MdePkg/Library/BaseLib/Synchronization.c

   1 /** @file
   2   Implementation of synchronization functions.
   3
   4   Copyright (c) 2006, 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 // Include common header file for this module.
  17 //
  18
  19
  20 #include "BaseLibInternals.h"
  21
  22 #define SPIN_LOCK_RELEASED          ((UINTN) 1)
  23 #define SPIN_LOCK_ACQUIRED          ((UINTN) 2)
  24
  25 /**
  26   Retrieves the architecture specific spin lock alignment requirements for
  27   optimal spin lock performance.
  28
  29   This function retrieves the spin lock alignment requirements for optimal
  30   performance on a given CPU architecture. The spin lock alignment must be a
  31   power of two and is returned by this function. If there are no alignment
  32   requirements, then 1 must be returned. The spin lock synchronization
  33   functions must function correctly if the spin lock size and alignment values
  34   returned by this function are not used at all. These values are hints to the
  35   consumers of the spin lock synchronization functions to obtain optimal spin
  36   lock performance.
  37
  38   @return The architecture specific spin lock alignment.
  39
  40 **/
  41 UINTN
  42 EFIAPI
  43 GetSpinLockProperties (
  44   VOID
  45   )
  46 {
  47   return 32;
  48 }
  49
  50 /**
  51   Initializes a spin lock to the released state and returns the spin lock.
  52
  53   This function initializes the spin lock specified by SpinLock to the released
  54   state, and returns SpinLock. Optimal performance can be achieved by calling
  55   GetSpinLockProperties() to determine the size and alignment requirements for
  56   SpinLock.
  57
  58   If SpinLock is NULL, then ASSERT().
  59
  60   @param  SpinLock  A pointer to the spin lock to initialize to the released
  61                     state.
  62
  63   @return SpinLock initialized in release state.
  64
  65 **/
  66 SPIN_LOCK *
  67 EFIAPI
  68 InitializeSpinLock (
  69   OUT     SPIN_LOCK                 *SpinLock
  70   )
  71 {
  72   ASSERT (SpinLock != NULL);
  73   *SpinLock = SPIN_LOCK_RELEASED;
  74   return SpinLock;
  75 }
  76
  77 /**
  78   Waits until a spin lock can be placed in the acquired state.
  79
  80   This function checks the state of the spin lock specified by SpinLock. If
  81   SpinLock is in the released state, then this function places SpinLock in the
  82   acquired state and returns SpinLock. Otherwise, this function waits
  83   indefinitely for the spin lock to be released, and then places it in the
  84   acquired state and returns SpinLock. All state transitions of SpinLock must
  85   be performed using MP safe mechanisms.
  86
  87   If SpinLock is NULL, then ASSERT().
  88   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
  89   If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in
  90   PcdSpinLockTimeout microseconds, then ASSERT().
  91
  92   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
  93
  94   @return SpinLock aquired lock.
  95
  96 **/
  97 SPIN_LOCK *
  98 EFIAPI
  99 AcquireSpinLock (
 100   IN OUT  SPIN_LOCK                 *SpinLock
 101   )
 102 {
 103   UINT64  Current;
 104   UINT64  Previous;
 105   UINT64  Total;
 106   UINT64  Start;
 107   UINT64  End;
 108   UINT64  Timeout;
 109   INT64   Cycle;
 110   INT64   Delta;
 111
 112   if (PcdGet32 (PcdSpinLockTimeout) > 0) {
 113     //
 114     // Get the current timer value
 115     //
 116     Current = GetPerformanceCounter();
 117
 118     //
 119     // Initialize local variables
 120     //
 121     Start = 0;
 122     End   = 0;
 123     Total = 0;
 124
 125     //
 126     // Retrieve the performance counter properties and compute the number of performance
 127     // counter ticks required to reach the timeout
 128     //
 129     Timeout = DivU64x32 (
 130                 MultU64x32 (
 131                   GetPerformanceCounterProperties (&Start, &End),
 132                   PcdGet32 (PcdSpinLockTimeout)
 133                   ),
 134                 1000000
 135                 );
 136     Cycle = End - Start;
 137     if (Cycle < 0) {
 138       Cycle = -Cycle;
 139     }
 140     Cycle++;
 141
 142     while (!AcquireSpinLockOrFail (SpinLock)) {
 143       CpuPause ();
 144       Previous = Current;
 145       Current  = GetPerformanceCounter();
 146       Delta = (INT64) (Current - Previous);
 147       if (Start > End) {
 148         Delta = -Delta;
 149       }
 150       if (Delta < 0) {
 151         Delta += Cycle;
 152       }
 153       Total += Delta;
 154       ASSERT (Total < Timeout);
 155     }
 156   } else {
 157     while (!AcquireSpinLockOrFail (SpinLock)) {
 158       CpuPause ();
 159     }
 160   }
 161   return SpinLock;
 162 }
 163
 164 /**
 165   Attempts to place a spin lock in the acquired state.
 166
 167   This function checks the state of the spin lock specified by SpinLock. If
 168   SpinLock is in the released state, then this function places SpinLock in the
 169   acquired state and returns TRUE. Otherwise, FALSE is returned. All state
 170   transitions of SpinLock must be performed using MP safe mechanisms.
 171
 172   If SpinLock is NULL, then ASSERT().
 173   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 174
 175   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 176
 177   @retval TRUE  SpinLock was placed in the acquired state.
 178   @retval FALSE SpinLock could not be acquired.
 179
 180 **/
 181 BOOLEAN
 182 EFIAPI
 183 AcquireSpinLockOrFail (
 184   IN OUT  SPIN_LOCK                 *SpinLock
 185   )
 186 {
 187   SPIN_LOCK    LockValue;
 188
 189   ASSERT (SpinLock != NULL);
 190
 191   LockValue = *SpinLock;
 192   ASSERT (SPIN_LOCK_ACQUIRED == LockValue || SPIN_LOCK_RELEASED == LockValue);
 193
 194   return (BOOLEAN)(
 195            InterlockedCompareExchangePointer (
 196              (VOID**)SpinLock,
 197              (VOID*)SPIN_LOCK_RELEASED,
 198              (VOID*)SPIN_LOCK_ACQUIRED
 199              ) == (VOID*)SPIN_LOCK_RELEASED
 200            );
 201 }
 202
 203 /**
 204   Releases a spin lock.
 205
 206   This function places the spin lock specified by SpinLock in the release state
 207   and returns SpinLock.
 208
 209   If SpinLock is NULL, then ASSERT().
 210   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 211
 212   @param  SpinLock  A pointer to the spin lock to release.
 213
 214   @return SpinLock
 215
 216 **/
 217 SPIN_LOCK *
 218 EFIAPI
 219 ReleaseSpinLock (
 220   IN OUT  SPIN_LOCK                 *SpinLock
 221   )
 222 {
 223   SPIN_LOCK    LockValue;
 224
 225   ASSERT (SpinLock != NULL);
 226
 227   LockValue = *SpinLock;
 228   ASSERT (SPIN_LOCK_ACQUIRED == LockValue || SPIN_LOCK_RELEASED == LockValue);
 229
 230   *SpinLock = SPIN_LOCK_RELEASED;
 231   return SpinLock;
 232 }
 233
 234 /**
 235   Performs an atomic increment of an 32-bit unsigned integer.
 236
 237   Performs an atomic increment of the 32-bit unsigned integer specified by
 238   Value and returns the incremented value. The increment 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 increment.
 245
 246   @return The incremented value.
 247
 248 **/
 249 UINT32
 250 EFIAPI
 251 InterlockedIncrement (
 252   IN      UINT32                    *Value
 253   )
 254 {
 255   ASSERT (Value != NULL);
 256   return InternalSyncIncrement (Value);
 257 }
 258
 259 /**
 260   Performs an atomic decrement of an 32-bit unsigned integer.
 261
 262   Performs an atomic decrement of the 32-bit unsigned integer specified by
 263   Value and returns the decremented value. The decrement operation must be
 264   performed using MP safe mechanisms. The state of the return value is not
 265   guaranteed to be MP safe.
 266
 267   If Value is NULL, then ASSERT().
 268
 269   @param  Value A pointer to the 32-bit value to decrement.
 270
 271   @return The decremented value.
 272
 273 **/
 274 UINT32
 275 EFIAPI
 276 InterlockedDecrement (
 277   IN      UINT32                    *Value
 278   )
 279 {
 280   ASSERT (Value != NULL);
 281   return InternalSyncDecrement (Value);
 282 }
 283
 284 /**
 285   Performs an atomic compare exchange operation on a 32-bit unsigned integer.
 286
 287   Performs an atomic compare exchange operation on the 32-bit unsigned integer
 288   specified by Value.  If Value is equal to CompareValue, then Value is set to
 289   ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
 290   then Value is returned.  The compare exchange operation must be performed using
 291   MP safe mechanisms.
 292
 293   If Value is NULL, then ASSERT().
 294
 295   @param  Value         A pointer to the 32-bit value for the compare exchange
 296                         operation.
 297   @param  CompareValue  32-bit value used in compare operation.
 298   @param  ExchangeValue 32-bit value used in exchange operation.
 299
 300   @return The original *Value before exchange.
 301
 302 **/
 303 UINT32
 304 EFIAPI
 305 InterlockedCompareExchange32 (
 306   IN OUT  UINT32                    *Value,
 307   IN      UINT32                    CompareValue,
 308   IN      UINT32                    ExchangeValue
 309   )
 310 {
 311   ASSERT (Value != NULL);
 312   return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);
 313 }
 314
 315 /**
 316   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
 317
 318   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
 319   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
 320   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
 321   The compare exchange operation must be performed using MP safe mechanisms.
 322
 323   If Value is NULL, then ASSERT().
 324
 325   @param  Value         A pointer to the 64-bit value for the compare exchange
 326                         operation.
 327   @param  CompareValue  64-bit value used in compare operation.
 328   @param  ExchangeValue 64-bit value used in exchange operation.
 329
 330   @return The original *Value before exchange.
 331
 332 **/
 333 UINT64
 334 EFIAPI
 335 InterlockedCompareExchange64 (
 336   IN OUT  UINT64                    *Value,
 337   IN      UINT64                    CompareValue,
 338   IN      UINT64                    ExchangeValue
 339   )
 340 {
 341   ASSERT (Value != NULL);
 342   return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);
 343 }
 344
 345 /**
 346   Performs an atomic compare exchange operation on a pointer value.
 347
 348   Performs an atomic compare exchange operation on the pointer value specified
 349   by Value. If Value is equal to CompareValue, then Value is set to
 350   ExchangeValue and CompareValue is returned. If Value is not equal to
 351   CompareValue, then Value is returned. The compare exchange operation must be
 352   performed using MP safe mechanisms.
 353
 354   If Value is NULL, then ASSERT().
 355
 356   @param  Value         A pointer to the pointer value for the compare exchange
 357                         operation.
 358   @param  CompareValue  Pointer value used in compare operation.
 359   @param  ExchangeValue Pointer value used in exchange operation.
 360
 361   @return The original *Value before exchange.
 362
 363 **/
 364 VOID *
 365 EFIAPI
 366 InterlockedCompareExchangePointer (
 367   IN OUT  VOID                      **Value,
 368   IN      VOID                      *CompareValue,
 369   IN      VOID                      *ExchangeValue
 370   )
 371 {
 372   UINT8  SizeOfValue;
 373
 374   SizeOfValue = sizeof (*Value);
 375
 376   switch (SizeOfValue) {
 377     case sizeof (UINT32):
 378       return (VOID*)(UINTN)InterlockedCompareExchange32 (
 379                              (UINT32*)Value,
 380                              (UINT32)(UINTN)CompareValue,
 381                              (UINT32)(UINTN)ExchangeValue
 382                              );
 383     case sizeof (UINT64):
 384       return (VOID*)(UINTN)InterlockedCompareExchange64 (
 385                              (UINT64*)Value,
 386                              (UINT64)(UINTN)CompareValue,
 387                              (UINT64)(UINTN)ExchangeValue
 388                              );
 389     default:
 390       ASSERT (FALSE);
 391       return NULL;
 392   }
 393 }