Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_kern.c
Version:
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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 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * from: @(#)vm_kern.c 8.3 (Berkeley) 1/12/94 33 * 34 * 35 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 36 * All rights reserved. 37 * 38 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 39 * 40 * Permission to use, copy, modify and distribute this software and 41 * its documentation is hereby granted, provided that both the copyright 42 * notice and this permission notice appear in all copies of the 43 * software, derivative works or modified versions, and any portions 44 * thereof, and that both notices appear in supporting documentation. 45 * 46 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 47 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 48 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 49 * 50 * Carnegie Mellon requests users of this software to return to 51 * 52 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 53 * School of Computer Science 54 * Carnegie Mellon University 55 * Pittsburgh PA 15213-3890 56 * 57 * any improvements or extensions that they make and grant Carnegie the 58 * rights to redistribute these changes. 59 */ 60 61 /* 62 * Kernel memory management. 63 */ 64 65 #include <sys/cdefs.h> 66 __FBSDID("$FreeBSD: releng/11.2/sys/vm/vm_kern.c 331722 2018-03-29 02:50:57Z eadler $"); 67 68 #include <sys/param.h> 69 #include <sys/systm.h> 70 #include <sys/kernel.h> /* for ticks and hz */ 71 #include <sys/eventhandler.h> 72 #include <sys/lock.h> 73 #include <sys/proc.h> 74 #include <sys/malloc.h> 75 #include <sys/rwlock.h> 76 #include <sys/sysctl.h> 77 #include <sys/vmem.h> 78 79 #include <vm/vm.h> 80 #include <vm/vm_param.h> 81 #include <vm/vm_kern.h> 82 #include <vm/pmap.h> 83 #include <vm/vm_map.h> 84 #include <vm/vm_object.h> 85 #include <vm/vm_page.h> 86 #include <vm/vm_pageout.h> 87 #include <vm/vm_radix.h> 88 #include <vm/vm_extern.h> 89 #include <vm/uma.h> 90 91 vm_map_t kernel_map; 92 vm_map_t exec_map; 93 vm_map_t pipe_map; 94 95 const void *zero_region; 96 CTASSERT((ZERO_REGION_SIZE & PAGE_MASK) == 0); 97 98 /* NB: Used by kernel debuggers. */ 99 const u_long vm_maxuser_address = VM_MAXUSER_ADDRESS; 100 101 u_int exec_map_entry_size; 102 u_int exec_map_entries; 103 104 SYSCTL_ULONG(_vm, OID_AUTO, min_kernel_address, CTLFLAG_RD, 105 SYSCTL_NULL_ULONG_PTR, VM_MIN_KERNEL_ADDRESS, "Min kernel address"); 106 107 SYSCTL_ULONG(_vm, OID_AUTO, max_kernel_address, CTLFLAG_RD, 108 #if defined(__arm__) || defined(__sparc64__) 109 &vm_max_kernel_address, 0, 110 #else 111 SYSCTL_NULL_ULONG_PTR, VM_MAX_KERNEL_ADDRESS, 112 #endif 113 "Max kernel address"); 114 115 /* 116 * kva_alloc: 117 * 118 * Allocate a virtual address range with no underlying object and 119 * no initial mapping to physical memory. Any mapping from this 120 * range to physical memory must be explicitly created prior to 121 * its use, typically with pmap_qenter(). Any attempt to create 122 * a mapping on demand through vm_fault() will result in a panic. 123 */ 124 vm_offset_t 125 kva_alloc(vm_size_t size) 126 { 127 vm_offset_t addr; 128 129 size = round_page(size); 130 if (vmem_alloc(kernel_arena, size, M_BESTFIT | M_NOWAIT, &addr)) 131 return (0); 132 133 return (addr); 134 } 135 136 /* 137 * kva_free: 138 * 139 * Release a region of kernel virtual memory allocated 140 * with kva_alloc, and return the physical pages 141 * associated with that region. 142 * 143 * This routine may not block on kernel maps. 144 */ 145 void 146 kva_free(vm_offset_t addr, vm_size_t size) 147 { 148 149 size = round_page(size); 150 vmem_free(kernel_arena, addr, size); 151 } 152 153 /* 154 * Allocates a region from the kernel address map and physical pages 155 * within the specified address range to the kernel object. Creates a 156 * wired mapping from this region to these pages, and returns the 157 * region's starting virtual address. The allocated pages are not 158 * necessarily physically contiguous. If M_ZERO is specified through the 159 * given flags, then the pages are zeroed before they are mapped. 160 */ 161 vm_offset_t 162 kmem_alloc_attr(vmem_t *vmem, vm_size_t size, int flags, vm_paddr_t low, 163 vm_paddr_t high, vm_memattr_t memattr) 164 { 165 vm_object_t object = vmem == kmem_arena ? kmem_object : kernel_object; 166 vm_offset_t addr, i, offset; 167 vm_page_t m; 168 int pflags, tries; 169 170 size = round_page(size); 171 if (vmem_alloc(vmem, size, M_BESTFIT | flags, &addr)) 172 return (0); 173 offset = addr - VM_MIN_KERNEL_ADDRESS; 174 pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED; 175 pflags &= ~(VM_ALLOC_NOWAIT | VM_ALLOC_WAITOK | VM_ALLOC_WAITFAIL); 176 pflags |= VM_ALLOC_NOWAIT; 177 VM_OBJECT_WLOCK(object); 178 for (i = 0; i < size; i += PAGE_SIZE) { 179 tries = 0; 180 retry: 181 m = vm_page_alloc_contig(object, atop(offset + i), 182 pflags, 1, low, high, PAGE_SIZE, 0, memattr); 183 if (m == NULL) { 184 VM_OBJECT_WUNLOCK(object); 185 if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) { 186 if (!vm_page_reclaim_contig(pflags, 1, 187 low, high, PAGE_SIZE, 0) && 188 (flags & M_WAITOK) != 0) 189 VM_WAIT; 190 VM_OBJECT_WLOCK(object); 191 tries++; 192 goto retry; 193 } 194 kmem_unback(object, addr, i); 195 vmem_free(vmem, addr, size); 196 return (0); 197 } 198 if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0) 199 pmap_zero_page(m); 200 m->valid = VM_PAGE_BITS_ALL; 201 pmap_enter(kernel_pmap, addr + i, m, VM_PROT_ALL, 202 VM_PROT_ALL | PMAP_ENTER_WIRED, 0); 203 } 204 VM_OBJECT_WUNLOCK(object); 205 return (addr); 206 } 207 208 /* 209 * Allocates a region from the kernel address map and physically 210 * contiguous pages within the specified address range to the kernel 211 * object. Creates a wired mapping from this region to these pages, and 212 * returns the region's starting virtual address. If M_ZERO is specified 213 * through the given flags, then the pages are zeroed before they are 214 * mapped. 215 */ 216 vm_offset_t 217 kmem_alloc_contig(struct vmem *vmem, vm_size_t size, int flags, vm_paddr_t low, 218 vm_paddr_t high, u_long alignment, vm_paddr_t boundary, 219 vm_memattr_t memattr) 220 { 221 vm_object_t object = vmem == kmem_arena ? kmem_object : kernel_object; 222 vm_offset_t addr, offset, tmp; 223 vm_page_t end_m, m; 224 u_long npages; 225 int pflags, tries; 226 227 size = round_page(size); 228 if (vmem_alloc(vmem, size, flags | M_BESTFIT, &addr)) 229 return (0); 230 offset = addr - VM_MIN_KERNEL_ADDRESS; 231 pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED; 232 pflags &= ~(VM_ALLOC_NOWAIT | VM_ALLOC_WAITOK | VM_ALLOC_WAITFAIL); 233 pflags |= VM_ALLOC_NOWAIT; 234 npages = atop(size); 235 VM_OBJECT_WLOCK(object); 236 tries = 0; 237 retry: 238 m = vm_page_alloc_contig(object, atop(offset), pflags, 239 npages, low, high, alignment, boundary, memattr); 240 if (m == NULL) { 241 VM_OBJECT_WUNLOCK(object); 242 if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) { 243 if (!vm_page_reclaim_contig(pflags, npages, low, high, 244 alignment, boundary) && (flags & M_WAITOK) != 0) 245 VM_WAIT; 246 VM_OBJECT_WLOCK(object); 247 tries++; 248 goto retry; 249 } 250 vmem_free(vmem, addr, size); 251 return (0); 252 } 253 end_m = m + npages; 254 tmp = addr; 255 for (; m < end_m; m++) { 256 if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0) 257 pmap_zero_page(m); 258 m->valid = VM_PAGE_BITS_ALL; 259 pmap_enter(kernel_pmap, tmp, m, VM_PROT_ALL, 260 VM_PROT_ALL | PMAP_ENTER_WIRED, 0); 261 tmp += PAGE_SIZE; 262 } 263 VM_OBJECT_WUNLOCK(object); 264 return (addr); 265 } 266 267 /* 268 * kmem_suballoc: 269 * 270 * Allocates a map to manage a subrange 271 * of the kernel virtual address space. 272 * 273 * Arguments are as follows: 274 * 275 * parent Map to take range from 276 * min, max Returned endpoints of map 277 * size Size of range to find 278 * superpage_align Request that min is superpage aligned 279 */ 280 vm_map_t 281 kmem_suballoc(vm_map_t parent, vm_offset_t *min, vm_offset_t *max, 282 vm_size_t size, boolean_t superpage_align) 283 { 284 int ret; 285 vm_map_t result; 286 287 size = round_page(size); 288 289 *min = vm_map_min(parent); 290 ret = vm_map_find(parent, NULL, 0, min, size, 0, superpage_align ? 291 VMFS_SUPER_SPACE : VMFS_ANY_SPACE, VM_PROT_ALL, VM_PROT_ALL, 292 MAP_ACC_NO_CHARGE); 293 if (ret != KERN_SUCCESS) 294 panic("kmem_suballoc: bad status return of %d", ret); 295 *max = *min + size; 296 result = vm_map_create(vm_map_pmap(parent), *min, *max); 297 if (result == NULL) 298 panic("kmem_suballoc: cannot create submap"); 299 if (vm_map_submap(parent, *min, *max, result) != KERN_SUCCESS) 300 panic("kmem_suballoc: unable to change range to submap"); 301 return (result); 302 } 303 304 /* 305 * kmem_malloc: 306 * 307 * Allocate wired-down pages in the kernel's address space. 308 */ 309 vm_offset_t 310 kmem_malloc(struct vmem *vmem, vm_size_t size, int flags) 311 { 312 vm_offset_t addr; 313 int rv; 314 315 size = round_page(size); 316 if (vmem_alloc(vmem, size, flags | M_BESTFIT, &addr)) 317 return (0); 318 319 rv = kmem_back((vmem == kmem_arena) ? kmem_object : kernel_object, 320 addr, size, flags); 321 if (rv != KERN_SUCCESS) { 322 vmem_free(vmem, addr, size); 323 return (0); 324 } 325 return (addr); 326 } 327 328 /* 329 * kmem_back: 330 * 331 * Allocate physical pages for the specified virtual address range. 332 */ 333 int 334 kmem_back(vm_object_t object, vm_offset_t addr, vm_size_t size, int flags) 335 { 336 vm_offset_t offset, i; 337 vm_page_t m, mpred; 338 int pflags; 339 340 KASSERT(object == kmem_object || object == kernel_object, 341 ("kmem_back: only supports kernel objects.")); 342 343 offset = addr - VM_MIN_KERNEL_ADDRESS; 344 pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED; 345 pflags &= ~(VM_ALLOC_NOWAIT | VM_ALLOC_WAITOK | VM_ALLOC_WAITFAIL); 346 if (flags & M_WAITOK) 347 pflags |= VM_ALLOC_WAITFAIL; 348 349 i = 0; 350 VM_OBJECT_WLOCK(object); 351 retry: 352 mpred = vm_radix_lookup_le(&object->rtree, atop(offset + i)); 353 for (; i < size; i += PAGE_SIZE, mpred = m) { 354 m = vm_page_alloc_after(object, atop(offset + i), pflags, 355 mpred); 356 357 /* 358 * Ran out of space, free everything up and return. Don't need 359 * to lock page queues here as we know that the pages we got 360 * aren't on any queues. 361 */ 362 if (m == NULL) { 363 if ((flags & M_NOWAIT) == 0) 364 goto retry; 365 VM_OBJECT_WUNLOCK(object); 366 kmem_unback(object, addr, i); 367 return (KERN_NO_SPACE); 368 } 369 if (flags & M_ZERO && (m->flags & PG_ZERO) == 0) 370 pmap_zero_page(m); 371 KASSERT((m->oflags & VPO_UNMANAGED) != 0, 372 ("kmem_malloc: page %p is managed", m)); 373 m->valid = VM_PAGE_BITS_ALL; 374 pmap_enter(kernel_pmap, addr + i, m, VM_PROT_ALL, 375 VM_PROT_ALL | PMAP_ENTER_WIRED, 0); 376 } 377 VM_OBJECT_WUNLOCK(object); 378 379 return (KERN_SUCCESS); 380 } 381 382 /* 383 * kmem_unback: 384 * 385 * Unmap and free the physical pages underlying the specified virtual 386 * address range. 387 * 388 * A physical page must exist within the specified object at each index 389 * that is being unmapped. 390 */ 391 void 392 kmem_unback(vm_object_t object, vm_offset_t addr, vm_size_t size) 393 { 394 vm_page_t m, next; 395 vm_offset_t end, offset; 396 397 KASSERT(object == kmem_object || object == kernel_object, 398 ("kmem_unback: only supports kernel objects.")); 399 400 pmap_remove(kernel_pmap, addr, addr + size); 401 offset = addr - VM_MIN_KERNEL_ADDRESS; 402 end = offset + size; 403 VM_OBJECT_WLOCK(object); 404 for (m = vm_page_lookup(object, atop(offset)); offset < end; 405 offset += PAGE_SIZE, m = next) { 406 next = vm_page_next(m); 407 vm_page_unwire(m, PQ_NONE); 408 vm_page_free(m); 409 } 410 VM_OBJECT_WUNLOCK(object); 411 } 412 413 /* 414 * kmem_free: 415 * 416 * Free memory allocated with kmem_malloc. The size must match the 417 * original allocation. 418 */ 419 void 420 kmem_free(struct vmem *vmem, vm_offset_t addr, vm_size_t size) 421 { 422 423 size = round_page(size); 424 kmem_unback((vmem == kmem_arena) ? kmem_object : kernel_object, 425 addr, size); 426 vmem_free(vmem, addr, size); 427 } 428 429 /* 430 * kmap_alloc_wait: 431 * 432 * Allocates pageable memory from a sub-map of the kernel. If the submap 433 * has no room, the caller sleeps waiting for more memory in the submap. 434 * 435 * This routine may block. 436 */ 437 vm_offset_t 438 kmap_alloc_wait(vm_map_t map, vm_size_t size) 439 { 440 vm_offset_t addr; 441 442 size = round_page(size); 443 if (!swap_reserve(size)) 444 return (0); 445 446 for (;;) { 447 /* 448 * To make this work for more than one map, use the map's lock 449 * to lock out sleepers/wakers. 450 */ 451 vm_map_lock(map); 452 if (vm_map_findspace(map, vm_map_min(map), size, &addr) == 0) 453 break; 454 /* no space now; see if we can ever get space */ 455 if (vm_map_max(map) - vm_map_min(map) < size) { 456 vm_map_unlock(map); 457 swap_release(size); 458 return (0); 459 } 460 map->needs_wakeup = TRUE; 461 vm_map_unlock_and_wait(map, 0); 462 } 463 vm_map_insert(map, NULL, 0, addr, addr + size, VM_PROT_ALL, 464 VM_PROT_ALL, MAP_ACC_CHARGED); 465 vm_map_unlock(map); 466 return (addr); 467 } 468 469 /* 470 * kmap_free_wakeup: 471 * 472 * Returns memory to a submap of the kernel, and wakes up any processes 473 * waiting for memory in that map. 474 */ 475 void 476 kmap_free_wakeup(vm_map_t map, vm_offset_t addr, vm_size_t size) 477 { 478 479 vm_map_lock(map); 480 (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size)); 481 if (map->needs_wakeup) { 482 map->needs_wakeup = FALSE; 483 vm_map_wakeup(map); 484 } 485 vm_map_unlock(map); 486 } 487 488 void 489 kmem_init_zero_region(void) 490 { 491 vm_offset_t addr, i; 492 vm_page_t m; 493 494 /* 495 * Map a single physical page of zeros to a larger virtual range. 496 * This requires less looping in places that want large amounts of 497 * zeros, while not using much more physical resources. 498 */ 499 addr = kva_alloc(ZERO_REGION_SIZE); 500 m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL | 501 VM_ALLOC_NOOBJ | VM_ALLOC_WIRED | VM_ALLOC_ZERO); 502 if ((m->flags & PG_ZERO) == 0) 503 pmap_zero_page(m); 504 for (i = 0; i < ZERO_REGION_SIZE; i += PAGE_SIZE) 505 pmap_qenter(addr + i, &m, 1); 506 pmap_protect(kernel_pmap, addr, addr + ZERO_REGION_SIZE, VM_PROT_READ); 507 508 zero_region = (const void *)addr; 509 } 510 511 /* 512 * kmem_init: 513 * 514 * Create the kernel map; insert a mapping covering kernel text, 515 * data, bss, and all space allocated thus far (`boostrap' data). The 516 * new map will thus map the range between VM_MIN_KERNEL_ADDRESS and 517 * `start' as allocated, and the range between `start' and `end' as free. 518 */ 519 void 520 kmem_init(vm_offset_t start, vm_offset_t end) 521 { 522 vm_map_t m; 523 524 m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end); 525 m->system_map = 1; 526 vm_map_lock(m); 527 /* N.B.: cannot use kgdb to debug, starting with this assignment ... */ 528 kernel_map = m; 529 (void) vm_map_insert(m, NULL, (vm_ooffset_t) 0, 530 #ifdef __amd64__ 531 KERNBASE, 532 #else 533 VM_MIN_KERNEL_ADDRESS, 534 #endif 535 start, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); 536 /* ... and ending with the completion of the above `insert' */ 537 vm_map_unlock(m); 538 } 539 540 #ifdef DIAGNOSTIC 541 /* 542 * Allow userspace to directly trigger the VM drain routine for testing 543 * purposes. 544 */ 545 static int 546 debug_vm_lowmem(SYSCTL_HANDLER_ARGS) 547 { 548 int error, i; 549 550 i = 0; 551 error = sysctl_handle_int(oidp, &i, 0, req); 552 if (error) 553 return (error); 554 if ((i & ~(VM_LOW_KMEM | VM_LOW_PAGES)) != 0) 555 return (EINVAL); 556 if (i != 0) 557 EVENTHANDLER_INVOKE(vm_lowmem, i); 558 return (0); 559 } 560 561 SYSCTL_PROC(_debug, OID_AUTO, vm_lowmem, CTLTYPE_INT | CTLFLAG_RW, 0, 0, 562 debug_vm_lowmem, "I", "set to trigger vm_lowmem event with given flags"); 563 #endif
Cache object: 56f3c6fd4bd0cc5db2242dc312837a90
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