osfmk/kern/lock.h

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /*
  23  * @OSF_COPYRIGHT@
  24  */
  25 /*
  26  * Mach Operating System
  27  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  28  * All Rights Reserved.
  29  *
  30  * Permission to use, copy, modify and distribute this software and its
  31  * documentation is hereby granted, provided that both the copyright
  32  * notice and this permission notice appear in all copies of the
  33  * software, derivative works or modified versions, and any portions
  34  * thereof, and that both notices appear in supporting documentation.
  35  *
  36  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  37  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  38  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  39  *
  40  * Carnegie Mellon requests users of this software to return to
  41  *
  42  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  43  *  School of Computer Science
  44  *  Carnegie Mellon University
  45  *  Pittsburgh PA 15213-3890
  46  *
  47  * any improvements or extensions that they make and grant Carnegie Mellon
  48  * the rights to redistribute these changes.
  49  */
  50 /*
  51  *      File:   kern/lock.h
  52  *      Author: Avadis Tevanian, Jr., Michael Wayne Young
  53  *      Date:   1985
  54  *
  55  *      Higher Level Locking primitives definitions
  56  */
  57
  58 #ifndef _KERN_LOCK_H_
  59 #define _KERN_LOCK_H_
  60
  61 /*
  62  * Configuration variables:
  63  *
  64  *
  65  *      MACH_LDEBUG:    record pc and thread of callers, turn on
  66  *                      all lock debugging.
  67  *
  68  *
  69  *      ETAP:           The Event Trace Analysis Package (ETAP) monitors
  70  *                      and records micro-kernel lock behavior and general
  71  *                      kernel events.  ETAP supports two levels of
  72  *                      tracing for locks:
  73  *                              - cumulative (ETAP_LOCK_ACCUMULATE)
  74  *                              - monitored  (ETAP_LOCK_MONITOR)
  75  *
  76  *                      Note: If either level of tracing is configured then
  77  *                            ETAP_LOCK_TRACE is automatically defined to
  78  *                            equal one.
  79  *
  80  *                      Several macros are added throughout the lock code to
  81  *                      allow for convenient configuration.
  82  */
  83
  84 #include <kern/simple_lock.h>
  85 #include <machine/lock.h>
  86 #include <mach/etap_events.h>
  87 #include <mach/etap.h>
  88
  89 /*
  90  *      The Mach lock package exports the following high-level
  91  *      lock abstractions:
  92  *
  93  *      Lock Type  Properties
  94  *      mutex      blocking mutual exclusion lock, intended for
  95  *                 SMP synchronization (vanishes on a uniprocessor);
  96  *                 supports debugging, statistics, and pre-emption
  97  *      lock       blocking synchronization permitting multiple
  98  *                 simultaneous readers or a single writer; supports
  99  *                 debugging and statistics but not pre-emption
 100  *
 101  *      In general, mutex locks are preferred over all others, as the
 102  *      mutex supports pre-emption and relinquishes the processor
 103  *      upon contention.
 104  *
 105  */
 106
 107 #include <sys/appleapiopts.h>
 108
 109 #ifdef  __APPLE_API_PRIVATE
 110
 111 #ifdef  MACH_KERNEL_PRIVATE
 112
 113 /*
 114  *      A simple mutex lock.
 115  *      Do not change the order of the fields in this structure without
 116  *      changing the machine-dependent assembler routines which depend
 117  *      on them.
 118  */
 119
 120 #include <mach_ldebug.h>
 121 #include <kern/etap_options.h>
 122 #include <kern/etap_pool.h>
 123
 124 typedef struct {
 125         hw_lock_data_t  interlock;
 126         hw_lock_data_t  locked;
 127         uint16_t                waiters;
 128         uint16_t                promoted_pri;
 129 #if     MACH_LDEBUG
 130         int             type;
 131 #define MUTEX_TAG       0x4d4d
 132         vm_offset_t     pc;
 133         vm_offset_t     thread;
 134 #endif  /* MACH_LDEBUG */
 135 #if     ETAP_LOCK_TRACE
 136         union {         /* Must be overlaid on the event_tablep */
 137             struct event_table_chain event_table_chain;
 138             struct {
 139                 event_table_t   event_tablep;     /* ptr to event table entry */
 140                 etap_time_t     start_hold_time;  /* Time of last acquistion */
 141             } s;
 142         } u;
 143 #endif  /* ETAP_LOCK_TRACE */
 144 #if     ETAP_LOCK_ACCUMULATE
 145         cbuff_entry_t   cbuff_entry;      /* cumulative buffer entry          */
 146 #endif  /* ETAP_LOCK_ACCUMULATE */
 147 #if     ETAP_LOCK_MONITOR
 148         vm_offset_t     start_pc;         /* pc where lock operation began    */
 149         vm_offset_t     end_pc;           /* pc where lock operation ended    */
 150 #endif  /* ETAP_LOCK_MONITOR */
 151 } mutex_t;
 152
 153 #define decl_mutex_data(class,name)     class mutex_t name;
 154 #define mutex_addr(m)                   (&(m))
 155
 156 extern void     mutex_init              (mutex_t*, etap_event_t);
 157 extern void     mutex_lock_wait         (mutex_t *, thread_act_t);
 158 extern int      mutex_lock_acquire      (mutex_t *);
 159 extern void     mutex_unlock_wakeup     (mutex_t*, thread_act_t);
 160 extern void     interlock_unlock        (hw_lock_t);
 161
 162 #endif  /* MACH_KERNEL_PRIVATE */
 163
 164 extern void     mutex_pause             (void);
 165
 166 #endif  /* __APPLE_API_PRIVATE */
 167
 168 #if             !defined(MACH_KERNEL_PRIVATE)
 169
 170 typedef struct __mutex__ mutex_t;
 171
 172 #endif  /* MACH_KERNEL_PRIVATE */
 173
 174 extern mutex_t *mutex_alloc             (etap_event_t);
 175 extern void     mutex_free              (mutex_t*);
 176 extern void     mutex_lock              (mutex_t*);
 177 extern void     mutex_unlock            (mutex_t*);
 178 extern boolean_t mutex_try              (mutex_t*);
 179
 180 #ifdef  __APPLE_API_PRIVATE
 181
 182 #ifdef MACH_KERNEL_PRIVATE
 183
 184 /*
 185  *      The general lock structure.  Provides for multiple readers,
 186  *      upgrading from read to write, and sleeping until the lock
 187  *      can be gained.
 188  *
 189  *      On some architectures, assembly language code in the 'inline'
 190  *      program fiddles the lock structures.  It must be changed in
 191  *      concert with the structure layout.
 192  *
 193  *      Only the "interlock" field is used for hardware exclusion;
 194  *      other fields are modified with normal instructions after
 195  *      acquiring the interlock bit.
 196  */
 197
 198 typedef struct {
 199         decl_simple_lock_data(,interlock) /* "hardware" interlock field */
 200         volatile unsigned int
 201                 read_count:16,  /* No. of accepted readers */
 202                 want_upgrade:1, /* Read-to-write upgrade waiting */
 203                 want_write:1,   /* Writer is waiting, or
 204                                    locked for write */
 205                 waiting:1,      /* Someone is sleeping on lock */
 206                 can_sleep:1;    /* Can attempts to lock go to sleep? */
 207 #if     ETAP_LOCK_TRACE
 208         union {         /* Must be overlaid on the event_tablep */
 209             struct event_table_chain event_table_chain;
 210             struct {
 211                 event_table_t event_tablep;     /* ptr to event table entry */
 212                 start_data_node_t start_list;   /* linked list of start times
 213                                                    and pcs */
 214             } s;
 215         } u;
 216 #endif  /* ETAP_LOCK_TRACE */
 217 #if     ETAP_LOCK_ACCUMULATE
 218         cbuff_entry_t   cbuff_write;    /* write cumulative buffer entry      */
 219         cbuff_entry_t   cbuff_read;     /* read  cumulative buffer entry      */
 220 #endif  /* ETAP_LOCK_ACCUMULATE */
 221 } lock_t;
 222
 223 /* Sleep locks must work even if no multiprocessing */
 224
 225 /*
 226  * Complex lock operations
 227  */
 228
 229 #if ETAP
 230 /*
 231  *      Locks have a pointer into an event_table entry that names the
 232  *      corresponding lock event and controls whether it is being traced.
 233  *      Initially this pointer is into a read-only table event_table_init[].
 234  *      Once dynamic allocation becomes possible a modifiable copy of the table
 235  *      is allocated and pointers are set to within this copy.  The pointers
 236  *      that were already in place at that point need to be switched to point
 237  *      into the copy.  To do this we overlay the event_table_chain structure
 238  *      onto sufficiently-big elements of the various lock structures so we
 239  *      can sweep down this list switching the pointers.  The assumption is
 240  *      that we will not want to enable tracing before this is done (which is
 241  *      after all during kernel bootstrap, before any user tasks are launched).
 242  *
 243  *      This is admittedly rather ugly but so were the alternatives:
 244  *      - record the event_table pointers in a statically-allocated array
 245  *        (dynamic allocation not yet being available) -- but there were
 246  *        over 8000 of them;
 247  *      - add a new link field to each lock structure;
 248  *      - change pointers to array indices -- this adds quite a bit of
 249  *        arithmetic to every lock operation that might be traced.
 250  */
 251 #define lock_event_table(lockp)         ((lockp)->u.s.event_tablep)
 252 #define lock_start_hold_time(lockp)     ((lockp)->u.s.start_hold_time)
 253 #endif  /* ETAP_LOCK_TRACE */
 254
 255 extern void     lock_init               (lock_t*,
 256                                          boolean_t,
 257                                          etap_event_t,
 258                                          etap_event_t);
 259
 260 #endif  /* MACH_KERNEL_PRIVATE */
 261
 262 extern unsigned int LockTimeOut;        /* Standard lock timeout value */
 263
 264 #endif  /* __APPLE_API_PRIVATE */
 265
 266 #if             !defined(MACH_KERNEL_PRIVATE)
 267
 268 typedef struct __lock__ lock_t;
 269 extern lock_t *lock_alloc(boolean_t, etap_event_t, etap_event_t);
 270 void lock_free(lock_t *);
 271
 272 #endif  /* MACH_KERNEL_PRIVATE */
 273
 274 extern void     lock_write              (lock_t*);
 275 extern void     lock_read               (lock_t*);
 276 extern void     lock_done               (lock_t*);
 277 extern void     lock_write_to_read      (lock_t*);
 278
 279 #define lock_read_done(l)               lock_done(l)
 280 #define lock_write_done(l)              lock_done(l)
 281
 282 extern boolean_t lock_read_to_write     (lock_t*);  /* vm_map is only user */
 283
 284 #endif  /* _KERN_LOCK_H_ */