FreeBSD/Linux Kernel Cross Reference
sys/vm/vm_kern.c
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/10.0/sys/vm/vm_kern.c 255426 2013-09-09 18:11:59Z jhb $");
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_extern.h>
88 #include <vm/uma.h>
89
90 vm_map_t kernel_map;
91 vm_map_t exec_map;
92 vm_map_t pipe_map;
93
94 const void *zero_region;
95 CTASSERT((ZERO_REGION_SIZE & PAGE_MASK) == 0);
96
97 SYSCTL_ULONG(_vm, OID_AUTO, min_kernel_address, CTLFLAG_RD,
98 NULL, VM_MIN_KERNEL_ADDRESS, "Min kernel address");
99
100 SYSCTL_ULONG(_vm, OID_AUTO, max_kernel_address, CTLFLAG_RD,
101 #if defined(__arm__) || defined(__sparc64__)
102 &vm_max_kernel_address, 0,
103 #else
104 NULL, VM_MAX_KERNEL_ADDRESS,
105 #endif
106 "Max kernel address");
107
108 /*
109 * kva_alloc:
110 *
111 * Allocate a virtual address range with no underlying object and
112 * no initial mapping to physical memory. Any mapping from this
113 * range to physical memory must be explicitly created prior to
114 * its use, typically with pmap_qenter(). Any attempt to create
115 * a mapping on demand through vm_fault() will result in a panic.
116 */
117 vm_offset_t
118 kva_alloc(size)
119 vm_size_t size;
120 {
121 vm_offset_t addr;
122
123 size = round_page(size);
124 if (vmem_alloc(kernel_arena, size, M_BESTFIT | M_NOWAIT, &addr))
125 return (0);
126
127 return (addr);
128 }
129
130 /*
131 * kva_free:
132 *
133 * Release a region of kernel virtual memory allocated
134 * with kva_alloc, and return the physical pages
135 * associated with that region.
136 *
137 * This routine may not block on kernel maps.
138 */
139 void
140 kva_free(addr, size)
141 vm_offset_t addr;
142 vm_size_t size;
143 {
144
145 size = round_page(size);
146 vmem_free(kernel_arena, addr, size);
147 }
148
149 /*
150 * Allocates a region from the kernel address map and physical pages
151 * within the specified address range to the kernel object. Creates a
152 * wired mapping from this region to these pages, and returns the
153 * region's starting virtual address. The allocated pages are not
154 * necessarily physically contiguous. If M_ZERO is specified through the
155 * given flags, then the pages are zeroed before they are mapped.
156 */
157 vm_offset_t
158 kmem_alloc_attr(vmem_t *vmem, vm_size_t size, int flags, vm_paddr_t low,
159 vm_paddr_t high, vm_memattr_t memattr)
160 {
161 vm_object_t object = vmem == kmem_arena ? kmem_object : kernel_object;
162 vm_offset_t addr;
163 vm_ooffset_t offset;
164 vm_page_t m;
165 int pflags, tries;
166 int i;
167
168 size = round_page(size);
169 if (vmem_alloc(vmem, size, M_BESTFIT | flags, &addr))
170 return (0);
171 offset = addr - VM_MIN_KERNEL_ADDRESS;
172 pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED;
173 VM_OBJECT_WLOCK(object);
174 for (i = 0; i < size; i += PAGE_SIZE) {
175 tries = 0;
176 retry:
177 m = vm_page_alloc_contig(object, OFF_TO_IDX(offset + i),
178 pflags, 1, low, high, PAGE_SIZE, 0, memattr);
179 if (m == NULL) {
180 VM_OBJECT_WUNLOCK(object);
181 if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
182 vm_pageout_grow_cache(tries, low, high);
183 VM_OBJECT_WLOCK(object);
184 tries++;
185 goto retry;
186 }
187 /*
188 * Unmap and free the pages.
189 */
190 if (i != 0)
191 pmap_remove(kernel_pmap, addr, addr + i);
192 while (i != 0) {
193 i -= PAGE_SIZE;
194 m = vm_page_lookup(object,
195 OFF_TO_IDX(offset + i));
196 vm_page_unwire(m, 0);
197 vm_page_free(m);
198 }
199 vmem_free(vmem, addr, size);
200 return (0);
201 }
202 if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0)
203 pmap_zero_page(m);
204 m->valid = VM_PAGE_BITS_ALL;
205 pmap_enter(kernel_pmap, addr + i, VM_PROT_ALL, m, VM_PROT_ALL,
206 TRUE);
207 }
208 VM_OBJECT_WUNLOCK(object);
209 return (addr);
210 }
211
212 /*
213 * Allocates a region from the kernel address map and physically
214 * contiguous pages within the specified address range to the kernel
215 * object. Creates a wired mapping from this region to these pages, and
216 * returns the region's starting virtual address. If M_ZERO is specified
217 * through the given flags, then the pages are zeroed before they are
218 * mapped.
219 */
220 vm_offset_t
221 kmem_alloc_contig(struct vmem *vmem, vm_size_t size, int flags, vm_paddr_t low,
222 vm_paddr_t high, u_long alignment, vm_paddr_t boundary,
223 vm_memattr_t memattr)
224 {
225 vm_object_t object = vmem == kmem_arena ? kmem_object : kernel_object;
226 vm_offset_t addr, tmp;
227 vm_ooffset_t offset;
228 vm_page_t end_m, m;
229 int pflags, tries;
230
231 size = round_page(size);
232 if (vmem_alloc(vmem, size, flags | M_BESTFIT, &addr))
233 return (0);
234 offset = addr - VM_MIN_KERNEL_ADDRESS;
235 pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED;
236 VM_OBJECT_WLOCK(object);
237 tries = 0;
238 retry:
239 m = vm_page_alloc_contig(object, OFF_TO_IDX(offset), pflags,
240 atop(size), low, high, alignment, boundary, memattr);
241 if (m == NULL) {
242 VM_OBJECT_WUNLOCK(object);
243 if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
244 vm_pageout_grow_cache(tries, low, high);
245 VM_OBJECT_WLOCK(object);
246 tries++;
247 goto retry;
248 }
249 vmem_free(vmem, addr, size);
250 return (0);
251 }
252 end_m = m + atop(size);
253 tmp = addr;
254 for (; m < end_m; m++) {
255 if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0)
256 pmap_zero_page(m);
257 m->valid = VM_PAGE_BITS_ALL;
258 pmap_enter(kernel_pmap, tmp, VM_PROT_ALL, m, VM_PROT_ALL, true);
259 tmp += PAGE_SIZE;
260 }
261 VM_OBJECT_WUNLOCK(object);
262 return (addr);
263 }
264
265 /*
266 * kmem_suballoc:
267 *
268 * Allocates a map to manage a subrange
269 * of the kernel virtual address space.
270 *
271 * Arguments are as follows:
272 *
273 * parent Map to take range from
274 * min, max Returned endpoints of map
275 * size Size of range to find
276 * superpage_align Request that min is superpage aligned
277 */
278 vm_map_t
279 kmem_suballoc(vm_map_t parent, vm_offset_t *min, vm_offset_t *max,
280 vm_size_t size, boolean_t superpage_align)
281 {
282 int ret;
283 vm_map_t result;
284
285 size = round_page(size);
286
287 *min = vm_map_min(parent);
288 ret = vm_map_find(parent, NULL, 0, min, size, 0, superpage_align ?
289 VMFS_SUPER_SPACE : VMFS_ANY_SPACE, VM_PROT_ALL, VM_PROT_ALL,
290 MAP_ACC_NO_CHARGE);
291 if (ret != KERN_SUCCESS)
292 panic("kmem_suballoc: bad status return of %d", ret);
293 *max = *min + size;
294 result = vm_map_create(vm_map_pmap(parent), *min, *max);
295 if (result == NULL)
296 panic("kmem_suballoc: cannot create submap");
297 if (vm_map_submap(parent, *min, *max, result) != KERN_SUCCESS)
298 panic("kmem_suballoc: unable to change range to submap");
299 return (result);
300 }
301
302 /*
303 * kmem_malloc:
304 *
305 * Allocate wired-down pages in the kernel's address space.
306 */
307 vm_offset_t
308 kmem_malloc(struct vmem *vmem, vm_size_t size, int flags)
309 {
310 vm_offset_t addr;
311 int rv;
312
313 size = round_page(size);
314 if (vmem_alloc(vmem, size, flags | M_BESTFIT, &addr))
315 return (0);
316
317 rv = kmem_back((vmem == kmem_arena) ? kmem_object : kernel_object,
318 addr, size, flags);
319 if (rv != KERN_SUCCESS) {
320 vmem_free(vmem, addr, size);
321 return (0);
322 }
323 return (addr);
324 }
325
326 /*
327 * kmem_back:
328 *
329 * Allocate physical pages for the specified virtual address range.
330 */
331 int
332 kmem_back(vm_object_t object, vm_offset_t addr, vm_size_t size, int flags)
333 {
334 vm_offset_t offset, i;
335 vm_page_t m;
336 int pflags;
337
338 KASSERT(object == kmem_object || object == kernel_object,
339 ("kmem_back: only supports kernel objects."));
340
341 offset = addr - VM_MIN_KERNEL_ADDRESS;
342 pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED;
343
344 VM_OBJECT_WLOCK(object);
345 for (i = 0; i < size; i += PAGE_SIZE) {
346 retry:
347 m = vm_page_alloc(object, OFF_TO_IDX(offset + i), pflags);
348
349 /*
350 * Ran out of space, free everything up and return. Don't need
351 * to lock page queues here as we know that the pages we got
352 * aren't on any queues.
353 */
354 if (m == NULL) {
355 if ((flags & M_NOWAIT) == 0) {
356 VM_OBJECT_WUNLOCK(object);
357 VM_WAIT;
358 VM_OBJECT_WLOCK(object);
359 goto retry;
360 }
361 /*
362 * Unmap and free the pages.
363 */
364 if (i != 0)
365 pmap_remove(kernel_pmap, addr, addr + i);
366 while (i != 0) {
367 i -= PAGE_SIZE;
368 m = vm_page_lookup(object,
369 OFF_TO_IDX(offset + i));
370 vm_page_unwire(m, 0);
371 vm_page_free(m);
372 }
373 VM_OBJECT_WUNLOCK(object);
374 return (KERN_NO_SPACE);
375 }
376 if (flags & M_ZERO && (m->flags & PG_ZERO) == 0)
377 pmap_zero_page(m);
378 KASSERT((m->oflags & VPO_UNMANAGED) != 0,
379 ("kmem_malloc: page %p is managed", m));
380 m->valid = VM_PAGE_BITS_ALL;
381 pmap_enter(kernel_pmap, addr + i, VM_PROT_ALL, m, VM_PROT_ALL,
382 TRUE);
383 }
384 VM_OBJECT_WUNLOCK(object);
385
386 return (KERN_SUCCESS);
387 }
388
389 void
390 kmem_unback(vm_object_t object, vm_offset_t addr, vm_size_t size)
391 {
392 vm_page_t m;
393 vm_offset_t offset;
394 int i;
395
396 KASSERT(object == kmem_object || object == kernel_object,
397 ("kmem_unback: only supports kernel objects."));
398
399 offset = addr - VM_MIN_KERNEL_ADDRESS;
400 VM_OBJECT_WLOCK(object);
401 pmap_remove(kernel_pmap, addr, addr + size);
402 for (i = 0; i < size; i += PAGE_SIZE) {
403 m = vm_page_lookup(object, OFF_TO_IDX(offset + i));
404 vm_page_unwire(m, 0);
405 vm_page_free(m);
406 }
407 VM_OBJECT_WUNLOCK(object);
408 }
409
410 /*
411 * kmem_free:
412 *
413 * Free memory allocated with kmem_malloc. The size must match the
414 * original allocation.
415 */
416 void
417 kmem_free(struct vmem *vmem, vm_offset_t addr, vm_size_t size)
418 {
419
420 size = round_page(size);
421 kmem_unback((vmem == kmem_arena) ? kmem_object : kernel_object,
422 addr, size);
423 vmem_free(vmem, addr, size);
424 }
425
426 /*
427 * kmap_alloc_wait:
428 *
429 * Allocates pageable memory from a sub-map of the kernel. If the submap
430 * has no room, the caller sleeps waiting for more memory in the submap.
431 *
432 * This routine may block.
433 */
434 vm_offset_t
435 kmap_alloc_wait(map, size)
436 vm_map_t map;
437 vm_size_t size;
438 {
439 vm_offset_t addr;
440
441 size = round_page(size);
442 if (!swap_reserve(size))
443 return (0);
444
445 for (;;) {
446 /*
447 * To make this work for more than one map, use the map's lock
448 * to lock out sleepers/wakers.
449 */
450 vm_map_lock(map);
451 if (vm_map_findspace(map, vm_map_min(map), size, &addr) == 0)
452 break;
453 /* no space now; see if we can ever get space */
454 if (vm_map_max(map) - vm_map_min(map) < size) {
455 vm_map_unlock(map);
456 swap_release(size);
457 return (0);
458 }
459 map->needs_wakeup = TRUE;
460 vm_map_unlock_and_wait(map, 0);
461 }
462 vm_map_insert(map, NULL, 0, addr, addr + size, VM_PROT_ALL,
463 VM_PROT_ALL, MAP_ACC_CHARGED);
464 vm_map_unlock(map);
465 return (addr);
466 }
467
468 /*
469 * kmap_free_wakeup:
470 *
471 * Returns memory to a submap of the kernel, and wakes up any processes
472 * waiting for memory in that map.
473 */
474 void
475 kmap_free_wakeup(map, addr, size)
476 vm_map_t map;
477 vm_offset_t addr;
478 vm_size_t size;
479 {
480
481 vm_map_lock(map);
482 (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size));
483 if (map->needs_wakeup) {
484 map->needs_wakeup = FALSE;
485 vm_map_wakeup(map);
486 }
487 vm_map_unlock(map);
488 }
489
490 void
491 kmem_init_zero_region(void)
492 {
493 vm_offset_t addr, i;
494 vm_page_t m;
495
496 /*
497 * Map a single physical page of zeros to a larger virtual range.
498 * This requires less looping in places that want large amounts of
499 * zeros, while not using much more physical resources.
500 */
501 addr = kva_alloc(ZERO_REGION_SIZE);
502 m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
503 VM_ALLOC_NOOBJ | VM_ALLOC_WIRED | VM_ALLOC_ZERO);
504 if ((m->flags & PG_ZERO) == 0)
505 pmap_zero_page(m);
506 for (i = 0; i < ZERO_REGION_SIZE; i += PAGE_SIZE)
507 pmap_qenter(addr + i, &m, 1);
508 pmap_protect(kernel_pmap, addr, addr + ZERO_REGION_SIZE, VM_PROT_READ);
509
510 zero_region = (const void *)addr;
511 }
512
513 /*
514 * kmem_init:
515 *
516 * Create the kernel map; insert a mapping covering kernel text,
517 * data, bss, and all space allocated thus far (`boostrap' data). The
518 * new map will thus map the range between VM_MIN_KERNEL_ADDRESS and
519 * `start' as allocated, and the range between `start' and `end' as free.
520 */
521 void
522 kmem_init(start, end)
523 vm_offset_t start, end;
524 {
525 vm_map_t m;
526
527 m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end);
528 m->system_map = 1;
529 vm_map_lock(m);
530 /* N.B.: cannot use kgdb to debug, starting with this assignment ... */
531 kernel_map = m;
532 (void) vm_map_insert(m, NULL, (vm_ooffset_t) 0,
533 #ifdef __amd64__
534 KERNBASE,
535 #else
536 VM_MIN_KERNEL_ADDRESS,
537 #endif
538 start, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
539 /* ... and ending with the completion of the above `insert' */
540 vm_map_unlock(m);
541 }
542
543 #ifdef DIAGNOSTIC
544 /*
545 * Allow userspace to directly trigger the VM drain routine for testing
546 * purposes.
547 */
548 static int
549 debug_vm_lowmem(SYSCTL_HANDLER_ARGS)
550 {
551 int error, i;
552
553 i = 0;
554 error = sysctl_handle_int(oidp, &i, 0, req);
555 if (error)
556 return (error);
557 if (i)
558 EVENTHANDLER_INVOKE(vm_lowmem, 0);
559 return (0);
560 }
561
562 SYSCTL_PROC(_debug, OID_AUTO, vm_lowmem, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
563 debug_vm_lowmem, "I", "set to trigger vm_lowmem event");
564 #endif
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