1 /* $NetBSD: uvm_fault.c,v 1.74 2002/01/02 01:10:36 chs 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 1.74 2002/01/02 01:10:36 chs 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_addr->u_stats.p_ru.ru_minflt++; 308 else 309 curproc->p_addr->u_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 uvm_swap_markbad(anon->an_swslot, 1); 442 anon->an_swslot = SWSLOT_BAD; 443 444 /* 445 * note: page was never !PG_BUSY, so it 446 * can't be mapped and thus no need to 447 * pmap_page_protect it... 448 */ 449 450 uvm_lock_pageq(); 451 uvm_pagefree(pg); 452 uvm_unlock_pageq(); 453 454 if (locked) 455 uvmfault_unlockall(ufi, amap, NULL, 456 anon); 457 else 458 simple_unlock(&anon->an_lock); 459 UVMHIST_LOG(maphist, "<- ERROR", 0,0,0,0); 460 return error; 461 } 462 463 /* 464 * we've successfully read the page, activate it. 465 */ 466 467 uvm_lock_pageq(); 468 uvm_pageactivate(pg); 469 uvm_unlock_pageq(); 470 pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE); 471 UVM_PAGE_OWN(pg, NULL); 472 if (!locked) 473 simple_unlock(&anon->an_lock); 474 } 475 476 /* 477 * we were not able to relock. restart fault. 478 */ 479 480 if (!locked) { 481 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 482 return (ERESTART); 483 } 484 485 /* 486 * verify no one has touched the amap and moved the anon on us. 487 */ 488 489 if (ufi != NULL && 490 amap_lookup(&ufi->entry->aref, 491 ufi->orig_rvaddr - ufi->entry->start) != anon) { 492 493 uvmfault_unlockall(ufi, amap, NULL, anon); 494 UVMHIST_LOG(maphist, "<- REFAULT", 0,0,0,0); 495 return (ERESTART); 496 } 497 498 /* 499 * try it again! 500 */ 501 502 uvmexp.fltanretry++; 503 continue; 504 } 505 /*NOTREACHED*/ 506 } 507 508 /* 509 * F A U L T - m a i n e n t r y p o i n t 510 */ 511 512 /* 513 * uvm_fault: page fault handler 514 * 515 * => called from MD code to resolve a page fault 516 * => VM data structures usually should be unlocked. however, it is 517 * possible to call here with the main map locked if the caller 518 * gets a write lock, sets it recusive, and then calls us (c.f. 519 * uvm_map_pageable). this should be avoided because it keeps 520 * the map locked off during I/O. 521 * => MUST NEVER BE CALLED IN INTERRUPT CONTEXT 522 */ 523 524 #define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \ 525 ~VM_PROT_WRITE : VM_PROT_ALL) 526 527 int 528 uvm_fault(orig_map, vaddr, fault_type, access_type) 529 struct vm_map *orig_map; 530 vaddr_t vaddr; 531 vm_fault_t fault_type; 532 vm_prot_t access_type; 533 { 534 struct uvm_faultinfo ufi; 535 vm_prot_t enter_prot, check_prot; 536 boolean_t wired, narrow, promote, locked, shadowed, wire_fault, cow_now; 537 int npages, nback, nforw, centeridx, error, lcv, gotpages; 538 vaddr_t startva, objaddr, currva, offset, uoff; 539 paddr_t pa; 540 struct vm_amap *amap; 541 struct uvm_object *uobj; 542 struct vm_anon *anons_store[UVM_MAXRANGE], **anons, *anon, *oanon; 543 struct vm_page *pages[UVM_MAXRANGE], *pg, *uobjpage; 544 UVMHIST_FUNC("uvm_fault"); UVMHIST_CALLED(maphist); 545 546 UVMHIST_LOG(maphist, "(map=0x%x, vaddr=0x%x, ft=%d, at=%d)", 547 orig_map, vaddr, fault_type, access_type); 548 549 anon = NULL; 550 pg = NULL; 551 552 uvmexp.faults++; /* XXX: locking? */ 553 554 /* 555 * init the IN parameters in the ufi 556 */ 557 558 ufi.orig_map = orig_map; 559 ufi.orig_rvaddr = trunc_page(vaddr); 560 ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */ 561 wire_fault = fault_type == VM_FAULT_WIRE || 562 fault_type == VM_FAULT_WIREMAX; 563 if (wire_fault) 564 narrow = TRUE; /* don't look for neighborhood 565 * pages on wire */ 566 else 567 narrow = FALSE; /* normal fault */ 568 569 /* 570 * "goto ReFault" means restart the page fault from ground zero. 571 */ 572 ReFault: 573 574 /* 575 * lookup and lock the maps 576 */ 577 578 if (uvmfault_lookup(&ufi, FALSE) == FALSE) { 579 UVMHIST_LOG(maphist, "<- no mapping @ 0x%x", vaddr, 0,0,0); 580 return (EFAULT); 581 } 582 /* locked: maps(read) */ 583 584 #ifdef DIAGNOSTIC 585 if ((ufi.map->flags & VM_MAP_PAGEABLE) == 0) { 586 printf("Page fault on non-pageable map:\n"); 587 printf("ufi.map = %p\n", ufi.map); 588 printf("ufi.orig_map = %p\n", ufi.orig_map); 589 printf("ufi.orig_rvaddr = 0x%lx\n", (u_long) ufi.orig_rvaddr); 590 panic("uvm_fault: (ufi.map->flags & VM_MAP_PAGEABLE) == 0"); 591 } 592 #endif 593 594 /* 595 * check protection 596 */ 597 598 check_prot = fault_type == VM_FAULT_WIREMAX ? 599 ufi.entry->max_protection : ufi.entry->protection; 600 if ((check_prot & access_type) != access_type) { 601 UVMHIST_LOG(maphist, 602 "<- protection failure (prot=0x%x, access=0x%x)", 603 ufi.entry->protection, access_type, 0, 0); 604 uvmfault_unlockmaps(&ufi, FALSE); 605 return EACCES; 606 } 607 608 /* 609 * "enter_prot" is the protection we want to enter the page in at. 610 * for certain pages (e.g. copy-on-write pages) this protection can 611 * be more strict than ufi.entry->protection. "wired" means either 612 * the entry is wired or we are fault-wiring the pg. 613 */ 614 615 enter_prot = ufi.entry->protection; 616 wired = VM_MAPENT_ISWIRED(ufi.entry) || wire_fault; 617 if (wired) { 618 access_type = enter_prot; /* full access for wired */ 619 cow_now = (check_prot & VM_PROT_WRITE) != 0; 620 } else { 621 cow_now = (access_type & VM_PROT_WRITE) != 0; 622 } 623 624 /* 625 * handle "needs_copy" case. if we need to copy the amap we will 626 * have to drop our readlock and relock it with a write lock. (we 627 * need a write lock to change anything in a map entry [e.g. 628 * needs_copy]). 629 */ 630 631 if (UVM_ET_ISNEEDSCOPY(ufi.entry)) { 632 KASSERT(fault_type != VM_FAULT_WIREMAX); 633 if (cow_now || (ufi.entry->object.uvm_obj == NULL)) { 634 /* need to clear */ 635 UVMHIST_LOG(maphist, 636 " need to clear needs_copy and refault",0,0,0,0); 637 uvmfault_unlockmaps(&ufi, FALSE); 638 uvmfault_amapcopy(&ufi); 639 uvmexp.fltamcopy++; 640 goto ReFault; 641 642 } else { 643 644 /* 645 * ensure that we pmap_enter page R/O since 646 * needs_copy is still true 647 */ 648 649 enter_prot &= ~VM_PROT_WRITE; 650 } 651 } 652 653 /* 654 * identify the players 655 */ 656 657 amap = ufi.entry->aref.ar_amap; /* top layer */ 658 uobj = ufi.entry->object.uvm_obj; /* bottom layer */ 659 660 /* 661 * check for a case 0 fault. if nothing backing the entry then 662 * error now. 663 */ 664 665 if (amap == NULL && uobj == NULL) { 666 uvmfault_unlockmaps(&ufi, FALSE); 667 UVMHIST_LOG(maphist,"<- no backing store, no overlay",0,0,0,0); 668 return (EFAULT); 669 } 670 671 /* 672 * establish range of interest based on advice from mapper 673 * and then clip to fit map entry. note that we only want 674 * to do this the first time through the fault. if we 675 * ReFault we will disable this by setting "narrow" to true. 676 */ 677 678 if (narrow == FALSE) { 679 680 /* wide fault (!narrow) */ 681 KASSERT(uvmadvice[ufi.entry->advice].advice == 682 ufi.entry->advice); 683 nback = MIN(uvmadvice[ufi.entry->advice].nback, 684 (ufi.orig_rvaddr - ufi.entry->start) >> PAGE_SHIFT); 685 startva = ufi.orig_rvaddr - (nback << PAGE_SHIFT); 686 nforw = MIN(uvmadvice[ufi.entry->advice].nforw, 687 ((ufi.entry->end - ufi.orig_rvaddr) >> 688 PAGE_SHIFT) - 1); 689 /* 690 * note: "-1" because we don't want to count the 691 * faulting page as forw 692 */ 693 npages = nback + nforw + 1; 694 centeridx = nback; 695 696 narrow = TRUE; /* ensure only once per-fault */ 697 698 } else { 699 700 /* narrow fault! */ 701 nback = nforw = 0; 702 startva = ufi.orig_rvaddr; 703 npages = 1; 704 centeridx = 0; 705 706 } 707 708 /* locked: maps(read) */ 709 UVMHIST_LOG(maphist, " narrow=%d, back=%d, forw=%d, startva=0x%x", 710 narrow, nback, nforw, startva); 711 UVMHIST_LOG(maphist, " entry=0x%x, amap=0x%x, obj=0x%x", ufi.entry, 712 amap, uobj, 0); 713 714 /* 715 * if we've got an amap, lock it and extract current anons. 716 */ 717 718 if (amap) { 719 amap_lock(amap); 720 anons = anons_store; 721 amap_lookups(&ufi.entry->aref, startva - ufi.entry->start, 722 anons, npages); 723 } else { 724 anons = NULL; /* to be safe */ 725 } 726 727 /* locked: maps(read), amap(if there) */ 728 729 /* 730 * for MADV_SEQUENTIAL mappings we want to deactivate the back pages 731 * now and then forget about them (for the rest of the fault). 732 */ 733 734 if (ufi.entry->advice == MADV_SEQUENTIAL && nback != 0) { 735 736 UVMHIST_LOG(maphist, " MADV_SEQUENTIAL: flushing backpages", 737 0,0,0,0); 738 /* flush back-page anons? */ 739 if (amap) 740 uvmfault_anonflush(anons, nback); 741 742 /* flush object? */ 743 if (uobj) { 744 objaddr = 745 (startva - ufi.entry->start) + ufi.entry->offset; 746 simple_lock(&uobj->vmobjlock); 747 (void) (uobj->pgops->pgo_put)(uobj, objaddr, objaddr + 748 (nback << PAGE_SHIFT), PGO_DEACTIVATE); 749 } 750 751 /* now forget about the backpages */ 752 if (amap) 753 anons += nback; 754 startva += (nback << PAGE_SHIFT); 755 npages -= nback; 756 nback = centeridx = 0; 757 } 758 759 /* locked: maps(read), amap(if there) */ 760 761 /* 762 * map in the backpages and frontpages we found in the amap in hopes 763 * of preventing future faults. we also init the pages[] array as 764 * we go. 765 */ 766 767 currva = startva; 768 shadowed = FALSE; 769 for (lcv = 0 ; lcv < npages ; lcv++, currva += PAGE_SIZE) { 770 771 /* 772 * dont play with VAs that are already mapped 773 * except for center) 774 */ 775 if (lcv != centeridx && 776 pmap_extract(ufi.orig_map->pmap, currva, &pa)) { 777 pages[lcv] = PGO_DONTCARE; 778 continue; 779 } 780 781 /* 782 * unmapped or center page. check if any anon at this level. 783 */ 784 if (amap == NULL || anons[lcv] == NULL) { 785 pages[lcv] = NULL; 786 continue; 787 } 788 789 /* 790 * check for present page and map if possible. re-activate it. 791 */ 792 793 pages[lcv] = PGO_DONTCARE; 794 if (lcv == centeridx) { /* save center for later! */ 795 shadowed = TRUE; 796 continue; 797 } 798 anon = anons[lcv]; 799 simple_lock(&anon->an_lock); 800 /* ignore loaned pages */ 801 if (anon->u.an_page && anon->u.an_page->loan_count == 0 && 802 (anon->u.an_page->flags & PG_BUSY) == 0) { 803 uvm_lock_pageq(); 804 uvm_pageactivate(anon->u.an_page); 805 uvm_unlock_pageq(); 806 UVMHIST_LOG(maphist, 807 " MAPPING: n anon: pm=0x%x, va=0x%x, pg=0x%x", 808 ufi.orig_map->pmap, currva, anon->u.an_page, 0); 809 uvmexp.fltnamap++; 810 811 /* 812 * Since this isn't the page that's actually faulting, 813 * ignore pmap_enter() failures; it's not critical 814 * that we enter these right now. 815 */ 816 817 (void) pmap_enter(ufi.orig_map->pmap, currva, 818 VM_PAGE_TO_PHYS(anon->u.an_page), 819 (anon->an_ref > 1) ? (enter_prot & ~VM_PROT_WRITE) : 820 enter_prot, 821 PMAP_CANFAIL | 822 (VM_MAPENT_ISWIRED(ufi.entry) ? PMAP_WIRED : 0)); 823 } 824 simple_unlock(&anon->an_lock); 825 pmap_update(ufi.orig_map->pmap); 826 } 827 828 /* locked: maps(read), amap(if there) */ 829 /* (shadowed == TRUE) if there is an anon at the faulting address */ 830 UVMHIST_LOG(maphist, " shadowed=%d, will_get=%d", shadowed, 831 (uobj && shadowed == FALSE),0,0); 832 833 /* 834 * note that if we are really short of RAM we could sleep in the above 835 * call to pmap_enter with everything locked. bad? 836 * 837 * XXX Actually, that is bad; pmap_enter() should just fail in that 838 * XXX case. --thorpej 839 */ 840 841 /* 842 * if the desired page is not shadowed by the amap and we have a 843 * backing object, then we check to see if the backing object would 844 * prefer to handle the fault itself (rather than letting us do it 845 * with the usual pgo_get hook). the backing object signals this by 846 * providing a pgo_fault routine. 847 */ 848 849 if (uobj && shadowed == FALSE && uobj->pgops->pgo_fault != NULL) { 850 simple_lock(&uobj->vmobjlock); 851 852 /* locked: maps(read), amap (if there), uobj */ 853 error = uobj->pgops->pgo_fault(&ufi, startva, pages, npages, 854 centeridx, fault_type, access_type, PGO_LOCKED|PGO_SYNCIO); 855 856 /* locked: nothing, pgo_fault has unlocked everything */ 857 858 if (error == ERESTART) 859 goto ReFault; /* try again! */ 860 /* 861 * object fault routine responsible for pmap_update(). 862 */ 863 return error; 864 } 865 866 /* 867 * now, if the desired page is not shadowed by the amap and we have 868 * a backing object that does not have a special fault routine, then 869 * we ask (with pgo_get) the object for resident pages that we care 870 * about and attempt to map them in. we do not let pgo_get block 871 * (PGO_LOCKED). 872 */ 873 874 if (uobj && shadowed == FALSE) { 875 simple_lock(&uobj->vmobjlock); 876 877 /* locked (!shadowed): maps(read), amap (if there), uobj */ 878 /* 879 * the following call to pgo_get does _not_ change locking state 880 */ 881 882 uvmexp.fltlget++; 883 gotpages = npages; 884 (void) uobj->pgops->pgo_get(uobj, ufi.entry->offset + 885 (startva - ufi.entry->start), 886 pages, &gotpages, centeridx, 887 access_type & MASK(ufi.entry), 888 ufi.entry->advice, PGO_LOCKED); 889 890 /* 891 * check for pages to map, if we got any 892 */ 893 894 uobjpage = NULL; 895 896 if (gotpages) { 897 currva = startva; 898 for (lcv = 0; lcv < npages; 899 lcv++, currva += PAGE_SIZE) { 900 if (pages[lcv] == NULL || 901 pages[lcv] == PGO_DONTCARE) { 902 continue; 903 } 904 905 /* 906 * if center page is resident and not 907 * PG_BUSY|PG_RELEASED then pgo_get 908 * made it PG_BUSY for us and gave 909 * us a handle to it. remember this 910 * page as "uobjpage." (for later use). 911 */ 912 913 if (lcv == centeridx) { 914 uobjpage = pages[lcv]; 915 UVMHIST_LOG(maphist, " got uobjpage " 916 "(0x%x) with locked get", 917 uobjpage, 0,0,0); 918 continue; 919 } 920 921 /* 922 * calling pgo_get with PGO_LOCKED returns us 923 * pages which are neither busy nor released, 924 * so we don't need to check for this. 925 * we can just directly enter the pages. 926 */ 927 928 uvm_lock_pageq(); 929 uvm_pageactivate(pages[lcv]); 930 uvm_unlock_pageq(); 931 UVMHIST_LOG(maphist, 932 " MAPPING: n obj: pm=0x%x, va=0x%x, pg=0x%x", 933 ufi.orig_map->pmap, currva, pages[lcv], 0); 934 uvmexp.fltnomap++; 935 936 /* 937 * Since this page isn't the page that's 938 * actually fauling, ignore pmap_enter() 939 * failures; it's not critical that we 940 * enter these right now. 941 */ 942 943 (void) pmap_enter(ufi.orig_map->pmap, currva, 944 VM_PAGE_TO_PHYS(pages[lcv]), 945 pages[lcv]->flags & PG_RDONLY ? 946 VM_PROT_READ : enter_prot & MASK(ufi.entry), 947 PMAP_CANFAIL | 948 (wired ? PMAP_WIRED : 0)); 949 950 /* 951 * NOTE: page can't be PG_WANTED or PG_RELEASED 952 * because we've held the lock the whole time 953 * we've had the handle. 954 */ 955 956 pages[lcv]->flags &= ~(PG_BUSY); 957 UVM_PAGE_OWN(pages[lcv], NULL); 958 } 959 pmap_update(ufi.orig_map->pmap); 960 } 961 } else { 962 uobjpage = NULL; 963 } 964 965 /* locked (shadowed): maps(read), amap */ 966 /* locked (!shadowed): maps(read), amap(if there), 967 uobj(if !null), uobjpage(if !null) */ 968 969 /* 970 * note that at this point we are done with any front or back pages. 971 * we are now going to focus on the center page (i.e. the one we've 972 * faulted on). if we have faulted on the top (anon) layer 973 * [i.e. case 1], then the anon we want is anons[centeridx] (we have 974 * not touched it yet). if we have faulted on the bottom (uobj) 975 * layer [i.e. case 2] and the page was both present and available, 976 * then we've got a pointer to it as "uobjpage" and we've already 977 * made it BUSY. 978 */ 979 980 /* 981 * there are four possible cases we must address: 1A, 1B, 2A, and 2B 982 */ 983 984 /* 985 * redirect case 2: if we are not shadowed, go to case 2. 986 */ 987 988 if (shadowed == FALSE) 989 goto Case2; 990 991 /* locked: maps(read), amap */ 992 993 /* 994 * handle case 1: fault on an anon in our amap 995 */ 996 997 anon = anons[centeridx]; 998 UVMHIST_LOG(maphist, " case 1 fault: anon=0x%x", anon, 0,0,0); 999 simple_lock(&anon->an_lock); 1000 1001 /* locked: maps(read), amap, anon */ 1002 1003 /* 1004 * no matter if we have case 1A or case 1B we are going to need to 1005 * have the anon's memory resident. ensure that now. 1006 */ 1007 1008 /* 1009 * let uvmfault_anonget do the dirty work. 1010 * if it fails (!OK) it will unlock everything for us. 1011 * if it succeeds, locks are still valid and locked. 1012 * also, if it is OK, then the anon's page is on the queues. 1013 * if the page is on loan from a uvm_object, then anonget will 1014 * lock that object for us if it does not fail. 1015 */ 1016 1017 error = uvmfault_anonget(&ufi, amap, anon); 1018 switch (error) { 1019 case 0: 1020 break; 1021 1022 case ERESTART: 1023 goto ReFault; 1024 1025 case EAGAIN: 1026 tsleep(&lbolt, PVM, "fltagain1", 0); 1027 goto ReFault; 1028 1029 default: 1030 return error; 1031 } 1032 1033 /* 1034 * uobj is non null if the page is on loan from an object (i.e. uobj) 1035 */ 1036 1037 uobj = anon->u.an_page->uobject; /* locked by anonget if !NULL */ 1038 1039 /* locked: maps(read), amap, anon, uobj(if one) */ 1040 1041 /* 1042 * special handling for loaned pages 1043 */ 1044 1045 if (anon->u.an_page->loan_count) { 1046 1047 if (!cow_now) { 1048 1049 /* 1050 * for read faults on loaned pages we just cap the 1051 * protection at read-only. 1052 */ 1053 1054 enter_prot = enter_prot & ~VM_PROT_WRITE; 1055 1056 } else { 1057 /* 1058 * note that we can't allow writes into a loaned page! 1059 * 1060 * if we have a write fault on a loaned page in an 1061 * anon then we need to look at the anon's ref count. 1062 * if it is greater than one then we are going to do 1063 * a normal copy-on-write fault into a new anon (this 1064 * is not a problem). however, if the reference count 1065 * is one (a case where we would normally allow a 1066 * write directly to the page) then we need to kill 1067 * the loan before we continue. 1068 */ 1069 1070 /* >1 case is already ok */ 1071 if (anon->an_ref == 1) { 1072 1073 /* get new un-owned replacement page */ 1074 pg = uvm_pagealloc(NULL, 0, NULL, 0); 1075 if (pg == NULL) { 1076 uvmfault_unlockall(&ufi, amap, uobj, 1077 anon); 1078 uvm_wait("flt_noram2"); 1079 goto ReFault; 1080 } 1081 1082 /* 1083 * copy data, kill loan, and drop uobj lock 1084 * (if any) 1085 */ 1086 /* copy old -> new */ 1087 uvm_pagecopy(anon->u.an_page, pg); 1088 1089 /* force reload */ 1090 pmap_page_protect(anon->u.an_page, 1091 VM_PROT_NONE); 1092 uvm_lock_pageq(); /* KILL loan */ 1093 if (uobj) 1094 /* if we were loaning */ 1095 anon->u.an_page->loan_count--; 1096 anon->u.an_page->uanon = NULL; 1097 /* in case we owned */ 1098 anon->u.an_page->pqflags &= ~PQ_ANON; 1099 uvm_unlock_pageq(); 1100 if (uobj) { 1101 simple_unlock(&uobj->vmobjlock); 1102 uobj = NULL; 1103 } 1104 1105 /* install new page in anon */ 1106 anon->u.an_page = pg; 1107 pg->uanon = anon; 1108 pg->pqflags |= PQ_ANON; 1109 pg->flags &= ~(PG_BUSY|PG_FAKE); 1110 UVM_PAGE_OWN(pg, NULL); 1111 1112 /* done! */ 1113 } /* ref == 1 */ 1114 } /* write fault */ 1115 } /* loan count */ 1116 1117 /* 1118 * if we are case 1B then we will need to allocate a new blank 1119 * anon to transfer the data into. note that we have a lock 1120 * on anon, so no one can busy or release the page until we are done. 1121 * also note that the ref count can't drop to zero here because 1122 * it is > 1 and we are only dropping one ref. 1123 * 1124 * in the (hopefully very rare) case that we are out of RAM we 1125 * will unlock, wait for more RAM, and refault. 1126 * 1127 * if we are out of anon VM we kill the process (XXX: could wait?). 1128 */ 1129 1130 if (cow_now && anon->an_ref > 1) { 1131 1132 UVMHIST_LOG(maphist, " case 1B: COW fault",0,0,0,0); 1133 uvmexp.flt_acow++; 1134 oanon = anon; /* oanon = old, locked anon */ 1135 anon = uvm_analloc(); 1136 if (anon) { 1137 /* new anon is locked! */ 1138 pg = uvm_pagealloc(NULL, 0, anon, 0); 1139 } 1140 1141 /* check for out of RAM */ 1142 if (anon == NULL || pg == NULL) { 1143 if (anon) { 1144 anon->an_ref--; 1145 simple_unlock(&anon->an_lock); 1146 uvm_anfree(anon); 1147 } 1148 uvmfault_unlockall(&ufi, amap, uobj, oanon); 1149 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 1150 if (anon == NULL || uvmexp.swpgonly == uvmexp.swpages) { 1151 UVMHIST_LOG(maphist, 1152 "<- failed. out of VM",0,0,0,0); 1153 uvmexp.fltnoanon++; 1154 return ENOMEM; 1155 } 1156 1157 uvmexp.fltnoram++; 1158 uvm_wait("flt_noram3"); /* out of RAM, wait for more */ 1159 goto ReFault; 1160 } 1161 1162 /* got all resources, replace anon with nanon */ 1163 uvm_pagecopy(oanon->u.an_page, pg); 1164 uvm_pageactivate(pg); 1165 pg->flags &= ~(PG_BUSY|PG_FAKE); 1166 UVM_PAGE_OWN(pg, NULL); 1167 amap_add(&ufi.entry->aref, ufi.orig_rvaddr - ufi.entry->start, 1168 anon, 1); 1169 1170 /* deref: can not drop to zero here by defn! */ 1171 oanon->an_ref--; 1172 1173 /* 1174 * note: oanon is still locked, as is the new anon. we 1175 * need to check for this later when we unlock oanon; if 1176 * oanon != anon, we'll have to unlock anon, too. 1177 */ 1178 1179 } else { 1180 1181 uvmexp.flt_anon++; 1182 oanon = anon; /* old, locked anon is same as anon */ 1183 pg = anon->u.an_page; 1184 if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */ 1185 enter_prot = enter_prot & ~VM_PROT_WRITE; 1186 1187 } 1188 1189 /* locked: maps(read), amap, oanon, anon (if different from oanon) */ 1190 1191 /* 1192 * now map the page in. 1193 */ 1194 1195 UVMHIST_LOG(maphist, " MAPPING: anon: pm=0x%x, va=0x%x, pg=0x%x", 1196 ufi.orig_map->pmap, ufi.orig_rvaddr, pg, 0); 1197 if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg), 1198 enter_prot, access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0)) 1199 != 0) { 1200 1201 /* 1202 * No need to undo what we did; we can simply think of 1203 * this as the pmap throwing away the mapping information. 1204 * 1205 * We do, however, have to go through the ReFault path, 1206 * as the map may change while we're asleep. 1207 */ 1208 1209 if (anon != oanon) 1210 simple_unlock(&anon->an_lock); 1211 uvmfault_unlockall(&ufi, amap, uobj, oanon); 1212 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 1213 if (uvmexp.swpgonly == uvmexp.swpages) { 1214 UVMHIST_LOG(maphist, 1215 "<- failed. out of VM",0,0,0,0); 1216 /* XXX instrumentation */ 1217 return ENOMEM; 1218 } 1219 /* XXX instrumentation */ 1220 uvm_wait("flt_pmfail1"); 1221 goto ReFault; 1222 } 1223 1224 /* 1225 * ... update the page queues. 1226 */ 1227 1228 uvm_lock_pageq(); 1229 if (wire_fault) { 1230 uvm_pagewire(pg); 1231 1232 /* 1233 * since the now-wired page cannot be paged out, 1234 * release its swap resources for others to use. 1235 * since an anon with no swap cannot be PG_CLEAN, 1236 * clear its clean flag now. 1237 */ 1238 1239 pg->flags &= ~(PG_CLEAN); 1240 uvm_anon_dropswap(anon); 1241 } else { 1242 uvm_pageactivate(pg); 1243 } 1244 uvm_unlock_pageq(); 1245 1246 /* 1247 * done case 1! finish up by unlocking everything and returning success 1248 */ 1249 1250 if (anon != oanon) 1251 simple_unlock(&anon->an_lock); 1252 uvmfault_unlockall(&ufi, amap, uobj, oanon); 1253 pmap_update(ufi.orig_map->pmap); 1254 return 0; 1255 1256 Case2: 1257 /* 1258 * handle case 2: faulting on backing object or zero fill 1259 */ 1260 1261 /* 1262 * locked: 1263 * maps(read), amap(if there), uobj(if !null), uobjpage(if !null) 1264 */ 1265 1266 /* 1267 * note that uobjpage can not be PGO_DONTCARE at this point. we now 1268 * set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we 1269 * have a backing object, check and see if we are going to promote 1270 * the data up to an anon during the fault. 1271 */ 1272 1273 if (uobj == NULL) { 1274 uobjpage = PGO_DONTCARE; 1275 promote = TRUE; /* always need anon here */ 1276 } else { 1277 KASSERT(uobjpage != PGO_DONTCARE); 1278 promote = cow_now && UVM_ET_ISCOPYONWRITE(ufi.entry); 1279 } 1280 UVMHIST_LOG(maphist, " case 2 fault: promote=%d, zfill=%d", 1281 promote, (uobj == NULL), 0,0); 1282 1283 /* 1284 * if uobjpage is not null then we do not need to do I/O to get the 1285 * uobjpage. 1286 * 1287 * if uobjpage is null, then we need to unlock and ask the pager to 1288 * get the data for us. once we have the data, we need to reverify 1289 * the state the world. we are currently not holding any resources. 1290 */ 1291 1292 if (uobjpage) { 1293 /* update rusage counters */ 1294 curproc->p_addr->u_stats.p_ru.ru_minflt++; 1295 } else { 1296 /* update rusage counters */ 1297 curproc->p_addr->u_stats.p_ru.ru_majflt++; 1298 1299 /* locked: maps(read), amap(if there), uobj */ 1300 uvmfault_unlockall(&ufi, amap, NULL, NULL); 1301 /* locked: uobj */ 1302 1303 uvmexp.fltget++; 1304 gotpages = 1; 1305 uoff = (ufi.orig_rvaddr - ufi.entry->start) + ufi.entry->offset; 1306 error = uobj->pgops->pgo_get(uobj, uoff, &uobjpage, &gotpages, 1307 0, access_type & MASK(ufi.entry), ufi.entry->advice, 1308 PGO_SYNCIO); 1309 /* locked: uobjpage(if no error) */ 1310 1311 /* 1312 * recover from I/O 1313 */ 1314 1315 if (error) { 1316 if (error == EAGAIN) { 1317 UVMHIST_LOG(maphist, 1318 " pgo_get says TRY AGAIN!",0,0,0,0); 1319 tsleep(&lbolt, PVM, "fltagain2", 0); 1320 goto ReFault; 1321 } 1322 1323 UVMHIST_LOG(maphist, "<- pgo_get failed (code %d)", 1324 error, 0,0,0); 1325 return error; 1326 } 1327 1328 /* locked: uobjpage */ 1329 1330 uvm_lock_pageq(); 1331 uvm_pageactivate(uobjpage); 1332 uvm_unlock_pageq(); 1333 1334 /* 1335 * re-verify the state of the world by first trying to relock 1336 * the maps. always relock the object. 1337 */ 1338 1339 locked = uvmfault_relock(&ufi); 1340 if (locked && amap) 1341 amap_lock(amap); 1342 simple_lock(&uobj->vmobjlock); 1343 1344 /* locked(locked): maps(read), amap(if !null), uobj, uobjpage */ 1345 /* locked(!locked): uobj, uobjpage */ 1346 1347 /* 1348 * verify that the page has not be released and re-verify 1349 * that amap slot is still free. if there is a problem, 1350 * we unlock and clean up. 1351 */ 1352 1353 if ((uobjpage->flags & PG_RELEASED) != 0 || 1354 (locked && amap && 1355 amap_lookup(&ufi.entry->aref, 1356 ufi.orig_rvaddr - ufi.entry->start))) { 1357 if (locked) 1358 uvmfault_unlockall(&ufi, amap, NULL, NULL); 1359 locked = FALSE; 1360 } 1361 1362 /* 1363 * didn't get the lock? release the page and retry. 1364 */ 1365 1366 if (locked == FALSE) { 1367 UVMHIST_LOG(maphist, 1368 " wasn't able to relock after fault: retry", 1369 0,0,0,0); 1370 if (uobjpage->flags & PG_WANTED) 1371 wakeup(uobjpage); 1372 if (uobjpage->flags & PG_RELEASED) { 1373 uvmexp.fltpgrele++; 1374 uvm_pagefree(uobjpage); 1375 goto ReFault; 1376 } 1377 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1378 UVM_PAGE_OWN(uobjpage, NULL); 1379 simple_unlock(&uobj->vmobjlock); 1380 goto ReFault; 1381 } 1382 1383 /* 1384 * we have the data in uobjpage which is busy and 1385 * not released. we are holding object lock (so the page 1386 * can't be released on us). 1387 */ 1388 1389 /* locked: maps(read), amap(if !null), uobj, uobjpage */ 1390 } 1391 1392 /* 1393 * locked: 1394 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj) 1395 */ 1396 1397 /* 1398 * notes: 1399 * - at this point uobjpage can not be NULL 1400 * - at this point uobjpage can not be PG_RELEASED (since we checked 1401 * for it above) 1402 * - at this point uobjpage could be PG_WANTED (handle later) 1403 */ 1404 1405 if (promote == FALSE) { 1406 1407 /* 1408 * we are not promoting. if the mapping is COW ensure that we 1409 * don't give more access than we should (e.g. when doing a read 1410 * fault on a COPYONWRITE mapping we want to map the COW page in 1411 * R/O even though the entry protection could be R/W). 1412 * 1413 * set "pg" to the page we want to map in (uobjpage, usually) 1414 */ 1415 1416 /* no anon in this case. */ 1417 anon = NULL; 1418 1419 uvmexp.flt_obj++; 1420 if (UVM_ET_ISCOPYONWRITE(ufi.entry)) 1421 enter_prot &= ~VM_PROT_WRITE; 1422 pg = uobjpage; /* map in the actual object */ 1423 1424 /* assert(uobjpage != PGO_DONTCARE) */ 1425 1426 /* 1427 * we are faulting directly on the page. be careful 1428 * about writing to loaned pages... 1429 */ 1430 1431 if (uobjpage->loan_count) { 1432 if (!cow_now) { 1433 /* read fault: cap the protection at readonly */ 1434 /* cap! */ 1435 enter_prot = enter_prot & ~VM_PROT_WRITE; 1436 } else { 1437 /* write fault: must break the loan here */ 1438 1439 /* alloc new un-owned page */ 1440 pg = uvm_pagealloc(NULL, 0, NULL, 0); 1441 1442 if (pg == NULL) { 1443 1444 /* 1445 * drop ownership of page, it can't 1446 * be released 1447 */ 1448 1449 if (uobjpage->flags & PG_WANTED) 1450 wakeup(uobjpage); 1451 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1452 UVM_PAGE_OWN(uobjpage, NULL); 1453 1454 uvmfault_unlockall(&ufi, amap, uobj, 1455 NULL); 1456 UVMHIST_LOG(maphist, 1457 " out of RAM breaking loan, waiting", 1458 0,0,0,0); 1459 uvmexp.fltnoram++; 1460 uvm_wait("flt_noram4"); 1461 goto ReFault; 1462 } 1463 1464 /* 1465 * copy the data from the old page to the new 1466 * one and clear the fake/clean flags on the 1467 * new page (keep it busy). force a reload 1468 * of the old page by clearing it from all 1469 * pmaps. then lock the page queues to 1470 * rename the pages. 1471 */ 1472 1473 uvm_pagecopy(uobjpage, pg); /* old -> new */ 1474 pg->flags &= ~(PG_FAKE|PG_CLEAN); 1475 pmap_page_protect(uobjpage, VM_PROT_NONE); 1476 if (uobjpage->flags & PG_WANTED) 1477 wakeup(uobjpage); 1478 /* uobj still locked */ 1479 uobjpage->flags &= ~(PG_WANTED|PG_BUSY); 1480 UVM_PAGE_OWN(uobjpage, NULL); 1481 1482 uvm_lock_pageq(); 1483 offset = uobjpage->offset; 1484 uvm_pagerealloc(uobjpage, NULL, 0); 1485 1486 /* 1487 * at this point we have absolutely no 1488 * control over uobjpage 1489 */ 1490 1491 /* install new page */ 1492 uvm_pageactivate(pg); 1493 uvm_pagerealloc(pg, uobj, offset); 1494 uvm_unlock_pageq(); 1495 1496 /* 1497 * done! loan is broken and "pg" is 1498 * PG_BUSY. it can now replace uobjpage. 1499 */ 1500 1501 uobjpage = pg; 1502 } 1503 } 1504 } else { 1505 1506 /* 1507 * if we are going to promote the data to an anon we 1508 * allocate a blank anon here and plug it into our amap. 1509 */ 1510 #if DIAGNOSTIC 1511 if (amap == NULL) 1512 panic("uvm_fault: want to promote data, but no anon"); 1513 #endif 1514 1515 anon = uvm_analloc(); 1516 if (anon) { 1517 1518 /* 1519 * The new anon is locked. 1520 * 1521 * In `Fill in data...' below, if 1522 * uobjpage == PGO_DONTCARE, we want 1523 * a zero'd, dirty page, so have 1524 * uvm_pagealloc() do that for us. 1525 */ 1526 1527 pg = uvm_pagealloc(NULL, 0, anon, 1528 (uobjpage == PGO_DONTCARE) ? UVM_PGA_ZERO : 0); 1529 } 1530 1531 /* 1532 * out of memory resources? 1533 */ 1534 1535 if (anon == NULL || pg == NULL) { 1536 if (anon != NULL) { 1537 anon->an_ref--; 1538 simple_unlock(&anon->an_lock); 1539 uvm_anfree(anon); 1540 } 1541 1542 /* 1543 * arg! must unbusy our page and fail or sleep. 1544 */ 1545 1546 if (uobjpage != PGO_DONTCARE) { 1547 if (uobjpage->flags & PG_WANTED) 1548 /* still holding object lock */ 1549 wakeup(uobjpage); 1550 1551 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1552 UVM_PAGE_OWN(uobjpage, NULL); 1553 } 1554 1555 /* unlock and fail ... */ 1556 uvmfault_unlockall(&ufi, amap, uobj, NULL); 1557 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 1558 if (anon == NULL || uvmexp.swpgonly == uvmexp.swpages) { 1559 UVMHIST_LOG(maphist, " promote: out of VM", 1560 0,0,0,0); 1561 uvmexp.fltnoanon++; 1562 return ENOMEM; 1563 } 1564 1565 UVMHIST_LOG(maphist, " out of RAM, waiting for more", 1566 0,0,0,0); 1567 uvmexp.fltnoram++; 1568 uvm_wait("flt_noram5"); 1569 goto ReFault; 1570 } 1571 1572 /* 1573 * fill in the data 1574 */ 1575 1576 if (uobjpage != PGO_DONTCARE) { 1577 uvmexp.flt_prcopy++; 1578 /* copy page [pg now dirty] */ 1579 uvm_pagecopy(uobjpage, pg); 1580 1581 /* 1582 * promote to shared amap? make sure all sharing 1583 * procs see it 1584 */ 1585 1586 if ((amap_flags(amap) & AMAP_SHARED) != 0) { 1587 pmap_page_protect(uobjpage, VM_PROT_NONE); 1588 /* 1589 * XXX: PAGE MIGHT BE WIRED! 1590 */ 1591 } 1592 1593 /* 1594 * dispose of uobjpage. it can't be PG_RELEASED 1595 * since we still hold the object lock. 1596 * drop handle to uobj as well. 1597 */ 1598 1599 if (uobjpage->flags & PG_WANTED) 1600 /* still have the obj lock */ 1601 wakeup(uobjpage); 1602 uobjpage->flags &= ~(PG_BUSY|PG_WANTED); 1603 UVM_PAGE_OWN(uobjpage, NULL); 1604 simple_unlock(&uobj->vmobjlock); 1605 uobj = NULL; 1606 1607 UVMHIST_LOG(maphist, 1608 " promote uobjpage 0x%x to anon/page 0x%x/0x%x", 1609 uobjpage, anon, pg, 0); 1610 1611 } else { 1612 uvmexp.flt_przero++; 1613 1614 /* 1615 * Page is zero'd and marked dirty by uvm_pagealloc() 1616 * above. 1617 */ 1618 1619 UVMHIST_LOG(maphist," zero fill anon/page 0x%x/0%x", 1620 anon, pg, 0, 0); 1621 } 1622 amap_add(&ufi.entry->aref, ufi.orig_rvaddr - ufi.entry->start, 1623 anon, 0); 1624 } 1625 1626 /* 1627 * locked: 1628 * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj), 1629 * anon(if !null), pg(if anon) 1630 * 1631 * note: pg is either the uobjpage or the new page in the new anon 1632 */ 1633 1634 /* 1635 * all resources are present. we can now map it in and free our 1636 * resources. 1637 */ 1638 1639 UVMHIST_LOG(maphist, 1640 " MAPPING: case2: pm=0x%x, va=0x%x, pg=0x%x, promote=%d", 1641 ufi.orig_map->pmap, ufi.orig_rvaddr, pg, promote); 1642 KASSERT(access_type == VM_PROT_READ || (pg->flags & PG_RDONLY) == 0); 1643 if (pmap_enter(ufi.orig_map->pmap, ufi.orig_rvaddr, VM_PAGE_TO_PHYS(pg), 1644 pg->flags & PG_RDONLY ? VM_PROT_READ : enter_prot, 1645 access_type | PMAP_CANFAIL | (wired ? PMAP_WIRED : 0)) != 0) { 1646 1647 /* 1648 * No need to undo what we did; we can simply think of 1649 * this as the pmap throwing away the mapping information. 1650 * 1651 * We do, however, have to go through the ReFault path, 1652 * as the map may change while we're asleep. 1653 */ 1654 1655 if (pg->flags & PG_WANTED) 1656 wakeup(pg); 1657 1658 /* 1659 * note that pg can't be PG_RELEASED since we did not drop 1660 * the object lock since the last time we checked. 1661 */ 1662 1663 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 1664 UVM_PAGE_OWN(pg, NULL); 1665 uvmfault_unlockall(&ufi, amap, uobj, anon); 1666 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 1667 if (uvmexp.swpgonly == uvmexp.swpages) { 1668 UVMHIST_LOG(maphist, 1669 "<- failed. out of VM",0,0,0,0); 1670 /* XXX instrumentation */ 1671 return ENOMEM; 1672 } 1673 /* XXX instrumentation */ 1674 uvm_wait("flt_pmfail2"); 1675 goto ReFault; 1676 } 1677 1678 uvm_lock_pageq(); 1679 if (wire_fault) { 1680 uvm_pagewire(pg); 1681 if (pg->pqflags & PQ_AOBJ) { 1682 1683 /* 1684 * since the now-wired page cannot be paged out, 1685 * release its swap resources for others to use. 1686 * since an aobj page with no swap cannot be PG_CLEAN, 1687 * clear its clean flag now. 1688 */ 1689 1690 pg->flags &= ~(PG_CLEAN); 1691 uao_dropswap(uobj, pg->offset >> PAGE_SHIFT); 1692 } 1693 } else { 1694 uvm_pageactivate(pg); 1695 } 1696 uvm_unlock_pageq(); 1697 if (pg->flags & PG_WANTED) 1698 wakeup(pg); 1699 1700 /* 1701 * note that pg can't be PG_RELEASED since we did not drop the object 1702 * lock since the last time we checked. 1703 */ 1704 1705 pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); 1706 UVM_PAGE_OWN(pg, NULL); 1707 uvmfault_unlockall(&ufi, amap, uobj, anon); 1708 pmap_update(ufi.orig_map->pmap); 1709 UVMHIST_LOG(maphist, "<- done (SUCCESS!)",0,0,0,0); 1710 return 0; 1711 } 1712 1713 /* 1714 * uvm_fault_wire: wire down a range of virtual addresses in a map. 1715 * 1716 * => map may be read-locked by caller, but MUST NOT be write-locked. 1717 * => if map is read-locked, any operations which may cause map to 1718 * be write-locked in uvm_fault() must be taken care of by 1719 * the caller. See uvm_map_pageable(). 1720 */ 1721 1722 int 1723 uvm_fault_wire(map, start, end, fault_type, access_type) 1724 struct vm_map *map; 1725 vaddr_t start, end; 1726 vm_fault_t fault_type; 1727 vm_prot_t access_type; 1728 { 1729 vaddr_t va; 1730 int error; 1731 1732 /* 1733 * now fault it in a page at a time. if the fault fails then we have 1734 * to undo what we have done. note that in uvm_fault VM_PROT_NONE 1735 * is replaced with the max protection if fault_type is VM_FAULT_WIRE. 1736 */ 1737 1738 /* 1739 * XXX work around overflowing a vaddr_t. this prevents us from 1740 * wiring the last page in the address space, though. 1741 */ 1742 if (start > end) { 1743 return EFAULT; 1744 } 1745 1746 for (va = start ; va < end ; va += PAGE_SIZE) { 1747 error = uvm_fault(map, va, fault_type, access_type); 1748 if (error) { 1749 if (va != start) { 1750 uvm_fault_unwire(map, start, va); 1751 } 1752 return error; 1753 } 1754 } 1755 return 0; 1756 } 1757 1758 /* 1759 * uvm_fault_unwire(): unwire range of virtual space. 1760 */ 1761 1762 void 1763 uvm_fault_unwire(map, start, end) 1764 struct vm_map *map; 1765 vaddr_t start, end; 1766 { 1767 vm_map_lock_read(map); 1768 uvm_fault_unwire_locked(map, start, end); 1769 vm_map_unlock_read(map); 1770 } 1771 1772 /* 1773 * uvm_fault_unwire_locked(): the guts of uvm_fault_unwire(). 1774 * 1775 * => map must be at least read-locked. 1776 */ 1777 1778 void 1779 uvm_fault_unwire_locked(map, start, end) 1780 struct vm_map *map; 1781 vaddr_t start, end; 1782 { 1783 struct vm_map_entry *entry; 1784 pmap_t pmap = vm_map_pmap(map); 1785 vaddr_t va; 1786 paddr_t pa; 1787 struct vm_page *pg; 1788 1789 KASSERT((map->flags & VM_MAP_INTRSAFE) == 0); 1790 1791 /* 1792 * we assume that the area we are unwiring has actually been wired 1793 * in the first place. this means that we should be able to extract 1794 * the PAs from the pmap. we also lock out the page daemon so that 1795 * we can call uvm_pageunwire. 1796 */ 1797 1798 uvm_lock_pageq(); 1799 1800 /* 1801 * find the beginning map entry for the region. 1802 */ 1803 1804 KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map)); 1805 if (uvm_map_lookup_entry(map, start, &entry) == FALSE) 1806 panic("uvm_fault_unwire_locked: address not in map"); 1807 1808 for (va = start; va < end; va += PAGE_SIZE) { 1809 if (pmap_extract(pmap, va, &pa) == FALSE) 1810 continue; 1811 1812 /* 1813 * find the map entry for the current address. 1814 */ 1815 1816 KASSERT(va >= entry->start); 1817 while (va >= entry->end) { 1818 KASSERT(entry->next != &map->header && 1819 entry->next->start <= entry->end); 1820 entry = entry->next; 1821 } 1822 1823 /* 1824 * if the entry is no longer wired, tell the pmap. 1825 */ 1826 1827 if (VM_MAPENT_ISWIRED(entry) == 0) 1828 pmap_unwire(pmap, va); 1829 1830 pg = PHYS_TO_VM_PAGE(pa); 1831 if (pg) 1832 uvm_pageunwire(pg); 1833 } 1834 1835 uvm_unlock_pageq(); 1836 } 1837