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   Module Name:  Synchronization.c
  14
  15 **/
  16
  17 #define SPIN_LOCK_RELEASED          ((SPIN_LOCK)1)
  18 #define SPIN_LOCK_ACQUIRED          ((SPIN_LOCK)2)
  19
  20 UINT32
  21 EFIAPI
  22 InternalSyncIncrement (
  23   IN      volatile UINT32           *Value
  24   );
  25
  26 UINT32
  27 EFIAPI
  28 InternalSyncDecrement (
  29   IN      volatile UINT32           *Value
  30   );
  31
  32 UINT32
  33 EFIAPI
  34 InternalSyncCompareExchange32 (
  35   IN      volatile UINT32           *Value,
  36   IN      UINT32                    CompareValue,
  37   IN      UINT32                    ExchangeValue
  38   );
  39
  40 UINT64
  41 EFIAPI
  42 InternalSyncCompareExchange64 (
  43   IN      volatile UINT64           *Value,
  44   IN      UINT64                    CompareValue,
  45   IN      UINT64                    ExchangeValue
  46   );
  47
  48 /**
  49   Retrieves the architecture specific spin lock alignment requirements for
  50   optimal spin lock performance.
  51
  52   This function retrieves the spin lock alignment requirements for optimal
  53   performance on a given CPU architecture. The spin lock alignment must be a
  54   power of two and is returned by this function. If there are no alignment
  55   requirements, then 1 must be returned. The spin lock synchronization
  56   functions must function correctly if the spin lock size and alignment values
  57   returned by this function are not used at all. These values are hints to the
  58   consumers of the spin lock synchronization functions to obtain optimal spin
  59   lock performance.
  60
  61   @return The architecture specific spin lock alignment.
  62
  63 **/
  64 UINTN
  65 EFIAPI
  66 GetSpinLockProperties (
  67   VOID
  68   )
  69 {
  70   // @bug May use a PCD entry to determine this alignment.
  71   return 32;
  72 }
  73
  74 /**
  75   Initializes a spin lock to the released state and returns the spin lock.
  76
  77   This function initializes the spin lock specified by SpinLock to the released
  78   state, and returns SpinLock. Optimal performance can be achieved by calling
  79   GetSpinLockProperties() to determine the size and alignment requirements for
  80   SpinLock.
  81
  82   If SpinLock is NULL, then ASSERT().
  83
  84   @param  SpinLock  A pointer to the spin lock to initialize to the released
  85                     state.
  86
  87   @return SpinLock
  88
  89 **/
  90 SPIN_LOCK *
  91 EFIAPI
  92 InitializeSpinLock (
  93   OUT     SPIN_LOCK                 *SpinLock
  94   )
  95 {
  96   ASSERT (SpinLock != NULL);
  97   *SpinLock = SPIN_LOCK_RELEASED;
  98   return SpinLock;
  99 }
 100
 101 /**
 102   Waits until a spin lock can be placed in the acquired state.
 103
 104   This function checks the state of the spin lock specified by SpinLock. If
 105   SpinLock is in the released state, then this function places SpinLock in the
 106   acquired state and returns SpinLock. Otherwise, this function waits
 107   indefinitely for the spin lock to be released, and then places it in the
 108   acquired state and returns SpinLock. All state transitions of SpinLock must
 109   be performed using MP safe mechanisms.
 110
 111   If SpinLock is NULL, then ASSERT().
 112   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 113   If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in
 114   PcdSpinLockTimeout microseconds, then ASSERT().
 115
 116   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 117
 118   @return SpinLock
 119
 120 **/
 121 SPIN_LOCK *
 122 EFIAPI
 123 AcquireSpinLock (
 124   IN OUT  SPIN_LOCK                 *SpinLock
 125   )
 126 {
 127   UINT64                            Tick;
 128   UINT64                            Start, End;
 129   UINT64                            Timeout;
 130
 131   Tick = 0;
 132   Start = 0;
 133   End = 0;
 134   if (FixedPcdGet32 (PcdSpinLockTimeout) > 0) {
 135     Tick = GetPerformanceCounter ();
 136     Timeout = DivU64x32 (
 137                 MultU64x32 (
 138                   GetPerformanceCounterProperties (&Start, &End),
 139                   FixedPcdGet32 (PcdSpinLockTimeout)
 140                   ),
 141                 1000000
 142                 );
 143     if (Start < End) {
 144       Tick += Timeout;
 145     } else {
 146       Tick -= Timeout;
 147     }
 148   }
 149
 150   while (!AcquireSpinLockOrFail (SpinLock)) {
 151     CpuPause ();
 152     ASSERT ((Start < End) ^ (Tick <= GetPerformanceCounter ()));
 153   }
 154   return SpinLock;
 155 }
 156
 157 /**
 158   Attempts to place a spin lock in the acquired state.
 159
 160   This function checks the state of the spin lock specified by SpinLock. If
 161   SpinLock is in the released state, then this function places SpinLock in the
 162   acquired state and returns TRUE. Otherwise, FALSE is returned. All state
 163   transitions of SpinLock must be performed using MP safe mechanisms.
 164
 165   If SpinLock is NULL, then ASSERT().
 166   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 167
 168   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 169
 170   @retval TRUE  SpinLock was placed in the acquired state.
 171   @retval FALSE SpinLock could not be acquired.
 172
 173 **/
 174 BOOLEAN
 175 EFIAPI
 176 AcquireSpinLockOrFail (
 177   IN OUT  SPIN_LOCK                 *SpinLock
 178   )
 179 {
 180   ASSERT (SpinLock != NULL);
 181   ASSERT (*SpinLock == SPIN_LOCK_ACQUIRED || *SpinLock == SPIN_LOCK_RELEASED);
 182   return (BOOLEAN)(
 183            InterlockedCompareExchangePointer (
 184              (VOID**)SpinLock,
 185              (VOID*)SPIN_LOCK_RELEASED,
 186              (VOID*)SPIN_LOCK_ACQUIRED
 187              ) == (VOID*)SPIN_LOCK_RELEASED
 188            );
 189 }
 190
 191 /**
 192   Releases a spin lock.
 193
 194   This function places the spin lock specified by SpinLock in the release state
 195   and returns SpinLock.
 196
 197   If SpinLock is NULL, then ASSERT().
 198   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 199
 200   @param  SpinLock  A pointer to the spin lock to release.
 201
 202   @return SpinLock
 203
 204 **/
 205 SPIN_LOCK *
 206 EFIAPI
 207 ReleaseSpinLock (
 208   IN OUT  SPIN_LOCK                 *SpinLock
 209   )
 210 {
 211   ASSERT (SpinLock != NULL);
 212   ASSERT (*SpinLock == SPIN_LOCK_ACQUIRED || *SpinLock == SPIN_LOCK_RELEASED);
 213   *SpinLock = SPIN_LOCK_RELEASED;
 214   return SpinLock;
 215 }
 216
 217 /**
 218   Performs an atomic increment of an 32-bit unsigned integer.
 219
 220   Performs an atomic increment of the 32-bit unsigned integer specified by
 221   Value and returns the incremented value. The increment operation must be
 222   performed using MP safe mechanisms. The state of the return value is not
 223   guaranteed to be MP safe.
 224
 225   If Value is NULL, then ASSERT().
 226
 227   @param  Value A pointer to the 32-bit value to increment.
 228
 229   @return The incremented value.
 230
 231 **/
 232 UINT32
 233 EFIAPI
 234 InterlockedIncrement (
 235   IN      UINT32                    *Value
 236   )
 237 {
 238   ASSERT (Value != NULL);
 239   return InternalSyncIncrement (Value);
 240 }
 241
 242 /**
 243   Performs an atomic decrement of an 32-bit unsigned integer.
 244
 245   Performs an atomic decrement of the 32-bit unsigned integer specified by
 246   Value and returns the decremented value. The decrement operation must be
 247   performed using MP safe mechanisms. The state of the return value is not
 248   guaranteed to be MP safe.
 249
 250   If Value is NULL, then ASSERT().
 251
 252   @param  Value A pointer to the 32-bit value to decrement.
 253
 254   @return The decremented value.
 255
 256 **/
 257 UINT32
 258 EFIAPI
 259 InterlockedDecrement (
 260   IN      UINT32                    *Value
 261   )
 262 {
 263   ASSERT (Value != NULL);
 264   return InternalSyncDecrement (Value);
 265 }
 266
 267 /**
 268   Performs an atomic compare exchange operation on a 32-bit unsigned integer.
 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   @param  Value         A pointer to the 64-bit value for the compare exchange
 294                         operation.
 295   @param  CompareValue  64-bit value used in compare operation.
 296   @param  ExchangeValue 64-bit value used in exchange operation.
 297
 298   @return The original *Value before exchange.
 299
 300 **/
 301 UINT64
 302 EFIAPI
 303 InterlockedCompareExchange64 (
 304   IN OUT  UINT64                    *Value,
 305   IN      UINT64                    CompareValue,
 306   IN      UINT64                    ExchangeValue
 307   )
 308 {
 309   ASSERT (Value != NULL);
 310   return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);
 311 }
 312
 313 /**
 314   Performs an atomic compare exchange operation on a pointer value.
 315
 316   Performs an atomic compare exchange operation on the pointer value specified
 317   by Value. If Value is equal to CompareValue, then Value is set to
 318   ExchangeValue and CompareValue is returned. If Value is not equal to
 319   CompareValue, then Value is returned. The compare exchange operation must be
 320   performed using MP safe mechanisms.
 321
 322   If Value is NULL, then ASSERT().
 323
 324   @param  Value         A pointer to the pointer value for the compare exchange
 325                         operation.
 326   @param  CompareValue  Pointer value used in compare operation.
 327   @param  ExchangeValue Pointer value used in exchange operation.
 328
 329 **/
 330 VOID *
 331 EFIAPI
 332 InterlockedCompareExchangePointer (
 333   IN OUT  VOID                      **Value,
 334   IN      VOID                      *CompareValue,
 335   IN      VOID                      *ExchangeValue
 336   )
 337 {
 338   switch (sizeof (*Value)) {
 339     case sizeof (UINT32):
 340       return (VOID*)(UINTN)InterlockedCompareExchange32 (
 341                              (UINT32*)Value,
 342                              (UINT32)(UINTN)CompareValue,
 343                              (UINT32)(UINTN)ExchangeValue
 344                              );
 345     case sizeof (UINT64):
 346       return (VOID*)(UINTN)InterlockedCompareExchange64 (
 347                              (UINT64*)Value,
 348                              (UINT64)(UINTN)CompareValue,
 349                              (UINT64)(UINTN)ExchangeValue
 350                              );
 351     default:
 352       ASSERT (FALSE);
 353       return NULL;
 354   }
 355 }