xref: /freebsd/sys/vm/phys_pager.c (revision 85999a0155e389415cc476110fd5614baf543a55)
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("$FreeBSD$");
28 
29 #include <sys/param.h>
30 #include <sys/systm.h>
31 #include <sys/linker_set.h>
32 #include <sys/conf.h>
33 #include <sys/kernel.h>
34 #include <sys/lock.h>
35 #include <sys/proc.h>
36 #include <sys/mutex.h>
37 #include <sys/mman.h>
38 #include <sys/sysctl.h>
39 
40 #include <vm/vm.h>
41 #include <vm/vm_object.h>
42 #include <vm/vm_page.h>
43 #include <vm/vm_pager.h>
44 
45 /* prevent concurrent creation races */
46 static int phys_pager_alloc_lock;
47 /* list of device pager objects */
48 static struct pagerlst phys_pager_object_list;
49 /* protect access to phys_pager_object_list */
50 static struct mtx phys_pager_mtx;
51 
52 static void
53 phys_pager_init(void)
54 {
55 
56 	TAILQ_INIT(&phys_pager_object_list);
57 	mtx_init(&phys_pager_mtx, "phys_pager list", NULL, MTX_DEF);
58 }
59 
60 /*
61  * MPSAFE
62  */
63 static vm_object_t
64 phys_pager_alloc(void *handle, vm_ooffset_t size, vm_prot_t prot,
65 		 vm_ooffset_t foff)
66 {
67 	vm_object_t object;
68 	vm_pindex_t pindex;
69 
70 	/*
71 	 * Offset should be page aligned.
72 	 */
73 	if (foff & PAGE_MASK)
74 		return (NULL);
75 
76 	pindex = OFF_TO_IDX(foff + PAGE_MASK + size);
77 
78 	if (handle != NULL) {
79 		mtx_lock(&Giant);
80 		/*
81 		 * Lock to prevent object creation race condition.
82 		 */
83 		while (phys_pager_alloc_lock) {
84 			phys_pager_alloc_lock = -1;
85 			tsleep(&phys_pager_alloc_lock, PVM, "swpalc", 0);
86 		}
87 		phys_pager_alloc_lock = 1;
88 
89 		/*
90 		 * Look up pager, creating as necessary.
91 		 */
92 		object = vm_pager_object_lookup(&phys_pager_object_list, handle);
93 		if (object == NULL) {
94 			/*
95 			 * Allocate object and associate it with the pager.
96 			 */
97 			object = vm_object_allocate(OBJT_PHYS, pindex);
98 			object->handle = handle;
99 			mtx_lock(&phys_pager_mtx);
100 			TAILQ_INSERT_TAIL(&phys_pager_object_list, object,
101 			    pager_object_list);
102 			mtx_unlock(&phys_pager_mtx);
103 		} else {
104 			/*
105 			 * Gain a reference to the object.
106 			 */
107 			vm_object_reference(object);
108 			if (pindex > object->size)
109 				object->size = pindex;
110 		}
111 		if (phys_pager_alloc_lock == -1)
112 			wakeup(&phys_pager_alloc_lock);
113 		phys_pager_alloc_lock = 0;
114 		mtx_unlock(&Giant);
115 	} else {
116 		object = vm_object_allocate(OBJT_PHYS, pindex);
117 	}
118 
119 	return (object);
120 }
121 
122 /*
123  * MPSAFE
124  */
125 static void
126 phys_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 
136 /*
137  * Fill as many pages as vm_fault has allocated for us.
138  */
139 static int
140 phys_pager_getpages(vm_object_t object, vm_page_t *m, int count, int reqpage)
141 {
142 	int i;
143 
144 	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
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 		m[i]->dirty = 0;
154 		/* The requested page must remain busy, the others not. */
155 		if (reqpage != i) {
156 			m[i]->oflags &= ~VPO_BUSY;
157 			m[i]->busy = 0;
158 		}
159 	}
160 	return (VM_PAGER_OK);
161 }
162 
163 static void
164 phys_pager_putpages(vm_object_t object, vm_page_t *m, int count, boolean_t sync,
165 		    int *rtvals)
166 {
167 
168 	panic("phys_pager_putpage called");
169 }
170 
171 /*
172  * Implement a pretty aggressive clustered getpages strategy.  Hint that
173  * everything in an entire 4MB window should be prefaulted at once.
174  *
175  * XXX 4MB (1024 slots per page table page) is convenient for x86,
176  * but may not be for other arches.
177  */
178 #ifndef PHYSCLUSTER
179 #define PHYSCLUSTER 1024
180 #endif
181 static boolean_t
182 phys_pager_haspage(vm_object_t object, vm_pindex_t pindex, int *before,
183 		   int *after)
184 {
185 	vm_pindex_t base, end;
186 
187 	base = pindex & (~(PHYSCLUSTER - 1));
188 	end = base + (PHYSCLUSTER - 1);
189 	if (before != NULL)
190 		*before = pindex - base;
191 	if (after != NULL)
192 		*after = end - pindex;
193 	return (TRUE);
194 }
195 
196 struct pagerops physpagerops = {
197 	.pgo_init =	phys_pager_init,
198 	.pgo_alloc =	phys_pager_alloc,
199 	.pgo_dealloc = 	phys_pager_dealloc,
200 	.pgo_getpages =	phys_pager_getpages,
201 	.pgo_putpages =	phys_pager_putpages,
202 	.pgo_haspage =	phys_pager_haspage,
203 };
204