reactos/drivers/bus/acpi/acpica/parser/psparse.c

   1 /******************************************************************************
   2  *
   3  * Module Name: psparse - Parser top level AML parse routines
   4  *
   5  *****************************************************************************/
   6
   7 /******************************************************************************
   8  *
   9  * 1. Copyright Notice
  10  *
  11  * Some or all of this work - Copyright (c) 1999 - 2011, Intel Corp.
  12  * All rights reserved.
  13  *
  14  * 2. License
  15  *
  16  * 2.1. This is your license from Intel Corp. under its intellectual property
  17  * rights.  You may have additional license terms from the party that provided
  18  * you this software, covering your right to use that party's intellectual
  19  * property rights.
  20  *
  21  * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
  22  * copy of the source code appearing in this file ("Covered Code") an
  23  * irrevocable, perpetual, worldwide license under Intel's copyrights in the
  24  * base code distributed originally by Intel ("Original Intel Code") to copy,
  25  * make derivatives, distribute, use and display any portion of the Covered
  26  * Code in any form, with the right to sublicense such rights; and
  27  *
  28  * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
  29  * license (with the right to sublicense), under only those claims of Intel
  30  * patents that are infringed by the Original Intel Code, to make, use, sell,
  31  * offer to sell, and import the Covered Code and derivative works thereof
  32  * solely to the minimum extent necessary to exercise the above copyright
  33  * license, and in no event shall the patent license extend to any additions
  34  * to or modifications of the Original Intel Code.  No other license or right
  35  * is granted directly or by implication, estoppel or otherwise;
  36  *
  37  * The above copyright and patent license is granted only if the following
  38  * conditions are met:
  39  *
  40  * 3. Conditions
  41  *
  42  * 3.1. Redistribution of Source with Rights to Further Distribute Source.
  43  * Redistribution of source code of any substantial portion of the Covered
  44  * Code or modification with rights to further distribute source must include
  45  * the above Copyright Notice, the above License, this list of Conditions,
  46  * and the following Disclaimer and Export Compliance provision.  In addition,
  47  * Licensee must cause all Covered Code to which Licensee contributes to
  48  * contain a file documenting the changes Licensee made to create that Covered
  49  * Code and the date of any change.  Licensee must include in that file the
  50  * documentation of any changes made by any predecessor Licensee.  Licensee
  51  * must include a prominent statement that the modification is derived,
  52  * directly or indirectly, from Original Intel Code.
  53  *
  54  * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
  55  * Redistribution of source code of any substantial portion of the Covered
  56  * Code or modification without rights to further distribute source must
  57  * include the following Disclaimer and Export Compliance provision in the
  58  * documentation and/or other materials provided with distribution.  In
  59  * addition, Licensee may not authorize further sublicense of source of any
  60  * portion of the Covered Code, and must include terms to the effect that the
  61  * license from Licensee to its licensee is limited to the intellectual
  62  * property embodied in the software Licensee provides to its licensee, and
  63  * not to intellectual property embodied in modifications its licensee may
  64  * make.
  65  *
  66  * 3.3. Redistribution of Executable. Redistribution in executable form of any
  67  * substantial portion of the Covered Code or modification must reproduce the
  68  * above Copyright Notice, and the following Disclaimer and Export Compliance
  69  * provision in the documentation and/or other materials provided with the
  70  * distribution.
  71  *
  72  * 3.4. Intel retains all right, title, and interest in and to the Original
  73  * Intel Code.
  74  *
  75  * 3.5. Neither the name Intel nor any other trademark owned or controlled by
  76  * Intel shall be used in advertising or otherwise to promote the sale, use or
  77  * other dealings in products derived from or relating to the Covered Code
  78  * without prior written authorization from Intel.
  79  *
  80  * 4. Disclaimer and Export Compliance
  81  *
  82  * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
  83  * HERE.  ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
  84  * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT,  ASSISTANCE,
  85  * INSTALLATION, TRAINING OR OTHER SERVICES.  INTEL WILL NOT PROVIDE ANY
  86  * UPDATES, ENHANCEMENTS OR EXTENSIONS.  INTEL SPECIFICALLY DISCLAIMS ANY
  87  * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
  88  * PARTICULAR PURPOSE.
  89  *
  90  * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
  91  * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
  92  * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
  93  * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
  94  * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
  95  * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES.  THESE LIMITATIONS
  96  * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
  97  * LIMITED REMEDY.
  98  *
  99  * 4.3. Licensee shall not export, either directly or indirectly, any of this
 100  * software or system incorporating such software without first obtaining any
 101  * required license or other approval from the U. S. Department of Commerce or
 102  * any other agency or department of the United States Government.  In the
 103  * event Licensee exports any such software from the United States or
 104  * re-exports any such software from a foreign destination, Licensee shall
 105  * ensure that the distribution and export/re-export of the software is in
 106  * compliance with all laws, regulations, orders, or other restrictions of the
 107  * U.S. Export Administration Regulations. Licensee agrees that neither it nor
 108  * any of its subsidiaries will export/re-export any technical data, process,
 109  * software, or service, directly or indirectly, to any country for which the
 110  * United States government or any agency thereof requires an export license,
 111  * other governmental approval, or letter of assurance, without first obtaining
 112  * such license, approval or letter.
 113  *
 114  *****************************************************************************/
 115
 116
 117 /*
 118  * Parse the AML and build an operation tree as most interpreters,
 119  * like Perl, do.  Parsing is done by hand rather than with a YACC
 120  * generated parser to tightly constrain stack and dynamic memory
 121  * usage.  At the same time, parsing is kept flexible and the code
 122  * fairly compact by parsing based on a list of AML opcode
 123  * templates in AmlOpInfo[]
 124  */
 125
 126 #include "acpi.h"
 127 #include "accommon.h"
 128 #include "acparser.h"
 129 #include "acdispat.h"
 130 #include "amlcode.h"
 131 #include "acinterp.h"
 132
 133 #define _COMPONENT          ACPI_PARSER
 134         ACPI_MODULE_NAME    ("psparse")
 135
 136
 137 /*******************************************************************************
 138  *
 139  * FUNCTION:    AcpiPsGetOpcodeSize
 140  *
 141  * PARAMETERS:  Opcode          - An AML opcode
 142  *
 143  * RETURN:      Size of the opcode, in bytes (1 or 2)
 144  *
 145  * DESCRIPTION: Get the size of the current opcode.
 146  *
 147  ******************************************************************************/
 148
 149 UINT32
 150 AcpiPsGetOpcodeSize (
 151     UINT32                  Opcode)
 152 {
 153
 154     /* Extended (2-byte) opcode if > 255 */
 155
 156     if (Opcode > 0x00FF)
 157     {
 158         return (2);
 159     }
 160
 161     /* Otherwise, just a single byte opcode */
 162
 163     return (1);
 164 }
 165
 166
 167 /*******************************************************************************
 168  *
 169  * FUNCTION:    AcpiPsPeekOpcode
 170  *
 171  * PARAMETERS:  ParserState         - A parser state object
 172  *
 173  * RETURN:      Next AML opcode
 174  *
 175  * DESCRIPTION: Get next AML opcode (without incrementing AML pointer)
 176  *
 177  ******************************************************************************/
 178
 179 UINT16
 180 AcpiPsPeekOpcode (
 181     ACPI_PARSE_STATE        *ParserState)
 182 {
 183     UINT8                   *Aml;
 184     UINT16                  Opcode;
 185
 186
 187     Aml = ParserState->Aml;
 188     Opcode = (UINT16) ACPI_GET8 (Aml);
 189
 190     if (Opcode == AML_EXTENDED_OP_PREFIX)
 191     {
 192         /* Extended opcode, get the second opcode byte */
 193
 194         Aml++;
 195         Opcode = (UINT16) ((Opcode << 8) | ACPI_GET8 (Aml));
 196     }
 197
 198     return (Opcode);
 199 }
 200
 201
 202 /*******************************************************************************
 203  *
 204  * FUNCTION:    AcpiPsCompleteThisOp
 205  *
 206  * PARAMETERS:  WalkState       - Current State
 207  *              Op              - Op to complete
 208  *
 209  * RETURN:      Status
 210  *
 211  * DESCRIPTION: Perform any cleanup at the completion of an Op.
 212  *
 213  ******************************************************************************/
 214
 215 ACPI_STATUS
 216 AcpiPsCompleteThisOp (
 217     ACPI_WALK_STATE         *WalkState,
 218     ACPI_PARSE_OBJECT       *Op)
 219 {
 220     ACPI_PARSE_OBJECT       *Prev;
 221     ACPI_PARSE_OBJECT       *Next;
 222     const ACPI_OPCODE_INFO  *ParentInfo;
 223     ACPI_PARSE_OBJECT       *ReplacementOp = NULL;
 224     ACPI_STATUS             Status = AE_OK;
 225
 226
 227     ACPI_FUNCTION_TRACE_PTR (PsCompleteThisOp, Op);
 228
 229
 230     /* Check for null Op, can happen if AML code is corrupt */
 231
 232     if (!Op)
 233     {
 234         return_ACPI_STATUS (AE_OK);  /* OK for now */
 235     }
 236
 237     /* Delete this op and the subtree below it if asked to */
 238
 239     if (((WalkState->ParseFlags & ACPI_PARSE_TREE_MASK) != ACPI_PARSE_DELETE_TREE) ||
 240          (WalkState->OpInfo->Class == AML_CLASS_ARGUMENT))
 241     {
 242         return_ACPI_STATUS (AE_OK);
 243     }
 244
 245     /* Make sure that we only delete this subtree */
 246
 247     if (Op->Common.Parent)
 248     {
 249         Prev = Op->Common.Parent->Common.Value.Arg;
 250         if (!Prev)
 251         {
 252             /* Nothing more to do */
 253
 254             goto Cleanup;
 255         }
 256
 257         /*
 258          * Check if we need to replace the operator and its subtree
 259          * with a return value op (placeholder op)
 260          */
 261         ParentInfo = AcpiPsGetOpcodeInfo (Op->Common.Parent->Common.AmlOpcode);
 262
 263         switch (ParentInfo->Class)
 264         {
 265         case AML_CLASS_CONTROL:
 266             break;
 267
 268         case AML_CLASS_CREATE:
 269
 270             /*
 271              * These opcodes contain TermArg operands.  The current
 272              * op must be replaced by a placeholder return op
 273              */
 274             ReplacementOp = AcpiPsAllocOp (AML_INT_RETURN_VALUE_OP);
 275             if (!ReplacementOp)
 276             {
 277                 Status = AE_NO_MEMORY;
 278             }
 279             break;
 280
 281         case AML_CLASS_NAMED_OBJECT:
 282
 283             /*
 284              * These opcodes contain TermArg operands.  The current
 285              * op must be replaced by a placeholder return op
 286              */
 287             if ((Op->Common.Parent->Common.AmlOpcode == AML_REGION_OP)       ||
 288                 (Op->Common.Parent->Common.AmlOpcode == AML_DATA_REGION_OP)  ||
 289                 (Op->Common.Parent->Common.AmlOpcode == AML_BUFFER_OP)       ||
 290                 (Op->Common.Parent->Common.AmlOpcode == AML_PACKAGE_OP)      ||
 291                 (Op->Common.Parent->Common.AmlOpcode == AML_BANK_FIELD_OP)   ||
 292                 (Op->Common.Parent->Common.AmlOpcode == AML_VAR_PACKAGE_OP))
 293             {
 294                 ReplacementOp = AcpiPsAllocOp (AML_INT_RETURN_VALUE_OP);
 295                 if (!ReplacementOp)
 296                 {
 297                     Status = AE_NO_MEMORY;
 298                 }
 299             }
 300             else if ((Op->Common.Parent->Common.AmlOpcode == AML_NAME_OP) &&
 301                      (WalkState->PassNumber <= ACPI_IMODE_LOAD_PASS2))
 302             {
 303                 if ((Op->Common.AmlOpcode == AML_BUFFER_OP) ||
 304                     (Op->Common.AmlOpcode == AML_PACKAGE_OP) ||
 305                     (Op->Common.AmlOpcode == AML_VAR_PACKAGE_OP))
 306                 {
 307                     ReplacementOp = AcpiPsAllocOp (Op->Common.AmlOpcode);
 308                     if (!ReplacementOp)
 309                     {
 310                         Status = AE_NO_MEMORY;
 311                     }
 312                     else
 313                     {
 314                         ReplacementOp->Named.Data = Op->Named.Data;
 315                         ReplacementOp->Named.Length = Op->Named.Length;
 316                     }
 317                 }
 318             }
 319             break;
 320
 321         default:
 322
 323             ReplacementOp = AcpiPsAllocOp (AML_INT_RETURN_VALUE_OP);
 324             if (!ReplacementOp)
 325             {
 326                 Status = AE_NO_MEMORY;
 327             }
 328         }
 329
 330         /* We must unlink this op from the parent tree */
 331
 332         if (Prev == Op)
 333         {
 334             /* This op is the first in the list */
 335
 336             if (ReplacementOp)
 337             {
 338                 ReplacementOp->Common.Parent        = Op->Common.Parent;
 339                 ReplacementOp->Common.Value.Arg     = NULL;
 340                 ReplacementOp->Common.Node          = Op->Common.Node;
 341                 Op->Common.Parent->Common.Value.Arg = ReplacementOp;
 342                 ReplacementOp->Common.Next          = Op->Common.Next;
 343             }
 344             else
 345             {
 346                 Op->Common.Parent->Common.Value.Arg = Op->Common.Next;
 347             }
 348         }
 349
 350         /* Search the parent list */
 351
 352         else while (Prev)
 353         {
 354             /* Traverse all siblings in the parent's argument list */
 355
 356             Next = Prev->Common.Next;
 357             if (Next == Op)
 358             {
 359                 if (ReplacementOp)
 360                 {
 361                     ReplacementOp->Common.Parent    = Op->Common.Parent;
 362                     ReplacementOp->Common.Value.Arg = NULL;
 363                     ReplacementOp->Common.Node      = Op->Common.Node;
 364                     Prev->Common.Next               = ReplacementOp;
 365                     ReplacementOp->Common.Next      = Op->Common.Next;
 366                     Next = NULL;
 367                 }
 368                 else
 369                 {
 370                     Prev->Common.Next = Op->Common.Next;
 371                     Next = NULL;
 372                 }
 373             }
 374             Prev = Next;
 375         }
 376     }
 377
 378
 379 Cleanup:
 380
 381     /* Now we can actually delete the subtree rooted at Op */
 382
 383     AcpiPsDeleteParseTree (Op);
 384     return_ACPI_STATUS (Status);
 385 }
 386
 387
 388 /*******************************************************************************
 389  *
 390  * FUNCTION:    AcpiPsNextParseState
 391  *
 392  * PARAMETERS:  WalkState           - Current state
 393  *              Op                  - Current parse op
 394  *              CallbackStatus      - Status from previous operation
 395  *
 396  * RETURN:      Status
 397  *
 398  * DESCRIPTION: Update the parser state based upon the return exception from
 399  *              the parser callback.
 400  *
 401  ******************************************************************************/
 402
 403 ACPI_STATUS
 404 AcpiPsNextParseState (
 405     ACPI_WALK_STATE         *WalkState,
 406     ACPI_PARSE_OBJECT       *Op,
 407     ACPI_STATUS             CallbackStatus)
 408 {
 409     ACPI_PARSE_STATE        *ParserState = &WalkState->ParserState;
 410     ACPI_STATUS             Status = AE_CTRL_PENDING;
 411
 412
 413     ACPI_FUNCTION_TRACE_PTR (PsNextParseState, Op);
 414
 415
 416     switch (CallbackStatus)
 417     {
 418     case AE_CTRL_TERMINATE:
 419         /*
 420          * A control method was terminated via a RETURN statement.
 421          * The walk of this method is complete.
 422          */
 423         ParserState->Aml = ParserState->AmlEnd;
 424         Status = AE_CTRL_TERMINATE;
 425         break;
 426
 427
 428     case AE_CTRL_BREAK:
 429
 430         ParserState->Aml = WalkState->AmlLastWhile;
 431         WalkState->ControlState->Common.Value = FALSE;
 432         Status = AE_CTRL_BREAK;
 433         break;
 434
 435
 436     case AE_CTRL_CONTINUE:
 437
 438         ParserState->Aml = WalkState->AmlLastWhile;
 439         Status = AE_CTRL_CONTINUE;
 440         break;
 441
 442
 443     case AE_CTRL_PENDING:
 444
 445         ParserState->Aml = WalkState->AmlLastWhile;
 446         break;
 447
 448 #if 0
 449     case AE_CTRL_SKIP:
 450
 451         ParserState->Aml = ParserState->Scope->ParseScope.PkgEnd;
 452         Status = AE_OK;
 453         break;
 454 #endif
 455
 456     case AE_CTRL_TRUE:
 457         /*
 458          * Predicate of an IF was true, and we are at the matching ELSE.
 459          * Just close out this package
 460          */
 461         ParserState->Aml = AcpiPsGetNextPackageEnd (ParserState);
 462         Status = AE_CTRL_PENDING;
 463         break;
 464
 465
 466     case AE_CTRL_FALSE:
 467         /*
 468          * Either an IF/WHILE Predicate was false or we encountered a BREAK
 469          * opcode.  In both cases, we do not execute the rest of the
 470          * package;  We simply close out the parent (finishing the walk of
 471          * this branch of the tree) and continue execution at the parent
 472          * level.
 473          */
 474         ParserState->Aml = ParserState->Scope->ParseScope.PkgEnd;
 475
 476         /* In the case of a BREAK, just force a predicate (if any) to FALSE */
 477
 478         WalkState->ControlState->Common.Value = FALSE;
 479         Status = AE_CTRL_END;
 480         break;
 481
 482
 483     case AE_CTRL_TRANSFER:
 484
 485         /* A method call (invocation) -- transfer control */
 486
 487         Status = AE_CTRL_TRANSFER;
 488         WalkState->PrevOp = Op;
 489         WalkState->MethodCallOp = Op;
 490         WalkState->MethodCallNode = (Op->Common.Value.Arg)->Common.Node;
 491
 492         /* Will return value (if any) be used by the caller? */
 493
 494         WalkState->ReturnUsed = AcpiDsIsResultUsed (Op, WalkState);
 495         break;
 496
 497
 498     default:
 499
 500         Status = CallbackStatus;
 501         if ((CallbackStatus & AE_CODE_MASK) == AE_CODE_CONTROL)
 502         {
 503             Status = AE_OK;
 504         }
 505         break;
 506     }
 507
 508     return_ACPI_STATUS (Status);
 509 }
 510
 511
 512 /*******************************************************************************
 513  *
 514  * FUNCTION:    AcpiPsParseAml
 515  *
 516  * PARAMETERS:  WalkState       - Current state
 517  *
 518  *
 519  * RETURN:      Status
 520  *
 521  * DESCRIPTION: Parse raw AML and return a tree of ops
 522  *
 523  ******************************************************************************/
 524
 525 ACPI_STATUS
 526 AcpiPsParseAml (
 527     ACPI_WALK_STATE         *WalkState)
 528 {
 529     ACPI_STATUS             Status;
 530     ACPI_THREAD_STATE       *Thread;
 531     ACPI_THREAD_STATE       *PrevWalkList = AcpiGbl_CurrentWalkList;
 532     ACPI_WALK_STATE         *PreviousWalkState;
 533
 534
 535     ACPI_FUNCTION_TRACE (PsParseAml);
 536
 537     ACPI_DEBUG_PRINT ((ACPI_DB_PARSE,
 538         "Entered with WalkState=%p Aml=%p size=%X\n",
 539         WalkState, WalkState->ParserState.Aml,
 540         WalkState->ParserState.AmlSize));
 541
 542     if (!WalkState->ParserState.Aml)
 543     {
 544         return_ACPI_STATUS (AE_NULL_OBJECT);
 545     }
 546
 547     /* Create and initialize a new thread state */
 548
 549     Thread = AcpiUtCreateThreadState ();
 550     if (!Thread)
 551     {
 552         if (WalkState->MethodDesc)
 553         {
 554             /* Executing a control method - additional cleanup */
 555
 556             AcpiDsTerminateControlMethod (WalkState->MethodDesc, WalkState);
 557         }
 558
 559         AcpiDsDeleteWalkState (WalkState);
 560         return_ACPI_STATUS (AE_NO_MEMORY);
 561     }
 562
 563     WalkState->Thread = Thread;
 564
 565     /*
 566      * If executing a method, the starting SyncLevel is this method's
 567      * SyncLevel
 568      */
 569     if (WalkState->MethodDesc)
 570     {
 571         WalkState->Thread->CurrentSyncLevel = WalkState->MethodDesc->Method.SyncLevel;
 572     }
 573
 574     AcpiDsPushWalkState (WalkState, Thread);
 575
 576     /*
 577      * This global allows the AML debugger to get a handle to the currently
 578      * executing control method.
 579      */
 580     AcpiGbl_CurrentWalkList = Thread;
 581
 582     /*
 583      * Execute the walk loop as long as there is a valid Walk State.  This
 584      * handles nested control method invocations without recursion.
 585      */
 586     ACPI_DEBUG_PRINT ((ACPI_DB_PARSE, "State=%p\n", WalkState));
 587
 588     Status = AE_OK;
 589     while (WalkState)
 590     {
 591         if (ACPI_SUCCESS (Status))
 592         {
 593             /*
 594              * The ParseLoop executes AML until the method terminates
 595              * or calls another method.
 596              */
 597             Status = AcpiPsParseLoop (WalkState);
 598         }
 599
 600         ACPI_DEBUG_PRINT ((ACPI_DB_PARSE,
 601             "Completed one call to walk loop, %s State=%p\n",
 602             AcpiFormatException (Status), WalkState));
 603
 604         if (Status == AE_CTRL_TRANSFER)
 605         {
 606             /*
 607              * A method call was detected.
 608              * Transfer control to the called control method
 609              */
 610             Status = AcpiDsCallControlMethod (Thread, WalkState, NULL);
 611             if (ACPI_FAILURE (Status))
 612             {
 613                 Status = AcpiDsMethodError (Status, WalkState);
 614             }
 615
 616             /*
 617              * If the transfer to the new method method call worked, a new walk
 618              * state was created -- get it
 619              */
 620             WalkState = AcpiDsGetCurrentWalkState (Thread);
 621             continue;
 622         }
 623         else if (Status == AE_CTRL_TERMINATE)
 624         {
 625             Status = AE_OK;
 626         }
 627         else if ((Status != AE_OK) && (WalkState->MethodDesc))
 628         {
 629             /* Either the method parse or actual execution failed */
 630
 631             ACPI_ERROR_METHOD ("Method parse/execution failed",
 632                 WalkState->MethodNode, NULL, Status);
 633
 634             /* Check for possible multi-thread reentrancy problem */
 635
 636             if ((Status == AE_ALREADY_EXISTS) &&
 637                 (!(WalkState->MethodDesc->Method.InfoFlags & ACPI_METHOD_SERIALIZED)))
 638             {
 639                 /*
 640                  * Method is not serialized and tried to create an object
 641                  * twice. The probable cause is that the method cannot
 642                  * handle reentrancy. Mark as "pending serialized" now, and
 643                  * then mark "serialized" when the last thread exits.
 644                  */
 645                 WalkState->MethodDesc->Method.InfoFlags |=
 646                     ACPI_METHOD_SERIALIZED_PENDING;
 647             }
 648         }
 649
 650         /* We are done with this walk, move on to the parent if any */
 651
 652         WalkState = AcpiDsPopWalkState (Thread);
 653
 654         /* Reset the current scope to the beginning of scope stack */
 655
 656         AcpiDsScopeStackClear (WalkState);
 657
 658         /*
 659          * If we just returned from the execution of a control method or if we
 660          * encountered an error during the method parse phase, there's lots of
 661          * cleanup to do
 662          */
 663         if (((WalkState->ParseFlags & ACPI_PARSE_MODE_MASK) == ACPI_PARSE_EXECUTE) ||
 664             (ACPI_FAILURE (Status)))
 665         {
 666             AcpiDsTerminateControlMethod (WalkState->MethodDesc, WalkState);
 667         }
 668
 669         /* Delete this walk state and all linked control states */
 670
 671         AcpiPsCleanupScope (&WalkState->ParserState);
 672         PreviousWalkState = WalkState;
 673
 674         ACPI_DEBUG_PRINT ((ACPI_DB_PARSE,
 675             "ReturnValue=%p, ImplicitValue=%p State=%p\n",
 676             WalkState->ReturnDesc, WalkState->ImplicitReturnObj, WalkState));
 677
 678         /* Check if we have restarted a preempted walk */
 679
 680         WalkState = AcpiDsGetCurrentWalkState (Thread);
 681         if (WalkState)
 682         {
 683             if (ACPI_SUCCESS (Status))
 684             {
 685                 /*
 686                  * There is another walk state, restart it.
 687                  * If the method return value is not used by the parent,
 688                  * The object is deleted
 689                  */
 690                 if (!PreviousWalkState->ReturnDesc)
 691                 {
 692                     /*
 693                      * In slack mode execution, if there is no return value
 694                      * we should implicitly return zero (0) as a default value.
 695                      */
 696                     if (AcpiGbl_EnableInterpreterSlack &&
 697                         !PreviousWalkState->ImplicitReturnObj)
 698                     {
 699                         PreviousWalkState->ImplicitReturnObj =
 700                             AcpiUtCreateIntegerObject ((UINT64) 0);
 701                         if (!PreviousWalkState->ImplicitReturnObj)
 702                         {
 703                             return_ACPI_STATUS (AE_NO_MEMORY);
 704                         }
 705                     }
 706
 707                     /* Restart the calling control method */
 708
 709                     Status = AcpiDsRestartControlMethod (WalkState,
 710                                 PreviousWalkState->ImplicitReturnObj);
 711                 }
 712                 else
 713                 {
 714                     /*
 715                      * We have a valid return value, delete any implicit
 716                      * return value.
 717                      */
 718                     AcpiDsClearImplicitReturn (PreviousWalkState);
 719
 720                     Status = AcpiDsRestartControlMethod (WalkState,
 721                                 PreviousWalkState->ReturnDesc);
 722                 }
 723                 if (ACPI_SUCCESS (Status))
 724                 {
 725                     WalkState->WalkType |= ACPI_WALK_METHOD_RESTART;
 726                 }
 727             }
 728             else
 729             {
 730                 /* On error, delete any return object or implicit return */
 731
 732                 AcpiUtRemoveReference (PreviousWalkState->ReturnDesc);
 733                 AcpiDsClearImplicitReturn (PreviousWalkState);
 734             }
 735         }
 736
 737         /*
 738          * Just completed a 1st-level method, save the final internal return
 739          * value (if any)
 740          */
 741         else if (PreviousWalkState->CallerReturnDesc)
 742         {
 743             if (PreviousWalkState->ImplicitReturnObj)
 744             {
 745                 *(PreviousWalkState->CallerReturnDesc) =
 746                     PreviousWalkState->ImplicitReturnObj;
 747             }
 748             else
 749             {
 750                  /* NULL if no return value */
 751
 752                 *(PreviousWalkState->CallerReturnDesc) =
 753                     PreviousWalkState->ReturnDesc;
 754             }
 755         }
 756         else
 757         {
 758             if (PreviousWalkState->ReturnDesc)
 759             {
 760                 /* Caller doesn't want it, must delete it */
 761
 762                 AcpiUtRemoveReference (PreviousWalkState->ReturnDesc);
 763             }
 764             if (PreviousWalkState->ImplicitReturnObj)
 765             {
 766                 /* Caller doesn't want it, must delete it */
 767
 768                 AcpiUtRemoveReference (PreviousWalkState->ImplicitReturnObj);
 769             }
 770         }
 771
 772         AcpiDsDeleteWalkState (PreviousWalkState);
 773     }
 774
 775     /* Normal exit */
 776
 777     AcpiExReleaseAllMutexes (Thread);
 778     AcpiUtDeleteGenericState (ACPI_CAST_PTR (ACPI_GENERIC_STATE, Thread));
 779     AcpiGbl_CurrentWalkList = PrevWalkList;
 780     return_ACPI_STATUS (Status);
 781 }
 782
 783