dsutils.c

h内核

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

/*
 * Copyright (C) 2000 - 2005, 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")


#ifndef ACPI_NO_METHOD_EXECUTION

/*******************************************************************************
 *
 * 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_DEBUG_PRINT ((ACPI_DB_ERROR, "Null Op\n"));
		return_VALUE (TRUE);
	}

	/*
	 * 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)) {
		/*
		 * If this is the last statement in the method, we know it 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.
		 */
		if ((acpi_gbl_enable_interpreter_slack) &&
			(walk_state->parser_state.aml >= walk_state->parser_state.aml_end)) {
			ACPI_DEBUG_PRINT ((ACPI_DB_DISPATCH,
					"Result of [%s] will be implicitly returned\n",
					acpi_ps_get_opcode_name (op->common.aml_opcode)));

			/* Use the top of the result stack as the implicit return value */

			walk_state->return_desc = walk_state->results->results.obj_desc[0];
			return_VALUE (TRUE);
		}

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

		return_VALUE (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_DEBUG_PRINT ((ACPI_DB_ERROR, "Unknown parent opcode. Op=%p\n", op));
		return_VALUE (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_VALUE (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_VALUE (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_DEBUG_PRINT ((ACPI_DB_ERROR, "Null Op\n"));
		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
 *