include/urcu/system.h

   1 // SPDX-FileCopyrightText: 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   2 //
   3 // SPDX-License-Identifier: MIT
   4
   5 #ifndef _URCU_SYSTEM_H
   6 #define _URCU_SYSTEM_H
   7
   8 /*
   9  * System definitions.
  10  */
  11
  12 #include <urcu/config.h>
  13 #include <urcu/compiler.h>
  14 #include <urcu/arch.h>
  15
  16 #ifdef CONFIG_RCU_USE_ATOMIC_BUILTINS
  17
  18 #define CMM_LOAD_SHARED(x)                                              \
  19         __atomic_load_n(cmm_cast_volatile(&(x)), __ATOMIC_RELAXED)
  20
  21 #define _CMM_LOAD_SHARED(x) CMM_LOAD_SHARED(x)
  22
  23 #define CMM_STORE_SHARED(x, v)                                  \
  24         __extension__                                           \
  25         ({                                                      \
  26                 __typeof__(v) _v = (v);                         \
  27                 __atomic_store_n(cmm_cast_volatile(&(x)), _v,   \
  28                                  __ATOMIC_RELAXED);             \
  29                 _v;                                             \
  30         })
  31
  32 #define _CMM_STORE_SHARED(x, v) CMM_STORE_SHARED(x, v)
  33
  34 #else
  35 /*
  36  * Identify a shared load. A cmm_smp_rmc() or cmm_smp_mc() should come
  37  * before the load.
  38  */
  39 #define _CMM_LOAD_SHARED(p)            CMM_ACCESS_ONCE(p)
  40
  41 /*
  42  * Load a data from shared memory, doing a cache flush if required.
  43  */
  44 #define CMM_LOAD_SHARED(p)                      \
  45         __extension__                   \
  46         ({                              \
  47                 cmm_smp_rmc();          \
  48                 _CMM_LOAD_SHARED(p);    \
  49         })
  50
  51 /*
  52  * Identify a shared store. A cmm_smp_wmc() or cmm_smp_mc() should
  53  * follow the store.
  54  */
  55 #define _CMM_STORE_SHARED(x, v) __extension__ ({ CMM_ACCESS_ONCE(x) = (v); })
  56
  57 /*
  58  * Store v into x, where x is located in shared memory. Performs the
  59  * required cache flush after writing. Returns v.
  60  */
  61 #define CMM_STORE_SHARED(x, v)                                          \
  62         __extension__                                                   \
  63         ({                                                              \
  64                 __typeof__(x) _v = _CMM_STORE_SHARED(x, v);             \
  65                 cmm_smp_wmc();                                          \
  66                 _v = _v;        /* Work around clang "unused result" */ \
  67         })
  68
  69 #endif  /* CONFIG_RCU_USE_ATOMIC_BUILTINS */
  70
  71 #endif /* _URCU_SYSTEM_H */