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 #include "BaseLibInternals.h"
  16
  17 #define SPIN_LOCK_RELEASED          ((UINTN) 1)
  18 #define SPIN_LOCK_ACQUIRED          ((UINTN) 2)
  19
  20 /**
  21   Retrieves the architecture specific spin lock alignment requirements for
  22   optimal spin lock performance.
  23
  24   This function retrieves the spin lock alignment requirements for optimal
  25   performance on a given CPU architecture. The spin lock alignment must be a
  26   power of two and is returned by this function. If there are no alignment
  27   requirements, then 1 must be returned. The spin lock synchronization
  28   functions must function correctly if the spin lock size and alignment values
  29   returned by this function are not used at all. These values are hints to the
  30   consumers of the spin lock synchronization functions to obtain optimal spin
  31   lock performance.
  32
  33   @return The architecture specific spin lock alignment.
  34
  35 **/
  36 UINTN
  37 EFIAPI
  38 GetSpinLockProperties (
  39   VOID
  40   )
  41 {
  42   return 32;
  43 }
  44
  45 /**
  46   Initializes a spin lock to the released state and returns the spin lock.
  47
  48   This function initializes the spin lock specified by SpinLock to the released
  49   state, and returns SpinLock. Optimal performance can be achieved by calling
  50   GetSpinLockProperties() to determine the size and alignment requirements for
  51   SpinLock.
  52
  53   If SpinLock is NULL, then ASSERT().
  54
  55   @param  SpinLock  A pointer to the spin lock to initialize to the released
  56                     state.
  57
  58   @return SpinLock in release state.
  59
  60 **/
  61 SPIN_LOCK *
  62 EFIAPI
  63 InitializeSpinLock (
  64   OUT     SPIN_LOCK                 *SpinLock
  65   )
  66 {
  67   ASSERT (SpinLock != NULL);
  68   *SpinLock = SPIN_LOCK_RELEASED;
  69   return SpinLock;
  70 }
  71
  72 /**
  73   Waits until a spin lock can be placed in the acquired state.
  74
  75   This function checks the state of the spin lock specified by SpinLock. If
  76   SpinLock is in the released state, then this function places SpinLock in the
  77   acquired state and returns SpinLock. Otherwise, this function waits
  78   indefinitely for the spin lock to be released, and then places it in the
  79   acquired state and returns SpinLock. All state transitions of SpinLock must
  80   be performed using MP safe mechanisms.
  81
  82   If SpinLock is NULL, then ASSERT().
  83   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
  84   If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in
  85   PcdSpinLockTimeout microseconds, then ASSERT().
  86
  87   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
  88
  89   @return SpinLock acquired lock.
  90
  91 **/
  92 SPIN_LOCK *
  93 EFIAPI
  94 AcquireSpinLock (
  95   IN OUT  SPIN_LOCK                 *SpinLock
  96   )
  97 {
  98   UINT64  Current;
  99   UINT64  Previous;
 100   UINT64  Total;
 101   UINT64  Start;
 102   UINT64  End;
 103   UINT64  Timeout;
 104   INT64   Cycle;
 105   INT64   Delta;
 106
 107   if (PcdGet32 (PcdSpinLockTimeout) > 0) {
 108     //
 109     // Get the current timer value
 110     //
 111     Current = GetPerformanceCounter();
 112
 113     //
 114     // Initialize local variables
 115     //
 116     Start = 0;
 117     End   = 0;
 118     Total = 0;
 119
 120     //
 121     // Retrieve the performance counter properties and compute the number of performance
 122     // counter ticks required to reach the timeout
 123     //
 124     Timeout = DivU64x32 (
 125                 MultU64x32 (
 126                   GetPerformanceCounterProperties (&Start, &End),
 127                   PcdGet32 (PcdSpinLockTimeout)
 128                   ),
 129                 1000000
 130                 );
 131     Cycle = End - Start;
 132     if (Cycle < 0) {
 133       Cycle = -Cycle;
 134     }
 135     Cycle++;
 136
 137     while (!AcquireSpinLockOrFail (SpinLock)) {
 138       CpuPause ();
 139       Previous = Current;
 140       Current  = GetPerformanceCounter();
 141       Delta = (INT64) (Current - Previous);
 142       if (Start > End) {
 143         Delta = -Delta;
 144       }
 145       if (Delta < 0) {
 146         Delta += Cycle;
 147       }
 148       Total += Delta;
 149       ASSERT (Total < Timeout);
 150     }
 151   } else {
 152     while (!AcquireSpinLockOrFail (SpinLock)) {
 153       CpuPause ();
 154     }
 155   }
 156   return SpinLock;
 157 }
 158
 159 /**
 160   Attempts to place a spin lock in the acquired state.
 161
 162   This function checks the state of the spin lock specified by SpinLock. If
 163   SpinLock is in the released state, then this function places SpinLock in the
 164   acquired state and returns TRUE. Otherwise, FALSE is returned. All state
 165   transitions of SpinLock must be performed using MP safe mechanisms.
 166
 167   If SpinLock is NULL, then ASSERT().
 168   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 169
 170   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 171
 172   @retval TRUE  SpinLock was placed in the acquired state.
 173   @retval FALSE SpinLock could not be acquired.
 174
 175 **/
 176 BOOLEAN
 177 EFIAPI
 178 AcquireSpinLockOrFail (
 179   IN OUT  SPIN_LOCK                 *SpinLock
 180   )
 181 {
 182   SPIN_LOCK    LockValue;
 183
 184   ASSERT (SpinLock != NULL);
 185
 186   LockValue = *SpinLock;
 187   ASSERT (SPIN_LOCK_ACQUIRED == LockValue || SPIN_LOCK_RELEASED == LockValue);
 188
 189   return (BOOLEAN)(
 190            InterlockedCompareExchangePointer (
 191              (VOID**)SpinLock,
 192              (VOID*)SPIN_LOCK_RELEASED,
 193              (VOID*)SPIN_LOCK_ACQUIRED
 194              ) == (VOID*)SPIN_LOCK_RELEASED
 195            );
 196 }
 197
 198 /**
 199   Releases a spin lock.
 200
 201   This function places the spin lock specified by SpinLock in the release state
 202   and returns SpinLock.
 203
 204   If SpinLock is NULL, then ASSERT().
 205   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 206
 207   @param  SpinLock  A pointer to the spin lock to release.
 208
 209   @return SpinLock released lock.
 210
 211 **/
 212 SPIN_LOCK *
 213 EFIAPI
 214 ReleaseSpinLock (
 215   IN OUT  SPIN_LOCK                 *SpinLock
 216   )
 217 {
 218   SPIN_LOCK    LockValue;
 219
 220   ASSERT (SpinLock != NULL);
 221
 222   LockValue = *SpinLock;
 223   ASSERT (SPIN_LOCK_ACQUIRED == LockValue || SPIN_LOCK_RELEASED == LockValue);
 224
 225   *SpinLock = SPIN_LOCK_RELEASED;
 226   return SpinLock;
 227 }
 228
 229 /**
 230   Performs an atomic increment of an 32-bit unsigned integer.
 231
 232   Performs an atomic increment of the 32-bit unsigned integer specified by
 233   Value and returns the incremented value. The increment 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 increment.
 240
 241   @return The incremented value.
 242
 243 **/
 244 UINT32
 245 EFIAPI
 246 InterlockedIncrement (
 247   IN      UINT32                    *Value
 248   )
 249 {
 250   ASSERT (Value != NULL);
 251   return InternalSyncIncrement (Value);
 252 }
 253
 254 /**
 255   Performs an atomic decrement of an 32-bit unsigned integer.
 256
 257   Performs an atomic decrement of the 32-bit unsigned integer specified by
 258   Value and returns the decremented value. The decrement operation must be
 259   performed using MP safe mechanisms. The state of the return value is not
 260   guaranteed to be MP safe.
 261
 262   If Value is NULL, then ASSERT().
 263
 264   @param  Value A pointer to the 32-bit value to decrement.
 265
 266   @return The decremented value.
 267
 268 **/
 269 UINT32
 270 EFIAPI
 271 InterlockedDecrement (
 272   IN      UINT32                    *Value
 273   )
 274 {
 275   ASSERT (Value != NULL);
 276   return InternalSyncDecrement (Value);
 277 }
 278
 279 /**
 280   Performs an atomic compare exchange operation on a 32-bit unsigned integer.
 281
 282   Performs an atomic compare exchange operation on the 32-bit unsigned integer
 283   specified by Value.  If Value is equal to CompareValue, then Value is set to
 284   ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
 285   then Value is returned.  The compare exchange operation must be performed using
 286   MP safe mechanisms.
 287
 288   If Value is NULL, then ASSERT().
 289
 290   @param  Value         A pointer to the 32-bit value for the compare exchange
 291                         operation.
 292   @param  CompareValue  32-bit value used in compare operation.
 293   @param  ExchangeValue 32-bit value used in exchange operation.
 294
 295   @return The original *Value before exchange.
 296
 297 **/
 298 UINT32
 299 EFIAPI
 300 InterlockedCompareExchange32 (
 301   IN OUT  UINT32                    *Value,
 302   IN      UINT32                    CompareValue,
 303   IN      UINT32                    ExchangeValue
 304   )
 305 {
 306   ASSERT (Value != NULL);
 307   return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);
 308 }
 309
 310 /**
 311   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
 312
 313   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
 314   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
 315   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
 316   The compare exchange operation must be performed using MP safe mechanisms.
 317
 318   If Value is NULL, then ASSERT().
 319
 320   @param  Value         A pointer to the 64-bit value for the compare exchange
 321                         operation.
 322   @param  CompareValue  64-bit value used in compare operation.
 323   @param  ExchangeValue 64-bit value used in exchange operation.
 324
 325   @return The original *Value before exchange.
 326
 327 **/
 328 UINT64
 329 EFIAPI
 330 InterlockedCompareExchange64 (
 331   IN OUT  UINT64                    *Value,
 332   IN      UINT64                    CompareValue,
 333   IN      UINT64                    ExchangeValue
 334   )
 335 {
 336   ASSERT (Value != NULL);
 337   return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);
 338 }
 339
 340 /**
 341   Performs an atomic compare exchange operation on a pointer value.
 342
 343   Performs an atomic compare exchange operation on the pointer value specified
 344   by Value. If Value is equal to CompareValue, then Value is set to
 345   ExchangeValue and CompareValue is returned. If Value is not equal to
 346   CompareValue, then Value is returned. The compare exchange operation must be
 347   performed using MP safe mechanisms.
 348
 349   If Value is NULL, then ASSERT().
 350
 351   @param  Value         A pointer to the pointer value for the compare exchange
 352                         operation.
 353   @param  CompareValue  Pointer value used in compare operation.
 354   @param  ExchangeValue Pointer value used in exchange operation.
 355
 356   @return The original *Value before exchange.
 357
 358 **/
 359 VOID *
 360 EFIAPI
 361 InterlockedCompareExchangePointer (
 362   IN OUT  VOID                      **Value,
 363   IN      VOID                      *CompareValue,
 364   IN      VOID                      *ExchangeValue
 365   )
 366 {
 367   UINT8  SizeOfValue;
 368
 369   SizeOfValue = sizeof (*Value);
 370
 371   switch (SizeOfValue) {
 372     case sizeof (UINT32):
 373       return (VOID*)(UINTN)InterlockedCompareExchange32 (
 374                              (UINT32*)Value,
 375                              (UINT32)(UINTN)CompareValue,
 376                              (UINT32)(UINTN)ExchangeValue
 377                              );
 378     case sizeof (UINT64):
 379       return (VOID*)(UINTN)InterlockedCompareExchange64 (
 380                              (UINT64*)Value,
 381                              (UINT64)(UINTN)CompareValue,
 382                              (UINT64)(UINTN)ExchangeValue
 383                              );
 384     default:
 385       ASSERT (FALSE);
 386       return NULL;
 387   }
 388 }