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

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58 * rights to redistribute these changes.
59 */
60
61/*
62 * Kernel memory management.
63 */
64
65#include <sys/cdefs.h>
66__FBSDID("$FreeBSD: head/sys/vm/vm_kern.c 254025 2013-08-07 06:21:20Z jeff $");
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
90vm_map_t kernel_map;
91vm_map_t exec_map;
92vm_map_t pipe_map;
93
94const void *zero_region;
95CTASSERT((ZERO_REGION_SIZE & PAGE_MASK) == 0);
96
97SYSCTL_ULONG(_vm, OID_AUTO, min_kernel_address, CTLFLAG_RD,
98 NULL, VM_MIN_KERNEL_ADDRESS, "Min kernel address");
99
100SYSCTL_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 */
117vm_offset_t
118kva_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 */
139void
140kva_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 */
157vm_offset_t
158kmem_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;
176retry:
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 */
220vm_offset_t
221kmem_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;
238retry:
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

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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 */
307vm_offset_t
308kmem_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 */
331int
332kmem_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) {
346retry:
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
389void
390kmem_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 */
416void
417kmem_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 */
434vm_offset_t
435kmap_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);

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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 */
474void
475kmap_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
490void
491kmem_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,

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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 */
548static int

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