 * out of memory resources? 1507 */ 1508 1509 if (anon == NULL || pg == NULL) { 1510 if (anon != NULL) { 1511 anon->an_ref--; 1512 simple_unlock(&anon->an_lock); 1513 uvm_anfree(anon); 1514 } 1515 1516 /* 1517 * arg! must unbusy our page and fail or sleep. 1518 */ 1519 1520 if (uobjpage != PGO_DONTCARE) { 1521 if (uobjpage->flags & PG_WANTED) 1522 /* still holding object lock */ 1523 wakeup(uobjpage); 1524 1525 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1526 UVM_PAGE_OWN(uobjpage, NULL); 1527 } 1528 1529 /* unlock and fail ... */ 1530 uvmfault_unlockall(&ufi, amap, uobj, NULL); 1531 if (anon == NULL || uvm_swapisfull()) { 1532 UVMHIST_LOG(maphist, " promote: out of VM", 1533 0,0,0,0); 1534 uvmexp.fltnoanon++; 1535 return ENOMEM; 1536 } 1537 1538 UVMHIST_LOG(maphist, " out of RAM, waiting for more", 1539 0,0,0,0); 1540 uvmexp.fltnoram++; 1541 uvm_wait("flt_noram5"); 1542 goto ReFault; 1543 } 1544 1545 /* 1546 * fill in the data 1547 */ 1548 1549 if (uobjpage != PGO_DONTCARE) { 1550 uvmexp.flt_prcopy++; 1551 /* copy page [pg now dirty] */ 1552 uvm_pagecopy(uobjpage, pg); 1553 1554 /* 1555 * promote to shared amap? make sure all sharing 1556 * procs see it 1557 */ 1558 1559 if ((amap_flags(amap) & AMAP_SHARED) != 0) { 1560 pmap_page_protect(uobjpage, VM_PROT_NONE); 1561 /* 1562 * XXX: PAGE MIGHT BE WIRED! 1563 */ 1564 } 1565 1566 /* 1567 * dispose of uobjpage. it can't be PG_RELEASED 1568 * since we still hold the object lock. 1569 * drop handle to uobj as well. 1570 */ 1571 1572 if (uobjpage->flags & PG_WANTED) 1573 /* still have the obj lock */ 1574 wakeup(uobjpage); 1575 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1576 UVM_PAGE_OWN(uobjpage, NULL); 1577 simple_unlock(&uobj->vmobjlock); 1578 uobj = NULL; 1579 1580 UVMHIST_LOG(maphist, 1581 " promote uobjpage 0x%x to anon/page 0x%x/0x%x", 1582 uobjpage, anon, pg, 0); 1583 1584 } else { 1585 uvmexp.flt_przero++; 1586 1587 /* 1588 * Page is zero'd and marked dirty by uvm_pagealloc() 1589 * above. 1590 */ 1591 1592 UVMHIST_LOG(maphist," zero fill anon/page 0x%x/0%x", 1593 anon, pg, 0, 0); 1594 } 1595 amap_add(&ufi.entry->aref, ufi.orig_rvaddr - ufi.entry->start, 1596 anon, 0); 1597 } 1598 1599 /* 1600 * locked: 1601 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj), 1602 * anon(if !null), pg(if anon) 1603 * 1604 * note: pg is either the uobjpage or the new page in the new anon 1605 */ 1606 1607 /* 1608 * all resources are present. we can now map it in and free our 1609 * resources. 1610 */ 1611 1612 UVMHIST_LOG(maphist, 1613 " MAPPING: case2: pm=0x%x, va=0x%x, pg=0x%x, promote=%d", 1614 ufi.orig_map->pmap, ufi.orig_rvaddr, pg, promote); 1615 KASSERT((access_type & VM_PROT_WRITE) == 0 || 1616 (pg->flags & PG_RDONLY) == 0); 1617 if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg), 1618 pg->flags & PG_RDONLY ? enter_prot & ~VM_PROT_WRITE : enter_prot, 1619 access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0)) != 0) { 1620 1621 /* 1622 * No need to undo what we did; we can simply think of 1623 * this as the pmap throwing away the mapping information. 1624 * 1625 * We do, however, have to go through the ReFault path, 1626 * as the map may change while we're asleep. 1627 */ 1628 1629 if (pg->flags & PG_WANTED) 1630 wakeup(pg); 1631 1632 /* 1633 * note that pg can't be PG_RELEASED since we did not drop 1634 * the object lock since the last time we checked. 1635 */ 1636 1637 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 1638 UVM_PAGE_OWN(pg, NULL); 1639 uvmfault_unlockall(&ufi, amap, uobj, anon); 1640 if (uvm_swapisfull()) { 1641 UVMHIST_LOG(maphist, 1642 "<- failed. out of VM",0,0,0,0); 1643 /* XXX instrumentation */ 1644 return ENOMEM; 1645 } 1646 /* XXX instrumentation */ 1647 uvm_wait("flt_pmfail2"); 1648 goto ReFault; 1649 } 1650 1651 uvm_lock_pageq(); 1652 if (wire_fault) { 1653 uvm_pagewire(pg); 1654 if (pg->pqflags & PQ_AOBJ) { 1655 1656 /* 1657 * since the now-wired page cannot be paged out, 1658 * release its swap resources for others to use. 1659 * since an aobj page with no swap cannot be PG_CLEAN, 1660 * clear its clean flag now. 1661 */ 1662 1663 pg->flags &= ~(PG_CLEAN); 1664 uao_dropswap(uobj, pg->offset >> PAGE_SHIFT); 1665 } 1666 } else { 1667 uvm_pageactivate(pg); 1668 } 1669 uvm_unlock_pageq(); 1670 if (pg->flags & PG_WANTED) 1671 wakeup(pg); 1672 1673 /* 1674 * note that pg can't be PG_RELEASED since we did not drop the object 1675 * lock since the last time we checked. 1676 */ 1677 1678 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 1679 UVM_PAGE_OWN(pg, NULL); 1680 uvmfault_unlockall(&ufi, amap, uobj, anon); 1681 pmap_update(ufi.orig_map->pmap); 1682 UVMHIST_LOG(maphist, "<- done (SUCCESS!)",0,0,0,0); 1683 return 0; 1684 } 1685 1686 /* 1687 * uvm_fault_wire: wire down a range of virtual addresses in a map. 1688 * 1689 * => map may be read-locked by caller, but MUST NOT be write-locked. 1690 * => if map is read-locked, any operations which may cause map to 1691 * be write-locked in uvm_fault() must be taken care of by 1692 * the caller. See uvm_map_pageable(). 1693 */ 1694 1695 int 1696 uvm_fault_wire(map, start, end, fault_type, access_type) 1697 struct vm_map *map; 1698 vaddr_t start, end; 1699 vm_fault_t fault_type; 1700 vm_prot_t access_type; 1701 { 1702 vaddr_t va; 1703 int error; 1704 1705 /* 1706 * now fault it in a page at a time. if the fault fails then we have 1707 * to undo what we have done. note that in uvm_fault VM_PROT_NONE 1708 * is replaced with the max protection if fault_type is VM_FAULT_WIRE. 1709 */ 1710 1711 /* 1712 * XXX work around overflowing a vaddr_t. this prevents us from 1713 * wiring the last page in the address space, though. 1714 */ 1715 if (start > end) { 1716 return EFAULT; 1717 } 1718 1719 for (va = start ; va < end ; va += PAGE_SIZE) { 1720 error = uvm_fault(map, va, fault_type, access_type); 1721 if (error) { 1722 if (va != start) { 1723 uvm_fault_unwire(map, start, va); 1724 } 1725 return error; 1726 } 1727 } 1728 return 0; 1729 } 1730 1731 /* 1732 * uvm_fault_unwire(): unwire range of virtual space. 1733 */ 1734 1735 void 1736 uvm_fault_unwire(map, start, end) 1737 struct vm_map *map; 1738 vaddr_t start, end; 1739 { 1740 vm_map_lock_read(map); 1741 uvm_fault_unwire_locked(map, start, end); 1742 vm_map_unlock_read(map); 1743 } 1744 1745 /* 1746 * uvm_fault_unwire_locked(): the guts of uvm_fault_unwire(). 1747 * 1748 * => map must be at least read-locked. 1749 */ 1750 1751 void 1752 uvm_fault_unwire_locked(map, start, end) 1753 struct vm_map *map; 1754 vaddr_t start, end; 1755 { 1756 struct vm_map_entry *entry; 1757 pmap_t pmap = vm_map_pmap(map); 1758 vaddr_t va; 1759 paddr_t pa; 1760 struct vm_page *pg; 1761 1762 KASSERT((map->flags & VM_MAP_INTRSAFE) == 0); 1763 1764 /* 1765 * we assume that the area we are unwiring has actually been wired 1766 * in the first place. this means that we should be able to extract 1767 * the PAs from the pmap. we also lock out the page daemon so that 1768 * we can call uvm_pageunwire. 1769 */ 1770 1771 uvm_lock_pageq(); 1772 1773 /* 1774 * find the beginning map entry for the region. 1775 */ 1776 1777 KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map)); 1778 if (uvm_map_lookup_entry(map, start, &entry) == FALSE) 1779 panic("uvm_fault_unwire_locked: address not in map"); 1780 1781 for (va = start; va < end; va += PAGE_SIZE) { 1782 if (pmap_extract(pmap, va, &pa) == FALSE) 1783 continue; 1784 1785 /* 1786 * find the map entry for the current address. 1787 */ 1788 1789 KASSERT(va >= entry->start); 1790 while (va >= entry->end) { 1791 KASSERT(entry->next != &map->header && 1792 entry->next->start <= entry->end); 1793 entry = entry->next; 1794 } 1795 1796 /* 1797 * if the entry is no longer wired, tell the pmap. 1798 */ 1799 1800 if (VM_MAPENT_ISWIRED(entry) == 0) 1801 pmap_unwire(pmap, va); 1802 1803 pg = PHYS_TO_VM_PAGE(pa); 1804 if (pg) 1805 uvm_pageunwire(pg); 1806 } 1807 1808 uvm_unlock_pageq(); 1809 } 1810