1 /* 2 * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved. 3 * Copyright 2007, 2008, 2011, 2015, Red Hat, Inc. 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_ZERO_VM_ATOMIC_LINUX_ZERO_HPP 27 #define OS_CPU_LINUX_ZERO_VM_ATOMIC_LINUX_ZERO_HPP 28 29 #include "runtime/os.hpp" 30 31 // Implementation of class atomic 32 33 #ifdef M68K 34 35 /* 36 * __m68k_cmpxchg 37 * 38 * Atomically store newval in *ptr if *ptr is equal to oldval for user space. 39 * Returns newval on success and oldval if no exchange happened. 40 * This implementation is processor specific and works on 41 * 68020 68030 68040 and 68060. 42 * 43 * It will not work on ColdFire, 68000 and 68010 since they lack the CAS 44 * instruction. 45 * Using a kernelhelper would be better for arch complete implementation. 46 * 47 */ 48 49 static inline int __m68k_cmpxchg(int oldval, int newval, volatile int *ptr) { 50 int ret; 51 __asm __volatile ("cas%.l %0,%2,%1" 52 : "=d" (ret), "+m" (*(ptr)) 53 : "d" (newval), "0" (oldval)); 54 return ret; 55 } 56 57 /* Perform an atomic compare and swap: if the current value of `*PTR' 58 is OLDVAL, then write NEWVAL into `*PTR'. Return the contents of 59 `*PTR' before the operation.*/ 60 static inline int m68k_compare_and_swap(int newval, 61 volatile int *ptr, 62 int oldval) { 63 for (;;) { 64 int prev = *ptr; 65 if (prev != oldval) 66 return prev; 67 68 if (__m68k_cmpxchg (prev, newval, ptr) == newval) 69 // Success. 70 return prev; 71 72 // We failed even though prev == oldval. Try again. 73 } 74 } 75 76 /* Atomically add an int to memory. */ 77 static inline int m68k_add_and_fetch(volatile int *ptr, int add_value) { 78 for (;;) { 79 // Loop until success. 80 81 int prev = *ptr; 82 83 if (__m68k_cmpxchg (prev, prev + add_value, ptr) == prev + add_value) 84 return prev + add_value; 85 } 86 } 87 88 /* Atomically write VALUE into `*PTR' and returns the previous 89 contents of `*PTR'. */ 90 static inline int m68k_lock_test_and_set(volatile int *ptr, int newval) { 91 for (;;) { 92 // Loop until success. 93 int prev = *ptr; 94 95 if (__m68k_cmpxchg (prev, newval, ptr) == prev) 96 return prev; 97 } 98 } 99 #endif // M68K 100 101 #ifdef ARM 102 103 /* 104 * __kernel_cmpxchg 105 * 106 * Atomically store newval in *ptr if *ptr is equal to oldval for user space. 107 * Return zero if *ptr was changed or non-zero if no exchange happened. 108 * The C flag is also set if *ptr was changed to allow for assembly 109 * optimization in the calling code. 110 * 111 */ 112 113 typedef int (__kernel_cmpxchg_t)(int oldval, int newval, volatile int *ptr); 114 #define __kernel_cmpxchg (*(__kernel_cmpxchg_t *) 0xffff0fc0) 115 116 117 118 /* Perform an atomic compare and swap: if the current value of `*PTR' 119 is OLDVAL, then write NEWVAL into `*PTR'. Return the contents of 120 `*PTR' before the operation.*/ 121 static inline int arm_compare_and_swap(int newval, 122 volatile int *ptr, 123 int oldval) { 124 for (;;) { 125 int prev = *ptr; 126 if (prev != oldval) 127 return prev; 128 129 if (__kernel_cmpxchg (prev, newval, ptr) == 0) 130 // Success. 131 return prev; 132 133 // We failed even though prev == oldval. Try again. 134 } 135 } 136 137 /* Atomically add an int to memory. */ 138 static inline int arm_add_and_fetch(volatile int *ptr, int add_value) { 139 for (;;) { 140 // Loop until a __kernel_cmpxchg succeeds. 141 142 int prev = *ptr; 143 144 if (__kernel_cmpxchg (prev, prev + add_value, ptr) == 0) 145 return prev + add_value; 146 } 147 } 148 149 /* Atomically write VALUE into `*PTR' and returns the previous 150 contents of `*PTR'. */ 151 static inline int arm_lock_test_and_set(volatile int *ptr, int newval) { 152 for (;;) { 153 // Loop until a __kernel_cmpxchg succeeds. 154 int prev = *ptr; 155 156 if (__kernel_cmpxchg (prev, newval, ptr) == 0) 157 return prev; 158 } 159 } 160 #endif // ARM 161 162 inline void Atomic::store(jint store_value, volatile jint* dest) { 163 *dest = store_value; 164 } 165 166 inline void Atomic::store_ptr(intptr_t store_value, intptr_t* dest) { 167 *dest = store_value; 168 } 169 170 inline jint Atomic::add(jint add_value, volatile jint* dest) { 171 #ifdef ARM 172 return arm_add_and_fetch(dest, add_value); 173 #else 174 #ifdef M68K 175 return m68k_add_and_fetch(dest, add_value); 176 #else 177 return __sync_add_and_fetch(dest, add_value); 178 #endif // M68K 179 #endif // ARM 180 } 181 182 inline intptr_t Atomic::add_ptr(intptr_t add_value, volatile intptr_t* dest) { 183 #ifdef ARM 184 return arm_add_and_fetch(dest, add_value); 185 #else 186 #ifdef M68K 187 return m68k_add_and_fetch(dest, add_value); 188 #else 189 return __sync_add_and_fetch(dest, add_value); 190 #endif // M68K 191 #endif // ARM 192 } 193 194 inline void* Atomic::add_ptr(intptr_t add_value, volatile void* dest) { 195 return (void *) add_ptr(add_value, (volatile intptr_t *) dest); 196 } 197 198 inline void Atomic::inc(volatile jint* dest) { 199 add(1, dest); 200 } 201 202 inline void Atomic::inc_ptr(volatile intptr_t* dest) { 203 add_ptr(1, dest); 204 } 205 206 inline void Atomic::inc_ptr(volatile void* dest) { 207 add_ptr(1, dest); 208 } 209 210 inline void Atomic::dec(volatile jint* dest) { 211 add(-1, dest); 212 } 213 214 inline void Atomic::dec_ptr(volatile intptr_t* dest) { 215 add_ptr(-1, dest); 216 } 217 218 inline void Atomic::dec_ptr(volatile void* dest) { 219 add_ptr(-1, dest); 220 } 221 222 inline jint Atomic::xchg(jint exchange_value, volatile jint* dest) { 223 #ifdef ARM 224 return arm_lock_test_and_set(dest, exchange_value); 225 #else 226 #ifdef M68K 227 return m68k_lock_test_and_set(dest, exchange_value); 228 #else 229 // __sync_lock_test_and_set is a bizarrely named atomic exchange 230 // operation. Note that some platforms only support this with the 231 // limitation that the only valid value to store is the immediate 232 // constant 1. There is a test for this in JNI_CreateJavaVM(). 233 jint result = __sync_lock_test_and_set (dest, exchange_value); 234 // All atomic operations are expected to be full memory barriers 235 // (see atomic.hpp). However, __sync_lock_test_and_set is not 236 // a full memory barrier, but an acquire barrier. Hence, this added 237 // barrier. 238 __sync_synchronize(); 239 return result; 240 #endif // M68K 241 #endif // ARM 242 } 243 244 inline intptr_t Atomic::xchg_ptr(intptr_t exchange_value, 245 volatile intptr_t* dest) { 246 #ifdef ARM 247 return arm_lock_test_and_set(dest, exchange_value); 248 #else 249 #ifdef M68K 250 return m68k_lock_test_and_set(dest, exchange_value); 251 #else 252 intptr_t result = __sync_lock_test_and_set (dest, exchange_value); 253 __sync_synchronize(); 254 return result; 255 #endif // M68K 256 #endif // ARM 257 } 258 259 inline void* Atomic::xchg_ptr(void* exchange_value, volatile void* dest) { 260 return (void *) xchg_ptr((intptr_t) exchange_value, 261 (volatile intptr_t*) dest); 262 } 263 264 // No direct support for cmpxchg of bytes; emulate using int. 265 template<> 266 struct Atomic::PlatformCmpxchg<1> : Atomic::CmpxchgByteUsingInt {}; 267 268 template<> 269 template<typename T> 270 inline T Atomic::PlatformCmpxchg<4>::operator()(T exchange_value, 271 T volatile* dest, 272 T compare_value, 273 cmpxchg_memory_order order) { 274 STATIC_ASSERT(4 == sizeof(T)); 275 #ifdef ARM 276 return cmpxchg_using_helper<int>(arm_compare_and_swap, exchange_value, dest, compare_value); 277 #else 278 #ifdef M68K 279 return cmpxchg_using_helper<int>(m68k_compare_and_swap, exchange_value, dest, compare_value); 280 #else 281 return __sync_val_compare_and_swap(dest, compare_value, exchange_value); 282 #endif // M68K 283 #endif // ARM 284 } 285 286 template<> 287 template<typename T> 288 inline T Atomic::PlatformCmpxchg<8>::operator()(T exchange_value, 289 T volatile* dest, 290 T compare_value, 291 cmpxchg_memory_order order) { 292 STATIC_ASSERT(8 == sizeof(T)); 293 return __sync_val_compare_and_swap(dest, compare_value, exchange_value); 294 } 295 296 inline jlong Atomic::load(const volatile jlong* src) { 297 volatile jlong dest; 298 os::atomic_copy64(src, &dest); 299 return dest; 300 } 301 302 inline void Atomic::store(jlong store_value, jlong* dest) { 303 os::atomic_copy64((volatile jlong*)&store_value, (volatile jlong*)dest); 304 } 305 306 inline void Atomic::store(jlong store_value, volatile jlong* dest) { 307 os::atomic_copy64((volatile jlong*)&store_value, dest); 308 } 309 310 #endif // OS_CPU_LINUX_ZERO_VM_ATOMIC_LINUX_ZERO_HPP