1 /* $OpenBSD: uvm_km.c,v 1.128 2015/09/26 17:55:00 kettenis Exp $ */ 2 /* $NetBSD: uvm_km.c,v 1.42 2001/01/14 02:10:01 thorpej Exp $ */ 3 4 /* 5 * Copyright (c) 1997 Charles D. Cranor and Washington University. 6 * Copyright (c) 1991, 1993, The Regents of the University of California. 7 * 8 * All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * The Mach Operating System project at Carnegie-Mellon University. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)vm_kern.c 8.3 (Berkeley) 1/12/94 38 * from: Id: uvm_km.c,v 1.1.2.14 1998/02/06 05:19:27 chs Exp 39 * 40 * 41 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 42 * All rights reserved. 43 * 44 * Permission to use, copy, modify and distribute this software and 45 * its documentation is hereby granted, provided that both the copyright 46 * notice and this permission notice appear in all copies of the 47 * software, derivative works or modified versions, and any portions 48 * thereof, and that both notices appear in supporting documentation. 49 * 50 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 51 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 52 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 53 * 54 * Carnegie Mellon requests users of this software to return to 55 * 56 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 57 * School of Computer Science 58 * Carnegie Mellon University 59 * Pittsburgh PA 15213-3890 60 * 61 * any improvements or extensions that they make and grant Carnegie the 62 * rights to redistribute these changes. 63 */ 64 65 /* 66 * uvm_km.c: handle kernel memory allocation and management 67 */ 68 69 /* 70 * overview of kernel memory management: 71 * 72 * the kernel virtual address space is mapped by "kernel_map." kernel_map 73 * starts at a machine-dependent address and is VM_KERNEL_SPACE_SIZE bytes 74 * large. 75 * 76 * the kernel_map has several "submaps." submaps can only appear in 77 * the kernel_map (user processes can't use them). submaps "take over" 78 * the management of a sub-range of the kernel's address space. submaps 79 * are typically allocated at boot time and are never released. kernel 80 * virtual address space that is mapped by a submap is locked by the 81 * submap's lock -- not the kernel_map's lock. 82 * 83 * thus, the useful feature of submaps is that they allow us to break 84 * up the locking and protection of the kernel address space into smaller 85 * chunks. 86 * 87 * The VM system has several standard kernel submaps: 88 * kmem_map: Contains only wired kernel memory for malloc(9). 89 * Note: All access to this map must be protected by splvm as 90 * calls to malloc(9) are allowed in interrupt handlers. 91 * exec_map: Memory to hold arguments to system calls are allocated from 92 * this map. 93 * XXX: This is primeraly used to artificially limit the number 94 * of concurrent processes doing an exec. 95 * phys_map: Buffers for vmapbuf (physio) are allocated from this map. 96 * 97 * the kernel allocates its private memory out of special uvm_objects whose 98 * reference count is set to UVM_OBJ_KERN (thus indicating that the objects 99 * are "special" and never die). all kernel objects should be thought of 100 * as large, fixed-sized, sparsely populated uvm_objects. each kernel 101 * object is equal to the size of kernel virtual address space (i.e. 102 * VM_KERNEL_SPACE_SIZE). 103 * 104 * most kernel private memory lives in kernel_object. the only exception 105 * to this is for memory that belongs to submaps that must be protected 106 * by splvm(). each of these submaps manages their own pages. 107 * 108 * note that just because a kernel object spans the entire kernel virtual 109 * address space doesn't mean that it has to be mapped into the entire space. 110 * large chunks of a kernel object's space go unused either because 111 * that area of kernel VM is unmapped, or there is some other type of 112 * object mapped into that range (e.g. a vnode). for submap's kernel 113 * objects, the only part of the object that can ever be populated is the 114 * offsets that are managed by the submap. 115 * 116 * note that the "offset" in a kernel object is always the kernel virtual 117 * address minus the vm_map_min(kernel_map). 118 * example: 119 * suppose kernel_map starts at 0xf8000000 and the kernel does a 120 * uvm_km_alloc(kernel_map, PAGE_SIZE) [allocate 1 wired down page in the 121 * kernel map]. if uvm_km_alloc returns virtual address 0xf8235000, 122 * then that means that the page at offset 0x235000 in kernel_object is 123 * mapped at 0xf8235000. 124 * 125 * kernel objects have one other special property: when the kernel virtual 126 * memory mapping them is unmapped, the backing memory in the object is 127 * freed right away. this is done with the uvm_km_pgremove() function. 128 * this has to be done because there is no backing store for kernel pages 129 * and no need to save them after they are no longer referenced. 130 */ 131 132 #include <sys/param.h> 133 #include <sys/systm.h> 134 #include <sys/kthread.h> 135 #include <uvm/uvm.h> 136 137 /* 138 * global data structures 139 */ 140 141 struct vm_map *kernel_map = NULL; 142 143 /* Unconstraint range. */ 144 struct uvm_constraint_range no_constraint = { 0x0, (paddr_t)-1 }; 145 146 /* 147 * local data structues 148 */ 149 static struct vm_map kernel_map_store; 150 151 /* 152 * uvm_km_init: init kernel maps and objects to reflect reality (i.e. 153 * KVM already allocated for text, data, bss, and static data structures). 154 * 155 * => KVM is defined by [base.. base + VM_KERNEL_SPACE_SIZE]. 156 * we assume that [base -> start] has already been allocated and that 157 * "end" is the end of the kernel image span. 158 */ 159 void 160 uvm_km_init(vaddr_t base, vaddr_t start, vaddr_t end) 161 { 162 /* kernel_object: for pageable anonymous kernel memory */ 163 uao_init(); 164 uvm.kernel_object = uao_create(VM_KERNEL_SPACE_SIZE, UAO_FLAG_KERNOBJ); 165 166 /* 167 * init the map and reserve already allocated kernel space 168 * before installing. 169 */ 170 171 uvm_map_setup(&kernel_map_store, base, end, 172 #ifdef KVA_GUARDPAGES 173 VM_MAP_PAGEABLE | VM_MAP_GUARDPAGES 174 #else 175 VM_MAP_PAGEABLE 176 #endif 177 ); 178 kernel_map_store.pmap = pmap_kernel(); 179 if (base != start && uvm_map(&kernel_map_store, &base, start - base, 180 NULL, UVM_UNKNOWN_OFFSET, 0, 181 UVM_MAPFLAG(PROT_READ | PROT_WRITE, PROT_READ | PROT_WRITE, 182 MAP_INHERIT_NONE, MADV_RANDOM, UVM_FLAG_FIXED)) != 0) 183 panic("uvm_km_init: could not reserve space for kernel"); 184 185 kernel_map = &kernel_map_store; 186 } 187 188 /* 189 * uvm_km_suballoc: allocate a submap in the kernel map. once a submap 190 * is allocated all references to that area of VM must go through it. this 191 * allows the locking of VAs in kernel_map to be broken up into regions. 192 * 193 * => if `fixed' is true, *min specifies where the region described 194 * by the submap must start 195 * => if submap is non NULL we use that as the submap, otherwise we 196 * alloc a new map 197 */ 198 struct vm_map * 199 uvm_km_suballoc(struct vm_map *map, vaddr_t *min, vaddr_t *max, vsize_t size, 200 int flags, boolean_t fixed, struct vm_map *submap) 201 { 202 int mapflags = UVM_FLAG_NOMERGE | (fixed ? UVM_FLAG_FIXED : 0); 203 204 size = round_page(size); /* round up to pagesize */ 205 206 /* first allocate a blank spot in the parent map */ 207 if (uvm_map(map, min, size, NULL, UVM_UNKNOWN_OFFSET, 0, 208 UVM_MAPFLAG(PROT_READ | PROT_WRITE, PROT_READ | PROT_WRITE, 209 MAP_INHERIT_NONE, MADV_RANDOM, mapflags)) != 0) { 210 panic("uvm_km_suballoc: unable to allocate space in parent map"); 211 } 212 213 /* set VM bounds (min is filled in by uvm_map) */ 214 *max = *min + size; 215 216 /* add references to pmap and create or init the submap */ 217 pmap_reference(vm_map_pmap(map)); 218 if (submap == NULL) { 219 submap = uvm_map_create(vm_map_pmap(map), *min, *max, flags); 220 if (submap == NULL) 221 panic("uvm_km_suballoc: unable to create submap"); 222 } else { 223 uvm_map_setup(submap, *min, *max, flags); 224 submap->pmap = vm_map_pmap(map); 225 } 226 227 /* now let uvm_map_submap plug in it... */ 228 if (uvm_map_submap(map, *min, *max, submap) != 0) 229 panic("uvm_km_suballoc: submap allocation failed"); 230 231 return(submap); 232 } 233 234 /* 235 * uvm_km_pgremove: remove pages from a kernel uvm_object. 236 * 237 * => when you unmap a part of anonymous kernel memory you want to toss 238 * the pages right away. (this gets called from uvm_unmap_...). 239 */ 240 void 241 uvm_km_pgremove(struct uvm_object *uobj, vaddr_t start, vaddr_t end) 242 { 243 struct vm_page *pp; 244 voff_t curoff; 245 int slot; 246 247 KASSERT(uobj->pgops == &aobj_pager); 248 249 for (curoff = start ; curoff < end ; curoff += PAGE_SIZE) { 250 pp = uvm_pagelookup(uobj, curoff); 251 if (pp && pp->pg_flags & PG_BUSY) { 252 atomic_setbits_int(&pp->pg_flags, PG_WANTED); 253 UVM_WAIT(pp, 0, "km_pgrm", 0); 254 curoff -= PAGE_SIZE; /* loop back to us */ 255 continue; 256 } 257 258 /* free the swap slot, then the page */ 259 slot = uao_dropswap(uobj, curoff >> PAGE_SHIFT); 260 261 if (pp != NULL) { 262 uvm_lock_pageq(); 263 uvm_pagefree(pp); 264 uvm_unlock_pageq(); 265 } else if (slot != 0) { 266 uvmexp.swpgonly--; 267 } 268 } 269 } 270 271 272 /* 273 * uvm_km_pgremove_intrsafe: like uvm_km_pgremove(), but for "intrsafe" 274 * objects 275 * 276 * => when you unmap a part of anonymous kernel memory you want to toss 277 * the pages right away. (this gets called from uvm_unmap_...). 278 * => none of the pages will ever be busy, and none of them will ever 279 * be on the active or inactive queues (because these objects are 280 * never allowed to "page"). 281 */ 282 void 283 uvm_km_pgremove_intrsafe(vaddr_t start, vaddr_t end) 284 { 285 struct vm_page *pg; 286 vaddr_t va; 287 paddr_t pa; 288 289 for (va = start; va < end; va += PAGE_SIZE) { 290 if (!pmap_extract(pmap_kernel(), va, &pa)) 291 continue; 292 pg = PHYS_TO_VM_PAGE(pa); 293 if (pg == NULL) 294 panic("uvm_km_pgremove_intrsafe: no page"); 295 uvm_pagefree(pg); 296 } 297 } 298 299 /* 300 * uvm_km_kmemalloc: lower level kernel memory allocator for malloc() 301 * 302 * => we map wired memory into the specified map using the obj passed in 303 * => NOTE: we can return NULL even if we can wait if there is not enough 304 * free VM space in the map... caller should be prepared to handle 305 * this case. 306 * => we return KVA of memory allocated 307 * => flags: NOWAIT, VALLOC - just allocate VA, TRYLOCK - fail if we can't 308 * lock the map 309 * => low, high, alignment, boundary, nsegs are the corresponding parameters 310 * to uvm_pglistalloc 311 * => flags: ZERO - correspond to uvm_pglistalloc flags 312 */ 313 vaddr_t 314 uvm_km_kmemalloc_pla(struct vm_map *map, struct uvm_object *obj, vsize_t size, 315 vsize_t valign, int flags, paddr_t low, paddr_t high, paddr_t alignment, 316 paddr_t boundary, int nsegs) 317 { 318 vaddr_t kva, loopva; 319 voff_t offset; 320 struct vm_page *pg; 321 struct pglist pgl; 322 int pla_flags; 323 324 KASSERT(vm_map_pmap(map) == pmap_kernel()); 325 /* UVM_KMF_VALLOC => !UVM_KMF_ZERO */ 326 KASSERT(!(flags & UVM_KMF_VALLOC) || 327 !(flags & UVM_KMF_ZERO)); 328 329 /* setup for call */ 330 size = round_page(size); 331 kva = vm_map_min(map); /* hint */ 332 if (nsegs == 0) 333 nsegs = atop(size); 334 335 /* allocate some virtual space */ 336 if (__predict_false(uvm_map(map, &kva, size, obj, UVM_UNKNOWN_OFFSET, 337 valign, UVM_MAPFLAG(PROT_READ | PROT_WRITE, PROT_READ | PROT_WRITE, 338 MAP_INHERIT_NONE, MADV_RANDOM, (flags & UVM_KMF_TRYLOCK))) != 0)) { 339 return(0); 340 } 341 342 /* if all we wanted was VA, return now */ 343 if (flags & UVM_KMF_VALLOC) { 344 return(kva); 345 } 346 347 /* recover object offset from virtual address */ 348 if (obj != NULL) 349 offset = kva - vm_map_min(kernel_map); 350 else 351 offset = 0; 352 353 /* 354 * now allocate and map in the memory... note that we are the only ones 355 * whom should ever get a handle on this area of VM. 356 */ 357 TAILQ_INIT(&pgl); 358 pla_flags = 0; 359 KASSERT(uvmexp.swpgonly <= uvmexp.swpages); 360 if ((flags & UVM_KMF_NOWAIT) || 361 ((flags & UVM_KMF_CANFAIL) && 362 uvmexp.swpages - uvmexp.swpgonly <= atop(size))) 363 pla_flags |= UVM_PLA_NOWAIT; 364 else 365 pla_flags |= UVM_PLA_WAITOK; 366 if (flags & UVM_KMF_ZERO) 367 pla_flags |= UVM_PLA_ZERO; 368 if (uvm_pglistalloc(size, low, high, alignment, boundary, &pgl, nsegs, 369 pla_flags) != 0) { 370 /* Failed. */ 371 uvm_unmap(map, kva, kva + size); 372 return (0); 373 } 374 375 loopva = kva; 376 while (loopva != kva + size) { 377 pg = TAILQ_FIRST(&pgl); 378 TAILQ_REMOVE(&pgl, pg, pageq); 379 uvm_pagealloc_pg(pg, obj, offset, NULL); 380 atomic_clearbits_int(&pg->pg_flags, PG_BUSY); 381 UVM_PAGE_OWN(pg, NULL); 382 383 /* 384 * map it in: note that we call pmap_enter with the map and 385 * object unlocked in case we are kmem_map. 386 */ 387 if (obj == NULL) { 388 pmap_kenter_pa(loopva, VM_PAGE_TO_PHYS(pg), 389 PROT_READ | PROT_WRITE); 390 } else { 391 pmap_enter(map->pmap, loopva, VM_PAGE_TO_PHYS(pg), 392 PROT_READ | PROT_WRITE, 393 PROT_READ | PROT_WRITE | PMAP_WIRED); 394 } 395 loopva += PAGE_SIZE; 396 offset += PAGE_SIZE; 397 } 398 KASSERT(TAILQ_EMPTY(&pgl)); 399 pmap_update(pmap_kernel()); 400 401 return(kva); 402 } 403 404 /* 405 * uvm_km_free: free an area of kernel memory 406 */ 407 void 408 uvm_km_free(struct vm_map *map, vaddr_t addr, vsize_t size) 409 { 410 uvm_unmap(map, trunc_page(addr), round_page(addr+size)); 411 } 412 413 /* 414 * uvm_km_free_wakeup: free an area of kernel memory and wake up 415 * anyone waiting for vm space. 416 * 417 * => XXX: "wanted" bit + unlock&wait on other end? 418 */ 419 void 420 uvm_km_free_wakeup(struct vm_map *map, vaddr_t addr, vsize_t size) 421 { 422 struct uvm_map_deadq dead_entries; 423 424 vm_map_lock(map); 425 TAILQ_INIT(&dead_entries); 426 uvm_unmap_remove(map, trunc_page(addr), round_page(addr+size), 427 &dead_entries, FALSE, TRUE); 428 wakeup(map); 429 vm_map_unlock(map); 430 431 uvm_unmap_detach(&dead_entries, 0); 432 } 433 434 /* 435 * uvm_km_alloc1: allocate wired down memory in the kernel map. 436 * 437 * => we can sleep if needed 438 */ 439 vaddr_t 440 uvm_km_alloc1(struct vm_map *map, vsize_t size, vsize_t align, boolean_t zeroit) 441 { 442 vaddr_t kva, loopva; 443 voff_t offset; 444 struct vm_page *pg; 445 446 KASSERT(vm_map_pmap(map) == pmap_kernel()); 447 448 size = round_page(size); 449 kva = vm_map_min(map); /* hint */ 450 451 /* allocate some virtual space */ 452 if (__predict_false(uvm_map(map, &kva, size, uvm.kernel_object, 453 UVM_UNKNOWN_OFFSET, align, 454 UVM_MAPFLAG(PROT_READ | PROT_WRITE, 455 PROT_READ | PROT_WRITE | PROT_EXEC, 456 MAP_INHERIT_NONE, MADV_RANDOM, 0)) != 0)) { 457 return(0); 458 } 459 460 /* recover object offset from virtual address */ 461 offset = kva - vm_map_min(kernel_map); 462 463 /* now allocate the memory. we must be careful about released pages. */ 464 loopva = kva; 465 while (size) { 466 /* allocate ram */ 467 pg = uvm_pagealloc(uvm.kernel_object, offset, NULL, 0); 468 if (pg) { 469 atomic_clearbits_int(&pg->pg_flags, PG_BUSY); 470 UVM_PAGE_OWN(pg, NULL); 471 } 472 if (__predict_false(pg == NULL)) { 473 if (curproc == uvm.pagedaemon_proc) { 474 /* 475 * It is unfeasible for the page daemon to 476 * sleep for memory, so free what we have 477 * allocated and fail. 478 */ 479 uvm_unmap(map, kva, loopva - kva); 480 return (0); 481 } else { 482 uvm_wait("km_alloc1w"); /* wait for memory */ 483 continue; 484 } 485 } 486 487 /* 488 * map it in; note we're never called with an intrsafe 489 * object, so we always use regular old pmap_enter(). 490 */ 491 pmap_enter(map->pmap, loopva, VM_PAGE_TO_PHYS(pg), 492 PROT_READ | PROT_WRITE, 493 PROT_READ | PROT_WRITE | PMAP_WIRED); 494 495 loopva += PAGE_SIZE; 496 offset += PAGE_SIZE; 497 size -= PAGE_SIZE; 498 } 499 pmap_update(map->pmap); 500 501 /* 502 * zero on request (note that "size" is now zero due to the above loop 503 * so we need to subtract kva from loopva to reconstruct the size). 504 */ 505 if (zeroit) 506 memset((caddr_t)kva, 0, loopva - kva); 507 508 return(kva); 509 } 510 511 /* 512 * uvm_km_valloc: allocate zero-fill memory in the kernel's address space 513 * 514 * => memory is not allocated until fault time 515 */ 516 517 vaddr_t 518 uvm_km_valloc(struct vm_map *map, vsize_t size) 519 { 520 return(uvm_km_valloc_align(map, size, 0, 0)); 521 } 522 523 vaddr_t 524 uvm_km_valloc_try(struct vm_map *map, vsize_t size) 525 { 526 return(uvm_km_valloc_align(map, size, 0, UVM_FLAG_TRYLOCK)); 527 } 528 529 vaddr_t 530 uvm_km_valloc_align(struct vm_map *map, vsize_t size, vsize_t align, int flags) 531 { 532 vaddr_t kva; 533 534 KASSERT(vm_map_pmap(map) == pmap_kernel()); 535 536 size = round_page(size); 537 kva = vm_map_min(map); /* hint */ 538 539 /* allocate some virtual space, demand filled by kernel_object. */ 540 541 if (__predict_false(uvm_map(map, &kva, size, uvm.kernel_object, 542 UVM_UNKNOWN_OFFSET, align, 543 UVM_MAPFLAG(PROT_READ | PROT_WRITE, PROT_READ | PROT_WRITE, 544 MAP_INHERIT_NONE, MADV_RANDOM, flags)) != 0)) { 545 return(0); 546 } 547 548 return(kva); 549 } 550 551 /* 552 * uvm_km_valloc_wait: allocate zero-fill memory in the kernel's address space 553 * 554 * => memory is not allocated until fault time 555 * => if no room in map, wait for space to free, unless requested size 556 * is larger than map (in which case we return 0) 557 */ 558 vaddr_t 559 uvm_km_valloc_prefer_wait(struct vm_map *map, vsize_t size, voff_t prefer) 560 { 561 vaddr_t kva; 562 563 KASSERT(vm_map_pmap(map) == pmap_kernel()); 564 565 size = round_page(size); 566 if (size > vm_map_max(map) - vm_map_min(map)) 567 return(0); 568 569 while (1) { 570 kva = vm_map_min(map); /* hint */ 571 572 /* 573 * allocate some virtual space. will be demand filled 574 * by kernel_object. 575 */ 576 if (__predict_true(uvm_map(map, &kva, size, uvm.kernel_object, 577 prefer, 0, 578 UVM_MAPFLAG(PROT_READ | PROT_WRITE, PROT_READ | PROT_WRITE, 579 MAP_INHERIT_NONE, MADV_RANDOM, 0)) == 0)) { 580 return(kva); 581 } 582 583 /* failed. sleep for a while (on map) */ 584 tsleep(map, PVM, "vallocwait", 0); 585 } 586 /*NOTREACHED*/ 587 } 588 589 vaddr_t 590 uvm_km_valloc_wait(struct vm_map *map, vsize_t size) 591 { 592 return uvm_km_valloc_prefer_wait(map, size, UVM_UNKNOWN_OFFSET); 593 } 594 595 #if defined(__HAVE_PMAP_DIRECT) 596 /* 597 * uvm_km_page allocator, __HAVE_PMAP_DIRECT arch 598 * On architectures with machine memory direct mapped into a portion 599 * of KVM, we have very little work to do. Just get a physical page, 600 * and find and return its VA. 601 */ 602 void 603 uvm_km_page_init(void) 604 { 605 /* nothing */ 606 } 607 608 #else 609 /* 610 * uvm_km_page allocator, non __HAVE_PMAP_DIRECT archs 611 * This is a special allocator that uses a reserve of free pages 612 * to fulfill requests. It is fast and interrupt safe, but can only 613 * return page sized regions. Its primary use is as a backend for pool. 614 * 615 * The memory returned is allocated from the larger kernel_map, sparing 616 * pressure on the small interrupt-safe kmem_map. It is wired, but 617 * not zero filled. 618 */ 619 620 struct uvm_km_pages uvm_km_pages; 621 622 void uvm_km_createthread(void *); 623 void uvm_km_thread(void *); 624 struct uvm_km_free_page *uvm_km_doputpage(struct uvm_km_free_page *); 625 626 /* 627 * Allocate the initial reserve, and create the thread which will 628 * keep the reserve full. For bootstrapping, we allocate more than 629 * the lowat amount, because it may be a while before the thread is 630 * running. 631 */ 632 void 633 uvm_km_page_init(void) 634 { 635 int lowat_min; 636 int i; 637 int len, bulk; 638 vaddr_t addr; 639 640 mtx_init(&uvm_km_pages.mtx, IPL_VM); 641 if (!uvm_km_pages.lowat) { 642 /* based on physmem, calculate a good value here */ 643 uvm_km_pages.lowat = physmem / 256; 644 lowat_min = physmem < atop(16 * 1024 * 1024) ? 32 : 128; 645 if (uvm_km_pages.lowat < lowat_min) 646 uvm_km_pages.lowat = lowat_min; 647 } 648 if (uvm_km_pages.lowat > UVM_KM_PAGES_LOWAT_MAX) 649 uvm_km_pages.lowat = UVM_KM_PAGES_LOWAT_MAX; 650 uvm_km_pages.hiwat = 4 * uvm_km_pages.lowat; 651 if (uvm_km_pages.hiwat > UVM_KM_PAGES_HIWAT_MAX) 652 uvm_km_pages.hiwat = UVM_KM_PAGES_HIWAT_MAX; 653 654 /* Allocate all pages in as few allocations as possible. */ 655 len = 0; 656 bulk = uvm_km_pages.hiwat; 657 while (len < uvm_km_pages.hiwat && bulk > 0) { 658 bulk = MIN(bulk, uvm_km_pages.hiwat - len); 659 addr = vm_map_min(kernel_map); 660 if (uvm_map(kernel_map, &addr, (vsize_t)bulk << PAGE_SHIFT, 661 NULL, UVM_UNKNOWN_OFFSET, 0, 662 UVM_MAPFLAG(PROT_READ | PROT_WRITE, 663 PROT_READ | PROT_WRITE, MAP_INHERIT_NONE, 664 MADV_RANDOM, UVM_KMF_TRYLOCK)) != 0) { 665 bulk /= 2; 666 continue; 667 } 668 669 for (i = len; i < len + bulk; i++, addr += PAGE_SIZE) 670 uvm_km_pages.page[i] = addr; 671 len += bulk; 672 } 673 674 uvm_km_pages.free = len; 675 for (i = len; i < UVM_KM_PAGES_HIWAT_MAX; i++) 676 uvm_km_pages.page[i] = 0; 677 678 /* tone down if really high */ 679 if (uvm_km_pages.lowat > 512) 680 uvm_km_pages.lowat = 512; 681 682 kthread_create_deferred(uvm_km_createthread, NULL); 683 } 684 685 void 686 uvm_km_createthread(void *arg) 687 { 688 kthread_create(uvm_km_thread, NULL, &uvm_km_pages.km_proc, "kmthread"); 689 } 690 691 /* 692 * Endless loop. We grab pages in increments of 16 pages, then 693 * quickly swap them into the list. At some point we can consider 694 * returning memory to the system if we have too many free pages, 695 * but that's not implemented yet. 696 */ 697 void 698 uvm_km_thread(void *arg) 699 { 700 vaddr_t pg[16]; 701 int i; 702 int allocmore = 0; 703 int flags; 704 struct uvm_km_free_page *fp = NULL; 705 706 KERNEL_UNLOCK(); 707 708 for (;;) { 709 mtx_enter(&uvm_km_pages.mtx); 710 if (uvm_km_pages.free >= uvm_km_pages.lowat && 711 uvm_km_pages.freelist == NULL) { 712 msleep(&uvm_km_pages.km_proc, &uvm_km_pages.mtx, 713 PVM, "kmalloc", 0); 714 } 715 allocmore = uvm_km_pages.free < uvm_km_pages.lowat; 716 fp = uvm_km_pages.freelist; 717 uvm_km_pages.freelist = NULL; 718 uvm_km_pages.freelistlen = 0; 719 mtx_leave(&uvm_km_pages.mtx); 720 721 if (allocmore) { 722 /* 723 * If there was nothing on the freelist, then we 724 * must obtain at least one page to make progress. 725 * So, only use UVM_KMF_TRYLOCK for the first page 726 * if fp != NULL 727 */ 728 flags = UVM_MAPFLAG(PROT_READ | PROT_WRITE, 729 PROT_READ | PROT_WRITE, MAP_INHERIT_NONE, 730 MADV_RANDOM, fp != NULL ? UVM_KMF_TRYLOCK : 0); 731 memset(pg, 0, sizeof(pg)); 732 for (i = 0; i < nitems(pg); i++) { 733 pg[i] = vm_map_min(kernel_map); 734 if (uvm_map(kernel_map, &pg[i], PAGE_SIZE, 735 NULL, UVM_UNKNOWN_OFFSET, 0, flags) != 0) { 736 pg[i] = 0; 737 break; 738 } 739 740 /* made progress, so don't sleep for more */ 741 flags = UVM_MAPFLAG(PROT_READ | PROT_WRITE, 742 PROT_READ | PROT_WRITE, MAP_INHERIT_NONE, 743 MADV_RANDOM, UVM_KMF_TRYLOCK); 744 } 745 746 mtx_enter(&uvm_km_pages.mtx); 747 for (i = 0; i < nitems(pg); i++) { 748 if (uvm_km_pages.free == 749 nitems(uvm_km_pages.page)) 750 break; 751 else if (pg[i] != 0) 752 uvm_km_pages.page[uvm_km_pages.free++] 753 = pg[i]; 754 } 755 wakeup(&uvm_km_pages.free); 756 mtx_leave(&uvm_km_pages.mtx); 757 758 /* Cleanup left-over pages (if any). */ 759 for (; i < nitems(pg); i++) { 760 if (pg[i] != 0) { 761 uvm_unmap(kernel_map, 762 pg[i], pg[i] + PAGE_SIZE); 763 } 764 } 765 } 766 while (fp) { 767 fp = uvm_km_doputpage(fp); 768 } 769 } 770 } 771 772 struct uvm_km_free_page * 773 uvm_km_doputpage(struct uvm_km_free_page *fp) 774 { 775 vaddr_t va = (vaddr_t)fp; 776 struct vm_page *pg; 777 int freeva = 1; 778 struct uvm_km_free_page *nextfp = fp->next; 779 780 pg = uvm_atopg(va); 781 782 pmap_kremove(va, PAGE_SIZE); 783 pmap_update(kernel_map->pmap); 784 785 mtx_enter(&uvm_km_pages.mtx); 786 if (uvm_km_pages.free < uvm_km_pages.hiwat) { 787 uvm_km_pages.page[uvm_km_pages.free++] = va; 788 freeva = 0; 789 } 790 mtx_leave(&uvm_km_pages.mtx); 791 792 if (freeva) 793 uvm_unmap(kernel_map, va, va + PAGE_SIZE); 794 795 uvm_pagefree(pg); 796 return (nextfp); 797 } 798 #endif /* !__HAVE_PMAP_DIRECT */ 799 800 void * 801 km_alloc(size_t sz, const struct kmem_va_mode *kv, 802 const struct kmem_pa_mode *kp, const struct kmem_dyn_mode *kd) 803 { 804 struct vm_map *map; 805 struct vm_page *pg; 806 struct pglist pgl; 807 int mapflags = 0; 808 vm_prot_t prot; 809 paddr_t pla_align; 810 int pla_flags; 811 int pla_maxseg; 812 vaddr_t va, sva; 813 814 KASSERT(sz == round_page(sz)); 815 816 TAILQ_INIT(&pgl); 817 818 if (kp->kp_nomem || kp->kp_pageable) 819 goto alloc_va; 820 821 pla_flags = kd->kd_waitok ? UVM_PLA_WAITOK : UVM_PLA_NOWAIT; 822 pla_flags |= UVM_PLA_TRYCONTIG; 823 if (kp->kp_zero) 824 pla_flags |= UVM_PLA_ZERO; 825 826 pla_align = kp->kp_align; 827 #ifdef __HAVE_PMAP_DIRECT 828 if (pla_align < kv->kv_align) 829 pla_align = kv->kv_align; 830 #endif 831 pla_maxseg = kp->kp_maxseg; 832 if (pla_maxseg == 0) 833 pla_maxseg = sz / PAGE_SIZE; 834 835 if (uvm_pglistalloc(sz, kp->kp_constraint->ucr_low, 836 kp->kp_constraint->ucr_high, pla_align, kp->kp_boundary, 837 &pgl, pla_maxseg, pla_flags)) { 838 return (NULL); 839 } 840 841 #ifdef __HAVE_PMAP_DIRECT 842 /* 843 * Only use direct mappings for single page or single segment 844 * allocations. 845 */ 846 if (kv->kv_singlepage || kp->kp_maxseg == 1) { 847 TAILQ_FOREACH(pg, &pgl, pageq) { 848 va = pmap_map_direct(pg); 849 if (pg == TAILQ_FIRST(&pgl)) 850 sva = va; 851 } 852 return ((void *)sva); 853 } 854 #endif 855 alloc_va: 856 prot = PROT_READ | PROT_WRITE; 857 858 if (kp->kp_pageable) { 859 KASSERT(kp->kp_object); 860 KASSERT(!kv->kv_singlepage); 861 } else { 862 KASSERT(kp->kp_object == NULL); 863 } 864 865 if (kv->kv_singlepage) { 866 KASSERT(sz == PAGE_SIZE); 867 #ifdef __HAVE_PMAP_DIRECT 868 panic("km_alloc: DIRECT single page"); 869 #else 870 mtx_enter(&uvm_km_pages.mtx); 871 while (uvm_km_pages.free == 0) { 872 if (kd->kd_waitok == 0) { 873 mtx_leave(&uvm_km_pages.mtx); 874 uvm_pglistfree(&pgl); 875 return NULL; 876 } 877 msleep(&uvm_km_pages.free, &uvm_km_pages.mtx, PVM, 878 "getpage", 0); 879 } 880 va = uvm_km_pages.page[--uvm_km_pages.free]; 881 if (uvm_km_pages.free < uvm_km_pages.lowat && 882 curproc != uvm_km_pages.km_proc) { 883 if (kd->kd_slowdown) 884 *kd->kd_slowdown = 1; 885 wakeup(&uvm_km_pages.km_proc); 886 } 887 mtx_leave(&uvm_km_pages.mtx); 888 #endif 889 } else { 890 struct uvm_object *uobj = NULL; 891 892 if (kd->kd_trylock) 893 mapflags |= UVM_KMF_TRYLOCK; 894 895 if (kp->kp_object) 896 uobj = *kp->kp_object; 897 try_map: 898 map = *kv->kv_map; 899 va = vm_map_min(map); 900 if (uvm_map(map, &va, sz, uobj, kd->kd_prefer, 901 kv->kv_align, UVM_MAPFLAG(prot, prot, MAP_INHERIT_NONE, 902 MADV_RANDOM, mapflags))) { 903 if (kv->kv_wait && kd->kd_waitok) { 904 tsleep(map, PVM, "km_allocva", 0); 905 goto try_map; 906 } 907 uvm_pglistfree(&pgl); 908 return (NULL); 909 } 910 } 911 sva = va; 912 TAILQ_FOREACH(pg, &pgl, pageq) { 913 if (kp->kp_pageable) 914 pmap_enter(pmap_kernel(), va, VM_PAGE_TO_PHYS(pg), 915 prot, prot | PMAP_WIRED); 916 else 917 pmap_kenter_pa(va, VM_PAGE_TO_PHYS(pg), prot); 918 va += PAGE_SIZE; 919 } 920 pmap_update(pmap_kernel()); 921 return ((void *)sva); 922 } 923 924 void 925 km_free(void *v, size_t sz, const struct kmem_va_mode *kv, 926 const struct kmem_pa_mode *kp) 927 { 928 vaddr_t sva, eva, va; 929 struct vm_page *pg; 930 struct pglist pgl; 931 932 sva = (vaddr_t)v; 933 eva = sva + sz; 934 935 if (kp->kp_nomem) 936 goto free_va; 937 938 #ifdef __HAVE_PMAP_DIRECT 939 if (kv->kv_singlepage || kp->kp_maxseg == 1) { 940 TAILQ_INIT(&pgl); 941 for (va = sva; va < eva; va += PAGE_SIZE) { 942 pg = pmap_unmap_direct(va); 943 TAILQ_INSERT_TAIL(&pgl, pg, pageq); 944 } 945 uvm_pglistfree(&pgl); 946 return; 947 } 948 #else 949 if (kv->kv_singlepage) { 950 struct uvm_km_free_page *fp = v; 951 952 mtx_enter(&uvm_km_pages.mtx); 953 fp->next = uvm_km_pages.freelist; 954 uvm_km_pages.freelist = fp; 955 if (uvm_km_pages.freelistlen++ > 16) 956 wakeup(&uvm_km_pages.km_proc); 957 mtx_leave(&uvm_km_pages.mtx); 958 return; 959 } 960 #endif 961 962 if (kp->kp_pageable) { 963 pmap_remove(pmap_kernel(), sva, eva); 964 pmap_update(pmap_kernel()); 965 } else { 966 TAILQ_INIT(&pgl); 967 for (va = sva; va < eva; va += PAGE_SIZE) { 968 paddr_t pa; 969 970 if (!pmap_extract(pmap_kernel(), va, &pa)) 971 continue; 972 973 pg = PHYS_TO_VM_PAGE(pa); 974 if (pg == NULL) { 975 panic("km_free: unmanaged page 0x%lx\n", pa); 976 } 977 TAILQ_INSERT_TAIL(&pgl, pg, pageq); 978 } 979 pmap_kremove(sva, sz); 980 pmap_update(pmap_kernel()); 981 uvm_pglistfree(&pgl); 982 } 983 free_va: 984 uvm_unmap(*kv->kv_map, sva, eva); 985 if (kv->kv_wait) 986 wakeup(*kv->kv_map); 987 } 988 989 const struct kmem_va_mode kv_any = { 990 .kv_map = &kernel_map, 991 }; 992 993 const struct kmem_va_mode kv_intrsafe = { 994 .kv_map = &kmem_map, 995 }; 996 997 const struct kmem_va_mode kv_page = { 998 .kv_singlepage = 1 999 }; 1000 1001 const struct kmem_pa_mode kp_dirty = { 1002 .kp_constraint = &no_constraint 1003 }; 1004 1005 const struct kmem_pa_mode kp_dma = { 1006 .kp_constraint = &dma_constraint 1007 }; 1008 1009 const struct kmem_pa_mode kp_dma_contig = { 1010 .kp_constraint = &dma_constraint, 1011 .kp_maxseg = 1 1012 }; 1013 1014 const struct kmem_pa_mode kp_dma_zero = { 1015 .kp_constraint = &dma_constraint, 1016 .kp_zero = 1 1017 }; 1018 1019 const struct kmem_pa_mode kp_zero = { 1020 .kp_constraint = &no_constraint, 1021 .kp_zero = 1 1022 }; 1023 1024 const struct kmem_pa_mode kp_pageable = { 1025 .kp_object = &uvm.kernel_object, 1026 .kp_pageable = 1 1027 /* XXX - kp_nomem, maybe, but we'll need to fix km_free. */ 1028 }; 1029 1030 const struct kmem_pa_mode kp_none = { 1031 .kp_nomem = 1 1032 }; 1033 1034 const struct kmem_dyn_mode kd_waitok = { 1035 .kd_waitok = 1, 1036 .kd_prefer = UVM_UNKNOWN_OFFSET 1037 }; 1038 1039 const struct kmem_dyn_mode kd_nowait = { 1040 .kd_prefer = UVM_UNKNOWN_OFFSET 1041 }; 1042 1043 const struct kmem_dyn_mode kd_trylock = { 1044 .kd_trylock = 1, 1045 .kd_prefer = UVM_UNKNOWN_OFFSET 1046 }; 1047