osfmk/kern/lock.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*
  26  * @OSF_COPYRIGHT@
  27  */
  28 /*
  29  * Mach Operating System
  30  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  31  * All Rights Reserved.
  32  *
  33  * Permission to use, copy, modify and distribute this software and its
  34  * documentation is hereby granted, provided that both the copyright
  35  * notice and this permission notice appear in all copies of the
  36  * software, derivative works or modified versions, and any portions
  37  * thereof, and that both notices appear in supporting documentation.
  38  *
  39  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  40  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  41  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  42  *
  43  * Carnegie Mellon requests users of this software to return to
  44  *
  45  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  46  *  School of Computer Science
  47  *  Carnegie Mellon University
  48  *  Pittsburgh PA 15213-3890
  49  *
  50  * any improvements or extensions that they make and grant Carnegie Mellon
  51  * the rights to redistribute these changes.
  52  */
  53 /*
  54  *      File:   kern/lock.h
  55  *      Author: Avadis Tevanian, Jr., Michael Wayne Young
  56  *      Date:   1985
  57  *
  58  *      Higher Level Locking primitives definitions
  59  */
  60
  61 #ifndef _KERN_LOCK_H_
  62 #define _KERN_LOCK_H_
  63
  64 /*
  65  * Configuration variables:
  66  *
  67  *
  68  *      MACH_LDEBUG:    record pc and thread of callers, turn on
  69  *                      all lock debugging.
  70  *
  71  *
  72  *      ETAP:           The Event Trace Analysis Package (ETAP) monitors
  73  *                      and records micro-kernel lock behavior and general
  74  *                      kernel events.  ETAP supports two levels of
  75  *                      tracing for locks:
  76  *                              - cumulative (ETAP_LOCK_ACCUMULATE)
  77  *                              - monitored  (ETAP_LOCK_MONITOR)
  78  *
  79  *                      Note: If either level of tracing is configured then
  80  *                            ETAP_LOCK_TRACE is automatically defined to
  81  *                            equal one.
  82  *
  83  *                      Several macros are added throughout the lock code to
  84  *                      allow for convenient configuration.
  85  */
  86
  87 #include <kern/simple_lock.h>
  88 #include <machine/lock.h>
  89 #include <mach/etap_events.h>
  90 #include <mach/etap.h>
  91
  92 /*
  93  *      The Mach lock package exports the following high-level
  94  *      lock abstractions:
  95  *
  96  *      Lock Type  Properties
  97  *      mutex      blocking mutual exclusion lock, intended for
  98  *                 SMP synchronization (vanishes on a uniprocessor);
  99  *                 supports debugging, statistics, and pre-emption
 100  *      lock       blocking synchronization permitting multiple
 101  *                 simultaneous readers or a single writer; supports
 102  *                 debugging and statistics but not pre-emption
 103  *
 104  *      In general, mutex locks are preferred over all others, as the
 105  *      mutex supports pre-emption and relinquishes the processor
 106  *      upon contention.
 107  *
 108  */
 109
 110 #include <sys/appleapiopts.h>
 111
 112 #ifdef  __APPLE_API_PRIVATE
 113
 114 #ifdef  MACH_KERNEL_PRIVATE
 115
 116 /*
 117  *      A simple mutex lock.
 118  *      Do not change the order of the fields in this structure without
 119  *      changing the machine-dependent assembler routines which depend
 120  *      on them.
 121  */
 122
 123 #include <mach_ldebug.h>
 124 #include <kern/etap_options.h>
 125 #include <kern/etap_pool.h>
 126
 127 typedef struct {
 128         hw_lock_data_t  interlock;
 129         hw_lock_data_t  locked;
 130         uint16_t                waiters;
 131         uint16_t                promoted_pri;
 132 #if     MACH_LDEBUG
 133         int             type;
 134 #define MUTEX_TAG       0x4d4d
 135         vm_offset_t     pc;
 136         vm_offset_t     thread;
 137 #endif  /* MACH_LDEBUG */
 138 #if     ETAP_LOCK_TRACE
 139         union {         /* Must be overlaid on the event_tablep */
 140             struct event_table_chain event_table_chain;
 141             struct {
 142                 event_table_t   event_tablep;     /* ptr to event table entry */
 143                 etap_time_t     start_hold_time;  /* Time of last acquistion */
 144             } s;
 145         } u;
 146 #endif  /* ETAP_LOCK_TRACE */
 147 #if     ETAP_LOCK_ACCUMULATE
 148         cbuff_entry_t   cbuff_entry;      /* cumulative buffer entry          */
 149 #endif  /* ETAP_LOCK_ACCUMULATE */
 150 #if     ETAP_LOCK_MONITOR
 151         vm_offset_t     start_pc;         /* pc where lock operation began    */
 152         vm_offset_t     end_pc;           /* pc where lock operation ended    */
 153 #endif  /* ETAP_LOCK_MONITOR */
 154 } mutex_t;
 155
 156 #define decl_mutex_data(class,name)     class mutex_t name;
 157 #define mutex_addr(m)                   (&(m))
 158
 159 extern void             mutex_init(
 160                                         mutex_t                 *mutex,
 161                                         etap_event_t    tag);
 162
 163 extern void             mutex_lock_wait(
 164                                         mutex_t                 *mutex,
 165                                         thread_t                holder);
 166
 167 extern int              mutex_lock_acquire(
 168                                         mutex_t                 *mutex);
 169
 170 extern void             mutex_unlock_wakeup(
 171                                         mutex_t                 *mutex,
 172                                         thread_t                holder);
 173
 174 extern boolean_t        mutex_preblock(
 175                                                 mutex_t                 *mutex,
 176                                                 thread_t                thread);
 177
 178 extern boolean_t        mutex_preblock_wait(
 179                                                 mutex_t                 *mutex,
 180                                                 thread_t                thread,
 181                                                 thread_t                holder);
 182
 183 extern void             interlock_unlock(
 184                                         hw_lock_t               lock);
 185
 186 #endif  /* MACH_KERNEL_PRIVATE */
 187
 188 extern void             mutex_pause(void);
 189
 190 #endif  /* __APPLE_API_PRIVATE */
 191
 192 #if             !defined(MACH_KERNEL_PRIVATE)
 193
 194 typedef struct __mutex__ mutex_t;
 195
 196 #endif  /* MACH_KERNEL_PRIVATE */
 197
 198 extern mutex_t  *mutex_alloc(
 199                                         etap_event_t    tag);
 200
 201 extern void             mutex_free(
 202                                         mutex_t                 *mutex);
 203
 204 extern void             mutex_lock(
 205                                         mutex_t                 *mutex);
 206
 207 extern void             mutex_unlock(
 208                                         mutex_t                 *mutex);
 209
 210 extern boolean_t        mutex_try(
 211                                                 mutex_t         *mutex);
 212
 213 #ifdef  __APPLE_API_PRIVATE
 214
 215 #ifdef MACH_KERNEL_PRIVATE
 216
 217 /*
 218  *      The general lock structure.  Provides for multiple readers,
 219  *      upgrading from read to write, and sleeping until the lock
 220  *      can be gained.
 221  *
 222  *      On some architectures, assembly language code in the 'inline'
 223  *      program fiddles the lock structures.  It must be changed in
 224  *      concert with the structure layout.
 225  *
 226  *      Only the "interlock" field is used for hardware exclusion;
 227  *      other fields are modified with normal instructions after
 228  *      acquiring the interlock bit.
 229  */
 230
 231 typedef struct {
 232         decl_simple_lock_data(,interlock) /* "hardware" interlock field */
 233         volatile unsigned int
 234                 read_count:16,  /* No. of accepted readers */
 235                 want_upgrade:1, /* Read-to-write upgrade waiting */
 236                 want_write:1,   /* Writer is waiting, or
 237                                    locked for write */
 238                 waiting:1,      /* Someone is sleeping on lock */
 239                 can_sleep:1;    /* Can attempts to lock go to sleep? */
 240 #if     ETAP_LOCK_TRACE
 241         union {         /* Must be overlaid on the event_tablep */
 242             struct event_table_chain event_table_chain;
 243             struct {
 244                 event_table_t event_tablep;     /* ptr to event table entry */
 245                 start_data_node_t start_list;   /* linked list of start times
 246                                                    and pcs */
 247             } s;
 248         } u;
 249 #endif  /* ETAP_LOCK_TRACE */
 250 #if     ETAP_LOCK_ACCUMULATE
 251         cbuff_entry_t   cbuff_write;    /* write cumulative buffer entry      */
 252         cbuff_entry_t   cbuff_read;     /* read  cumulative buffer entry      */
 253 #endif  /* ETAP_LOCK_ACCUMULATE */
 254 } lock_t;
 255
 256 /* Sleep locks must work even if no multiprocessing */
 257
 258 /*
 259  * Complex lock operations
 260  */
 261
 262 #if ETAP
 263 /*
 264  *      Locks have a pointer into an event_table entry that names the
 265  *      corresponding lock event and controls whether it is being traced.
 266  *      Initially this pointer is into a read-only table event_table_init[].
 267  *      Once dynamic allocation becomes possible a modifiable copy of the table
 268  *      is allocated and pointers are set to within this copy.  The pointers
 269  *      that were already in place at that point need to be switched to point
 270  *      into the copy.  To do this we overlay the event_table_chain structure
 271  *      onto sufficiently-big elements of the various lock structures so we
 272  *      can sweep down this list switching the pointers.  The assumption is
 273  *      that we will not want to enable tracing before this is done (which is
 274  *      after all during kernel bootstrap, before any user tasks are launched).
 275  *
 276  *      This is admittedly rather ugly but so were the alternatives:
 277  *      - record the event_table pointers in a statically-allocated array
 278  *        (dynamic allocation not yet being available) -- but there were
 279  *        over 8000 of them;
 280  *      - add a new link field to each lock structure;
 281  *      - change pointers to array indices -- this adds quite a bit of
 282  *        arithmetic to every lock operation that might be traced.
 283  */
 284 #define lock_event_table(lockp)         ((lockp)->u.s.event_tablep)
 285 #define lock_start_hold_time(lockp)     ((lockp)->u.s.start_hold_time)
 286 #endif  /* ETAP_LOCK_TRACE */
 287
 288 extern void     lock_init               (lock_t*,
 289                                          boolean_t,
 290                                          etap_event_t,
 291                                          etap_event_t);
 292
 293 #endif  /* MACH_KERNEL_PRIVATE */
 294
 295 extern unsigned int LockTimeOut;        /* Standard lock timeout value */
 296
 297 #endif  /* __APPLE_API_PRIVATE */
 298
 299 #if             !defined(MACH_KERNEL_PRIVATE)
 300
 301 typedef struct __lock__ lock_t;
 302 extern lock_t *lock_alloc(boolean_t, etap_event_t, etap_event_t);
 303 void lock_free(lock_t *);
 304
 305 #endif  /* MACH_KERNEL_PRIVATE */
 306
 307 extern void     lock_write              (lock_t*);
 308 extern void     lock_read               (lock_t*);
 309 extern void     lock_done               (lock_t*);
 310 extern void     lock_write_to_read      (lock_t*);
 311
 312 #define lock_read_done(l)               lock_done(l)
 313 #define lock_write_done(l)              lock_done(l)
 314
 315 extern boolean_t lock_read_to_write     (lock_t*);  /* vm_map is only user */
 316
 317 #endif  /* _KERN_LOCK_H_ */