/* * Copyright (c) 2014 Nicira, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* This header implements atomic operation primitives for MSVC * on i586 or greater platforms (32 bit). */ #ifndef IN_OVS_ATOMIC_H #error "This header should only be included indirectly via ovs-atomic.h." #endif /* From msdn documentation: With Visual Studio 2003, volatile to volatile * references are ordered; the compiler will not re-order volatile variable * access. With Visual Studio 2005, the compiler also uses acquire semantics * for read operations on volatile variables and release semantics for write * operations on volatile variables (when supported by the CPU). * * Though there is no clear documentation that states that anything greater * than VS 2005 has the same behavior as described above, looking through MSVCs * C++ atomics library in VS2013 shows that the compiler still takes * acquire/release semantics on volatile variables. */ #define ATOMIC(TYPE) TYPE volatile typedef enum { memory_order_relaxed, memory_order_consume, memory_order_acquire, memory_order_release, memory_order_acq_rel, memory_order_seq_cst } memory_order; #define ATOMIC_BOOL_LOCK_FREE 2 #define ATOMIC_CHAR_LOCK_FREE 2 #define ATOMIC_SHORT_LOCK_FREE 2 #define ATOMIC_INT_LOCK_FREE 2 #define ATOMIC_LONG_LOCK_FREE 2 #define ATOMIC_LLONG_LOCK_FREE 2 #define ATOMIC_POINTER_LOCK_FREE 2 #define IS_LOCKLESS_ATOMIC(OBJECT) \ (sizeof(OBJECT) <= 8 && IS_POW2(sizeof(OBJECT))) #define ATOMIC_VAR_INIT(VALUE) (VALUE) #define atomic_init(OBJECT, VALUE) (*(OBJECT) = (VALUE), (void) 0) static inline void atomic_compiler_barrier(memory_order order) { /* In case of 'memory_order_consume', it is implicitly assumed that * the compiler will not move instructions that have data-dependency * on the variable in question before the barrier. */ if (order > memory_order_consume) { _ReadWriteBarrier(); } } static inline void atomic_thread_fence(memory_order order) { /* x86 is strongly ordered and acquire/release semantics come * automatically. */ atomic_compiler_barrier(order); if (order == memory_order_seq_cst) { MemoryBarrier(); atomic_compiler_barrier(order); } } static inline void atomic_signal_fence(memory_order order) { atomic_compiler_barrier(order); } /* 1, 2 and 4 bytes loads and stores are atomic on aligned memory. In addition, * since the compiler automatically takes acquire and release semantics on * volatile variables, for any order lesser than 'memory_order_seq_cst', we * can directly assign or read values. */ #define atomic_store32(DST, SRC, ORDER) \ if (ORDER == memory_order_seq_cst) { \ InterlockedExchange((int32_t volatile *) (DST), \ (int32_t) (SRC)); \ } else { \ *(DST) = (SRC); \ } /* 64 bit writes are atomic on i586 if 64 bit aligned. */ #define atomic_store64(DST, SRC, ORDER) \ if (((size_t) (DST) & (sizeof *(DST) - 1)) \ || ORDER == memory_order_seq_cst) { \ InterlockedExchange64((int64_t volatile *) (DST), \ (int64_t) (SRC)); \ } else { \ *(DST) = (SRC); \ } /* Used for 8 and 16 bit variations. */ #define atomic_storeX(X, DST, SRC, ORDER) \ if (ORDER == memory_order_seq_cst) { \ InterlockedExchange##X((int##X##_t volatile *) (DST), \ (int##X##_t) (SRC)); \ } else { \ *(DST) = (SRC); \ } #define atomic_store(DST, SRC) \ atomic_store_explicit(DST, SRC, memory_order_seq_cst) #define atomic_store_explicit(DST, SRC, ORDER) \ if (sizeof *(DST) == 1) { \ atomic_storeX(8, DST, SRC, ORDER) \ } else if (sizeof *(DST) == 2) { \ atomic_storeX(16, DST, SRC, ORDER) \ } else if (sizeof *(DST) == 4) { \ atomic_store32(DST, SRC, ORDER) \ } else if (sizeof *(DST) == 8) { \ atomic_store64(DST, SRC, ORDER) \ } else { \ abort(); \ } /* On x86, for 'memory_order_seq_cst', if stores are locked, the corresponding * reads don't need to be locked (based on the following in Intel Developers * manual: * “Locked operations are atomic with respect to all other memory operations * and all externally visible events. Only instruction fetch and page table * accesses can pass locked instructions. Locked instructions can be used to * synchronize data written by one processor and read by another processor. * For the P6 family processors, locked operations serialize all outstanding * load and store operations (that is, wait for them to complete). This rule * is also true for the Pentium 4 and Intel Xeon processors, with one * exception. Load operations that reference weakly ordered memory types * (such as the WC memory type) may not be serialized."). */ /* For 8, 16 and 32 bit variations. */ #define atomic_readX(SRC, DST, ORDER) \ *(DST) = *(SRC); /* 64 bit reads are atomic on i586 if 64 bit aligned. */ #define atomic_read64(SRC, DST, ORDER) \ if (((size_t) (SRC) & (sizeof *(SRC) - 1)) == 0) { \ *(DST) = *(SRC); \ } else { \ *(DST) = InterlockedOr64((int64_t volatile *) (SRC), 0); \ } #define atomic_read(SRC, DST) \ atomic_read_explicit(SRC, DST, memory_order_seq_cst) #define atomic_read_explicit(SRC, DST, ORDER) \ if (sizeof *(DST) == 1 || sizeof *(DST) == 2 || sizeof *(DST) == 4) { \ atomic_readX(SRC, DST, ORDER) \ } else if (sizeof *(DST) == 8) { \ atomic_read64(SRC, DST, ORDER) \ } else { \ abort(); \ } /* For add, sub, and logical operations, for 8, 16 and 64 bit data types, * functions for all the different memory orders does not exist * (though documentation exists for some of them). The MSVC C++ library which * implements the c11 atomics simply calls the full memory barrier function * for everything in x86(see xatomic.h). So do the same here. */ /* For 8, 16 and 64 bit variations. */ #define atomic_op(OP, X, RMW, ARG, ORIG, ORDER) \ atomic_##OP##_generic(X, RMW, ARG, ORIG, ORDER) /* Arithmetic addition calls. */ #define atomic_add32(RMW, ARG, ORIG, ORDER) \ *(ORIG) = InterlockedExchangeAdd((int32_t volatile *) (RMW), \ (int32_t) (ARG)); /* For 8, 16 and 64 bit variations. */ #define atomic_add_generic(X, RMW, ARG, ORIG, ORDER) \ *(ORIG) = _InterlockedExchangeAdd##X((int##X##_t volatile *) (RMW), \ (int##X##_t) (ARG)); #define atomic_add(RMW, ARG, ORIG) \ atomic_add_explicit(RMW, ARG, ORIG, memory_order_seq_cst) #define atomic_add_explicit(RMW, ARG, ORIG, ORDER) \ if (sizeof *(RMW) == 1) { \ atomic_op(add, 8, RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 2) { \ atomic_op(add, 16, RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 4) { \ atomic_add32(RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 8) { \ atomic_op(add, 64, RMW, ARG, ORIG, ORDER) \ } else { \ abort(); \ } /* Arithmetic subtraction calls. */ #define atomic_sub(RMW, ARG, ORIG) \ atomic_add_explicit(RMW, (0 - (ARG)), ORIG, memory_order_seq_cst) #define atomic_sub_explicit(RMW, ARG, ORIG, ORDER) \ atomic_add_explicit(RMW, (0 - (ARG)), ORIG, ORDER) /* Logical 'and' calls. */ #define atomic_and32(RMW, ARG, ORIG, ORDER) \ *(ORIG) = InterlockedAnd((int32_t volatile *) (RMW), (int32_t) (ARG)); /* For 8, 16 and 64 bit variations. */ #define atomic_and_generic(X, RMW, ARG, ORIG, ORDER) \ *(ORIG) = InterlockedAnd##X((int##X##_t volatile *) (RMW), \ (int##X##_t) (ARG)); #define atomic_and(RMW, ARG, ORIG) \ atomic_and_explicit(RMW, ARG, ORIG, memory_order_seq_cst) #define atomic_and_explicit(RMW, ARG, ORIG, ORDER) \ if (sizeof *(RMW) == 1) { \ atomic_op(and, 8, RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 2) { \ atomic_op(and, 16, RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 4) { \ atomic_and32(RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 8) { \ atomic_op(and, 64, RMW, ARG, ORIG, ORDER) \ } else { \ abort(); \ } /* Logical 'Or' calls. */ #define atomic_or32(RMW, ARG, ORIG, ORDER) \ *(ORIG) = InterlockedOr((int32_t volatile *) (RMW), (int32_t) (ARG)); /* For 8, 16 and 64 bit variations. */ #define atomic_or_generic(X, RMW, ARG, ORIG, ORDER) \ *(ORIG) = InterlockedOr##X((int##X##_t volatile *) (RMW), \ (int##X##_t) (ARG)); #define atomic_or(RMW, ARG, ORIG) \ atomic_or_explicit(RMW, ARG, ORIG, memory_order_seq_cst) #define atomic_or_explicit(RMW, ARG, ORIG, ORDER) \ if (sizeof *(RMW) == 1) { \ atomic_op(or, 8, RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 2) { \ atomic_op(or, 16, RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 4) { \ atomic_or32(RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 8) { \ atomic_op(or, 64, RMW, ARG, ORIG, ORDER) \ } else { \ abort(); \ } /* Logical Xor calls. */ #define atomic_xor32(RMW, ARG, ORIG, ORDER) \ *(ORIG) = InterlockedXor((int32_t volatile *) (RMW), (int32_t) (ARG)); /* For 8, 16 and 64 bit variations. */ #define atomic_xor_generic(X, RMW, ARG, ORIG, ORDER) \ *(ORIG) = InterlockedXor##X((int##X##_t volatile *) (RMW), \ (int##X##_t) (ARG)); #define atomic_xor(RMW, ARG, ORIG) \ atomic_xor_explicit(RMW, ARG, ORIG, memory_order_seq_cst) #define atomic_xor_explicit(RMW, ARG, ORIG, ORDER) \ if (sizeof *(RMW) == 1) { \ atomic_op(xor, 8, RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 2) { \ atomic_op(xor, 16, RMW, ARG, ORIG, ORDER) \ } else if (sizeof *(RMW) == 4) { \ atomic_xor32(RMW, ARG, ORIG, ORDER); \ } else if (sizeof *(RMW) == 8) { \ atomic_op(xor, 64, RMW, ARG, ORIG, ORDER) \ } else { \ abort(); \ } #define atomic_compare_exchange_strong(DST, EXP, SRC) \ atomic_compare_exchange_strong_explicit(DST, EXP, SRC, \ memory_order_seq_cst, \ memory_order_seq_cst) #define atomic_compare_exchange_weak atomic_compare_exchange_strong #define atomic_compare_exchange_weak_explicit \ atomic_compare_exchange_strong_explicit /* MSVCs c++ compiler implements c11 atomics and looking through its * implementation (in xatomic.h), orders are ignored for x86 platform. * Do the same here. */ static inline bool atomic_compare_exchange8(int8_t volatile *dst, int8_t *expected, int8_t src) { int8_t previous = _InterlockedCompareExchange8(dst, src, *expected); if (previous == *expected) { return true; } else { *expected = previous; return false; } } static inline bool atomic_compare_exchange16(int16_t volatile *dst, int16_t *expected, int16_t src) { int16_t previous = InterlockedCompareExchange16(dst, src, *expected); if (previous == *expected) { return true; } else { *expected = previous; return false; } } static inline bool atomic_compare_exchange32(int32_t volatile *dst, int32_t *expected, int32_t src) { int32_t previous = InterlockedCompareExchange(dst, src, *expected); if (previous == *expected) { return true; } else { *expected = previous; return false; } } static inline bool atomic_compare_exchange64(int64_t volatile *dst, int64_t *expected, int64_t src) { int64_t previous = InterlockedCompareExchange64(dst, src, *expected); if (previous == *expected) { return true; } else { *expected = previous; return false; } } static inline bool atomic_compare_unreachable() { return true; } #define atomic_compare_exchange_strong_explicit(DST, EXP, SRC, ORD1, ORD2) \ (sizeof *(DST) == 1 \ ? atomic_compare_exchange8((int8_t volatile *) (DST), (int8_t *) (EXP), \ (int8_t) (SRC)) \ : (sizeof *(DST) == 2 \ ? atomic_compare_exchange16((int16_t volatile *) (DST), \ (int16_t *) (EXP), (int16_t) (SRC)) \ : (sizeof *(DST) == 4 \ ? atomic_compare_exchange32((int32_t volatile *) (DST), \ (int32_t *) (EXP), (int32_t) (SRC)) \ : (sizeof *(DST) == 8 \ ? atomic_compare_exchange64((int64_t volatile *) (DST), \ (int64_t *) (EXP), (int64_t) (SRC)) \ : ovs_fatal(0, "atomic operation with size greater than 8 bytes"), \ atomic_compare_unreachable())))) /* atomic_flag */ typedef ATOMIC(int32_t) atomic_flag; #define ATOMIC_FLAG_INIT 0 #define atomic_flag_test_and_set(FLAG) \ (bool) InterlockedBitTestAndSet(FLAG, 0) #define atomic_flag_test_and_set_explicit(FLAG, ORDER) \ atomic_flag_test_and_set(FLAG) #define atomic_flag_clear_explicit(FLAG, ORDER) \ atomic_flag_clear() #define atomic_flag_clear(FLAG) \ InterlockedBitTestAndReset(FLAG, 0)