1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2003 Peter Wemm.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * the Systems Programming Group of the University of Utah Computer
9 * Science Department and William Jolitz of UUNET Technologies Inc.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 * may be used to endorse or promote products derived from this software
21 * without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 #ifndef __SYS__PV_ENTRY_H__
37 #define __SYS__PV_ENTRY_H__
38
39 #include <sys/param.h>
40
41 struct pmap;
42
43 /*
44 * For each vm_page_t, there is a list of all currently valid virtual
45 * mappings of that page. An entry is a pv_entry_t, the list is pv_list.
46 */
47 typedef struct pv_entry {
48 vm_offset_t pv_va; /* virtual address for mapping */
49 TAILQ_ENTRY(pv_entry) pv_next;
50 } *pv_entry_t;
51
52 /*
53 * pv_entries are allocated in chunks per-process. This avoids the
54 * need to track per-pmap assignments. Each chunk is the size of a
55 * single page.
56 *
57 * Chunks store a bitmap in pc_map[] to track which entries in the
58 * bitmap are free (1) or used (0). PC_FREEL is the value of the last
59 * entry in the pc_map[] array when a chunk is completely free. PC_FREEN
60 * is the value of all the other entries in the pc_map[] array when a
61 * chunk is completely free.
62 */
63 #if PAGE_SIZE == 4 * 1024
64 #ifdef __LP64__
65 #define _NPCPV 168
66 #define _NPAD 0
67 #else
68 #define _NPCPV 336
69 #define _NPAD 0
70 #endif
71 #elif PAGE_SIZE == 16 * 1024
72 #ifdef __LP64__
73 #define _NPCPV 677
74 #define _NPAD 1
75 #endif
76 #endif
77
78 #ifndef _NPCPV
79 #error Unsupported page size
80 #endif
81
82 /* Support clang < 14 */
83 #ifndef __LONG_WIDTH__
84 #define __LONG_WIDTH__ (__CHAR_BIT__ * __SIZEOF_LONG__)
85 #endif
86
87 #define _NPCM howmany(_NPCPV, __LONG_WIDTH__)
88 #define PC_FREEN ~0ul
89 #define PC_FREEL ((1ul << (_NPCPV % __LONG_WIDTH__)) - 1)
90
91 #define PV_CHUNK_HEADER \
92 struct pmap *pc_pmap; \
93 TAILQ_ENTRY(pv_chunk) pc_list; \
94 unsigned long pc_map[_NPCM]; /* bitmap; 1 = free */ \
95 TAILQ_ENTRY(pv_chunk) pc_lru;
96
97 struct pv_chunk_header {
98 PV_CHUNK_HEADER
99 };
100
101 struct pv_chunk {
102 PV_CHUNK_HEADER
103 struct pv_entry pc_pventry[_NPCPV];
104 unsigned long pc_pad[_NPAD];
105 };
106
107 _Static_assert(sizeof(struct pv_chunk) == PAGE_SIZE,
108 "PV entry chunk size mismatch");
109
110 #ifdef _KERNEL
111 static __inline bool
pc_is_full(struct pv_chunk * pc)112 pc_is_full(struct pv_chunk *pc)
113 {
114 for (u_int i = 0; i < _NPCM; i++) {
115 if (pc->pc_map[i] != 0)
116 return (false);
117 }
118 return (true);
119 }
120
121 static __inline bool
pc_is_free(struct pv_chunk * pc)122 pc_is_free(struct pv_chunk *pc)
123 {
124 for (u_int i = 0; i < _NPCM - 1; i++) {
125 if (pc->pc_map[i] != PC_FREEN)
126 return (false);
127 }
128 return (pc->pc_map[_NPCM - 1] == PC_FREEL);
129 }
130
131 static __inline struct pv_chunk *
pv_to_chunk(pv_entry_t pv)132 pv_to_chunk(pv_entry_t pv)
133 {
134 return ((struct pv_chunk *)((uintptr_t)pv & ~(uintptr_t)PAGE_MASK));
135 }
136
137 #define PV_PMAP(pv) (pv_to_chunk(pv)->pc_pmap)
138 #endif
139
140 #endif /* !__SYS__PV_ENTRY_H__ */
141