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 * %sccs.include.redist.c% 9 * 10 * @(#)vm_kern.c 8.3 (Berkeley) 01/12/94 11 * 12 * 13 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 14 * All rights reserved. 15 * 16 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 17 * 18 * Permission to use, copy, modify and distribute this software and 19 * its documentation is hereby granted, provided that both the copyright 20 * notice and this permission notice appear in all copies of the 21 * software, derivative works or modified versions, and any portions 22 * thereof, and that both notices appear in supporting documentation. 23 * 24 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 25 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 26 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 27 * 28 * Carnegie Mellon requests users of this software to return to 29 * 30 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 31 * School of Computer Science 32 * Carnegie Mellon University 33 * Pittsburgh PA 15213-3890 34 * 35 * any improvements or extensions that they make and grant Carnegie the 36 * rights to redistribute these changes. 37 */ 38 39 /* 40 * Kernel memory management. 41 */ 42 43 #include <sys/param.h> 44 #include <sys/systm.h> 45 46 #include <vm/vm.h> 47 #include <vm/vm_page.h> 48 #include <vm/vm_pageout.h> 49 #include <vm/vm_kern.h> 50 51 /* 52 * kmem_alloc_pageable: 53 * 54 * Allocate pageable memory to the kernel's address map. 55 * map must be "kernel_map" below. 56 */ 57 58 vm_offset_t kmem_alloc_pageable(map, size) 59 vm_map_t map; 60 register vm_size_t size; 61 { 62 vm_offset_t addr; 63 register int result; 64 65 #if 0 66 if (map != kernel_map) 67 panic("kmem_alloc_pageable: not called with kernel_map"); 68 #endif 69 70 size = round_page(size); 71 72 addr = vm_map_min(map); 73 result = vm_map_find(map, NULL, (vm_offset_t) 0, 74 &addr, size, TRUE); 75 if (result != KERN_SUCCESS) { 76 return(0); 77 } 78 79 return(addr); 80 } 81 82 /* 83 * Allocate wired-down memory in the kernel's address map 84 * or a submap. 85 */ 86 vm_offset_t kmem_alloc(map, size) 87 register vm_map_t map; 88 register vm_size_t size; 89 { 90 vm_offset_t addr; 91 register vm_offset_t offset; 92 extern vm_object_t kernel_object; 93 vm_offset_t i; 94 95 size = round_page(size); 96 97 /* 98 * Use the kernel object for wired-down kernel pages. 99 * Assume that no region of the kernel object is 100 * referenced more than once. 101 */ 102 103 /* 104 * Locate sufficient space in the map. This will give us the 105 * final virtual address for the new memory, and thus will tell 106 * us the offset within the kernel map. 107 */ 108 vm_map_lock(map); 109 if (vm_map_findspace(map, 0, size, &addr)) { 110 vm_map_unlock(map); 111 return (0); 112 } 113 offset = addr - VM_MIN_KERNEL_ADDRESS; 114 vm_object_reference(kernel_object); 115 vm_map_insert(map, kernel_object, offset, addr, addr + size); 116 vm_map_unlock(map); 117 118 /* 119 * Guarantee that there are pages already in this object 120 * before calling vm_map_pageable. This is to prevent the 121 * following scenario: 122 * 123 * 1) Threads have swapped out, so that there is a 124 * pager for the kernel_object. 125 * 2) The kmsg zone is empty, and so we are kmem_allocing 126 * a new page for it. 127 * 3) vm_map_pageable calls vm_fault; there is no page, 128 * but there is a pager, so we call 129 * pager_data_request. But the kmsg zone is empty, 130 * so we must kmem_alloc. 131 * 4) goto 1 132 * 5) Even if the kmsg zone is not empty: when we get 133 * the data back from the pager, it will be (very 134 * stale) non-zero data. kmem_alloc is defined to 135 * return zero-filled memory. 136 * 137 * We're intentionally not activating the pages we allocate 138 * to prevent a race with page-out. vm_map_pageable will wire 139 * the pages. 140 */ 141 142 vm_object_lock(kernel_object); 143 for (i = 0 ; i < size; i+= PAGE_SIZE) { 144 vm_page_t mem; 145 146 while ((mem = vm_page_alloc(kernel_object, offset+i)) == NULL) { 147 vm_object_unlock(kernel_object); 148 VM_WAIT; 149 vm_object_lock(kernel_object); 150 } 151 vm_page_zero_fill(mem); 152 mem->flags &= ~PG_BUSY; 153 } 154 vm_object_unlock(kernel_object); 155 156 /* 157 * And finally, mark the data as non-pageable. 158 */ 159 160 (void) vm_map_pageable(map, (vm_offset_t) addr, addr + size, FALSE); 161 162 /* 163 * Try to coalesce the map 164 */ 165 166 vm_map_simplify(map, addr); 167 168 return(addr); 169 } 170 171 /* 172 * kmem_free: 173 * 174 * Release a region of kernel virtual memory allocated 175 * with kmem_alloc, and return the physical pages 176 * associated with that region. 177 */ 178 void kmem_free(map, addr, size) 179 vm_map_t map; 180 register vm_offset_t addr; 181 vm_size_t size; 182 { 183 (void) vm_map_remove(map, trunc_page(addr), round_page(addr + size)); 184 } 185 186 /* 187 * kmem_suballoc: 188 * 189 * Allocates a map to manage a subrange 190 * of the kernel virtual address space. 191 * 192 * Arguments are as follows: 193 * 194 * parent Map to take range from 195 * size Size of range to find 196 * min, max Returned endpoints of map 197 * pageable Can the region be paged 198 */ 199 vm_map_t kmem_suballoc(parent, min, max, size, pageable) 200 register vm_map_t parent; 201 vm_offset_t *min, *max; 202 register vm_size_t size; 203 boolean_t pageable; 204 { 205 register int ret; 206 vm_map_t result; 207 208 size = round_page(size); 209 210 *min = (vm_offset_t) vm_map_min(parent); 211 ret = vm_map_find(parent, NULL, (vm_offset_t) 0, 212 min, size, TRUE); 213 if (ret != KERN_SUCCESS) { 214 printf("kmem_suballoc: bad status return of %d.\n", ret); 215 panic("kmem_suballoc"); 216 } 217 *max = *min + size; 218 pmap_reference(vm_map_pmap(parent)); 219 result = vm_map_create(vm_map_pmap(parent), *min, *max, pageable); 220 if (result == NULL) 221 panic("kmem_suballoc: cannot create submap"); 222 if ((ret = vm_map_submap(parent, *min, *max, result)) != KERN_SUCCESS) 223 panic("kmem_suballoc: unable to change range to submap"); 224 return(result); 225 } 226 227 /* 228 * Allocate wired-down memory in the kernel's address map for the higher 229 * level kernel memory allocator (kern/kern_malloc.c). We cannot use 230 * kmem_alloc() because we may need to allocate memory at interrupt 231 * level where we cannot block (canwait == FALSE). 232 * 233 * This routine has its own private kernel submap (kmem_map) and object 234 * (kmem_object). This, combined with the fact that only malloc uses 235 * this routine, ensures that we will never block in map or object waits. 236 * 237 * Note that this still only works in a uni-processor environment and 238 * when called at splhigh(). 239 * 240 * We don't worry about expanding the map (adding entries) since entries 241 * for wired maps are statically allocated. 242 */ 243 vm_offset_t 244 kmem_malloc(map, size, canwait) 245 register vm_map_t map; 246 register vm_size_t size; 247 boolean_t canwait; 248 { 249 register vm_offset_t offset, i; 250 vm_map_entry_t entry; 251 vm_offset_t addr; 252 vm_page_t m; 253 extern vm_object_t kmem_object; 254 255 if (map != kmem_map && map != mb_map) 256 panic("kern_malloc_alloc: map != {kmem,mb}_map"); 257 258 size = round_page(size); 259 addr = vm_map_min(map); 260 261 /* 262 * Locate sufficient space in the map. This will give us the 263 * final virtual address for the new memory, and thus will tell 264 * us the offset within the kernel map. 265 */ 266 vm_map_lock(map); 267 if (vm_map_findspace(map, 0, size, &addr)) { 268 vm_map_unlock(map); 269 if (canwait) /* XXX should wait */ 270 panic("kmem_malloc: %s too small", 271 map == kmem_map ? "kmem_map" : "mb_map"); 272 return (0); 273 } 274 offset = addr - vm_map_min(kmem_map); 275 vm_object_reference(kmem_object); 276 vm_map_insert(map, kmem_object, offset, addr, addr + size); 277 278 /* 279 * If we can wait, just mark the range as wired 280 * (will fault pages as necessary). 281 */ 282 if (canwait) { 283 vm_map_unlock(map); 284 (void) vm_map_pageable(map, (vm_offset_t) addr, addr + size, 285 FALSE); 286 vm_map_simplify(map, addr); 287 return(addr); 288 } 289 290 /* 291 * If we cannot wait then we must allocate all memory up front, 292 * pulling it off the active queue to prevent pageout. 293 */ 294 vm_object_lock(kmem_object); 295 for (i = 0; i < size; i += PAGE_SIZE) { 296 m = vm_page_alloc(kmem_object, offset + i); 297 298 /* 299 * Ran out of space, free everything up and return. 300 * Don't need to lock page queues here as we know 301 * that the pages we got aren't on any queues. 302 */ 303 if (m == NULL) { 304 while (i != 0) { 305 i -= PAGE_SIZE; 306 m = vm_page_lookup(kmem_object, offset + i); 307 vm_page_free(m); 308 } 309 vm_object_unlock(kmem_object); 310 vm_map_delete(map, addr, addr + size); 311 vm_map_unlock(map); 312 return(0); 313 } 314 #if 0 315 vm_page_zero_fill(m); 316 #endif 317 m->flags &= ~PG_BUSY; 318 } 319 vm_object_unlock(kmem_object); 320 321 /* 322 * Mark map entry as non-pageable. 323 * Assert: vm_map_insert() will never be able to extend the previous 324 * entry so there will be a new entry exactly corresponding to this 325 * address range and it will have wired_count == 0. 326 */ 327 if (!vm_map_lookup_entry(map, addr, &entry) || 328 entry->start != addr || entry->end != addr + size || 329 entry->wired_count) 330 panic("kmem_malloc: entry not found or misaligned"); 331 entry->wired_count++; 332 333 /* 334 * Loop thru pages, entering them in the pmap. 335 * (We cannot add them to the wired count without 336 * wrapping the vm_page_queue_lock in splimp...) 337 */ 338 for (i = 0; i < size; i += PAGE_SIZE) { 339 vm_object_lock(kmem_object); 340 m = vm_page_lookup(kmem_object, offset + i); 341 vm_object_unlock(kmem_object); 342 pmap_enter(map->pmap, addr + i, VM_PAGE_TO_PHYS(m), 343 VM_PROT_DEFAULT, TRUE); 344 } 345 vm_map_unlock(map); 346 347 vm_map_simplify(map, addr); 348 return(addr); 349 } 350 351 /* 352 * kmem_alloc_wait 353 * 354 * Allocates pageable memory from a sub-map of the kernel. If the submap 355 * has no room, the caller sleeps waiting for more memory in the submap. 356 * 357 */ 358 vm_offset_t kmem_alloc_wait(map, size) 359 vm_map_t map; 360 vm_size_t size; 361 { 362 vm_offset_t addr; 363 364 size = round_page(size); 365 366 for (;;) { 367 /* 368 * To make this work for more than one map, 369 * use the map's lock to lock out sleepers/wakers. 370 */ 371 vm_map_lock(map); 372 if (vm_map_findspace(map, 0, size, &addr) == 0) 373 break; 374 /* no space now; see if we can ever get space */ 375 if (vm_map_max(map) - vm_map_min(map) < size) { 376 vm_map_unlock(map); 377 return (0); 378 } 379 assert_wait((int)map, TRUE); 380 vm_map_unlock(map); 381 thread_block(); 382 } 383 vm_map_insert(map, NULL, (vm_offset_t)0, addr, addr + size); 384 vm_map_unlock(map); 385 return (addr); 386 } 387 388 /* 389 * kmem_free_wakeup 390 * 391 * Returns memory to a submap of the kernel, and wakes up any threads 392 * waiting for memory in that map. 393 */ 394 void kmem_free_wakeup(map, addr, size) 395 vm_map_t map; 396 vm_offset_t addr; 397 vm_size_t size; 398 { 399 vm_map_lock(map); 400 (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size)); 401 thread_wakeup((int)map); 402 vm_map_unlock(map); 403 } 404 405 /* 406 * Create the kernel map; insert a mapping covering kernel text, data, bss, 407 * and all space allocated thus far (`boostrap' data). The new map will thus 408 * map the range between VM_MIN_KERNEL_ADDRESS and `start' as allocated, and 409 * the range between `start' and `end' as free. 410 */ 411 void kmem_init(start, end) 412 vm_offset_t start, end; 413 { 414 register vm_map_t m; 415 416 m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end, FALSE); 417 vm_map_lock(m); 418 /* N.B.: cannot use kgdb to debug, starting with this assignment ... */ 419 kernel_map = m; 420 (void) vm_map_insert(m, NULL, (vm_offset_t)0, 421 VM_MIN_KERNEL_ADDRESS, start); 422 /* ... and ending with the completion of the above `insert' */ 423 vm_map_unlock(m); 424 } 425