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   // @bug May use a PCD entry to determine this alignment.
  48   return 32;
  49 }
  50
  51 /**
  52   Initializes a spin lock to the released state and returns the spin lock.
  53
  54   This function initializes the spin lock specified by SpinLock to the released
  55   state, and returns SpinLock. Optimal performance can be achieved by calling
  56   GetSpinLockProperties() to determine the size and alignment requirements for
  57   SpinLock.
  58
  59   If SpinLock is NULL, then ASSERT().
  60
  61   @param  SpinLock  A pointer to the spin lock to initialize to the released
  62                     state.
  63
  64   @return SpinLock
  65
  66 **/
  67 SPIN_LOCK *
  68 EFIAPI
  69 InitializeSpinLock (
  70   OUT     SPIN_LOCK                 *SpinLock
  71   )
  72 {
  73   ASSERT (SpinLock != NULL);
  74   *SpinLock = SPIN_LOCK_RELEASED;
  75   return SpinLock;
  76 }
  77
  78 /**
  79   Waits until a spin lock can be placed in the acquired state.
  80
  81   This function checks the state of the spin lock specified by SpinLock. If
  82   SpinLock is in the released state, then this function places SpinLock in the
  83   acquired state and returns SpinLock. Otherwise, this function waits
  84   indefinitely for the spin lock to be released, and then places it in the
  85   acquired state and returns SpinLock. All state transitions of SpinLock must
  86   be performed using MP safe mechanisms.
  87
  88   If SpinLock is NULL, then ASSERT().
  89   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
  90   If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in
  91   PcdSpinLockTimeout microseconds, then ASSERT().
  92
  93   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
  94
  95   @return SpinLock
  96
  97 **/
  98 SPIN_LOCK *
  99 EFIAPI
 100 AcquireSpinLock (
 101   IN OUT  SPIN_LOCK                 *SpinLock
 102   )
 103 {
 104   UINT64                            Tick;
 105   UINT64                            Start, End;
 106   UINT64                            Timeout;
 107
 108   Tick = 0;
 109   Start = 0;
 110   End = 0;
 111   if (PcdGet32 (PcdSpinLockTimeout) > 0) {
 112     Tick = GetPerformanceCounter ();
 113     Timeout = DivU64x32 (
 114                 MultU64x32 (
 115                   GetPerformanceCounterProperties (&Start, &End),
 116                   PcdGet32 (PcdSpinLockTimeout)
 117                   ),
 118                 1000000
 119                 );
 120     if (Start < End) {
 121       Tick += Timeout;
 122     } else {
 123       Tick -= Timeout;
 124     }
 125   }
 126
 127   while (!AcquireSpinLockOrFail (SpinLock)) {
 128     CpuPause ();
 129     ASSERT ((Start < End) ^ (Tick <= GetPerformanceCounter ()));
 130   }
 131   return SpinLock;
 132 }
 133
 134 /**
 135   Attempts to place a spin lock in the acquired state.
 136
 137   This function checks the state of the spin lock specified by SpinLock. If
 138   SpinLock is in the released state, then this function places SpinLock in the
 139   acquired state and returns TRUE. Otherwise, FALSE is returned. All state
 140   transitions of SpinLock must be performed using MP safe mechanisms.
 141
 142   If SpinLock is NULL, then ASSERT().
 143   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 144
 145   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 146
 147   @retval TRUE  SpinLock was placed in the acquired state.
 148   @retval FALSE SpinLock could not be acquired.
 149
 150 **/
 151 BOOLEAN
 152 EFIAPI
 153 AcquireSpinLockOrFail (
 154   IN OUT  SPIN_LOCK                 *SpinLock
 155   )
 156 {
 157   SPIN_LOCK    LockValue;
 158
 159   ASSERT (SpinLock != NULL);
 160
 161   LockValue = *SpinLock;
 162   ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);
 163
 164   return (BOOLEAN)(
 165            InterlockedCompareExchangePointer (
 166              (VOID**)SpinLock,
 167              (VOID*)SPIN_LOCK_RELEASED,
 168              (VOID*)SPIN_LOCK_ACQUIRED
 169              ) == (VOID*)SPIN_LOCK_RELEASED
 170            );
 171 }
 172
 173 /**
 174   Releases a spin lock.
 175
 176   This function places the spin lock specified by SpinLock in the release state
 177   and returns SpinLock.
 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 release.
 183
 184   @return SpinLock
 185
 186 **/
 187 SPIN_LOCK *
 188 EFIAPI
 189 ReleaseSpinLock (
 190   IN OUT  SPIN_LOCK                 *SpinLock
 191   )
 192 {
 193   SPIN_LOCK    LockValue;
 194
 195   ASSERT (SpinLock != NULL);
 196
 197   LockValue = *SpinLock;
 198   ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);
 199
 200   *SpinLock = SPIN_LOCK_RELEASED;
 201   return SpinLock;
 202 }
 203
 204 /**
 205   Performs an atomic increment of an 32-bit unsigned integer.
 206
 207   Performs an atomic increment of the 32-bit unsigned integer specified by
 208   Value and returns the incremented value. The increment operation must be
 209   performed using MP safe mechanisms. The state of the return value is not
 210   guaranteed to be MP safe.
 211
 212   If Value is NULL, then ASSERT().
 213
 214   @param  Value A pointer to the 32-bit value to increment.
 215
 216   @return The incremented value.
 217
 218 **/
 219 UINT32
 220 EFIAPI
 221 InterlockedIncrement (
 222   IN      UINT32                    *Value
 223   )
 224 {
 225   ASSERT (Value != NULL);
 226   return InternalSyncIncrement (Value);
 227 }
 228
 229 /**
 230   Performs an atomic decrement of an 32-bit unsigned integer.
 231
 232   Performs an atomic decrement of the 32-bit unsigned integer specified by
 233   Value and returns the decremented value. The decrement operation must be
 234   performed using MP safe mechanisms. The state of the return value is not
 235   guaranteed to be MP safe.
 236
 237   If Value is NULL, then ASSERT().
 238
 239   @param  Value A pointer to the 32-bit value to decrement.
 240
 241   @return The decremented value.
 242
 243 **/
 244 UINT32
 245 EFIAPI
 246 InterlockedDecrement (
 247   IN      UINT32                    *Value
 248   )
 249 {
 250   ASSERT (Value != NULL);
 251   return InternalSyncDecrement (Value);
 252 }
 253
 254 /**
 255   Performs an atomic compare exchange operation on a 32-bit unsigned integer.
 256
 257   Performs an atomic compare exchange operation on the 32-bit unsigned integer
 258   specified by Value.  If Value is equal to CompareValue, then Value is set to
 259   ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
 260   then Value is returned.  The compare exchange operation must be performed using
 261   MP safe mechanisms.
 262
 263   If Value is NULL, then ASSERT().
 264
 265   @param  Value         A pointer to the 32-bit value for the compare exchange
 266                         operation.
 267   @param  CompareValue  32-bit value used in compare operation.
 268   @param  ExchangeValue 32-bit value used in exchange operation.
 269
 270   @return The original *Value before exchange.
 271
 272 **/
 273 UINT32
 274 EFIAPI
 275 InterlockedCompareExchange32 (
 276   IN OUT  UINT32                    *Value,
 277   IN      UINT32                    CompareValue,
 278   IN      UINT32                    ExchangeValue
 279   )
 280 {
 281   ASSERT (Value != NULL);
 282   return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);
 283 }
 284
 285 /**
 286   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
 287
 288   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
 289   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
 290   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
 291   The compare exchange operation must be performed using MP safe mechanisms.
 292
 293   If Value is NULL, then ASSERT().
 294
 295   @param  Value         A pointer to the 64-bit value for the compare exchange
 296                         operation.
 297   @param  CompareValue  64-bit value used in compare operation.
 298   @param  ExchangeValue 64-bit value used in exchange operation.
 299
 300   @return The original *Value before exchange.
 301
 302 **/
 303 UINT64
 304 EFIAPI
 305 InterlockedCompareExchange64 (
 306   IN OUT  UINT64                    *Value,
 307   IN      UINT64                    CompareValue,
 308   IN      UINT64                    ExchangeValue
 309   )
 310 {
 311   ASSERT (Value != NULL);
 312   return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);
 313 }
 314
 315 /**
 316   Performs an atomic compare exchange operation on a pointer value.
 317
 318   Performs an atomic compare exchange operation on the pointer value specified
 319   by Value. If Value is equal to CompareValue, then Value is set to
 320   ExchangeValue and CompareValue is returned. If Value is not equal to
 321   CompareValue, then Value is returned. The compare exchange operation must be
 322   performed using MP safe mechanisms.
 323
 324   If Value is NULL, then ASSERT().
 325
 326   @param  Value         A pointer to the pointer value for the compare exchange
 327                         operation.
 328   @param  CompareValue  Pointer value used in compare operation.
 329   @param  ExchangeValue Pointer value used in exchange operation.
 330
 331 **/
 332 VOID *
 333 EFIAPI
 334 InterlockedCompareExchangePointer (
 335   IN OUT  VOID                      **Value,
 336   IN      VOID                      *CompareValue,
 337   IN      VOID                      *ExchangeValue
 338   )
 339 {
 340   UINT8  SizeOfValue;
 341
 342   SizeOfValue = sizeof (*Value);
 343
 344   switch (SizeOfValue) {
 345     case sizeof (UINT32):
 346       return (VOID*)(UINTN)InterlockedCompareExchange32 (
 347                              (UINT32*)Value,
 348                              (UINT32)(UINTN)CompareValue,
 349                              (UINT32)(UINTN)ExchangeValue
 350                              );
 351     case sizeof (UINT64):
 352       return (VOID*)(UINTN)InterlockedCompareExchange64 (
 353                              (UINT64*)Value,
 354                              (UINT64)(UINTN)CompareValue,
 355                              (UINT64)(UINTN)ExchangeValue
 356                              );
 357     default:
 358       ASSERT (FALSE);
 359       return NULL;
 360   }
 361 }