MdePkg/Library/BaseLib/SynchronizationGcc.c

   1 /** @file
   2   Implementation of synchronization functions.
   3
   4   Copyright (c) 2006 - 2007, Intel Corporation<BR>
   5   All rights reserved. This program and the accompanying materials
   6   are licensed and made available under the terms and conditions of the BSD License
   7   which accompanies this distribution.  The full text of the license may be found at
   8   http://opensource.org/licenses/bsd-license.php
   9
  10   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  11   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  12
  13   Module Name:  SynchronizationGcc.c
  14
  15 **/
  16
  17 #include "BaseLibInternals.h"
  18
  19 //
  20 // GCC inline assembly for Read Write Barrier
  21 //
  22 #define _ReadWriteBarrier() do { asm volatile ("": : : "memory"); } while(0)
  23
  24 #define SPIN_LOCK_RELEASED          ((UINTN) 1)
  25 #define SPIN_LOCK_ACQUIRED          ((UINTN) 2)
  26
  27 /**
  28   Retrieves the architecture specific spin lock alignment requirements for
  29   optimal spin lock performance.
  30
  31   This function retrieves the spin lock alignment requirements for optimal
  32   performance on a given CPU architecture. The spin lock alignment must be a
  33   power of two and is returned by this function. If there are no alignment
  34   requirements, then 1 must be returned. The spin lock synchronization
  35   functions must function correctly if the spin lock size and alignment values
  36   returned by this function are not used at all. These values are hints to the
  37   consumers of the spin lock synchronization functions to obtain optimal spin
  38   lock performance.
  39
  40   @return The architecture specific spin lock alignment.
  41
  42 **/
  43 UINTN
  44 EFIAPI
  45 GetSpinLockProperties (
  46   VOID
  47   )
  48 {
  49   // @bug May use a PCD entry to determine this alignment.
  50   return 32;
  51 }
  52
  53 /**
  54   Initializes a spin lock to the released state and returns the spin lock.
  55
  56   This function initializes the spin lock specified by SpinLock to the released
  57   state, and returns SpinLock. Optimal performance can be achieved by calling
  58   GetSpinLockProperties() to determine the size and alignment requirements for
  59   SpinLock.
  60
  61   If SpinLock is NULL, then ASSERT().
  62
  63   @param  SpinLock  A pointer to the spin lock to initialize to the released
  64                     state.
  65
  66   @return SpinLock
  67
  68 **/
  69 SPIN_LOCK *
  70 EFIAPI
  71 InitializeSpinLock (
  72   OUT     SPIN_LOCK                 *SpinLock
  73   )
  74 {
  75   ASSERT (SpinLock != NULL);
  76
  77   _ReadWriteBarrier();
  78   *SpinLock = SPIN_LOCK_RELEASED;
  79   _ReadWriteBarrier();
  80
  81   return SpinLock;
  82 }
  83
  84 /**
  85   Waits until a spin lock can be placed in the acquired state.
  86
  87   This function checks the state of the spin lock specified by SpinLock. If
  88   SpinLock is in the released state, then this function places SpinLock in the
  89   acquired state and returns SpinLock. Otherwise, this function waits
  90   indefinitely for the spin lock to be released, and then places it in the
  91   acquired state and returns SpinLock. All state transitions of SpinLock must
  92   be performed using MP safe mechanisms.
  93
  94   If SpinLock is NULL, then ASSERT().
  95   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
  96   If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in
  97   PcdSpinLockTimeout microseconds, then ASSERT().
  98
  99   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 100
 101   @return SpinLock
 102
 103 **/
 104 SPIN_LOCK *
 105 EFIAPI
 106 AcquireSpinLock (
 107   IN OUT  SPIN_LOCK                 *SpinLock
 108   )
 109 {
 110   UINT64                            Tick;
 111   UINT64                            Start, End;
 112   UINT64                            Timeout;
 113
 114   Tick = 0;
 115   Start = 0;
 116   End = 0;
 117   if (PcdGet32 (PcdSpinLockTimeout) > 0) {
 118     Tick = GetPerformanceCounter ();
 119     Timeout = DivU64x32 (
 120                 MultU64x32 (
 121                   GetPerformanceCounterProperties (&Start, &End),
 122                   PcdGet32 (PcdSpinLockTimeout)
 123                   ),
 124                 1000000
 125                 );
 126     if (Start < End) {
 127       Tick += Timeout;
 128     } else {
 129       Tick -= Timeout;
 130     }
 131   }
 132
 133   while (!AcquireSpinLockOrFail (SpinLock)) {
 134     CpuPause ();
 135     ASSERT ((Start < End) ^ (Tick <= GetPerformanceCounter ()));
 136   }
 137   return SpinLock;
 138 }
 139
 140 /**
 141   Attempts to place a spin lock in the acquired state.
 142
 143   This function checks the state of the spin lock specified by SpinLock. If
 144   SpinLock is in the released state, then this function places SpinLock in the
 145   acquired state and returns TRUE. Otherwise, FALSE is returned. All state
 146   transitions of SpinLock must be performed using MP safe mechanisms.
 147
 148   If SpinLock is NULL, then ASSERT().
 149   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 150
 151   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 152
 153   @retval TRUE  SpinLock was placed in the acquired state.
 154   @retval FALSE SpinLock could not be acquired.
 155
 156 **/
 157 BOOLEAN
 158 EFIAPI
 159 AcquireSpinLockOrFail (
 160   IN OUT  SPIN_LOCK                 *SpinLock
 161   )
 162 {
 163   VOID  *Result;
 164
 165   ASSERT (SpinLock != NULL);
 166   ASSERT (*SpinLock == SPIN_LOCK_ACQUIRED || *SpinLock == SPIN_LOCK_RELEASED);
 167
 168   _ReadWriteBarrier ();
 169   Result = InterlockedCompareExchangePointer (
 170              (VOID**)SpinLock,
 171              (VOID*)SPIN_LOCK_RELEASED,
 172              (VOID*)SPIN_LOCK_ACQUIRED
 173            );
 174
 175   _ReadWriteBarrier ();
 176   return (BOOLEAN) (Result == (VOID*) SPIN_LOCK_RELEASED);
 177 }
 178
 179 /**
 180   Releases a spin lock.
 181
 182   This function places the spin lock specified by SpinLock in the release state
 183   and returns SpinLock.
 184
 185   If SpinLock is NULL, then ASSERT().
 186   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 187
 188   @param  SpinLock  A pointer to the spin lock to release.
 189
 190   @return SpinLock
 191
 192 **/
 193 SPIN_LOCK *
 194 EFIAPI
 195 ReleaseSpinLock (
 196   IN OUT  SPIN_LOCK                 *SpinLock
 197   )
 198 {
 199   ASSERT (SpinLock != NULL);
 200   ASSERT (*SpinLock == SPIN_LOCK_ACQUIRED || *SpinLock == SPIN_LOCK_RELEASED);
 201
 202   _ReadWriteBarrier ();
 203   *SpinLock = SPIN_LOCK_RELEASED;
 204   _ReadWriteBarrier ();
 205
 206   return SpinLock;
 207 }
 208
 209 /**
 210   Performs an atomic increment of an 32-bit unsigned integer.
 211
 212   Performs an atomic increment of the 32-bit unsigned integer specified by
 213   Value and returns the incremented value. The increment operation must be
 214   performed using MP safe mechanisms. The state of the return value is not
 215   guaranteed to be MP safe.
 216
 217   If Value is NULL, then ASSERT().
 218
 219   @param  Value A pointer to the 32-bit value to increment.
 220
 221   @return The incremented value.
 222
 223 **/
 224 UINT32
 225 EFIAPI
 226 InterlockedIncrement (
 227   IN      UINT32                    *Value
 228   )
 229 {
 230   ASSERT (Value != NULL);
 231   return InternalSyncIncrement (Value);
 232 }
 233
 234 /**
 235   Performs an atomic decrement of an 32-bit unsigned integer.
 236
 237   Performs an atomic decrement of the 32-bit unsigned integer specified by
 238   Value and returns the decremented value. The decrement operation must be
 239   performed using MP safe mechanisms. The state of the return value is not
 240   guaranteed to be MP safe.
 241
 242   If Value is NULL, then ASSERT().
 243
 244   @param  Value A pointer to the 32-bit value to decrement.
 245
 246   @return The decremented value.
 247
 248 **/
 249 UINT32
 250 EFIAPI
 251 InterlockedDecrement (
 252   IN      UINT32                    *Value
 253   )
 254 {
 255   ASSERT (Value != NULL);
 256   return InternalSyncDecrement (Value);
 257 }
 258
 259 /**
 260   Performs an atomic compare exchange operation on a 32-bit unsigned integer.
 261
 262   Performs an atomic compare exchange operation on the 32-bit unsigned integer
 263   specified by Value.  If Value is equal to CompareValue, then Value is set to
 264   ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
 265   then Value is returned.  The compare exchange operation must be performed using
 266   MP safe mechanisms.
 267
 268   If Value is NULL, then ASSERT().
 269
 270   @param  Value         A pointer to the 32-bit value for the compare exchange
 271                         operation.
 272   @param  CompareValue  32-bit value used in compare operation.
 273   @param  ExchangeValue 32-bit value used in exchange operation.
 274
 275   @return The original *Value before exchange.
 276
 277 **/
 278 UINT32
 279 EFIAPI
 280 InterlockedCompareExchange32 (
 281   IN OUT  UINT32                    *Value,
 282   IN      UINT32                    CompareValue,
 283   IN      UINT32                    ExchangeValue
 284   )
 285 {
 286   ASSERT (Value != NULL);
 287   return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);
 288 }
 289
 290 /**
 291   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
 292
 293   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
 294   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
 295   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
 296   The compare exchange operation must be performed using MP safe mechanisms.
 297
 298   If Value is NULL, then ASSERT().
 299
 300   @param  Value         A pointer to the 64-bit value for the compare exchange
 301                         operation.
 302   @param  CompareValue  64-bit value used in compare operation.
 303   @param  ExchangeValue 64-bit value used in exchange operation.
 304
 305   @return The original *Value before exchange.
 306
 307 **/
 308 UINT64
 309 EFIAPI
 310 InterlockedCompareExchange64 (
 311   IN OUT  UINT64                    *Value,
 312   IN      UINT64                    CompareValue,
 313   IN      UINT64                    ExchangeValue
 314   )
 315 {
 316   ASSERT (Value != NULL);
 317   return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);
 318 }
 319
 320 /**
 321   Performs an atomic compare exchange operation on a pointer value.
 322
 323   Performs an atomic compare exchange operation on the pointer value specified
 324   by Value. If Value is equal to CompareValue, then Value is set to
 325   ExchangeValue and CompareValue is returned. If Value is not equal to
 326   CompareValue, then Value is returned. The compare exchange operation must be
 327   performed using MP safe mechanisms.
 328
 329   If Value is NULL, then ASSERT().
 330
 331   @param  Value         A pointer to the pointer value for the compare exchange
 332                         operation.
 333   @param  CompareValue  Pointer value used in compare operation.
 334   @param  ExchangeValue Pointer value used in exchange operation.
 335
 336 **/
 337 VOID *
 338 EFIAPI
 339 InterlockedCompareExchangePointer (
 340   IN OUT  VOID                      **Value,
 341   IN      VOID                      *CompareValue,
 342   IN      VOID                      *ExchangeValue
 343   )
 344 {
 345   UINT8  SizeOfValue;
 346
 347   SizeOfValue = sizeof (*Value);
 348
 349   switch (SizeOfValue) {
 350     case sizeof (UINT32):
 351       return (VOID*)(UINTN)InterlockedCompareExchange32 (
 352                              (UINT32*)Value,
 353                              (UINT32)(UINTN)CompareValue,
 354                              (UINT32)(UINTN)ExchangeValue
 355                              );
 356     case sizeof (UINT64):
 357       return (VOID*)(UINTN)InterlockedCompareExchange64 (
 358                              (UINT64*)Value,
 359                              (UINT64)(UINTN)CompareValue,
 360                              (UINT64)(UINTN)ExchangeValue
 361                              );
 362     default:
 363       ASSERT (FALSE);
 364       return NULL;
 365   }
 366 }