vm_kern.c revision 1542
1/* 2 * Copyright (c) 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software contributed to Berkeley by 6 * The Mach Operating System project at Carnegie-Mellon University. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)vm_kern.c 8.3 (Berkeley) 1/12/94 37 * 38 * 39 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 40 * All rights reserved. 41 * 42 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 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 * Kernel memory management. 67 */ 68 69#include <sys/param.h> 70#include <sys/systm.h> 71 72#include <vm/vm.h> 73#include <vm/vm_page.h> 74#include <vm/vm_pageout.h> 75#include <vm/vm_kern.h> 76 77/* 78 * kmem_alloc_pageable: 79 * 80 * Allocate pageable memory to the kernel's address map. 81 * map must be "kernel_map" below. 82 */ 83 84vm_offset_t kmem_alloc_pageable(map, size) 85 vm_map_t map; 86 register vm_size_t size; 87{ 88 vm_offset_t addr; 89 register int result; 90 91#if 0 92 if (map != kernel_map) 93 panic("kmem_alloc_pageable: not called with kernel_map"); 94#endif 95 96 size = round_page(size); 97 98 addr = vm_map_min(map); 99 result = vm_map_find(map, NULL, (vm_offset_t) 0, 100 &addr, size, TRUE); 101 if (result != KERN_SUCCESS) { 102 return(0); 103 } 104 105 return(addr); 106} 107 108/* 109 * Allocate wired-down memory in the kernel's address map 110 * or a submap. 111 */ 112vm_offset_t kmem_alloc(map, size) 113 register vm_map_t map; 114 register vm_size_t size; 115{ 116 vm_offset_t addr; 117 register vm_offset_t offset; 118 extern vm_object_t kernel_object; 119 vm_offset_t i; 120 121 size = round_page(size); 122 123 /* 124 * Use the kernel object for wired-down kernel pages. 125 * Assume that no region of the kernel object is 126 * referenced more than once. 127 */ 128 129 /* 130 * Locate sufficient space in the map. This will give us the 131 * final virtual address for the new memory, and thus will tell 132 * us the offset within the kernel map. 133 */ 134 vm_map_lock(map); 135 if (vm_map_findspace(map, 0, size, &addr)) { 136 vm_map_unlock(map); 137 return (0); 138 } 139 offset = addr - VM_MIN_KERNEL_ADDRESS; 140 vm_object_reference(kernel_object); 141 vm_map_insert(map, kernel_object, offset, addr, addr + size); 142 vm_map_unlock(map); 143 144 /* 145 * Guarantee that there are pages already in this object 146 * before calling vm_map_pageable. This is to prevent the 147 * following scenario: 148 * 149 * 1) Threads have swapped out, so that there is a 150 * pager for the kernel_object. 151 * 2) The kmsg zone is empty, and so we are kmem_allocing 152 * a new page for it. 153 * 3) vm_map_pageable calls vm_fault; there is no page, 154 * but there is a pager, so we call 155 * pager_data_request. But the kmsg zone is empty, 156 * so we must kmem_alloc. 157 * 4) goto 1 158 * 5) Even if the kmsg zone is not empty: when we get 159 * the data back from the pager, it will be (very 160 * stale) non-zero data. kmem_alloc is defined to 161 * return zero-filled memory. 162 * 163 * We're intentionally not activating the pages we allocate 164 * to prevent a race with page-out. vm_map_pageable will wire 165 * the pages. 166 */ 167 168 vm_object_lock(kernel_object); 169 for (i = 0 ; i < size; i+= PAGE_SIZE) { 170 vm_page_t mem; 171 172 while ((mem = vm_page_alloc(kernel_object, offset+i)) == NULL) { 173 vm_object_unlock(kernel_object); 174 VM_WAIT; 175 vm_object_lock(kernel_object); 176 } 177 vm_page_zero_fill(mem); 178 mem->flags &= ~PG_BUSY; 179 } 180 vm_object_unlock(kernel_object); 181 182 /* 183 * And finally, mark the data as non-pageable. 184 */ 185 186 (void) vm_map_pageable(map, (vm_offset_t) addr, addr + size, FALSE); 187 188 /* 189 * Try to coalesce the map 190 */ 191 192 vm_map_simplify(map, addr); 193 194 return(addr); 195} 196 197/* 198 * kmem_free: 199 * 200 * Release a region of kernel virtual memory allocated 201 * with kmem_alloc, and return the physical pages 202 * associated with that region. 203 */ 204void kmem_free(map, addr, size) 205 vm_map_t map; 206 register vm_offset_t addr; 207 vm_size_t size; 208{ 209 (void) vm_map_remove(map, trunc_page(addr), round_page(addr + size)); 210} 211 212/* 213 * kmem_suballoc: 214 * 215 * Allocates a map to manage a subrange 216 * of the kernel virtual address space. 217 * 218 * Arguments are as follows: 219 * 220 * parent Map to take range from 221 * size Size of range to find 222 * min, max Returned endpoints of map 223 * pageable Can the region be paged 224 */ 225vm_map_t kmem_suballoc(parent, min, max, size, pageable) 226 register vm_map_t parent; 227 vm_offset_t *min, *max; 228 register vm_size_t size; 229 boolean_t pageable; 230{ 231 register int ret; 232 vm_map_t result; 233 234 size = round_page(size); 235 236 *min = (vm_offset_t) vm_map_min(parent); 237 ret = vm_map_find(parent, NULL, (vm_offset_t) 0, 238 min, size, TRUE); 239 if (ret != KERN_SUCCESS) { 240 printf("kmem_suballoc: bad status return of %d.\n", ret); 241 panic("kmem_suballoc"); 242 } 243 *max = *min + size; 244 pmap_reference(vm_map_pmap(parent)); 245 result = vm_map_create(vm_map_pmap(parent), *min, *max, pageable); 246 if (result == NULL) 247 panic("kmem_suballoc: cannot create submap"); 248 if ((ret = vm_map_submap(parent, *min, *max, result)) != KERN_SUCCESS) 249 panic("kmem_suballoc: unable to change range to submap"); 250 return(result); 251} 252 253/* 254 * Allocate wired-down memory in the kernel's address map for the higher 255 * level kernel memory allocator (kern/kern_malloc.c). We cannot use 256 * kmem_alloc() because we may need to allocate memory at interrupt 257 * level where we cannot block (canwait == FALSE). 258 * 259 * This routine has its own private kernel submap (kmem_map) and object 260 * (kmem_object). This, combined with the fact that only malloc uses 261 * this routine, ensures that we will never block in map or object waits. 262 * 263 * Note that this still only works in a uni-processor environment and 264 * when called at splhigh(). 265 * 266 * We don't worry about expanding the map (adding entries) since entries 267 * for wired maps are statically allocated. 268 */ 269vm_offset_t 270kmem_malloc(map, size, canwait) 271 register vm_map_t map; 272 register vm_size_t size; 273 boolean_t canwait; 274{ 275 register vm_offset_t offset, i; 276 vm_map_entry_t entry; 277 vm_offset_t addr; 278 vm_page_t m; 279 extern vm_object_t kmem_object; 280 281 if (map != kmem_map && map != mb_map) 282 panic("kern_malloc_alloc: map != {kmem,mb}_map"); 283 284 size = round_page(size); 285 addr = vm_map_min(map); 286 287 /* 288 * Locate sufficient space in the map. This will give us the 289 * final virtual address for the new memory, and thus will tell 290 * us the offset within the kernel map. 291 */ 292 vm_map_lock(map); 293 if (vm_map_findspace(map, 0, size, &addr)) { 294 vm_map_unlock(map); 295 if (canwait) /* XXX should wait */ 296 panic("kmem_malloc: %s too small", 297 map == kmem_map ? "kmem_map" : "mb_map"); 298 return (0); 299 } 300 offset = addr - vm_map_min(kmem_map); 301 vm_object_reference(kmem_object); 302 vm_map_insert(map, kmem_object, offset, addr, addr + size); 303 304 /* 305 * If we can wait, just mark the range as wired 306 * (will fault pages as necessary). 307 */ 308 if (canwait) { 309 vm_map_unlock(map); 310 (void) vm_map_pageable(map, (vm_offset_t) addr, addr + size, 311 FALSE); 312 vm_map_simplify(map, addr); 313 return(addr); 314 } 315 316 /* 317 * If we cannot wait then we must allocate all memory up front, 318 * pulling it off the active queue to prevent pageout. 319 */ 320 vm_object_lock(kmem_object); 321 for (i = 0; i < size; i += PAGE_SIZE) { 322 m = vm_page_alloc(kmem_object, offset + i); 323 324 /* 325 * Ran out of space, free everything up and return. 326 * Don't need to lock page queues here as we know 327 * that the pages we got aren't on any queues. 328 */ 329 if (m == NULL) { 330 while (i != 0) { 331 i -= PAGE_SIZE; 332 m = vm_page_lookup(kmem_object, offset + i); 333 vm_page_free(m); 334 } 335 vm_object_unlock(kmem_object); 336 vm_map_delete(map, addr, addr + size); 337 vm_map_unlock(map); 338 return(0); 339 } 340#if 0 341 vm_page_zero_fill(m); 342#endif 343 m->flags &= ~PG_BUSY; 344 } 345 vm_object_unlock(kmem_object); 346 347 /* 348 * Mark map entry as non-pageable. 349 * Assert: vm_map_insert() will never be able to extend the previous 350 * entry so there will be a new entry exactly corresponding to this 351 * address range and it will have wired_count == 0. 352 */ 353 if (!vm_map_lookup_entry(map, addr, &entry) || 354 entry->start != addr || entry->end != addr + size || 355 entry->wired_count) 356 panic("kmem_malloc: entry not found or misaligned"); 357 entry->wired_count++; 358 359 /* 360 * Loop thru pages, entering them in the pmap. 361 * (We cannot add them to the wired count without 362 * wrapping the vm_page_queue_lock in splimp...) 363 */ 364 for (i = 0; i < size; i += PAGE_SIZE) { 365 vm_object_lock(kmem_object); 366 m = vm_page_lookup(kmem_object, offset + i); 367 vm_object_unlock(kmem_object); 368 pmap_enter(map->pmap, addr + i, VM_PAGE_TO_PHYS(m), 369 VM_PROT_DEFAULT, TRUE); 370 } 371 vm_map_unlock(map); 372 373 vm_map_simplify(map, addr); 374 return(addr); 375} 376 377/* 378 * kmem_alloc_wait 379 * 380 * Allocates pageable memory from a sub-map of the kernel. If the submap 381 * has no room, the caller sleeps waiting for more memory in the submap. 382 * 383 */ 384vm_offset_t kmem_alloc_wait(map, size) 385 vm_map_t map; 386 vm_size_t size; 387{ 388 vm_offset_t addr; 389 390 size = round_page(size); 391 392 for (;;) { 393 /* 394 * To make this work for more than one map, 395 * use the map's lock to lock out sleepers/wakers. 396 */ 397 vm_map_lock(map); 398 if (vm_map_findspace(map, 0, size, &addr) == 0) 399 break; 400 /* no space now; see if we can ever get space */ 401 if (vm_map_max(map) - vm_map_min(map) < size) { 402 vm_map_unlock(map); 403 return (0); 404 } 405 assert_wait((int)map, TRUE); 406 vm_map_unlock(map); 407 thread_block(); 408 } 409 vm_map_insert(map, NULL, (vm_offset_t)0, addr, addr + size); 410 vm_map_unlock(map); 411 return (addr); 412} 413 414/* 415 * kmem_free_wakeup 416 * 417 * Returns memory to a submap of the kernel, and wakes up any threads 418 * waiting for memory in that map. 419 */ 420void kmem_free_wakeup(map, addr, size) 421 vm_map_t map; 422 vm_offset_t addr; 423 vm_size_t size; 424{ 425 vm_map_lock(map); 426 (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size)); 427 thread_wakeup((int)map); 428 vm_map_unlock(map); 429} 430 431/* 432 * Create the kernel map; insert a mapping covering kernel text, data, bss, 433 * and all space allocated thus far (`boostrap' data). The new map will thus 434 * map the range between VM_MIN_KERNEL_ADDRESS and `start' as allocated, and 435 * the range between `start' and `end' as free. 436 */ 437void kmem_init(start, end) 438 vm_offset_t start, end; 439{ 440 register vm_map_t m; 441 442 m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end, FALSE); 443 vm_map_lock(m); 444 /* N.B.: cannot use kgdb to debug, starting with this assignment ... */ 445 kernel_map = m; 446 (void) vm_map_insert(m, NULL, (vm_offset_t)0, 447 VM_MIN_KERNEL_ADDRESS, start); 448 /* ... and ending with the completion of the above `insert' */ 449 vm_map_unlock(m); 450} 451