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
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   8  * Version 2.0 (the 'License'). You may not use this file except in
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  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
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  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  *
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  23  * Please see the License for the specific language governing rights and
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  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  *
  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 #define IPC_ENTRY_INDEX_BITS  20
 104 #define IPC_ENTRY_INDEX_MAX   ((1 << IPC_ENTRY_INDEX_BITS) - 1)
 105
 106 struct ipc_entry {
 107         struct ipc_object  *ie_object;
 108         ipc_entry_bits_t    ie_bits;
 109         uint32_t            ie_dist  : IPC_ENTRY_DIST_BITS;
 110         mach_port_index_t   ie_index : IPC_ENTRY_INDEX_BITS;
 111         union {
 112                 mach_port_index_t next;         /* next in freelist, or...  */
 113                 ipc_table_index_t request;      /* dead name request notify */
 114         } index;
 115 };
 116
 117 #define ie_request      index.request
 118 #define ie_next         index.next
 119
 120 #define IE_REQ_NONE             0               /* no request */
 121
 122 #define IE_BITS_UREFS_MASK      0x0000ffff      /* 16 bits of user-reference */
 123 #define IE_BITS_UREFS(bits)     ((bits) & IE_BITS_UREFS_MASK)
 124
 125 #define IE_BITS_TYPE_MASK       0x001f0000      /* 5 bits of capability type */
 126 #define IE_BITS_TYPE(bits)      ((bits) & IE_BITS_TYPE_MASK)
 127
 128 #ifndef NO_PORT_GEN
 129 #define IE_BITS_GEN_MASK        0xff000000      /* 8 bits for generation */
 130 #define IE_BITS_GEN(bits)       ((bits) & IE_BITS_GEN_MASK)
 131 #define IE_BITS_GEN_ONE         0x04000000      /* low bit of generation */
 132 #define IE_BITS_ROLL_POS        22              /* LSB pos of generation rollover */
 133 #define IE_BITS_ROLL_BITS       2               /* number of generation rollover bits */
 134 #define IE_BITS_ROLL_MASK       (((1 << IE_BITS_ROLL_BITS) - 1) << IE_BITS_ROLL_POS)
 135 #define IE_BITS_ROLL(bits)      ((((bits) & IE_BITS_ROLL_MASK) << 8) ^ IE_BITS_GEN_MASK)
 136
 137 /*
 138  * Restart a generation counter with the specified bits for the rollover point.
 139  * There are 4 different rollover points:
 140  * bits    rollover period
 141  * 0 0     64
 142  * 0 1     48
 143  * 1 0     32
 144  * 1 1     16
 145  */
 146 static inline ipc_entry_bits_t
 147 ipc_entry_new_rollpoint(
 148         ipc_entry_bits_t rollbits)
 149 {
 150         rollbits = (rollbits << IE_BITS_ROLL_POS) & IE_BITS_ROLL_MASK;
 151         ipc_entry_bits_t newgen = IE_BITS_GEN_MASK + IE_BITS_GEN_ONE;
 152         return newgen | rollbits;
 153 }
 154
 155 /*
 156  * Get the next gencount, modulo the entry's rollover point. If the sum rolls over,
 157  * the caller should re-start the generation counter with a different rollpoint.
 158  */
 159 static inline ipc_entry_bits_t
 160 ipc_entry_new_gen(
 161         ipc_entry_bits_t oldgen)
 162 {
 163         ipc_entry_bits_t sum  = (oldgen + IE_BITS_GEN_ONE) & IE_BITS_GEN_MASK;
 164         ipc_entry_bits_t roll = oldgen & IE_BITS_ROLL_MASK;
 165         ipc_entry_bits_t newgen = (sum % IE_BITS_ROLL(oldgen)) | roll;
 166         return newgen;
 167 }
 168
 169 /* Determine if a gencount has rolled over or not. */
 170 static inline boolean_t
 171 ipc_entry_gen_rolled(
 172         ipc_entry_bits_t oldgen,
 173         ipc_entry_bits_t newgen)
 174 {
 175         return (oldgen & IE_BITS_GEN_MASK) > (newgen & IE_BITS_GEN_MASK);
 176 }
 177
 178 #else
 179 #define IE_BITS_GEN_MASK        0
 180 #define IE_BITS_GEN(bits)       0
 181 #define IE_BITS_GEN_ONE         0
 182 #define IE_BITS_ROLL_POS        0
 183 #define IE_BITS_ROLL_MASK       0
 184 #define IE_BITS_ROLL(bits)      (bits)
 185
 186 static inline ipc_entry_bits_t
 187 ipc_entry_new_rollpoint(
 188         ipc_entry_bits_t rollbits)
 189 {
 190         return 0;
 191 }
 192
 193 static inline ipc_entry_bits_t
 194 ipc_entry_new_gen(
 195         ipc_entry_bits_t oldgen)
 196 {
 197         return 0;
 198 }
 199
 200 static inline boolean_t
 201 ipc_entry_gen_rolled(
 202         ipc_entry_bits_t oldgen,
 203         ipc_entry_bits_t newgen)
 204 {
 205         return FALSE;
 206 }
 207
 208 #endif  /* !USE_PORT_GEN */
 209
 210 #define IE_BITS_RIGHT_MASK      0x007fffff      /* relevant to the right */
 211 /*
 212  * Exported interfaces
 213  */
 214
 215 /* Search for entry in a space by name */
 216 extern ipc_entry_t ipc_entry_lookup(
 217         ipc_space_t             space,
 218         mach_port_name_t        name);
 219
 220 /* Hold a number of entries in a locked space */
 221 extern kern_return_t ipc_entries_hold(
 222         ipc_space_t             space,
 223         natural_t               count);
 224
 225 /* claim and initialize a held entry in a locked space */
 226 extern kern_return_t ipc_entry_claim(
 227         ipc_space_t             space,
 228         mach_port_name_t        *namep,
 229         ipc_entry_t             *entryp);
 230
 231 /* Allocate an entry in a space */
 232 extern kern_return_t ipc_entry_get(
 233         ipc_space_t             space,
 234         mach_port_name_t        *namep,
 235         ipc_entry_t             *entryp);
 236
 237 /* Allocate an entry in a space, growing the space if necessary */
 238 extern kern_return_t ipc_entry_alloc(
 239         ipc_space_t             space,
 240         mach_port_name_t        *namep,
 241         ipc_entry_t             *entryp);
 242
 243 /* Allocate/find an entry in a space with a specific name */
 244 extern kern_return_t ipc_entry_alloc_name(
 245         ipc_space_t             space,
 246         mach_port_name_t        name,
 247         ipc_entry_t             *entryp);
 248
 249 /* Deallocate an entry from a space */
 250 extern void ipc_entry_dealloc(
 251         ipc_space_t             space,
 252         mach_port_name_t        name,
 253         ipc_entry_t             entry);
 254
 255 /* Mark and entry modified in a space */
 256 extern void ipc_entry_modified(
 257         ipc_space_t             space,
 258         mach_port_name_t        name,
 259         ipc_entry_t             entry);
 260
 261 /* Grow the table in a space */
 262 extern kern_return_t ipc_entry_grow_table(
 263         ipc_space_t             space,
 264         ipc_table_elems_t       target_size);
 265
 266 /* mask on/off default entry generation bits */
 267 extern mach_port_name_t ipc_entry_name_mask(
 268         mach_port_name_t name);
 269 #endif  /* _IPC_IPC_ENTRY_H_ */