MdePkg/Library/BaseLib/SynchronizationGcc.c

   1 /** @file
   2   Implementation of synchronization functions.
   3
   4   Copyright (c) 2006 - 2008, 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 **/
  14
  15
  16
  17
  18 #include "BaseLibInternals.h"
  19
  20 //
  21 // GCC inline assembly for Read Write Barrier
  22 //
  23 #define _ReadWriteBarrier() do { asm volatile ("": : : "memory"); } while(0)
  24
  25 #define SPIN_LOCK_RELEASED          ((UINTN) 1)
  26 #define SPIN_LOCK_ACQUIRED          ((UINTN) 2)
  27
  28 /**
  29   Retrieves the architecture specific spin lock alignment requirements for
  30   optimal spin lock performance.
  31
  32   This function retrieves the spin lock alignment requirements for optimal
  33   performance on a given CPU architecture. The spin lock alignment must be a
  34   power of two and is returned by this function. If there are no alignment
  35   requirements, then 1 must be returned. The spin lock synchronization
  36   functions must function correctly if the spin lock size and alignment values
  37   returned by this function are not used at all. These values are hints to the
  38   consumers of the spin lock synchronization functions to obtain optimal spin
  39   lock performance.
  40
  41   @return The architecture specific spin lock alignment.
  42
  43 **/
  44 UINTN
  45 EFIAPI
  46 GetSpinLockProperties (
  47   VOID
  48   )
  49 {
  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 in release state.
  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 acquired lock.
 102
 103 **/
 104 SPIN_LOCK *
 105 EFIAPI
 106 AcquireSpinLock (
 107   IN OUT  SPIN_LOCK                 *SpinLock
 108   )
 109 {
 110   UINT64  Current;
 111   UINT64  Previous;
 112   UINT64  Total;
 113   UINT64  Start;
 114   UINT64  End;
 115   UINT64  Timeout;
 116   INT64   Cycle;
 117   INT64   Delta;
 118
 119   if (PcdGet32 (PcdSpinLockTimeout) > 0) {
 120     //
 121     // Get the current timer value
 122     //
 123     Current = GetPerformanceCounter();
 124
 125     //
 126     // Initialize local variables
 127     //
 128     Start = 0;
 129     End   = 0;
 130     Total = 0;
 131
 132     //
 133     // Retrieve the performance counter properties and compute the number of performance
 134     // counter ticks required to reach the timeout
 135     //
 136     Timeout = DivU64x32 (
 137                 MultU64x32 (
 138                   GetPerformanceCounterProperties (&Start, &End),
 139                   PcdGet32 (PcdSpinLockTimeout)
 140                   ),
 141                 1000000
 142                 );
 143     Cycle = End - Start;
 144     if (Cycle < 0) {
 145       Cycle = -Cycle;
 146     }
 147     Cycle++;
 148
 149     while (!AcquireSpinLockOrFail (SpinLock)) {
 150       CpuPause ();
 151       Previous = Current;
 152       Current  = GetPerformanceCounter();
 153       Delta = (INT64) (Current - Previous);
 154       if (Start > End) {
 155         Delta = -Delta;
 156       }
 157       if (Delta < 0) {
 158         Delta += Cycle;
 159       }
 160       Total += Delta;
 161       ASSERT (Total < Timeout);
 162     }
 163   } else {
 164     while (!AcquireSpinLockOrFail (SpinLock)) {
 165       CpuPause ();
 166     }
 167   }
 168   return SpinLock;
 169 }
 170
 171 /**
 172   Attempts to place a spin lock in the acquired state.
 173
 174   This function checks the state of the spin lock specified by SpinLock. If
 175   SpinLock is in the released state, then this function places SpinLock in the
 176   acquired state and returns TRUE. Otherwise, FALSE is returned. All state
 177   transitions of SpinLock must be performed using MP safe mechanisms.
 178
 179   If SpinLock is NULL, then ASSERT().
 180   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 181
 182   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 183
 184   @retval TRUE  SpinLock was placed in the acquired state.
 185   @retval FALSE SpinLock could not be acquired.
 186
 187 **/
 188 BOOLEAN
 189 EFIAPI
 190 AcquireSpinLockOrFail (
 191   IN OUT  SPIN_LOCK                 *SpinLock
 192   )
 193 {
 194   SPIN_LOCK   LockValue;
 195   VOID        *Result;
 196
 197   ASSERT (SpinLock != NULL);
 198
 199   LockValue = *SpinLock;
 200   ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);
 201
 202   _ReadWriteBarrier ();
 203   Result = InterlockedCompareExchangePointer (
 204              (VOID**)SpinLock,
 205              (VOID*)SPIN_LOCK_RELEASED,
 206              (VOID*)SPIN_LOCK_ACQUIRED
 207            );
 208
 209   _ReadWriteBarrier ();
 210   return (BOOLEAN) (Result == (VOID*) SPIN_LOCK_RELEASED);
 211 }
 212
 213 /**
 214   Releases a spin lock.
 215
 216   This function places the spin lock specified by SpinLock in the release state
 217   and returns SpinLock.
 218
 219   If SpinLock is NULL, then ASSERT().
 220   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 221
 222   @param  SpinLock  A pointer to the spin lock to release.
 223
 224   @return SpinLock released lock.
 225
 226 **/
 227 SPIN_LOCK *
 228 EFIAPI
 229 ReleaseSpinLock (
 230   IN OUT  SPIN_LOCK                 *SpinLock
 231   )
 232 {
 233   SPIN_LOCK    LockValue;
 234
 235   ASSERT (SpinLock != NULL);
 236
 237   LockValue = *SpinLock;
 238   ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);
 239
 240   _ReadWriteBarrier ();
 241   *SpinLock = SPIN_LOCK_RELEASED;
 242   _ReadWriteBarrier ();
 243
 244   return SpinLock;
 245 }
 246
 247 /**
 248   Performs an atomic increment of an 32-bit unsigned integer.
 249
 250   Performs an atomic increment of the 32-bit unsigned integer specified by
 251   Value and returns the incremented value. The increment operation must be
 252   performed using MP safe mechanisms. The state of the return value is not
 253   guaranteed to be MP safe.
 254
 255   If Value is NULL, then ASSERT().
 256
 257   @param  Value A pointer to the 32-bit value to increment.
 258
 259   @return The incremented value.
 260
 261 **/
 262 UINT32
 263 EFIAPI
 264 InterlockedIncrement (
 265   IN      UINT32                    *Value
 266   )
 267 {
 268   ASSERT (Value != NULL);
 269   return InternalSyncIncrement (Value);
 270 }
 271
 272 /**
 273   Performs an atomic decrement of an 32-bit unsigned integer.
 274
 275   Performs an atomic decrement of the 32-bit unsigned integer specified by
 276   Value and returns the decremented value. The decrement operation must be
 277   performed using MP safe mechanisms. The state of the return value is not
 278   guaranteed to be MP safe.
 279
 280   If Value is NULL, then ASSERT().
 281
 282   @param  Value A pointer to the 32-bit value to decrement.
 283
 284   @return The decremented value.
 285
 286 **/
 287 UINT32
 288 EFIAPI
 289 InterlockedDecrement (
 290   IN      UINT32                    *Value
 291   )
 292 {
 293   ASSERT (Value != NULL);
 294   return InternalSyncDecrement (Value);
 295 }
 296
 297 /**
 298   Performs an atomic compare exchange operation on a 32-bit unsigned integer.
 299
 300   Performs an atomic compare exchange operation on the 32-bit unsigned integer
 301   specified by Value.  If Value is equal to CompareValue, then Value is set to
 302   ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
 303   then Value is returned.  The compare exchange operation must be performed using
 304   MP safe mechanisms.
 305
 306   If Value is NULL, then ASSERT().
 307
 308   @param  Value         A pointer to the 32-bit value for the compare exchange
 309                         operation.
 310   @param  CompareValue  32-bit value used in compare operation.
 311   @param  ExchangeValue 32-bit value used in exchange operation.
 312
 313   @return The original *Value before exchange.
 314
 315 **/
 316 UINT32
 317 EFIAPI
 318 InterlockedCompareExchange32 (
 319   IN OUT  UINT32                    *Value,
 320   IN      UINT32                    CompareValue,
 321   IN      UINT32                    ExchangeValue
 322   )
 323 {
 324   ASSERT (Value != NULL);
 325   return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);
 326 }
 327
 328 /**
 329   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
 330
 331   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
 332   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
 333   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
 334   The compare exchange operation must be performed using MP safe mechanisms.
 335
 336   If Value is NULL, then ASSERT().
 337
 338   @param  Value         A pointer to the 64-bit value for the compare exchange
 339                         operation.
 340   @param  CompareValue  64-bit value used in compare operation.
 341   @param  ExchangeValue 64-bit value used in exchange operation.
 342
 343   @return The original *Value before exchange.
 344
 345 **/
 346 UINT64
 347 EFIAPI
 348 InterlockedCompareExchange64 (
 349   IN OUT  UINT64                    *Value,
 350   IN      UINT64                    CompareValue,
 351   IN      UINT64                    ExchangeValue
 352   )
 353 {
 354   ASSERT (Value != NULL);
 355   return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);
 356 }
 357
 358 /**
 359   Performs an atomic compare exchange operation on a pointer value.
 360
 361   Performs an atomic compare exchange operation on the pointer value specified
 362   by Value. If Value is equal to CompareValue, then Value is set to
 363   ExchangeValue and CompareValue is returned. If Value is not equal to
 364   CompareValue, then Value is returned. The compare exchange operation must be
 365   performed using MP safe mechanisms.
 366
 367   If Value is NULL, then ASSERT().
 368
 369   @param  Value         A pointer to the pointer value for the compare exchange
 370                         operation.
 371   @param  CompareValue  Pointer value used in compare operation.
 372   @param  ExchangeValue Pointer value used in exchange operation.
 373
 374   @return The original *Value before exchange.
 375 **/
 376 VOID *
 377 EFIAPI
 378 InterlockedCompareExchangePointer (
 379   IN OUT  VOID                      **Value,
 380   IN      VOID                      *CompareValue,
 381   IN      VOID                      *ExchangeValue
 382   )
 383 {
 384   UINT8  SizeOfValue;
 385
 386   SizeOfValue = sizeof (*Value);
 387
 388   switch (SizeOfValue) {
 389     case sizeof (UINT32):
 390       return (VOID*)(UINTN)InterlockedCompareExchange32 (
 391                              (UINT32*)Value,
 392                              (UINT32)(UINTN)CompareValue,
 393                              (UINT32)(UINTN)ExchangeValue
 394                              );
 395     case sizeof (UINT64):
 396       return (VOID*)(UINTN)InterlockedCompareExchange64 (
 397                              (UINT64*)Value,
 398                              (UINT64)(UINTN)CompareValue,
 399                              (UINT64)(UINTN)ExchangeValue
 400                              );
 401     default:
 402       ASSERT (FALSE);
 403       return NULL;
 404   }
 405 }