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sys/uvm/uvm_fault.c
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1 /* $OpenBSD: uvm_fault.c,v 1.133 2022/11/04 09:36:44 mpi Exp $ */ 2 /* $NetBSD: uvm_fault.c,v 1.51 2000/08/06 00:22:53 thorpej Exp $ */ 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 * 17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 * 28 * from: Id: uvm_fault.c,v 1.1.2.23 1998/02/06 05:29:05 chs Exp 29 */ 30 31 /* 32 * uvm_fault.c: fault handler 33 */ 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/kernel.h> 38 #include <sys/percpu.h> 39 #include <sys/proc.h> 40 #include <sys/malloc.h> 41 #include <sys/mman.h> 42 #include <sys/tracepoint.h> 43 44 #include <uvm/uvm.h> 45 46 /* 47 * 48 * a word on page faults: 49 * 50 * types of page faults we handle: 51 * 52 * CASE 1: upper layer faults CASE 2: lower layer faults 53 * 54 * CASE 1A CASE 1B CASE 2A CASE 2B 55 * read/write1 write>1 read/write +-cow_write/zero 56 * | | | | 57 * +--|--+ +--|--+ +-----+ + | + | +-----+ 58 * amap | V | | ---------> new | | | | ^ | 59 * +-----+ +-----+ +-----+ + | + | +--|--+ 60 * | | | 61 * +-----+ +-----+ +--|--+ | +--|--+ 62 * uobj | d/c | | d/c | | V | +----+ | 63 * +-----+ +-----+ +-----+ +-----+ 64 * 65 * d/c = don't care 66 * 67 * case [0]: layerless fault 68 * no amap or uobj is present. this is an error. 69 * 70 * case [1]: upper layer fault [anon active] 71 * 1A: [read] or [write with anon->an_ref == 1] 72 * I/O takes place in upper level anon and uobj is not touched. 73 * 1B: [write with anon->an_ref > 1] 74 * new anon is alloc'd and data is copied off ["COW"] 75 * 76 * case [2]: lower layer fault [uobj] 77 * 2A: [read on non-NULL uobj] or [write to non-copy_on_write area] 78 * I/O takes place directly in object. 79 * 2B: [write to copy_on_write] or [read on NULL uobj] 80 * data is "promoted" from uobj to a new anon. 81 * if uobj is null, then we zero fill. 82 * 83 * we follow the standard UVM locking protocol ordering: 84 * 85 * MAPS => AMAP => UOBJ => ANON => PAGE QUEUES (PQ) 86 * we hold a PG_BUSY page if we unlock for I/O 87 * 88 * 89 * the code is structured as follows: 90 * 91 * - init the "IN" params in the ufi structure 92 * ReFault: (ERESTART returned to the loop in uvm_fault) 93 * - do lookups [locks maps], check protection, handle needs_copy 94 * - check for case 0 fault (error) 95 * - establish "range" of fault 96 * - if we have an amap lock it and extract the anons 97 * - if sequential advice deactivate pages behind us 98 * - at the same time check pmap for unmapped areas and anon for pages 99 * that we could map in (and do map it if found) 100 * - check object for resident pages that we could map in 101 * - if (case 2) goto Case2 102 * - >>> handle case 1 103 * - ensure source anon is resident in RAM 104 * - if case 1B alloc new anon and copy from source 105 * - map the correct page in 106 * Case2: 107 * - >>> handle case 2 108 * - ensure source page is resident (if uobj) 109 * - if case 2B alloc new anon and copy from source (could be zero 110 * fill if uobj == NULL) 111 * - map the correct page in 112 * - done! 113 * 114 * note on paging: 115 * if we have to do I/O we place a PG_BUSY page in the correct object, 116 * unlock everything, and do the I/O. when I/O is done we must reverify 117 * the state of the world before assuming that our data structures are 118 * valid. [because mappings could change while the map is unlocked] 119 * 120 * alternative 1: unbusy the page in question and restart the page fault 121 * from the top (ReFault). this is easy but does not take advantage 122 * of the information that we already have from our previous lookup, 123 * although it is possible that the "hints" in the vm_map will help here. 124 * 125 * alternative 2: the system already keeps track of a "version" number of 126 * a map. [i.e. every time you write-lock a map (e.g. to change a 127 * mapping) you bump the version number up by one...] so, we can save 128 * the version number of the map before we release the lock and start I/O. 129 * then when I/O is done we can relock and check the version numbers 130 * to see if anything changed. this might save us some over 1 because 131 * we don't have to unbusy the page and may be less compares(?). 132 * 133 * alternative 3: put in backpointers or a way to "hold" part of a map 134 * in place while I/O is in progress. this could be complex to 135 * implement (especially with structures like amap that can be referenced 136 * by multiple map entries, and figuring out what should wait could be 137 * complex as well...). 138 * 139 * we use alternative 2. given that we are multi-threaded now we may want 140 * to reconsider the choice. 141 */ 142 143 /* 144 * local data structures 145 */ 146 struct uvm_advice { 147 int nback; 148 int nforw; 149 }; 150 151 /* 152 * page range array: set up in uvmfault_init(). 153 */ 154 static struct uvm_advice uvmadvice[MADV_MASK + 1]; 155 156 #define UVM_MAXRANGE 16 /* must be max() of nback+nforw+1 */ 157 158 /* 159 * private prototypes 160 */ 161 static void uvmfault_amapcopy(struct uvm_faultinfo *); 162 static inline void uvmfault_anonflush(struct vm_anon **, int); 163 void uvmfault_unlockmaps(struct uvm_faultinfo *, boolean_t); 164 void uvmfault_update_stats(struct uvm_faultinfo *); 165 166 /* 167 * inline functions 168 */ 169 /* 170 * uvmfault_anonflush: try and deactivate pages in specified anons 171 * 172 * => does not have to deactivate page if it is busy 173 */ 174 static inline void 175 uvmfault_anonflush(struct vm_anon **anons, int n) 176 { 177 int lcv; 178 struct vm_page *pg; 179 180 for (lcv = 0; lcv < n; lcv++) { 181 if (anons[lcv] == NULL) 182 continue; 183 KASSERT(rw_lock_held(anons[lcv]->an_lock)); 184 pg = anons[lcv]->an_page; 185 if (pg && (pg->pg_flags & PG_BUSY) == 0) { 186 uvm_lock_pageq(); 187 if (pg->wire_count == 0) { 188 pmap_page_protect(pg, PROT_NONE); 189 uvm_pagedeactivate(pg); 190 } 191 uvm_unlock_pageq(); 192 } 193 } 194 } 195 196 /* 197 * normal functions 198 */ 199 /* 200 * uvmfault_init: compute proper values for the uvmadvice[] array. 201 */ 202 void 203 uvmfault_init(void) 204 { 205 int npages; 206 207 npages = atop(16384); 208 if (npages > 0) { 209 KASSERT(npages <= UVM_MAXRANGE / 2); 210 uvmadvice[MADV_NORMAL].nforw = npages; 211 uvmadvice[MADV_NORMAL].nback = npages - 1; 212 } 213 214 npages = atop(32768); 215 if (npages > 0) { 216 KASSERT(npages <= UVM_MAXRANGE / 2); 217 uvmadvice[MADV_SEQUENTIAL].nforw = npages - 1; 218 uvmadvice[MADV_SEQUENTIAL].nback = npages; 219 } 220 } 221 222 /* 223 * uvmfault_amapcopy: clear "needs_copy" in a map. 224 * 225 * => called with VM data structures unlocked (usually, see below) 226 * => we get a write lock on the maps and clear needs_copy for a VA 227 * => if we are out of RAM we sleep (waiting for more) 228 */ 229 static void 230 uvmfault_amapcopy(struct uvm_faultinfo *ufi) 231 { 232 for (;;) { 233 /* 234 * no mapping? give up. 235 */ 236 if (uvmfault_lookup(ufi, TRUE) == FALSE) 237 return; 238 239 /* 240 * copy if needed. 241 */ 242 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) 243 amap_copy(ufi->map, ufi->entry, M_NOWAIT, 244 UVM_ET_ISSTACK(ufi->entry) ? FALSE : TRUE, 245 ufi->orig_rvaddr, ufi->orig_rvaddr + 1); 246 247 /* 248 * didn't work? must be out of RAM. unlock and sleep. 249 */ 250 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 251 uvmfault_unlockmaps(ufi, TRUE); 252 uvm_wait("fltamapcopy"); 253 continue; 254 } 255 256 /* 257 * got it! unlock and return. 258 */ 259 uvmfault_unlockmaps(ufi, TRUE); 260 return; 261 } 262 /*NOTREACHED*/ 263 } 264 265 /* 266 * uvmfault_anonget: get data in an anon into a non-busy, non-released 267 * page in that anon. 268 * 269 * => Map, amap and thus anon should be locked by caller. 270 * => If we fail, we unlock everything and error is returned. 271 * => If we are successful, return with everything still locked. 272 * => We do not move the page on the queues [gets moved later]. If we 273 * allocate a new page [we_own], it gets put on the queues. Either way, 274 * the result is that the page is on the queues at return time 275 */ 276 int 277 uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap, 278 struct vm_anon *anon) 279 { 280 struct vm_page *pg; 281 int error; 282 283 KASSERT(rw_lock_held(anon->an_lock)); 284 KASSERT(anon->an_lock == amap->am_lock); 285 286 /* Increment the counters.*/ 287 counters_inc(uvmexp_counters, flt_anget); 288 if (anon->an_page) { 289 curproc->p_ru.ru_minflt++; 290 } else { 291 curproc->p_ru.ru_majflt++; 292 } 293 error = 0; 294 295 /* 296 * Loop until we get the anon data, or fail. 297 */ 298 for (;;) { 299 boolean_t we_own, locked; 300 /* 301 * Note: 'we_own' will become true if we set PG_BUSY on a page. 302 */ 303 we_own = FALSE; 304 pg = anon->an_page; 305 306 /* 307 * Is page resident? Make sure it is not busy/released. 308 */ 309 if (pg) { 310 KASSERT(pg->pg_flags & PQ_ANON); 311 KASSERT(pg->uanon == anon); 312 313 /* 314 * if the page is busy, we drop all the locks and 315 * try again. 316 */ 317 if ((pg->pg_flags & (PG_BUSY|PG_RELEASED)) == 0) 318 return (VM_PAGER_OK); 319 atomic_setbits_int(&pg->pg_flags, PG_WANTED); 320 counters_inc(uvmexp_counters, flt_pgwait); 321 322 /* 323 * The last unlock must be an atomic unlock and wait 324 * on the owner of page. 325 */ 326 if (pg->uobject) { 327 /* Owner of page is UVM object. */ 328 uvmfault_unlockall(ufi, amap, NULL); 329 rwsleep_nsec(pg, pg->uobject->vmobjlock, 330 PVM | PNORELOCK, "anonget1", INFSLP); 331 } else { 332 /* Owner of page is anon. */ 333 uvmfault_unlockall(ufi, NULL, NULL); 334 rwsleep_nsec(pg, anon->an_lock, PVM | PNORELOCK, 335 "anonget2", INFSLP); 336 } 337 } else { 338 /* 339 * No page, therefore allocate one. 340 */ 341 pg = uvm_pagealloc(NULL, 0, anon, 0); 342 if (pg == NULL) { 343 /* Out of memory. Wait a little. */ 344 uvmfault_unlockall(ufi, amap, NULL); 345 counters_inc(uvmexp_counters, flt_noram); 346 uvm_wait("flt_noram1"); 347 } else { 348 /* PG_BUSY bit is set. */ 349 we_own = TRUE; 350 uvmfault_unlockall(ufi, amap, NULL); 351 352 /* 353 * Pass a PG_BUSY+PG_FAKE+PG_CLEAN page into 354 * the uvm_swap_get() function with all data 355 * structures unlocked. Note that it is OK 356 * to read an_swslot here, because we hold 357 * PG_BUSY on the page. 358 */ 359 counters_inc(uvmexp_counters, pageins); 360 error = uvm_swap_get(pg, anon->an_swslot, 361 PGO_SYNCIO); 362 363 /* 364 * We clean up after the I/O below in the 365 * 'we_own' case. 366 */ 367 } 368 } 369 370 /* 371 * Re-lock the map and anon. 372 */ 373 locked = uvmfault_relock(ufi); 374 if (locked || we_own) { 375 rw_enter(anon->an_lock, RW_WRITE); 376 } 377 378 /* 379 * If we own the page (i.e. we set PG_BUSY), then we need 380 * to clean up after the I/O. There are three cases to 381 * consider: 382 * 383 * 1) Page was released during I/O: free anon and ReFault. 384 * 2) I/O not OK. Free the page and cause the fault to fail. 385 * 3) I/O OK! Activate the page and sync with the non-we_own 386 * case (i.e. drop anon lock if not locked). 387 */ 388 if (we_own) { 389 if (pg->pg_flags & PG_WANTED) { 390 wakeup(pg); 391 } 392 393 /* 394 * if we were RELEASED during I/O, then our anon is 395 * no longer part of an amap. we need to free the 396 * anon and try again. 397 */ 398 if (pg->pg_flags & PG_RELEASED) { 399 pmap_page_protect(pg, PROT_NONE); 400 KASSERT(anon->an_ref == 0); 401 /* 402 * Released while we had unlocked amap. 403 */ 404 if (locked) 405 uvmfault_unlockall(ufi, NULL, NULL); 406 uvm_anon_release(anon); /* frees page for us */ 407 counters_inc(uvmexp_counters, flt_pgrele); 408 return (VM_PAGER_REFAULT); /* refault! */ 409 } 410 411 if (error != VM_PAGER_OK) { 412 KASSERT(error != VM_PAGER_PEND); 413 414 /* remove page from anon */ 415 anon->an_page = NULL; 416 417 /* 418 * Remove the swap slot from the anon and 419 * mark the anon as having no real slot. 420 * Do not free the swap slot, thus preventing 421 * it from being used again. 422 */ 423 uvm_swap_markbad(anon->an_swslot, 1); 424 anon->an_swslot = SWSLOT_BAD; 425 426 /* 427 * Note: page was never !PG_BUSY, so it 428 * cannot be mapped and thus no need to 429 * pmap_page_protect() it. 430 */ 431 uvm_lock_pageq(); 432 uvm_pagefree(pg); 433 uvm_unlock_pageq(); 434 435 if (locked) { 436 uvmfault_unlockall(ufi, NULL, NULL); 437 } 438 rw_exit(anon->an_lock); 439 return (VM_PAGER_ERROR); 440 } 441 442 /* 443 * We have successfully read the page, activate it. 444 */ 445 pmap_clear_modify(pg); 446 uvm_lock_pageq(); 447 uvm_pageactivate(pg); 448 uvm_unlock_pageq(); 449 atomic_clearbits_int(&pg->pg_flags, 450 PG_WANTED|PG_BUSY|PG_FAKE); 451 UVM_PAGE_OWN(pg, NULL); 452 } 453 454 /* 455 * We were not able to re-lock the map - restart the fault. 456 */ 457 if (!locked) { 458 if (we_own) { 459 rw_exit(anon->an_lock); 460 } 461 return (VM_PAGER_REFAULT); 462 } 463 464 /* 465 * Verify that no one has touched the amap and moved 466 * the anon on us. 467 */ 468 if (ufi != NULL && amap_lookup(&ufi->entry->aref, 469 ufi->orig_rvaddr - ufi->entry->start) != anon) { 470 471 uvmfault_unlockall(ufi, amap, NULL); 472 return (VM_PAGER_REFAULT); 473 } 474 475 /* 476 * Retry.. 477 */ 478 counters_inc(uvmexp_counters, flt_anretry); 479 continue; 480 481 } 482 /*NOTREACHED*/ 483 } 484 485 /* 486 * Update statistics after fault resolution. 487 * - maxrss 488 */ 489 void 490 uvmfault_update_stats(struct uvm_faultinfo *ufi) 491 { 492 struct vm_map *map; 493 struct proc *p; 494 vsize_t res; 495 496 map = ufi->orig_map; 497 498 /* 499 * If this is a nested pmap (eg, a virtual machine pmap managed 500 * by vmm(4) on amd64/i386), don't do any updating, just return. 501 * 502 * pmap_nested() on other archs is #defined to 0, so this is a 503 * no-op. 504 */ 505 if (pmap_nested(map->pmap)) 506 return; 507 508 /* Update the maxrss for the process. */ 509 if (map->flags & VM_MAP_ISVMSPACE) { 510 p = curproc; 511 KASSERT(p != NULL && &p->p_vmspace->vm_map == map); 512 513 res = pmap_resident_count(map->pmap); 514 /* Convert res from pages to kilobytes. */ 515 res <<= (PAGE_SHIFT - 10); 516 517 if (p->p_ru.ru_maxrss < res) 518 p->p_ru.ru_maxrss = res; 519 } 520 } 521 522 /* 523 * F A U L T - m a i n e n t r y p o i n t 524 */ 525 526 /* 527 * uvm_fault: page fault handler 528 * 529 * => called from MD code to resolve a page fault 530 * => VM data structures usually should be unlocked. however, it is 531 * possible to call here with the main map locked if the caller 532 * gets a write lock, sets it recursive, and then calls us (c.f. 533 * uvm_map_pageable). this should be avoided because it keeps 534 * the map locked off during I/O. 535 * => MUST NEVER BE CALLED IN INTERRUPT CONTEXT 536 */ 537 #define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \ 538 ~PROT_WRITE : PROT_MASK) 539 struct uvm_faultctx { 540 /* 541 * the following members are set up by uvm_fault_check() and 542 * read-only after that. 543 */ 544 vm_prot_t enter_prot; 545 vm_prot_t access_type; 546 vaddr_t startva; 547 int npages; 548 int centeridx; 549 boolean_t narrow; 550 boolean_t wired; 551 paddr_t pa_flags; 552 }; 553 554 int uvm_fault_check( 555 struct uvm_faultinfo *, struct uvm_faultctx *, 556 struct vm_anon ***); 557 558 int uvm_fault_upper( 559 struct uvm_faultinfo *, struct uvm_faultctx *, 560 struct vm_anon **, vm_fault_t); 561 boolean_t uvm_fault_upper_lookup( 562 struct uvm_faultinfo *, const struct uvm_faultctx *, 563 struct vm_anon **, struct vm_page **); 564 565 int uvm_fault_lower( 566 struct uvm_faultinfo *, struct uvm_faultctx *, 567 struct vm_page **, vm_fault_t); 568 569 int 570 uvm_fault(vm_map_t orig_map, vaddr_t vaddr, vm_fault_t fault_type, 571 vm_prot_t access_type) 572 { 573 struct uvm_faultinfo ufi; 574 struct uvm_faultctx flt; 575 boolean_t shadowed; 576 struct vm_anon *anons_store[UVM_MAXRANGE], **anons; 577 struct vm_page *pages[UVM_MAXRANGE]; 578 int error; 579 580 counters_inc(uvmexp_counters, faults); 581 TRACEPOINT(uvm, fault, vaddr, fault_type, access_type, NULL); 582 583 /* 584 * init the IN parameters in the ufi 585 */ 586 ufi.orig_map = orig_map; 587 ufi.orig_rvaddr = trunc_page(vaddr); 588 ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */ 589 if (fault_type == VM_FAULT_WIRE) 590 flt.narrow = TRUE; /* don't look for neighborhood 591 * pages on wire */ 592 else 593 flt.narrow = FALSE; /* normal fault */ 594 flt.access_type = access_type; 595 596 597 error = ERESTART; 598 while (error == ERESTART) { /* ReFault: */ 599 anons = anons_store; 600 601 error = uvm_fault_check(&ufi, &flt, &anons); 602 if (error != 0) 603 continue; 604 605 /* True if there is an anon at the faulting address */ 606 shadowed = uvm_fault_upper_lookup(&ufi, &flt, anons, pages); 607 if (shadowed == TRUE) { 608 /* case 1: fault on an anon in our amap */ 609 error = uvm_fault_upper(&ufi, &flt, anons, fault_type); 610 } else { 611 struct uvm_object *uobj = ufi.entry->object.uvm_obj; 612 613 /* 614 * if the desired page is not shadowed by the amap and 615 * we have a backing object, then we check to see if 616 * the backing object would prefer to handle the fault 617 * itself (rather than letting us do it with the usual 618 * pgo_get hook). the backing object signals this by 619 * providing a pgo_fault routine. 620 */ 621 if (uobj != NULL && uobj->pgops->pgo_fault != NULL) { 622 KERNEL_LOCK(); 623 rw_enter(uobj->vmobjlock, RW_WRITE); 624 error = uobj->pgops->pgo_fault(&ufi, 625 flt.startva, pages, flt.npages, 626 flt.centeridx, fault_type, flt.access_type, 627 PGO_LOCKED); 628 KERNEL_UNLOCK(); 629 630 if (error == VM_PAGER_OK) 631 error = 0; 632 else if (error == VM_PAGER_REFAULT) 633 error = ERESTART; 634 else 635 error = EACCES; 636 } else { 637 /* case 2: fault on backing obj or zero fill */ 638 error = uvm_fault_lower(&ufi, &flt, pages, 639 fault_type); 640 } 641 } 642 } 643 644 return error; 645 } 646 647 /* 648 * uvm_fault_check: check prot, handle needs-copy, etc. 649 * 650 * 1. lookup entry. 651 * 2. check protection. 652 * 3. adjust fault condition (mainly for simulated fault). 653 * 4. handle needs-copy (lazy amap copy). 654 * 5. establish range of interest for neighbor fault (aka pre-fault). 655 * 6. look up anons (if amap exists). 656 * 7. flush pages (if MADV_SEQUENTIAL) 657 * 658 * => called with nothing locked. 659 * => if we fail (result != 0) we unlock everything. 660 * => initialize/adjust many members of flt. 661 */ 662 int 663 uvm_fault_check(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 664 struct vm_anon ***ranons) 665 { 666 struct vm_amap *amap; 667 struct uvm_object *uobj; 668 int nback, nforw; 669 670 /* 671 * lookup and lock the maps 672 */ 673 if (uvmfault_lookup(ufi, FALSE) == FALSE) { 674 return EFAULT; 675 } 676 /* locked: maps(read) */ 677 678 #ifdef DIAGNOSTIC 679 if ((ufi->map->flags & VM_MAP_PAGEABLE) == 0) 680 panic("uvm_fault: fault on non-pageable map (%p, 0x%lx)", 681 ufi->map, ufi->orig_rvaddr); 682 #endif 683 684 /* 685 * check protection 686 */ 687 if ((ufi->entry->protection & flt->access_type) != flt->access_type) { 688 uvmfault_unlockmaps(ufi, FALSE); 689 return EACCES; 690 } 691 692 /* 693 * "enter_prot" is the protection we want to enter the page in at. 694 * for certain pages (e.g. copy-on-write pages) this protection can 695 * be more strict than ufi->entry->protection. "wired" means either 696 * the entry is wired or we are fault-wiring the pg. 697 */ 698 699 flt->enter_prot = ufi->entry->protection; 700 flt->pa_flags = UVM_ET_ISWC(ufi->entry) ? PMAP_WC : 0; 701 flt->wired = VM_MAPENT_ISWIRED(ufi->entry) || (flt->narrow == TRUE); 702 if (flt->wired) 703 flt->access_type = flt->enter_prot; /* full access for wired */ 704 705 /* handle "needs_copy" case. */ 706 if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { 707 if ((flt->access_type & PROT_WRITE) || 708 (ufi->entry->object.uvm_obj == NULL)) { 709 /* need to clear */ 710 uvmfault_unlockmaps(ufi, FALSE); 711 uvmfault_amapcopy(ufi); 712 counters_inc(uvmexp_counters, flt_amcopy); 713 return ERESTART; 714 } else { 715 /* 716 * ensure that we pmap_enter page R/O since 717 * needs_copy is still true 718 */ 719 flt->enter_prot &= ~PROT_WRITE; 720 } 721 } 722 723 /* 724 * identify the players 725 */ 726 amap = ufi->entry->aref.ar_amap; /* upper layer */ 727 uobj = ufi->entry->object.uvm_obj; /* lower layer */ 728 729 /* 730 * check for a case 0 fault. if nothing backing the entry then 731 * error now. 732 */ 733 if (amap == NULL && uobj == NULL) { 734 uvmfault_unlockmaps(ufi, FALSE); 735 return EFAULT; 736 } 737 738 /* 739 * for a case 2B fault waste no time on adjacent pages because 740 * they are likely already entered. 741 */ 742 if (uobj != NULL && amap != NULL && 743 (flt->access_type & PROT_WRITE) != 0) { 744 /* wide fault (!narrow) */ 745 flt->narrow = TRUE; 746 } 747 748 /* 749 * establish range of interest based on advice from mapper 750 * and then clip to fit map entry. note that we only want 751 * to do this the first time through the fault. if we 752 * ReFault we will disable this by setting "narrow" to true. 753 */ 754 if (flt->narrow == FALSE) { 755 756 /* wide fault (!narrow) */ 757 nback = min(uvmadvice[ufi->entry->advice].nback, 758 (ufi->orig_rvaddr - ufi->entry->start) >> PAGE_SHIFT); 759 flt->startva = ufi->orig_rvaddr - ((vsize_t)nback << PAGE_SHIFT); 760 nforw = min(uvmadvice[ufi->entry->advice].nforw, 761 ((ufi->entry->end - ufi->orig_rvaddr) >> PAGE_SHIFT) - 1); 762 /* 763 * note: "-1" because we don't want to count the 764 * faulting page as forw 765 */ 766 flt->npages = nback + nforw + 1; 767 flt->centeridx = nback; 768 769 flt->narrow = TRUE; /* ensure only once per-fault */ 770 } else { 771 /* narrow fault! */ 772 nback = nforw = 0; 773 flt->startva = ufi->orig_rvaddr; 774 flt->npages = 1; 775 flt->centeridx = 0; 776 } 777 778 /* 779 * if we've got an amap then lock it and extract current anons. 780 */ 781 if (amap) { 782 amap_lock(amap); 783 amap_lookups(&ufi->entry->aref, 784 flt->startva - ufi->entry->start, *ranons, flt->npages); 785 } else { 786 *ranons = NULL; /* to be safe */ 787 } 788 789 /* 790 * for MADV_SEQUENTIAL mappings we want to deactivate the back pages 791 * now and then forget about them (for the rest of the fault). 792 */ 793 if (ufi->entry->advice == MADV_SEQUENTIAL && nback != 0) { 794 /* flush back-page anons? */ 795 if (amap) 796 uvmfault_anonflush(*ranons, nback); 797 798 /* 799 * flush object? 800 */ 801 if (uobj) { 802 voff_t uoff; 803 804 uoff = (flt->startva - ufi->entry->start) + ufi->entry->offset; 805 rw_enter(uobj->vmobjlock, RW_WRITE); 806 (void) uobj->pgops->pgo_flush(uobj, uoff, uoff + 807 ((vsize_t)nback << PAGE_SHIFT), PGO_DEACTIVATE); 808 rw_exit(uobj->vmobjlock); 809 } 810 811 /* now forget about the backpages */ 812 if (amap) 813 *ranons += nback; 814 flt->startva += ((vsize_t)nback << PAGE_SHIFT); 815 flt->npages -= nback; 816 flt->centeridx = 0; 817 } 818 819 return 0; 820 } 821 822 /* 823 * uvm_fault_upper_lookup: look up existing h/w mapping and amap. 824 * 825 * iterate range of interest: 826 * 1. check if h/w mapping exists. if yes, we don't care 827 * 2. check if anon exists. if not, page is lower. 828 * 3. if anon exists, enter h/w mapping for neighbors. 829 * 830 * => called with amap locked (if exists). 831 */ 832 boolean_t 833 uvm_fault_upper_lookup(struct uvm_faultinfo *ufi, 834 const struct uvm_faultctx *flt, struct vm_anon **anons, 835 struct vm_page **pages) 836 { 837 struct vm_amap *amap = ufi->entry->aref.ar_amap; 838 struct vm_anon *anon; 839 boolean_t shadowed; 840 vaddr_t currva; 841 paddr_t pa; 842 int lcv; 843 844 /* locked: maps(read), amap(if there) */ 845 KASSERT(amap == NULL || 846 rw_write_held(amap->am_lock)); 847 848 /* 849 * map in the backpages and frontpages we found in the amap in hopes 850 * of preventing future faults. we also init the pages[] array as 851 * we go. 852 */ 853 currva = flt->startva; 854 shadowed = FALSE; 855 for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { 856 /* 857 * dont play with VAs that are already mapped 858 * except for center) 859 */ 860 if (lcv != flt->centeridx && 861 pmap_extract(ufi->orig_map->pmap, currva, &pa)) { 862 pages[lcv] = PGO_DONTCARE; 863 continue; 864 } 865 866 /* 867 * unmapped or center page. check if any anon at this level. 868 */ 869 if (amap == NULL || anons[lcv] == NULL) { 870 pages[lcv] = NULL; 871 continue; 872 } 873 874 /* 875 * check for present page and map if possible. 876 */ 877 pages[lcv] = PGO_DONTCARE; 878 if (lcv == flt->centeridx) { /* save center for later! */ 879 shadowed = TRUE; 880 continue; 881 } 882 anon = anons[lcv]; 883 KASSERT(anon->an_lock == amap->am_lock); 884 if (anon->an_page && 885 (anon->an_page->pg_flags & (PG_RELEASED|PG_BUSY)) == 0) { 886 uvm_lock_pageq(); 887 uvm_pageactivate(anon->an_page); /* reactivate */ 888 uvm_unlock_pageq(); 889 counters_inc(uvmexp_counters, flt_namap); 890 891 /* 892 * Since this isn't the page that's actually faulting, 893 * ignore pmap_enter() failures; it's not critical 894 * that we enter these right now. 895 */ 896 (void) pmap_enter(ufi->orig_map->pmap, currva, 897 VM_PAGE_TO_PHYS(anon->an_page) | flt->pa_flags, 898 (anon->an_ref > 1) ? 899 (flt->enter_prot & ~PROT_WRITE) : flt->enter_prot, 900 PMAP_CANFAIL | 901 (VM_MAPENT_ISWIRED(ufi->entry) ? PMAP_WIRED : 0)); 902 } 903 } 904 if (flt->npages > 1) 905 pmap_update(ufi->orig_map->pmap); 906 907 return shadowed; 908 } 909 910 /* 911 * uvm_fault_upper: handle upper fault. 912 * 913 * 1. acquire anon lock. 914 * 2. get anon. let uvmfault_anonget do the dirty work. 915 * 3. if COW, promote data to new anon 916 * 4. enter h/w mapping 917 */ 918 int 919 uvm_fault_upper(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 920 struct vm_anon **anons, vm_fault_t fault_type) 921 { 922 struct vm_amap *amap = ufi->entry->aref.ar_amap; 923 struct vm_anon *oanon, *anon = anons[flt->centeridx]; 924 struct vm_page *pg = NULL; 925 int error, ret; 926 927 /* locked: maps(read), amap, anon */ 928 KASSERT(rw_write_held(amap->am_lock)); 929 KASSERT(anon->an_lock == amap->am_lock); 930 931 /* 932 * no matter if we have case 1A or case 1B we are going to need to 933 * have the anon's memory resident. ensure that now. 934 */ 935 /* 936 * let uvmfault_anonget do the dirty work. 937 * if it fails (!OK) it will unlock everything for us. 938 * if it succeeds, locks are still valid and locked. 939 * also, if it is OK, then the anon's page is on the queues. 940 * if the page is on loan from a uvm_object, then anonget will 941 * lock that object for us if it does not fail. 942 */ 943 error = uvmfault_anonget(ufi, amap, anon); 944 switch (error) { 945 case VM_PAGER_OK: 946 break; 947 948 case VM_PAGER_REFAULT: 949 return ERESTART; 950 951 case VM_PAGER_ERROR: 952 /* 953 * An error occurred while trying to bring in the 954 * page -- this is the only error we return right 955 * now. 956 */ 957 return EACCES; /* XXX */ 958 default: 959 #ifdef DIAGNOSTIC 960 panic("uvm_fault: uvmfault_anonget -> %d", error); 961 #else 962 return EACCES; 963 #endif 964 } 965 966 KASSERT(rw_write_held(amap->am_lock)); 967 KASSERT(anon->an_lock == amap->am_lock); 968 969 /* 970 * if we are case 1B then we will need to allocate a new blank 971 * anon to transfer the data into. note that we have a lock 972 * on anon, so no one can busy or release the page until we are done. 973 * also note that the ref count can't drop to zero here because 974 * it is > 1 and we are only dropping one ref. 975 * 976 * in the (hopefully very rare) case that we are out of RAM we 977 * will unlock, wait for more RAM, and refault. 978 * 979 * if we are out of anon VM we wait for RAM to become available. 980 */ 981 982 if ((flt->access_type & PROT_WRITE) != 0 && anon->an_ref > 1) { 983 counters_inc(uvmexp_counters, flt_acow); 984 oanon = anon; /* oanon = old */ 985 anon = uvm_analloc(); 986 if (anon) { 987 anon->an_lock = amap->am_lock; 988 pg = uvm_pagealloc(NULL, 0, anon, 0); 989 } 990 991 /* check for out of RAM */ 992 if (anon == NULL || pg == NULL) { 993 uvmfault_unlockall(ufi, amap, NULL); 994 if (anon == NULL) 995 counters_inc(uvmexp_counters, flt_noanon); 996 else { 997 anon->an_lock = NULL; 998 anon->an_ref--; 999 uvm_anfree(anon); 1000 counters_inc(uvmexp_counters, flt_noram); 1001 } 1002 1003 if (uvm_swapisfull()) 1004 return ENOMEM; 1005 1006 /* out of RAM, wait for more */ 1007 if (anon == NULL) 1008 uvm_anwait(); 1009 else 1010 uvm_wait("flt_noram3"); 1011 return ERESTART; 1012 } 1013 1014 /* got all resources, replace anon with nanon */ 1015 uvm_pagecopy(oanon->an_page, pg); /* pg now !PG_CLEAN */ 1016 /* un-busy! new page */ 1017 atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_FAKE); 1018 UVM_PAGE_OWN(pg, NULL); 1019 ret = amap_add(&ufi->entry->aref, 1020 ufi->orig_rvaddr - ufi->entry->start, anon, 1); 1021 KASSERT(ret == 0); 1022 1023 /* deref: can not drop to zero here by defn! */ 1024 oanon->an_ref--; 1025 1026 #if defined(MULTIPROCESSOR) && !defined(__HAVE_PMAP_MPSAFE_ENTER_COW) 1027 /* 1028 * If there are multiple threads, either uvm or the 1029 * pmap has to make sure no threads see the old RO 1030 * mapping once any have seen the new RW mapping. 1031 * uvm does it by inserting the new mapping RO and 1032 * letting it fault again. 1033 * This is only a problem on MP systems. 1034 */ 1035 if (P_HASSIBLING(curproc)) { 1036 flt->enter_prot &= ~PROT_WRITE; 1037 flt->access_type &= ~PROT_WRITE; 1038 } 1039 #endif 1040 1041 /* 1042 * note: anon is _not_ locked, but we have the sole references 1043 * to in from amap. 1044 * thus, no one can get at it until we are done with it. 1045 */ 1046 } else { 1047 counters_inc(uvmexp_counters, flt_anon); 1048 oanon = anon; 1049 pg = anon->an_page; 1050 if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */ 1051 flt->enter_prot = flt->enter_prot & ~PROT_WRITE; 1052 } 1053 1054 /* 1055 * now map the page in . 1056 */ 1057 if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr, 1058 VM_PAGE_TO_PHYS(pg) | flt->pa_flags, flt->enter_prot, 1059 flt->access_type | PMAP_CANFAIL | (flt->wired ? PMAP_WIRED : 0)) != 0) { 1060 /* 1061 * No need to undo what we did; we can simply think of 1062 * this as the pmap throwing away the mapping information. 1063 * 1064 * We do, however, have to go through the ReFault path, 1065 * as the map may change while we're asleep. 1066 */ 1067 uvmfault_unlockall(ufi, amap, NULL); 1068 if (uvm_swapisfull()) { 1069 /* XXX instrumentation */ 1070 return ENOMEM; 1071 } 1072 /* XXX instrumentation */ 1073 uvm_wait("flt_pmfail1"); 1074 return ERESTART; 1075 } 1076 1077 /* 1078 * ... update the page queues. 1079 */ 1080 uvm_lock_pageq(); 1081 1082 if (fault_type == VM_FAULT_WIRE) { 1083 uvm_pagewire(pg); 1084 /* 1085 * since the now-wired page cannot be paged out, 1086 * release its swap resources for others to use. 1087 * since an anon with no swap cannot be PG_CLEAN, 1088 * clear its clean flag now. 1089 */ 1090 atomic_clearbits_int(&pg->pg_flags, PG_CLEAN); 1091 uvm_anon_dropswap(anon); 1092 } else { 1093 /* activate it */ 1094 uvm_pageactivate(pg); 1095 } 1096 1097 uvm_unlock_pageq(); 1098 1099 /* 1100 * done case 1! finish up by unlocking everything and returning success 1101 */ 1102 uvmfault_unlockall(ufi, amap, NULL); 1103 pmap_update(ufi->orig_map->pmap); 1104 return 0; 1105 } 1106 1107 /* 1108 * uvm_fault_lower_lookup: look up on-memory uobj pages. 1109 * 1110 * 1. get on-memory pages. 1111 * 2. if failed, give up (get only center page later). 1112 * 3. if succeeded, enter h/w mapping of neighbor pages. 1113 */ 1114 1115 struct vm_page * 1116 uvm_fault_lower_lookup( 1117 struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, 1118 struct vm_page **pages) 1119 { 1120 struct uvm_object *uobj = ufi->entry->object.uvm_obj; 1121 struct vm_page *uobjpage = NULL; 1122 int lcv, gotpages; 1123 vaddr_t currva; 1124 1125 rw_enter(uobj->vmobjlock, RW_WRITE); 1126 1127 counters_inc(uvmexp_counters, flt_lget); 1128 gotpages = flt->npages; 1129 (void) uobj->pgops->pgo_get(uobj, 1130 ufi->entry->offset + (flt->startva - ufi->entry->start), 1131 pages, &gotpages, flt->centeridx, 1132 flt->access_type & MASK(ufi->entry), ufi->entry->advice, 1133 PGO_LOCKED); 1134 1135 /* 1136 * check for pages to map, if we got any 1137 */ 1138 if (gotpages == 0) { 1139 return NULL; 1140 } 1141 1142 currva = flt->startva; 1143 for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { 1144 if (pages[lcv] == NULL || 1145 pages[lcv] == PGO_DONTCARE) 1146 continue; 1147 1148 KASSERT((pages[lcv]->pg_flags & PG_RELEASED) == 0); 1149 1150 /* 1151 * if center page is resident and not 1152 * PG_BUSY, then pgo_get made it PG_BUSY 1153 * for us and gave us a handle to it. 1154 * remember this page as "uobjpage." 1155 * (for later use). 1156 */ 1157 if (lcv == flt->centeridx) { 1158 uobjpage = pages[lcv]; 1159 continue; 1160 } 1161 1162 /* 1163 * note: calling pgo_get with locked data 1164 * structures returns us pages which are 1165 * neither busy nor released, so we don't 1166 * need to check for this. we can just 1167 * directly enter the page (after moving it 1168 * to the head of the active queue [useful?]). 1169 */ 1170 1171 uvm_lock_pageq(); 1172 uvm_pageactivate(pages[lcv]); /* reactivate */ 1173 uvm_unlock_pageq(); 1174 counters_inc(uvmexp_counters, flt_nomap); 1175 1176 /* 1177 * Since this page isn't the page that's 1178 * actually faulting, ignore pmap_enter() 1179 * failures; it's not critical that we 1180 * enter these right now. 1181 */ 1182 (void) pmap_enter(ufi->orig_map->pmap, currva, 1183 VM_PAGE_TO_PHYS(pages[lcv]) | flt->pa_flags, 1184 flt->enter_prot & MASK(ufi->entry), 1185 PMAP_CANFAIL | 1186 (flt->wired ? PMAP_WIRED : 0)); 1187 1188 /* 1189 * NOTE: page can't be PG_WANTED because 1190 * we've held the lock the whole time 1191 * we've had the handle. 1192 */ 1193 atomic_clearbits_int(&pages[lcv]->pg_flags, PG_BUSY); 1194 UVM_PAGE_OWN(pages[lcv], NULL); 1195 } 1196 pmap_update(ufi->orig_map->pmap); 1197 1198 return uobjpage; 1199 } 1200 1201 /* 1202 * uvm_fault_lower: handle lower fault. 1203 * 1204 */ 1205 int 1206 uvm_fault_lower(struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, 1207 struct vm_page **pages, vm_fault_t fault_type) 1208 { 1209 struct vm_amap *amap = ufi->entry->aref.ar_amap; 1210 struct uvm_object *uobj = ufi->entry->object.uvm_obj; 1211 boolean_t promote, locked; 1212 int result; 1213 struct vm_page *uobjpage, *pg = NULL; 1214 struct vm_anon *anon = NULL; 1215 voff_t uoff; 1216 1217 /* 1218 * now, if the desired page is not shadowed by the amap and we have 1219 * a backing object that does not have a special fault routine, then 1220 * we ask (with pgo_get) the object for resident pages that we care 1221 * about and attempt to map them in. we do not let pgo_get block 1222 * (PGO_LOCKED). 1223 */ 1224 if (uobj == NULL) { 1225 /* zero fill; don't care neighbor pages */ 1226 uobjpage = NULL; 1227 } else { 1228 uobjpage = uvm_fault_lower_lookup(ufi, flt, pages); 1229 } 1230 1231 /* 1232 * note that at this point we are done with any front or back pages. 1233 * we are now going to focus on the center page (i.e. the one we've 1234 * faulted on). if we have faulted on the bottom (uobj) 1235 * layer [i.e. case 2] and the page was both present and available, 1236 * then we've got a pointer to it as "uobjpage" and we've already 1237 * made it BUSY. 1238 */ 1239 1240 /* 1241 * locked: 1242 */ 1243 KASSERT(amap == NULL || 1244 rw_write_held(amap->am_lock)); 1245 KASSERT(uobj == NULL || 1246 rw_write_held(uobj->vmobjlock)); 1247 1248 /* 1249 * note that uobjpage can not be PGO_DONTCARE at this point. we now 1250 * set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we 1251 * have a backing object, check and see if we are going to promote 1252 * the data up to an anon during the fault. 1253 */ 1254 if (uobj == NULL) { 1255 uobjpage = PGO_DONTCARE; 1256 promote = TRUE; /* always need anon here */ 1257 } else { 1258 KASSERT(uobjpage != PGO_DONTCARE); 1259 promote = (flt->access_type & PROT_WRITE) && 1260 UVM_ET_ISCOPYONWRITE(ufi->entry); 1261 } 1262 1263 /* 1264 * if uobjpage is not null then we do not need to do I/O to get the 1265 * uobjpage. 1266 * 1267 * if uobjpage is null, then we need to ask the pager to 1268 * get the data for us. once we have the data, we need to reverify 1269 * the state the world. we are currently not holding any resources. 1270 */ 1271 if (uobjpage) { 1272 /* update rusage counters */ 1273 curproc->p_ru.ru_minflt++; 1274 } else { 1275 int gotpages; 1276 1277 /* update rusage counters */ 1278 curproc->p_ru.ru_majflt++; 1279 1280 uvmfault_unlockall(ufi, amap, NULL); 1281 1282 counters_inc(uvmexp_counters, flt_get); 1283 gotpages = 1; 1284 uoff = (ufi->orig_rvaddr - ufi->entry->start) + ufi->entry->offset; 1285 result = uobj->pgops->pgo_get(uobj, uoff, &uobjpage, &gotpages, 1286 0, flt->access_type & MASK(ufi->entry), ufi->entry->advice, 1287 PGO_SYNCIO); 1288 1289 /* 1290 * recover from I/O 1291 */ 1292 if (result != VM_PAGER_OK) { 1293 KASSERT(result != VM_PAGER_PEND); 1294 1295 if (result == VM_PAGER_AGAIN) { 1296 tsleep_nsec(&nowake, PVM, "fltagain2", 1297 MSEC_TO_NSEC(5)); 1298 return ERESTART; 1299 } 1300 1301 if (!UVM_ET_ISNOFAULT(ufi->entry)) 1302 return (EIO); 1303 1304 uobjpage = PGO_DONTCARE; 1305 uobj = NULL; 1306 promote = TRUE; 1307 } 1308 1309 /* re-verify the state of the world. */ 1310 locked = uvmfault_relock(ufi); 1311 if (locked && amap != NULL) 1312 amap_lock(amap); 1313 1314 /* might be changed */ 1315 if (uobjpage != PGO_DONTCARE) { 1316 uobj = uobjpage->uobject; 1317 rw_enter(uobj->vmobjlock, RW_WRITE); 1318 } 1319 1320 /* 1321 * Re-verify that amap slot is still free. if there is 1322 * a problem, we clean up. 1323 */ 1324 if (locked && amap && amap_lookup(&ufi->entry->aref, 1325 ufi->orig_rvaddr - ufi->entry->start)) { 1326 if (locked) 1327 uvmfault_unlockall(ufi, amap, NULL); 1328 locked = FALSE; 1329 } 1330 1331 /* didn't get the lock? release the page and retry. */ 1332 if (locked == FALSE && uobjpage != PGO_DONTCARE) { 1333 uvm_lock_pageq(); 1334 /* make sure it is in queues */ 1335 uvm_pageactivate(uobjpage); 1336 uvm_unlock_pageq(); 1337 1338 if (uobjpage->pg_flags & PG_WANTED) 1339 /* still holding object lock */ 1340 wakeup(uobjpage); 1341 atomic_clearbits_int(&uobjpage->pg_flags, 1342 PG_BUSY|PG_WANTED); 1343 UVM_PAGE_OWN(uobjpage, NULL); 1344 } 1345 1346 if (locked == FALSE) { 1347 if (uobjpage != PGO_DONTCARE) 1348 rw_exit(uobj->vmobjlock); 1349 return ERESTART; 1350 } 1351 1352 /* 1353 * we have the data in uobjpage which is PG_BUSY 1354 */ 1355 } 1356 1357 /* 1358 * notes: 1359 * - at this point uobjpage can not be NULL 1360 * - at this point uobjpage could be PG_WANTED (handle later) 1361 */ 1362 if (promote == FALSE) { 1363 /* 1364 * we are not promoting. if the mapping is COW ensure that we 1365 * don't give more access than we should (e.g. when doing a read 1366 * fault on a COPYONWRITE mapping we want to map the COW page in 1367 * R/O even though the entry protection could be R/W). 1368 * 1369 * set "pg" to the page we want to map in (uobjpage, usually) 1370 */ 1371 counters_inc(uvmexp_counters, flt_obj); 1372 if (UVM_ET_ISCOPYONWRITE(ufi->entry)) 1373 flt->enter_prot &= ~PROT_WRITE; 1374 pg = uobjpage; /* map in the actual object */ 1375 1376 /* assert(uobjpage != PGO_DONTCARE) */ 1377 1378 /* 1379 * we are faulting directly on the page. 1380 */ 1381 } else { 1382 /* 1383 * if we are going to promote the data to an anon we 1384 * allocate a blank anon here and plug it into our amap. 1385 */ 1386 #ifdef DIAGNOSTIC 1387 if (amap == NULL) 1388 panic("uvm_fault: want to promote data, but no anon"); 1389 #endif 1390 1391 anon = uvm_analloc(); 1392 if (anon) { 1393 /* 1394 * In `Fill in data...' below, if 1395 * uobjpage == PGO_DONTCARE, we want 1396 * a zero'd, dirty page, so have 1397 * uvm_pagealloc() do that for us. 1398 */ 1399 anon->an_lock = amap->am_lock; 1400 pg = uvm_pagealloc(NULL, 0, anon, 1401 (uobjpage == PGO_DONTCARE) ? UVM_PGA_ZERO : 0); 1402 } 1403 1404 /* 1405 * out of memory resources? 1406 */ 1407 if (anon == NULL || pg == NULL) { 1408 /* 1409 * arg! must unbusy our page and fail or sleep. 1410 */ 1411 if (uobjpage != PGO_DONTCARE) { 1412 uvm_lock_pageq(); 1413 uvm_pageactivate(uobjpage); 1414 uvm_unlock_pageq(); 1415 1416 if (uobjpage->pg_flags & PG_WANTED) 1417 wakeup(uobjpage); 1418 atomic_clearbits_int(&uobjpage->pg_flags, 1419 PG_BUSY|PG_WANTED); 1420 UVM_PAGE_OWN(uobjpage, NULL); 1421 } 1422 1423 /* unlock and fail ... */ 1424 uvmfault_unlockall(ufi, amap, uobj); 1425 if (anon == NULL) 1426 counters_inc(uvmexp_counters, flt_noanon); 1427 else { 1428 anon->an_lock = NULL; 1429 anon->an_ref--; 1430 uvm_anfree(anon); 1431 counters_inc(uvmexp_counters, flt_noram); 1432 } 1433 1434 if (uvm_swapisfull()) 1435 return (ENOMEM); 1436 1437 /* out of RAM, wait for more */ 1438 if (anon == NULL) 1439 uvm_anwait(); 1440 else 1441 uvm_wait("flt_noram5"); 1442 return ERESTART; 1443 } 1444 1445 /* 1446 * fill in the data 1447 */ 1448 if (uobjpage != PGO_DONTCARE) { 1449 counters_inc(uvmexp_counters, flt_prcopy); 1450 /* copy page [pg now dirty] */ 1451 uvm_pagecopy(uobjpage, pg); 1452 1453 /* 1454 * promote to shared amap? make sure all sharing 1455 * procs see it 1456 */ 1457 if ((amap_flags(amap) & AMAP_SHARED) != 0) { 1458 pmap_page_protect(uobjpage, PROT_NONE); 1459 } 1460 1461 /* dispose of uobjpage. drop handle to uobj as well. */ 1462 if (uobjpage->pg_flags & PG_WANTED) 1463 wakeup(uobjpage); 1464 atomic_clearbits_int(&uobjpage->pg_flags, 1465 PG_BUSY|PG_WANTED); 1466 UVM_PAGE_OWN(uobjpage, NULL); 1467 uvm_lock_pageq(); 1468 uvm_pageactivate(uobjpage); 1469 uvm_unlock_pageq(); 1470 rw_exit(uobj->vmobjlock); 1471 uobj = NULL; 1472 } else { 1473 counters_inc(uvmexp_counters, flt_przero); 1474 /* 1475 * Page is zero'd and marked dirty by uvm_pagealloc() 1476 * above. 1477 */ 1478 } 1479 1480 if (amap_add(&ufi->entry->aref, 1481 ufi->orig_rvaddr - ufi->entry->start, anon, 0)) { 1482 uvmfault_unlockall(ufi, amap, uobj); 1483 uvm_anfree(anon); 1484 counters_inc(uvmexp_counters, flt_noamap); 1485 1486 if (uvm_swapisfull()) 1487 return (ENOMEM); 1488 1489 amap_populate(&ufi->entry->aref, 1490 ufi->orig_rvaddr - ufi->entry->start); 1491 return ERESTART; 1492 } 1493 } 1494 1495 /* note: pg is either the uobjpage or the new page in the new anon */ 1496 /* 1497 * all resources are present. we can now map it in and free our 1498 * resources. 1499 */ 1500 if (amap == NULL) 1501 KASSERT(anon == NULL); 1502 else { 1503 KASSERT(rw_write_held(amap->am_lock)); 1504 KASSERT(anon == NULL || anon->an_lock == amap->am_lock); 1505 } 1506 if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr, 1507 VM_PAGE_TO_PHYS(pg) | flt->pa_flags, flt->enter_prot, 1508 flt->access_type | PMAP_CANFAIL | (flt->wired ? PMAP_WIRED : 0)) != 0) { 1509 /* 1510 * No need to undo what we did; we can simply think of 1511 * this as the pmap throwing away the mapping information. 1512 * 1513 * We do, however, have to go through the ReFault path, 1514 * as the map may change while we're asleep. 1515 */ 1516 if (pg->pg_flags & PG_WANTED) 1517 wakeup(pg); 1518 1519 atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_FAKE|PG_WANTED); 1520 UVM_PAGE_OWN(pg, NULL); 1521 uvmfault_unlockall(ufi, amap, uobj); 1522 if (uvm_swapisfull()) { 1523 /* XXX instrumentation */ 1524 return (ENOMEM); 1525 } 1526 /* XXX instrumentation */ 1527 uvm_wait("flt_pmfail2"); 1528 return ERESTART; 1529 } 1530 1531 if (fault_type == VM_FAULT_WIRE) { 1532 uvm_lock_pageq(); 1533 uvm_pagewire(pg); 1534 uvm_unlock_pageq(); 1535 if (pg->pg_flags & PQ_AOBJ) { 1536 /* 1537 * since the now-wired page cannot be paged out, 1538 * release its swap resources for others to use. 1539 * since an aobj page with no swap cannot be clean, 1540 * mark it dirty now. 1541 * 1542 * use pg->uobject here. if the page is from a 1543 * tmpfs vnode, the pages are backed by its UAO and 1544 * not the vnode. 1545 */ 1546 KASSERT(uobj != NULL); 1547 KASSERT(uobj->vmobjlock == pg->uobject->vmobjlock); 1548 atomic_clearbits_int(&pg->pg_flags, PG_CLEAN); 1549 uao_dropswap(uobj, pg->offset >> PAGE_SHIFT); 1550 } 1551 } else { 1552 /* activate it */ 1553 uvm_lock_pageq(); 1554 uvm_pageactivate(pg); 1555 uvm_unlock_pageq(); 1556 } 1557 1558 if (pg->pg_flags & PG_WANTED) 1559 wakeup(pg); 1560 1561 atomic_clearbits_int(&pg->pg_flags, PG_BUSY|PG_FAKE|PG_WANTED); 1562 UVM_PAGE_OWN(pg, NULL); 1563 uvmfault_unlockall(ufi, amap, uobj); 1564 pmap_update(ufi->orig_map->pmap); 1565 1566 return (0); 1567 } 1568 1569 1570 /* 1571 * uvm_fault_wire: wire down a range of virtual addresses in a map. 1572 * 1573 * => map may be read-locked by caller, but MUST NOT be write-locked. 1574 * => if map is read-locked, any operations which may cause map to 1575 * be write-locked in uvm_fault() must be taken care of by 1576 * the caller. See uvm_map_pageable(). 1577 */ 1578 int 1579 uvm_fault_wire(vm_map_t map, vaddr_t start, vaddr_t end, vm_prot_t access_type) 1580 { 1581 vaddr_t va; 1582 int rv; 1583 1584 /* 1585 * now fault it in a page at a time. if the fault fails then we have 1586 * to undo what we have done. note that in uvm_fault PROT_NONE 1587 * is replaced with the max protection if fault_type is VM_FAULT_WIRE. 1588 */ 1589 for (va = start ; va < end ; va += PAGE_SIZE) { 1590 rv = uvm_fault(map, va, VM_FAULT_WIRE, access_type); 1591 if (rv) { 1592 if (va != start) { 1593 uvm_fault_unwire(map, start, va); 1594 } 1595 return (rv); 1596 } 1597 } 1598 1599 return (0); 1600 } 1601 1602 /* 1603 * uvm_fault_unwire(): unwire range of virtual space. 1604 */ 1605 void 1606 uvm_fault_unwire(vm_map_t map, vaddr_t start, vaddr_t end) 1607 { 1608 1609 vm_map_lock_read(map); 1610 uvm_fault_unwire_locked(map, start, end); 1611 vm_map_unlock_read(map); 1612 } 1613 1614 /* 1615 * uvm_fault_unwire_locked(): the guts of uvm_fault_unwire(). 1616 * 1617 * => map must be at least read-locked. 1618 */ 1619 void 1620 uvm_fault_unwire_locked(vm_map_t map, vaddr_t start, vaddr_t end) 1621 { 1622 vm_map_entry_t entry, oentry = NULL, next; 1623 pmap_t pmap = vm_map_pmap(map); 1624 vaddr_t va; 1625 paddr_t pa; 1626 struct vm_page *pg; 1627 1628 KASSERT((map->flags & VM_MAP_INTRSAFE) == 0); 1629 vm_map_assert_anylock(map); 1630 1631 /* 1632 * we assume that the area we are unwiring has actually been wired 1633 * in the first place. this means that we should be able to extract 1634 * the PAs from the pmap. 1635 */ 1636 1637 /* 1638 * find the beginning map entry for the region. 1639 */ 1640 KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map)); 1641 if (uvm_map_lookup_entry(map, start, &entry) == FALSE) 1642 panic("uvm_fault_unwire_locked: address not in map"); 1643 1644 for (va = start; va < end ; va += PAGE_SIZE) { 1645 if (pmap_extract(pmap, va, &pa) == FALSE) 1646 continue; 1647 1648 /* 1649 * find the map entry for the current address. 1650 */ 1651 KASSERT(va >= entry->start); 1652 while (entry && va >= entry->end) { 1653 next = RBT_NEXT(uvm_map_addr, entry); 1654 entry = next; 1655 } 1656 1657 if (entry == NULL) 1658 return; 1659 if (va < entry->start) 1660 continue; 1661 1662 /* 1663 * lock it. 1664 */ 1665 if (entry != oentry) { 1666 if (oentry != NULL) { 1667 uvm_map_unlock_entry(oentry); 1668 } 1669 uvm_map_lock_entry(entry); 1670 oentry = entry; 1671 } 1672 1673 /* 1674 * if the entry is no longer wired, tell the pmap. 1675 */ 1676 if (VM_MAPENT_ISWIRED(entry) == 0) 1677 pmap_unwire(pmap, va); 1678 1679 pg = PHYS_TO_VM_PAGE(pa); 1680 if (pg) { 1681 uvm_lock_pageq(); 1682 uvm_pageunwire(pg); 1683 uvm_unlock_pageq(); 1684 } 1685 } 1686 1687 if (oentry != NULL) { 1688 uvm_map_unlock_entry(oentry); 1689 } 1690 } 1691 1692 /* 1693 * uvmfault_unlockmaps: unlock the maps 1694 */ 1695 void 1696 uvmfault_unlockmaps(struct uvm_faultinfo *ufi, boolean_t write_locked) 1697 { 1698 /* 1699 * ufi can be NULL when this isn't really a fault, 1700 * but merely paging in anon data. 1701 */ 1702 if (ufi == NULL) { 1703 return; 1704 } 1705 1706 uvmfault_update_stats(ufi); 1707 if (write_locked) { 1708 vm_map_unlock(ufi->map); 1709 } else { 1710 vm_map_unlock_read(ufi->map); 1711 } 1712 } 1713 1714 /* 1715 * uvmfault_unlockall: unlock everything passed in. 1716 * 1717 * => maps must be read-locked (not write-locked). 1718 */ 1719 void 1720 uvmfault_unlockall(struct uvm_faultinfo *ufi, struct vm_amap *amap, 1721 struct uvm_object *uobj) 1722 { 1723 if (uobj) 1724 rw_exit(uobj->vmobjlock); 1725 if (amap != NULL) 1726 amap_unlock(amap); 1727 uvmfault_unlockmaps(ufi, FALSE); 1728 } 1729 1730 /* 1731 * uvmfault_lookup: lookup a virtual address in a map 1732 * 1733 * => caller must provide a uvm_faultinfo structure with the IN 1734 * params properly filled in 1735 * => we will lookup the map entry (handling submaps) as we go 1736 * => if the lookup is a success we will return with the maps locked 1737 * => if "write_lock" is TRUE, we write_lock the map, otherwise we only 1738 * get a read lock. 1739 * => note that submaps can only appear in the kernel and they are 1740 * required to use the same virtual addresses as the map they 1741 * are referenced by (thus address translation between the main 1742 * map and the submap is unnecessary). 1743 */ 1744 1745 boolean_t 1746 uvmfault_lookup(struct uvm_faultinfo *ufi, boolean_t write_lock) 1747 { 1748 vm_map_t tmpmap; 1749 1750 /* 1751 * init ufi values for lookup. 1752 */ 1753 ufi->map = ufi->orig_map; 1754 ufi->size = ufi->orig_size; 1755 1756 /* 1757 * keep going down levels until we are done. note that there can 1758 * only be two levels so we won't loop very long. 1759 */ 1760 while (1) { 1761 if (ufi->orig_rvaddr < ufi->map->min_offset || 1762 ufi->orig_rvaddr >= ufi->map->max_offset) 1763 return FALSE; 1764 1765 /* lock map */ 1766 if (write_lock) { 1767 vm_map_lock(ufi->map); 1768 } else { 1769 vm_map_lock_read(ufi->map); 1770 } 1771 1772 /* lookup */ 1773 if (!uvm_map_lookup_entry(ufi->map, ufi->orig_rvaddr, 1774 &ufi->entry)) { 1775 uvmfault_unlockmaps(ufi, write_lock); 1776 return FALSE; 1777 } 1778 1779 /* reduce size if necessary */ 1780 if (ufi->entry->end - ufi->orig_rvaddr < ufi->size) 1781 ufi->size = ufi->entry->end - ufi->orig_rvaddr; 1782 1783 /* 1784 * submap? replace map with the submap and lookup again. 1785 * note: VAs in submaps must match VAs in main map. 1786 */ 1787 if (UVM_ET_ISSUBMAP(ufi->entry)) { 1788 tmpmap = ufi->entry->object.sub_map; 1789 uvmfault_unlockmaps(ufi, write_lock); 1790 ufi->map = tmpmap; 1791 continue; 1792 } 1793 1794 /* 1795 * got it! 1796 */ 1797 ufi->mapv = ufi->map->timestamp; 1798 return TRUE; 1799 1800 } /* while loop */ 1801 1802 /*NOTREACHED*/ 1803 } 1804 1805 /* 1806 * uvmfault_relock: attempt to relock the same version of the map 1807 * 1808 * => fault data structures should be unlocked before calling. 1809 * => if a success (TRUE) maps will be locked after call. 1810 */ 1811 boolean_t 1812 uvmfault_relock(struct uvm_faultinfo *ufi) 1813 { 1814 /* 1815 * ufi can be NULL when this isn't really a fault, 1816 * but merely paging in anon data. 1817 */ 1818 if (ufi == NULL) { 1819 return TRUE; 1820 } 1821 1822 counters_inc(uvmexp_counters, flt_relck); 1823 1824 /* 1825 * relock map. fail if version mismatch (in which case nothing 1826 * gets locked). 1827 */ 1828 vm_map_lock_read(ufi->map); 1829 if (ufi->mapv != ufi->map->timestamp) { 1830 vm_map_unlock_read(ufi->map); 1831 return FALSE; 1832 } 1833 1834 counters_inc(uvmexp_counters, flt_relckok); 1835 return TRUE; /* got it! */ 1836 }
Cache object: 8eb1f9b7a8e91b6a336d2d135003fbd8
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