MdePkg/Library/BaseSynchronizationLib/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 #include "BaseSynchronizationLibInternals.h"
  16
  17 //
  18 // GCC inline assembly for Read Write Barrier
  19 //
  20 #define _ReadWriteBarrier() do { asm volatile ("": : : "memory"); } while(0)
  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 in release state.
  64
  65 **/
  66 SPIN_LOCK *
  67 EFIAPI
  68 InitializeSpinLock (
  69   OUT      SPIN_LOCK                 *SpinLock
  70   )
  71 {
  72   ASSERT (SpinLock != NULL);
  73
  74   _ReadWriteBarrier();
  75   *SpinLock = SPIN_LOCK_RELEASED;
  76   _ReadWriteBarrier();
  77
  78   return SpinLock;
  79 }
  80
  81 /**
  82   Waits until a spin lock can be placed in the acquired state.
  83
  84   This function checks the state of the spin lock specified by SpinLock. If
  85   SpinLock is in the released state, then this function places SpinLock in the
  86   acquired state and returns SpinLock. Otherwise, this function waits
  87   indefinitely for the spin lock to be released, and then places it in the
  88   acquired state and returns SpinLock. All state transitions of SpinLock must
  89   be performed using MP safe mechanisms.
  90
  91   If SpinLock is NULL, then ASSERT().
  92   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
  93   If PcdSpinLockTimeout is not zero, and SpinLock is can not be acquired in
  94   PcdSpinLockTimeout microseconds, then ASSERT().
  95
  96   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
  97
  98   @return SpinLock acquired lock.
  99
 100 **/
 101 SPIN_LOCK *
 102 EFIAPI
 103 AcquireSpinLock (
 104   IN OUT  SPIN_LOCK                 *SpinLock
 105   )
 106 {
 107   UINT64  Current;
 108   UINT64  Previous;
 109   UINT64  Total;
 110   UINT64  Start;
 111   UINT64  End;
 112   UINT64  Timeout;
 113   INT64   Cycle;
 114   INT64   Delta;
 115
 116   if (PcdGet32 (PcdSpinLockTimeout) > 0) {
 117     //
 118     // Get the current timer value
 119     //
 120     Current = GetPerformanceCounter();
 121
 122     //
 123     // Initialize local variables
 124     //
 125     Start = 0;
 126     End   = 0;
 127     Total = 0;
 128
 129     //
 130     // Retrieve the performance counter properties and compute the number of performance
 131     // counter ticks required to reach the timeout
 132     //
 133     Timeout = DivU64x32 (
 134                 MultU64x32 (
 135                   GetPerformanceCounterProperties (&Start, &End),
 136                   PcdGet32 (PcdSpinLockTimeout)
 137                   ),
 138                 1000000
 139                 );
 140     Cycle = End - Start;
 141     if (Cycle < 0) {
 142       Cycle = -Cycle;
 143     }
 144     Cycle++;
 145
 146     while (!AcquireSpinLockOrFail (SpinLock)) {
 147       CpuPause ();
 148       Previous = Current;
 149       Current  = GetPerformanceCounter();
 150       Delta = (INT64) (Current - Previous);
 151       if (Start > End) {
 152         Delta = -Delta;
 153       }
 154       if (Delta < 0) {
 155         Delta += Cycle;
 156       }
 157       Total += Delta;
 158       ASSERT (Total < Timeout);
 159     }
 160   } else {
 161     while (!AcquireSpinLockOrFail (SpinLock)) {
 162       CpuPause ();
 163     }
 164   }
 165   return SpinLock;
 166 }
 167
 168 /**
 169   Attempts to place a spin lock in the acquired state.
 170
 171   This function checks the state of the spin lock specified by SpinLock. If
 172   SpinLock is in the released state, then this function places SpinLock in the
 173   acquired state and returns TRUE. Otherwise, FALSE is returned. All state
 174   transitions of SpinLock must be performed using MP safe mechanisms.
 175
 176   If SpinLock is NULL, then ASSERT().
 177   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 178
 179   @param  SpinLock  A pointer to the spin lock to place in the acquired state.
 180
 181   @retval TRUE  SpinLock was placed in the acquired state.
 182   @retval FALSE SpinLock could not be acquired.
 183
 184 **/
 185 BOOLEAN
 186 EFIAPI
 187 AcquireSpinLockOrFail (
 188   IN OUT  SPIN_LOCK                 *SpinLock
 189   )
 190 {
 191   SPIN_LOCK   LockValue;
 192   VOID        *Result;
 193
 194   ASSERT (SpinLock != NULL);
 195
 196   LockValue = *SpinLock;
 197   ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);
 198
 199   _ReadWriteBarrier ();
 200   Result = InterlockedCompareExchangePointer (
 201              (VOID**)SpinLock,
 202              (VOID*)SPIN_LOCK_RELEASED,
 203              (VOID*)SPIN_LOCK_ACQUIRED
 204            );
 205
 206   _ReadWriteBarrier ();
 207   return (BOOLEAN) (Result == (VOID*) SPIN_LOCK_RELEASED);
 208 }
 209
 210 /**
 211   Releases a spin lock.
 212
 213   This function places the spin lock specified by SpinLock in the release state
 214   and returns SpinLock.
 215
 216   If SpinLock is NULL, then ASSERT().
 217   If SpinLock was not initialized with InitializeSpinLock(), then ASSERT().
 218
 219   @param  SpinLock  A pointer to the spin lock to release.
 220
 221   @return SpinLock released lock.
 222
 223 **/
 224 SPIN_LOCK *
 225 EFIAPI
 226 ReleaseSpinLock (
 227   IN OUT  SPIN_LOCK                 *SpinLock
 228   )
 229 {
 230   SPIN_LOCK    LockValue;
 231
 232   ASSERT (SpinLock != NULL);
 233
 234   LockValue = *SpinLock;
 235   ASSERT (LockValue == SPIN_LOCK_ACQUIRED || LockValue == SPIN_LOCK_RELEASED);
 236
 237   _ReadWriteBarrier ();
 238   *SpinLock = SPIN_LOCK_RELEASED;
 239   _ReadWriteBarrier ();
 240
 241   return SpinLock;
 242 }
 243
 244 /**
 245   Performs an atomic increment of an 32-bit unsigned integer.
 246
 247   Performs an atomic increment of the 32-bit unsigned integer specified by
 248   Value and returns the incremented value. The increment operation must be
 249   performed using MP safe mechanisms. The state of the return value is not
 250   guaranteed to be MP safe.
 251
 252   If Value is NULL, then ASSERT().
 253
 254   @param  Value A pointer to the 32-bit value to increment.
 255
 256   @return The incremented value.
 257
 258 **/
 259 UINT32
 260 EFIAPI
 261 InterlockedIncrement (
 262   IN      UINT32                    *Value
 263   )
 264 {
 265   ASSERT (Value != NULL);
 266   return InternalSyncIncrement (Value);
 267 }
 268
 269 /**
 270   Performs an atomic decrement of an 32-bit unsigned integer.
 271
 272   Performs an atomic decrement of the 32-bit unsigned integer specified by
 273   Value and returns the decremented value. The decrement operation must be
 274   performed using MP safe mechanisms. The state of the return value is not
 275   guaranteed to be MP safe.
 276
 277   If Value is NULL, then ASSERT().
 278
 279   @param  Value A pointer to the 32-bit value to decrement.
 280
 281   @return The decremented value.
 282
 283 **/
 284 UINT32
 285 EFIAPI
 286 InterlockedDecrement (
 287   IN      UINT32                    *Value
 288   )
 289 {
 290   ASSERT (Value != NULL);
 291   return InternalSyncDecrement (Value);
 292 }
 293
 294 /**
 295   Performs an atomic compare exchange operation on a 32-bit unsigned integer.
 296
 297   Performs an atomic compare exchange operation on the 32-bit unsigned integer
 298   specified by Value.  If Value is equal to CompareValue, then Value is set to
 299   ExchangeValue and CompareValue is returned.  If Value is not equal to CompareValue,
 300   then Value is returned.  The compare exchange operation must be performed using
 301   MP safe mechanisms.
 302
 303   If Value is NULL, then ASSERT().
 304
 305   @param  Value         A pointer to the 32-bit value for the compare exchange
 306                         operation.
 307   @param  CompareValue  32-bit value used in compare operation.
 308   @param  ExchangeValue 32-bit value used in exchange operation.
 309
 310   @return The original *Value before exchange.
 311
 312 **/
 313 UINT32
 314 EFIAPI
 315 InterlockedCompareExchange32 (
 316   IN OUT  UINT32                    *Value,
 317   IN      UINT32                    CompareValue,
 318   IN      UINT32                    ExchangeValue
 319   )
 320 {
 321   ASSERT (Value != NULL);
 322   return InternalSyncCompareExchange32 (Value, CompareValue, ExchangeValue);
 323 }
 324
 325 /**
 326   Performs an atomic compare exchange operation on a 64-bit unsigned integer.
 327
 328   Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
 329   by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
 330   CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
 331   The compare exchange operation must be performed using MP safe mechanisms.
 332
 333   If Value is NULL, then ASSERT().
 334
 335   @param  Value         A pointer to the 64-bit value for the compare exchange
 336                         operation.
 337   @param  CompareValue  64-bit value used in compare operation.
 338   @param  ExchangeValue 64-bit value used in exchange operation.
 339
 340   @return The original *Value before exchange.
 341
 342 **/
 343 UINT64
 344 EFIAPI
 345 InterlockedCompareExchange64 (
 346   IN OUT  UINT64                    *Value,
 347   IN      UINT64                    CompareValue,
 348   IN      UINT64                    ExchangeValue
 349   )
 350 {
 351   ASSERT (Value != NULL);
 352   return InternalSyncCompareExchange64 (Value, CompareValue, ExchangeValue);
 353 }
 354
 355 /**
 356   Performs an atomic compare exchange operation on a pointer value.
 357
 358   Performs an atomic compare exchange operation on the pointer value specified
 359   by Value. If Value is equal to CompareValue, then Value is set to
 360   ExchangeValue and CompareValue is returned. If Value is not equal to
 361   CompareValue, then Value is returned. The compare exchange operation must be
 362   performed using MP safe mechanisms.
 363
 364   If Value is NULL, then ASSERT().
 365
 366   @param  Value         A pointer to the pointer value for the compare exchange
 367                         operation.
 368   @param  CompareValue  Pointer value used in compare operation.
 369   @param  ExchangeValue Pointer value used in exchange operation.
 370
 371   @return The original *Value before exchange.
 372 **/
 373 VOID *
 374 EFIAPI
 375 InterlockedCompareExchangePointer (
 376   IN OUT  VOID                      **Value,
 377   IN      VOID                      *CompareValue,
 378   IN      VOID                      *ExchangeValue
 379   )
 380 {
 381   UINT8  SizeOfValue;
 382
 383   SizeOfValue = sizeof (*Value);
 384
 385   switch (SizeOfValue) {
 386     case sizeof (UINT32):
 387       return (VOID*)(UINTN)InterlockedCompareExchange32 (
 388                              (UINT32*)Value,
 389                              (UINT32)(UINTN)CompareValue,
 390                              (UINT32)(UINTN)ExchangeValue
 391                              );
 392     case sizeof (UINT64):
 393       return (VOID*)(UINTN)InterlockedCompareExchange64 (
 394                              (UINT64*)Value,
 395                              (UINT64)(UINTN)CompareValue,
 396                              (UINT64)(UINTN)ExchangeValue
 397                              );
 398     default:
 399       ASSERT (FALSE);
 400       return NULL;
 401   }
 402 }