dsutils.c

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/*******************************************************************************
 *
 * Module Name: dsutils - Dispatcher utilities
 *
 ******************************************************************************/

/*
 * Copyright (C) 2000 - 2012, Intel Corp.
 * All rights reserved.
 *
 * 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.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * NO WARRANTY
 * 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 MERCHANTIBILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR 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 DAMAGES.
 */

#include <acpi/acpi.h>
#include "accommon.h"
#include "acparser.h"
#include "amlcode.h"
#include "acdispat.h"
#include "acinterp.h"
#include "acnamesp.h"
#include "acdebug.h"

#define _COMPONENT          ACPI_DISPATCHER
ACPI_MODULE_NAME("dsutils")

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_clear_implicit_return
 *
 * PARAMETERS:  walk_state          - Current State
 *
 * RETURN:      None.
 *
 * DESCRIPTION: Clear and remove a reference on an implicit return value.  Used
 *              to delete "stale" return values (if enabled, the return value
 *              from every operator is saved at least momentarily, in case the
 *              parent method exits.)
 *
 ******************************************************************************/
void acpi_ds_clear_implicit_return(struct acpi_walk_state *walk_state)
{
    ACPI_FUNCTION_NAME(ds_clear_implicit_return);

    /*
     * Slack must be enabled for this feature
     */
    if (!acpi_gbl_enable_interpreter_slack) {
        return;
    }

    if (walk_state->implicit_return_obj) {
        /*
         * Delete any "stale" implicit return. However, in
         * complex statements, the implicit return value can be
         * bubbled up several levels.
         */
        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                  "Removing reference on stale implicit return obj %p\n",
                  walk_state->implicit_return_obj));

        acpi_ut_remove_reference(walk_state->implicit_return_obj);
        walk_state->implicit_return_obj = NULL;
    }
}

#ifndef ACPI_NO_METHOD_EXECUTION
/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_do_implicit_return
 *
 * PARAMETERS:  return_desc         - The return value
 *              walk_state          - Current State
 *              add_reference       - True if a reference should be added to the
 *                                    return object
 *
 * RETURN:      TRUE if implicit return enabled, FALSE otherwise
 *
 * DESCRIPTION: Implements the optional "implicit return".  We save the result
 *              of every ASL operator and control method invocation in case the
 *              parent method exit.  Before storing a new return value, we
 *              delete the previous return value.
 *
 ******************************************************************************/

u8
acpi_ds_do_implicit_return(union acpi_operand_object *return_desc,
               struct acpi_walk_state *walk_state, u8 add_reference)
{
    ACPI_FUNCTION_NAME(ds_do_implicit_return);

    /*
     * Slack must be enabled for this feature, and we must
     * have a valid return object
     */
    if ((!acpi_gbl_enable_interpreter_slack) || (!return_desc)) {
        return (FALSE);
    }

    ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
              "Result %p will be implicitly returned; Prev=%p\n",
              return_desc, walk_state->implicit_return_obj));

    /*
     * Delete any "stale" implicit return value first. However, in
     * complex statements, the implicit return value can be
     * bubbled up several levels, so we don't clear the value if it
     * is the same as the return_desc.
     */
    if (walk_state->implicit_return_obj) {
        if (walk_state->implicit_return_obj == return_desc) {
            return (TRUE);
        }
        acpi_ds_clear_implicit_return(walk_state);
    }

    /* Save the implicit return value, add a reference if requested */

    walk_state->implicit_return_obj = return_desc;
    if (add_reference) {
        acpi_ut_add_reference(return_desc);
    }

    return (TRUE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_is_result_used
 *
 * PARAMETERS:  op                  - Current Op
 *              walk_state          - Current State
 *
 * RETURN:      TRUE if result is used, FALSE otherwise
 *
 * DESCRIPTION: Check if a result object will be used by the parent
 *
 ******************************************************************************/

u8
acpi_ds_is_result_used(union acpi_parse_object * op,
               struct acpi_walk_state * walk_state)
{
    const struct acpi_opcode_info *parent_info;

    ACPI_FUNCTION_TRACE_PTR(ds_is_result_used, op);

    /* Must have both an Op and a Result Object */

    if (!op) {
        ACPI_ERROR((AE_INFO, "Null Op"));
        return_UINT8(TRUE);
    }

    /*
     * We know that this operator is not a
     * Return() operator (would not come here.) The following code is the
     * optional support for a so-called "implicit return". Some AML code
     * assumes that the last value of the method is "implicitly" returned
     * to the caller. Just save the last result as the return value.
     * NOTE: this is optional because the ASL language does not actually
     * support this behavior.
     */
    (void)acpi_ds_do_implicit_return(walk_state->result_obj, walk_state,
                     TRUE);

    /*
     * Now determine if the parent will use the result
     *
     * If there is no parent, or the parent is a scope_op, we are executing
     * at the method level. An executing method typically has no parent,
     * since each method is parsed separately.  A method invoked externally
     * via execute_control_method has a scope_op as the parent.
     */
    if ((!op->common.parent) ||
        (op->common.parent->common.aml_opcode == AML_SCOPE_OP)) {

        /* No parent, the return value cannot possibly be used */

        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                  "At Method level, result of [%s] not used\n",
                  acpi_ps_get_opcode_name(op->common.
                              aml_opcode)));
        return_UINT8(FALSE);
    }

    /* Get info on the parent. The root_op is AML_SCOPE */

    parent_info =
        acpi_ps_get_opcode_info(op->common.parent->common.aml_opcode);
    if (parent_info->class == AML_CLASS_UNKNOWN) {
        ACPI_ERROR((AE_INFO, "Unknown parent opcode Op=%p", op));
        return_UINT8(FALSE);
    }

    /*
     * Decide what to do with the result based on the parent.  If
     * the parent opcode will not use the result, delete the object.
     * Otherwise leave it as is, it will be deleted when it is used
     * as an operand later.
     */
    switch (parent_info->class) {
    case AML_CLASS_CONTROL:

        switch (op->common.parent->common.aml_opcode) {
        case AML_RETURN_OP:

            /* Never delete the return value associated with a return opcode */

            goto result_used;

        case AML_IF_OP:
        case AML_WHILE_OP:

            /*
             * If we are executing the predicate AND this is the predicate op,
             * we will use the return value
             */
            if ((walk_state->control_state->common.state ==
                 ACPI_CONTROL_PREDICATE_EXECUTING)
                && (walk_state->control_state->control.
                predicate_op == op)) {
                goto result_used;
            }
            break;

        default:
            /* Ignore other control opcodes */
            break;
        }

        /* The general control opcode returns no result */

        goto result_not_used;

    case AML_CLASS_CREATE:

        /*
         * These opcodes allow term_arg(s) as operands and therefore
         * the operands can be method calls.  The result is used.
         */
        goto result_used;

    case AML_CLASS_NAMED_OBJECT:

        if ((op->common.parent->common.aml_opcode == AML_REGION_OP) ||
            (op->common.parent->common.aml_opcode == AML_DATA_REGION_OP)
            || (op->common.parent->common.aml_opcode == AML_PACKAGE_OP)
            || (op->common.parent->common.aml_opcode ==
            AML_VAR_PACKAGE_OP)
            || (op->common.parent->common.aml_opcode == AML_BUFFER_OP)
            || (op->common.parent->common.aml_opcode ==
            AML_INT_EVAL_SUBTREE_OP)
            || (op->common.parent->common.aml_opcode ==
            AML_BANK_FIELD_OP)) {
            /*
             * These opcodes allow term_arg(s) as operands and therefore
             * the operands can be method calls.  The result is used.
             */
            goto result_used;
        }

        goto result_not_used;

    default:

        /*
         * In all other cases. the parent will actually use the return
         * object, so keep it.
         */
        goto result_used;
    }

      result_used:
    ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
              "Result of [%s] used by Parent [%s] Op=%p\n",
              acpi_ps_get_opcode_name(op->common.aml_opcode),
              acpi_ps_get_opcode_name(op->common.parent->common.
                          aml_opcode), op));

    return_UINT8(TRUE);

      result_not_used:
    ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
              "Result of [%s] not used by Parent [%s] Op=%p\n",
              acpi_ps_get_opcode_name(op->common.aml_opcode),
              acpi_ps_get_opcode_name(op->common.parent->common.
                          aml_opcode), op));

    return_UINT8(FALSE);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_delete_result_if_not_used
 *
 * PARAMETERS:  op              - Current parse Op
 *              result_obj      - Result of the operation
 *              walk_state      - Current state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Used after interpretation of an opcode.  If there is an internal
 *              result descriptor, check if the parent opcode will actually use
 *              this result.  If not, delete the result now so that it will
 *              not become orphaned.
 *
 ******************************************************************************/

void
acpi_ds_delete_result_if_not_used(union acpi_parse_object *op,
                  union acpi_operand_object *result_obj,
                  struct acpi_walk_state *walk_state)
{
    union acpi_operand_object *obj_desc;
    acpi_status status;

    ACPI_FUNCTION_TRACE_PTR(ds_delete_result_if_not_used, result_obj);

    if (!op) {
        ACPI_ERROR((AE_INFO, "Null Op"));
        return_VOID;
    }

    if (!result_obj) {
        return_VOID;
    }

    if (!acpi_ds_is_result_used(op, walk_state)) {

        /* Must pop the result stack (obj_desc should be equal to result_obj) */

        status = acpi_ds_result_pop(&obj_desc, walk_state);
        if (ACPI_SUCCESS(status)) {
            acpi_ut_remove_reference(result_obj);
        }
    }

    return_VOID;
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_resolve_operands
 *
 * PARAMETERS:  walk_state          - Current walk state with operands on stack
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Resolve all operands to their values.  Used to prepare
 *              arguments to a control method invocation (a call from one
 *              method to another.)
 *
 ******************************************************************************/

acpi_status acpi_ds_resolve_operands(struct acpi_walk_state *walk_state)
{
    u32 i;
    acpi_status status = AE_OK;

    ACPI_FUNCTION_TRACE_PTR(ds_resolve_operands, walk_state);

    /*
     * Attempt to resolve each of the valid operands
     * Method arguments are passed by reference, not by value.  This means
     * that the actual objects are passed, not copies of the objects.
     */
    for (i = 0; i < walk_state->num_operands; i++) {
        status =
            acpi_ex_resolve_to_value(&walk_state->operands[i],
                         walk_state);
        if (ACPI_FAILURE(status)) {
            break;
        }
    }

    return_ACPI_STATUS(status);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_clear_operands
 *
 * PARAMETERS:  walk_state          - Current walk state with operands on stack
 *
 * RETURN:      None
 *
 * DESCRIPTION: Clear all operands on the current walk state operand stack.
 *
 ******************************************************************************/

void acpi_ds_clear_operands(struct acpi_walk_state *walk_state)
{
    u32 i;

    ACPI_FUNCTION_TRACE_PTR(ds_clear_operands, walk_state);

    /* Remove a reference on each operand on the stack */

    for (i = 0; i < walk_state->num_operands; i++) {
        /*
         * Remove a reference to all operands, including both
         * "Arguments" and "Targets".
         */
        acpi_ut_remove_reference(walk_state->operands[i]);
        walk_state->operands[i] = NULL;
    }

    walk_state->num_operands = 0;
    return_VOID;
}
#endif

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_create_operand
 *
 * PARAMETERS:  walk_state      - Current walk state
 *              arg             - Parse object for the argument
 *              arg_index       - Which argument (zero based)
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Translate a parse tree object that is an argument to an AML
 *              opcode to the equivalent interpreter object.  This may include
 *              looking up a name or entering a new name into the internal
 *              namespace.
 *
 ******************************************************************************/

acpi_status
acpi_ds_create_operand(struct acpi_walk_state *walk_state,
               union acpi_parse_object *arg, u32 arg_index)
{
    acpi_status status = AE_OK;
    char *name_string;
    u32 name_length;
    union acpi_operand_object *obj_desc;
    union acpi_parse_object *parent_op;
    u16 opcode;
    acpi_interpreter_mode interpreter_mode;
    const struct acpi_opcode_info *op_info;

    ACPI_FUNCTION_TRACE_PTR(ds_create_operand, arg);

    /* A valid name must be looked up in the namespace */

    if ((arg->common.aml_opcode == AML_INT_NAMEPATH_OP) &&
        (arg->common.value.string) &&
        !(arg->common.flags & ACPI_PARSEOP_IN_STACK)) {
        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "Getting a name: Arg=%p\n",
                  arg));

        /* Get the entire name string from the AML stream */

        status =
            acpi_ex_get_name_string(ACPI_TYPE_ANY,
                        arg->common.value.buffer,
                        &name_string, &name_length);

        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }

        /* All prefixes have been handled, and the name is in name_string */

        /*
         * Special handling for buffer_field declarations. This is a deferred
         * opcode that unfortunately defines the field name as the last
         * parameter instead of the first.  We get here when we are performing
         * the deferred execution, so the actual name of the field is already
         * in the namespace.  We don't want to attempt to look it up again
         * because we may be executing in a different scope than where the
         * actual opcode exists.
         */
        if ((walk_state->deferred_node) &&
            (walk_state->deferred_node->type == ACPI_TYPE_BUFFER_FIELD)
            && (arg_index ==
            (u32) ((walk_state->opcode ==
                AML_CREATE_FIELD_OP) ? 3 : 2))) {
            obj_desc =
                ACPI_CAST_PTR(union acpi_operand_object,
                      walk_state->deferred_node);
            status = AE_OK;
        } else {    /* All other opcodes */

            /*
             * Differentiate between a namespace "create" operation
             * versus a "lookup" operation (IMODE_LOAD_PASS2 vs.
             * IMODE_EXECUTE) in order to support the creation of
             * namespace objects during the execution of control methods.
             */
            parent_op = arg->common.parent;
            op_info =
                acpi_ps_get_opcode_info(parent_op->common.
                            aml_opcode);
            if ((op_info->flags & AML_NSNODE)
                && (parent_op->common.aml_opcode !=
                AML_INT_METHODCALL_OP)
                && (parent_op->common.aml_opcode != AML_REGION_OP)
                && (parent_op->common.aml_opcode !=
                AML_INT_NAMEPATH_OP)) {

                /* Enter name into namespace if not found */

                interpreter_mode = ACPI_IMODE_LOAD_PASS2;
            } else {
                /* Return a failure if name not found */

                interpreter_mode = ACPI_IMODE_EXECUTE;
            }

            status =
                acpi_ns_lookup(walk_state->scope_info, name_string,
                       ACPI_TYPE_ANY, interpreter_mode,
                       ACPI_NS_SEARCH_PARENT |
                       ACPI_NS_DONT_OPEN_SCOPE, walk_state,
                       ACPI_CAST_INDIRECT_PTR(struct
                                  acpi_namespace_node,
                                  &obj_desc));
            /*
             * The only case where we pass through (ignore) a NOT_FOUND
             * error is for the cond_ref_of opcode.
             */
            if (status == AE_NOT_FOUND) {
                if (parent_op->common.aml_opcode ==
                    AML_COND_REF_OF_OP) {
                    /*
                     * For the Conditional Reference op, it's OK if
                     * the name is not found;  We just need a way to
                     * indicate this to the interpreter, set the
                     * object to the root
                     */
                    obj_desc = ACPI_CAST_PTR(union
                                 acpi_operand_object,
                                 acpi_gbl_root_node);
                    status = AE_OK;
                } else {
                    /*
                     * We just plain didn't find it -- which is a
                     * very serious error at this point
                     */
                    status = AE_AML_NAME_NOT_FOUND;
                }
            }

            if (ACPI_FAILURE(status)) {
                ACPI_ERROR_NAMESPACE(name_string, status);
            }
        }

        /* Free the namestring created above */

        ACPI_FREE(name_string);

        /* Check status from the lookup */

        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }

        /* Put the resulting object onto the current object stack */

        status = acpi_ds_obj_stack_push(obj_desc, walk_state);
        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }
        ACPI_DEBUGGER_EXEC(acpi_db_display_argument_object
                   (obj_desc, walk_state));
    } else {
        /* Check for null name case */

        if ((arg->common.aml_opcode == AML_INT_NAMEPATH_OP) &&
            !(arg->common.flags & ACPI_PARSEOP_IN_STACK)) {
            /*
             * If the name is null, this means that this is an
             * optional result parameter that was not specified
             * in the original ASL.  Create a Zero Constant for a
             * placeholder.  (Store to a constant is a Noop.)
             */
            opcode = AML_ZERO_OP;   /* Has no arguments! */

            ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                      "Null namepath: Arg=%p\n", arg));
        } else {
            opcode = arg->common.aml_opcode;
        }

        /* Get the object type of the argument */

        op_info = acpi_ps_get_opcode_info(opcode);
        if (op_info->object_type == ACPI_TYPE_INVALID) {
            return_ACPI_STATUS(AE_NOT_IMPLEMENTED);
        }

        if ((op_info->flags & AML_HAS_RETVAL)
            || (arg->common.flags & ACPI_PARSEOP_IN_STACK)) {
            ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                      "Argument previously created, already stacked\n"));

            ACPI_DEBUGGER_EXEC(acpi_db_display_argument_object
                       (walk_state->
                        operands[walk_state->num_operands -
                             1], walk_state));

            /*
             * Use value that was already previously returned
             * by the evaluation of this argument
             */
            status = acpi_ds_result_pop(&obj_desc, walk_state);
            if (ACPI_FAILURE(status)) {
                /*
                 * Only error is underflow, and this indicates
                 * a missing or null operand!
                 */
                ACPI_EXCEPTION((AE_INFO, status,
                        "Missing or null operand"));
                return_ACPI_STATUS(status);
            }
        } else {
            /* Create an ACPI_INTERNAL_OBJECT for the argument */

            obj_desc =
                acpi_ut_create_internal_object(op_info->
                               object_type);
            if (!obj_desc) {
                return_ACPI_STATUS(AE_NO_MEMORY);
            }

            /* Initialize the new object */

            status =
                acpi_ds_init_object_from_op(walk_state, arg, opcode,
                            &obj_desc);
            if (ACPI_FAILURE(status)) {
                acpi_ut_delete_object_desc(obj_desc);
                return_ACPI_STATUS(status);
            }
        }

        /* Put the operand object on the object stack */

        status = acpi_ds_obj_stack_push(obj_desc, walk_state);
        if (ACPI_FAILURE(status)) {
            return_ACPI_STATUS(status);
        }

        ACPI_DEBUGGER_EXEC(acpi_db_display_argument_object
                   (obj_desc, walk_state));
    }

    return_ACPI_STATUS(AE_OK);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ds_create_operands
 *
 * PARAMETERS:  walk_state          - Current state
 *              first_arg           - First argument of a parser argument tree
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Convert an operator's arguments from a parse tree format to
 *              namespace objects and place those argument object on the object
 *              stack in preparation for evaluation by the interpreter.
 *
 ******************************************************************************/

acpi_status
acpi_ds_create_operands(struct acpi_walk_state *walk_state,
            union acpi_parse_object *first_arg)
{
    acpi_status status = AE_OK;
    union acpi_parse_object *arg;
    union acpi_parse_object *arguments[ACPI_OBJ_NUM_OPERANDS];
    u32 arg_count = 0;
    u32 index = walk_state->num_operands;
    u32 i;

    ACPI_FUNCTION_TRACE_PTR(ds_create_operands, first_arg);

    /* Get all arguments in the list */

    arg = first_arg;
    while (arg) {
        if (index >= ACPI_OBJ_NUM_OPERANDS) {
            return_ACPI_STATUS(AE_BAD_DATA);
        }

        arguments[index] = arg;
        walk_state->operands[index] = NULL;

        /* Move on to next argument, if any */

        arg = arg->common.next;
        arg_count++;
        index++;
    }

    index--;

    /* It is the appropriate order to get objects from the Result stack */

    for (i = 0; i < arg_count; i++) {
        arg = arguments[index];

        /* Force the filling of the operand stack in inverse order */

        walk_state->operand_index = (u8) index;

        status = acpi_ds_create_operand(walk_state, arg, index);
        if (ACPI_FAILURE(status)) {
            goto cleanup;
        }

        index--;

        ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                  "Arg #%u (%p) done, Arg1=%p\n", index, arg,
                  first_arg));
    }

    return_ACPI_STATUS(status);

      cleanup:
    /*
     * We must undo everything done above; meaning that we must
     * pop everything off of the operand stack and delete those
     * objects
     */
    acpi_ds_obj_stack_pop_and_delete(arg_count, walk_state);

    ACPI_EXCEPTION((AE_INFO, status, "While creating Arg %u", index));
    return_ACPI_STATUS(status);
}

/*****************************************************************************
 *
 * FUNCTION:    acpi_ds_evaluate_name_path
 *
 * PARAMETERS:  walk_state      - Current state of the parse tree walk,
 *                                the opcode of current operation should be
 *                                AML_INT_NAMEPATH_OP
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Translate the -name_path- parse tree object to the equivalent
 *              interpreter object, convert it to value, if needed, duplicate
 *              it, if needed, and push it onto the current result stack.
 *
 ****************************************************************************/

acpi_status acpi_ds_evaluate_name_path(struct acpi_walk_state *walk_state)
{
    acpi_status status = AE_OK;
    union acpi_parse_object *op = walk_state->op;
    union acpi_operand_object **operand = &walk_state->operands[0];
    union acpi_operand_object *new_obj_desc;
    u8 type;

    ACPI_FUNCTION_TRACE_PTR(ds_evaluate_name_path, walk_state);

    if (!op->common.parent) {

        /* This happens after certain exception processing */

        goto exit;
    }

    if ((op->common.parent->common.aml_opcode == AML_PACKAGE_OP) ||
        (op->common.parent->common.aml_opcode == AML_VAR_PACKAGE_OP) ||
        (op->common.parent->common.aml_opcode == AML_REF_OF_OP)) {

        /* TBD: Should we specify this feature as a bit of op_info->Flags of these opcodes? */

        goto exit;
    }

    status = acpi_ds_create_operand(walk_state, op, 0);
    if (ACPI_FAILURE(status)) {
        goto exit;
    }

    if (op->common.flags & ACPI_PARSEOP_TARGET) {
        new_obj_desc = *operand;
        goto push_result;
    }

    type = (*operand)->common.type;

    status = acpi_ex_resolve_to_value(operand, walk_state);
    if (ACPI_FAILURE(status)) {
        goto exit;
    }

    if (type == ACPI_TYPE_INTEGER) {

        /* It was incremented by acpi_ex_resolve_to_value */

        acpi_ut_remove_reference(*operand);

        status =
            acpi_ut_copy_iobject_to_iobject(*operand, &new_obj_desc,
                            walk_state);
        if (ACPI_FAILURE(status)) {
            goto exit;
        }
    } else {
        /*
         * The object either was anew created or is
         * a Namespace node - don't decrement it.
         */
        new_obj_desc = *operand;
    }

    /* Cleanup for name-path operand */

    status = acpi_ds_obj_stack_pop(1, walk_state);
    if (ACPI_FAILURE(status)) {
        walk_state->result_obj = new_obj_desc;
        goto exit;
    }

      push_result:

    walk_state->result_obj = new_obj_desc;

    status = acpi_ds_result_push(walk_state->result_obj, walk_state);
    if (ACPI_SUCCESS(status)) {

        /* Force to take it from stack */

        op->common.flags |= ACPI_PARSEOP_IN_STACK;
    }

      exit:

    return_ACPI_STATUS(status);
}