phys_pager.c revision 76827 
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 76827 2001-05-19 01:28:09Z 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/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
82		/*
83		 * Look up pager, creating as necessary.
84		 */
85		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
86		if (object == NULL) {
87			/*
88			 * Allocate object and associate it with the pager.
89			 */
90			object = vm_object_allocate(OBJT_PHYS,
91				OFF_TO_IDX(foff + size));
92			object->handle = handle;
93			mtx_lock(&phys_pager_mtx);
94			TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
95			    pager_object_list);
96			mtx_unlock(&phys_pager_mtx);
97		} else {
98			/*
99			 * Gain a reference to the object.
100			 */
101			vm_object_reference(object);
102			if (OFF_TO_IDX(foff + size) > object->size)
103				object->size = OFF_TO_IDX(foff + size);
104		}
105		if (phys_pager_alloc_lock)
106			wakeup(&phys_pager_alloc_lock);
107		phys_pager_alloc_lock = 0;
108
109	} else {
110		object = vm_object_allocate(OBJT_PHYS,
111			OFF_TO_IDX(foff + size));
112	}
113
114	return (object);
115}
116
117static void
118phys_pager_dealloc(vm_object_t object)
119{
120
121	if (object->handle != NULL) {
122		mtx_lock(&phys_pager_mtx);
123		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
124		mtx_unlock(&phys_pager_mtx);
125	}
126}
127
128static int
129phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
130{
131	int i, s;
132
133	s = splvm();
134	/*
135	 * Fill as many pages as vm_fault has allocated for us.
136	 */
137	for (i = 0; i < count; i++) {
138		if ((m[i]->flags & PG_ZERO) == 0)
139			vm_page_zero_fill(m[i]);
140		vm_page_flag_set(m[i], PG_ZERO);
141		/* Switch off pv_entries */
142		vm_page_unmanage(m[i]);
143		m[i]->valid = VM_PAGE_BITS_ALL;
144		m[i]->dirty = 0;
145		/* The requested page must remain busy, the others not. */
146		if (reqpage != i) {
147			vm_page_flag_clear(m[i], PG_BUSY);
148			m[i]->busy = 0;
149		}
150	}
151	splx(s);
152
153	return (VM_PAGER_OK);
154}
155
156static void
157phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
158		    int *rtvals)
159{
160
161	panic("phys_pager_putpage called");
162}
163
164/*
165 * Implement a pretty aggressive clustered getpages strategy.  Hint that
166 * everything in an entire 4MB window should be prefaulted at once.
167 *
168 * XXX 4MB (1024 slots per page table page) is convenient for x86,
169 * but may not be for other arches.
170 */
171#ifndef PHYSCLUSTER
172#define PHYSCLUSTER 1024
173#endif
174static boolean_t
175phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
176		   int *after)
177{
178	vm_pindex_t base, end;
179
180	base = pindex & (~(PHYSCLUSTER - 1));
181	end = base + (PHYSCLUSTER - 1);
182	if (before != NULL)
183		*before = pindex - base;
184	if (after != NULL)
185		*after = end - pindex;
186	return (TRUE);
187}
188
189struct pagerops physpagerops = {
190	phys_pager_init,
191	phys_pager_alloc,
192	phys_pager_dealloc,
193	phys_pager_getpages,
194	phys_pager_putpages,
195	phys_pager_haspage,
196	NULL
197};
198