phys_pager.c revision 77062 
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 77062 2001-05-23 19:52:23Z jhb $
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/kernel.h>
33#include <sys/lock.h>
34#include <sys/mutex.h>
35#include <sys/mman.h>
36#include <sys/sysctl.h>
37
38#include <vm/vm.h>
39#include <vm/vm_object.h>
40#include <vm/vm_page.h>
41#include <vm/vm_pager.h>
42#include <vm/vm_zone.h>
43
44/* prevent concurrant creation races */
45static int phys_pager_alloc_lock;
46/* list of device pager objects */
47static struct pagerlst phys_pager_object_list;
48/* protect access to phys_pager_object_list */
49static struct mtx phys_pager_mtx;
50
51static void
52phys_pager_init(void)
53{
54
55	TAILQ_INIT(&phys_pager_object_list);
56	mtx_init(&phys_pager_mtx, "phys_pager list", MTX_DEF);
57}
58
59static vm_object_t
60phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
61		 vm_ooffset_t foff)
62{
63	vm_object_t object;
64
65	/*
66	 * Offset should be page aligned.
67	 */
68	if (foff & PAGE_MASK)
69		return (NULL);
70
71	size = round_page(size);
72
73	if (handle != NULL) {
74		/*
75		 * Lock to prevent object creation race condition.
76		 */
77		while (phys_pager_alloc_lock) {
78			phys_pager_alloc_lock = -1;
79			msleep(&phys_pager_alloc_lock, &vm_mtx, PVM, "swpalc", 0);
80		}
81		phys_pager_alloc_lock = 1;
82
83		/*
84		 * Look up pager, creating as necessary.
85		 */
86		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
87		if (object == NULL) {
88			/*
89			 * Allocate object and associate it with the pager.
90			 */
91			object = vm_object_allocate(OBJT_PHYS,
92				OFF_TO_IDX(foff + size));
93			object->handle = handle;
94			mtx_lock(&phys_pager_mtx);
95			TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
96			    pager_object_list);
97			mtx_unlock(&phys_pager_mtx);
98		} else {
99			/*
100			 * Gain a reference to the object.
101			 */
102			vm_object_reference(object);
103			if (OFF_TO_IDX(foff + size) > object->size)
104				object->size = OFF_TO_IDX(foff + size);
105		}
106		if (phys_pager_alloc_lock == -1)
107			wakeup(&phys_pager_alloc_lock);
108		phys_pager_alloc_lock = 0;
109
110	} else {
111		object = vm_object_allocate(OBJT_PHYS,
112			OFF_TO_IDX(foff + size));
113	}
114
115	return (object);
116}
117
118static void
119phys_pager_dealloc(vm_object_t object)
120{
121
122	if (object->handle != NULL) {
123		mtx_lock(&phys_pager_mtx);
124		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
125		mtx_unlock(&phys_pager_mtx);
126	}
127}
128
129static int
130phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
131{
132	int i, s;
133
134	s = splvm();
135	/*
136	 * Fill as many pages as vm_fault has allocated for us.
137	 */
138	for (i = 0; i < count; i++) {
139		if ((m[i]->flags & PG_ZERO) == 0)
140			vm_page_zero_fill(m[i]);
141		vm_page_flag_set(m[i], PG_ZERO);
142		/* Switch off pv_entries */
143		vm_page_unmanage(m[i]);
144		m[i]->valid = VM_PAGE_BITS_ALL;
145		m[i]->dirty = 0;
146		/* The requested page must remain busy, the others not. */
147		if (reqpage != i) {
148			vm_page_flag_clear(m[i], PG_BUSY);
149			m[i]->busy = 0;
150		}
151	}
152	splx(s);
153
154	return (VM_PAGER_OK);
155}
156
157static void
158phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
159		    int *rtvals)
160{
161
162	panic("phys_pager_putpage called");
163}
164
165/*
166 * Implement a pretty aggressive clustered getpages strategy.  Hint that
167 * everything in an entire 4MB window should be prefaulted at once.
168 *
169 * XXX 4MB (1024 slots per page table page) is convenient for x86,
170 * but may not be for other arches.
171 */
172#ifndef PHYSCLUSTER
173#define PHYSCLUSTER 1024
174#endif
175static boolean_t
176phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
177		   int *after)
178{
179	vm_pindex_t base, end;
180
181	base = pindex & (~(PHYSCLUSTER - 1));
182	end = base + (PHYSCLUSTER - 1);
183	if (before != NULL)
184		*before = pindex - base;
185	if (after != NULL)
186		*after = end - pindex;
187	return (TRUE);
188}
189
190struct pagerops physpagerops = {
191	phys_pager_init,
192	phys_pager_alloc,
193	phys_pager_dealloc,
194	phys_pager_getpages,
195	phys_pager_putpages,
196	phys_pager_haspage,
197	NULL
198};
199