Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2010 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #include "Dalvik.h" |
| 18 | |
| 19 | #include <cutils/atomic.h> |
| 20 | |
| 21 | /* |
| 22 | * Quasi-atomic 64-bit operations, for platforms that lack the real thing. |
| 23 | * |
Andy McFadden | 38a1786 | 2010-06-16 16:28:07 -0700 | [diff] [blame] | 24 | * TODO: unify ARMv6/x86/sh implementations using the to-be-written |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 25 | * spin lock implementation. We don't want to rely on mutex innards, |
| 26 | * and it would be great if all platforms were running the same code. |
| 27 | */ |
| 28 | |
| 29 | #if defined(HAVE_MACOSX_IPC) |
| 30 | |
| 31 | #include <libkern/OSAtomic.h> |
| 32 | |
| 33 | #if defined(__ppc__) \ |
| 34 | || defined(__PPC__) \ |
| 35 | || defined(__powerpc__) \ |
| 36 | || defined(__powerpc) \ |
| 37 | || defined(__POWERPC__) \ |
| 38 | || defined(_M_PPC) \ |
| 39 | || defined(__PPC) |
| 40 | #define NEED_QUASIATOMICS 1 |
| 41 | #else |
| 42 | |
Andy McFadden | 6e10b9a | 2010-06-14 15:24:39 -0700 | [diff] [blame] | 43 | int dvmQuasiAtomicCas64(int64_t oldvalue, int64_t newvalue, |
| 44 | volatile int64_t* addr) |
| 45 | { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 46 | return OSAtomicCompareAndSwap64Barrier(oldvalue, newvalue, |
| 47 | (int64_t*)addr) == 0; |
| 48 | } |
| 49 | |
Andy McFadden | 6e10b9a | 2010-06-14 15:24:39 -0700 | [diff] [blame] | 50 | int64_t dvmQuasiAtomicSwap64(int64_t value, volatile int64_t* addr) |
| 51 | { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 52 | int64_t oldValue; |
| 53 | do { |
| 54 | oldValue = *addr; |
Andy McFadden | 38a1786 | 2010-06-16 16:28:07 -0700 | [diff] [blame] | 55 | } while (dvmQuasiAtomicCas64(oldValue, value, addr)); |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 56 | return oldValue; |
| 57 | } |
| 58 | |
Andy McFadden | c35a2ef | 2010-06-17 12:36:00 -0700 | [diff] [blame] | 59 | int64_t dvmQuasiAtomicRead64(volatile const int64_t* addr) |
Andy McFadden | 6e10b9a | 2010-06-14 15:24:39 -0700 | [diff] [blame] | 60 | { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 61 | return OSAtomicAdd64Barrier(0, addr); |
| 62 | } |
| 63 | #endif |
| 64 | |
| 65 | #elif defined(__i386__) || defined(__x86_64__) |
| 66 | #define NEED_QUASIATOMICS 1 |
| 67 | |
| 68 | #elif __arm__ |
Andy McFadden | 38a1786 | 2010-06-16 16:28:07 -0700 | [diff] [blame] | 69 | #include <machine/cpu-features.h> |
| 70 | |
| 71 | #ifdef __ARM_HAVE_LDREXD |
| 72 | int64_t dvmQuasiAtomicSwap64(int64_t newvalue, volatile int64_t* addr) |
| 73 | { |
| 74 | int64_t prev; |
| 75 | int status; |
| 76 | do { |
| 77 | __asm__ __volatile__ ("@ dvmQuasiAtomicSwap64\n" |
| 78 | "ldrexd %0, %H0, [%3]\n" |
| 79 | "strexd %1, %4, %H4, [%3]" |
| 80 | : "=&r" (prev), "=&r" (status), "+m"(*addr) |
| 81 | : "r" (addr), "r" (newvalue) |
| 82 | : "cc"); |
| 83 | } while (__builtin_expect(status != 0, 0)); |
| 84 | return prev; |
| 85 | } |
| 86 | |
| 87 | int dvmQuasiAtomicCas64(int64_t oldvalue, int64_t newvalue, |
| 88 | volatile int64_t* addr) |
| 89 | { |
| 90 | int64_t prev; |
| 91 | int status; |
| 92 | do { |
| 93 | __asm__ __volatile__ ("@ dvmQuasiAtomicCas64\n" |
| 94 | "ldrexd %0, %H0, [%3]\n" |
| 95 | "mov %1, #0\n" |
| 96 | "teq %0, %4\n" |
| 97 | "teqeq %H0, %H4\n" |
| 98 | "strexdeq %1, %5, %H5, [%3]" |
| 99 | : "=&r" (prev), "=&r" (status), "+m"(*addr) |
| 100 | : "r" (addr), "Ir" (oldvalue), "r" (newvalue) |
| 101 | : "cc"); |
| 102 | } while (__builtin_expect(status != 0, 0)); |
| 103 | return prev != oldvalue; |
| 104 | } |
| 105 | |
Andy McFadden | c35a2ef | 2010-06-17 12:36:00 -0700 | [diff] [blame] | 106 | int64_t dvmQuasiAtomicRead64(volatile const int64_t* addr) |
Andy McFadden | 38a1786 | 2010-06-16 16:28:07 -0700 | [diff] [blame] | 107 | { |
| 108 | int64_t value; |
| 109 | __asm__ __volatile__ ("@ dvmQuasiAtomicRead64\n" |
| 110 | "ldrexd %0, %H0, [%1]" |
| 111 | : "=&r" (value) |
| 112 | : "r" (addr)); |
| 113 | return value; |
| 114 | } |
| 115 | |
| 116 | #else |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 117 | |
| 118 | // on the device, we implement the 64-bit atomic operations through |
| 119 | // mutex locking. normally, this is bad because we must initialize |
| 120 | // a pthread_mutex_t before being able to use it, and this means |
| 121 | // having to do an initialization check on each function call, and |
| 122 | // that's where really ugly things begin... |
| 123 | // |
| 124 | // BUT, as a special twist, we take advantage of the fact that in our |
| 125 | // pthread library, a mutex is simply a volatile word whose value is always |
| 126 | // initialized to 0. In other words, simply declaring a static mutex |
| 127 | // object initializes it ! |
| 128 | // |
| 129 | // another twist is that we use a small array of mutexes to dispatch |
| 130 | // the contention locks from different memory addresses |
| 131 | // |
| 132 | |
| 133 | #include <pthread.h> |
| 134 | |
| 135 | #define SWAP_LOCK_COUNT 32U |
| 136 | static pthread_mutex_t _swap_locks[SWAP_LOCK_COUNT]; |
| 137 | |
| 138 | #define SWAP_LOCK(addr) \ |
| 139 | &_swap_locks[((unsigned)(void*)(addr) >> 3U) % SWAP_LOCK_COUNT] |
| 140 | |
| 141 | |
Andy McFadden | 6e10b9a | 2010-06-14 15:24:39 -0700 | [diff] [blame] | 142 | int64_t dvmQuasiAtomicSwap64(int64_t value, volatile int64_t* addr) |
| 143 | { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 144 | int64_t oldValue; |
| 145 | pthread_mutex_t* lock = SWAP_LOCK(addr); |
| 146 | |
| 147 | pthread_mutex_lock(lock); |
| 148 | |
| 149 | oldValue = *addr; |
| 150 | *addr = value; |
| 151 | |
| 152 | pthread_mutex_unlock(lock); |
| 153 | return oldValue; |
| 154 | } |
| 155 | |
Andy McFadden | 6e10b9a | 2010-06-14 15:24:39 -0700 | [diff] [blame] | 156 | int dvmQuasiAtomicCas64(int64_t oldvalue, int64_t newvalue, |
| 157 | volatile int64_t* addr) |
| 158 | { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 159 | int result; |
| 160 | pthread_mutex_t* lock = SWAP_LOCK(addr); |
| 161 | |
| 162 | pthread_mutex_lock(lock); |
| 163 | |
| 164 | if (*addr == oldvalue) { |
| 165 | *addr = newvalue; |
| 166 | result = 0; |
| 167 | } else { |
| 168 | result = 1; |
| 169 | } |
| 170 | pthread_mutex_unlock(lock); |
| 171 | return result; |
| 172 | } |
| 173 | |
Andy McFadden | c35a2ef | 2010-06-17 12:36:00 -0700 | [diff] [blame] | 174 | int64_t dvmQuasiAtomicRead64(volatile const int64_t* addr) |
Andy McFadden | 6e10b9a | 2010-06-14 15:24:39 -0700 | [diff] [blame] | 175 | { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 176 | int64_t result; |
| 177 | pthread_mutex_t* lock = SWAP_LOCK(addr); |
| 178 | |
| 179 | pthread_mutex_lock(lock); |
| 180 | result = *addr; |
| 181 | pthread_mutex_unlock(lock); |
| 182 | return result; |
| 183 | } |
| 184 | |
Andy McFadden | 38a1786 | 2010-06-16 16:28:07 -0700 | [diff] [blame] | 185 | #endif /*__ARM_HAVE_LDREXD*/ |
| 186 | |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 187 | /*****************************************************************************/ |
| 188 | #elif __sh__ |
| 189 | #define NEED_QUASIATOMICS 1 |
| 190 | |
| 191 | #else |
| 192 | #error "Unsupported atomic operations for this platform" |
| 193 | #endif |
| 194 | |
| 195 | |
| 196 | #if NEED_QUASIATOMICS |
| 197 | |
| 198 | /* Note that a spinlock is *not* a good idea in general |
| 199 | * since they can introduce subtle issues. For example, |
| 200 | * a real-time thread trying to acquire a spinlock already |
| 201 | * acquired by another thread will never yeld, making the |
| 202 | * CPU loop endlessly! |
| 203 | * |
| 204 | * However, this code is only used on the Linux simulator |
| 205 | * so it's probably ok for us. |
| 206 | * |
| 207 | * The alternative is to use a pthread mutex, but |
| 208 | * these must be initialized before being used, and |
| 209 | * then you have the problem of lazily initializing |
| 210 | * a mutex without any other synchronization primitive. |
Andy McFadden | fb07cb6 | 2010-05-27 10:23:41 -0700 | [diff] [blame] | 211 | * |
| 212 | * TODO: these currently use sched_yield(), which is not guaranteed to |
| 213 | * do anything at all. We need to use dvmIterativeSleep or a wait / |
| 214 | * notify mechanism if the initial attempt fails. |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 215 | */ |
| 216 | |
| 217 | /* global spinlock for all 64-bit quasiatomic operations */ |
| 218 | static int32_t quasiatomic_spinlock = 0; |
| 219 | |
Andy McFadden | 6e10b9a | 2010-06-14 15:24:39 -0700 | [diff] [blame] | 220 | int dvmQuasiAtomicCas64(int64_t oldvalue, int64_t newvalue, |
| 221 | volatile int64_t* addr) |
| 222 | { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 223 | int result; |
| 224 | |
Andy McFadden | fb07cb6 | 2010-05-27 10:23:41 -0700 | [diff] [blame] | 225 | while (android_atomic_acquire_cas(0, 1, &quasiatomic_spinlock)) { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 226 | #ifdef HAVE_WIN32_THREADS |
| 227 | Sleep(0); |
| 228 | #else |
| 229 | sched_yield(); |
| 230 | #endif |
| 231 | } |
| 232 | |
| 233 | if (*addr == oldvalue) { |
| 234 | *addr = newvalue; |
| 235 | result = 0; |
| 236 | } else { |
| 237 | result = 1; |
| 238 | } |
| 239 | |
Andy McFadden | fb07cb6 | 2010-05-27 10:23:41 -0700 | [diff] [blame] | 240 | android_atomic_release_store(0, &quasiatomic_spinlock); |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 241 | |
| 242 | return result; |
| 243 | } |
| 244 | |
Andy McFadden | c35a2ef | 2010-06-17 12:36:00 -0700 | [diff] [blame] | 245 | int64_t dvmQuasiAtomicRead64(volatile const int64_t* addr) |
Andy McFadden | 6e10b9a | 2010-06-14 15:24:39 -0700 | [diff] [blame] | 246 | { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 247 | int64_t result; |
| 248 | |
Andy McFadden | fb07cb6 | 2010-05-27 10:23:41 -0700 | [diff] [blame] | 249 | while (android_atomic_acquire_cas(0, 1, &quasiatomic_spinlock)) { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 250 | #ifdef HAVE_WIN32_THREADS |
| 251 | Sleep(0); |
| 252 | #else |
| 253 | sched_yield(); |
| 254 | #endif |
| 255 | } |
| 256 | |
| 257 | result = *addr; |
Andy McFadden | fb07cb6 | 2010-05-27 10:23:41 -0700 | [diff] [blame] | 258 | android_atomic_release_store(0, &quasiatomic_spinlock); |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 259 | |
| 260 | return result; |
| 261 | } |
| 262 | |
Andy McFadden | 6e10b9a | 2010-06-14 15:24:39 -0700 | [diff] [blame] | 263 | int64_t dvmQuasiAtomicSwap64(int64_t value, volatile int64_t* addr) |
| 264 | { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 265 | int64_t result; |
| 266 | |
Andy McFadden | fb07cb6 | 2010-05-27 10:23:41 -0700 | [diff] [blame] | 267 | while (android_atomic_acquire_cas(0, 1, &quasiatomic_spinlock)) { |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 268 | #ifdef HAVE_WIN32_THREADS |
| 269 | Sleep(0); |
| 270 | #else |
| 271 | sched_yield(); |
| 272 | #endif |
| 273 | } |
| 274 | |
| 275 | result = *addr; |
| 276 | *addr = value; |
Andy McFadden | fb07cb6 | 2010-05-27 10:23:41 -0700 | [diff] [blame] | 277 | android_atomic_release_store(0, &quasiatomic_spinlock); |
Andy McFadden | 6a87708 | 2010-05-19 22:36:33 -0700 | [diff] [blame] | 278 | |
| 279 | return result; |
| 280 | } |
| 281 | |
Andy McFadden | 38a1786 | 2010-06-16 16:28:07 -0700 | [diff] [blame] | 282 | #endif /*NEED_QUASIATOMICS*/ |