1 /*
   2  * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * Copyright 2007, 2008, 2011 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_INLINE_HPP
  27 #define OS_CPU_LINUX_ZERO_VM_ATOMIC_LINUX_ZERO_INLINE_HPP
  28 
  29 #include "runtime/atomic.hpp"
  30 #include "runtime/os.hpp"
  31 #include "vm_version_zero.hpp"
  32 
  33 // Implementation of class atomic
  34 
  35 #ifdef M68K
  36 
  37 /*
  38  * __m68k_cmpxchg
  39  *
  40  * Atomically store newval in *ptr if *ptr is equal to oldval for user space.
  41  * Returns newval on success and oldval if no exchange happened.
  42  * This implementation is processor specific and works on
  43  * 68020 68030 68040 and 68060.
  44  *
  45  * It will not work on ColdFire, 68000 and 68010 since they lack the CAS
  46  * instruction.
  47  * Using a kernelhelper would be better for arch complete implementation.
  48  *
  49  */
  50 
  51 static inline int __m68k_cmpxchg(int oldval, int newval, volatile int *ptr) {
  52   int ret;
  53   __asm __volatile ("cas%.l %0,%2,%1"
  54                    : "=d" (ret), "+m" (*(ptr))
  55                    : "d" (newval), "0" (oldval));
  56   return ret;
  57 }
  58 
  59 /* Perform an atomic compare and swap: if the current value of `*PTR'
  60    is OLDVAL, then write NEWVAL into `*PTR'.  Return the contents of
  61    `*PTR' before the operation.*/
  62 static inline int m68k_compare_and_swap(volatile int *ptr,
  63                                         int oldval,
  64                                         int newval) {
  65   for (;;) {
  66       int prev = *ptr;
  67       if (prev != oldval)
  68         return prev;
  69 
  70       if (__m68k_cmpxchg (prev, newval, ptr) == newval)
  71         // Success.
  72         return prev;
  73 
  74       // We failed even though prev == oldval.  Try again.
  75     }
  76 }
  77 
  78 /* Atomically add an int to memory.  */
  79 static inline int m68k_add_and_fetch(volatile int *ptr, int add_value) {
  80   for (;;) {
  81       // Loop until success.
  82 
  83       int prev = *ptr;
  84 
  85       if (__m68k_cmpxchg (prev, prev + add_value, ptr) == prev + add_value)
  86         return prev + add_value;
  87     }
  88 }
  89 
  90 /* Atomically write VALUE into `*PTR' and returns the previous
  91    contents of `*PTR'.  */
  92 static inline int m68k_lock_test_and_set(volatile int *ptr, int newval) {
  93   for (;;) {
  94       // Loop until success.
  95       int prev = *ptr;
  96 
  97       if (__m68k_cmpxchg (prev, newval, ptr) == prev)
  98         return prev;
  99     }
 100 }
 101 #endif // M68K
 102 
 103 #ifdef ARM
 104 
 105 /*
 106  * __kernel_cmpxchg
 107  *
 108  * Atomically store newval in *ptr if *ptr is equal to oldval for user space.
 109  * Return zero if *ptr was changed or non-zero if no exchange happened.
 110  * The C flag is also set if *ptr was changed to allow for assembly
 111  * optimization in the calling code.
 112  *
 113  */
 114 
 115 typedef int (__kernel_cmpxchg_t)(int oldval, int newval, volatile int *ptr);
 116 #define __kernel_cmpxchg (*(__kernel_cmpxchg_t *) 0xffff0fc0)
 117 
 118 
 119 
 120 /* Perform an atomic compare and swap: if the current value of `*PTR'
 121    is OLDVAL, then write NEWVAL into `*PTR'.  Return the contents of
 122    `*PTR' before the operation.*/
 123 static inline int arm_compare_and_swap(volatile int *ptr,
 124                                        int oldval,
 125                                        int newval) {
 126   for (;;) {
 127       int prev = *ptr;
 128       if (prev != oldval)
 129         return prev;
 130 
 131       if (__kernel_cmpxchg (prev, newval, ptr) == 0)
 132         // Success.
 133         return prev;
 134 
 135       // We failed even though prev == oldval.  Try again.
 136     }
 137 }
 138 
 139 /* Atomically add an int to memory.  */
 140 static inline int arm_add_and_fetch(volatile int *ptr, int add_value) {
 141   for (;;) {
 142       // Loop until a __kernel_cmpxchg succeeds.
 143 
 144       int prev = *ptr;
 145 
 146       if (__kernel_cmpxchg (prev, prev + add_value, ptr) == 0)
 147         return prev + add_value;
 148     }
 149 }
 150 
 151 /* Atomically write VALUE into `*PTR' and returns the previous
 152    contents of `*PTR'.  */
 153 static inline int arm_lock_test_and_set(volatile int *ptr, int newval) {
 154   for (;;) {
 155       // Loop until a __kernel_cmpxchg succeeds.
 156       int prev = *ptr;
 157 
 158       if (__kernel_cmpxchg (prev, newval, ptr) == 0)
 159         return prev;
 160     }
 161 }
 162 #endif // ARM
 163 
 164 inline void Atomic::store(jint store_value, volatile jint* dest) {
 165   *dest = store_value;
 166 }
 167 
 168 inline void Atomic::store_ptr(intptr_t store_value, intptr_t* dest) {
 169   *dest = store_value;
 170 }
 171 
 172 inline jint Atomic::add(jint add_value, volatile jint* dest) {
 173 #ifdef ARM
 174   return arm_add_and_fetch(dest, add_value);
 175 #else
 176 #ifdef M68K
 177   return m68k_add_and_fetch(dest, add_value);
 178 #else
 179   return __sync_add_and_fetch(dest, add_value);
 180 #endif // M68K
 181 #endif // ARM
 182 }
 183 
 184 inline intptr_t Atomic::add_ptr(intptr_t add_value, volatile intptr_t* dest) {
 185 #ifdef ARM
 186   return arm_add_and_fetch(dest, add_value);
 187 #else
 188 #ifdef M68K
 189   return m68k_add_and_fetch(dest, add_value);
 190 #else
 191   return __sync_add_and_fetch(dest, add_value);
 192 #endif // M68K
 193 #endif // ARM
 194 }
 195 
 196 inline void* Atomic::add_ptr(intptr_t add_value, volatile void* dest) {
 197   return (void *) add_ptr(add_value, (volatile intptr_t *) dest);
 198 }
 199 
 200 inline void Atomic::inc(volatile jint* dest) {
 201   add(1, dest);
 202 }
 203 
 204 inline void Atomic::inc_ptr(volatile intptr_t* dest) {
 205   add_ptr(1, dest);
 206 }
 207 
 208 inline void Atomic::inc_ptr(volatile void* dest) {
 209   add_ptr(1, dest);
 210 }
 211 
 212 inline void Atomic::dec(volatile jint* dest) {
 213   add(-1, dest);
 214 }
 215 
 216 inline void Atomic::dec_ptr(volatile intptr_t* dest) {
 217   add_ptr(-1, dest);
 218 }
 219 
 220 inline void Atomic::dec_ptr(volatile void* dest) {
 221   add_ptr(-1, dest);
 222 }
 223 
 224 inline jint Atomic::xchg(jint exchange_value, volatile jint* dest) {
 225 #ifdef ARM
 226   return arm_lock_test_and_set(dest, exchange_value);
 227 #else
 228 #ifdef M68K
 229   return m68k_lock_test_and_set(dest, exchange_value);
 230 #else
 231   // __sync_lock_test_and_set is a bizarrely named atomic exchange
 232   // operation.  Note that some platforms only support this with the
 233   // limitation that the only valid value to store is the immediate
 234   // constant 1.  There is a test for this in JNI_CreateJavaVM().
 235   return __sync_lock_test_and_set (dest, exchange_value);
 236 #endif // M68K
 237 #endif // ARM
 238 }
 239 
 240 inline intptr_t Atomic::xchg_ptr(intptr_t exchange_value,
 241                                  volatile intptr_t* dest) {
 242 #ifdef ARM
 243   return arm_lock_test_and_set(dest, exchange_value);
 244 #else
 245 #ifdef M68K
 246   return m68k_lock_test_and_set(dest, exchange_value);
 247 #else
 248   return __sync_lock_test_and_set (dest, exchange_value);
 249 #endif // M68K
 250 #endif // ARM
 251 }
 252 
 253 inline void* Atomic::xchg_ptr(void* exchange_value, volatile void* dest) {
 254   return (void *) xchg_ptr((intptr_t) exchange_value,
 255                            (volatile intptr_t*) dest);
 256 }
 257 
 258 inline jint Atomic::cmpxchg(jint exchange_value,
 259                             volatile jint* dest,
 260                             jint compare_value) {
 261 #ifdef ARM
 262   return arm_compare_and_swap(dest, compare_value, exchange_value);
 263 #else
 264 #ifdef M68K
 265   return m68k_compare_and_swap(dest, compare_value, exchange_value);
 266 #else
 267   return __sync_val_compare_and_swap(dest, compare_value, exchange_value);
 268 #endif // M68K
 269 #endif // ARM
 270 }
 271 
 272 inline jlong Atomic::cmpxchg(jlong exchange_value,
 273                              volatile jlong* dest,
 274                              jlong compare_value) {
 275 
 276   return __sync_val_compare_and_swap(dest, compare_value, exchange_value);
 277 }
 278 
 279 inline intptr_t Atomic::cmpxchg_ptr(intptr_t exchange_value,
 280                                     volatile intptr_t* dest,
 281                                     intptr_t compare_value) {
 282 #ifdef ARM
 283   return arm_compare_and_swap(dest, compare_value, exchange_value);
 284 #else
 285 #ifdef M68K
 286   return m68k_compare_and_swap(dest, compare_value, exchange_value);
 287 #else
 288   return __sync_val_compare_and_swap(dest, compare_value, exchange_value);
 289 #endif // M68K
 290 #endif // ARM
 291 }
 292 
 293 inline void* Atomic::cmpxchg_ptr(void* exchange_value,
 294                                  volatile void* dest,
 295                                  void* compare_value) {
 296 
 297   return (void *) cmpxchg_ptr((intptr_t) exchange_value,
 298                               (volatile intptr_t*) dest,
 299                               (intptr_t) compare_value);
 300 }
 301 
 302 inline jlong Atomic::load(volatile jlong* src) {
 303   volatile jlong dest;
 304   os::atomic_copy64(src, &dest);
 305   return dest;
 306 }
 307 
 308 inline void Atomic::store(jlong store_value, jlong* dest) {
 309   os::atomic_copy64((volatile jlong*)&store_value, (volatile jlong*)dest);
 310 }
 311 
 312 inline void Atomic::store(jlong store_value, volatile jlong* dest) {
 313   os::atomic_copy64((volatile jlong*)&store_value, dest);
 314 }
 315 
 316 #endif // OS_CPU_LINUX_ZERO_VM_ATOMIC_LINUX_ZERO_INLINE_HPP