phys_pager.c revision 93818 
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 93818 2002-04-04 21:03:38Z 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/proc.h>
35#include <sys/mutex.h>
36#include <sys/mman.h>
37#include <sys/sysctl.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
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", NULL, 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	GIANT_REQUIRED;
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		while (phys_pager_alloc_lock) {
80			phys_pager_alloc_lock = -1;
81			tsleep(&phys_pager_alloc_lock, PVM, "swpalc", 0);
82		}
83		phys_pager_alloc_lock = 1;
84
85		/*
86		 * Look up pager, creating as necessary.
87		 */
88		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
89		if (object == NULL) {
90			/*
91			 * Allocate object and associate it with the pager.
92			 */
93			object = vm_object_allocate(OBJT_PHYS,
94				OFF_TO_IDX(foff + size));
95			object->handle = handle;
96			mtx_lock(&phys_pager_mtx);
97			TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
98			    pager_object_list);
99			mtx_unlock(&phys_pager_mtx);
100		} else {
101			/*
102			 * Gain a reference to the object.
103			 */
104			vm_object_reference(object);
105			if (OFF_TO_IDX(foff + size) > object->size)
106				object->size = OFF_TO_IDX(foff + size);
107		}
108		if (phys_pager_alloc_lock == -1)
109			wakeup(&phys_pager_alloc_lock);
110		phys_pager_alloc_lock = 0;
111
112	} else {
113		object = vm_object_allocate(OBJT_PHYS,
114			OFF_TO_IDX(foff + size));
115	}
116
117	return (object);
118}
119
120static void
121phys_pager_dealloc(vm_object_t object)
122{
123
124	if (object->handle != NULL) {
125		mtx_lock(&phys_pager_mtx);
126		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
127		mtx_unlock(&phys_pager_mtx);
128	}
129}
130
131static int
132phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
133{
134	int i, s;
135
136	s = splvm();
137	/*
138	 * Fill as many pages as vm_fault has allocated for us.
139	 */
140	for (i = 0; i < count; i++) {
141		if ((m[i]->flags & PG_ZERO) == 0)
142			vm_page_zero_fill(m[i]);
143		vm_page_flag_set(m[i], PG_ZERO);
144		/* Switch off pv_entries */
145		vm_page_unmanage(m[i]);
146		m[i]->valid = VM_PAGE_BITS_ALL;
147		m[i]->dirty = 0;
148		/* The requested page must remain busy, the others not. */
149		if (reqpage != i) {
150			vm_page_flag_clear(m[i], PG_BUSY);
151			m[i]->busy = 0;
152		}
153	}
154	splx(s);
155
156	return (VM_PAGER_OK);
157}
158
159static void
160phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
161		    int *rtvals)
162{
163
164	panic("phys_pager_putpage called");
165}
166
167/*
168 * Implement a pretty aggressive clustered getpages strategy.  Hint that
169 * everything in an entire 4MB window should be prefaulted at once.
170 *
171 * XXX 4MB (1024 slots per page table page) is convenient for x86,
172 * but may not be for other arches.
173 */
174#ifndef PHYSCLUSTER
175#define PHYSCLUSTER 1024
176#endif
177static boolean_t
178phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
179		   int *after)
180{
181	vm_pindex_t base, end;
182
183	base = pindex & (~(PHYSCLUSTER - 1));
184	end = base + (PHYSCLUSTER - 1);
185	if (before != NULL)
186		*before = pindex - base;
187	if (after != NULL)
188		*after = end - pindex;
189	return (TRUE);
190}
191
192struct pagerops physpagerops = {
193	phys_pager_init,
194	phys_pager_alloc,
195	phys_pager_dealloc,
196	phys_pager_getpages,
197	phys_pager_putpages,
198	phys_pager_haspage,
199	NULL
200};
201