phys_pager.c revision 75675 
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 75675 2001-04-18 20:24:16Z 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/mman.h>
34#include <sys/sysctl.h>
35#include <sys/sx.h>
36
37#include <vm/vm.h>
38#include <vm/vm_object.h>
39#include <vm/vm_page.h>
40#include <vm/vm_pager.h>
41#include <vm/vm_zone.h>
42
43/* prevent concurrant creation races */
44static struct sx phys_pager_sx;
45/* list of device pager objects */
46static struct pagerlst phys_pager_object_list;
47/* protect access to phys_pager_object_list */
48static struct mtx phys_pager_mtx;
49
50static void
51phys_pager_init(void)
52{
53
54	TAILQ_INIT(&phys_pager_object_list);
55	sx_init(&phys_pager_sx, "phys_pager create");
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		sx_xlock(&phys_pager_sx);
78
79		/*
80		 * Look up pager, creating as necessary.
81		 */
82		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
83		if (object == NULL) {
84			/*
85			 * Allocate object and associate it with the pager.
86			 */
87			object = vm_object_allocate(OBJT_PHYS,
88				OFF_TO_IDX(foff + size));
89			object->handle = handle;
90			mtx_lock(&phys_pager_mtx);
91			TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
92			    pager_object_list);
93			mtx_unlock(&phys_pager_mtx);
94		} else {
95			/*
96			 * Gain a reference to the object.
97			 */
98			vm_object_reference(object);
99			if (OFF_TO_IDX(foff + size) > object->size)
100				object->size = OFF_TO_IDX(foff + size);
101		}
102		sx_xunlock(&phys_pager_sx);
103	} else {
104		object = vm_object_allocate(OBJT_PHYS,
105			OFF_TO_IDX(foff + size));
106	}
107
108	return (object);
109}
110
111static void
112phys_pager_dealloc(vm_object_t object)
113{
114
115	if (object->handle != NULL) {
116		mtx_lock(&phys_pager_mtx);
117		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
118		mtx_unlock(&phys_pager_mtx);
119	}
120}
121
122static int
123phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
124{
125	int i, s;
126
127	s = splvm();
128	/*
129	 * Fill as many pages as vm_fault has allocated for us.
130	 */
131	for (i = 0; i < count; i++) {
132		if ((m[i]->flags & PG_ZERO) == 0)
133			vm_page_zero_fill(m[i]);
134		vm_page_flag_set(m[i], PG_ZERO);
135		/* Switch off pv_entries */
136		vm_page_unmanage(m[i]);
137		m[i]->valid = VM_PAGE_BITS_ALL;
138		m[i]->dirty = 0;
139		/* The requested page must remain busy, the others not. */
140		if (reqpage != i) {
141			vm_page_flag_clear(m[i], PG_BUSY);
142			m[i]->busy = 0;
143		}
144	}
145	splx(s);
146
147	return (VM_PAGER_OK);
148}
149
150static void
151phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
152		    int *rtvals)
153{
154
155	panic("phys_pager_putpage called");
156}
157
158/*
159 * Implement a pretty aggressive clustered getpages strategy.  Hint that
160 * everything in an entire 4MB window should be prefaulted at once.
161 *
162 * XXX 4MB (1024 slots per page table page) is convenient for x86,
163 * but may not be for other arches.
164 */
165#ifndef PHYSCLUSTER
166#define PHYSCLUSTER 1024
167#endif
168static boolean_t
169phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
170		   int *after)
171{
172	vm_pindex_t base, end;
173
174	base = pindex & (~(PHYSCLUSTER - 1));
175	end = base + (PHYSCLUSTER - 1);
176	if (before != NULL)
177		*before = pindex - base;
178	if (after != NULL)
179		*after = end - pindex;
180	return (TRUE);
181}
182
183struct pagerops physpagerops = {
184	phys_pager_init,
185	phys_pager_alloc,
186	phys_pager_dealloc,
187	phys_pager_getpages,
188	phys_pager_putpages,
189	phys_pager_haspage,
190	NULL
191};
192