1 /*
   2  * Copyright (c) 1999, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright (c) 2014, 2019, Red Hat Inc. All rights reserved.
   4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   5  *
   6  * This code is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License version 2 only, as
   8  * published by the Free Software Foundation.
   9  *
  10  * This code is distributed in the hope that it will be useful, but WITHOUT
  11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * version 2 for more details (a copy is included in the LICENSE file that
  14  * accompanied this code).
  15  *
  16  * You should have received a copy of the GNU General Public License version
  17  * 2 along with this work; if not, write to the Free Software Foundation,
  18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  19  *
  20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  21  * or visit www.oracle.com if you need additional information or have any
  22  * questions.
  23  *
  24  */
  25 
  26 #ifndef OS_CPU_LINUX_AARCH64_ATOMIC_LINUX_AARCH64_HPP
  27 #define OS_CPU_LINUX_AARCH64_ATOMIC_LINUX_AARCH64_HPP
  28 
  29 #include "runtime/vm_version.hpp"
  30 
  31 // Implementation of class atomic
  32 // Note that memory_order_conservative requires a full barrier after atomic stores.
  33 // See https://patchwork.kernel.org/patch/3575821/
  34 
  35 #define FULL_MEM_BARRIER  __sync_synchronize()
  36 #define READ_MEM_BARRIER  __atomic_thread_fence(__ATOMIC_ACQUIRE);
  37 #define WRITE_MEM_BARRIER __atomic_thread_fence(__ATOMIC_RELEASE);
  38 
  39 template<size_t byte_size>
  40 struct Atomic::PlatformAdd
  41   : Atomic::AddAndFetch<Atomic::PlatformAdd<byte_size> >
  42 {
  43   template<typename I, typename D>
  44   D add_and_fetch(I add_value, D volatile* dest, atomic_memory_order order) const {
  45     D res = __atomic_add_fetch(dest, add_value, __ATOMIC_RELEASE);
  46     FULL_MEM_BARRIER;
  47     return res;
  48   }
  49 };
  50 
  51 template<size_t byte_size>
  52 template<typename T>
  53 inline T Atomic::PlatformXchg<byte_size>::operator()(T exchange_value,
  54                                                      T volatile* dest,
  55                                                      atomic_memory_order order) const {
  56   STATIC_ASSERT(byte_size == sizeof(T));
  57   T res = __atomic_exchange_n(dest, exchange_value, __ATOMIC_RELEASE);
  58   FULL_MEM_BARRIER;
  59   return res;
  60 }
  61 
  62 template<size_t byte_size>
  63 template<typename T>
  64 inline T Atomic::PlatformCmpxchg<byte_size>::operator()(T exchange_value,
  65                                                         T volatile* dest,
  66                                                         T compare_value,
  67                                                         atomic_memory_order order) const {
  68   STATIC_ASSERT(byte_size == sizeof(T));
  69   if (order == memory_order_relaxed) {
  70     T value = compare_value;
  71     __atomic_compare_exchange(dest, &value, &exchange_value, /*weak*/false,
  72                               __ATOMIC_RELAXED, __ATOMIC_RELAXED);
  73     return value;
  74   } else {
  75     T value = compare_value;
  76     FULL_MEM_BARRIER;
  77     __atomic_compare_exchange(dest, &value, &exchange_value, /*weak*/false,
  78                               __ATOMIC_RELAXED, __ATOMIC_RELAXED);
  79     FULL_MEM_BARRIER;
  80     return value;
  81   }
  82 }
  83 
  84 #endif // OS_CPU_LINUX_AARCH64_ATOMIC_LINUX_AARCH64_HPP