| 1 | /* $NetBSD: uvm_fault.c,v 1.197 2015/06/22 06:24:17 matt Exp $ */ |
| 2 | |
| 3 | /* |
| 4 | * Copyright (c) 1997 Charles D. Cranor and Washington University. |
| 5 | * All rights reserved. |
| 6 | * |
| 7 | * Redistribution and use in source and binary forms, with or without |
| 8 | * modification, are permitted provided that the following conditions |
| 9 | * are met: |
| 10 | * 1. Redistributions of source code must retain the above copyright |
| 11 | * notice, this list of conditions and the following disclaimer. |
| 12 | * 2. Redistributions in binary form must reproduce the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer in the |
| 14 | * documentation and/or other materials provided with the distribution. |
| 15 | * |
| 16 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
| 17 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| 18 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
| 19 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
| 20 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
| 21 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 22 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 23 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 24 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
| 25 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 26 | * |
| 27 | * from: Id: uvm_fault.c,v 1.1.2.23 1998/02/06 05:29:05 chs Exp |
| 28 | */ |
| 29 | |
| 30 | /* |
| 31 | * uvm_fault.c: fault handler |
| 32 | */ |
| 33 | |
| 34 | #include <sys/cdefs.h> |
| 35 | __KERNEL_RCSID(0, "$NetBSD: uvm_fault.c,v 1.197 2015/06/22 06:24:17 matt Exp $" ); |
| 36 | |
| 37 | #include "opt_uvmhist.h" |
| 38 | |
| 39 | #include <sys/param.h> |
| 40 | #include <sys/systm.h> |
| 41 | #include <sys/kernel.h> |
| 42 | #include <sys/mman.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_internal) |
| 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 | |
| 147 | struct uvm_advice { |
| 148 | int advice; |
| 149 | int nback; |
| 150 | int nforw; |
| 151 | }; |
| 152 | |
| 153 | /* |
| 154 | * page range array: |
| 155 | * note: index in array must match "advice" value |
| 156 | * XXX: borrowed numbers from freebsd. do they work well for us? |
| 157 | */ |
| 158 | |
| 159 | static const struct uvm_advice uvmadvice[] = { |
| 160 | { UVM_ADV_NORMAL, 3, 4 }, |
| 161 | { UVM_ADV_RANDOM, 0, 0 }, |
| 162 | { UVM_ADV_SEQUENTIAL, 8, 7}, |
| 163 | }; |
| 164 | |
| 165 | #define UVM_MAXRANGE 16 /* must be MAX() of nback+nforw+1 */ |
| 166 | |
| 167 | /* |
| 168 | * private prototypes |
| 169 | */ |
| 170 | |
| 171 | /* |
| 172 | * externs from other modules |
| 173 | */ |
| 174 | |
| 175 | extern int start_init_exec; /* Is init_main() done / init running? */ |
| 176 | |
| 177 | /* |
| 178 | * inline functions |
| 179 | */ |
| 180 | |
| 181 | /* |
| 182 | * uvmfault_anonflush: try and deactivate pages in specified anons |
| 183 | * |
| 184 | * => does not have to deactivate page if it is busy |
| 185 | */ |
| 186 | |
| 187 | static inline void |
| 188 | uvmfault_anonflush(struct vm_anon **anons, int n) |
| 189 | { |
| 190 | int lcv; |
| 191 | struct vm_page *pg; |
| 192 | |
| 193 | for (lcv = 0; lcv < n; lcv++) { |
| 194 | if (anons[lcv] == NULL) |
| 195 | continue; |
| 196 | KASSERT(mutex_owned(anons[lcv]->an_lock)); |
| 197 | pg = anons[lcv]->an_page; |
| 198 | if (pg && (pg->flags & PG_BUSY) == 0) { |
| 199 | mutex_enter(&uvm_pageqlock); |
| 200 | if (pg->wire_count == 0) { |
| 201 | uvm_pagedeactivate(pg); |
| 202 | } |
| 203 | mutex_exit(&uvm_pageqlock); |
| 204 | } |
| 205 | } |
| 206 | } |
| 207 | |
| 208 | /* |
| 209 | * normal functions |
| 210 | */ |
| 211 | |
| 212 | /* |
| 213 | * uvmfault_amapcopy: clear "needs_copy" in a map. |
| 214 | * |
| 215 | * => called with VM data structures unlocked (usually, see below) |
| 216 | * => we get a write lock on the maps and clear needs_copy for a VA |
| 217 | * => if we are out of RAM we sleep (waiting for more) |
| 218 | */ |
| 219 | |
| 220 | static void |
| 221 | uvmfault_amapcopy(struct uvm_faultinfo *ufi) |
| 222 | { |
| 223 | for (;;) { |
| 224 | |
| 225 | /* |
| 226 | * no mapping? give up. |
| 227 | */ |
| 228 | |
| 229 | if (uvmfault_lookup(ufi, true) == false) |
| 230 | return; |
| 231 | |
| 232 | /* |
| 233 | * copy if needed. |
| 234 | */ |
| 235 | |
| 236 | if (UVM_ET_ISNEEDSCOPY(ufi->entry)) |
| 237 | amap_copy(ufi->map, ufi->entry, AMAP_COPY_NOWAIT, |
| 238 | ufi->orig_rvaddr, ufi->orig_rvaddr + 1); |
| 239 | |
| 240 | /* |
| 241 | * didn't work? must be out of RAM. unlock and sleep. |
| 242 | */ |
| 243 | |
| 244 | if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { |
| 245 | uvmfault_unlockmaps(ufi, true); |
| 246 | uvm_wait("fltamapcopy" ); |
| 247 | continue; |
| 248 | } |
| 249 | |
| 250 | /* |
| 251 | * got it! unlock and return. |
| 252 | */ |
| 253 | |
| 254 | uvmfault_unlockmaps(ufi, true); |
| 255 | return; |
| 256 | } |
| 257 | /*NOTREACHED*/ |
| 258 | } |
| 259 | |
| 260 | /* |
| 261 | * uvmfault_anonget: get data in an anon into a non-busy, non-released |
| 262 | * page in that anon. |
| 263 | * |
| 264 | * => Map, amap and thus anon should be locked by caller. |
| 265 | * => If we fail, we unlock everything and error is returned. |
| 266 | * => If we are successful, return with everything still locked. |
| 267 | * => We do not move the page on the queues [gets moved later]. If we |
| 268 | * allocate a new page [we_own], it gets put on the queues. Either way, |
| 269 | * the result is that the page is on the queues at return time |
| 270 | * => For pages which are on loan from a uvm_object (and thus are not owned |
| 271 | * by the anon): if successful, return with the owning object locked. |
| 272 | * The caller must unlock this object when it unlocks everything else. |
| 273 | */ |
| 274 | |
| 275 | int |
| 276 | uvmfault_anonget(struct uvm_faultinfo *ufi, struct vm_amap *amap, |
| 277 | struct vm_anon *anon) |
| 278 | { |
| 279 | struct vm_page *pg; |
| 280 | int error; |
| 281 | |
| 282 | UVMHIST_FUNC("uvmfault_anonget" ); UVMHIST_CALLED(maphist); |
| 283 | KASSERT(mutex_owned(anon->an_lock)); |
| 284 | KASSERT(anon->an_lock == amap->am_lock); |
| 285 | |
| 286 | /* Increment the counters.*/ |
| 287 | uvmexp.fltanget++; |
| 288 | if (anon->an_page) { |
| 289 | curlwp->l_ru.ru_minflt++; |
| 290 | } else { |
| 291 | curlwp->l_ru.ru_majflt++; |
| 292 | } |
| 293 | error = 0; |
| 294 | |
| 295 | /* |
| 296 | * Loop until we get the anon data, or fail. |
| 297 | */ |
| 298 | |
| 299 | for (;;) { |
| 300 | bool we_own, locked; |
| 301 | /* |
| 302 | * Note: 'we_own' will become true if we set PG_BUSY on a page. |
| 303 | */ |
| 304 | we_own = false; |
| 305 | pg = anon->an_page; |
| 306 | |
| 307 | /* |
| 308 | * If there is a resident page and it is loaned, then anon |
| 309 | * may not own it. Call out to uvm_anon_lockloanpg() to |
| 310 | * identify and lock the real owner of the page. |
| 311 | */ |
| 312 | |
| 313 | if (pg && pg->loan_count) |
| 314 | pg = uvm_anon_lockloanpg(anon); |
| 315 | |
| 316 | /* |
| 317 | * Is page resident? Make sure it is not busy/released. |
| 318 | */ |
| 319 | |
| 320 | if (pg) { |
| 321 | |
| 322 | /* |
| 323 | * at this point, if the page has a uobject [meaning |
| 324 | * we have it on loan], then that uobject is locked |
| 325 | * by us! if the page is busy, we drop all the |
| 326 | * locks (including uobject) and try again. |
| 327 | */ |
| 328 | |
| 329 | if ((pg->flags & PG_BUSY) == 0) { |
| 330 | UVMHIST_LOG(maphist, "<- OK" ,0,0,0,0); |
| 331 | return 0; |
| 332 | } |
| 333 | pg->flags |= PG_WANTED; |
| 334 | uvmexp.fltpgwait++; |
| 335 | |
| 336 | /* |
| 337 | * The last unlock must be an atomic unlock and wait |
| 338 | * on the owner of page. |
| 339 | */ |
| 340 | |
| 341 | if (pg->uobject) { |
| 342 | /* Owner of page is UVM object. */ |
| 343 | uvmfault_unlockall(ufi, amap, NULL); |
| 344 | UVMHIST_LOG(maphist, " unlock+wait on uobj" ,0, |
| 345 | 0,0,0); |
| 346 | UVM_UNLOCK_AND_WAIT(pg, |
| 347 | pg->uobject->vmobjlock, |
| 348 | false, "anonget1" , 0); |
| 349 | } else { |
| 350 | /* Owner of page is anon. */ |
| 351 | uvmfault_unlockall(ufi, NULL, NULL); |
| 352 | UVMHIST_LOG(maphist, " unlock+wait on anon" ,0, |
| 353 | 0,0,0); |
| 354 | UVM_UNLOCK_AND_WAIT(pg, anon->an_lock, |
| 355 | false, "anonget2" , 0); |
| 356 | } |
| 357 | } else { |
| 358 | #if defined(VMSWAP) |
| 359 | /* |
| 360 | * No page, therefore allocate one. |
| 361 | */ |
| 362 | |
| 363 | pg = uvm_pagealloc(NULL, |
| 364 | ufi != NULL ? ufi->orig_rvaddr : 0, |
| 365 | anon, ufi != NULL ? UVM_FLAG_COLORMATCH : 0); |
| 366 | if (pg == NULL) { |
| 367 | /* Out of memory. Wait a little. */ |
| 368 | uvmfault_unlockall(ufi, amap, NULL); |
| 369 | uvmexp.fltnoram++; |
| 370 | UVMHIST_LOG(maphist, " noram -- UVM_WAIT" ,0, |
| 371 | 0,0,0); |
| 372 | if (!uvm_reclaimable()) { |
| 373 | return ENOMEM; |
| 374 | } |
| 375 | uvm_wait("flt_noram1" ); |
| 376 | } else { |
| 377 | /* PG_BUSY bit is set. */ |
| 378 | we_own = true; |
| 379 | uvmfault_unlockall(ufi, amap, NULL); |
| 380 | |
| 381 | /* |
| 382 | * Pass a PG_BUSY+PG_FAKE+PG_CLEAN page into |
| 383 | * the uvm_swap_get() function with all data |
| 384 | * structures unlocked. Note that it is OK |
| 385 | * to read an_swslot here, because we hold |
| 386 | * PG_BUSY on the page. |
| 387 | */ |
| 388 | uvmexp.pageins++; |
| 389 | error = uvm_swap_get(pg, anon->an_swslot, |
| 390 | PGO_SYNCIO); |
| 391 | |
| 392 | /* |
| 393 | * We clean up after the I/O below in the |
| 394 | * 'we_own' case. |
| 395 | */ |
| 396 | } |
| 397 | #else |
| 398 | panic("%s: no page" , __func__); |
| 399 | #endif /* defined(VMSWAP) */ |
| 400 | } |
| 401 | |
| 402 | /* |
| 403 | * Re-lock the map and anon. |
| 404 | */ |
| 405 | |
| 406 | locked = uvmfault_relock(ufi); |
| 407 | if (locked || we_own) { |
| 408 | mutex_enter(anon->an_lock); |
| 409 | } |
| 410 | |
| 411 | /* |
| 412 | * If we own the page (i.e. we set PG_BUSY), then we need |
| 413 | * to clean up after the I/O. There are three cases to |
| 414 | * consider: |
| 415 | * |
| 416 | * 1) Page was released during I/O: free anon and ReFault. |
| 417 | * 2) I/O not OK. Free the page and cause the fault to fail. |
| 418 | * 3) I/O OK! Activate the page and sync with the non-we_own |
| 419 | * case (i.e. drop anon lock if not locked). |
| 420 | */ |
| 421 | |
| 422 | if (we_own) { |
| 423 | #if defined(VMSWAP) |
| 424 | if (pg->flags & PG_WANTED) { |
| 425 | wakeup(pg); |
| 426 | } |
| 427 | if (error) { |
| 428 | |
| 429 | /* |
| 430 | * Remove the swap slot from the anon and |
| 431 | * mark the anon as having no real slot. |
| 432 | * Do not free the swap slot, thus preventing |
| 433 | * it from being used again. |
| 434 | */ |
| 435 | |
| 436 | if (anon->an_swslot > 0) { |
| 437 | uvm_swap_markbad(anon->an_swslot, 1); |
| 438 | } |
| 439 | anon->an_swslot = SWSLOT_BAD; |
| 440 | |
| 441 | if ((pg->flags & PG_RELEASED) != 0) { |
| 442 | goto released; |
| 443 | } |
| 444 | |
| 445 | /* |
| 446 | * Note: page was never !PG_BUSY, so it |
| 447 | * cannot be mapped and thus no need to |
| 448 | * pmap_page_protect() it. |
| 449 | */ |
| 450 | |
| 451 | mutex_enter(&uvm_pageqlock); |
| 452 | uvm_pagefree(pg); |
| 453 | mutex_exit(&uvm_pageqlock); |
| 454 | |
| 455 | if (locked) { |
| 456 | uvmfault_unlockall(ufi, NULL, NULL); |
| 457 | } |
| 458 | mutex_exit(anon->an_lock); |
| 459 | UVMHIST_LOG(maphist, "<- ERROR" , 0,0,0,0); |
| 460 | return error; |
| 461 | } |
| 462 | |
| 463 | if ((pg->flags & PG_RELEASED) != 0) { |
| 464 | released: |
| 465 | KASSERT(anon->an_ref == 0); |
| 466 | |
| 467 | /* |
| 468 | * Released while we had unlocked amap. |
| 469 | */ |
| 470 | |
| 471 | if (locked) { |
| 472 | uvmfault_unlockall(ufi, NULL, NULL); |
| 473 | } |
| 474 | uvm_anon_release(anon); |
| 475 | |
| 476 | if (error) { |
| 477 | UVMHIST_LOG(maphist, |
| 478 | "<- ERROR/RELEASED" , 0,0,0,0); |
| 479 | return error; |
| 480 | } |
| 481 | |
| 482 | UVMHIST_LOG(maphist, "<- RELEASED" , 0,0,0,0); |
| 483 | return ERESTART; |
| 484 | } |
| 485 | |
| 486 | /* |
| 487 | * We have successfully read the page, activate it. |
| 488 | */ |
| 489 | |
| 490 | mutex_enter(&uvm_pageqlock); |
| 491 | uvm_pageactivate(pg); |
| 492 | mutex_exit(&uvm_pageqlock); |
| 493 | pg->flags &= ~(PG_WANTED|PG_BUSY|PG_FAKE); |
| 494 | UVM_PAGE_OWN(pg, NULL); |
| 495 | #else |
| 496 | panic("%s: we_own" , __func__); |
| 497 | #endif /* defined(VMSWAP) */ |
| 498 | } |
| 499 | |
| 500 | /* |
| 501 | * We were not able to re-lock the map - restart the fault. |
| 502 | */ |
| 503 | |
| 504 | if (!locked) { |
| 505 | if (we_own) { |
| 506 | mutex_exit(anon->an_lock); |
| 507 | } |
| 508 | UVMHIST_LOG(maphist, "<- REFAULT" , 0,0,0,0); |
| 509 | return ERESTART; |
| 510 | } |
| 511 | |
| 512 | /* |
| 513 | * Verify that no one has touched the amap and moved |
| 514 | * the anon on us. |
| 515 | */ |
| 516 | |
| 517 | if (ufi != NULL && amap_lookup(&ufi->entry->aref, |
| 518 | ufi->orig_rvaddr - ufi->entry->start) != anon) { |
| 519 | |
| 520 | uvmfault_unlockall(ufi, amap, NULL); |
| 521 | UVMHIST_LOG(maphist, "<- REFAULT" , 0,0,0,0); |
| 522 | return ERESTART; |
| 523 | } |
| 524 | |
| 525 | /* |
| 526 | * Retry.. |
| 527 | */ |
| 528 | |
| 529 | uvmexp.fltanretry++; |
| 530 | continue; |
| 531 | } |
| 532 | /*NOTREACHED*/ |
| 533 | } |
| 534 | |
| 535 | /* |
| 536 | * uvmfault_promote: promote data to a new anon. used for 1B and 2B. |
| 537 | * |
| 538 | * 1. allocate an anon and a page. |
| 539 | * 2. fill its contents. |
| 540 | * 3. put it into amap. |
| 541 | * |
| 542 | * => if we fail (result != 0) we unlock everything. |
| 543 | * => on success, return a new locked anon via 'nanon'. |
| 544 | * (*nanon)->an_page will be a resident, locked, dirty page. |
| 545 | * => it's caller's responsibility to put the promoted nanon->an_page to the |
| 546 | * page queue. |
| 547 | */ |
| 548 | |
| 549 | static int |
| 550 | uvmfault_promote(struct uvm_faultinfo *ufi, |
| 551 | struct vm_anon *oanon, |
| 552 | struct vm_page *uobjpage, |
| 553 | struct vm_anon **nanon, /* OUT: allocated anon */ |
| 554 | struct vm_anon **spare) |
| 555 | { |
| 556 | struct vm_amap *amap = ufi->entry->aref.ar_amap; |
| 557 | struct uvm_object *uobj; |
| 558 | struct vm_anon *anon; |
| 559 | struct vm_page *pg; |
| 560 | struct vm_page *opg; |
| 561 | int error; |
| 562 | UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); |
| 563 | |
| 564 | if (oanon) { |
| 565 | /* anon COW */ |
| 566 | opg = oanon->an_page; |
| 567 | KASSERT(opg != NULL); |
| 568 | KASSERT(opg->uobject == NULL || opg->loan_count > 0); |
| 569 | } else if (uobjpage != PGO_DONTCARE) { |
| 570 | /* object-backed COW */ |
| 571 | opg = uobjpage; |
| 572 | } else { |
| 573 | /* ZFOD */ |
| 574 | opg = NULL; |
| 575 | } |
| 576 | if (opg != NULL) { |
| 577 | uobj = opg->uobject; |
| 578 | } else { |
| 579 | uobj = NULL; |
| 580 | } |
| 581 | |
| 582 | KASSERT(amap != NULL); |
| 583 | KASSERT(uobjpage != NULL); |
| 584 | KASSERT(uobjpage == PGO_DONTCARE || (uobjpage->flags & PG_BUSY) != 0); |
| 585 | KASSERT(mutex_owned(amap->am_lock)); |
| 586 | KASSERT(oanon == NULL || amap->am_lock == oanon->an_lock); |
| 587 | KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); |
| 588 | |
| 589 | if (*spare != NULL) { |
| 590 | anon = *spare; |
| 591 | *spare = NULL; |
| 592 | } else { |
| 593 | anon = uvm_analloc(); |
| 594 | } |
| 595 | if (anon) { |
| 596 | |
| 597 | /* |
| 598 | * The new anon is locked. |
| 599 | * |
| 600 | * if opg == NULL, we want a zero'd, dirty page, |
| 601 | * so have uvm_pagealloc() do that for us. |
| 602 | */ |
| 603 | |
| 604 | KASSERT(anon->an_lock == NULL); |
| 605 | anon->an_lock = amap->am_lock; |
| 606 | pg = uvm_pagealloc(NULL, ufi->orig_rvaddr, anon, |
| 607 | UVM_FLAG_COLORMATCH | (opg == NULL ? UVM_PGA_ZERO : 0)); |
| 608 | if (pg == NULL) { |
| 609 | anon->an_lock = NULL; |
| 610 | } |
| 611 | } else { |
| 612 | pg = NULL; |
| 613 | } |
| 614 | |
| 615 | /* |
| 616 | * out of memory resources? |
| 617 | */ |
| 618 | |
| 619 | if (pg == NULL) { |
| 620 | /* save anon for the next try. */ |
| 621 | if (anon != NULL) { |
| 622 | *spare = anon; |
| 623 | } |
| 624 | |
| 625 | /* unlock and fail ... */ |
| 626 | uvm_page_unbusy(&uobjpage, 1); |
| 627 | uvmfault_unlockall(ufi, amap, uobj); |
| 628 | if (!uvm_reclaimable()) { |
| 629 | UVMHIST_LOG(maphist, "out of VM" , 0,0,0,0); |
| 630 | uvmexp.fltnoanon++; |
| 631 | error = ENOMEM; |
| 632 | goto done; |
| 633 | } |
| 634 | |
| 635 | UVMHIST_LOG(maphist, "out of RAM, waiting for more" , 0,0,0,0); |
| 636 | uvmexp.fltnoram++; |
| 637 | uvm_wait("flt_noram5" ); |
| 638 | error = ERESTART; |
| 639 | goto done; |
| 640 | } |
| 641 | |
| 642 | /* copy page [pg now dirty] */ |
| 643 | if (opg) { |
| 644 | uvm_pagecopy(opg, pg); |
| 645 | } |
| 646 | |
| 647 | amap_add(&ufi->entry->aref, ufi->orig_rvaddr - ufi->entry->start, anon, |
| 648 | oanon != NULL); |
| 649 | |
| 650 | *nanon = anon; |
| 651 | error = 0; |
| 652 | done: |
| 653 | return error; |
| 654 | } |
| 655 | |
| 656 | |
| 657 | /* |
| 658 | * F A U L T - m a i n e n t r y p o i n t |
| 659 | */ |
| 660 | |
| 661 | /* |
| 662 | * uvm_fault: page fault handler |
| 663 | * |
| 664 | * => called from MD code to resolve a page fault |
| 665 | * => VM data structures usually should be unlocked. however, it is |
| 666 | * possible to call here with the main map locked if the caller |
| 667 | * gets a write lock, sets it recusive, and then calls us (c.f. |
| 668 | * uvm_map_pageable). this should be avoided because it keeps |
| 669 | * the map locked off during I/O. |
| 670 | * => MUST NEVER BE CALLED IN INTERRUPT CONTEXT |
| 671 | */ |
| 672 | |
| 673 | #define MASK(entry) (UVM_ET_ISCOPYONWRITE(entry) ? \ |
| 674 | ~VM_PROT_WRITE : VM_PROT_ALL) |
| 675 | |
| 676 | /* fault_flag values passed from uvm_fault_wire to uvm_fault_internal */ |
| 677 | #define UVM_FAULT_WIRE (1 << 0) |
| 678 | #define UVM_FAULT_MAXPROT (1 << 1) |
| 679 | |
| 680 | struct uvm_faultctx { |
| 681 | |
| 682 | /* |
| 683 | * the following members are set up by uvm_fault_check() and |
| 684 | * read-only after that. |
| 685 | * |
| 686 | * note that narrow is used by uvm_fault_check() to change |
| 687 | * the behaviour after ERESTART. |
| 688 | * |
| 689 | * most of them might change after RESTART if the underlying |
| 690 | * map entry has been changed behind us. an exception is |
| 691 | * wire_paging, which does never change. |
| 692 | */ |
| 693 | vm_prot_t access_type; |
| 694 | vaddr_t startva; |
| 695 | int npages; |
| 696 | int centeridx; |
| 697 | bool narrow; /* work on a single requested page only */ |
| 698 | bool wire_mapping; /* request a PMAP_WIRED mapping |
| 699 | (UVM_FAULT_WIRE or VM_MAPENT_ISWIRED) */ |
| 700 | bool wire_paging; /* request uvm_pagewire |
| 701 | (true for UVM_FAULT_WIRE) */ |
| 702 | bool cow_now; /* VM_PROT_WRITE is actually requested |
| 703 | (ie. should break COW and page loaning) */ |
| 704 | |
| 705 | /* |
| 706 | * enter_prot is set up by uvm_fault_check() and clamped |
| 707 | * (ie. drop the VM_PROT_WRITE bit) in various places in case |
| 708 | * of !cow_now. |
| 709 | */ |
| 710 | vm_prot_t enter_prot; /* prot at which we want to enter pages in */ |
| 711 | |
| 712 | /* |
| 713 | * the following member is for uvmfault_promote() and ERESTART. |
| 714 | */ |
| 715 | struct vm_anon *anon_spare; |
| 716 | |
| 717 | /* |
| 718 | * the folloing is actually a uvm_fault_lower() internal. |
| 719 | * it's here merely for debugging. |
| 720 | * (or due to the mechanical separation of the function?) |
| 721 | */ |
| 722 | bool promote; |
| 723 | }; |
| 724 | |
| 725 | static inline int uvm_fault_check( |
| 726 | struct uvm_faultinfo *, struct uvm_faultctx *, |
| 727 | struct vm_anon ***, bool); |
| 728 | |
| 729 | static int uvm_fault_upper( |
| 730 | struct uvm_faultinfo *, struct uvm_faultctx *, |
| 731 | struct vm_anon **); |
| 732 | static inline int uvm_fault_upper_lookup( |
| 733 | struct uvm_faultinfo *, const struct uvm_faultctx *, |
| 734 | struct vm_anon **, struct vm_page **); |
| 735 | static inline void uvm_fault_upper_neighbor( |
| 736 | struct uvm_faultinfo *, const struct uvm_faultctx *, |
| 737 | vaddr_t, struct vm_page *, bool); |
| 738 | static inline int uvm_fault_upper_loan( |
| 739 | struct uvm_faultinfo *, struct uvm_faultctx *, |
| 740 | struct vm_anon *, struct uvm_object **); |
| 741 | static inline int uvm_fault_upper_promote( |
| 742 | struct uvm_faultinfo *, struct uvm_faultctx *, |
| 743 | struct uvm_object *, struct vm_anon *); |
| 744 | static inline int uvm_fault_upper_direct( |
| 745 | struct uvm_faultinfo *, struct uvm_faultctx *, |
| 746 | struct uvm_object *, struct vm_anon *); |
| 747 | static int uvm_fault_upper_enter( |
| 748 | struct uvm_faultinfo *, const struct uvm_faultctx *, |
| 749 | struct uvm_object *, struct vm_anon *, |
| 750 | struct vm_page *, struct vm_anon *); |
| 751 | static inline void uvm_fault_upper_done( |
| 752 | struct uvm_faultinfo *, const struct uvm_faultctx *, |
| 753 | struct vm_anon *, struct vm_page *); |
| 754 | |
| 755 | static int uvm_fault_lower( |
| 756 | struct uvm_faultinfo *, struct uvm_faultctx *, |
| 757 | struct vm_page **); |
| 758 | static inline void uvm_fault_lower_lookup( |
| 759 | struct uvm_faultinfo *, const struct uvm_faultctx *, |
| 760 | struct vm_page **); |
| 761 | static inline void uvm_fault_lower_neighbor( |
| 762 | struct uvm_faultinfo *, const struct uvm_faultctx *, |
| 763 | vaddr_t, struct vm_page *, bool); |
| 764 | static inline int uvm_fault_lower_io( |
| 765 | struct uvm_faultinfo *, const struct uvm_faultctx *, |
| 766 | struct uvm_object **, struct vm_page **); |
| 767 | static inline int uvm_fault_lower_direct( |
| 768 | struct uvm_faultinfo *, struct uvm_faultctx *, |
| 769 | struct uvm_object *, struct vm_page *); |
| 770 | static inline int uvm_fault_lower_direct_loan( |
| 771 | struct uvm_faultinfo *, struct uvm_faultctx *, |
| 772 | struct uvm_object *, struct vm_page **, |
| 773 | struct vm_page **); |
| 774 | static inline int uvm_fault_lower_promote( |
| 775 | struct uvm_faultinfo *, struct uvm_faultctx *, |
| 776 | struct uvm_object *, struct vm_page *); |
| 777 | static int uvm_fault_lower_enter( |
| 778 | struct uvm_faultinfo *, const struct uvm_faultctx *, |
| 779 | struct uvm_object *, |
| 780 | struct vm_anon *, struct vm_page *); |
| 781 | static inline void uvm_fault_lower_done( |
| 782 | struct uvm_faultinfo *, const struct uvm_faultctx *, |
| 783 | struct uvm_object *, struct vm_page *); |
| 784 | |
| 785 | int |
| 786 | uvm_fault_internal(struct vm_map *orig_map, vaddr_t vaddr, |
| 787 | vm_prot_t access_type, int fault_flag) |
| 788 | { |
| 789 | struct cpu_data *cd; |
| 790 | struct uvm_cpu *ucpu; |
| 791 | struct uvm_faultinfo ufi; |
| 792 | struct uvm_faultctx flt = { |
| 793 | .access_type = access_type, |
| 794 | |
| 795 | /* don't look for neighborhood * pages on "wire" fault */ |
| 796 | .narrow = (fault_flag & UVM_FAULT_WIRE) != 0, |
| 797 | |
| 798 | /* "wire" fault causes wiring of both mapping and paging */ |
| 799 | .wire_mapping = (fault_flag & UVM_FAULT_WIRE) != 0, |
| 800 | .wire_paging = (fault_flag & UVM_FAULT_WIRE) != 0, |
| 801 | }; |
| 802 | const bool maxprot = (fault_flag & UVM_FAULT_MAXPROT) != 0; |
| 803 | struct vm_anon *anons_store[UVM_MAXRANGE], **anons; |
| 804 | struct vm_page *pages_store[UVM_MAXRANGE], **pages; |
| 805 | int error; |
| 806 | |
| 807 | UVMHIST_FUNC("uvm_fault" ); UVMHIST_CALLED(maphist); |
| 808 | |
| 809 | UVMHIST_LOG(maphist, "(map=%p, vaddr=%#lx, at=%d, ff=%d)" , |
| 810 | orig_map, vaddr, access_type, fault_flag); |
| 811 | |
| 812 | cd = &(curcpu()->ci_data); |
| 813 | cd->cpu_nfault++; |
| 814 | ucpu = cd->cpu_uvm; |
| 815 | |
| 816 | /* Don't flood RNG subsystem with samples. */ |
| 817 | if (cd->cpu_nfault % 503) |
| 818 | goto norng; |
| 819 | |
| 820 | /* Don't count anything until user interaction is possible */ |
| 821 | if (__predict_true(start_init_exec)) { |
| 822 | kpreempt_disable(); |
| 823 | rnd_add_uint32(&ucpu->rs, |
| 824 | sizeof(vaddr_t) == sizeof(uint32_t) ? |
| 825 | (uint32_t)vaddr : sizeof(vaddr_t) == |
| 826 | sizeof(uint64_t) ? |
| 827 | (uint32_t)(vaddr & 0x00000000ffffffff) : |
| 828 | (uint32_t)(cd->cpu_nfault & 0x00000000ffffffff)); |
| 829 | kpreempt_enable(); |
| 830 | } |
| 831 | norng: |
| 832 | /* |
| 833 | * init the IN parameters in the ufi |
| 834 | */ |
| 835 | |
| 836 | ufi.orig_map = orig_map; |
| 837 | ufi.orig_rvaddr = trunc_page(vaddr); |
| 838 | ufi.orig_size = PAGE_SIZE; /* can't get any smaller than this */ |
| 839 | |
| 840 | error = ERESTART; |
| 841 | while (error == ERESTART) { /* ReFault: */ |
| 842 | anons = anons_store; |
| 843 | pages = pages_store; |
| 844 | |
| 845 | error = uvm_fault_check(&ufi, &flt, &anons, maxprot); |
| 846 | if (error != 0) |
| 847 | continue; |
| 848 | |
| 849 | error = uvm_fault_upper_lookup(&ufi, &flt, anons, pages); |
| 850 | if (error != 0) |
| 851 | continue; |
| 852 | |
| 853 | if (pages[flt.centeridx] == PGO_DONTCARE) |
| 854 | error = uvm_fault_upper(&ufi, &flt, anons); |
| 855 | else { |
| 856 | struct uvm_object * const uobj = |
| 857 | ufi.entry->object.uvm_obj; |
| 858 | |
| 859 | if (uobj && uobj->pgops->pgo_fault != NULL) { |
| 860 | /* |
| 861 | * invoke "special" fault routine. |
| 862 | */ |
| 863 | mutex_enter(uobj->vmobjlock); |
| 864 | /* locked: maps(read), amap(if there), uobj */ |
| 865 | error = uobj->pgops->pgo_fault(&ufi, |
| 866 | flt.startva, pages, flt.npages, |
| 867 | flt.centeridx, flt.access_type, |
| 868 | PGO_LOCKED|PGO_SYNCIO); |
| 869 | |
| 870 | /* |
| 871 | * locked: nothing, pgo_fault has unlocked |
| 872 | * everything |
| 873 | */ |
| 874 | |
| 875 | /* |
| 876 | * object fault routine responsible for |
| 877 | * pmap_update(). |
| 878 | */ |
| 879 | } else { |
| 880 | error = uvm_fault_lower(&ufi, &flt, pages); |
| 881 | } |
| 882 | } |
| 883 | } |
| 884 | |
| 885 | if (flt.anon_spare != NULL) { |
| 886 | flt.anon_spare->an_ref--; |
| 887 | KASSERT(flt.anon_spare->an_ref == 0); |
| 888 | KASSERT(flt.anon_spare->an_lock == NULL); |
| 889 | uvm_anon_free(flt.anon_spare); |
| 890 | } |
| 891 | return error; |
| 892 | } |
| 893 | |
| 894 | /* |
| 895 | * uvm_fault_check: check prot, handle needs-copy, etc. |
| 896 | * |
| 897 | * 1. lookup entry. |
| 898 | * 2. check protection. |
| 899 | * 3. adjust fault condition (mainly for simulated fault). |
| 900 | * 4. handle needs-copy (lazy amap copy). |
| 901 | * 5. establish range of interest for neighbor fault (aka pre-fault). |
| 902 | * 6. look up anons (if amap exists). |
| 903 | * 7. flush pages (if MADV_SEQUENTIAL) |
| 904 | * |
| 905 | * => called with nothing locked. |
| 906 | * => if we fail (result != 0) we unlock everything. |
| 907 | * => initialize/adjust many members of flt. |
| 908 | */ |
| 909 | |
| 910 | static int |
| 911 | uvm_fault_check( |
| 912 | struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, |
| 913 | struct vm_anon ***ranons, bool maxprot) |
| 914 | { |
| 915 | struct vm_amap *amap; |
| 916 | struct uvm_object *uobj; |
| 917 | vm_prot_t check_prot; |
| 918 | int nback, nforw; |
| 919 | UVMHIST_FUNC("uvm_fault_check" ); UVMHIST_CALLED(maphist); |
| 920 | |
| 921 | /* |
| 922 | * lookup and lock the maps |
| 923 | */ |
| 924 | |
| 925 | if (uvmfault_lookup(ufi, false) == false) { |
| 926 | UVMHIST_LOG(maphist, "<- no mapping @ 0x%x" , ufi->orig_rvaddr, |
| 927 | 0,0,0); |
| 928 | return EFAULT; |
| 929 | } |
| 930 | /* locked: maps(read) */ |
| 931 | |
| 932 | #ifdef DIAGNOSTIC |
| 933 | if ((ufi->map->flags & VM_MAP_PAGEABLE) == 0) { |
| 934 | printf("Page fault on non-pageable map:\n" ); |
| 935 | printf("ufi->map = %p\n" , ufi->map); |
| 936 | printf("ufi->orig_map = %p\n" , ufi->orig_map); |
| 937 | printf("ufi->orig_rvaddr = 0x%lx\n" , (u_long) ufi->orig_rvaddr); |
| 938 | panic("uvm_fault: (ufi->map->flags & VM_MAP_PAGEABLE) == 0" ); |
| 939 | } |
| 940 | #endif |
| 941 | |
| 942 | /* |
| 943 | * check protection |
| 944 | */ |
| 945 | |
| 946 | check_prot = maxprot ? |
| 947 | ufi->entry->max_protection : ufi->entry->protection; |
| 948 | if ((check_prot & flt->access_type) != flt->access_type) { |
| 949 | UVMHIST_LOG(maphist, |
| 950 | "<- protection failure (prot=%#x, access=%#x)" , |
| 951 | ufi->entry->protection, flt->access_type, 0, 0); |
| 952 | uvmfault_unlockmaps(ufi, false); |
| 953 | return EACCES; |
| 954 | } |
| 955 | |
| 956 | /* |
| 957 | * "enter_prot" is the protection we want to enter the page in at. |
| 958 | * for certain pages (e.g. copy-on-write pages) this protection can |
| 959 | * be more strict than ufi->entry->protection. "wired" means either |
| 960 | * the entry is wired or we are fault-wiring the pg. |
| 961 | */ |
| 962 | |
| 963 | flt->enter_prot = ufi->entry->protection; |
| 964 | if (VM_MAPENT_ISWIRED(ufi->entry)) |
| 965 | flt->wire_mapping = true; |
| 966 | |
| 967 | if (flt->wire_mapping) { |
| 968 | flt->access_type = flt->enter_prot; /* full access for wired */ |
| 969 | flt->cow_now = (check_prot & VM_PROT_WRITE) != 0; |
| 970 | } else { |
| 971 | flt->cow_now = (flt->access_type & VM_PROT_WRITE) != 0; |
| 972 | } |
| 973 | |
| 974 | flt->promote = false; |
| 975 | |
| 976 | /* |
| 977 | * handle "needs_copy" case. if we need to copy the amap we will |
| 978 | * have to drop our readlock and relock it with a write lock. (we |
| 979 | * need a write lock to change anything in a map entry [e.g. |
| 980 | * needs_copy]). |
| 981 | */ |
| 982 | |
| 983 | if (UVM_ET_ISNEEDSCOPY(ufi->entry)) { |
| 984 | if (flt->cow_now || (ufi->entry->object.uvm_obj == NULL)) { |
| 985 | KASSERT(!maxprot); |
| 986 | /* need to clear */ |
| 987 | UVMHIST_LOG(maphist, |
| 988 | " need to clear needs_copy and refault" ,0,0,0,0); |
| 989 | uvmfault_unlockmaps(ufi, false); |
| 990 | uvmfault_amapcopy(ufi); |
| 991 | uvmexp.fltamcopy++; |
| 992 | return ERESTART; |
| 993 | |
| 994 | } else { |
| 995 | |
| 996 | /* |
| 997 | * ensure that we pmap_enter page R/O since |
| 998 | * needs_copy is still true |
| 999 | */ |
| 1000 | |
| 1001 | flt->enter_prot &= ~VM_PROT_WRITE; |
| 1002 | } |
| 1003 | } |
| 1004 | |
| 1005 | /* |
| 1006 | * identify the players |
| 1007 | */ |
| 1008 | |
| 1009 | amap = ufi->entry->aref.ar_amap; /* upper layer */ |
| 1010 | uobj = ufi->entry->object.uvm_obj; /* lower layer */ |
| 1011 | |
| 1012 | /* |
| 1013 | * check for a case 0 fault. if nothing backing the entry then |
| 1014 | * error now. |
| 1015 | */ |
| 1016 | |
| 1017 | if (amap == NULL && uobj == NULL) { |
| 1018 | uvmfault_unlockmaps(ufi, false); |
| 1019 | UVMHIST_LOG(maphist,"<- no backing store, no overlay" ,0,0,0,0); |
| 1020 | return EFAULT; |
| 1021 | } |
| 1022 | |
| 1023 | /* |
| 1024 | * establish range of interest based on advice from mapper |
| 1025 | * and then clip to fit map entry. note that we only want |
| 1026 | * to do this the first time through the fault. if we |
| 1027 | * ReFault we will disable this by setting "narrow" to true. |
| 1028 | */ |
| 1029 | |
| 1030 | if (flt->narrow == false) { |
| 1031 | |
| 1032 | /* wide fault (!narrow) */ |
| 1033 | KASSERT(uvmadvice[ufi->entry->advice].advice == |
| 1034 | ufi->entry->advice); |
| 1035 | nback = MIN(uvmadvice[ufi->entry->advice].nback, |
| 1036 | (ufi->orig_rvaddr - ufi->entry->start) >> PAGE_SHIFT); |
| 1037 | flt->startva = ufi->orig_rvaddr - (nback << PAGE_SHIFT); |
| 1038 | /* |
| 1039 | * note: "-1" because we don't want to count the |
| 1040 | * faulting page as forw |
| 1041 | */ |
| 1042 | nforw = MIN(uvmadvice[ufi->entry->advice].nforw, |
| 1043 | ((ufi->entry->end - ufi->orig_rvaddr) >> |
| 1044 | PAGE_SHIFT) - 1); |
| 1045 | flt->npages = nback + nforw + 1; |
| 1046 | flt->centeridx = nback; |
| 1047 | |
| 1048 | flt->narrow = true; /* ensure only once per-fault */ |
| 1049 | |
| 1050 | } else { |
| 1051 | |
| 1052 | /* narrow fault! */ |
| 1053 | nback = nforw = 0; |
| 1054 | flt->startva = ufi->orig_rvaddr; |
| 1055 | flt->npages = 1; |
| 1056 | flt->centeridx = 0; |
| 1057 | |
| 1058 | } |
| 1059 | /* offset from entry's start to pgs' start */ |
| 1060 | const voff_t eoff = flt->startva - ufi->entry->start; |
| 1061 | |
| 1062 | /* locked: maps(read) */ |
| 1063 | UVMHIST_LOG(maphist, " narrow=%d, back=%d, forw=%d, startva=%#lx" , |
| 1064 | flt->narrow, nback, nforw, flt->startva); |
| 1065 | UVMHIST_LOG(maphist, " entry=%p, amap=%p, obj=%p" , ufi->entry, |
| 1066 | amap, uobj, 0); |
| 1067 | |
| 1068 | /* |
| 1069 | * if we've got an amap, lock it and extract current anons. |
| 1070 | */ |
| 1071 | |
| 1072 | if (amap) { |
| 1073 | amap_lock(amap); |
| 1074 | amap_lookups(&ufi->entry->aref, eoff, *ranons, flt->npages); |
| 1075 | } else { |
| 1076 | *ranons = NULL; /* to be safe */ |
| 1077 | } |
| 1078 | |
| 1079 | /* locked: maps(read), amap(if there) */ |
| 1080 | KASSERT(amap == NULL || mutex_owned(amap->am_lock)); |
| 1081 | |
| 1082 | /* |
| 1083 | * for MADV_SEQUENTIAL mappings we want to deactivate the back pages |
| 1084 | * now and then forget about them (for the rest of the fault). |
| 1085 | */ |
| 1086 | |
| 1087 | if (ufi->entry->advice == MADV_SEQUENTIAL && nback != 0) { |
| 1088 | |
| 1089 | UVMHIST_LOG(maphist, " MADV_SEQUENTIAL: flushing backpages" , |
| 1090 | 0,0,0,0); |
| 1091 | /* flush back-page anons? */ |
| 1092 | if (amap) |
| 1093 | uvmfault_anonflush(*ranons, nback); |
| 1094 | |
| 1095 | /* flush object? */ |
| 1096 | if (uobj) { |
| 1097 | voff_t uoff; |
| 1098 | |
| 1099 | uoff = ufi->entry->offset + eoff; |
| 1100 | mutex_enter(uobj->vmobjlock); |
| 1101 | (void) (uobj->pgops->pgo_put)(uobj, uoff, uoff + |
| 1102 | (nback << PAGE_SHIFT), PGO_DEACTIVATE); |
| 1103 | } |
| 1104 | |
| 1105 | /* now forget about the backpages */ |
| 1106 | if (amap) |
| 1107 | *ranons += nback; |
| 1108 | flt->startva += (nback << PAGE_SHIFT); |
| 1109 | flt->npages -= nback; |
| 1110 | flt->centeridx = 0; |
| 1111 | } |
| 1112 | /* |
| 1113 | * => startva is fixed |
| 1114 | * => npages is fixed |
| 1115 | */ |
| 1116 | KASSERT(flt->startva <= ufi->orig_rvaddr); |
| 1117 | KASSERT(ufi->orig_rvaddr + ufi->orig_size <= |
| 1118 | flt->startva + (flt->npages << PAGE_SHIFT)); |
| 1119 | return 0; |
| 1120 | } |
| 1121 | |
| 1122 | /* |
| 1123 | * uvm_fault_upper_lookup: look up existing h/w mapping and amap. |
| 1124 | * |
| 1125 | * iterate range of interest: |
| 1126 | * 1. check if h/w mapping exists. if yes, we don't care |
| 1127 | * 2. check if anon exists. if not, page is lower. |
| 1128 | * 3. if anon exists, enter h/w mapping for neighbors. |
| 1129 | * |
| 1130 | * => called with amap locked (if exists). |
| 1131 | */ |
| 1132 | |
| 1133 | static int |
| 1134 | uvm_fault_upper_lookup( |
| 1135 | struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, |
| 1136 | struct vm_anon **anons, struct vm_page **pages) |
| 1137 | { |
| 1138 | struct vm_amap *amap = ufi->entry->aref.ar_amap; |
| 1139 | int lcv; |
| 1140 | vaddr_t currva; |
| 1141 | bool shadowed __unused; |
| 1142 | UVMHIST_FUNC("uvm_fault_upper_lookup" ); UVMHIST_CALLED(maphist); |
| 1143 | |
| 1144 | /* locked: maps(read), amap(if there) */ |
| 1145 | KASSERT(amap == NULL || mutex_owned(amap->am_lock)); |
| 1146 | |
| 1147 | /* |
| 1148 | * map in the backpages and frontpages we found in the amap in hopes |
| 1149 | * of preventing future faults. we also init the pages[] array as |
| 1150 | * we go. |
| 1151 | */ |
| 1152 | |
| 1153 | currva = flt->startva; |
| 1154 | shadowed = false; |
| 1155 | for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { |
| 1156 | /* |
| 1157 | * don't play with VAs that are already mapped |
| 1158 | * (except for center) |
| 1159 | */ |
| 1160 | if (lcv != flt->centeridx && |
| 1161 | pmap_extract(ufi->orig_map->pmap, currva, NULL)) { |
| 1162 | pages[lcv] = PGO_DONTCARE; |
| 1163 | continue; |
| 1164 | } |
| 1165 | |
| 1166 | /* |
| 1167 | * unmapped or center page. check if any anon at this level. |
| 1168 | */ |
| 1169 | if (amap == NULL || anons[lcv] == NULL) { |
| 1170 | pages[lcv] = NULL; |
| 1171 | continue; |
| 1172 | } |
| 1173 | |
| 1174 | /* |
| 1175 | * check for present page and map if possible. re-activate it. |
| 1176 | */ |
| 1177 | |
| 1178 | pages[lcv] = PGO_DONTCARE; |
| 1179 | if (lcv == flt->centeridx) { /* save center for later! */ |
| 1180 | shadowed = true; |
| 1181 | continue; |
| 1182 | } |
| 1183 | |
| 1184 | struct vm_anon *anon = anons[lcv]; |
| 1185 | struct vm_page *pg = anon->an_page; |
| 1186 | |
| 1187 | KASSERT(anon->an_lock == amap->am_lock); |
| 1188 | |
| 1189 | /* Ignore loaned and busy pages. */ |
| 1190 | if (pg && pg->loan_count == 0 && (pg->flags & PG_BUSY) == 0) { |
| 1191 | uvm_fault_upper_neighbor(ufi, flt, currva, |
| 1192 | pg, anon->an_ref > 1); |
| 1193 | } |
| 1194 | } |
| 1195 | |
| 1196 | /* locked: maps(read), amap(if there) */ |
| 1197 | KASSERT(amap == NULL || mutex_owned(amap->am_lock)); |
| 1198 | /* (shadowed == true) if there is an anon at the faulting address */ |
| 1199 | UVMHIST_LOG(maphist, " shadowed=%d, will_get=%d" , shadowed, |
| 1200 | (ufi->entry->object.uvm_obj && shadowed != false),0,0); |
| 1201 | |
| 1202 | /* |
| 1203 | * note that if we are really short of RAM we could sleep in the above |
| 1204 | * call to pmap_enter with everything locked. bad? |
| 1205 | * |
| 1206 | * XXX Actually, that is bad; pmap_enter() should just fail in that |
| 1207 | * XXX case. --thorpej |
| 1208 | */ |
| 1209 | |
| 1210 | return 0; |
| 1211 | } |
| 1212 | |
| 1213 | /* |
| 1214 | * uvm_fault_upper_neighbor: enter single lower neighbor page. |
| 1215 | * |
| 1216 | * => called with amap and anon locked. |
| 1217 | */ |
| 1218 | |
| 1219 | static void |
| 1220 | uvm_fault_upper_neighbor( |
| 1221 | struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, |
| 1222 | vaddr_t currva, struct vm_page *pg, bool readonly) |
| 1223 | { |
| 1224 | UVMHIST_FUNC("uvm_fault_upper_neighbor" ); UVMHIST_CALLED(maphist); |
| 1225 | |
| 1226 | /* locked: amap, anon */ |
| 1227 | |
| 1228 | mutex_enter(&uvm_pageqlock); |
| 1229 | uvm_pageenqueue(pg); |
| 1230 | mutex_exit(&uvm_pageqlock); |
| 1231 | UVMHIST_LOG(maphist, |
| 1232 | " MAPPING: n anon: pm=%p, va=%#lx, pg=%p" , |
| 1233 | ufi->orig_map->pmap, currva, pg, 0); |
| 1234 | uvmexp.fltnamap++; |
| 1235 | |
| 1236 | /* |
| 1237 | * Since this page isn't the page that's actually faulting, |
| 1238 | * ignore pmap_enter() failures; it's not critical that we |
| 1239 | * enter these right now. |
| 1240 | */ |
| 1241 | |
| 1242 | (void) pmap_enter(ufi->orig_map->pmap, currva, |
| 1243 | VM_PAGE_TO_PHYS(pg), |
| 1244 | readonly ? (flt->enter_prot & ~VM_PROT_WRITE) : |
| 1245 | flt->enter_prot, |
| 1246 | PMAP_CANFAIL | (flt->wire_mapping ? PMAP_WIRED : 0)); |
| 1247 | |
| 1248 | pmap_update(ufi->orig_map->pmap); |
| 1249 | } |
| 1250 | |
| 1251 | /* |
| 1252 | * uvm_fault_upper: handle upper fault. |
| 1253 | * |
| 1254 | * 1. acquire anon lock. |
| 1255 | * 2. get anon. let uvmfault_anonget do the dirty work. |
| 1256 | * 3. handle loan. |
| 1257 | * 4. dispatch direct or promote handlers. |
| 1258 | */ |
| 1259 | |
| 1260 | static int |
| 1261 | uvm_fault_upper( |
| 1262 | struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, |
| 1263 | struct vm_anon **anons) |
| 1264 | { |
| 1265 | struct vm_amap * const amap = ufi->entry->aref.ar_amap; |
| 1266 | struct vm_anon * const anon = anons[flt->centeridx]; |
| 1267 | struct uvm_object *uobj; |
| 1268 | int error; |
| 1269 | UVMHIST_FUNC("uvm_fault_upper" ); UVMHIST_CALLED(maphist); |
| 1270 | |
| 1271 | /* locked: maps(read), amap, anon */ |
| 1272 | KASSERT(mutex_owned(amap->am_lock)); |
| 1273 | KASSERT(anon->an_lock == amap->am_lock); |
| 1274 | |
| 1275 | /* |
| 1276 | * handle case 1: fault on an anon in our amap |
| 1277 | */ |
| 1278 | |
| 1279 | UVMHIST_LOG(maphist, " case 1 fault: anon=%p" , anon, 0,0,0); |
| 1280 | |
| 1281 | /* |
| 1282 | * no matter if we have case 1A or case 1B we are going to need to |
| 1283 | * have the anon's memory resident. ensure that now. |
| 1284 | */ |
| 1285 | |
| 1286 | /* |
| 1287 | * let uvmfault_anonget do the dirty work. |
| 1288 | * if it fails (!OK) it will unlock everything for us. |
| 1289 | * if it succeeds, locks are still valid and locked. |
| 1290 | * also, if it is OK, then the anon's page is on the queues. |
| 1291 | * if the page is on loan from a uvm_object, then anonget will |
| 1292 | * lock that object for us if it does not fail. |
| 1293 | */ |
| 1294 | |
| 1295 | error = uvmfault_anonget(ufi, amap, anon); |
| 1296 | switch (error) { |
| 1297 | case 0: |
| 1298 | break; |
| 1299 | |
| 1300 | case ERESTART: |
| 1301 | return ERESTART; |
| 1302 | |
| 1303 | case EAGAIN: |
| 1304 | kpause("fltagain1" , false, hz/2, NULL); |
| 1305 | return ERESTART; |
| 1306 | |
| 1307 | default: |
| 1308 | return error; |
| 1309 | } |
| 1310 | |
| 1311 | /* |
| 1312 | * uobj is non null if the page is on loan from an object (i.e. uobj) |
| 1313 | */ |
| 1314 | |
| 1315 | uobj = anon->an_page->uobject; /* locked by anonget if !NULL */ |
| 1316 | |
| 1317 | /* locked: maps(read), amap, anon, uobj(if one) */ |
| 1318 | KASSERT(mutex_owned(amap->am_lock)); |
| 1319 | KASSERT(anon->an_lock == amap->am_lock); |
| 1320 | KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); |
| 1321 | |
| 1322 | /* |
| 1323 | * special handling for loaned pages |
| 1324 | */ |
| 1325 | |
| 1326 | if (anon->an_page->loan_count) { |
| 1327 | error = uvm_fault_upper_loan(ufi, flt, anon, &uobj); |
| 1328 | if (error != 0) |
| 1329 | return error; |
| 1330 | } |
| 1331 | |
| 1332 | /* |
| 1333 | * if we are case 1B then we will need to allocate a new blank |
| 1334 | * anon to transfer the data into. note that we have a lock |
| 1335 | * on anon, so no one can busy or release the page until we are done. |
| 1336 | * also note that the ref count can't drop to zero here because |
| 1337 | * it is > 1 and we are only dropping one ref. |
| 1338 | * |
| 1339 | * in the (hopefully very rare) case that we are out of RAM we |
| 1340 | * will unlock, wait for more RAM, and refault. |
| 1341 | * |
| 1342 | * if we are out of anon VM we kill the process (XXX: could wait?). |
| 1343 | */ |
| 1344 | |
| 1345 | if (flt->cow_now && anon->an_ref > 1) { |
| 1346 | flt->promote = true; |
| 1347 | error = uvm_fault_upper_promote(ufi, flt, uobj, anon); |
| 1348 | } else { |
| 1349 | error = uvm_fault_upper_direct(ufi, flt, uobj, anon); |
| 1350 | } |
| 1351 | return error; |
| 1352 | } |
| 1353 | |
| 1354 | /* |
| 1355 | * uvm_fault_upper_loan: handle loaned upper page. |
| 1356 | * |
| 1357 | * 1. if not cow'ing now, simply adjust flt->enter_prot. |
| 1358 | * 2. if cow'ing now, and if ref count is 1, break loan. |
| 1359 | */ |
| 1360 | |
| 1361 | static int |
| 1362 | uvm_fault_upper_loan( |
| 1363 | struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, |
| 1364 | struct vm_anon *anon, struct uvm_object **ruobj) |
| 1365 | { |
| 1366 | struct vm_amap * const amap = ufi->entry->aref.ar_amap; |
| 1367 | int error = 0; |
| 1368 | UVMHIST_FUNC("uvm_fault_upper_loan" ); UVMHIST_CALLED(maphist); |
| 1369 | |
| 1370 | if (!flt->cow_now) { |
| 1371 | |
| 1372 | /* |
| 1373 | * for read faults on loaned pages we just cap the |
| 1374 | * protection at read-only. |
| 1375 | */ |
| 1376 | |
| 1377 | flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; |
| 1378 | |
| 1379 | } else { |
| 1380 | /* |
| 1381 | * note that we can't allow writes into a loaned page! |
| 1382 | * |
| 1383 | * if we have a write fault on a loaned page in an |
| 1384 | * anon then we need to look at the anon's ref count. |
| 1385 | * if it is greater than one then we are going to do |
| 1386 | * a normal copy-on-write fault into a new anon (this |
| 1387 | * is not a problem). however, if the reference count |
| 1388 | * is one (a case where we would normally allow a |
| 1389 | * write directly to the page) then we need to kill |
| 1390 | * the loan before we continue. |
| 1391 | */ |
| 1392 | |
| 1393 | /* >1 case is already ok */ |
| 1394 | if (anon->an_ref == 1) { |
| 1395 | error = uvm_loanbreak_anon(anon, *ruobj); |
| 1396 | if (error != 0) { |
| 1397 | uvmfault_unlockall(ufi, amap, *ruobj); |
| 1398 | uvm_wait("flt_noram2" ); |
| 1399 | return ERESTART; |
| 1400 | } |
| 1401 | /* if we were a loan reciever uobj is gone */ |
| 1402 | if (*ruobj) |
| 1403 | *ruobj = NULL; |
| 1404 | } |
| 1405 | } |
| 1406 | return error; |
| 1407 | } |
| 1408 | |
| 1409 | /* |
| 1410 | * uvm_fault_upper_promote: promote upper page. |
| 1411 | * |
| 1412 | * 1. call uvmfault_promote. |
| 1413 | * 2. enqueue page. |
| 1414 | * 3. deref. |
| 1415 | * 4. pass page to uvm_fault_upper_enter. |
| 1416 | */ |
| 1417 | |
| 1418 | static int |
| 1419 | uvm_fault_upper_promote( |
| 1420 | struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, |
| 1421 | struct uvm_object *uobj, struct vm_anon *anon) |
| 1422 | { |
| 1423 | struct vm_anon * const oanon = anon; |
| 1424 | struct vm_page *pg; |
| 1425 | int error; |
| 1426 | UVMHIST_FUNC("uvm_fault_upper_promote" ); UVMHIST_CALLED(maphist); |
| 1427 | |
| 1428 | UVMHIST_LOG(maphist, " case 1B: COW fault" ,0,0,0,0); |
| 1429 | uvmexp.flt_acow++; |
| 1430 | |
| 1431 | error = uvmfault_promote(ufi, oanon, PGO_DONTCARE, &anon, |
| 1432 | &flt->anon_spare); |
| 1433 | switch (error) { |
| 1434 | case 0: |
| 1435 | break; |
| 1436 | case ERESTART: |
| 1437 | return ERESTART; |
| 1438 | default: |
| 1439 | return error; |
| 1440 | } |
| 1441 | |
| 1442 | KASSERT(anon == NULL || anon->an_lock == oanon->an_lock); |
| 1443 | |
| 1444 | pg = anon->an_page; |
| 1445 | mutex_enter(&uvm_pageqlock); |
| 1446 | uvm_pageenqueue(pg); /* uvm_fault_upper_done will activate the page */ |
| 1447 | mutex_exit(&uvm_pageqlock); |
| 1448 | pg->flags &= ~(PG_BUSY|PG_FAKE); |
| 1449 | UVM_PAGE_OWN(pg, NULL); |
| 1450 | |
| 1451 | /* deref: can not drop to zero here by defn! */ |
| 1452 | KASSERT(oanon->an_ref > 1); |
| 1453 | oanon->an_ref--; |
| 1454 | |
| 1455 | /* |
| 1456 | * note: oanon is still locked, as is the new anon. we |
| 1457 | * need to check for this later when we unlock oanon; if |
| 1458 | * oanon != anon, we'll have to unlock anon, too. |
| 1459 | */ |
| 1460 | |
| 1461 | return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon); |
| 1462 | } |
| 1463 | |
| 1464 | /* |
| 1465 | * uvm_fault_upper_direct: handle direct fault. |
| 1466 | */ |
| 1467 | |
| 1468 | static int |
| 1469 | uvm_fault_upper_direct( |
| 1470 | struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, |
| 1471 | struct uvm_object *uobj, struct vm_anon *anon) |
| 1472 | { |
| 1473 | struct vm_anon * const oanon = anon; |
| 1474 | struct vm_page *pg; |
| 1475 | UVMHIST_FUNC("uvm_fault_upper_direct" ); UVMHIST_CALLED(maphist); |
| 1476 | |
| 1477 | uvmexp.flt_anon++; |
| 1478 | pg = anon->an_page; |
| 1479 | if (anon->an_ref > 1) /* disallow writes to ref > 1 anons */ |
| 1480 | flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; |
| 1481 | |
| 1482 | return uvm_fault_upper_enter(ufi, flt, uobj, anon, pg, oanon); |
| 1483 | } |
| 1484 | |
| 1485 | /* |
| 1486 | * uvm_fault_upper_enter: enter h/w mapping of upper page. |
| 1487 | */ |
| 1488 | |
| 1489 | static int |
| 1490 | uvm_fault_upper_enter( |
| 1491 | struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, |
| 1492 | struct uvm_object *uobj, struct vm_anon *anon, struct vm_page *pg, |
| 1493 | struct vm_anon *oanon) |
| 1494 | { |
| 1495 | struct vm_amap * const amap = ufi->entry->aref.ar_amap; |
| 1496 | UVMHIST_FUNC("uvm_fault_upper_enter" ); UVMHIST_CALLED(maphist); |
| 1497 | |
| 1498 | /* locked: maps(read), amap, oanon, anon(if different from oanon) */ |
| 1499 | KASSERT(mutex_owned(amap->am_lock)); |
| 1500 | KASSERT(anon->an_lock == amap->am_lock); |
| 1501 | KASSERT(oanon->an_lock == amap->am_lock); |
| 1502 | KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); |
| 1503 | |
| 1504 | /* |
| 1505 | * now map the page in. |
| 1506 | */ |
| 1507 | |
| 1508 | UVMHIST_LOG(maphist, |
| 1509 | " MAPPING: anon: pm=%p, va=%#lx, pg=%p, promote=%d" , |
| 1510 | ufi->orig_map->pmap, ufi->orig_rvaddr, pg, flt->promote); |
| 1511 | if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr, |
| 1512 | VM_PAGE_TO_PHYS(pg), |
| 1513 | flt->enter_prot, flt->access_type | PMAP_CANFAIL | |
| 1514 | (flt->wire_mapping ? PMAP_WIRED : 0)) != 0) { |
| 1515 | |
| 1516 | /* |
| 1517 | * No need to undo what we did; we can simply think of |
| 1518 | * this as the pmap throwing away the mapping information. |
| 1519 | * |
| 1520 | * We do, however, have to go through the ReFault path, |
| 1521 | * as the map may change while we're asleep. |
| 1522 | */ |
| 1523 | |
| 1524 | uvmfault_unlockall(ufi, amap, uobj); |
| 1525 | if (!uvm_reclaimable()) { |
| 1526 | UVMHIST_LOG(maphist, |
| 1527 | "<- failed. out of VM" ,0,0,0,0); |
| 1528 | /* XXX instrumentation */ |
| 1529 | return ENOMEM; |
| 1530 | } |
| 1531 | /* XXX instrumentation */ |
| 1532 | uvm_wait("flt_pmfail1" ); |
| 1533 | return ERESTART; |
| 1534 | } |
| 1535 | |
| 1536 | uvm_fault_upper_done(ufi, flt, anon, pg); |
| 1537 | |
| 1538 | /* |
| 1539 | * done case 1! finish up by unlocking everything and returning success |
| 1540 | */ |
| 1541 | |
| 1542 | pmap_update(ufi->orig_map->pmap); |
| 1543 | uvmfault_unlockall(ufi, amap, uobj); |
| 1544 | return 0; |
| 1545 | } |
| 1546 | |
| 1547 | /* |
| 1548 | * uvm_fault_upper_done: queue upper center page. |
| 1549 | */ |
| 1550 | |
| 1551 | static void |
| 1552 | uvm_fault_upper_done( |
| 1553 | struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, |
| 1554 | struct vm_anon *anon, struct vm_page *pg) |
| 1555 | { |
| 1556 | const bool wire_paging = flt->wire_paging; |
| 1557 | |
| 1558 | UVMHIST_FUNC("uvm_fault_upper_done" ); UVMHIST_CALLED(maphist); |
| 1559 | |
| 1560 | /* |
| 1561 | * ... update the page queues. |
| 1562 | */ |
| 1563 | |
| 1564 | mutex_enter(&uvm_pageqlock); |
| 1565 | if (wire_paging) { |
| 1566 | uvm_pagewire(pg); |
| 1567 | |
| 1568 | /* |
| 1569 | * since the now-wired page cannot be paged out, |
| 1570 | * release its swap resources for others to use. |
| 1571 | * since an anon with no swap cannot be PG_CLEAN, |
| 1572 | * clear its clean flag now. |
| 1573 | */ |
| 1574 | |
| 1575 | pg->flags &= ~(PG_CLEAN); |
| 1576 | |
| 1577 | } else { |
| 1578 | uvm_pageactivate(pg); |
| 1579 | } |
| 1580 | mutex_exit(&uvm_pageqlock); |
| 1581 | |
| 1582 | if (wire_paging) { |
| 1583 | uvm_anon_dropswap(anon); |
| 1584 | } |
| 1585 | } |
| 1586 | |
| 1587 | /* |
| 1588 | * uvm_fault_lower: handle lower fault. |
| 1589 | * |
| 1590 | * 1. check uobj |
| 1591 | * 1.1. if null, ZFOD. |
| 1592 | * 1.2. if not null, look up unnmapped neighbor pages. |
| 1593 | * 2. for center page, check if promote. |
| 1594 | * 2.1. ZFOD always needs promotion. |
| 1595 | * 2.2. other uobjs, when entry is marked COW (usually MAP_PRIVATE vnode). |
| 1596 | * 3. if uobj is not ZFOD and page is not found, do i/o. |
| 1597 | * 4. dispatch either direct / promote fault. |
| 1598 | */ |
| 1599 | |
| 1600 | static int |
| 1601 | uvm_fault_lower( |
| 1602 | struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, |
| 1603 | struct vm_page **pages) |
| 1604 | { |
| 1605 | #ifdef DIAGNOSTIC |
| 1606 | struct vm_amap *amap = ufi->entry->aref.ar_amap; |
| 1607 | #endif |
| 1608 | struct uvm_object *uobj = ufi->entry->object.uvm_obj; |
| 1609 | struct vm_page *uobjpage; |
| 1610 | int error; |
| 1611 | UVMHIST_FUNC("uvm_fault_lower" ); UVMHIST_CALLED(maphist); |
| 1612 | |
| 1613 | /* |
| 1614 | * now, if the desired page is not shadowed by the amap and we have |
| 1615 | * a backing object that does not have a special fault routine, then |
| 1616 | * we ask (with pgo_get) the object for resident pages that we care |
| 1617 | * about and attempt to map them in. we do not let pgo_get block |
| 1618 | * (PGO_LOCKED). |
| 1619 | */ |
| 1620 | |
| 1621 | if (uobj == NULL) { |
| 1622 | /* zero fill; don't care neighbor pages */ |
| 1623 | uobjpage = NULL; |
| 1624 | } else { |
| 1625 | uvm_fault_lower_lookup(ufi, flt, pages); |
| 1626 | uobjpage = pages[flt->centeridx]; |
| 1627 | } |
| 1628 | |
| 1629 | /* |
| 1630 | * note that at this point we are done with any front or back pages. |
| 1631 | * we are now going to focus on the center page (i.e. the one we've |
| 1632 | * faulted on). if we have faulted on the upper (anon) layer |
| 1633 | * [i.e. case 1], then the anon we want is anons[centeridx] (we have |
| 1634 | * not touched it yet). if we have faulted on the bottom (uobj) |
| 1635 | * layer [i.e. case 2] and the page was both present and available, |
| 1636 | * then we've got a pointer to it as "uobjpage" and we've already |
| 1637 | * made it BUSY. |
| 1638 | */ |
| 1639 | |
| 1640 | /* |
| 1641 | * locked: |
| 1642 | * maps(read), amap(if there), uobj(if !null), uobjpage(if !null) |
| 1643 | */ |
| 1644 | KASSERT(amap == NULL || mutex_owned(amap->am_lock)); |
| 1645 | KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); |
| 1646 | KASSERT(uobjpage == NULL || (uobjpage->flags & PG_BUSY) != 0); |
| 1647 | |
| 1648 | /* |
| 1649 | * note that uobjpage can not be PGO_DONTCARE at this point. we now |
| 1650 | * set uobjpage to PGO_DONTCARE if we are doing a zero fill. if we |
| 1651 | * have a backing object, check and see if we are going to promote |
| 1652 | * the data up to an anon during the fault. |
| 1653 | */ |
| 1654 | |
| 1655 | if (uobj == NULL) { |
| 1656 | uobjpage = PGO_DONTCARE; |
| 1657 | flt->promote = true; /* always need anon here */ |
| 1658 | } else { |
| 1659 | KASSERT(uobjpage != PGO_DONTCARE); |
| 1660 | flt->promote = flt->cow_now && UVM_ET_ISCOPYONWRITE(ufi->entry); |
| 1661 | } |
| 1662 | UVMHIST_LOG(maphist, " case 2 fault: promote=%d, zfill=%d" , |
| 1663 | flt->promote, (uobj == NULL), 0,0); |
| 1664 | |
| 1665 | /* |
| 1666 | * if uobjpage is not null then we do not need to do I/O to get the |
| 1667 | * uobjpage. |
| 1668 | * |
| 1669 | * if uobjpage is null, then we need to unlock and ask the pager to |
| 1670 | * get the data for us. once we have the data, we need to reverify |
| 1671 | * the state the world. we are currently not holding any resources. |
| 1672 | */ |
| 1673 | |
| 1674 | if (uobjpage) { |
| 1675 | /* update rusage counters */ |
| 1676 | curlwp->l_ru.ru_minflt++; |
| 1677 | } else { |
| 1678 | error = uvm_fault_lower_io(ufi, flt, &uobj, &uobjpage); |
| 1679 | if (error != 0) |
| 1680 | return error; |
| 1681 | } |
| 1682 | |
| 1683 | /* |
| 1684 | * locked: |
| 1685 | * maps(read), amap(if !null), uobj(if !null), uobjpage(if uobj) |
| 1686 | */ |
| 1687 | KASSERT(amap == NULL || mutex_owned(amap->am_lock)); |
| 1688 | KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); |
| 1689 | KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0); |
| 1690 | |
| 1691 | /* |
| 1692 | * notes: |
| 1693 | * - at this point uobjpage can not be NULL |
| 1694 | * - at this point uobjpage can not be PG_RELEASED (since we checked |
| 1695 | * for it above) |
| 1696 | * - at this point uobjpage could be PG_WANTED (handle later) |
| 1697 | */ |
| 1698 | |
| 1699 | KASSERT(uobjpage != NULL); |
| 1700 | KASSERT(uobj == NULL || uobj == uobjpage->uobject); |
| 1701 | KASSERT(uobj == NULL || !UVM_OBJ_IS_CLEAN(uobjpage->uobject) || |
| 1702 | (uobjpage->flags & PG_CLEAN) != 0); |
| 1703 | |
| 1704 | if (!flt->promote) { |
| 1705 | error = uvm_fault_lower_direct(ufi, flt, uobj, uobjpage); |
| 1706 | } else { |
| 1707 | error = uvm_fault_lower_promote(ufi, flt, uobj, uobjpage); |
| 1708 | } |
| 1709 | return error; |
| 1710 | } |
| 1711 | |
| 1712 | /* |
| 1713 | * uvm_fault_lower_lookup: look up on-memory uobj pages. |
| 1714 | * |
| 1715 | * 1. get on-memory pages. |
| 1716 | * 2. if failed, give up (get only center page later). |
| 1717 | * 3. if succeeded, enter h/w mapping of neighbor pages. |
| 1718 | */ |
| 1719 | |
| 1720 | static void |
| 1721 | uvm_fault_lower_lookup( |
| 1722 | struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, |
| 1723 | struct vm_page **pages) |
| 1724 | { |
| 1725 | struct uvm_object *uobj = ufi->entry->object.uvm_obj; |
| 1726 | int lcv, gotpages; |
| 1727 | vaddr_t currva; |
| 1728 | UVMHIST_FUNC("uvm_fault_lower_lookup" ); UVMHIST_CALLED(maphist); |
| 1729 | |
| 1730 | mutex_enter(uobj->vmobjlock); |
| 1731 | /* Locked: maps(read), amap(if there), uobj */ |
| 1732 | |
| 1733 | uvmexp.fltlget++; |
| 1734 | gotpages = flt->npages; |
| 1735 | (void) uobj->pgops->pgo_get(uobj, |
| 1736 | ufi->entry->offset + flt->startva - ufi->entry->start, |
| 1737 | pages, &gotpages, flt->centeridx, |
| 1738 | flt->access_type & MASK(ufi->entry), ufi->entry->advice, PGO_LOCKED); |
| 1739 | |
| 1740 | KASSERT(mutex_owned(uobj->vmobjlock)); |
| 1741 | |
| 1742 | /* |
| 1743 | * check for pages to map, if we got any |
| 1744 | */ |
| 1745 | |
| 1746 | if (gotpages == 0) { |
| 1747 | pages[flt->centeridx] = NULL; |
| 1748 | return; |
| 1749 | } |
| 1750 | |
| 1751 | currva = flt->startva; |
| 1752 | for (lcv = 0; lcv < flt->npages; lcv++, currva += PAGE_SIZE) { |
| 1753 | struct vm_page *curpg; |
| 1754 | |
| 1755 | curpg = pages[lcv]; |
| 1756 | if (curpg == NULL || curpg == PGO_DONTCARE) { |
| 1757 | continue; |
| 1758 | } |
| 1759 | KASSERT(curpg->uobject == uobj); |
| 1760 | |
| 1761 | /* |
| 1762 | * if center page is resident and not PG_BUSY|PG_RELEASED |
| 1763 | * then pgo_get made it PG_BUSY for us and gave us a handle |
| 1764 | * to it. |
| 1765 | */ |
| 1766 | |
| 1767 | if (lcv == flt->centeridx) { |
| 1768 | UVMHIST_LOG(maphist, " got uobjpage " |
| 1769 | "(0x%x) with locked get" , |
| 1770 | curpg, 0,0,0); |
| 1771 | } else { |
| 1772 | bool readonly = (curpg->flags & PG_RDONLY) |
| 1773 | || (curpg->loan_count > 0) |
| 1774 | || UVM_OBJ_NEEDS_WRITEFAULT(curpg->uobject); |
| 1775 | |
| 1776 | uvm_fault_lower_neighbor(ufi, flt, |
| 1777 | currva, curpg, readonly); |
| 1778 | } |
| 1779 | } |
| 1780 | pmap_update(ufi->orig_map->pmap); |
| 1781 | } |
| 1782 | |
| 1783 | /* |
| 1784 | * uvm_fault_lower_neighbor: enter h/w mapping of lower neighbor page. |
| 1785 | */ |
| 1786 | |
| 1787 | static void |
| 1788 | uvm_fault_lower_neighbor( |
| 1789 | struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, |
| 1790 | vaddr_t currva, struct vm_page *pg, bool readonly) |
| 1791 | { |
| 1792 | UVMHIST_FUNC(__func__); UVMHIST_CALLED(maphist); |
| 1793 | |
| 1794 | /* locked: maps(read), amap(if there), uobj */ |
| 1795 | |
| 1796 | /* |
| 1797 | * calling pgo_get with PGO_LOCKED returns us pages which |
| 1798 | * are neither busy nor released, so we don't need to check |
| 1799 | * for this. we can just directly enter the pages. |
| 1800 | */ |
| 1801 | |
| 1802 | mutex_enter(&uvm_pageqlock); |
| 1803 | uvm_pageenqueue(pg); |
| 1804 | mutex_exit(&uvm_pageqlock); |
| 1805 | UVMHIST_LOG(maphist, |
| 1806 | " MAPPING: n obj: pm=%p, va=%#lx, pg=%p" , |
| 1807 | ufi->orig_map->pmap, currva, pg, 0); |
| 1808 | uvmexp.fltnomap++; |
| 1809 | |
| 1810 | /* |
| 1811 | * Since this page isn't the page that's actually faulting, |
| 1812 | * ignore pmap_enter() failures; it's not critical that we |
| 1813 | * enter these right now. |
| 1814 | * NOTE: page can't be PG_WANTED or PG_RELEASED because we've |
| 1815 | * held the lock the whole time we've had the handle. |
| 1816 | */ |
| 1817 | KASSERT((pg->flags & PG_PAGEOUT) == 0); |
| 1818 | KASSERT((pg->flags & PG_RELEASED) == 0); |
| 1819 | KASSERT((pg->flags & PG_WANTED) == 0); |
| 1820 | KASSERT(!UVM_OBJ_IS_CLEAN(pg->uobject) || (pg->flags & PG_CLEAN) != 0); |
| 1821 | pg->flags &= ~(PG_BUSY); |
| 1822 | UVM_PAGE_OWN(pg, NULL); |
| 1823 | |
| 1824 | KASSERT(mutex_owned(pg->uobject->vmobjlock)); |
| 1825 | (void) pmap_enter(ufi->orig_map->pmap, currva, |
| 1826 | VM_PAGE_TO_PHYS(pg), |
| 1827 | readonly ? (flt->enter_prot & ~VM_PROT_WRITE) : |
| 1828 | flt->enter_prot & MASK(ufi->entry), |
| 1829 | PMAP_CANFAIL | (flt->wire_mapping ? PMAP_WIRED : 0)); |
| 1830 | } |
| 1831 | |
| 1832 | /* |
| 1833 | * uvm_fault_lower_io: get lower page from backing store. |
| 1834 | * |
| 1835 | * 1. unlock everything, because i/o will block. |
| 1836 | * 2. call pgo_get. |
| 1837 | * 3. if failed, recover. |
| 1838 | * 4. if succeeded, relock everything and verify things. |
| 1839 | */ |
| 1840 | |
| 1841 | static int |
| 1842 | uvm_fault_lower_io( |
| 1843 | struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, |
| 1844 | struct uvm_object **ruobj, struct vm_page **ruobjpage) |
| 1845 | { |
| 1846 | struct vm_amap * const amap = ufi->entry->aref.ar_amap; |
| 1847 | struct uvm_object *uobj = *ruobj; |
| 1848 | struct vm_page *pg; |
| 1849 | bool locked; |
| 1850 | int gotpages; |
| 1851 | int error; |
| 1852 | voff_t uoff; |
| 1853 | UVMHIST_FUNC("uvm_fault_lower_io" ); UVMHIST_CALLED(maphist); |
| 1854 | |
| 1855 | /* update rusage counters */ |
| 1856 | curlwp->l_ru.ru_majflt++; |
| 1857 | |
| 1858 | /* Locked: maps(read), amap(if there), uobj */ |
| 1859 | uvmfault_unlockall(ufi, amap, NULL); |
| 1860 | |
| 1861 | /* Locked: uobj */ |
| 1862 | KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); |
| 1863 | |
| 1864 | uvmexp.fltget++; |
| 1865 | gotpages = 1; |
| 1866 | pg = NULL; |
| 1867 | uoff = (ufi->orig_rvaddr - ufi->entry->start) + ufi->entry->offset; |
| 1868 | error = uobj->pgops->pgo_get(uobj, uoff, &pg, &gotpages, |
| 1869 | 0, flt->access_type & MASK(ufi->entry), ufi->entry->advice, |
| 1870 | PGO_SYNCIO); |
| 1871 | /* locked: pg(if no error) */ |
| 1872 | |
| 1873 | /* |
| 1874 | * recover from I/O |
| 1875 | */ |
| 1876 | |
| 1877 | if (error) { |
| 1878 | if (error == EAGAIN) { |
| 1879 | UVMHIST_LOG(maphist, |
| 1880 | " pgo_get says TRY AGAIN!" ,0,0,0,0); |
| 1881 | kpause("fltagain2" , false, hz/2, NULL); |
| 1882 | return ERESTART; |
| 1883 | } |
| 1884 | |
| 1885 | #if 0 |
| 1886 | KASSERT(error != ERESTART); |
| 1887 | #else |
| 1888 | /* XXXUEBS don't re-fault? */ |
| 1889 | if (error == ERESTART) |
| 1890 | error = EIO; |
| 1891 | #endif |
| 1892 | |
| 1893 | UVMHIST_LOG(maphist, "<- pgo_get failed (code %d)" , |
| 1894 | error, 0,0,0); |
| 1895 | return error; |
| 1896 | } |
| 1897 | |
| 1898 | /* |
| 1899 | * re-verify the state of the world by first trying to relock |
| 1900 | * the maps. always relock the object. |
| 1901 | */ |
| 1902 | |
| 1903 | locked = uvmfault_relock(ufi); |
| 1904 | if (locked && amap) |
| 1905 | amap_lock(amap); |
| 1906 | |
| 1907 | /* might be changed */ |
| 1908 | uobj = pg->uobject; |
| 1909 | |
| 1910 | mutex_enter(uobj->vmobjlock); |
| 1911 | KASSERT((pg->flags & PG_BUSY) != 0); |
| 1912 | |
| 1913 | mutex_enter(&uvm_pageqlock); |
| 1914 | uvm_pageactivate(pg); |
| 1915 | mutex_exit(&uvm_pageqlock); |
| 1916 | |
| 1917 | /* locked(locked): maps(read), amap(if !null), uobj, pg */ |
| 1918 | /* locked(!locked): uobj, pg */ |
| 1919 | |
| 1920 | /* |
| 1921 | * verify that the page has not be released and re-verify |
| 1922 | * that amap slot is still free. if there is a problem, |
| 1923 | * we unlock and clean up. |
| 1924 | */ |
| 1925 | |
| 1926 | if ((pg->flags & PG_RELEASED) != 0 || |
| 1927 | (locked && amap && amap_lookup(&ufi->entry->aref, |
| 1928 | ufi->orig_rvaddr - ufi->entry->start))) { |
| 1929 | if (locked) |
| 1930 | uvmfault_unlockall(ufi, amap, NULL); |
| 1931 | locked = false; |
| 1932 | } |
| 1933 | |
| 1934 | /* |
| 1935 | * didn't get the lock? release the page and retry. |
| 1936 | */ |
| 1937 | |
| 1938 | if (locked == false) { |
| 1939 | UVMHIST_LOG(maphist, |
| 1940 | " wasn't able to relock after fault: retry" , |
| 1941 | 0,0,0,0); |
| 1942 | if (pg->flags & PG_WANTED) { |
| 1943 | wakeup(pg); |
| 1944 | } |
| 1945 | if ((pg->flags & PG_RELEASED) == 0) { |
| 1946 | pg->flags &= ~(PG_BUSY | PG_WANTED); |
| 1947 | UVM_PAGE_OWN(pg, NULL); |
| 1948 | } else { |
| 1949 | uvmexp.fltpgrele++; |
| 1950 | uvm_pagefree(pg); |
| 1951 | } |
| 1952 | mutex_exit(uobj->vmobjlock); |
| 1953 | return ERESTART; |
| 1954 | } |
| 1955 | |
| 1956 | /* |
| 1957 | * we have the data in pg which is busy and |
| 1958 | * not released. we are holding object lock (so the page |
| 1959 | * can't be released on us). |
| 1960 | */ |
| 1961 | |
| 1962 | /* locked: maps(read), amap(if !null), uobj, pg */ |
| 1963 | |
| 1964 | *ruobj = uobj; |
| 1965 | *ruobjpage = pg; |
| 1966 | return 0; |
| 1967 | } |
| 1968 | |
| 1969 | /* |
| 1970 | * uvm_fault_lower_direct: fault lower center page |
| 1971 | * |
| 1972 | * 1. adjust flt->enter_prot. |
| 1973 | * 2. if page is loaned, resolve. |
| 1974 | */ |
| 1975 | |
| 1976 | int |
| 1977 | uvm_fault_lower_direct( |
| 1978 | struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, |
| 1979 | struct uvm_object *uobj, struct vm_page *uobjpage) |
| 1980 | { |
| 1981 | struct vm_page *pg; |
| 1982 | UVMHIST_FUNC("uvm_fault_lower_direct" ); UVMHIST_CALLED(maphist); |
| 1983 | |
| 1984 | /* |
| 1985 | * we are not promoting. if the mapping is COW ensure that we |
| 1986 | * don't give more access than we should (e.g. when doing a read |
| 1987 | * fault on a COPYONWRITE mapping we want to map the COW page in |
| 1988 | * R/O even though the entry protection could be R/W). |
| 1989 | * |
| 1990 | * set "pg" to the page we want to map in (uobjpage, usually) |
| 1991 | */ |
| 1992 | |
| 1993 | uvmexp.flt_obj++; |
| 1994 | if (UVM_ET_ISCOPYONWRITE(ufi->entry) || |
| 1995 | UVM_OBJ_NEEDS_WRITEFAULT(uobjpage->uobject)) |
| 1996 | flt->enter_prot &= ~VM_PROT_WRITE; |
| 1997 | pg = uobjpage; /* map in the actual object */ |
| 1998 | |
| 1999 | KASSERT(uobjpage != PGO_DONTCARE); |
| 2000 | |
| 2001 | /* |
| 2002 | * we are faulting directly on the page. be careful |
| 2003 | * about writing to loaned pages... |
| 2004 | */ |
| 2005 | |
| 2006 | if (uobjpage->loan_count) { |
| 2007 | uvm_fault_lower_direct_loan(ufi, flt, uobj, &pg, &uobjpage); |
| 2008 | } |
| 2009 | KASSERT(pg == uobjpage); |
| 2010 | |
| 2011 | KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0); |
| 2012 | return uvm_fault_lower_enter(ufi, flt, uobj, NULL, pg); |
| 2013 | } |
| 2014 | |
| 2015 | /* |
| 2016 | * uvm_fault_lower_direct_loan: resolve loaned page. |
| 2017 | * |
| 2018 | * 1. if not cow'ing, adjust flt->enter_prot. |
| 2019 | * 2. if cow'ing, break loan. |
| 2020 | */ |
| 2021 | |
| 2022 | static int |
| 2023 | uvm_fault_lower_direct_loan( |
| 2024 | struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, |
| 2025 | struct uvm_object *uobj, struct vm_page **rpg, |
| 2026 | struct vm_page **ruobjpage) |
| 2027 | { |
| 2028 | struct vm_amap * const amap = ufi->entry->aref.ar_amap; |
| 2029 | struct vm_page *pg; |
| 2030 | struct vm_page *uobjpage = *ruobjpage; |
| 2031 | UVMHIST_FUNC("uvm_fault_lower_direct_loan" ); UVMHIST_CALLED(maphist); |
| 2032 | |
| 2033 | if (!flt->cow_now) { |
| 2034 | /* read fault: cap the protection at readonly */ |
| 2035 | /* cap! */ |
| 2036 | flt->enter_prot = flt->enter_prot & ~VM_PROT_WRITE; |
| 2037 | } else { |
| 2038 | /* write fault: must break the loan here */ |
| 2039 | |
| 2040 | pg = uvm_loanbreak(uobjpage); |
| 2041 | if (pg == NULL) { |
| 2042 | |
| 2043 | /* |
| 2044 | * drop ownership of page, it can't be released |
| 2045 | */ |
| 2046 | |
| 2047 | if (uobjpage->flags & PG_WANTED) |
| 2048 | wakeup(uobjpage); |
| 2049 | uobjpage->flags &= ~(PG_BUSY|PG_WANTED); |
| 2050 | UVM_PAGE_OWN(uobjpage, NULL); |
| 2051 | |
| 2052 | uvmfault_unlockall(ufi, amap, uobj); |
| 2053 | UVMHIST_LOG(maphist, |
| 2054 | " out of RAM breaking loan, waiting" , |
| 2055 | 0,0,0,0); |
| 2056 | uvmexp.fltnoram++; |
| 2057 | uvm_wait("flt_noram4" ); |
| 2058 | return ERESTART; |
| 2059 | } |
| 2060 | *rpg = pg; |
| 2061 | *ruobjpage = pg; |
| 2062 | } |
| 2063 | return 0; |
| 2064 | } |
| 2065 | |
| 2066 | /* |
| 2067 | * uvm_fault_lower_promote: promote lower page. |
| 2068 | * |
| 2069 | * 1. call uvmfault_promote. |
| 2070 | * 2. fill in data. |
| 2071 | * 3. if not ZFOD, dispose old page. |
| 2072 | */ |
| 2073 | |
| 2074 | int |
| 2075 | uvm_fault_lower_promote( |
| 2076 | struct uvm_faultinfo *ufi, struct uvm_faultctx *flt, |
| 2077 | struct uvm_object *uobj, struct vm_page *uobjpage) |
| 2078 | { |
| 2079 | struct vm_amap * const amap = ufi->entry->aref.ar_amap; |
| 2080 | struct vm_anon *anon; |
| 2081 | struct vm_page *pg; |
| 2082 | int error; |
| 2083 | UVMHIST_FUNC("uvm_fault_lower_promote" ); UVMHIST_CALLED(maphist); |
| 2084 | |
| 2085 | KASSERT(amap != NULL); |
| 2086 | |
| 2087 | /* |
| 2088 | * If we are going to promote the data to an anon we |
| 2089 | * allocate a blank anon here and plug it into our amap. |
| 2090 | */ |
| 2091 | error = uvmfault_promote(ufi, NULL, uobjpage, |
| 2092 | &anon, &flt->anon_spare); |
| 2093 | switch (error) { |
| 2094 | case 0: |
| 2095 | break; |
| 2096 | case ERESTART: |
| 2097 | return ERESTART; |
| 2098 | default: |
| 2099 | return error; |
| 2100 | } |
| 2101 | |
| 2102 | pg = anon->an_page; |
| 2103 | |
| 2104 | /* |
| 2105 | * Fill in the data. |
| 2106 | */ |
| 2107 | KASSERT(uobj == NULL || (uobjpage->flags & PG_BUSY) != 0); |
| 2108 | |
| 2109 | if (uobjpage != PGO_DONTCARE) { |
| 2110 | uvmexp.flt_prcopy++; |
| 2111 | |
| 2112 | /* |
| 2113 | * promote to shared amap? make sure all sharing |
| 2114 | * procs see it |
| 2115 | */ |
| 2116 | |
| 2117 | if ((amap_flags(amap) & AMAP_SHARED) != 0) { |
| 2118 | pmap_page_protect(uobjpage, VM_PROT_NONE); |
| 2119 | /* |
| 2120 | * XXX: PAGE MIGHT BE WIRED! |
| 2121 | */ |
| 2122 | } |
| 2123 | |
| 2124 | /* |
| 2125 | * dispose of uobjpage. it can't be PG_RELEASED |
| 2126 | * since we still hold the object lock. |
| 2127 | */ |
| 2128 | |
| 2129 | if (uobjpage->flags & PG_WANTED) { |
| 2130 | /* still have the obj lock */ |
| 2131 | wakeup(uobjpage); |
| 2132 | } |
| 2133 | uobjpage->flags &= ~(PG_BUSY|PG_WANTED); |
| 2134 | UVM_PAGE_OWN(uobjpage, NULL); |
| 2135 | |
| 2136 | UVMHIST_LOG(maphist, |
| 2137 | " promote uobjpage 0x%x to anon/page 0x%x/0x%x" , |
| 2138 | uobjpage, anon, pg, 0); |
| 2139 | |
| 2140 | } else { |
| 2141 | uvmexp.flt_przero++; |
| 2142 | |
| 2143 | /* |
| 2144 | * Page is zero'd and marked dirty by |
| 2145 | * uvmfault_promote(). |
| 2146 | */ |
| 2147 | |
| 2148 | UVMHIST_LOG(maphist," zero fill anon/page 0x%x/0%x" , |
| 2149 | anon, pg, 0, 0); |
| 2150 | } |
| 2151 | |
| 2152 | return uvm_fault_lower_enter(ufi, flt, uobj, anon, pg); |
| 2153 | } |
| 2154 | |
| 2155 | /* |
| 2156 | * uvm_fault_lower_enter: enter h/w mapping of lower page or anon page promoted |
| 2157 | * from the lower page. |
| 2158 | */ |
| 2159 | |
| 2160 | int |
| 2161 | uvm_fault_lower_enter( |
| 2162 | struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, |
| 2163 | struct uvm_object *uobj, |
| 2164 | struct vm_anon *anon, struct vm_page *pg) |
| 2165 | { |
| 2166 | struct vm_amap * const amap = ufi->entry->aref.ar_amap; |
| 2167 | int error; |
| 2168 | UVMHIST_FUNC("uvm_fault_lower_enter" ); UVMHIST_CALLED(maphist); |
| 2169 | |
| 2170 | /* |
| 2171 | * Locked: |
| 2172 | * |
| 2173 | * maps(read), amap(if !null), uobj(if !null), |
| 2174 | * anon(if !null), pg(if anon), unlock_uobj(if !null) |
| 2175 | * |
| 2176 | * Note: pg is either the uobjpage or the new page in the new anon. |
| 2177 | */ |
| 2178 | KASSERT(amap == NULL || mutex_owned(amap->am_lock)); |
| 2179 | KASSERT(uobj == NULL || mutex_owned(uobj->vmobjlock)); |
| 2180 | KASSERT(anon == NULL || anon->an_lock == amap->am_lock); |
| 2181 | KASSERT((pg->flags & PG_BUSY) != 0); |
| 2182 | |
| 2183 | /* |
| 2184 | * all resources are present. we can now map it in and free our |
| 2185 | * resources. |
| 2186 | */ |
| 2187 | |
| 2188 | UVMHIST_LOG(maphist, |
| 2189 | " MAPPING: case2: pm=%p, va=%#lx, pg=%#x, promote=%d" , |
| 2190 | ufi->orig_map->pmap, ufi->orig_rvaddr, pg, flt->promote); |
| 2191 | KASSERT((flt->access_type & VM_PROT_WRITE) == 0 || |
| 2192 | (pg->flags & PG_RDONLY) == 0); |
| 2193 | if (pmap_enter(ufi->orig_map->pmap, ufi->orig_rvaddr, |
| 2194 | VM_PAGE_TO_PHYS(pg), |
| 2195 | (pg->flags & PG_RDONLY) != 0 ? |
| 2196 | flt->enter_prot & ~VM_PROT_WRITE : flt->enter_prot, |
| 2197 | flt->access_type | PMAP_CANFAIL | |
| 2198 | (flt->wire_mapping ? PMAP_WIRED : 0)) != 0) { |
| 2199 | |
| 2200 | /* |
| 2201 | * No need to undo what we did; we can simply think of |
| 2202 | * this as the pmap throwing away the mapping information. |
| 2203 | * |
| 2204 | * We do, however, have to go through the ReFault path, |
| 2205 | * as the map may change while we're asleep. |
| 2206 | */ |
| 2207 | |
| 2208 | /* |
| 2209 | * ensure that the page is queued in the case that |
| 2210 | * we just promoted the page. |
| 2211 | */ |
| 2212 | |
| 2213 | mutex_enter(&uvm_pageqlock); |
| 2214 | uvm_pageenqueue(pg); |
| 2215 | mutex_exit(&uvm_pageqlock); |
| 2216 | |
| 2217 | if (pg->flags & PG_WANTED) |
| 2218 | wakeup(pg); |
| 2219 | |
| 2220 | /* |
| 2221 | * note that pg can't be PG_RELEASED since we did not drop |
| 2222 | * the object lock since the last time we checked. |
| 2223 | */ |
| 2224 | KASSERT((pg->flags & PG_RELEASED) == 0); |
| 2225 | |
| 2226 | pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); |
| 2227 | UVM_PAGE_OWN(pg, NULL); |
| 2228 | |
| 2229 | uvmfault_unlockall(ufi, amap, uobj); |
| 2230 | if (!uvm_reclaimable()) { |
| 2231 | UVMHIST_LOG(maphist, |
| 2232 | "<- failed. out of VM" ,0,0,0,0); |
| 2233 | /* XXX instrumentation */ |
| 2234 | error = ENOMEM; |
| 2235 | return error; |
| 2236 | } |
| 2237 | /* XXX instrumentation */ |
| 2238 | uvm_wait("flt_pmfail2" ); |
| 2239 | return ERESTART; |
| 2240 | } |
| 2241 | |
| 2242 | uvm_fault_lower_done(ufi, flt, uobj, pg); |
| 2243 | |
| 2244 | /* |
| 2245 | * note that pg can't be PG_RELEASED since we did not drop the object |
| 2246 | * lock since the last time we checked. |
| 2247 | */ |
| 2248 | KASSERT((pg->flags & PG_RELEASED) == 0); |
| 2249 | if (pg->flags & PG_WANTED) |
| 2250 | wakeup(pg); |
| 2251 | pg->flags &= ~(PG_BUSY|PG_FAKE|PG_WANTED); |
| 2252 | UVM_PAGE_OWN(pg, NULL); |
| 2253 | |
| 2254 | pmap_update(ufi->orig_map->pmap); |
| 2255 | uvmfault_unlockall(ufi, amap, uobj); |
| 2256 | |
| 2257 | UVMHIST_LOG(maphist, "<- done (SUCCESS!)" ,0,0,0,0); |
| 2258 | return 0; |
| 2259 | } |
| 2260 | |
| 2261 | /* |
| 2262 | * uvm_fault_lower_done: queue lower center page. |
| 2263 | */ |
| 2264 | |
| 2265 | void |
| 2266 | uvm_fault_lower_done( |
| 2267 | struct uvm_faultinfo *ufi, const struct uvm_faultctx *flt, |
| 2268 | struct uvm_object *uobj, struct vm_page *pg) |
| 2269 | { |
| 2270 | bool dropswap = false; |
| 2271 | |
| 2272 | UVMHIST_FUNC("uvm_fault_lower_done" ); UVMHIST_CALLED(maphist); |
| 2273 | |
| 2274 | mutex_enter(&uvm_pageqlock); |
| 2275 | if (flt->wire_paging) { |
| 2276 | uvm_pagewire(pg); |
| 2277 | if (pg->pqflags & PQ_AOBJ) { |
| 2278 | |
| 2279 | /* |
| 2280 | * since the now-wired page cannot be paged out, |
| 2281 | * release its swap resources for others to use. |
| 2282 | * since an aobj page with no swap cannot be PG_CLEAN, |
| 2283 | * clear its clean flag now. |
| 2284 | */ |
| 2285 | |
| 2286 | KASSERT(uobj != NULL); |
| 2287 | pg->flags &= ~(PG_CLEAN); |
| 2288 | dropswap = true; |
| 2289 | } |
| 2290 | } else { |
| 2291 | uvm_pageactivate(pg); |
| 2292 | } |
| 2293 | mutex_exit(&uvm_pageqlock); |
| 2294 | |
| 2295 | if (dropswap) { |
| 2296 | uao_dropswap(uobj, pg->offset >> PAGE_SHIFT); |
| 2297 | } |
| 2298 | } |
| 2299 | |
| 2300 | |
| 2301 | /* |
| 2302 | * uvm_fault_wire: wire down a range of virtual addresses in a map. |
| 2303 | * |
| 2304 | * => map may be read-locked by caller, but MUST NOT be write-locked. |
| 2305 | * => if map is read-locked, any operations which may cause map to |
| 2306 | * be write-locked in uvm_fault() must be taken care of by |
| 2307 | * the caller. See uvm_map_pageable(). |
| 2308 | */ |
| 2309 | |
| 2310 | int |
| 2311 | uvm_fault_wire(struct vm_map *map, vaddr_t start, vaddr_t end, |
| 2312 | vm_prot_t access_type, int maxprot) |
| 2313 | { |
| 2314 | vaddr_t va; |
| 2315 | int error; |
| 2316 | |
| 2317 | /* |
| 2318 | * now fault it in a page at a time. if the fault fails then we have |
| 2319 | * to undo what we have done. note that in uvm_fault VM_PROT_NONE |
| 2320 | * is replaced with the max protection if fault_type is VM_FAULT_WIRE. |
| 2321 | */ |
| 2322 | |
| 2323 | /* |
| 2324 | * XXX work around overflowing a vaddr_t. this prevents us from |
| 2325 | * wiring the last page in the address space, though. |
| 2326 | */ |
| 2327 | if (start > end) { |
| 2328 | return EFAULT; |
| 2329 | } |
| 2330 | |
| 2331 | for (va = start; va < end; va += PAGE_SIZE) { |
| 2332 | error = uvm_fault_internal(map, va, access_type, |
| 2333 | (maxprot ? UVM_FAULT_MAXPROT : 0) | UVM_FAULT_WIRE); |
| 2334 | if (error) { |
| 2335 | if (va != start) { |
| 2336 | uvm_fault_unwire(map, start, va); |
| 2337 | } |
| 2338 | return error; |
| 2339 | } |
| 2340 | } |
| 2341 | return 0; |
| 2342 | } |
| 2343 | |
| 2344 | /* |
| 2345 | * uvm_fault_unwire(): unwire range of virtual space. |
| 2346 | */ |
| 2347 | |
| 2348 | void |
| 2349 | uvm_fault_unwire(struct vm_map *map, vaddr_t start, vaddr_t end) |
| 2350 | { |
| 2351 | vm_map_lock_read(map); |
| 2352 | uvm_fault_unwire_locked(map, start, end); |
| 2353 | vm_map_unlock_read(map); |
| 2354 | } |
| 2355 | |
| 2356 | /* |
| 2357 | * uvm_fault_unwire_locked(): the guts of uvm_fault_unwire(). |
| 2358 | * |
| 2359 | * => map must be at least read-locked. |
| 2360 | */ |
| 2361 | |
| 2362 | void |
| 2363 | uvm_fault_unwire_locked(struct vm_map *map, vaddr_t start, vaddr_t end) |
| 2364 | { |
| 2365 | struct vm_map_entry *entry, *oentry; |
| 2366 | pmap_t pmap = vm_map_pmap(map); |
| 2367 | vaddr_t va; |
| 2368 | paddr_t pa; |
| 2369 | struct vm_page *pg; |
| 2370 | |
| 2371 | /* |
| 2372 | * we assume that the area we are unwiring has actually been wired |
| 2373 | * in the first place. this means that we should be able to extract |
| 2374 | * the PAs from the pmap. we also lock out the page daemon so that |
| 2375 | * we can call uvm_pageunwire. |
| 2376 | */ |
| 2377 | |
| 2378 | /* |
| 2379 | * find the beginning map entry for the region. |
| 2380 | */ |
| 2381 | |
| 2382 | KASSERT(start >= vm_map_min(map) && end <= vm_map_max(map)); |
| 2383 | if (uvm_map_lookup_entry(map, start, &entry) == false) |
| 2384 | panic("uvm_fault_unwire_locked: address not in map" ); |
| 2385 | |
| 2386 | oentry = NULL; |
| 2387 | for (va = start; va < end; va += PAGE_SIZE) { |
| 2388 | if (pmap_extract(pmap, va, &pa) == false) |
| 2389 | continue; |
| 2390 | |
| 2391 | /* |
| 2392 | * find the map entry for the current address. |
| 2393 | */ |
| 2394 | |
| 2395 | KASSERT(va >= entry->start); |
| 2396 | while (va >= entry->end) { |
| 2397 | KASSERT(entry->next != &map->header && |
| 2398 | entry->next->start <= entry->end); |
| 2399 | entry = entry->next; |
| 2400 | } |
| 2401 | |
| 2402 | /* |
| 2403 | * lock it. |
| 2404 | */ |
| 2405 | |
| 2406 | if (entry != oentry) { |
| 2407 | if (oentry != NULL) { |
| 2408 | mutex_exit(&uvm_pageqlock); |
| 2409 | uvm_map_unlock_entry(oentry); |
| 2410 | } |
| 2411 | uvm_map_lock_entry(entry); |
| 2412 | mutex_enter(&uvm_pageqlock); |
| 2413 | oentry = entry; |
| 2414 | } |
| 2415 | |
| 2416 | /* |
| 2417 | * if the entry is no longer wired, tell the pmap. |
| 2418 | */ |
| 2419 | |
| 2420 | if (VM_MAPENT_ISWIRED(entry) == 0) |
| 2421 | pmap_unwire(pmap, va); |
| 2422 | |
| 2423 | pg = PHYS_TO_VM_PAGE(pa); |
| 2424 | if (pg) |
| 2425 | uvm_pageunwire(pg); |
| 2426 | } |
| 2427 | |
| 2428 | if (oentry != NULL) { |
| 2429 | mutex_exit(&uvm_pageqlock); |
| 2430 | uvm_map_unlock_entry(entry); |
| 2431 | } |
| 2432 | } |
| 2433 | |