phys_pager.c revision 248084 
1/*-
2 * Copyright (c) 2000 Peter Wemm
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25
26#include <sys/cdefs.h>
27__FBSDID("$FreeBSD: head/sys/vm/phys_pager.c 248084 2013-03-09 02:32:23Z attilio $");
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/conf.h>
32#include <sys/kernel.h>
33#include <sys/lock.h>
34#include <sys/proc.h>
35#include <sys/mutex.h>
36#include <sys/mman.h>
37#include <sys/rwlock.h>
38#include <sys/sysctl.h>
39
40#include <vm/vm.h>
41#include <vm/vm_object.h>
42#include <vm/vm_page.h>
43#include <vm/vm_pager.h>
44
45/* list of phys pager objects */
46static struct pagerlst phys_pager_object_list;
47/* protect access to phys_pager_object_list */
48static struct mtx phys_pager_mtx;
49
50static void
51phys_pager_init(void)
52{
53
54	TAILQ_INIT(&phys_pager_object_list);
55	mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
56}
57
58/*
59 * MPSAFE
60 */
61static vm_object_t
62phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
63    vm_ooffset_t foff, struct ucred *cred)
64{
65	vm_object_t object, object1;
66	vm_pindex_t pindex;
67
68	/*
69	 * Offset should be page aligned.
70	 */
71	if (foff & PAGE_MASK)
72		return (NULL);
73
74	pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
75
76	if (handle != NULL) {
77		mtx_lock(&phys_pager_mtx);
78		/*
79		 * Look up pager, creating as necessary.
80		 */
81		object1 = NULL;
82		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
83		if (object == NULL) {
84			/*
85			 * Allocate object and associate it with the pager.
86			 */
87			mtx_unlock(&phys_pager_mtx);
88			object1 = vm_object_allocate(OBJT_PHYS, pindex);
89			mtx_lock(&phys_pager_mtx);
90			object = vm_pager_object_lookup(&phys_pager_object_list,
91			    handle);
92			if (object != NULL) {
93				/*
94				 * We raced with other thread while
95				 * allocating object.
96				 */
97				if (pindex > object->size)
98					object->size = pindex;
99			} else {
100				object = object1;
101				object1 = NULL;
102				object->handle = handle;
103				TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
104				    pager_object_list);
105			}
106		} else {
107			if (pindex > object->size)
108				object->size = pindex;
109		}
110		mtx_unlock(&phys_pager_mtx);
111		vm_object_deallocate(object1);
112	} else {
113		object = vm_object_allocate(OBJT_PHYS, pindex);
114	}
115
116	return (object);
117}
118
119/*
120 * MPSAFE
121 */
122static void
123phys_pager_dealloc(vm_object_t object)
124{
125
126	if (object->handle != NULL) {
127		VM_OBJECT_WUNLOCK(object);
128		mtx_lock(&phys_pager_mtx);
129		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
130		mtx_unlock(&phys_pager_mtx);
131		VM_OBJECT_WLOCK(object);
132	}
133}
134
135/*
136 * Fill as many pages as vm_fault has allocated for us.
137 */
138static int
139phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
140{
141	int i;
142
143	VM_OBJECT_ASSERT_WLOCKED(object);
144	for (i = 0; i < count; i++) {
145		if (m[i]->valid == 0) {
146			if ((m[i]->flags & PG_ZERO) == 0)
147				pmap_zero_page(m[i]);
148			m[i]->valid = VM_PAGE_BITS_ALL;
149		}
150		KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
151		    ("phys_pager_getpages: partially valid page %p", m[i]));
152		KASSERT(m[i]->dirty == 0,
153		    ("phys_pager_getpages: dirty page %p", m[i]));
154		/* The requested page must remain busy, the others not. */
155		if (i == reqpage)
156			vm_page_flash(m[i]);
157		else
158			vm_page_wakeup(m[i]);
159	}
160	return (VM_PAGER_OK);
161}
162
163static void
164phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
165		    int *rtvals)
166{
167
168	panic("phys_pager_putpage called");
169}
170
171/*
172 * Implement a pretty aggressive clustered getpages strategy.  Hint that
173 * everything in an entire 4MB window should be prefaulted at once.
174 *
175 * XXX 4MB (1024 slots per page table page) is convenient for x86,
176 * but may not be for other arches.
177 */
178#ifndef PHYSCLUSTER
179#define PHYSCLUSTER 1024
180#endif
181static boolean_t
182phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
183		   int *after)
184{
185	vm_pindex_t base, end;
186
187	base = pindex & (~(PHYSCLUSTER - 1));
188	end = base + (PHYSCLUSTER - 1);
189	if (before != NULL)
190		*before = pindex - base;
191	if (after != NULL)
192		*after = end - pindex;
193	return (TRUE);
194}
195
196struct pagerops physpagerops = {
197	.pgo_init =	phys_pager_init,
198	.pgo_alloc =	phys_pager_alloc,
199	.pgo_dealloc = 	phys_pager_dealloc,
200	.pgo_getpages =	phys_pager_getpages,
201	.pgo_putpages =	phys_pager_putpages,
202	.pgo_haspage =	phys_pager_haspage,
203};
204