include/urcu/arch/generic.h

   1 // SPDX-FileCopyrightText: 2010 Paolo Bonzini <pbonzini@redhat.com>
   2 //
   3 // SPDX-License-Identifier: LGPL-2.1-or-later
   4
   5 #ifndef _URCU_ARCH_GENERIC_H
   6 #define _URCU_ARCH_GENERIC_H
   7
   8 /*
   9  * arch_generic.h: common definitions for multiple architectures.
  10  */
  11
  12 #include <urcu/compiler.h>
  13 #include <urcu/config.h>
  14 #include <urcu/syscall-compat.h>
  15
  16 #ifdef __cplusplus
  17 extern "C" {
  18 #endif
  19
  20 #ifndef CAA_CACHE_LINE_SIZE
  21 #define CAA_CACHE_LINE_SIZE     64
  22 #endif
  23
  24 #if !defined(cmm_mc) && !defined(cmm_rmc) && !defined(cmm_wmc)
  25 #define CONFIG_HAVE_MEM_COHERENCY
  26 /*
  27  * Architectures with cache coherency must _not_ define cmm_mc/cmm_rmc/cmm_wmc.
  28  *
  29  * For them, cmm_mc/cmm_rmc/cmm_wmc are implemented with a simple
  30  * compiler barrier; in addition, we provide defaults for cmm_mb (using
  31  * GCC builtins) as well as cmm_rmb and cmm_wmb (defaulting to cmm_mb).
  32  */
  33
  34 #ifdef CONFIG_RCU_USE_ATOMIC_BUILTINS
  35
  36 # ifndef cmm_smp_mb
  37 #  define cmm_smp_mb() __atomic_thread_fence(__ATOMIC_SEQ_CST)
  38 # endif
  39
  40 #endif  /* CONFIG_RCU_USE_ATOMIC_BUILTINS */
  41
  42
  43 /*
  44  * cmm_mb() expands to __sync_synchronize() instead of __atomic_thread_fence
  45  * with SEQ_CST because the former "issues a full memory barrier" while the
  46  * latter "acts as a synchronization fence between threads" which is too weak
  47  * for what we want, for example with I/O devices.
  48  *
  49  * Even though sync_synchronize seems to be an alias for a sequential consistent
  50  * atomic thread fence on every architecture on GCC and Clang, this assumption
  51  * might be untrue in future.  Therefore, the definitions above are used to
  52  * ensure correct behavior in the future.
  53  *
  54  * The above defintions are quoted from the GCC manual.
  55  */
  56 #ifndef cmm_mb
  57 #define cmm_mb()    __sync_synchronize()
  58 #endif
  59
  60 #ifndef cmm_rmb
  61 #define cmm_rmb()       cmm_mb()
  62 #endif
  63
  64 #ifndef cmm_wmb
  65 #define cmm_wmb()       cmm_mb()
  66 #endif
  67
  68 #define cmm_mc()        cmm_barrier()
  69 #define cmm_rmc()       cmm_barrier()
  70 #define cmm_wmc()       cmm_barrier()
  71 #else
  72 /*
  73  * Architectures without cache coherency need something like the following:
  74  *
  75  * #define cmm_mc()     arch_cache_flush()
  76  * #define cmm_rmc()    arch_cache_flush_read()
  77  * #define cmm_wmc()    arch_cache_flush_write()
  78  *
  79  * Of these, only cmm_mc is mandatory. cmm_rmc and cmm_wmc default to
  80  * cmm_mc. cmm_mb/cmm_rmb/cmm_wmb use these definitions by default:
  81  *
  82  * #define cmm_mb()     cmm_mc()
  83  * #define cmm_rmb()    cmm_rmc()
  84  * #define cmm_wmb()    cmm_wmc()
  85  */
  86
  87 #ifndef cmm_mb
  88 #define cmm_mb()        cmm_mc()
  89 #endif
  90
  91 #ifndef cmm_rmb
  92 #define cmm_rmb()       cmm_rmc()
  93 #endif
  94
  95 #ifndef cmm_wmb
  96 #define cmm_wmb()       cmm_wmc()
  97 #endif
  98
  99 #ifndef cmm_rmc
 100 #define cmm_rmc()       cmm_mc()
 101 #endif
 102
 103 #ifndef cmm_wmc
 104 #define cmm_wmc()       cmm_mc()
 105 #endif
 106 #endif
 107
 108 /* Nop everywhere except on alpha. */
 109 #ifndef cmm_read_barrier_depends
 110 #define cmm_read_barrier_depends()
 111 #endif
 112
 113 #ifdef CONFIG_RCU_SMP
 114 #ifndef cmm_smp_mb
 115 #define cmm_smp_mb()    cmm_mb()
 116 #endif
 117 #ifndef cmm_smp_rmb
 118 #define cmm_smp_rmb()   cmm_rmb()
 119 #endif
 120 #ifndef cmm_smp_wmb
 121 #define cmm_smp_wmb()   cmm_wmb()
 122 #endif
 123 #ifndef cmm_smp_mc
 124 #define cmm_smp_mc()    cmm_mc()
 125 #endif
 126 #ifndef cmm_smp_rmc
 127 #define cmm_smp_rmc()   cmm_rmc()
 128 #endif
 129 #ifndef cmm_smp_wmc
 130 #define cmm_smp_wmc()   cmm_wmc()
 131 #endif
 132 #ifndef cmm_smp_read_barrier_depends
 133 #define cmm_smp_read_barrier_depends()  cmm_read_barrier_depends()
 134 #endif
 135 #else
 136 #ifndef cmm_smp_mb
 137 #define cmm_smp_mb()    cmm_barrier()
 138 #endif
 139 #ifndef cmm_smp_rmb
 140 #define cmm_smp_rmb()   cmm_barrier()
 141 #endif
 142 #ifndef cmm_smp_wmb
 143 #define cmm_smp_wmb()   cmm_barrier()
 144 #endif
 145 #ifndef cmm_smp_mc
 146 #define cmm_smp_mc()    cmm_barrier()
 147 #endif
 148 #ifndef cmm_smp_rmc
 149 #define cmm_smp_rmc()   cmm_barrier()
 150 #endif
 151 #ifndef cmm_smp_wmc
 152 #define cmm_smp_wmc()   cmm_barrier()
 153 #endif
 154 #ifndef cmm_smp_read_barrier_depends
 155 #define cmm_smp_read_barrier_depends()
 156 #endif
 157 #endif
 158
 159 #ifndef caa_cpu_relax
 160 #define caa_cpu_relax()         cmm_barrier()
 161 #endif
 162
 163 #ifndef HAS_CAA_GET_CYCLES
 164 #define HAS_CAA_GET_CYCLES
 165
 166 #if defined(__APPLE__)
 167
 168 #include <mach/mach.h>
 169 #include <mach/clock.h>
 170 #include <mach/mach_time.h>
 171 #include <time.h>
 172 #include <stdint.h>
 173
 174 typedef uint64_t caa_cycles_t;
 175
 176 static inline caa_cycles_t caa_get_cycles (void)
 177 {
 178         mach_timespec_t ts = { 0, 0 };
 179         static clock_serv_t clock_service;
 180
 181         if (caa_unlikely(!clock_service)) {
 182                 if (host_get_clock_service(mach_host_self(),
 183                                 SYSTEM_CLOCK, &clock_service))
 184                         return -1ULL;
 185         }
 186         if (caa_unlikely(clock_get_time(clock_service, &ts)))
 187                 return -1ULL;
 188         return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
 189 }
 190
 191 #elif defined(CONFIG_RCU_HAVE_CLOCK_GETTIME)
 192
 193 #include <time.h>
 194 #include <stdint.h>
 195
 196 typedef uint64_t caa_cycles_t;
 197
 198 static inline caa_cycles_t caa_get_cycles (void)
 199 {
 200         struct timespec ts;
 201
 202         if (caa_unlikely(clock_gettime(CLOCK_MONOTONIC, &ts)))
 203                 return -1ULL;
 204         return ((uint64_t) ts.tv_sec * 1000000000ULL) + ts.tv_nsec;
 205 }
 206
 207 #else
 208
 209 #error caa_get_cycles() not implemented for this platform.
 210
 211 #endif
 212
 213 #endif /* HAS_CAA_GET_CYCLES */
 214
 215 #ifdef __cplusplus
 216 }
 217 #endif
 218
 219 #endif /* _URCU_ARCH_GENERIC_H */