1 /* $NetBSD: uvm_aobj.c,v 1.15 1998/10/18 23:49:59 chs Exp $ */ 2 3 /* 4 * XXXCDC: "ROUGH DRAFT" QUALITY UVM PRE-RELEASE FILE! 5 * >>>USE AT YOUR OWN RISK, WORK IS NOT FINISHED<<< 6 */ 7 /* 8 * Copyright (c) 1998 Chuck Silvers, Charles D. Cranor and 9 * Washington University. 10 * All rights reserved. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by Charles D. Cranor and 23 * Washington University. 24 * 4. The name of the author may not be used to endorse or promote products 25 * derived from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 * 38 * from: Id: uvm_aobj.c,v 1.1.2.5 1998/02/06 05:14:38 chs Exp 39 */ 40 /* 41 * uvm_aobj.c: anonymous memory uvm_object pager 42 * 43 * author: Chuck Silvers <chuq@chuq.com> 44 * started: Jan-1998 45 * 46 * - design mostly from Chuck Cranor 47 */ 48 49 50 51 #include "opt_uvmhist.h" 52 53 #include <sys/param.h> 54 #include <sys/systm.h> 55 #include <sys/proc.h> 56 #include <sys/malloc.h> 57 #include <sys/pool.h> 58 59 #include <vm/vm.h> 60 #include <vm/vm_page.h> 61 #include <vm/vm_kern.h> 62 63 #include <uvm/uvm.h> 64 65 /* 66 * an aobj manages anonymous-memory backed uvm_objects. in addition 67 * to keeping the list of resident pages, it also keeps a list of 68 * allocated swap blocks. depending on the size of the aobj this list 69 * of allocated swap blocks is either stored in an array (small objects) 70 * or in a hash table (large objects). 71 */ 72 73 /* 74 * local structures 75 */ 76 77 /* 78 * for hash tables, we break the address space of the aobj into blocks 79 * of UAO_SWHASH_CLUSTER_SIZE pages. we require the cluster size to 80 * be a power of two. 81 */ 82 83 #define UAO_SWHASH_CLUSTER_SHIFT 4 84 #define UAO_SWHASH_CLUSTER_SIZE (1 << UAO_SWHASH_CLUSTER_SHIFT) 85 86 /* get the "tag" for this page index */ 87 #define UAO_SWHASH_ELT_TAG(PAGEIDX) \ 88 ((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT) 89 90 /* given an ELT and a page index, find the swap slot */ 91 #define UAO_SWHASH_ELT_PAGESLOT(ELT, PAGEIDX) \ 92 ((ELT)->slots[(PAGEIDX) & (UAO_SWHASH_CLUSTER_SIZE - 1)]) 93 94 /* given an ELT, return its pageidx base */ 95 #define UAO_SWHASH_ELT_PAGEIDX_BASE(ELT) \ 96 ((ELT)->tag << UAO_SWHASH_CLUSTER_SHIFT) 97 98 /* 99 * the swhash hash function 100 */ 101 #define UAO_SWHASH_HASH(AOBJ, PAGEIDX) \ 102 (&(AOBJ)->u_swhash[(((PAGEIDX) >> UAO_SWHASH_CLUSTER_SHIFT) \ 103 & (AOBJ)->u_swhashmask)]) 104 105 /* 106 * the swhash threshhold determines if we will use an array or a 107 * hash table to store the list of allocated swap blocks. 108 */ 109 110 #define UAO_SWHASH_THRESHOLD (UAO_SWHASH_CLUSTER_SIZE * 4) 111 #define UAO_USES_SWHASH(AOBJ) \ 112 ((AOBJ)->u_pages > UAO_SWHASH_THRESHOLD) /* use hash? */ 113 114 /* 115 * the number of buckets in a swhash, with an upper bound 116 */ 117 #define UAO_SWHASH_MAXBUCKETS 256 118 #define UAO_SWHASH_BUCKETS(AOBJ) \ 119 (min((AOBJ)->u_pages >> UAO_SWHASH_CLUSTER_SHIFT, \ 120 UAO_SWHASH_MAXBUCKETS)) 121 122 123 /* 124 * uao_swhash_elt: when a hash table is being used, this structure defines 125 * the format of an entry in the bucket list. 126 */ 127 128 struct uao_swhash_elt { 129 LIST_ENTRY(uao_swhash_elt) list; /* the hash list */ 130 vaddr_t tag; /* our 'tag' */ 131 int count; /* our number of active slots */ 132 int slots[UAO_SWHASH_CLUSTER_SIZE]; /* the slots */ 133 }; 134 135 /* 136 * uao_swhash: the swap hash table structure 137 */ 138 139 LIST_HEAD(uao_swhash, uao_swhash_elt); 140 141 /* 142 * uao_swhash_elt_pool: pool of uao_swhash_elt structures 143 */ 144 145 struct pool uao_swhash_elt_pool; 146 147 /* 148 * uvm_aobj: the actual anon-backed uvm_object 149 * 150 * => the uvm_object is at the top of the structure, this allows 151 * (struct uvm_device *) == (struct uvm_object *) 152 * => only one of u_swslots and u_swhash is used in any given aobj 153 */ 154 155 struct uvm_aobj { 156 struct uvm_object u_obj; /* has: lock, pgops, memq, #pages, #refs */ 157 int u_pages; /* number of pages in entire object */ 158 int u_flags; /* the flags (see uvm_aobj.h) */ 159 int *u_swslots; /* array of offset->swapslot mappings */ 160 /* 161 * hashtable of offset->swapslot mappings 162 * (u_swhash is an array of bucket heads) 163 */ 164 struct uao_swhash *u_swhash; 165 u_long u_swhashmask; /* mask for hashtable */ 166 LIST_ENTRY(uvm_aobj) u_list; /* global list of aobjs */ 167 }; 168 169 /* 170 * uvm_aobj_pool: pool of uvm_aobj structures 171 */ 172 173 struct pool uvm_aobj_pool; 174 175 /* 176 * local functions 177 */ 178 179 static void uao_init __P((void)); 180 static struct uao_swhash_elt *uao_find_swhash_elt __P((struct uvm_aobj *, 181 int, boolean_t)); 182 static int uao_find_swslot __P((struct uvm_aobj *, 183 int)); 184 static boolean_t uao_flush __P((struct uvm_object *, 185 vaddr_t, vaddr_t, 186 int)); 187 static void uao_free __P((struct uvm_aobj *)); 188 static int uao_get __P((struct uvm_object *, vaddr_t, 189 vm_page_t *, int *, int, 190 vm_prot_t, int, int)); 191 static boolean_t uao_releasepg __P((struct vm_page *, 192 struct vm_page **)); 193 194 195 196 /* 197 * aobj_pager 198 * 199 * note that some functions (e.g. put) are handled elsewhere 200 */ 201 202 struct uvm_pagerops aobj_pager = { 203 uao_init, /* init */ 204 NULL, /* attach */ 205 uao_reference, /* reference */ 206 uao_detach, /* detach */ 207 NULL, /* fault */ 208 uao_flush, /* flush */ 209 uao_get, /* get */ 210 NULL, /* asyncget */ 211 NULL, /* put (done by pagedaemon) */ 212 NULL, /* cluster */ 213 NULL, /* mk_pcluster */ 214 uvm_shareprot, /* shareprot */ 215 NULL, /* aiodone */ 216 uao_releasepg /* releasepg */ 217 }; 218 219 /* 220 * uao_list: global list of active aobjs, locked by uao_list_lock 221 */ 222 223 static LIST_HEAD(aobjlist, uvm_aobj) uao_list; 224 static simple_lock_data_t uao_list_lock; 225 226 227 /* 228 * functions 229 */ 230 231 /* 232 * hash table/array related functions 233 */ 234 235 /* 236 * uao_find_swhash_elt: find (or create) a hash table entry for a page 237 * offset. 238 * 239 * => the object should be locked by the caller 240 */ 241 242 static struct uao_swhash_elt * 243 uao_find_swhash_elt(aobj, pageidx, create) 244 struct uvm_aobj *aobj; 245 int pageidx; 246 boolean_t create; 247 { 248 struct uao_swhash *swhash; 249 struct uao_swhash_elt *elt; 250 int page_tag; 251 252 swhash = UAO_SWHASH_HASH(aobj, pageidx); /* first hash to get bucket */ 253 page_tag = UAO_SWHASH_ELT_TAG(pageidx); /* tag to search for */ 254 255 /* 256 * now search the bucket for the requested tag 257 */ 258 for (elt = swhash->lh_first; elt != NULL; elt = elt->list.le_next) { 259 if (elt->tag == page_tag) 260 return(elt); 261 } 262 263 /* fail now if we are not allowed to create a new entry in the bucket */ 264 if (!create) 265 return NULL; 266 267 268 /* 269 * allocate a new entry for the bucket and init/insert it in 270 */ 271 elt = pool_get(&uao_swhash_elt_pool, PR_WAITOK); 272 LIST_INSERT_HEAD(swhash, elt, list); 273 elt->tag = page_tag; 274 elt->count = 0; 275 memset(elt->slots, 0, sizeof(elt->slots)); 276 277 return(elt); 278 } 279 280 /* 281 * uao_find_swslot: find the swap slot number for an aobj/pageidx 282 * 283 * => object must be locked by caller 284 */ 285 __inline static int 286 uao_find_swslot(aobj, pageidx) 287 struct uvm_aobj *aobj; 288 int pageidx; 289 { 290 291 /* 292 * if noswap flag is set, then we never return a slot 293 */ 294 295 if (aobj->u_flags & UAO_FLAG_NOSWAP) 296 return(0); 297 298 /* 299 * if hashing, look in hash table. 300 */ 301 302 if (UAO_USES_SWHASH(aobj)) { 303 struct uao_swhash_elt *elt = 304 uao_find_swhash_elt(aobj, pageidx, FALSE); 305 306 if (elt) 307 return(UAO_SWHASH_ELT_PAGESLOT(elt, pageidx)); 308 else 309 return(NULL); 310 } 311 312 /* 313 * otherwise, look in the array 314 */ 315 return(aobj->u_swslots[pageidx]); 316 } 317 318 /* 319 * uao_set_swslot: set the swap slot for a page in an aobj. 320 * 321 * => setting a slot to zero frees the slot 322 * => object must be locked by caller 323 */ 324 int 325 uao_set_swslot(uobj, pageidx, slot) 326 struct uvm_object *uobj; 327 int pageidx, slot; 328 { 329 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 330 int oldslot; 331 UVMHIST_FUNC("uao_set_swslot"); UVMHIST_CALLED(pdhist); 332 UVMHIST_LOG(pdhist, "aobj %p pageidx %d slot %d", 333 aobj, pageidx, slot, 0); 334 335 /* 336 * if noswap flag is set, then we can't set a slot 337 */ 338 339 if (aobj->u_flags & UAO_FLAG_NOSWAP) { 340 341 if (slot == 0) 342 return(0); /* a clear is ok */ 343 344 /* but a set is not */ 345 printf("uao_set_swslot: uobj = %p\n", uobj); 346 panic("uao_set_swslot: attempt to set a slot on a NOSWAP object"); 347 } 348 349 /* 350 * are we using a hash table? if so, add it in the hash. 351 */ 352 353 if (UAO_USES_SWHASH(aobj)) { 354 /* 355 * Avoid allocating an entry just to free it again if 356 * the page had not swap slot in the first place, and 357 * we are freeing. 358 */ 359 struct uao_swhash_elt *elt = 360 uao_find_swhash_elt(aobj, pageidx, slot ? TRUE : FALSE); 361 if (elt == NULL) { 362 #ifdef DIAGNOSTIC 363 if (slot) 364 panic("uao_set_swslot: didn't create elt"); 365 #endif 366 return (0); 367 } 368 369 oldslot = UAO_SWHASH_ELT_PAGESLOT(elt, pageidx); 370 UAO_SWHASH_ELT_PAGESLOT(elt, pageidx) = slot; 371 372 /* 373 * now adjust the elt's reference counter and free it if we've 374 * dropped it to zero. 375 */ 376 377 /* an allocation? */ 378 if (slot) { 379 if (oldslot == 0) 380 elt->count++; 381 } else { /* freeing slot ... */ 382 if (oldslot) /* to be safe */ 383 elt->count--; 384 385 if (elt->count == 0) { 386 LIST_REMOVE(elt, list); 387 pool_put(&uao_swhash_elt_pool, elt); 388 } 389 } 390 391 } else { 392 /* we are using an array */ 393 oldslot = aobj->u_swslots[pageidx]; 394 aobj->u_swslots[pageidx] = slot; 395 } 396 return (oldslot); 397 } 398 399 /* 400 * end of hash/array functions 401 */ 402 403 /* 404 * uao_free: free all resources held by an aobj, and then free the aobj 405 * 406 * => the aobj should be dead 407 */ 408 static void 409 uao_free(aobj) 410 struct uvm_aobj *aobj; 411 { 412 413 if (UAO_USES_SWHASH(aobj)) { 414 int i, hashbuckets = aobj->u_swhashmask + 1; 415 416 /* 417 * free the swslots from each hash bucket, 418 * then the hash bucket, and finally the hash table itself. 419 */ 420 for (i = 0; i < hashbuckets; i++) { 421 struct uao_swhash_elt *elt, *next; 422 423 for (elt = aobj->u_swhash[i].lh_first; elt != NULL; 424 elt = next) { 425 int j; 426 427 for (j = 0; j < UAO_SWHASH_CLUSTER_SIZE; j++) 428 { 429 int slot = elt->slots[j]; 430 431 if (slot) 432 uvm_swap_free(slot, 1); 433 } 434 435 next = elt->list.le_next; 436 pool_put(&uao_swhash_elt_pool, elt); 437 } 438 } 439 FREE(aobj->u_swhash, M_UVMAOBJ); 440 } else { 441 int i; 442 443 /* 444 * free the array 445 */ 446 447 for (i = 0; i < aobj->u_pages; i++) 448 { 449 int slot = aobj->u_swslots[i]; 450 451 if (slot) 452 uvm_swap_free(slot, 1); 453 } 454 FREE(aobj->u_swslots, M_UVMAOBJ); 455 } 456 457 /* 458 * finally free the aobj itself 459 */ 460 pool_put(&uvm_aobj_pool, aobj); 461 } 462 463 /* 464 * pager functions 465 */ 466 467 /* 468 * uao_create: create an aobj of the given size and return its uvm_object. 469 * 470 * => for normal use, flags are always zero 471 * => for the kernel object, the flags are: 472 * UAO_FLAG_KERNOBJ - allocate the kernel object (can only happen once) 473 * UAO_FLAG_KERNSWAP - enable swapping of kernel object (" ") 474 */ 475 struct uvm_object * 476 uao_create(size, flags) 477 vsize_t size; 478 int flags; 479 { 480 static struct uvm_aobj kernel_object_store; /* home of kernel_object */ 481 static int kobj_alloced = 0; /* not allocated yet */ 482 int pages = round_page(size) >> PAGE_SHIFT; 483 struct uvm_aobj *aobj; 484 485 /* 486 * malloc a new aobj unless we are asked for the kernel object 487 */ 488 if (flags & UAO_FLAG_KERNOBJ) { /* want kernel object? */ 489 if (kobj_alloced) 490 panic("uao_create: kernel object already allocated"); 491 492 /* 493 * XXXTHORPEJ: Need to call this now, so the pool gets 494 * initialized! 495 */ 496 uao_init(); 497 498 aobj = &kernel_object_store; 499 aobj->u_pages = pages; 500 aobj->u_flags = UAO_FLAG_NOSWAP; /* no swap to start */ 501 /* we are special, we never die */ 502 aobj->u_obj.uo_refs = UVM_OBJ_KERN; 503 kobj_alloced = UAO_FLAG_KERNOBJ; 504 } else if (flags & UAO_FLAG_KERNSWAP) { 505 aobj = &kernel_object_store; 506 if (kobj_alloced != UAO_FLAG_KERNOBJ) 507 panic("uao_create: asked to enable swap on kernel object"); 508 kobj_alloced = UAO_FLAG_KERNSWAP; 509 } else { /* normal object */ 510 aobj = pool_get(&uvm_aobj_pool, PR_WAITOK); 511 aobj->u_pages = pages; 512 aobj->u_flags = 0; /* normal object */ 513 aobj->u_obj.uo_refs = 1; /* start with 1 reference */ 514 } 515 516 /* 517 * allocate hash/array if necessary 518 * 519 * note: in the KERNSWAP case no need to worry about locking since 520 * we are still booting we should be the only thread around. 521 */ 522 if (flags == 0 || (flags & UAO_FLAG_KERNSWAP) != 0) { 523 int mflags = (flags & UAO_FLAG_KERNSWAP) != 0 ? 524 M_NOWAIT : M_WAITOK; 525 526 /* allocate hash table or array depending on object size */ 527 if (UAO_USES_SWHASH(aobj)) { 528 aobj->u_swhash = hashinit(UAO_SWHASH_BUCKETS(aobj), 529 M_UVMAOBJ, mflags, &aobj->u_swhashmask); 530 if (aobj->u_swhash == NULL) 531 panic("uao_create: hashinit swhash failed"); 532 } else { 533 MALLOC(aobj->u_swslots, int *, pages * sizeof(int), 534 M_UVMAOBJ, mflags); 535 if (aobj->u_swslots == NULL) 536 panic("uao_create: malloc swslots failed"); 537 memset(aobj->u_swslots, 0, pages * sizeof(int)); 538 } 539 540 if (flags) { 541 aobj->u_flags &= ~UAO_FLAG_NOSWAP; /* clear noswap */ 542 return(&aobj->u_obj); 543 /* done! */ 544 } 545 } 546 547 /* 548 * init aobj fields 549 */ 550 simple_lock_init(&aobj->u_obj.vmobjlock); 551 aobj->u_obj.pgops = &aobj_pager; 552 TAILQ_INIT(&aobj->u_obj.memq); 553 aobj->u_obj.uo_npages = 0; 554 555 /* 556 * now that aobj is ready, add it to the global list 557 * XXXCHS: uao_init hasn't been called'd in the KERNOBJ case, 558 * do we really need the kernel object on this list anyway? 559 */ 560 simple_lock(&uao_list_lock); 561 LIST_INSERT_HEAD(&uao_list, aobj, u_list); 562 simple_unlock(&uao_list_lock); 563 564 /* 565 * done! 566 */ 567 return(&aobj->u_obj); 568 } 569 570 571 572 /* 573 * uao_init: set up aobj pager subsystem 574 * 575 * => called at boot time from uvm_pager_init() 576 */ 577 static void 578 uao_init() 579 { 580 static int uao_initialized; 581 582 if (uao_initialized) 583 return; 584 uao_initialized = TRUE; 585 586 LIST_INIT(&uao_list); 587 simple_lock_init(&uao_list_lock); 588 589 /* 590 * NOTE: Pages fror this pool must not come from a pageable 591 * kernel map! 592 */ 593 pool_init(&uao_swhash_elt_pool, sizeof(struct uao_swhash_elt), 594 0, 0, 0, "uaoeltpl", 0, NULL, NULL, M_UVMAOBJ); 595 596 pool_init(&uvm_aobj_pool, sizeof(struct uvm_aobj), 0, 0, 0, 597 "aobjpl", 0, 598 pool_page_alloc_nointr, pool_page_free_nointr, M_UVMAOBJ); 599 } 600 601 /* 602 * uao_reference: add a ref to an aobj 603 * 604 * => aobj must be unlocked (we will lock it) 605 */ 606 void 607 uao_reference(uobj) 608 struct uvm_object *uobj; 609 { 610 UVMHIST_FUNC("uao_reference"); UVMHIST_CALLED(maphist); 611 612 /* 613 * kernel_object already has plenty of references, leave it alone. 614 */ 615 616 if (uobj->uo_refs == UVM_OBJ_KERN) 617 return; 618 619 simple_lock(&uobj->vmobjlock); 620 uobj->uo_refs++; /* bump! */ 621 UVMHIST_LOG(maphist, "<- done (uobj=0x%x, ref = %d)", 622 uobj, uobj->uo_refs,0,0); 623 simple_unlock(&uobj->vmobjlock); 624 } 625 626 /* 627 * uao_detach: drop a reference to an aobj 628 * 629 * => aobj must be unlocked, we will lock it 630 */ 631 void 632 uao_detach(uobj) 633 struct uvm_object *uobj; 634 { 635 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 636 struct vm_page *pg; 637 boolean_t busybody; 638 UVMHIST_FUNC("uao_detach"); UVMHIST_CALLED(maphist); 639 640 /* 641 * detaching from kernel_object is a noop. 642 */ 643 if (uobj->uo_refs == UVM_OBJ_KERN) 644 return; 645 646 simple_lock(&uobj->vmobjlock); 647 648 UVMHIST_LOG(maphist," (uobj=0x%x) ref=%d", uobj,uobj->uo_refs,0,0); 649 uobj->uo_refs--; /* drop ref! */ 650 if (uobj->uo_refs) { /* still more refs? */ 651 simple_unlock(&uobj->vmobjlock); 652 UVMHIST_LOG(maphist, "<- done (rc>0)", 0,0,0,0); 653 return; 654 } 655 656 /* 657 * remove the aobj from the global list. 658 */ 659 simple_lock(&uao_list_lock); 660 LIST_REMOVE(aobj, u_list); 661 simple_unlock(&uao_list_lock); 662 663 /* 664 * free all the pages that aren't PG_BUSY, mark for release any that are. 665 */ 666 667 busybody = FALSE; 668 for (pg = uobj->memq.tqh_first ; pg != NULL ; pg = pg->listq.tqe_next) { 669 int swslot; 670 671 if (pg->flags & PG_BUSY) { 672 pg->flags |= PG_RELEASED; 673 busybody = TRUE; 674 continue; 675 } 676 677 678 /* zap the mappings, free the swap slot, free the page */ 679 pmap_page_protect(PMAP_PGARG(pg), VM_PROT_NONE); 680 681 swslot = uao_set_swslot(&aobj->u_obj, 682 pg->offset >> PAGE_SHIFT, 0); 683 if (swslot) { 684 uvm_swap_free(swslot, 1); 685 } 686 687 uvm_lock_pageq(); 688 uvm_pagefree(pg); 689 uvm_unlock_pageq(); 690 } 691 692 /* 693 * if we found any busy pages, we're done for now. 694 * mark the aobj for death, releasepg will finish up for us. 695 */ 696 if (busybody) { 697 aobj->u_flags |= UAO_FLAG_KILLME; 698 simple_unlock(&aobj->u_obj.vmobjlock); 699 return; 700 } 701 702 /* 703 * finally, free the rest. 704 */ 705 uao_free(aobj); 706 } 707 708 /* 709 * uao_flush: uh, yea, sure it's flushed. really! 710 */ 711 boolean_t 712 uao_flush(uobj, start, end, flags) 713 struct uvm_object *uobj; 714 vaddr_t start, end; 715 int flags; 716 { 717 718 /* 719 * anonymous memory doesn't "flush" 720 */ 721 /* 722 * XXX 723 * deal with PGO_DEACTIVATE (for madvise(MADV_SEQUENTIAL)) 724 * and PGO_FREE (for msync(MSINVALIDATE)) 725 */ 726 return TRUE; 727 } 728 729 /* 730 * uao_get: fetch me a page 731 * 732 * we have three cases: 733 * 1: page is resident -> just return the page. 734 * 2: page is zero-fill -> allocate a new page and zero it. 735 * 3: page is swapped out -> fetch the page from swap. 736 * 737 * cases 1 and 2 can be handled with PGO_LOCKED, case 3 cannot. 738 * so, if the "center" page hits case 3 (or any page, with PGO_ALLPAGES), 739 * then we will need to return VM_PAGER_UNLOCK. 740 * 741 * => prefer map unlocked (not required) 742 * => object must be locked! we will _unlock_ it before starting any I/O. 743 * => flags: PGO_ALLPAGES: get all of the pages 744 * PGO_LOCKED: fault data structures are locked 745 * => NOTE: offset is the offset of pps[0], _NOT_ pps[centeridx] 746 * => NOTE: caller must check for released pages!! 747 */ 748 static int 749 uao_get(uobj, offset, pps, npagesp, centeridx, access_type, advice, flags) 750 struct uvm_object *uobj; 751 vaddr_t offset; 752 struct vm_page **pps; 753 int *npagesp; 754 int centeridx, advice, flags; 755 vm_prot_t access_type; 756 { 757 struct uvm_aobj *aobj = (struct uvm_aobj *)uobj; 758 vaddr_t current_offset; 759 vm_page_t ptmp; 760 int lcv, gotpages, maxpages, swslot, rv; 761 boolean_t done; 762 UVMHIST_FUNC("uao_get"); UVMHIST_CALLED(pdhist); 763 764 UVMHIST_LOG(pdhist, "aobj=%p offset=%d, flags=%d", aobj, offset, flags,0); 765 766 /* 767 * get number of pages 768 */ 769 770 maxpages = *npagesp; 771 772 /* 773 * step 1: handled the case where fault data structures are locked. 774 */ 775 776 if (flags & PGO_LOCKED) { 777 778 /* 779 * step 1a: get pages that are already resident. only do 780 * this if the data structures are locked (i.e. the first 781 * time through). 782 */ 783 784 done = TRUE; /* be optimistic */ 785 gotpages = 0; /* # of pages we got so far */ 786 787 for (lcv = 0, current_offset = offset ; lcv < maxpages ; 788 lcv++, current_offset += PAGE_SIZE) { 789 /* do we care about this page? if not, skip it */ 790 if (pps[lcv] == PGO_DONTCARE) 791 continue; 792 793 ptmp = uvm_pagelookup(uobj, current_offset); 794 795 /* 796 * if page is new, attempt to allocate the page, then 797 * zero-fill it. 798 */ 799 if (ptmp == NULL && uao_find_swslot(aobj, 800 current_offset >> PAGE_SHIFT) == 0) { 801 ptmp = uvm_pagealloc(uobj, current_offset, 802 NULL); 803 if (ptmp) { 804 /* new page */ 805 ptmp->flags &= ~(PG_BUSY|PG_FAKE); 806 ptmp->pqflags |= PQ_AOBJ; 807 UVM_PAGE_OWN(ptmp, NULL); 808 uvm_pagezero(ptmp); 809 } 810 } 811 812 /* 813 * to be useful must get a non-busy, non-released page 814 */ 815 if (ptmp == NULL || 816 (ptmp->flags & (PG_BUSY|PG_RELEASED)) != 0) { 817 if (lcv == centeridx || 818 (flags & PGO_ALLPAGES) != 0) 819 /* need to do a wait or I/O! */ 820 done = FALSE; 821 continue; 822 } 823 824 /* 825 * useful page: busy/lock it and plug it in our 826 * result array 827 */ 828 /* caller must un-busy this page */ 829 ptmp->flags |= PG_BUSY; 830 UVM_PAGE_OWN(ptmp, "uao_get1"); 831 pps[lcv] = ptmp; 832 gotpages++; 833 834 } /* "for" lcv loop */ 835 836 /* 837 * step 1b: now we've either done everything needed or we 838 * to unlock and do some waiting or I/O. 839 */ 840 841 UVMHIST_LOG(pdhist, "<- done (done=%d)", done, 0,0,0); 842 843 *npagesp = gotpages; 844 if (done) 845 /* bingo! */ 846 return(VM_PAGER_OK); 847 else 848 /* EEK! Need to unlock and I/O */ 849 return(VM_PAGER_UNLOCK); 850 } 851 852 /* 853 * step 2: get non-resident or busy pages. 854 * object is locked. data structures are unlocked. 855 */ 856 857 for (lcv = 0, current_offset = offset ; lcv < maxpages ; 858 lcv++, current_offset += PAGE_SIZE) { 859 /* 860 * - skip over pages we've already gotten or don't want 861 * - skip over pages we don't _have_ to get 862 */ 863 if (pps[lcv] != NULL || 864 (lcv != centeridx && (flags & PGO_ALLPAGES) == 0)) 865 continue; 866 867 /* 868 * we have yet to locate the current page (pps[lcv]). we 869 * first look for a page that is already at the current offset. 870 * if we find a page, we check to see if it is busy or 871 * released. if that is the case, then we sleep on the page 872 * until it is no longer busy or released and repeat the lookup. 873 * if the page we found is neither busy nor released, then we 874 * busy it (so we own it) and plug it into pps[lcv]. this 875 * 'break's the following while loop and indicates we are 876 * ready to move on to the next page in the "lcv" loop above. 877 * 878 * if we exit the while loop with pps[lcv] still set to NULL, 879 * then it means that we allocated a new busy/fake/clean page 880 * ptmp in the object and we need to do I/O to fill in the data. 881 */ 882 883 /* top of "pps" while loop */ 884 while (pps[lcv] == NULL) { 885 /* look for a resident page */ 886 ptmp = uvm_pagelookup(uobj, current_offset); 887 888 /* not resident? allocate one now (if we can) */ 889 if (ptmp == NULL) { 890 891 ptmp = uvm_pagealloc(uobj, current_offset, 892 NULL); /* alloc */ 893 894 /* out of RAM? */ 895 if (ptmp == NULL) { 896 simple_unlock(&uobj->vmobjlock); 897 UVMHIST_LOG(pdhist, 898 "sleeping, ptmp == NULL\n",0,0,0,0); 899 uvm_wait("uao_getpage"); 900 simple_lock(&uobj->vmobjlock); 901 /* goto top of pps while loop */ 902 continue; 903 } 904 905 /* 906 * safe with PQ's unlocked: because we just 907 * alloc'd the page 908 */ 909 ptmp->pqflags |= PQ_AOBJ; 910 911 /* 912 * got new page ready for I/O. break pps while 913 * loop. pps[lcv] is still NULL. 914 */ 915 break; 916 } 917 918 /* page is there, see if we need to wait on it */ 919 if ((ptmp->flags & (PG_BUSY|PG_RELEASED)) != 0) { 920 ptmp->flags |= PG_WANTED; 921 UVMHIST_LOG(pdhist, 922 "sleeping, ptmp->flags 0x%x\n", 923 ptmp->flags,0,0,0); 924 UVM_UNLOCK_AND_WAIT(ptmp, &uobj->vmobjlock, 0, 925 "uao_get", 0); 926 simple_lock(&uobj->vmobjlock); 927 continue; /* goto top of pps while loop */ 928 } 929 930 /* 931 * if we get here then the page has become resident and 932 * unbusy between steps 1 and 2. we busy it now (so we 933 * own it) and set pps[lcv] (so that we exit the while 934 * loop). 935 */ 936 /* we own it, caller must un-busy */ 937 ptmp->flags |= PG_BUSY; 938 UVM_PAGE_OWN(ptmp, "uao_get2"); 939 pps[lcv] = ptmp; 940 } 941 942 /* 943 * if we own the valid page at the correct offset, pps[lcv] will 944 * point to it. nothing more to do except go to the next page. 945 */ 946 if (pps[lcv]) 947 continue; /* next lcv */ 948 949 /* 950 * we have a "fake/busy/clean" page that we just allocated. 951 * do the needed "i/o", either reading from swap or zeroing. 952 */ 953 swslot = uao_find_swslot(aobj, current_offset >> PAGE_SHIFT); 954 955 /* 956 * just zero the page if there's nothing in swap. 957 */ 958 if (swslot == 0) 959 { 960 /* 961 * page hasn't existed before, just zero it. 962 */ 963 uvm_pagezero(ptmp); 964 } 965 else 966 { 967 UVMHIST_LOG(pdhist, "pagein from swslot %d", 968 swslot, 0,0,0); 969 970 /* 971 * page in the swapped-out page. 972 * unlock object for i/o, relock when done. 973 */ 974 simple_unlock(&uobj->vmobjlock); 975 rv = uvm_swap_get(ptmp, swslot, PGO_SYNCIO); 976 simple_lock(&uobj->vmobjlock); 977 978 /* 979 * I/O done. check for errors. 980 */ 981 if (rv != VM_PAGER_OK) 982 { 983 UVMHIST_LOG(pdhist, "<- done (error=%d)", 984 rv,0,0,0); 985 if (ptmp->flags & PG_WANTED) 986 /* object lock still held */ 987 thread_wakeup(ptmp); 988 ptmp->flags &= ~(PG_WANTED|PG_BUSY); 989 UVM_PAGE_OWN(ptmp, NULL); 990 uvm_lock_pageq(); 991 uvm_pagefree(ptmp); 992 uvm_unlock_pageq(); 993 simple_unlock(&uobj->vmobjlock); 994 return (rv); 995 } 996 } 997 998 /* 999 * we got the page! clear the fake flag (indicates valid 1000 * data now in page) and plug into our result array. note 1001 * that page is still busy. 1002 * 1003 * it is the callers job to: 1004 * => check if the page is released 1005 * => unbusy the page 1006 * => activate the page 1007 */ 1008 1009 ptmp->flags &= ~PG_FAKE; /* data is valid ... */ 1010 pmap_clear_modify(PMAP_PGARG(ptmp)); /* ... and clean */ 1011 pps[lcv] = ptmp; 1012 1013 } /* lcv loop */ 1014 1015 /* 1016 * finally, unlock object and return. 1017 */ 1018 1019 simple_unlock(&uobj->vmobjlock); 1020 UVMHIST_LOG(pdhist, "<- done (OK)",0,0,0,0); 1021 return(VM_PAGER_OK); 1022 } 1023 1024 /* 1025 * uao_releasepg: handle released page in an aobj 1026 * 1027 * => "pg" is a PG_BUSY [caller owns it], PG_RELEASED page that we need 1028 * to dispose of. 1029 * => caller must handle PG_WANTED case 1030 * => called with page's object locked, pageq's unlocked 1031 * => returns TRUE if page's object is still alive, FALSE if we 1032 * killed the page's object. if we return TRUE, then we 1033 * return with the object locked. 1034 * => if (nextpgp != NULL) => we return pageq.tqe_next here, and return 1035 * with the page queues locked [for pagedaemon] 1036 * => if (nextpgp == NULL) => we return with page queues unlocked [normal case] 1037 * => we kill the aobj if it is not referenced and we are suppose to 1038 * kill it ("KILLME"). 1039 */ 1040 static boolean_t uao_releasepg(pg, nextpgp) 1041 struct vm_page *pg; 1042 struct vm_page **nextpgp; /* OUT */ 1043 { 1044 struct uvm_aobj *aobj = (struct uvm_aobj *) pg->uobject; 1045 int slot; 1046 1047 #ifdef DIAGNOSTIC 1048 if ((pg->flags & PG_RELEASED) == 0) 1049 panic("uao_releasepg: page not released!"); 1050 #endif 1051 1052 /* 1053 * dispose of the page [caller handles PG_WANTED] and swap slot. 1054 */ 1055 pmap_page_protect(PMAP_PGARG(pg), VM_PROT_NONE); 1056 slot = uao_set_swslot(&aobj->u_obj, pg->offset >> PAGE_SHIFT, 0); 1057 if (slot) 1058 uvm_swap_free(slot, 1); 1059 uvm_lock_pageq(); 1060 if (nextpgp) 1061 *nextpgp = pg->pageq.tqe_next; /* next page for daemon */ 1062 uvm_pagefree(pg); 1063 if (!nextpgp) 1064 uvm_unlock_pageq(); /* keep locked for daemon */ 1065 1066 /* 1067 * if we're not killing the object, we're done. 1068 */ 1069 if ((aobj->u_flags & UAO_FLAG_KILLME) == 0) 1070 return TRUE; 1071 1072 #ifdef DIAGNOSTIC 1073 if (aobj->u_obj.uo_refs) 1074 panic("uvm_km_releasepg: kill flag set on referenced object!"); 1075 #endif 1076 1077 /* 1078 * if there are still pages in the object, we're done for now. 1079 */ 1080 if (aobj->u_obj.uo_npages != 0) 1081 return TRUE; 1082 1083 #ifdef DIAGNOSTIC 1084 if (aobj->u_obj.memq.tqh_first) 1085 panic("uvn_releasepg: pages in object with npages == 0"); 1086 #endif 1087 1088 /* 1089 * finally, free the rest. 1090 */ 1091 uao_free(aobj); 1092 1093 return FALSE; 1094 } 1095