phys_pager.c revision 69687 
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 * $FreeBSD: head/sys/vm/phys_pager.c 69687 2000-12-06 21:52:23Z alfred $
26 */
27
28#include <sys/param.h>
29#include <sys/systm.h>
30#include <sys/linker_set.h>
31#include <sys/conf.h>
32#include <sys/mman.h>
33#include <sys/sysctl.h>
34
35#include <vm/vm.h>
36#include <vm/vm_object.h>
37#include <vm/vm_page.h>
38#include <vm/vm_pager.h>
39#include <vm/vm_zone.h>
40
41/* list of device pager objects */
42static struct pagerlst phys_pager_object_list;
43
44static int phys_pager_alloc_lock, phys_pager_alloc_lock_want;
45
46static void
47phys_pager_init(void)
48{
49
50	TAILQ_INIT(&phys_pager_object_list);
51}
52
53static vm_object_t
54phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
55		 vm_ooffset_t foff)
56{
57	vm_object_t object;
58
59	/*
60	 * Offset should be page aligned.
61	 */
62	if (foff & PAGE_MASK)
63		return (NULL);
64
65	size = round_page(size);
66
67	if (handle != NULL) {
68		/*
69		 * Lock to prevent object creation race condition.
70		 */
71		while (phys_pager_alloc_lock) {
72			phys_pager_alloc_lock_want++;
73			tsleep(&phys_pager_alloc_lock, PVM, "ppall", 0);
74			phys_pager_alloc_lock_want--;
75		}
76		phys_pager_alloc_lock = 1;
77
78		/*
79		 * Look up pager, creating as necessary.
80		 */
81		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
82		if (object == NULL) {
83			/*
84			 * Allocate object and associate it with the pager.
85			 */
86			object = vm_object_allocate(OBJT_PHYS,
87				OFF_TO_IDX(foff + size));
88			object->handle = handle;
89			TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
90			    pager_object_list);
91		} else {
92			/*
93			 * Gain a reference to the object.
94			 */
95			vm_object_reference(object);
96			if (OFF_TO_IDX(foff + size) > object->size)
97				object->size = OFF_TO_IDX(foff + size);
98		}
99		phys_pager_alloc_lock = 0;
100		if (phys_pager_alloc_lock_want)
101			wakeup(&phys_pager_alloc_lock);
102	} else {
103		object = vm_object_allocate(OBJT_PHYS,
104			OFF_TO_IDX(foff + size));
105	}
106
107	return (object);
108}
109
110static void
111phys_pager_dealloc(vm_object_t object)
112{
113
114	if (object->handle != NULL)
115		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
116}
117
118static int
119phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
120{
121	int i, s;
122
123	s = splvm();
124	/*
125	 * Fill as many pages as vm_fault has allocated for us.
126	 */
127	for (i = 0; i < count; i++) {
128		if ((m[i]->flags & PG_ZERO) == 0)
129			vm_page_zero_fill(m[i]);
130		vm_page_flag_set(m[i], PG_ZERO);
131		/* Switch off pv_entries */
132		vm_page_unmanage(m[i]);
133		m[i]->valid = VM_PAGE_BITS_ALL;
134		m[i]->dirty = 0;
135		/* The requested page must remain busy, the others not. */
136		if (reqpage != i) {
137			vm_page_flag_clear(m[i], PG_BUSY);
138			m[i]->busy = 0;
139		}
140	}
141	splx(s);
142
143	return (VM_PAGER_OK);
144}
145
146static void
147phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
148		    int *rtvals)
149{
150
151	panic("phys_pager_putpage called");
152}
153
154/*
155 * Implement a pretty aggressive clustered getpages strategy.  Hint that
156 * everything in an entire 4MB window should be prefaulted at once.
157 *
158 * XXX 4MB (1024 slots per page table page) is convenient for x86,
159 * but may not be for other arches.
160 */
161#ifndef PHYSCLUSTER
162#define PHYSCLUSTER 1024
163#endif
164static boolean_t
165phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
166		   int *after)
167{
168	vm_pindex_t base, end;
169
170	base = pindex & (~(PHYSCLUSTER - 1));
171	end = base + (PHYSCLUSTER - 1);
172	if (before != NULL)
173		*before = pindex - base;
174	if (after != NULL)
175		*after = end - pindex;
176	return (TRUE);
177}
178
179struct pagerops physpagerops = {
180	phys_pager_init,
181	phys_pager_alloc,
182	phys_pager_dealloc,
183	phys_pager_getpages,
184	phys_pager_putpages,
185	phys_pager_haspage,
186	NULL
187};
188