osfmk/ipc/ipc_entry.h

   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  Software.Distribution@CS.CMU.EDU
  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  *      This hash table converts (space, object) -> name.
  87  *      It is used independently of the other fields.
  88  *
  89  *      Free (unallocated) entries in the table have null ie_object
  90  *      fields.  The ie_bits field is zero except for IE_BITS_GEN.
  91  *      The ie_next (ie_request) field links free entries into a free list.
  92  *
  93  *      The first entry in the table (index 0) is always free.
  94  *      It is used as the head of the free list.
  95  */
  96
  97 struct ipc_entry {
  98         struct ipc_object *ie_object;
  99         ipc_entry_bits_t ie_bits;
 100         mach_port_index_t ie_index;
 101         union {
 102                 mach_port_index_t next;         /* next in freelist, or...  */
 103                 ipc_table_index_t request;      /* dead name request notify */
 104         } index;
 105 };
 106
 107 #define ie_request      index.request
 108 #define ie_next         index.next
 109
 110 #define IE_REQ_NONE             0               /* no request */
 111
 112 #define IE_BITS_UREFS_MASK      0x0000ffff      /* 16 bits of user-reference */
 113 #define IE_BITS_UREFS(bits)     ((bits) & IE_BITS_UREFS_MASK)
 114
 115 #define IE_BITS_TYPE_MASK       0x001f0000      /* 5 bits of capability type */
 116 #define IE_BITS_TYPE(bits)      ((bits) & IE_BITS_TYPE_MASK)
 117
 118 #ifndef NO_PORT_GEN
 119 #define IE_BITS_GEN_MASK        0xff000000      /* 8 bits for generation */
 120 #define IE_BITS_GEN(bits)       ((bits) & IE_BITS_GEN_MASK)
 121 #define IE_BITS_GEN_ONE         0x04000000      /* low bit of generation */
 122 #define IE_BITS_ROLL_POS        22              /* LSB pos of generation rollover */
 123 #define IE_BITS_ROLL_BITS       2               /* number of generation rollover bits */
 124 #define IE_BITS_ROLL_MASK       (((1 << IE_BITS_ROLL_BITS) - 1) << IE_BITS_ROLL_POS)
 125 #define IE_BITS_ROLL(bits)      ((((bits) & IE_BITS_ROLL_MASK) << 8) ^ IE_BITS_GEN_MASK)
 126
 127 /*
 128  * Restart a generation counter with the specified bits for the rollover point.
 129  * There are 4 different rollover points:
 130  * bits    rollover period
 131  * 0 0     64
 132  * 0 1     48
 133  * 1 0     32
 134  * 1 1     16
 135  */
 136 static inline ipc_entry_bits_t ipc_entry_new_rollpoint(
 137         ipc_entry_bits_t rollbits)
 138 {
 139         rollbits = (rollbits << IE_BITS_ROLL_POS) & IE_BITS_ROLL_MASK;
 140         ipc_entry_bits_t newgen = IE_BITS_GEN_MASK + IE_BITS_GEN_ONE;
 141         return (newgen | rollbits);
 142 }
 143
 144 /*
 145  * Get the next gencount, modulo the entry's rollover point. If the sum rolls over,
 146  * the caller should re-start the generation counter with a different rollpoint.
 147  */
 148 static inline ipc_entry_bits_t ipc_entry_new_gen(
 149         ipc_entry_bits_t oldgen)
 150 {
 151         ipc_entry_bits_t sum  = (oldgen + IE_BITS_GEN_ONE) & IE_BITS_GEN_MASK;
 152         ipc_entry_bits_t roll = oldgen & IE_BITS_ROLL_MASK;
 153         ipc_entry_bits_t newgen = (sum % IE_BITS_ROLL(oldgen)) | roll;
 154         return newgen;
 155 }
 156
 157 /* Determine if a gencount has rolled over or not. */
 158 static inline boolean_t ipc_entry_gen_rolled(
 159         ipc_entry_bits_t oldgen,
 160         ipc_entry_bits_t newgen)
 161 {
 162         return (oldgen & IE_BITS_GEN_MASK) > (newgen & IE_BITS_GEN_MASK);
 163 }
 164
 165 #else
 166 #define IE_BITS_GEN_MASK        0
 167 #define IE_BITS_GEN(bits)       0
 168 #define IE_BITS_GEN_ONE         0
 169 #define IE_BITS_ROLL_POS        0
 170 #define IE_BITS_ROLL_MASK       0
 171 #define IE_BITS_ROLL(bits)      (bits)
 172
 173 static inline ipc_entry_bits_t ipc_entry_new_rollpoint(
 174         ipc_entry_bits_t rollbits)
 175 {
 176         return 0;
 177 }
 178
 179 static inline ipc_entry_bits_t ipc_entry_new_gen(
 180         ipc_entry_bits_t oldgen)
 181 {
 182         return 0;
 183 }
 184
 185 static inline boolean_t ipc_entry_gen_rolled(
 186         ipc_entry_bits_t oldgen,
 187         ipc_entry_bits_t newgen)
 188 {
 189         return FALSE;
 190 }
 191
 192 #endif  /* !USE_PORT_GEN */
 193
 194 #define IE_BITS_RIGHT_MASK      0x007fffff      /* relevant to the right */
 195 /*
 196  * Exported interfaces
 197  */
 198
 199 /* Search for entry in a space by name */
 200 extern ipc_entry_t ipc_entry_lookup(
 201         ipc_space_t             space,
 202         mach_port_name_t        name);
 203
 204 /* Hold a number of entries in a locked space */
 205 extern kern_return_t ipc_entries_hold(
 206         ipc_space_t             space,
 207         natural_t               count);
 208
 209 /* claim and initialize a held entry in a locked space */
 210 extern kern_return_t ipc_entry_claim(
 211         ipc_space_t             space,
 212         mach_port_name_t        *namep,
 213         ipc_entry_t             *entryp);
 214
 215 /* Allocate an entry in a space */
 216 extern kern_return_t ipc_entry_get(
 217         ipc_space_t             space,
 218         mach_port_name_t        *namep,
 219         ipc_entry_t             *entryp);
 220
 221 /* Allocate an entry in a space, growing the space if necessary */
 222 extern kern_return_t ipc_entry_alloc(
 223         ipc_space_t             space,
 224         mach_port_name_t        *namep,
 225         ipc_entry_t             *entryp);
 226
 227 /* Allocate/find an entry in a space with a specific name */
 228 extern kern_return_t ipc_entry_alloc_name(
 229         ipc_space_t             space,
 230         mach_port_name_t        name,
 231         ipc_entry_t             *entryp);
 232
 233 /* Deallocate an entry from a space */
 234 extern void ipc_entry_dealloc(
 235         ipc_space_t             space,
 236         mach_port_name_t        name,
 237         ipc_entry_t             entry);
 238
 239 /* Mark and entry modified in a space */
 240 extern void ipc_entry_modified(
 241         ipc_space_t             space,
 242         mach_port_name_t        name,
 243         ipc_entry_t             entry);
 244
 245 /* Grow the table in a space */
 246 extern kern_return_t ipc_entry_grow_table(
 247         ipc_space_t             space,
 248         ipc_table_elems_t       target_size);
 249
 250 /* mask on/off default entry generation bits */
 251 extern mach_port_name_t ipc_entry_name_mask(
 252         mach_port_name_t name);
 253 #endif  /* _IPC_IPC_ENTRY_H_ */