phys_pager.c revision 254138 
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
26#include <sys/cdefs.h>
27__FBSDID("$FreeBSD: head/sys/vm/phys_pager.c 254138 2013-08-09 11:11:11Z attilio $");
28
29#include <sys/param.h>
30#include <sys/systm.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/rwlock.h>
38#include <sys/sysctl.h>
39
40#include <vm/vm.h>
41#include <vm/vm_param.h>
42#include <vm/vm_object.h>
43#include <vm/vm_page.h>
44#include <vm/vm_pager.h>
45
46/* list of phys 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
59/*
60 * MPSAFE
61 */
62static vm_object_t
63phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
64    vm_ooffset_t foff, struct ucred *cred)
65{
66	vm_object_t object, object1;
67	vm_pindex_t pindex;
68
69	/*
70	 * Offset should be page aligned.
71	 */
72	if (foff & PAGE_MASK)
73		return (NULL);
74
75	pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
76
77	if (handle != NULL) {
78		mtx_lock(&phys_pager_mtx);
79		/*
80		 * Look up pager, creating as necessary.
81		 */
82		object1 = NULL;
83		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
84		if (object == NULL) {
85			/*
86			 * Allocate object and associate it with the pager.
87			 */
88			mtx_unlock(&phys_pager_mtx);
89			object1 = vm_object_allocate(OBJT_PHYS, pindex);
90			mtx_lock(&phys_pager_mtx);
91			object = vm_pager_object_lookup(&phys_pager_object_list,
92			    handle);
93			if (object != NULL) {
94				/*
95				 * We raced with other thread while
96				 * allocating object.
97				 */
98				if (pindex > object->size)
99					object->size = pindex;
100			} else {
101				object = object1;
102				object1 = NULL;
103				object->handle = handle;
104				TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
105				    pager_object_list);
106			}
107		} else {
108			if (pindex > object->size)
109				object->size = pindex;
110		}
111		mtx_unlock(&phys_pager_mtx);
112		vm_object_deallocate(object1);
113	} else {
114		object = vm_object_allocate(OBJT_PHYS, pindex);
115	}
116
117	return (object);
118}
119
120/*
121 * MPSAFE
122 */
123static void
124phys_pager_dealloc(vm_object_t object)
125{
126
127	if (object->handle != NULL) {
128		VM_OBJECT_WUNLOCK(object);
129		mtx_lock(&phys_pager_mtx);
130		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
131		mtx_unlock(&phys_pager_mtx);
132		VM_OBJECT_WLOCK(object);
133	}
134}
135
136/*
137 * Fill as many pages as vm_fault has allocated for us.
138 */
139static int
140phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
141{
142	int i;
143
144	VM_OBJECT_ASSERT_WLOCKED(object);
145	for (i = 0; i < count; i++) {
146		if (m[i]->valid == 0) {
147			if ((m[i]->flags & PG_ZERO) == 0)
148				pmap_zero_page(m[i]);
149			m[i]->valid = VM_PAGE_BITS_ALL;
150		}
151		KASSERT(m[i]->valid == VM_PAGE_BITS_ALL,
152		    ("phys_pager_getpages: partially valid page %p", m[i]));
153		KASSERT(m[i]->dirty == 0,
154		    ("phys_pager_getpages: dirty page %p", m[i]));
155		/* The requested page must remain busy, the others not. */
156		if (i == reqpage) {
157			vm_page_lock(m[i]);
158			vm_page_flash(m[i]);
159			vm_page_unlock(m[i]);
160		} else
161			vm_page_xunbusy(m[i]);
162	}
163	return (VM_PAGER_OK);
164}
165
166static void
167phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
168		    int *rtvals)
169{
170
171	panic("phys_pager_putpage called");
172}
173
174/*
175 * Implement a pretty aggressive clustered getpages strategy.  Hint that
176 * everything in an entire 4MB window should be prefaulted at once.
177 *
178 * XXX 4MB (1024 slots per page table page) is convenient for x86,
179 * but may not be for other arches.
180 */
181#ifndef PHYSCLUSTER
182#define PHYSCLUSTER 1024
183#endif
184static boolean_t
185phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
186		   int *after)
187{
188	vm_pindex_t base, end;
189
190	base = pindex & (~(PHYSCLUSTER - 1));
191	end = base + (PHYSCLUSTER - 1);
192	if (before != NULL)
193		*before = pindex - base;
194	if (after != NULL)
195		*after = end - pindex;
196	return (TRUE);
197}
198
199struct pagerops physpagerops = {
200	.pgo_init =	phys_pager_init,
201	.pgo_alloc =	phys_pager_alloc,
202	.pgo_dealloc = 	phys_pager_dealloc,
203	.pgo_getpages =	phys_pager_getpages,
204	.pgo_putpages =	phys_pager_putpages,
205	.pgo_haspage =	phys_pager_haspage,
206};
207