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/11.0/sys/vm/vm_kern.c 292469 2015-12-19 18:42:50Z alc $");
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 /* NB: Used by kernel debuggers. */
98 const u_long vm_maxuser_address = VM_MAXUSER_ADDRESS;
99
100 SYSCTL_ULONG(_vm, OID_AUTO, min_kernel_address, CTLFLAG_RD,
101 SYSCTL_NULL_ULONG_PTR, VM_MIN_KERNEL_ADDRESS, "Min kernel address");
102
103 SYSCTL_ULONG(_vm, OID_AUTO, max_kernel_address, CTLFLAG_RD,
104 #if defined(__arm__) || defined(__sparc64__)
105 &vm_max_kernel_address, 0,
106 #else
107 SYSCTL_NULL_ULONG_PTR, VM_MAX_KERNEL_ADDRESS,
108 #endif
109 "Max kernel address");
110
111 /*
112 * kva_alloc:
113 *
114 * Allocate a virtual address range with no underlying object and
115 * no initial mapping to physical memory. Any mapping from this
116 * range to physical memory must be explicitly created prior to
117 * its use, typically with pmap_qenter(). Any attempt to create
118 * a mapping on demand through vm_fault() will result in a panic.
119 */
120 vm_offset_t
121 kva_alloc(size)
122 vm_size_t size;
123 {
124 vm_offset_t addr;
125
126 size = round_page(size);
127 if (vmem_alloc(kernel_arena, size, M_BESTFIT | M_NOWAIT, &addr))
128 return (0);
129
130 return (addr);
131 }
132
133 /*
134 * kva_free:
135 *
136 * Release a region of kernel virtual memory allocated
137 * with kva_alloc, and return the physical pages
138 * associated with that region.
139 *
140 * This routine may not block on kernel maps.
141 */
142 void
143 kva_free(addr, size)
144 vm_offset_t addr;
145 vm_size_t size;
146 {
147
148 size = round_page(size);
149 vmem_free(kernel_arena, addr, size);
150 }
151
152 /*
153 * Allocates a region from the kernel address map and physical pages
154 * within the specified address range to the kernel object. Creates a
155 * wired mapping from this region to these pages, and returns the
156 * region's starting virtual address. The allocated pages are not
157 * necessarily physically contiguous. If M_ZERO is specified through the
158 * given flags, then the pages are zeroed before they are mapped.
159 */
160 vm_offset_t
161 kmem_alloc_attr(vmem_t *vmem, vm_size_t size, int flags, vm_paddr_t low,
162 vm_paddr_t high, vm_memattr_t memattr)
163 {
164 vm_object_t object = vmem == kmem_arena ? kmem_object : kernel_object;
165 vm_offset_t addr, i;
166 vm_ooffset_t 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 VM_OBJECT_WLOCK(object);
176 for (i = 0; i < size; i += PAGE_SIZE) {
177 tries = 0;
178 retry:
179 m = vm_page_alloc_contig(object, OFF_TO_IDX(offset + i),
180 pflags, 1, low, high, PAGE_SIZE, 0, memattr);
181 if (m == NULL) {
182 VM_OBJECT_WUNLOCK(object);
183 if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
184 if (!vm_page_reclaim_contig(pflags, 1,
185 low, high, PAGE_SIZE, 0) &&
186 (flags & M_WAITOK) != 0)
187 VM_WAIT;
188 VM_OBJECT_WLOCK(object);
189 tries++;
190 goto retry;
191 }
192 kmem_unback(object, addr, i);
193 vmem_free(vmem, addr, size);
194 return (0);
195 }
196 if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0)
197 pmap_zero_page(m);
198 m->valid = VM_PAGE_BITS_ALL;
199 pmap_enter(kernel_pmap, addr + i, m, VM_PROT_ALL,
200 VM_PROT_ALL | PMAP_ENTER_WIRED, 0);
201 }
202 VM_OBJECT_WUNLOCK(object);
203 return (addr);
204 }
205
206 /*
207 * Allocates a region from the kernel address map and physically
208 * contiguous pages within the specified address range to the kernel
209 * object. Creates a wired mapping from this region to these pages, and
210 * returns the region's starting virtual address. If M_ZERO is specified
211 * through the given flags, then the pages are zeroed before they are
212 * mapped.
213 */
214 vm_offset_t
215 kmem_alloc_contig(struct vmem *vmem, vm_size_t size, int flags, vm_paddr_t low,
216 vm_paddr_t high, u_long alignment, vm_paddr_t boundary,
217 vm_memattr_t memattr)
218 {
219 vm_object_t object = vmem == kmem_arena ? kmem_object : kernel_object;
220 vm_offset_t addr, tmp;
221 vm_ooffset_t offset;
222 vm_page_t end_m, m;
223 u_long npages;
224 int pflags, tries;
225
226 size = round_page(size);
227 if (vmem_alloc(vmem, size, flags | M_BESTFIT, &addr))
228 return (0);
229 offset = addr - VM_MIN_KERNEL_ADDRESS;
230 pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED;
231 npages = atop(size);
232 VM_OBJECT_WLOCK(object);
233 tries = 0;
234 retry:
235 m = vm_page_alloc_contig(object, OFF_TO_IDX(offset), pflags,
236 npages, low, high, alignment, boundary, memattr);
237 if (m == NULL) {
238 VM_OBJECT_WUNLOCK(object);
239 if (tries < ((flags & M_NOWAIT) != 0 ? 1 : 3)) {
240 if (!vm_page_reclaim_contig(pflags, npages, low, high,
241 alignment, boundary) && (flags & M_WAITOK) != 0)
242 VM_WAIT;
243 VM_OBJECT_WLOCK(object);
244 tries++;
245 goto retry;
246 }
247 vmem_free(vmem, addr, size);
248 return (0);
249 }
250 end_m = m + npages;
251 tmp = addr;
252 for (; m < end_m; m++) {
253 if ((flags & M_ZERO) && (m->flags & PG_ZERO) == 0)
254 pmap_zero_page(m);
255 m->valid = VM_PAGE_BITS_ALL;
256 pmap_enter(kernel_pmap, tmp, m, VM_PROT_ALL,
257 VM_PROT_ALL | PMAP_ENTER_WIRED, 0);
258 tmp += PAGE_SIZE;
259 }
260 VM_OBJECT_WUNLOCK(object);
261 return (addr);
262 }
263
264 /*
265 * kmem_suballoc:
266 *
267 * Allocates a map to manage a subrange
268 * of the kernel virtual address space.
269 *
270 * Arguments are as follows:
271 *
272 * parent Map to take range from
273 * min, max Returned endpoints of map
274 * size Size of range to find
275 * superpage_align Request that min is superpage aligned
276 */
277 vm_map_t
278 kmem_suballoc(vm_map_t parent, vm_offset_t *min, vm_offset_t *max,
279 vm_size_t size, boolean_t superpage_align)
280 {
281 int ret;
282 vm_map_t result;
283
284 size = round_page(size);
285
286 *min = vm_map_min(parent);
287 ret = vm_map_find(parent, NULL, 0, min, size, 0, superpage_align ?
288 VMFS_SUPER_SPACE : VMFS_ANY_SPACE, VM_PROT_ALL, VM_PROT_ALL,
289 MAP_ACC_NO_CHARGE);
290 if (ret != KERN_SUCCESS)
291 panic("kmem_suballoc: bad status return of %d", ret);
292 *max = *min + size;
293 result = vm_map_create(vm_map_pmap(parent), *min, *max);
294 if (result == NULL)
295 panic("kmem_suballoc: cannot create submap");
296 if (vm_map_submap(parent, *min, *max, result) != KERN_SUCCESS)
297 panic("kmem_suballoc: unable to change range to submap");
298 return (result);
299 }
300
301 /*
302 * kmem_malloc:
303 *
304 * Allocate wired-down pages in the kernel's address space.
305 */
306 vm_offset_t
307 kmem_malloc(struct vmem *vmem, vm_size_t size, int flags)
308 {
309 vm_offset_t addr;
310 int rv;
311
312 size = round_page(size);
313 if (vmem_alloc(vmem, size, flags | M_BESTFIT, &addr))
314 return (0);
315
316 rv = kmem_back((vmem == kmem_arena) ? kmem_object : kernel_object,
317 addr, size, flags);
318 if (rv != KERN_SUCCESS) {
319 vmem_free(vmem, addr, size);
320 return (0);
321 }
322 return (addr);
323 }
324
325 /*
326 * kmem_back:
327 *
328 * Allocate physical pages for the specified virtual address range.
329 */
330 int
331 kmem_back(vm_object_t object, vm_offset_t addr, vm_size_t size, int flags)
332 {
333 vm_offset_t offset, i;
334 vm_page_t m;
335 int pflags;
336
337 KASSERT(object == kmem_object || object == kernel_object,
338 ("kmem_back: only supports kernel objects."));
339
340 offset = addr - VM_MIN_KERNEL_ADDRESS;
341 pflags = malloc2vm_flags(flags) | VM_ALLOC_NOBUSY | VM_ALLOC_WIRED;
342
343 VM_OBJECT_WLOCK(object);
344 for (i = 0; i < size; i += PAGE_SIZE) {
345 retry:
346 m = vm_page_alloc(object, OFF_TO_IDX(offset + i), pflags);
347
348 /*
349 * Ran out of space, free everything up and return. Don't need
350 * to lock page queues here as we know that the pages we got
351 * aren't on any queues.
352 */
353 if (m == NULL) {
354 VM_OBJECT_WUNLOCK(object);
355 if ((flags & M_NOWAIT) == 0) {
356 VM_WAIT;
357 VM_OBJECT_WLOCK(object);
358 goto retry;
359 }
360 kmem_unback(object, addr, i);
361 return (KERN_NO_SPACE);
362 }
363 if (flags & M_ZERO && (m->flags & PG_ZERO) == 0)
364 pmap_zero_page(m);
365 KASSERT((m->oflags & VPO_UNMANAGED) != 0,
366 ("kmem_malloc: page %p is managed", m));
367 m->valid = VM_PAGE_BITS_ALL;
368 pmap_enter(kernel_pmap, addr + i, m, VM_PROT_ALL,
369 VM_PROT_ALL | PMAP_ENTER_WIRED, 0);
370 }
371 VM_OBJECT_WUNLOCK(object);
372
373 return (KERN_SUCCESS);
374 }
375
376 /*
377 * kmem_unback:
378 *
379 * Unmap and free the physical pages underlying the specified virtual
380 * address range.
381 *
382 * A physical page must exist within the specified object at each index
383 * that is being unmapped.
384 */
385 void
386 kmem_unback(vm_object_t object, vm_offset_t addr, vm_size_t size)
387 {
388 vm_page_t m;
389 vm_offset_t i, offset;
390
391 KASSERT(object == kmem_object || object == kernel_object,
392 ("kmem_unback: only supports kernel objects."));
393
394 pmap_remove(kernel_pmap, addr, addr + size);
395 offset = addr - VM_MIN_KERNEL_ADDRESS;
396 VM_OBJECT_WLOCK(object);
397 for (i = 0; i < size; i += PAGE_SIZE) {
398 m = vm_page_lookup(object, OFF_TO_IDX(offset + i));
399 vm_page_unwire(m, PQ_NONE);
400 vm_page_free(m);
401 }
402 VM_OBJECT_WUNLOCK(object);
403 }
404
405 /*
406 * kmem_free:
407 *
408 * Free memory allocated with kmem_malloc. The size must match the
409 * original allocation.
410 */
411 void
412 kmem_free(struct vmem *vmem, vm_offset_t addr, vm_size_t size)
413 {
414
415 size = round_page(size);
416 kmem_unback((vmem == kmem_arena) ? kmem_object : kernel_object,
417 addr, size);
418 vmem_free(vmem, addr, size);
419 }
420
421 /*
422 * kmap_alloc_wait:
423 *
424 * Allocates pageable memory from a sub-map of the kernel. If the submap
425 * has no room, the caller sleeps waiting for more memory in the submap.
426 *
427 * This routine may block.
428 */
429 vm_offset_t
430 kmap_alloc_wait(map, size)
431 vm_map_t map;
432 vm_size_t size;
433 {
434 vm_offset_t addr;
435
436 size = round_page(size);
437 if (!swap_reserve(size))
438 return (0);
439
440 for (;;) {
441 /*
442 * To make this work for more than one map, use the map's lock
443 * to lock out sleepers/wakers.
444 */
445 vm_map_lock(map);
446 if (vm_map_findspace(map, vm_map_min(map), size, &addr) == 0)
447 break;
448 /* no space now; see if we can ever get space */
449 if (vm_map_max(map) - vm_map_min(map) < size) {
450 vm_map_unlock(map);
451 swap_release(size);
452 return (0);
453 }
454 map->needs_wakeup = TRUE;
455 vm_map_unlock_and_wait(map, 0);
456 }
457 vm_map_insert(map, NULL, 0, addr, addr + size, VM_PROT_ALL,
458 VM_PROT_ALL, MAP_ACC_CHARGED);
459 vm_map_unlock(map);
460 return (addr);
461 }
462
463 /*
464 * kmap_free_wakeup:
465 *
466 * Returns memory to a submap of the kernel, and wakes up any processes
467 * waiting for memory in that map.
468 */
469 void
470 kmap_free_wakeup(map, addr, size)
471 vm_map_t map;
472 vm_offset_t addr;
473 vm_size_t size;
474 {
475
476 vm_map_lock(map);
477 (void) vm_map_delete(map, trunc_page(addr), round_page(addr + size));
478 if (map->needs_wakeup) {
479 map->needs_wakeup = FALSE;
480 vm_map_wakeup(map);
481 }
482 vm_map_unlock(map);
483 }
484
485 void
486 kmem_init_zero_region(void)
487 {
488 vm_offset_t addr, i;
489 vm_page_t m;
490
491 /*
492 * Map a single physical page of zeros to a larger virtual range.
493 * This requires less looping in places that want large amounts of
494 * zeros, while not using much more physical resources.
495 */
496 addr = kva_alloc(ZERO_REGION_SIZE);
497 m = vm_page_alloc(NULL, 0, VM_ALLOC_NORMAL |
498 VM_ALLOC_NOOBJ | VM_ALLOC_WIRED | VM_ALLOC_ZERO);
499 if ((m->flags & PG_ZERO) == 0)
500 pmap_zero_page(m);
501 for (i = 0; i < ZERO_REGION_SIZE; i += PAGE_SIZE)
502 pmap_qenter(addr + i, &m, 1);
503 pmap_protect(kernel_pmap, addr, addr + ZERO_REGION_SIZE, VM_PROT_READ);
504
505 zero_region = (const void *)addr;
506 }
507
508 /*
509 * kmem_init:
510 *
511 * Create the kernel map; insert a mapping covering kernel text,
512 * data, bss, and all space allocated thus far (`boostrap' data). The
513 * new map will thus map the range between VM_MIN_KERNEL_ADDRESS and
514 * `start' as allocated, and the range between `start' and `end' as free.
515 */
516 void
517 kmem_init(start, end)
518 vm_offset_t start, end;
519 {
520 vm_map_t m;
521
522 m = vm_map_create(kernel_pmap, VM_MIN_KERNEL_ADDRESS, end);
523 m->system_map = 1;
524 vm_map_lock(m);
525 /* N.B.: cannot use kgdb to debug, starting with this assignment ... */
526 kernel_map = m;
527 (void) vm_map_insert(m, NULL, (vm_ooffset_t) 0,
528 #ifdef __amd64__
529 KERNBASE,
530 #else
531 VM_MIN_KERNEL_ADDRESS,
532 #endif
533 start, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT);
534 /* ... and ending with the completion of the above `insert' */
535 vm_map_unlock(m);
536 }
537
538 #ifdef DIAGNOSTIC
539 /*
540 * Allow userspace to directly trigger the VM drain routine for testing
541 * purposes.
542 */
543 static int
544 debug_vm_lowmem(SYSCTL_HANDLER_ARGS)
545 {
546 int error, i;
547
548 i = 0;
549 error = sysctl_handle_int(oidp, &i, 0, req);
550 if (error)
551 return (error);
552 if (i)
553 EVENTHANDLER_INVOKE(vm_lowmem, 0);
554 return (0);
555 }
556
557 SYSCTL_PROC(_debug, OID_AUTO, vm_lowmem, CTLTYPE_INT | CTLFLAG_RW, 0, 0,
558 debug_vm_lowmem, "I", "set to trigger vm_lowmem event");
559 #endif
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