phys_pager.c revision 76166 
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 76166 2001-05-01 08:13:21Z markm $
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#include <sys/sx.h>
38
39#include <vm/vm.h>
40#include <vm/vm_object.h>
41#include <vm/vm_page.h>
42#include <vm/vm_pager.h>
43#include <vm/vm_zone.h>
44
45/* prevent concurrant creation races */
46static struct sx phys_pager_sx;
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	sx_init(&phys_pager_sx, "phys_pager create");
58	mtx_init(&phys_pager_mtx, "phys_pager list", MTX_DEF);
59}
60
61static vm_object_t
62phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
63		 vm_ooffset_t foff)
64{
65	vm_object_t object;
66
67	/*
68	 * Offset should be page aligned.
69	 */
70	if (foff & PAGE_MASK)
71		return (NULL);
72
73	size = round_page(size);
74
75	if (handle != NULL) {
76		/*
77		 * Lock to prevent object creation race condition.
78		 */
79		sx_xlock(&phys_pager_sx);
80
81		/*
82		 * Look up pager, creating as necessary.
83		 */
84		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
85		if (object == NULL) {
86			/*
87			 * Allocate object and associate it with the pager.
88			 */
89			object = vm_object_allocate(OBJT_PHYS,
90				OFF_TO_IDX(foff + size));
91			object->handle = handle;
92			mtx_lock(&phys_pager_mtx);
93			TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
94			    pager_object_list);
95			mtx_unlock(&phys_pager_mtx);
96		} else {
97			/*
98			 * Gain a reference to the object.
99			 */
100			vm_object_reference(object);
101			if (OFF_TO_IDX(foff + size) > object->size)
102				object->size = OFF_TO_IDX(foff + size);
103		}
104		sx_xunlock(&phys_pager_sx);
105	} else {
106		object = vm_object_allocate(OBJT_PHYS,
107			OFF_TO_IDX(foff + size));
108	}
109
110	return (object);
111}
112
113static void
114phys_pager_dealloc(vm_object_t object)
115{
116
117	if (object->handle != NULL) {
118		mtx_lock(&phys_pager_mtx);
119		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
120		mtx_unlock(&phys_pager_mtx);
121	}
122}
123
124static int
125phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
126{
127	int i, s;
128
129	s = splvm();
130	/*
131	 * Fill as many pages as vm_fault has allocated for us.
132	 */
133	for (i = 0; i < count; i++) {
134		if ((m[i]->flags & PG_ZERO) == 0)
135			vm_page_zero_fill(m[i]);
136		vm_page_flag_set(m[i], PG_ZERO);
137		/* Switch off pv_entries */
138		vm_page_unmanage(m[i]);
139		m[i]->valid = VM_PAGE_BITS_ALL;
140		m[i]->dirty = 0;
141		/* The requested page must remain busy, the others not. */
142		if (reqpage != i) {
143			vm_page_flag_clear(m[i], PG_BUSY);
144			m[i]->busy = 0;
145		}
146	}
147	splx(s);
148
149	return (VM_PAGER_OK);
150}
151
152static void
153phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
154		    int *rtvals)
155{
156
157	panic("phys_pager_putpage called");
158}
159
160/*
161 * Implement a pretty aggressive clustered getpages strategy.  Hint that
162 * everything in an entire 4MB window should be prefaulted at once.
163 *
164 * XXX 4MB (1024 slots per page table page) is convenient for x86,
165 * but may not be for other arches.
166 */
167#ifndef PHYSCLUSTER
168#define PHYSCLUSTER 1024
169#endif
170static boolean_t
171phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
172		   int *after)
173{
174	vm_pindex_t base, end;
175
176	base = pindex & (~(PHYSCLUSTER - 1));
177	end = base + (PHYSCLUSTER - 1);
178	if (before != NULL)
179		*before = pindex - base;
180	if (after != NULL)
181		*after = end - pindex;
182	return (TRUE);
183}
184
185struct pagerops physpagerops = {
186	phys_pager_init,
187	phys_pager_alloc,
188	phys_pager_dealloc,
189	phys_pager_getpages,
190	phys_pager_putpages,
191	phys_pager_haspage,
192	NULL
193};
194