kern/synch_internal.h

   1 /*
   2  * Copyright (c) 2000-2013 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_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. Please obtain a copy of the License at
  10  * http://www.opensource.apple.com/apsl/ and read it before using this
  11  * file.
  12  *
  13  * The Original Code and all software distributed under the License are
  14  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  15  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  16  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  18  * Please see the License for the specific language governing rights and
  19  * limitations under the License.
  20  *
  21  * @APPLE_LICENSE_HEADER_END@
  22  */
  23
  24 #ifndef __SYNCH_INTERNAL_H__
  25 #define __SYNCH_INTERNAL_H__
  26
  27
  28 #define _PTHREAD_MTX_OPT_PSHARED 0x010
  29 #define _PTHREAD_MTX_OPT_NOTIFY 0x1000  /* notify to drop mutex handling in cvwait */
  30 #define _PTHREAD_MTX_OPT_MUTEX  0x2000 /* this is a mutex type  */
  31
  32
  33 #define PTHRW_COUNT_SHIFT       8
  34 #define PTHRW_INC               (1 << PTHRW_COUNT_SHIFT)
  35 #define PTHRW_BIT_MASK          ((1 << PTHRW_COUNT_SHIFT) - 1)
  36 #define PTHRW_COUNT_MASK        ((uint32_t)~PTHRW_BIT_MASK)
  37 #define PTHRW_MAX_READERS       PTHRW_COUNT_MASK
  38
  39 // L word
  40 #define PTH_RWL_KBIT            0x01    // cannot acquire in user mode
  41 #define PTH_RWL_EBIT            0x02    // exclusive lock in progress
  42 #define PTH_RWL_WBIT            0x04    // write waiters pending in kernel
  43 #define PTH_RWL_PBIT            0x04    // prepost (cv) pending in kernel
  44
  45 #define PTH_RWL_MTX_WAIT        0x20    // in cvar in mutex wait
  46 #define PTH_RWL_UBIT            0x40    // lock is unlocked (no readers or writers)
  47 #define PTH_RWL_MBIT            0x40    // overlapping grants from kernel (only in updateval)
  48 #define PTH_RWL_IBIT            0x80    // lock reset, held until first successful unlock
  49
  50 #define PTHRW_RWL_INIT          PTH_RWL_IBIT    // reset on the lock bits (U)
  51 #define PTHRW_RWLOCK_INIT       (PTH_RWL_IBIT | PTH_RWL_UBIT)   // reset on the lock bits (U)
  52
  53 // S word
  54 #define PTH_RWS_SBIT            0x01    // kernel transition seq not set yet
  55 #define PTH_RWS_IBIT            0x02    // Sequence is not set on return from kernel
  56
  57 #define PTH_RWS_CV_CBIT         PTH_RWS_SBIT    // kernel has cleared all info w.r.s.t CV
  58 #define PTH_RWS_CV_PBIT         PTH_RWS_IBIT    // kernel has prepost/fake structs only,no waiters
  59 #define PTH_RWS_CV_BITSALL      (PTH_RWS_CV_CBIT | PTH_RWS_CV_PBIT)
  60 #define PTH_RWS_CV_MBIT         PTH_RWL_MBIT    // to indicate prepost return from kernel
  61 #define PTH_RWS_CV_RESET_PBIT   ((uint32_t)~PTH_RWS_CV_PBIT)
  62
  63 #define PTH_RWS_WSVBIT          0x04    // save W bit
  64
  65 #define PTHRW_RWS_SAVEMASK      (PTH_RWS_WSVBIT)        // save bits mask
  66
  67 #define PTHRW_RWS_INIT          PTH_RWS_SBIT    // reset on the lock bits (U)
  68
  69 // rw_flags
  70 #define PTHRW_KERN_PROCESS_SHARED       0x10
  71 #define PTHRW_KERN_PROCESS_PRIVATE      0x20
  72
  73 #define PTHREAD_MTX_TID_SWITCHING (uint64_t)-1
  74
  75 // L word tests
  76 #define is_rwl_ebit_set(x) (((x) & PTH_RWL_EBIT) != 0)
  77 #define is_rwl_wbit_set(x) (((x) & PTH_RWL_WBIT) != 0)
  78 #define is_rwl_ebit_clear(x) (((x) & PTH_RWL_EBIT) == 0)
  79 #define is_rwl_readoverlap(x) (((x) & PTH_RWL_MBIT) != 0)
  80
  81 // S word tests
  82 #define is_rws_setseq(x) (((x) & PTH_RWS_SBIT))
  83 #define is_rws_setunlockinit(x) (((x) & PTH_RWS_IBIT))
  84
  85 static inline int
  86 is_seqlower(uint32_t x, uint32_t y)
  87 {
  88         x &= PTHRW_COUNT_MASK;
  89         y &= PTHRW_COUNT_MASK;
  90         if (x < y) {
  91                 return ((y - x) < (PTHRW_MAX_READERS / 2));
  92         } else {
  93                 return ((x - y) > (PTHRW_MAX_READERS / 2));
  94         }
  95 }
  96
  97 static inline int
  98 is_seqlower_eq(uint32_t x, uint32_t y)
  99 {
 100         if ((x & PTHRW_COUNT_MASK) == (y & PTHRW_COUNT_MASK)) {
 101                 return 1;
 102         } else {
 103                 return is_seqlower(x, y);
 104         }
 105 }
 106
 107 static inline int
 108 is_seqhigher(uint32_t x, uint32_t y)
 109 {
 110         x &= PTHRW_COUNT_MASK;
 111         y &= PTHRW_COUNT_MASK;
 112         if (x > y) {
 113                 return ((x - y) < (PTHRW_MAX_READERS / 2));
 114         } else {
 115                 return ((y - x) > (PTHRW_MAX_READERS / 2));
 116         }
 117 }
 118
 119 static inline int
 120 is_seqhigher_eq(uint32_t x, uint32_t y)
 121 {
 122         if ((x & PTHRW_COUNT_MASK) == (y & PTHRW_COUNT_MASK)) {
 123                 return 1;
 124         } else {
 125                 return is_seqhigher(x,y);
 126         }
 127 }
 128
 129 static inline int
 130 diff_genseq(uint32_t x, uint32_t y)
 131 {
 132         x &= PTHRW_COUNT_MASK;
 133         y &= PTHRW_COUNT_MASK;
 134         if (x == y) {
 135                 return 0;
 136         } else if (x > y)  {
 137                 return x - y;
 138         } else {
 139                 return ((PTHRW_MAX_READERS - y) + x + PTHRW_INC);
 140         }
 141 }
 142
 143 static inline int
 144 find_diff(uint32_t upto, uint32_t lowest)
 145 {
 146         uint32_t diff;
 147
 148         if (upto == lowest)
 149                 return(0);
 150 #if 0
 151         diff = diff_genseq(upto, lowest);
 152 #else
 153         if (is_seqlower(upto, lowest) != 0)
 154                 diff = diff_genseq(lowest, upto);
 155         else
 156                 diff = diff_genseq(upto, lowest);
 157 #endif
 158         diff = (diff >> PTHRW_COUNT_SHIFT);
 159         return(diff);
 160 }
 161
 162 #endif /* __SYNCH_INTERNAL_H__ */