phys_pager.c revision 171737 
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 171737 2007-08-05 21:04:32Z alc $");
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/linker_set.h>
32#include <sys/conf.h>
33#include <sys/kernel.h>
34#include <sys/lock.h>
35#include <sys/proc.h>
36#include <sys/mutex.h>
37#include <sys/mman.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/* prevent concurrent creation races */
46static int phys_pager_alloc_lock;
47/* list of device pager objects */
48static struct pagerlst phys_pager_object_list;
49/* protect access to phys_pager_object_list */
50static struct mtx phys_pager_mtx;
51
52static void
53phys_pager_init(void)
54{
55
56	TAILQ_INIT(&phys_pager_object_list);
57	mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
58}
59
60/*
61 * MPSAFE
62 */
63static vm_object_t
64phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
65		 vm_ooffset_t foff)
66{
67	vm_object_t object;
68	vm_pindex_t pindex;
69
70	/*
71	 * Offset should be page aligned.
72	 */
73	if (foff & PAGE_MASK)
74		return (NULL);
75
76	pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
77
78	if (handle != NULL) {
79		mtx_lock(&Giant);
80		/*
81		 * Lock to prevent object creation race condition.
82		 */
83		while (phys_pager_alloc_lock) {
84			phys_pager_alloc_lock = -1;
85			tsleep(&phys_pager_alloc_lock, PVM, "swpalc", 0);
86		}
87		phys_pager_alloc_lock = 1;
88
89		/*
90		 * Look up pager, creating as necessary.
91		 */
92		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
93		if (object == NULL) {
94			/*
95			 * Allocate object and associate it with the pager.
96			 */
97			object = vm_object_allocate(OBJT_PHYS, pindex);
98			object->handle = handle;
99			mtx_lock(&phys_pager_mtx);
100			TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
101			    pager_object_list);
102			mtx_unlock(&phys_pager_mtx);
103		} else {
104			if (pindex > object->size)
105				object->size = pindex;
106		}
107		if (phys_pager_alloc_lock == -1)
108			wakeup(&phys_pager_alloc_lock);
109		phys_pager_alloc_lock = 0;
110		mtx_unlock(&Giant);
111	} else {
112		object = vm_object_allocate(OBJT_PHYS, pindex);
113	}
114
115	return (object);
116}
117
118/*
119 * MPSAFE
120 */
121static void
122phys_pager_dealloc(vm_object_t object)
123{
124
125	if (object->handle != NULL) {
126		mtx_lock(&phys_pager_mtx);
127		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
128		mtx_unlock(&phys_pager_mtx);
129	}
130}
131
132/*
133 * Fill as many pages as vm_fault has allocated for us.
134 */
135static int
136phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
137{
138	int i;
139
140	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
141	for (i = 0; i < count; i++) {
142		if (m[i]->valid == 0) {
143			if ((m[i]->flags & PG_ZERO) == 0)
144				pmap_zero_page(m[i]);
145			m[i]->valid = VM_PAGE_BITS_ALL;
146		}
147		KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
148		    ("phys_pager_getpages: partially valid page %p", m[i]));
149		m[i]->dirty = 0;
150		/* The requested page must remain busy, the others not. */
151		if (reqpage != i) {
152			m[i]->oflags &= ~VPO_BUSY;
153			m[i]->busy = 0;
154		}
155	}
156	return (VM_PAGER_OK);
157}
158
159static void
160phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
161		    int *rtvals)
162{
163
164	panic("phys_pager_putpage called");
165}
166
167/*
168 * Implement a pretty aggressive clustered getpages strategy.  Hint that
169 * everything in an entire 4MB window should be prefaulted at once.
170 *
171 * XXX 4MB (1024 slots per page table page) is convenient for x86,
172 * but may not be for other arches.
173 */
174#ifndef PHYSCLUSTER
175#define PHYSCLUSTER 1024
176#endif
177static boolean_t
178phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
179		   int *after)
180{
181	vm_pindex_t base, end;
182
183	base = pindex & (~(PHYSCLUSTER - 1));
184	end = base + (PHYSCLUSTER - 1);
185	if (before != NULL)
186		*before = pindex - base;
187	if (after != NULL)
188		*after = end - pindex;
189	return (TRUE);
190}
191
192struct pagerops physpagerops = {
193	.pgo_init =	phys_pager_init,
194	.pgo_alloc =	phys_pager_alloc,
195	.pgo_dealloc = 	phys_pager_dealloc,
196	.pgo_getpages =	phys_pager_getpages,
197	.pgo_putpages =	phys_pager_putpages,
198	.pgo_haspage =	phys_pager_haspage,
199};
200