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dsutils.c

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

/*
 * Copyright (C) 2000 - 2007, R. Byron Moore
 * 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 <acpi/acparser.h>
#include <acpi/amlcode.h>
#include <acpi/acdispat.h>
#include <acpi/acinterp.h>
#include <acpi/acnamesp.h>
#include <acpi/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)) {
                  /*
                   * 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)) {
            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) {
                  /*
                   * 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) {
                  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_from_bottom(&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;
      u32 arg_count = 0;

      ACPI_FUNCTION_TRACE_PTR(ds_create_operands, first_arg);

      /* For all arguments in the list... */

      arg = first_arg;
      while (arg) {
            status = acpi_ds_create_operand(walk_state, arg, arg_count);
            if (ACPI_FAILURE(status)) {
                  goto cleanup;
            }

            ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH,
                          "Arg #%d (%p) done, Arg1=%p\n", arg_count,
                          arg, first_arg));

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

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

      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
       */
      (void)acpi_ds_obj_stack_pop_and_delete(arg_count, walk_state);

      ACPI_EXCEPTION((AE_INFO, status, "While creating Arg %d",
                  (arg_count + 1)));
      return_ACPI_STATUS(status);
}

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