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  * Copyright (C) 1998 Apple Computer
  24  * All Rights Reserved
  25  */
  26 /*
  27  * @OSF_COPYRIGHT@
  28  */
  29 /*
  30  * Mach Operating System
  31  * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
  32  * All Rights Reserved.
  33  *
  34  * Permission to use, copy, modify and distribute this software and its
  35  * documentation is hereby granted, provided that both the copyright
  36  * notice and this permission notice appear in all copies of the
  37  * software, derivative works or modified versions, and any portions
  38  * thereof, and that both notices appear in supporting documentation.
  39  *
  40  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  41  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  42  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  43  *
  44  * Carnegie Mellon requests users of this software to return to
  45  *
  46  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  47  *  School of Computer Science
  48  *  Carnegie Mellon University
  49  *  Pittsburgh PA 15213-3890
  50  *
  51  * any improvements or extensions that they make and grant Carnegie Mellon
  52  * the rights to redistribute these changes.
  53  */
  54 /*
  55  *      File:   kern/lock.h
  56  *      Author: Avadis Tevanian, Jr., Michael Wayne Young
  57  *      Date:   1985
  58  *
  59  *      Higher Level Locking primitives definitions
  60  */
  61
  62 #ifndef _KERN_LOCK_H_
  63 #define _KERN_LOCK_H_
  64
  65 /*
  66  * Configuration variables:
  67  *
  68  *
  69  *      MACH_LDEBUG:    record pc and thread of callers, turn on
  70  *                      all lock debugging.
  71  *
  72  *
  73  *      ETAP:           The Event Trace Analysis Package (ETAP) monitors
  74  *                      and records micro-kernel lock behavior and general
  75  *                      kernel events.  ETAP supports two levels of
  76  *                      tracing for locks:
  77  *                              - cumulative (ETAP_LOCK_ACCUMULATE)
  78  *                              - monitored  (ETAP_LOCK_MONITOR)
  79  *
  80  *                      Note: If either level of tracing is configured then
  81  *                            ETAP_LOCK_TRACE is automatically defined to
  82  *                            equal one.
  83  *
  84  *                      Several macros are added throughout the lock code to
  85  *                      allow for convenient configuration.
  86  */
  87
  88 #include <kern/simple_lock.h>
  89 #include <machine/lock.h>
  90 #include <mach/etap_events.h>
  91 #include <mach/etap.h>
  92
  93 /*
  94  *      The Mach lock package exports the following high-level
  95  *      lock abstractions:
  96  *
  97  *      Lock Type  Properties
  98  *      mutex      blocking mutual exclusion lock, intended for
  99  *                 SMP synchronization (vanishes on a uniprocessor);
 100  *                 supports debugging, statistics, and pre-emption
 101  *      lock       blocking synchronization permitting multiple
 102  *                 simultaneous readers or a single writer; supports
 103  *                 debugging and statistics but not pre-emption
 104  *
 105  *      In general, mutex locks are preferred over all others, as the
 106  *      mutex supports pre-emption and relinquishes the processor
 107  *      upon contention.
 108  *
 109  */
 110
 111 /*
 112  *      A simple mutex lock.
 113  *      Do not change the order of the fields in this structure without
 114  *      changing the machine-dependent assembler routines which depend
 115  *      on them.
 116  */
 117 #ifdef MACH_KERNEL_PRIVATE
 118 #include <mach_ldebug.h>
 119 #include <kern/etap_options.h>
 120 #include <kern/etap_pool.h>
 121
 122 typedef struct {
 123         hw_lock_data_t  interlock;
 124         hw_lock_data_t  locked;
 125         short           waiters;
 126 #if     MACH_LDEBUG
 127         int             type;
 128 #define MUTEX_TAG       0x4d4d
 129         vm_offset_t     pc;
 130         vm_offset_t     thread;
 131 #endif  /* MACH_LDEBUG */
 132 #if     ETAP_LOCK_TRACE
 133         union {         /* Must be overlaid on the event_tablep */
 134             struct event_table_chain event_table_chain;
 135             struct {
 136                 event_table_t   event_tablep;     /* ptr to event table entry */
 137                 etap_time_t     start_hold_time;  /* Time of last acquistion */
 138             } s;
 139         } u;
 140 #endif  /* ETAP_LOCK_TRACE */
 141 #if     ETAP_LOCK_ACCUMULATE
 142         cbuff_entry_t   cbuff_entry;      /* cumulative buffer entry          */
 143 #endif  /* ETAP_LOCK_ACCUMULATE */
 144 #if     ETAP_LOCK_MONITOR
 145         vm_offset_t     start_pc;         /* pc where lock operation began    */
 146         vm_offset_t     end_pc;           /* pc where lock operation ended    */
 147 #endif  /* ETAP_LOCK_MONITOR */
 148 } mutex_t;
 149
 150 #define decl_mutex_data(class,name)     class mutex_t name;
 151 #define mutex_addr(m)                   (&(m))
 152
 153 #if     MACH_LDEBUG
 154 #define mutex_held(m) (hw_lock_held(&((m)->locked)) && \
 155                        ((m)->thread == (int)current_thread()))
 156 #else   /* MACH_LDEBUG */
 157 #define mutex_held(m) hw_lock_held(&((m)->locked))
 158 #endif  /* MACH_LDEBUG */
 159
 160 #else /* MACH_KERNEL_PRIVATE */
 161
 162 typedef struct __mutex__ mutex_t;
 163 extern boolean_t mutex_held(mutex_t*);
 164
 165 #endif /* !MACH_KERNEL_PRIVATE */
 166
 167 extern mutex_t *mutex_alloc             (etap_event_t);
 168 extern void     mutex_free              (mutex_t*);
 169
 170 extern void     mutex_init              (mutex_t*, etap_event_t);
 171 extern void     _mutex_lock             (mutex_t*);
 172 extern void     mutex_unlock            (mutex_t*);
 173 extern boolean_t  _mutex_try            (mutex_t*);
 174
 175 extern void     mutex_lock_wait         (mutex_t*);
 176 extern void     mutex_unlock_wakeup     (mutex_t*);
 177 extern void     mutex_pause             (void);
 178 extern void     interlock_unlock        (hw_lock_t);
 179
 180 /*
 181  *      The general lock structure.  Provides for multiple readers,
 182  *      upgrading from read to write, and sleeping until the lock
 183  *      can be gained.
 184  *
 185  *      On some architectures, assembly language code in the 'inline'
 186  *      program fiddles the lock structures.  It must be changed in
 187  *      concert with the structure layout.
 188  *
 189  *      Only the "interlock" field is used for hardware exclusion;
 190  *      other fields are modified with normal instructions after
 191  *      acquiring the interlock bit.
 192  */
 193 #ifdef MACH_KERNEL_PRIVATE
 194 typedef struct {
 195         decl_simple_lock_data(,interlock) /* "hardware" interlock field */
 196         volatile unsigned int
 197                 read_count:16,  /* No. of accepted readers */
 198                 want_upgrade:1, /* Read-to-write upgrade waiting */
 199                 want_write:1,   /* Writer is waiting, or
 200                                    locked for write */
 201                 waiting:1,      /* Someone is sleeping on lock */
 202                 can_sleep:1;    /* Can attempts to lock go to sleep? */
 203 #if     ETAP_LOCK_TRACE
 204         union {         /* Must be overlaid on the event_tablep */
 205             struct event_table_chain event_table_chain;
 206             struct {
 207                 event_table_t event_tablep;     /* ptr to event table entry */
 208                 start_data_node_t start_list;   /* linked list of start times
 209                                                    and pcs */
 210             } s;
 211         } u;
 212 #endif  /* ETAP_LOCK_TRACE */
 213 #if     ETAP_LOCK_ACCUMULATE
 214         cbuff_entry_t   cbuff_write;    /* write cumulative buffer entry      */
 215         cbuff_entry_t   cbuff_read;     /* read  cumulative buffer entry      */
 216 #endif  /* ETAP_LOCK_ACCUMULATE */
 217 } lock_t;
 218
 219 /* Sleep locks must work even if no multiprocessing */
 220
 221 /*
 222  * Complex lock operations
 223  */
 224
 225 #if ETAP
 226 /*
 227  *      Locks have a pointer into an event_table entry that names the
 228  *      corresponding lock event and controls whether it is being traced.
 229  *      Initially this pointer is into a read-only table event_table_init[].
 230  *      Once dynamic allocation becomes possible a modifiable copy of the table
 231  *      is allocated and pointers are set to within this copy.  The pointers
 232  *      that were already in place at that point need to be switched to point
 233  *      into the copy.  To do this we overlay the event_table_chain structure
 234  *      onto sufficiently-big elements of the various lock structures so we
 235  *      can sweep down this list switching the pointers.  The assumption is
 236  *      that we will not want to enable tracing before this is done (which is
 237  *      after all during kernel bootstrap, before any user tasks are launched).
 238  *
 239  *      This is admittedly rather ugly but so were the alternatives:
 240  *      - record the event_table pointers in a statically-allocated array
 241  *        (dynamic allocation not yet being available) -- but there were
 242  *        over 8000 of them;
 243  *      - add a new link field to each lock structure;
 244  *      - change pointers to array indices -- this adds quite a bit of
 245  *        arithmetic to every lock operation that might be traced.
 246  */
 247 #define lock_event_table(lockp)         ((lockp)->u.s.event_tablep)
 248 #define lock_start_hold_time(lockp)     ((lockp)->u.s.start_hold_time)
 249 #endif  /* ETAP_LOCK_TRACE */
 250
 251 extern void     lock_init               (lock_t*,
 252                                          boolean_t,
 253                                          etap_event_t,
 254                                          etap_event_t);
 255
 256 #else /* MACH_KERNEL_PRIVATE */
 257
 258 typedef struct __lock__ lock_t;
 259 extern lock_t *lock_alloc(boolean_t, etap_event_t, etap_event_t);
 260 void lock_free(lock_t *);
 261
 262 #endif /* !MACH_KERNEL_PRIVATE */
 263
 264 extern void     lock_write              (lock_t*);
 265 extern void     lock_read               (lock_t*);
 266 extern void     lock_done               (lock_t*);
 267 extern void     lock_write_to_read      (lock_t*);
 268
 269 #define lock_read_done(l)               lock_done(l)
 270 #define lock_write_done(l)              lock_done(l)
 271
 272 extern boolean_t lock_read_to_write     (lock_t*);  /* vm_map is only user */
 273 extern unsigned int LockTimeOut;                                /* Standard lock timeout value */
 274
 275 #endif  /* _KERN_LOCK_H_ */