1 /*
2 * Copyright (c) 2000-2004 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 /*
29 * @OSF_COPYRIGHT@
30 */
31 /*
32 * Mach Operating System
33 * Copyright (c) 1991,1990,1989 Carnegie Mellon University
34 * All Rights Reserved.
35 *
36 * Permission to use, copy, modify and distribute this software and its
37 * documentation is hereby granted, provided that both the copyright
38 * notice and this permission notice appear in all copies of the
39 * software, derivative works or modified versions, and any portions
40 * thereof, and that both notices appear in supporting documentation.
41 *
42 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
43 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
44 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
45 *
46 * Carnegie Mellon requests users of this software to return to
47 *
48 * Software Distribution Coordinator or [email protected]
49 * School of Computer Science
50 * Carnegie Mellon University
51 * Pittsburgh PA 15213-3890
52 *
53 * any improvements or extensions that they make and grant Carnegie Mellon
54 * the rights to redistribute these changes.
55 */
56 /*
57 */
58 /*
59 * File: ipc/ipc_entry.h
60 * Author: Rich Draves
61 * Date: 1989
62 *
63 * Definitions for translation entries, which represent
64 * tasks' capabilities for ports and port sets.
65 */
66
67 #ifndef _IPC_IPC_ENTRY_H_
68 #define _IPC_IPC_ENTRY_H_
69
70 #include <mach/mach_types.h>
71 #include <mach/port.h>
72 #include <mach/kern_return.h>
73
74 #include <kern/kern_types.h>
75 #include <kern/zalloc.h>
76
77 #include <ipc/ipc_types.h>
78
79 /*
80 * Spaces hold capabilities for ipc_object_t's.
81 * Each ipc_entry_t records a capability. Most capabilities have
82 * small names, and the entries are elements of a table.
83 *
84 * The ie_index field of entries in the table implements
85 * a ordered hash table with open addressing and linear probing.
86 *
87 * The ie_dist field holds the distance to the desired spot,
88 * which is used to implement robin-hood hashing.
89 *
90 * This hash table converts (space, object) -> name.
91 * It is used independently of the other fields.
92 *
93 * Free (unallocated) entries in the table have null ie_object
94 * fields. The ie_bits field is zero except for IE_BITS_GEN.
95 * The ie_next (ie_request) field links free entries into a free list.
96 *
97 * The first entry in the table (index 0) is always free.
98 * It is used as the head of the free list.
99 */
100
101 #define IPC_ENTRY_DIST_BITS 12
102 #define IPC_ENTRY_DIST_MAX ((1 << IPC_ENTRY_DIST_BITS) - 1)
103 #ifdef __LP64__
104 #define IPC_ENTRY_INDEX_BITS 32
105 #define IPC_ENTRY_INDEX_MAX (UINT32_MAX)
106 #else
107 #define IPC_ENTRY_INDEX_BITS 20
108 #define IPC_ENTRY_INDEX_MAX ((1 << IPC_ENTRY_INDEX_BITS) - 1)
109 #endif
110
111 struct ipc_entry {
112 union {
113 struct ipc_object *XNU_PTRAUTH_SIGNED_PTR("ipc_entry.ie_object") ie_object;
114 struct ipc_object *XNU_PTRAUTH_SIGNED_PTR("ipc_entry.ie_object") volatile ie_volatile_object;
115 };
116 union {
117 ipc_entry_bits_t ie_bits;
118 ipc_entry_num_t ie_size;
119 };
120 uint32_t ie_dist : IPC_ENTRY_DIST_BITS;
121 mach_port_index_t ie_index : IPC_ENTRY_INDEX_BITS;
122 union {
123 mach_port_index_t ie_next; /* next in freelist, or... */
124 ipc_table_index_t ie_request; /* dead name request notify */
125 };
126 };
127
128 #define IE_REQ_NONE 0 /* no request */
129
130 #define IE_BITS_UREFS_MASK 0x0000ffff /* 16 bits of user-reference */
131 #define IE_BITS_UREFS(bits) ((bits) & IE_BITS_UREFS_MASK)
132
133 #define IE_BITS_TYPE_MASK 0x001f0000 /* 5 bits of capability type */
134 #define IE_BITS_TYPE(bits) ((bits) & IE_BITS_TYPE_MASK)
135
136 #define IE_BITS_EXTYPE_MASK 0x00200000 /* 1 bit for extended capability */
137
138 #ifndef NO_PORT_GEN
139 #define IE_BITS_GEN_MASK 0xff000000 /* 8 bits for generation */
140 #define IE_BITS_GEN(bits) ((bits) & IE_BITS_GEN_MASK)
141 #define IE_BITS_GEN_ONE 0x04000000 /* low bit of generation */
142 #define IE_BITS_ROLL_POS 22 /* LSB pos of generation rollover */
143 #define IE_BITS_ROLL_BITS 2 /* number of generation rollover bits */
144 #define IE_BITS_ROLL_MASK (((1 << IE_BITS_ROLL_BITS) - 1) << IE_BITS_ROLL_POS)
145 #define IE_BITS_ROLL(bits) ((((bits) & IE_BITS_ROLL_MASK) << 8) ^ IE_BITS_GEN_MASK)
146
147 /*
148 * Restart a generation counter with the specified bits for the rollover point.
149 * There are 4 different rollover points:
150 * bits rollover period
151 * 0 0 64
152 * 0 1 48
153 * 1 0 32
154 * 1 1 16
155 */
156 static inline ipc_entry_bits_t
ipc_entry_new_rollpoint(ipc_entry_bits_t rollbits)157 ipc_entry_new_rollpoint(
158 ipc_entry_bits_t rollbits)
159 {
160 rollbits = (rollbits << IE_BITS_ROLL_POS) & IE_BITS_ROLL_MASK;
161 ipc_entry_bits_t newgen = IE_BITS_GEN_MASK + IE_BITS_GEN_ONE;
162 return newgen | rollbits;
163 }
164
165 /*
166 * Get the next gencount, modulo the entry's rollover point. If the sum rolls over,
167 * the caller should re-start the generation counter with a different rollpoint.
168 */
169 static inline ipc_entry_bits_t
ipc_entry_new_gen(ipc_entry_bits_t oldgen)170 ipc_entry_new_gen(
171 ipc_entry_bits_t oldgen)
172 {
173 ipc_entry_bits_t sum = (oldgen + IE_BITS_GEN_ONE) & IE_BITS_GEN_MASK;
174 ipc_entry_bits_t roll = oldgen & IE_BITS_ROLL_MASK;
175 ipc_entry_bits_t newgen = (sum % IE_BITS_ROLL(oldgen)) | roll;
176 return newgen;
177 }
178
179 /* Determine if a gencount has rolled over or not. */
180 static inline boolean_t
ipc_entry_gen_rolled(ipc_entry_bits_t oldgen,ipc_entry_bits_t newgen)181 ipc_entry_gen_rolled(
182 ipc_entry_bits_t oldgen,
183 ipc_entry_bits_t newgen)
184 {
185 return (oldgen & IE_BITS_GEN_MASK) > (newgen & IE_BITS_GEN_MASK);
186 }
187
188 #else
189 #define IE_BITS_GEN_MASK 0
190 #define IE_BITS_GEN(bits) 0
191 #define IE_BITS_GEN_ONE 0
192 #define IE_BITS_ROLL_POS 0
193 #define IE_BITS_ROLL_MASK 0
194 #define IE_BITS_ROLL(bits) (bits)
195
196 static inline ipc_entry_bits_t
ipc_entry_new_rollpoint(ipc_entry_bits_t rollbits)197 ipc_entry_new_rollpoint(
198 ipc_entry_bits_t rollbits)
199 {
200 return 0;
201 }
202
203 static inline ipc_entry_bits_t
ipc_entry_new_gen(ipc_entry_bits_t oldgen)204 ipc_entry_new_gen(
205 ipc_entry_bits_t oldgen)
206 {
207 return 0;
208 }
209
210 static inline boolean_t
ipc_entry_gen_rolled(ipc_entry_bits_t oldgen,ipc_entry_bits_t newgen)211 ipc_entry_gen_rolled(
212 ipc_entry_bits_t oldgen,
213 ipc_entry_bits_t newgen)
214 {
215 return FALSE;
216 }
217
218 #endif /* !USE_PORT_GEN */
219
220 #define IE_BITS_RIGHT_MASK 0x007fffff /* relevant to the right */
221 /*
222 * Exported interfaces
223 */
224
225 /* Search for entry in a space by name */
226 extern ipc_entry_t ipc_entry_lookup(
227 ipc_space_t space,
228 mach_port_name_t name);
229
230 /* Hold a number of entries in a locked space */
231 extern kern_return_t ipc_entries_hold(
232 ipc_space_t space,
233 natural_t count);
234
235 /* claim and initialize a held entry in a locked space */
236 extern kern_return_t ipc_entry_claim(
237 ipc_space_t space,
238 ipc_object_t object,
239 mach_port_name_t *namep,
240 ipc_entry_t *entryp);
241
242 /* Allocate an entry in a space, growing the space if necessary */
243 extern kern_return_t ipc_entry_alloc(
244 ipc_space_t space,
245 ipc_object_t object,
246 mach_port_name_t *namep,
247 ipc_entry_t *entryp);
248
249 /* Allocate/find an entry in a space with a specific name */
250 extern kern_return_t ipc_entry_alloc_name(
251 ipc_space_t space,
252 mach_port_name_t name,
253 ipc_entry_t *entryp);
254
255 /* Deallocate an entry from a space */
256 extern void ipc_entry_dealloc(
257 ipc_space_t space,
258 ipc_object_t object,
259 mach_port_name_t name,
260 ipc_entry_t entry);
261
262 /* Mark and entry modified in a space */
263 extern void ipc_entry_modified(
264 ipc_space_t space,
265 mach_port_name_t name,
266 ipc_entry_t entry);
267
268 /* Grow the table in a space */
269 extern kern_return_t ipc_entry_grow_table(
270 ipc_space_t space,
271 ipc_table_elems_t target_size);
272
273 /* mask on/off default entry generation bits */
274 extern mach_port_name_t ipc_entry_name_mask(
275 mach_port_name_t name);
276 #endif /* _IPC_IPC_ENTRY_H_ */
277