FreeBSD/Linux Kernel Cross Reference
sys/contrib/dev/acpica/components/executer/exconfig.c

     /******************************************************************************
      *
      * Module Name: exconfig - Namespace reconfiguration (Load/Unload opcodes)
      *
      *****************************************************************************/
     
     /******************************************************************************
      *
      * 1. Copyright Notice
     *
     * Some or all of this work - Copyright (c) 1999 - 2022, Intel Corp.
     * All rights reserved.
     *
     * 2. License
     *
     * 2.1. This is your license from Intel Corp. under its intellectual property
     * rights. You may have additional license terms from the party that provided
     * you this software, covering your right to use that party's intellectual
     * property rights.
     *
     * 2.2. Intel grants, free of charge, to any person ("Licensee") obtaining a
     * copy of the source code appearing in this file ("Covered Code") an
     * irrevocable, perpetual, worldwide license under Intel's copyrights in the
     * base code distributed originally by Intel ("Original Intel Code") to copy,
     * make derivatives, distribute, use and display any portion of the Covered
     * Code in any form, with the right to sublicense such rights; and
     *
     * 2.3. Intel grants Licensee a non-exclusive and non-transferable patent
     * license (with the right to sublicense), under only those claims of Intel
     * patents that are infringed by the Original Intel Code, to make, use, sell,
     * offer to sell, and import the Covered Code and derivative works thereof
     * solely to the minimum extent necessary to exercise the above copyright
     * license, and in no event shall the patent license extend to any additions
     * to or modifications of the Original Intel Code. No other license or right
     * is granted directly or by implication, estoppel or otherwise;
     *
     * The above copyright and patent license is granted only if the following
     * conditions are met:
     *
     * 3. Conditions
     *
     * 3.1. Redistribution of Source with Rights to Further Distribute Source.
     * Redistribution of source code of any substantial portion of the Covered
     * Code or modification with rights to further distribute source must include
     * the above Copyright Notice, the above License, this list of Conditions,
     * and the following Disclaimer and Export Compliance provision. In addition,
     * Licensee must cause all Covered Code to which Licensee contributes to
     * contain a file documenting the changes Licensee made to create that Covered
     * Code and the date of any change. Licensee must include in that file the
     * documentation of any changes made by any predecessor Licensee. Licensee
     * must include a prominent statement that the modification is derived,
     * directly or indirectly, from Original Intel Code.
     *
     * 3.2. Redistribution of Source with no Rights to Further Distribute Source.
     * Redistribution of source code of any substantial portion of the Covered
     * Code or modification without rights to further distribute source must
     * include the following Disclaimer and Export Compliance provision in the
     * documentation and/or other materials provided with distribution. In
     * addition, Licensee may not authorize further sublicense of source of any
     * portion of the Covered Code, and must include terms to the effect that the
     * license from Licensee to its licensee is limited to the intellectual
     * property embodied in the software Licensee provides to its licensee, and
     * not to intellectual property embodied in modifications its licensee may
     * make.
     *
     * 3.3. Redistribution of Executable. Redistribution in executable form of any
     * substantial portion of the Covered Code or modification must reproduce the
     * above Copyright Notice, and the following Disclaimer and Export Compliance
     * provision in the documentation and/or other materials provided with the
     * distribution.
     *
     * 3.4. Intel retains all right, title, and interest in and to the Original
     * Intel Code.
     *
     * 3.5. Neither the name Intel nor any other trademark owned or controlled by
     * Intel shall be used in advertising or otherwise to promote the sale, use or
     * other dealings in products derived from or relating to the Covered Code
     * without prior written authorization from Intel.
     *
     * 4. Disclaimer and Export Compliance
     *
     * 4.1. INTEL MAKES NO WARRANTY OF ANY KIND REGARDING ANY SOFTWARE PROVIDED
     * HERE. ANY SOFTWARE ORIGINATING FROM INTEL OR DERIVED FROM INTEL SOFTWARE
     * IS PROVIDED "AS IS," AND INTEL WILL NOT PROVIDE ANY SUPPORT, ASSISTANCE,
     * INSTALLATION, TRAINING OR OTHER SERVICES. INTEL WILL NOT PROVIDE ANY
    
     * UPDATES, ENHANCEMENTS OR EXTENSIONS. INTEL SPECIFICALLY DISCLAIMS ANY
     * IMPLIED WARRANTIES OF MERCHANTABILITY, NONINFRINGEMENT AND FITNESS FOR A
     * PARTICULAR PURPOSE.
     *
     * 4.2. IN NO EVENT SHALL INTEL HAVE ANY LIABILITY TO LICENSEE, ITS LICENSEES
     * OR ANY OTHER THIRD PARTY, FOR ANY LOST PROFITS, LOST DATA, LOSS OF USE OR
     * COSTS OF PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, OR FOR ANY INDIRECT,
     * SPECIAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS AGREEMENT, UNDER ANY
     * CAUSE OF ACTION OR THEORY OF LIABILITY, AND IRRESPECTIVE OF WHETHER INTEL
     * HAS ADVANCE NOTICE OF THE POSSIBILITY OF SUCH DAMAGES. THESE LIMITATIONS
     * SHALL APPLY NOTWITHSTANDING THE FAILURE OF THE ESSENTIAL PURPOSE OF ANY
     * LIMITED REMEDY.
     *
    * 4.3. Licensee shall not export, either directly or indirectly, any of this
    * software or system incorporating such software without first obtaining any
    * required license or other approval from the U. S. Department of Commerce or
    * any other agency or department of the United States Government. In the
    * event Licensee exports any such software from the United States or
    * re-exports any such software from a foreign destination, Licensee shall
    * ensure that the distribution and export/re-export of the software is in
    * compliance with all laws, regulations, orders, or other restrictions of the
    * U.S. Export Administration Regulations. Licensee agrees that neither it nor
    * any of its subsidiaries will export/re-export any technical data, process,
    * software, or service, directly or indirectly, to any country for which the
    * United States government or any agency thereof requires an export license,
    * other governmental approval, or letter of assurance, without first obtaining
    * such license, approval or letter.
    *
    *****************************************************************************
    *
    * Alternatively, you may choose to be licensed under the terms of the
    * following license:
    *
    * Redistribution and use in source and binary forms, with or without
    * modification, are permitted provided that the following conditions
    * are met:
    * 1. Redistributions of source code must retain the above copyright
    *    notice, this list of conditions, and the following disclaimer,
    *    without modification.
    * 2. Redistributions in binary form must reproduce at minimum a disclaimer
    *    substantially similar to the "NO WARRANTY" disclaimer below
    *    ("Disclaimer") and any redistribution must be conditioned upon
    *    including a substantially similar Disclaimer requirement for further
    *    binary redistribution.
    * 3. Neither the names of the above-listed copyright holders nor the names
    *    of any contributors may be used to endorse or promote products derived
    *    from this software without specific prior written permission.
    *
    * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
    * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
    * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
    * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
    * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
    * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    *
    * Alternatively, you may choose to be licensed under the terms of the
    * GNU General Public License ("GPL") version 2 as published by the Free
    * Software Foundation.
    *
    *****************************************************************************/
   
   #include <contrib/dev/acpica/include/acpi.h>
   #include <contrib/dev/acpica/include/accommon.h>
   #include <contrib/dev/acpica/include/acinterp.h>
   #include <contrib/dev/acpica/include/acnamesp.h>
   #include <contrib/dev/acpica/include/actables.h>
   #include <contrib/dev/acpica/include/acdispat.h>
   #include <contrib/dev/acpica/include/acevents.h>
   #include <contrib/dev/acpica/include/amlcode.h>
   
   
   #define _COMPONENT          ACPI_EXECUTER
           ACPI_MODULE_NAME    ("exconfig")
   
   /* Local prototypes */
   
   static ACPI_STATUS
   AcpiExAddTable (
       UINT32                  TableIndex,
       ACPI_OPERAND_OBJECT     **DdbHandle);
   
   static ACPI_STATUS
   AcpiExRegionRead (
       ACPI_OPERAND_OBJECT     *ObjDesc,
       UINT32                  Length,
       UINT8                   *Buffer);
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExAddTable
    *
    * PARAMETERS:  Table               - Pointer to raw table
    *              ParentNode          - Where to load the table (scope)
    *              DdbHandle           - Where to return the table handle.
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Common function to Install and Load an ACPI table with a
    *              returned table handle.
    *
    ******************************************************************************/
   
   static ACPI_STATUS
   AcpiExAddTable (
       UINT32                  TableIndex,
       ACPI_OPERAND_OBJECT     **DdbHandle)
   {
       ACPI_OPERAND_OBJECT     *ObjDesc;
   
   
       ACPI_FUNCTION_TRACE (ExAddTable);
   
   
       /* Create an object to be the table handle */
   
       ObjDesc = AcpiUtCreateInternalObject (ACPI_TYPE_LOCAL_REFERENCE);
       if (!ObjDesc)
       {
           return_ACPI_STATUS (AE_NO_MEMORY);
       }
   
       /* Init the table handle */
   
       ObjDesc->Common.Flags |= AOPOBJ_DATA_VALID;
       ObjDesc->Reference.Class = ACPI_REFCLASS_TABLE;
       ObjDesc->Reference.Value = TableIndex;
       *DdbHandle = ObjDesc;
       return_ACPI_STATUS (AE_OK);
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExLoadTableOp
    *
    * PARAMETERS:  WalkState           - Current state with operands
    *              ReturnDesc          - Where to store the return object
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Load an ACPI table from the RSDT/XSDT
    *
    ******************************************************************************/
   
   ACPI_STATUS
   AcpiExLoadTableOp (
       ACPI_WALK_STATE         *WalkState,
       ACPI_OPERAND_OBJECT     **ReturnDesc)
   {
       ACPI_STATUS             Status;
       ACPI_OPERAND_OBJECT     **Operand = &WalkState->Operands[0];
       ACPI_NAMESPACE_NODE     *ParentNode;
       ACPI_NAMESPACE_NODE     *StartNode;
       ACPI_NAMESPACE_NODE     *ParameterNode = NULL;
       ACPI_OPERAND_OBJECT     *ReturnObj;
       ACPI_OPERAND_OBJECT     *DdbHandle;
       UINT32                  TableIndex;
   
   
       ACPI_FUNCTION_TRACE (ExLoadTableOp);
   
   
       /* Create the return object */
   
       ReturnObj = AcpiUtCreateIntegerObject ((UINT64) 0);
       if (!ReturnObj)
       {
           return_ACPI_STATUS (AE_NO_MEMORY);
       }
   
       *ReturnDesc = ReturnObj;
   
       /* Find the ACPI table in the RSDT/XSDT */
   
       AcpiExExitInterpreter ();
       Status = AcpiTbFindTable (
           Operand[0]->String.Pointer,
           Operand[1]->String.Pointer,
           Operand[2]->String.Pointer, &TableIndex);
       AcpiExEnterInterpreter ();
       if (ACPI_FAILURE (Status))
       {
           if (Status != AE_NOT_FOUND)
           {
               return_ACPI_STATUS (Status);
           }
   
           /* Table not found, return an Integer=0 and AE_OK */
   
           return_ACPI_STATUS (AE_OK);
       }
   
       /* Default nodes */
   
       StartNode = WalkState->ScopeInfo->Scope.Node;
       ParentNode = AcpiGbl_RootNode;
   
       /* RootPath (optional parameter) */
   
       if (Operand[3]->String.Length > 0)
       {
           /*
            * Find the node referenced by the RootPathString. This is the
            * location within the namespace where the table will be loaded.
            */
           Status = AcpiNsGetNodeUnlocked (StartNode,
               Operand[3]->String.Pointer, ACPI_NS_SEARCH_PARENT,
               &ParentNode);
           if (ACPI_FAILURE (Status))
           {
               return_ACPI_STATUS (Status);
           }
       }
   
       /* ParameterPath (optional parameter) */
   
       if (Operand[4]->String.Length > 0)
       {
           if ((Operand[4]->String.Pointer[0] != AML_ROOT_PREFIX) &&
               (Operand[4]->String.Pointer[0] != AML_PARENT_PREFIX))
           {
               /*
                * Path is not absolute, so it will be relative to the node
                * referenced by the RootPathString (or the NS root if omitted)
                */
               StartNode = ParentNode;
           }
   
           /* Find the node referenced by the ParameterPathString */
   
           Status = AcpiNsGetNodeUnlocked (StartNode,
               Operand[4]->String.Pointer, ACPI_NS_SEARCH_PARENT,
               &ParameterNode);
           if (ACPI_FAILURE (Status))
           {
               return_ACPI_STATUS (Status);
           }
       }
   
       /* Load the table into the namespace */
   
       ACPI_INFO (("Dynamic OEM Table Load:"));
       AcpiExExitInterpreter ();
       Status = AcpiTbLoadTable (TableIndex, ParentNode);
       AcpiExEnterInterpreter ();
       if (ACPI_FAILURE (Status))
       {
           return_ACPI_STATUS (Status);
       }
   
       Status = AcpiExAddTable (TableIndex, &DdbHandle);
       if (ACPI_FAILURE (Status))
       {
           return_ACPI_STATUS (Status);
       }
   
       /* Complete the initialization/resolution of new objects */
   
       AcpiExExitInterpreter();
       AcpiNsInitializeObjects();
       AcpiExEnterInterpreter();
   
       /* Parameter Data (optional) */
   
       if (ParameterNode)
       {
           /* Store the parameter data into the optional parameter object */
   
           Status = AcpiExStore (Operand[5],
               ACPI_CAST_PTR (ACPI_OPERAND_OBJECT, ParameterNode), WalkState);
           if (ACPI_FAILURE (Status))
           {
               (void) AcpiExUnloadTable (DdbHandle);
   
               AcpiUtRemoveReference (DdbHandle);
               return_ACPI_STATUS (Status);
           }
       }
   
       /* Remove the reference to DdbHandle created by AcpiExAddTable above */
   
       AcpiUtRemoveReference (DdbHandle);
   
       /* Return -1 (non-zero) indicates success */
   
       ReturnObj->Integer.Value = 0xFFFFFFFFFFFFFFFF;
       return_ACPI_STATUS (Status);
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExRegionRead
    *
    * PARAMETERS:  ObjDesc         - Region descriptor
    *              Length          - Number of bytes to read
    *              Buffer          - Pointer to where to put the data
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Read data from an operation region. The read starts from the
    *              beginning of the region.
    *
    ******************************************************************************/
   
   static ACPI_STATUS
   AcpiExRegionRead (
       ACPI_OPERAND_OBJECT     *ObjDesc,
       UINT32                  Length,
       UINT8                   *Buffer)
   {
       ACPI_STATUS             Status;
       UINT64                  Value;
       UINT32                  RegionOffset = 0;
       UINT32                  i;
   
   
       /* Bytewise reads */
   
       for (i = 0; i < Length; i++)
       {
           Status = AcpiEvAddressSpaceDispatch (ObjDesc, NULL, ACPI_READ,
               RegionOffset, 8, &Value);
           if (ACPI_FAILURE (Status))
           {
               return (Status);
           }
   
           *Buffer = (UINT8) Value;
           Buffer++;
           RegionOffset++;
       }
   
       return (AE_OK);
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExLoadOp
    *
    * PARAMETERS:  ObjDesc         - Region or Buffer/Field where the table will be
    *                                obtained
    *              Target          - Where the status of the load will be stored
    *              WalkState       - Current state
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Load an ACPI table from a field or operation region
    *
    * NOTE: Region Fields (Field, BankField, IndexFields) are resolved to buffer
    *       objects before this code is reached.
    *
    *       If source is an operation region, it must refer to SystemMemory, as
    *       per the ACPI specification.
    *
    ******************************************************************************/
   
   ACPI_STATUS
   AcpiExLoadOp (
       ACPI_OPERAND_OBJECT     *ObjDesc,
       ACPI_OPERAND_OBJECT     *Target,
       ACPI_WALK_STATE         *WalkState)
   {
       ACPI_OPERAND_OBJECT     *DdbHandle;
       ACPI_TABLE_HEADER       *TableHeader;
       ACPI_TABLE_HEADER       *Table;
       UINT32                  TableIndex;
       ACPI_STATUS             Status;
       UINT32                  Length;
   
   
       ACPI_FUNCTION_TRACE (ExLoadOp);
   
   
       if (Target->Common.DescriptorType == ACPI_DESC_TYPE_NAMED)
       {
           Target = AcpiNsGetAttachedObject (ACPI_CAST_PTR (ACPI_NAMESPACE_NODE, Target));
       }
       if (Target->Common.Type != ACPI_TYPE_INTEGER)
       {
           ACPI_ERROR ((AE_INFO, "Type not integer: %X", Target->Common.Type));
           return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
       }
   
       Target->Integer.Value = 0;
   
       /* Source Object can be either an OpRegion or a Buffer/Field */
   
       switch (ObjDesc->Common.Type)
       {
       case ACPI_TYPE_REGION:
   
           ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
               "Load table from Region %p\n", ObjDesc));
   
           /* Region must be SystemMemory (from ACPI spec) */
   
           if (ObjDesc->Region.SpaceId != ACPI_ADR_SPACE_SYSTEM_MEMORY)
           {
               return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
           }
   
           /*
            * If the Region Address and Length have not been previously
            * evaluated, evaluate them now and save the results.
            */
           if (!(ObjDesc->Common.Flags & AOPOBJ_DATA_VALID))
           {
               Status = AcpiDsGetRegionArguments (ObjDesc);
               if (ACPI_FAILURE (Status))
               {
                   return_ACPI_STATUS (Status);
               }
           }
   
           /* Get the table header first so we can get the table length */
   
           TableHeader = ACPI_ALLOCATE (sizeof (ACPI_TABLE_HEADER));
           if (!TableHeader)
           {
               return_ACPI_STATUS (AE_NO_MEMORY);
           }
   
           Status = AcpiExRegionRead (ObjDesc, sizeof (ACPI_TABLE_HEADER),
               ACPI_CAST_PTR (UINT8, TableHeader));
           Length = TableHeader->Length;
           ACPI_FREE (TableHeader);
   
           if (ACPI_FAILURE (Status))
           {
               return_ACPI_STATUS (Status);
           }
   
           /* Must have at least an ACPI table header */
   
           if (Length < sizeof (ACPI_TABLE_HEADER))
           {
               return_ACPI_STATUS (AE_INVALID_TABLE_LENGTH);
           }
   
           /*
            * The original implementation simply mapped the table, with no copy.
            * However, the memory region is not guaranteed to remain stable and
            * we must copy the table to a local buffer. For example, the memory
            * region is corrupted after suspend on some machines. Dynamically
            * loaded tables are usually small, so this overhead is minimal.
            *
            * The latest implementation (5/2009) does not use a mapping at all.
            * We use the low-level operation region interface to read the table
            * instead of the obvious optimization of using a direct mapping.
            * This maintains a consistent use of operation regions across the
            * entire subsystem. This is important if additional processing must
            * be performed in the (possibly user-installed) operation region
            * handler. For example, AcpiExec and ASLTS depend on this.
            */
   
           /* Allocate a buffer for the table */
   
           Table = ACPI_ALLOCATE (Length);
           if (!Table)
           {
               return_ACPI_STATUS (AE_NO_MEMORY);
           }
   
           /* Read the entire table */
   
           Status = AcpiExRegionRead (ObjDesc, Length,
               ACPI_CAST_PTR (UINT8, Table));
           if (ACPI_FAILURE (Status))
           {
               ACPI_FREE (Table);
               return_ACPI_STATUS (Status);
           }
           break;
   
       case ACPI_TYPE_BUFFER: /* Buffer or resolved RegionField */
   
           ACPI_DEBUG_PRINT ((ACPI_DB_EXEC,
               "Load table from Buffer or Field %p\n", ObjDesc));
   
           /* Must have at least an ACPI table header */
   
           if (ObjDesc->Buffer.Length < sizeof (ACPI_TABLE_HEADER))
           {
               return_ACPI_STATUS (AE_INVALID_TABLE_LENGTH);
           }
   
           /* Get the actual table length from the table header */
   
           TableHeader = ACPI_CAST_PTR (
               ACPI_TABLE_HEADER, ObjDesc->Buffer.Pointer);
           Length = TableHeader->Length;
   
           /* Table cannot extend beyond the buffer */
   
           if (Length > ObjDesc->Buffer.Length)
           {
               return_ACPI_STATUS (AE_AML_BUFFER_LIMIT);
           }
           if (Length < sizeof (ACPI_TABLE_HEADER))
           {
               return_ACPI_STATUS (AE_INVALID_TABLE_LENGTH);
           }
   
           /*
            * Copy the table from the buffer because the buffer could be
            * modified or even deleted in the future
            */
           Table = ACPI_ALLOCATE (Length);
           if (!Table)
           {
               return_ACPI_STATUS (AE_NO_MEMORY);
           }
   
           memcpy (Table, TableHeader, Length);
           break;
   
       default:
   
           return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
       }
   
       /* Install the new table into the local data structures */
   
       ACPI_INFO (("Dynamic OEM Table Load:"));
       AcpiExExitInterpreter ();
       Status = AcpiTbInstallAndLoadTable (ACPI_PTR_TO_PHYSADDR (Table),
           ACPI_TABLE_ORIGIN_INTERNAL_VIRTUAL, Table, TRUE, &TableIndex);
       AcpiExEnterInterpreter ();
       if (ACPI_FAILURE (Status))
       {
           /* Delete allocated table buffer */
   
           ACPI_FREE (Table);
           return_ACPI_STATUS (Status);
       }
   
       /*
        * Add the table to the namespace.
        *
        * Note: Load the table objects relative to the root of the namespace.
        * This appears to go against the ACPI specification, but we do it for
        * compatibility with other ACPI implementations.
        */
       Status = AcpiExAddTable (TableIndex, &DdbHandle);
       if (ACPI_FAILURE (Status))
       {
           return_ACPI_STATUS (Status);
       }
   
       /* Complete the initialization/resolution of new objects */
   
       AcpiExExitInterpreter ();
       AcpiNsInitializeObjects ();
       AcpiExEnterInterpreter ();
   
       /* Remove the reference to DdbHandle created by AcpiExAddTable above */
   
       AcpiUtRemoveReference (DdbHandle);
   
       /* Return -1 (non-zero) indicates success */
   
       Target->Integer.Value = 0xFFFFFFFFFFFFFFFF;
       return_ACPI_STATUS (Status);
   }
   
   
   /*******************************************************************************
    *
    * FUNCTION:    AcpiExUnloadTable
    *
    * PARAMETERS:  DdbHandle           - Handle to a previously loaded table
    *
    * RETURN:      Status
    *
    * DESCRIPTION: Unload an ACPI table
    *
    ******************************************************************************/
   
   ACPI_STATUS
   AcpiExUnloadTable (
       ACPI_OPERAND_OBJECT     *DdbHandle)
   {
       ACPI_STATUS             Status = AE_OK;
       ACPI_OPERAND_OBJECT     *TableDesc = DdbHandle;
       UINT32                  TableIndex;
   
   
       ACPI_FUNCTION_TRACE (ExUnloadTable);
   
   
       /*
        * Temporarily emit a warning so that the ASL for the machine can be
        * hopefully obtained. This is to say that the Unload() operator is
        * extremely rare if not completely unused.
        */
       ACPI_WARNING ((AE_INFO,
           "Received request to unload an ACPI table"));
   
       /*
        * May 2018: Unload is no longer supported for the following reasons:
        * 1) A correct implementation on some hosts may not be possible.
        * 2) Other ACPI implementations do not correctly/fully support it.
        * 3) It requires host device driver support which does not exist.
        *    (To properly support namespace unload out from underneath.)
        * 4) This AML operator has never been seen in the field.
        */
       ACPI_EXCEPTION ((AE_INFO, AE_NOT_IMPLEMENTED,
           "AML Unload operator is not supported"));
   
       /*
        * Validate the handle
        * Although the handle is partially validated in AcpiExReconfiguration()
        * when it calls AcpiExResolveOperands(), the handle is more completely
        * validated here.
        *
        * Handle must be a valid operand object of type reference. Also, the
        * DdbHandle must still be marked valid (table has not been previously
        * unloaded)
        */
       if ((!DdbHandle) ||
           (ACPI_GET_DESCRIPTOR_TYPE (DdbHandle) != ACPI_DESC_TYPE_OPERAND) ||
           (DdbHandle->Common.Type != ACPI_TYPE_LOCAL_REFERENCE) ||
           (!(DdbHandle->Common.Flags & AOPOBJ_DATA_VALID)))
       {
           return_ACPI_STATUS (AE_AML_OPERAND_TYPE);
       }
   
       /* Get the table index from the DdbHandle */
   
       TableIndex = TableDesc->Reference.Value;
   
       /*
        * Release the interpreter lock so that the table lock won't have
        * strict order requirement against it.
        */
       AcpiExExitInterpreter ();
       Status = AcpiTbUnloadTable (TableIndex);
       AcpiExEnterInterpreter ();
   
       /*
        * Invalidate the handle. We do this because the handle may be stored
        * in a named object and may not be actually deleted until much later.
        */
       if (ACPI_SUCCESS (Status))
       {
           DdbHandle->Common.Flags &= ~AOPOBJ_DATA_VALID;
       }
       return_ACPI_STATUS (Status);
   }

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