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      1 /*******************************************************************************
      2  *
      3  * Module Name: utresrc - Resource management utilities
      4  *
      5  ******************************************************************************/
      6 
      7 /*
      8  * Copyright (C) 2000 - 2025, Intel Corp.
      9  * All rights reserved.
     10  *
     11  * Redistribution and use in source and binary forms, with or without
     12  * modification, are permitted provided that the following conditions
     13  * are met:
     14  * 1. Redistributions of source code must retain the above copyright
     15  *    notice, this list of conditions, and the following disclaimer,
     16  *    without modification.
     17  * 2. Redistributions in binary form must reproduce at minimum a disclaimer
     18  *    substantially similar to the "NO WARRANTY" disclaimer below
     19  *    ("Disclaimer") and any redistribution must be conditioned upon
     20  *    including a substantially similar Disclaimer requirement for further
     21  *    binary redistribution.
     22  * 3. Neither the names of the above-listed copyright holders nor the names
     23  *    of any contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * Alternatively, this software may be distributed under the terms of the
     27  * GNU General Public License ("GPL") version 2 as published by the Free
     28  * Software Foundation.
     29  *
     30  * NO WARRANTY
     31  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     32  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     33  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     34  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     35  * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     36  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     37  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     38  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
     39  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
     40  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     41  * POSSIBILITY OF SUCH DAMAGES.
     42  */
     43 
     44 #include "acpi.h"
     45 #include "accommon.h"
     46 #include "acresrc.h"
     47 
     48 
     49 #define _COMPONENT          ACPI_UTILITIES
     50         ACPI_MODULE_NAME    ("utresrc")
     51 
     52 
     53 /*
     54  * Base sizes of the raw AML resource descriptors, indexed by resource type.
     55  * Zero indicates a reserved (and therefore invalid) resource type.
     56  */
     57 const UINT8                 AcpiGbl_ResourceAmlSizes[] =
     58 {
     59     /* Small descriptors */
     60 
     61     0,
     62     0,
     63     0,
     64     0,
     65     ACPI_AML_SIZE_SMALL (AML_RESOURCE_IRQ),
     66     ACPI_AML_SIZE_SMALL (AML_RESOURCE_DMA),
     67     ACPI_AML_SIZE_SMALL (AML_RESOURCE_START_DEPENDENT),
     68     ACPI_AML_SIZE_SMALL (AML_RESOURCE_END_DEPENDENT),
     69     ACPI_AML_SIZE_SMALL (AML_RESOURCE_IO),
     70     ACPI_AML_SIZE_SMALL (AML_RESOURCE_FIXED_IO),
     71     ACPI_AML_SIZE_SMALL (AML_RESOURCE_FIXED_DMA),
     72     0,
     73     0,
     74     0,
     75     ACPI_AML_SIZE_SMALL (AML_RESOURCE_VENDOR_SMALL),
     76     ACPI_AML_SIZE_SMALL (AML_RESOURCE_END_TAG),
     77 
     78     /* Large descriptors */
     79 
     80     0,
     81     ACPI_AML_SIZE_LARGE (AML_RESOURCE_MEMORY24),
     82     ACPI_AML_SIZE_LARGE (AML_RESOURCE_GENERIC_REGISTER),
     83     0,
     84     ACPI_AML_SIZE_LARGE (AML_RESOURCE_VENDOR_LARGE),
     85     ACPI_AML_SIZE_LARGE (AML_RESOURCE_MEMORY32),
     86     ACPI_AML_SIZE_LARGE (AML_RESOURCE_FIXED_MEMORY32),
     87     ACPI_AML_SIZE_LARGE (AML_RESOURCE_ADDRESS32),
     88     ACPI_AML_SIZE_LARGE (AML_RESOURCE_ADDRESS16),
     89     ACPI_AML_SIZE_LARGE (AML_RESOURCE_EXTENDED_IRQ),
     90     ACPI_AML_SIZE_LARGE (AML_RESOURCE_ADDRESS64),
     91     ACPI_AML_SIZE_LARGE (AML_RESOURCE_EXTENDED_ADDRESS64),
     92     ACPI_AML_SIZE_LARGE (AML_RESOURCE_GPIO),
     93     ACPI_AML_SIZE_LARGE (AML_RESOURCE_PIN_FUNCTION),
     94     ACPI_AML_SIZE_LARGE (AML_RESOURCE_COMMON_SERIALBUS),
     95     ACPI_AML_SIZE_LARGE (AML_RESOURCE_PIN_CONFIG),
     96     ACPI_AML_SIZE_LARGE (AML_RESOURCE_PIN_GROUP),
     97     ACPI_AML_SIZE_LARGE (AML_RESOURCE_PIN_GROUP_FUNCTION),
     98     ACPI_AML_SIZE_LARGE (AML_RESOURCE_PIN_GROUP_CONFIG),
     99     ACPI_AML_SIZE_LARGE (AML_RESOURCE_CLOCK_INPUT),
    100 
    101 };
    102 
    103 const UINT8                 AcpiGbl_ResourceAmlSerialBusSizes[] =
    104 {
    105     0,
    106     ACPI_AML_SIZE_LARGE (AML_RESOURCE_I2C_SERIALBUS),
    107     ACPI_AML_SIZE_LARGE (AML_RESOURCE_SPI_SERIALBUS),
    108     ACPI_AML_SIZE_LARGE (AML_RESOURCE_UART_SERIALBUS),
    109     ACPI_AML_SIZE_LARGE (AML_RESOURCE_CSI2_SERIALBUS),
    110 };
    111 
    112 
    113 /*
    114  * Resource types, used to validate the resource length field.
    115  * The length of fixed-length types must match exactly, variable
    116  * lengths must meet the minimum required length, etc.
    117  * Zero indicates a reserved (and therefore invalid) resource type.
    118  */
    119 static const UINT8          AcpiGbl_ResourceTypes[] =
    120 {
    121     /* Small descriptors */
    122 
    123     0,
    124     0,
    125     0,
    126     0,
    127     ACPI_SMALL_VARIABLE_LENGTH,     /* 04 IRQ */
    128     ACPI_FIXED_LENGTH,              /* 05 DMA */
    129     ACPI_SMALL_VARIABLE_LENGTH,     /* 06 StartDependentFunctions */
    130     ACPI_FIXED_LENGTH,              /* 07 EndDependentFunctions */
    131     ACPI_FIXED_LENGTH,              /* 08 IO */
    132     ACPI_FIXED_LENGTH,              /* 09 FixedIO */
    133     ACPI_FIXED_LENGTH,              /* 0A FixedDMA */
    134     0,
    135     0,
    136     0,
    137     ACPI_VARIABLE_LENGTH,           /* 0E VendorShort */
    138     ACPI_FIXED_LENGTH,              /* 0F EndTag */
    139 
    140     /* Large descriptors */
    141 
    142     0,
    143     ACPI_FIXED_LENGTH,              /* 01 Memory24 */
    144     ACPI_FIXED_LENGTH,              /* 02 GenericRegister */
    145     0,
    146     ACPI_VARIABLE_LENGTH,           /* 04 VendorLong */
    147     ACPI_FIXED_LENGTH,              /* 05 Memory32 */
    148     ACPI_FIXED_LENGTH,              /* 06 Memory32Fixed */
    149     ACPI_VARIABLE_LENGTH,           /* 07 Dword* address */
    150     ACPI_VARIABLE_LENGTH,           /* 08 Word* address */
    151     ACPI_VARIABLE_LENGTH,           /* 09 ExtendedIRQ */
    152     ACPI_VARIABLE_LENGTH,           /* 0A Qword* address */
    153     ACPI_FIXED_LENGTH,              /* 0B Extended* address */
    154     ACPI_VARIABLE_LENGTH,           /* 0C Gpio* */
    155     ACPI_VARIABLE_LENGTH,           /* 0D PinFunction */
    156     ACPI_VARIABLE_LENGTH,           /* 0E *SerialBus */
    157     ACPI_VARIABLE_LENGTH,           /* 0F PinConfig */
    158     ACPI_VARIABLE_LENGTH,           /* 10 PinGroup */
    159     ACPI_VARIABLE_LENGTH,           /* 11 PinGroupFunction */
    160     ACPI_VARIABLE_LENGTH,           /* 12 PinGroupConfig */
    161     ACPI_VARIABLE_LENGTH,           /* 13 ClockInput */
    162 };
    163 
    164 
    165 /*******************************************************************************
    166  *
    167  * FUNCTION:    AcpiUtWalkAmlResources
    168  *
    169  * PARAMETERS:  WalkState           - Current walk info
    170  * PARAMETERS:  Aml                 - Pointer to the raw AML resource template
    171  *              AmlLength           - Length of the entire template
    172  *              UserFunction        - Called once for each descriptor found. If
    173  *                                    NULL, a pointer to the EndTag is returned
    174  *              Context             - Passed to UserFunction
    175  *
    176  * RETURN:      Status
    177  *
    178  * DESCRIPTION: Walk a raw AML resource list(buffer). User function called
    179  *              once for each resource found.
    180  *
    181  ******************************************************************************/
    182 
    183 ACPI_STATUS
    184 AcpiUtWalkAmlResources (
    185     ACPI_WALK_STATE         *WalkState,
    186     UINT8                   *Aml,
    187     ACPI_SIZE               AmlLength,
    188     ACPI_WALK_AML_CALLBACK  UserFunction,
    189     void                    **Context)
    190 {
    191     ACPI_STATUS             Status;
    192     UINT8                   *EndAml;
    193     UINT8                   ResourceIndex;
    194     UINT32                  Length;
    195     UINT32                  Offset = 0;
    196     UINT8                   EndTag[2] = {0x79, 0x00};
    197 
    198 
    199     ACPI_FUNCTION_TRACE (UtWalkAmlResources);
    200 
    201 
    202     /* The absolute minimum resource template is one EndTag descriptor */
    203 
    204     if (AmlLength < sizeof (AML_RESOURCE_END_TAG))
    205     {
    206         return_ACPI_STATUS (AE_AML_NO_RESOURCE_END_TAG);
    207     }
    208 
    209     /* Point to the end of the resource template buffer */
    210 
    211     EndAml = Aml + AmlLength;
    212 
    213     /* Walk the byte list, abort on any invalid descriptor type or length */
    214 
    215     while (Aml < EndAml)
    216     {
    217         /* Validate the Resource Type and Resource Length */
    218 
    219         Status = AcpiUtValidateResource (WalkState, Aml, &ResourceIndex);
    220         if (ACPI_FAILURE (Status))
    221         {
    222             /*
    223              * Exit on failure. Cannot continue because the descriptor
    224              * length may be bogus also.
    225              */
    226             return_ACPI_STATUS (Status);
    227         }
    228 
    229         /* Get the length of this descriptor */
    230 
    231         Length = AcpiUtGetDescriptorLength (Aml);
    232 
    233         /* Invoke the user function */
    234 
    235         if (UserFunction)
    236         {
    237             Status = UserFunction (
    238                 Aml, Length, Offset, ResourceIndex, Context);
    239             if (ACPI_FAILURE (Status))
    240             {
    241                 return_ACPI_STATUS (Status);
    242             }
    243         }
    244 
    245         /* An EndTag descriptor terminates this resource template */
    246 
    247         if (AcpiUtGetResourceType (Aml) == ACPI_RESOURCE_NAME_END_TAG)
    248         {
    249             /*
    250              * There must be at least one more byte in the buffer for
    251              * the 2nd byte of the EndTag
    252              */
    253             if ((Aml + 1) >= EndAml)
    254             {
    255                 return_ACPI_STATUS (AE_AML_NO_RESOURCE_END_TAG);
    256             }
    257 
    258             /*
    259              * Don't attempt to perform any validation on the 2nd byte.
    260              * Although all known ASL compilers insert a zero for the 2nd
    261              * byte, it can also be a checksum (as per the ACPI spec),
    262              * and this is occasionally seen in the field. July 2017.
    263              */
    264 
    265             /* Return the pointer to the EndTag if requested */
    266 
    267             if (!UserFunction)
    268             {
    269                 *Context = Aml;
    270             }
    271 
    272             /* Normal exit */
    273 
    274             return_ACPI_STATUS (AE_OK);
    275         }
    276 
    277         Aml += Length;
    278         Offset += Length;
    279     }
    280 
    281     /* Did not find an EndTag descriptor */
    282 
    283     if (UserFunction)
    284     {
    285         /* Insert an EndTag anyway. AcpiRsGetListLength always leaves room */
    286 
    287         (void) AcpiUtValidateResource (WalkState, EndTag, &ResourceIndex);
    288         Status = UserFunction (EndTag, 2, Offset, ResourceIndex, Context);
    289         if (ACPI_FAILURE (Status))
    290         {
    291             return_ACPI_STATUS (Status);
    292         }
    293     }
    294 
    295     return_ACPI_STATUS (AE_AML_NO_RESOURCE_END_TAG);
    296 }
    297 
    298 
    299 /*******************************************************************************
    300  *
    301  * FUNCTION:    AcpiUtValidateResource
    302  *
    303  * PARAMETERS:  WalkState           - Current walk info
    304  *              Aml                 - Pointer to the raw AML resource descriptor
    305  *              ReturnIndex         - Where the resource index is returned. NULL
    306  *                                    if the index is not required.
    307  *
    308  * RETURN:      Status, and optionally the Index into the global resource tables
    309  *
    310  * DESCRIPTION: Validate an AML resource descriptor by checking the Resource
    311  *              Type and Resource Length. Returns an index into the global
    312  *              resource information/dispatch tables for later use.
    313  *
    314  ******************************************************************************/
    315 
    316 ACPI_STATUS
    317 AcpiUtValidateResource (
    318     ACPI_WALK_STATE         *WalkState,
    319     void                    *Aml,
    320     UINT8                   *ReturnIndex)
    321 {
    322     AML_RESOURCE            *AmlResource;
    323     UINT8                   ResourceType;
    324     UINT8                   ResourceIndex;
    325     ACPI_RS_LENGTH          ResourceLength;
    326     ACPI_RS_LENGTH          MinimumResourceLength;
    327 
    328 
    329     ACPI_FUNCTION_ENTRY ();
    330 
    331 
    332     /*
    333      * 1) Validate the ResourceType field (Byte 0)
    334      */
    335     ResourceType = ACPI_GET8 (Aml);
    336 
    337     /*
    338      * Byte 0 contains the descriptor name (Resource Type)
    339      * Examine the large/small bit in the resource header
    340      */
    341     if (ResourceType & ACPI_RESOURCE_NAME_LARGE)
    342     {
    343         /* Verify the large resource type (name) against the max */
    344 
    345         if (ResourceType > ACPI_RESOURCE_NAME_LARGE_MAX)
    346         {
    347             goto InvalidResource;
    348         }
    349 
    350         /*
    351          * Large Resource Type -- bits 6:0 contain the name
    352          * Translate range 0x80-0x8B to index range 0x10-0x1B
    353          */
    354         ResourceIndex = (UINT8) (ResourceType - 0x70);
    355     }
    356     else
    357     {
    358         /*
    359          * Small Resource Type -- bits 6:3 contain the name
    360          * Shift range to index range 0x00-0x0F
    361          */
    362         ResourceIndex = (UINT8)
    363             ((ResourceType & ACPI_RESOURCE_NAME_SMALL_MASK) >> 3);
    364     }
    365 
    366     /*
    367      * Check validity of the resource type, via AcpiGbl_ResourceTypes.
    368      * Zero indicates an invalid resource.
    369      */
    370     if (!AcpiGbl_ResourceTypes[ResourceIndex])
    371     {
    372         goto InvalidResource;
    373     }
    374 
    375     /*
    376      * Validate the ResourceLength field. This ensures that the length
    377      * is at least reasonable, and guarantees that it is non-zero.
    378      */
    379     ResourceLength = AcpiUtGetResourceLength (Aml);
    380     MinimumResourceLength = AcpiGbl_ResourceAmlSizes[ResourceIndex];
    381 
    382     /* Validate based upon the type of resource - fixed length or variable */
    383 
    384     switch (AcpiGbl_ResourceTypes[ResourceIndex])
    385     {
    386     case ACPI_FIXED_LENGTH:
    387 
    388         /* Fixed length resource, length must match exactly */
    389 
    390         if (ResourceLength != MinimumResourceLength)
    391         {
    392             goto BadResourceLength;
    393         }
    394         break;
    395 
    396     case ACPI_VARIABLE_LENGTH:
    397 
    398         /* Variable length resource, length must be at least the minimum */
    399 
    400         if (ResourceLength < MinimumResourceLength)
    401         {
    402             goto BadResourceLength;
    403         }
    404         break;
    405 
    406     case ACPI_SMALL_VARIABLE_LENGTH:
    407 
    408         /* Small variable length resource, length can be (Min) or (Min-1) */
    409 
    410         if ((ResourceLength > MinimumResourceLength) ||
    411             (ResourceLength < (MinimumResourceLength - 1)))
    412         {
    413             goto BadResourceLength;
    414         }
    415         break;
    416 
    417     default:
    418 
    419         /* Shouldn't happen (because of validation earlier), but be sure */
    420 
    421         goto InvalidResource;
    422     }
    423 
    424     AmlResource = ACPI_CAST_PTR (AML_RESOURCE, Aml);
    425     if (ResourceType == ACPI_RESOURCE_NAME_SERIAL_BUS)
    426     {
    427         /* Validate the BusType field */
    428 
    429         if ((AmlResource->CommonSerialBus.Type == 0) ||
    430             (AmlResource->CommonSerialBus.Type > AML_RESOURCE_MAX_SERIALBUSTYPE))
    431         {
    432             if (WalkState)
    433             {
    434                 ACPI_ERROR ((AE_INFO,
    435                     "Invalid/unsupported SerialBus resource descriptor: BusType 0x%2.2X",
    436                     AmlResource->CommonSerialBus.Type));
    437             }
    438             return (AE_AML_INVALID_RESOURCE_TYPE);
    439         }
    440     }
    441 
    442     /* Optionally return the resource table index */
    443 
    444     if (ReturnIndex)
    445     {
    446         *ReturnIndex = ResourceIndex;
    447     }
    448 
    449     return (AE_OK);
    450 
    451 
    452 InvalidResource:
    453 
    454     if (WalkState)
    455     {
    456         ACPI_ERROR ((AE_INFO,
    457             "Invalid/unsupported resource descriptor: Type 0x%2.2X",
    458             ResourceType));
    459     }
    460     return (AE_AML_INVALID_RESOURCE_TYPE);
    461 
    462 BadResourceLength:
    463 
    464     if (WalkState)
    465     {
    466         ACPI_ERROR ((AE_INFO,
    467             "Invalid resource descriptor length: Type "
    468             "0x%2.2X, Length 0x%4.4X, MinLength 0x%4.4X",
    469             ResourceType, ResourceLength, MinimumResourceLength));
    470     }
    471     return (AE_AML_BAD_RESOURCE_LENGTH);
    472 }
    473 
    474 
    475 /*******************************************************************************
    476  *
    477  * FUNCTION:    AcpiUtGetResourceType
    478  *
    479  * PARAMETERS:  Aml             - Pointer to the raw AML resource descriptor
    480  *
    481  * RETURN:      The Resource Type with no extraneous bits (except the
    482  *              Large/Small descriptor bit -- this is left alone)
    483  *
    484  * DESCRIPTION: Extract the Resource Type/Name from the first byte of
    485  *              a resource descriptor.
    486  *
    487  ******************************************************************************/
    488 
    489 UINT8
    490 AcpiUtGetResourceType (
    491     void                    *Aml)
    492 {
    493     ACPI_FUNCTION_ENTRY ();
    494 
    495 
    496     /*
    497      * Byte 0 contains the descriptor name (Resource Type)
    498      * Examine the large/small bit in the resource header
    499      */
    500     if (ACPI_GET8 (Aml) & ACPI_RESOURCE_NAME_LARGE)
    501     {
    502         /* Large Resource Type -- bits 6:0 contain the name */
    503 
    504         return (ACPI_GET8 (Aml));
    505     }
    506     else
    507     {
    508         /* Small Resource Type -- bits 6:3 contain the name */
    509 
    510         return ((UINT8) (ACPI_GET8 (Aml) & ACPI_RESOURCE_NAME_SMALL_MASK));
    511     }
    512 }
    513 
    514 
    515 /*******************************************************************************
    516  *
    517  * FUNCTION:    AcpiUtGetResourceLength
    518  *
    519  * PARAMETERS:  Aml             - Pointer to the raw AML resource descriptor
    520  *
    521  * RETURN:      Byte Length
    522  *
    523  * DESCRIPTION: Get the "Resource Length" of a raw AML descriptor. By
    524  *              definition, this does not include the size of the descriptor
    525  *              header or the length field itself.
    526  *
    527  ******************************************************************************/
    528 
    529 UINT16
    530 AcpiUtGetResourceLength (
    531     void                    *Aml)
    532 {
    533     ACPI_RS_LENGTH          ResourceLength;
    534 
    535 
    536     ACPI_FUNCTION_ENTRY ();
    537 
    538 
    539     /*
    540      * Byte 0 contains the descriptor name (Resource Type)
    541      * Examine the large/small bit in the resource header
    542      */
    543     if (ACPI_GET8 (Aml) & ACPI_RESOURCE_NAME_LARGE)
    544     {
    545         /* Large Resource type -- bytes 1-2 contain the 16-bit length */
    546 
    547         ACPI_MOVE_16_TO_16 (&ResourceLength, ACPI_ADD_PTR (UINT8, Aml, 1));
    548 
    549     }
    550     else
    551     {
    552         /* Small Resource type -- bits 2:0 of byte 0 contain the length */
    553 
    554         ResourceLength = (UINT16) (ACPI_GET8 (Aml) &
    555             ACPI_RESOURCE_NAME_SMALL_LENGTH_MASK);
    556     }
    557 
    558     return (ResourceLength);
    559 }
    560 
    561 
    562 /*******************************************************************************
    563  *
    564  * FUNCTION:    AcpiUtGetResourceHeaderLength
    565  *
    566  * PARAMETERS:  Aml             - Pointer to the raw AML resource descriptor
    567  *
    568  * RETURN:      Length of the AML header (depends on large/small descriptor)
    569  *
    570  * DESCRIPTION: Get the length of the header for this resource.
    571  *
    572  ******************************************************************************/
    573 
    574 UINT8
    575 AcpiUtGetResourceHeaderLength (
    576     void                    *Aml)
    577 {
    578     ACPI_FUNCTION_ENTRY ();
    579 
    580 
    581     /* Examine the large/small bit in the resource header */
    582 
    583     if (ACPI_GET8 (Aml) & ACPI_RESOURCE_NAME_LARGE)
    584     {
    585         return (sizeof (AML_RESOURCE_LARGE_HEADER));
    586     }
    587     else
    588     {
    589         return (sizeof (AML_RESOURCE_SMALL_HEADER));
    590     }
    591 }
    592 
    593 
    594 /*******************************************************************************
    595  *
    596  * FUNCTION:    AcpiUtGetDescriptorLength
    597  *
    598  * PARAMETERS:  Aml             - Pointer to the raw AML resource descriptor
    599  *
    600  * RETURN:      Byte length
    601  *
    602  * DESCRIPTION: Get the total byte length of a raw AML descriptor, including the
    603  *              length of the descriptor header and the length field itself.
    604  *              Used to walk descriptor lists.
    605  *
    606  ******************************************************************************/
    607 
    608 UINT32
    609 AcpiUtGetDescriptorLength (
    610     void                    *Aml)
    611 {
    612     ACPI_FUNCTION_ENTRY ();
    613 
    614 
    615     /*
    616      * Get the Resource Length (does not include header length) and add
    617      * the header length (depends on if this is a small or large resource)
    618      */
    619     return (AcpiUtGetResourceLength (Aml) +
    620         AcpiUtGetResourceHeaderLength (Aml));
    621 }
    622 
    623 
    624 /*******************************************************************************
    625  *
    626  * FUNCTION:    AcpiUtGetResourceEndTag
    627  *
    628  * PARAMETERS:  ObjDesc         - The resource template buffer object
    629  *              EndTag          - Where the pointer to the EndTag is returned
    630  *
    631  * RETURN:      Status, pointer to the end tag
    632  *
    633  * DESCRIPTION: Find the EndTag resource descriptor in an AML resource template
    634  *              Note: allows a buffer length of zero.
    635  *
    636  ******************************************************************************/
    637 
    638 ACPI_STATUS
    639 AcpiUtGetResourceEndTag (
    640     ACPI_OPERAND_OBJECT     *ObjDesc,
    641     UINT8                   **EndTag)
    642 {
    643     ACPI_STATUS             Status;
    644 
    645 
    646     ACPI_FUNCTION_TRACE (UtGetResourceEndTag);
    647 
    648 
    649     /* Allow a buffer length of zero */
    650 
    651     if (!ObjDesc->Buffer.Length)
    652     {
    653         *EndTag = ObjDesc->Buffer.Pointer;
    654         return_ACPI_STATUS (AE_OK);
    655     }
    656 
    657     /* Validate the template and get a pointer to the EndTag */
    658 
    659     Status = AcpiUtWalkAmlResources (NULL, ObjDesc->Buffer.Pointer,
    660         ObjDesc->Buffer.Length, NULL, (void **) EndTag);
    661 
    662     return_ACPI_STATUS (Status);
    663 }
    664