phys_pager.c revision 108306 
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 108306 2002-12-27 06:09:56Z alc $
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
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)
65{
66	vm_object_t object;
67
68	/*
69	 * Offset should be page aligned.
70	 */
71	if (foff & PAGE_MASK)
72		return (NULL);
73
74	size = round_page(size);
75
76	if (handle != NULL) {
77		mtx_lock(&Giant);
78		/*
79		 * Lock to prevent object creation race condition.
80		 */
81		while (phys_pager_alloc_lock) {
82			phys_pager_alloc_lock = -1;
83			tsleep(&phys_pager_alloc_lock, PVM, "swpalc", 0);
84		}
85		phys_pager_alloc_lock = 1;
86
87		/*
88		 * Look up pager, creating as necessary.
89		 */
90		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
91		if (object == NULL) {
92			/*
93			 * Allocate object and associate it with the pager.
94			 */
95			object = vm_object_allocate(OBJT_PHYS,
96				OFF_TO_IDX(foff + size));
97			object->handle = handle;
98			mtx_lock(&phys_pager_mtx);
99			TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
100			    pager_object_list);
101			mtx_unlock(&phys_pager_mtx);
102		} else {
103			/*
104			 * Gain a reference to the object.
105			 */
106			vm_object_reference(object);
107			if (OFF_TO_IDX(foff + size) > object->size)
108				object->size = OFF_TO_IDX(foff + size);
109		}
110		if (phys_pager_alloc_lock == -1)
111			wakeup(&phys_pager_alloc_lock);
112		phys_pager_alloc_lock = 0;
113		mtx_unlock(&Giant);
114	} else {
115		object = vm_object_allocate(OBJT_PHYS,
116			OFF_TO_IDX(foff + size));
117	}
118
119	return (object);
120}
121
122/*
123 * MPSAFE
124 */
125static void
126phys_pager_dealloc(vm_object_t object)
127{
128
129	if (object->handle != NULL) {
130		mtx_lock(&phys_pager_mtx);
131		TAILQ_REMOVE(&phys_pager_object_list, object, pager_object_list);
132		mtx_unlock(&phys_pager_mtx);
133	}
134}
135
136static int
137phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
138{
139	int i, s;
140
141	s = splvm();
142	vm_page_lock_queues();
143	/*
144	 * Fill as many pages as vm_fault has allocated for us.
145	 */
146	for (i = 0; i < count; i++) {
147		if ((m[i]->flags & PG_ZERO) == 0) {
148			vm_page_unlock_queues();
149			pmap_zero_page(m[i]);
150			vm_page_lock_queues();
151		}
152		vm_page_flag_set(m[i], PG_ZERO);
153		/* Switch off pv_entries */
154		vm_page_unmanage(m[i]);
155		m[i]->valid = VM_PAGE_BITS_ALL;
156		m[i]->dirty = 0;
157		/* The requested page must remain busy, the others not. */
158		if (reqpage != i) {
159			vm_page_flag_clear(m[i], PG_BUSY);
160			m[i]->busy = 0;
161		}
162	}
163	vm_page_unlock_queues();
164	splx(s);
165
166	return (VM_PAGER_OK);
167}
168
169static void
170phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
171		    int *rtvals)
172{
173
174	panic("phys_pager_putpage called");
175}
176
177/*
178 * Implement a pretty aggressive clustered getpages strategy.  Hint that
179 * everything in an entire 4MB window should be prefaulted at once.
180 *
181 * XXX 4MB (1024 slots per page table page) is convenient for x86,
182 * but may not be for other arches.
183 */
184#ifndef PHYSCLUSTER
185#define PHYSCLUSTER 1024
186#endif
187static boolean_t
188phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
189		   int *after)
190{
191	vm_pindex_t base, end;
192
193	base = pindex & (~(PHYSCLUSTER - 1));
194	end = base + (PHYSCLUSTER - 1);
195	if (before != NULL)
196		*before = pindex - base;
197	if (after != NULL)
198		*after = end - pindex;
199	return (TRUE);
200}
201
202struct pagerops physpagerops = {
203	phys_pager_init,
204	phys_pager_alloc,
205	phys_pager_dealloc,
206	phys_pager_getpages,
207	phys_pager_putpages,
208	phys_pager_haspage,
209	NULL
210};
211