144 lines
5.6 KiB
C++
144 lines
5.6 KiB
C++
/*
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* Copyright (c) 2008, 2019, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#ifndef OS_CPU_LINUX_ARM_ATOMIC_LINUX_ARM_HPP
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#define OS_CPU_LINUX_ARM_ATOMIC_LINUX_ARM_HPP
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#include "runtime/os.hpp"
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#include "runtime/vm_version.hpp"
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// Implementation of class atomic
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/*
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* Atomic long operations on 32-bit ARM
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* ARM v7 supports LDREXD/STREXD synchronization instructions so no problem.
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* ARM < v7 does not have explicit 64 atomic load/store capability.
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* However, gcc emits LDRD/STRD instructions on v5te and LDM/STM on v5t
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* when loading/storing 64 bits.
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* For non-MP machines (which is all we support for ARM < v7)
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* under current Linux distros these instructions appear atomic.
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* See section A3.5.3 of ARM Architecture Reference Manual for ARM v7.
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* Also, for cmpxchg64, if ARM < v7 we check for cmpxchg64 support in the
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* Linux kernel using _kuser_helper_version. See entry-armv.S in the Linux
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* kernel source or kernel_user_helpers.txt in Linux Doc.
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*/
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template<>
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template<typename T>
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inline T Atomic::PlatformLoad<8>::operator()(T const volatile* src) const {
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STATIC_ASSERT(8 == sizeof(T));
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return PrimitiveConversions::cast<T>(
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(*os::atomic_load_long_func)(reinterpret_cast<const volatile int64_t*>(src)));
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}
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template<>
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template<typename T>
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inline void Atomic::PlatformStore<8>::operator()(T volatile* dest,
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T store_value) const {
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STATIC_ASSERT(8 == sizeof(T));
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(*os::atomic_store_long_func)(
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PrimitiveConversions::cast<int64_t>(store_value), reinterpret_cast<volatile int64_t*>(dest));
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}
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// As per atomic.hpp all read-modify-write operations have to provide two-way
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// barriers semantics.
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//
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// For ARMv7 we add explicit barriers in the stubs.
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template<size_t byte_size>
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struct Atomic::PlatformAdd {
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template<typename D, typename I>
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D add_and_fetch(D volatile* dest, I add_value, atomic_memory_order order) const;
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template<typename D, typename I>
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D fetch_and_add(D volatile* dest, I add_value, atomic_memory_order order) const {
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return add_and_fetch(dest, add_value, order) - add_value;
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}
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};
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template<>
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template<typename D, typename I>
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inline D Atomic::PlatformAdd<4>::add_and_fetch(D volatile* dest, I add_value,
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atomic_memory_order order) const {
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STATIC_ASSERT(4 == sizeof(I));
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STATIC_ASSERT(4 == sizeof(D));
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return add_using_helper<int32_t>(os::atomic_add_func, dest, add_value);
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}
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template<>
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template<typename T>
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inline T Atomic::PlatformXchg<4>::operator()(T volatile* dest,
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T exchange_value,
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atomic_memory_order order) const {
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STATIC_ASSERT(4 == sizeof(T));
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return xchg_using_helper<int32_t>(os::atomic_xchg_func, dest, exchange_value);
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}
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// The memory_order parameter is ignored - we always provide the strongest/most-conservative ordering
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// No direct support for cmpxchg of bytes; emulate using int.
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template<>
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struct Atomic::PlatformCmpxchg<1> : Atomic::CmpxchgByteUsingInt {};
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inline int32_t reorder_cmpxchg_func(int32_t exchange_value,
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int32_t volatile* dest,
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int32_t compare_value) {
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// Warning: Arguments are swapped to avoid moving them for kernel call
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return (*os::atomic_cmpxchg_func)(compare_value, exchange_value, dest);
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}
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inline int64_t reorder_cmpxchg_long_func(int64_t exchange_value,
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int64_t volatile* dest,
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int64_t compare_value) {
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assert(VM_Version::supports_cx8(), "Atomic compare and exchange int64_t not supported on this architecture!");
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// Warning: Arguments are swapped to avoid moving them for kernel call
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return (*os::atomic_cmpxchg_long_func)(compare_value, exchange_value, dest);
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}
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template<>
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template<typename T>
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inline T Atomic::PlatformCmpxchg<4>::operator()(T volatile* dest,
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T compare_value,
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T exchange_value,
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atomic_memory_order order) const {
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STATIC_ASSERT(4 == sizeof(T));
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return cmpxchg_using_helper<int32_t>(reorder_cmpxchg_func, dest, compare_value, exchange_value);
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}
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template<>
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template<typename T>
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inline T Atomic::PlatformCmpxchg<8>::operator()(T volatile* dest,
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T compare_value,
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T exchange_value,
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atomic_memory_order order) const {
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STATIC_ASSERT(8 == sizeof(T));
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return cmpxchg_using_helper<int64_t>(reorder_cmpxchg_long_func, dest, compare_value, exchange_value);
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}
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#endif // OS_CPU_LINUX_ARM_ATOMIC_LINUX_ARM_HPP
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