drivers/acpi/acpica/psparse.c - kernel/msm-4.9 - Gitiles

 /******************************************************************************
  *
  * Module Name: psparse - Parser top level AML parse routines
  *
  *****************************************************************************/

 /*
  * 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.
  */

 /*
  * Parse the AML and build an operation tree as most interpreters,
  * like Perl, do.  Parsing is done by hand rather than with a YACC
  * generated parser to tightly constrain stack and dynamic memory
  * usage.  At the same time, parsing is kept flexible and the code
  * fairly compact by parsing based on a list of AML opcode
  * templates in aml_op_info[]
  */

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

 #define _COMPONENT          ACPI_PARSER
 ACPI_MODULE_NAME("psparse")

 /*******************************************************************************
  *
  * FUNCTION:    acpi_ps_get_opcode_size
  *
  * PARAMETERS:  Opcode          - An AML opcode
  *
  * RETURN:      Size of the opcode, in bytes (1 or 2)
  *
  * DESCRIPTION: Get the size of the current opcode.
  *
  ******************************************************************************/
 u32 acpi_ps_get_opcode_size(u32 opcode)
 {

 	/* Extended (2-byte) opcode if > 255 */

 	if (opcode > 0x00FF) {
 		return (2);
 	}

 	/* Otherwise, just a single byte opcode */

 	return (1);
 }

 /*******************************************************************************
  *
  * FUNCTION:    acpi_ps_peek_opcode
  *
  * PARAMETERS:  parser_state        - A parser state object
  *
  * RETURN:      Next AML opcode
  *
  * DESCRIPTION: Get next AML opcode (without incrementing AML pointer)
  *
  ******************************************************************************/

 u16 acpi_ps_peek_opcode(struct acpi_parse_state * parser_state)
 {
 	u8 *aml;
 	u16 opcode;

 	aml = parser_state->aml;
 	opcode = (u16) ACPI_GET8(aml);

 	if (opcode == AML_EXTENDED_OP_PREFIX) {

 		/* Extended opcode, get the second opcode byte */

 		aml++;
 		opcode = (u16) ((opcode << 8) | ACPI_GET8(aml));
 	}

 	return (opcode);
 }

 /*******************************************************************************
  *
  * FUNCTION:    acpi_ps_complete_this_op
  *
  * PARAMETERS:  walk_state      - Current State
  *              Op              - Op to complete
  *
  * RETURN:      Status
  *
  * DESCRIPTION: Perform any cleanup at the completion of an Op.
  *
  ******************************************************************************/

 acpi_status
 acpi_ps_complete_this_op(struct acpi_walk_state * walk_state,
 			 union acpi_parse_object * op)
 {
 	union acpi_parse_object *prev;
 	union acpi_parse_object *next;
 	const struct acpi_opcode_info *parent_info;
 	union acpi_parse_object *replacement_op = NULL;
 	acpi_status status = AE_OK;

 	ACPI_FUNCTION_TRACE_PTR(ps_complete_this_op, op);

 	/* Check for null Op, can happen if AML code is corrupt */

 	if (!op) {
 		return_ACPI_STATUS(AE_OK);	/* OK for now */
 	}

 	/* Delete this op and the subtree below it if asked to */

 	if (((walk_state->parse_flags & ACPI_PARSE_TREE_MASK) !=
 	     ACPI_PARSE_DELETE_TREE)
 	    || (walk_state->op_info->class == AML_CLASS_ARGUMENT)) {
 		return_ACPI_STATUS(AE_OK);
 	}

 	/* Make sure that we only delete this subtree */

 	if (op->common.parent) {
 		prev = op->common.parent->common.value.arg;
 		if (!prev) {

 			/* Nothing more to do */

 			goto cleanup;
 		}

 		/*
 		 * Check if we need to replace the operator and its subtree
 		 * with a return value op (placeholder op)
 		 */
 		parent_info =
 		    acpi_ps_get_opcode_info(op->common.parent->common.
 					    aml_opcode);

 		switch (parent_info->class) {
 		case AML_CLASS_CONTROL:
 			break;

 		case AML_CLASS_CREATE:

 			/*
 			 * These opcodes contain term_arg operands. The current
 			 * op must be replaced by a placeholder return op
 			 */
 			replacement_op =
 			    acpi_ps_alloc_op(AML_INT_RETURN_VALUE_OP);
 			if (!replacement_op) {
 				status = AE_NO_MEMORY;
 			}
 			break;

 		case AML_CLASS_NAMED_OBJECT:

 			/*
 			 * These opcodes contain term_arg operands. The current
 			 * op must be replaced by a placeholder return op
 			 */
 			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_BUFFER_OP)
 			    || (op->common.parent->common.aml_opcode ==
 				AML_PACKAGE_OP)
 			    || (op->common.parent->common.aml_opcode ==
 				AML_BANK_FIELD_OP)
 			    || (op->common.parent->common.aml_opcode ==
 				AML_VAR_PACKAGE_OP)) {
 				replacement_op =
 				    acpi_ps_alloc_op(AML_INT_RETURN_VALUE_OP);
 				if (!replacement_op) {
 					status = AE_NO_MEMORY;
 				}
 			} else
 			    if ((op->common.parent->common.aml_opcode ==
 				 AML_NAME_OP)
 				&& (walk_state->pass_number <=
 				    ACPI_IMODE_LOAD_PASS2)) {
 				if ((op->common.aml_opcode == AML_BUFFER_OP)
 				    || (op->common.aml_opcode == AML_PACKAGE_OP)
 				    || (op->common.aml_opcode ==
 					AML_VAR_PACKAGE_OP)) {
 					replacement_op =
 					    acpi_ps_alloc_op(op->common.
 							     aml_opcode);
 					if (!replacement_op) {
 						status = AE_NO_MEMORY;
 					} else {
 						replacement_op->named.data =
 						    op->named.data;
 						replacement_op->named.length =
 						    op->named.length;
 					}
 				}
 			}
 			break;

 		default:

 			replacement_op =
 			    acpi_ps_alloc_op(AML_INT_RETURN_VALUE_OP);
 			if (!replacement_op) {
 				status = AE_NO_MEMORY;
 			}
 		}

 		/* We must unlink this op from the parent tree */

 		if (prev == op) {

 			/* This op is the first in the list */

 			if (replacement_op) {
 				replacement_op->common.parent =
 				    op->common.parent;
 				replacement_op->common.value.arg = NULL;
 				replacement_op->common.node = op->common.node;
 				op->common.parent->common.value.arg =
 				    replacement_op;
 				replacement_op->common.next = op->common.next;
 			} else {
 				op->common.parent->common.value.arg =
 				    op->common.next;
 			}
 		}

 		/* Search the parent list */

 		else
 			while (prev) {

 				/* Traverse all siblings in the parent's argument list */

 				next = prev->common.next;
 				if (next == op) {
 					if (replacement_op) {
 						replacement_op->common.parent =
 						    op->common.parent;
 						replacement_op->common.value.
 						    arg = NULL;
 						replacement_op->common.node =
 						    op->common.node;
 						prev->common.next =
 						    replacement_op;
 						replacement_op->common.next =
 						    op->common.next;
 						next = NULL;
 					} else {
 						prev->common.next =
 						    op->common.next;
 						next = NULL;
 					}
 				}
 				prev = next;
 			}
 	}

       cleanup:

 	/* Now we can actually delete the subtree rooted at Op */

 	acpi_ps_delete_parse_tree(op);
 	return_ACPI_STATUS(status);
 }

 /*******************************************************************************
  *
  * FUNCTION:    acpi_ps_next_parse_state
  *
  * PARAMETERS:  walk_state          - Current state
  *              Op                  - Current parse op
  *              callback_status     - Status from previous operation
  *
  * RETURN:      Status
  *
  * DESCRIPTION: Update the parser state based upon the return exception from
  *              the parser callback.
  *
  ******************************************************************************/

 acpi_status
 acpi_ps_next_parse_state(struct acpi_walk_state *walk_state,
 			 union acpi_parse_object *op,
 			 acpi_status callback_status)
 {
 	struct acpi_parse_state *parser_state = &walk_state->parser_state;
 	acpi_status status = AE_CTRL_PENDING;

 	ACPI_FUNCTION_TRACE_PTR(ps_next_parse_state, op);

 	switch (callback_status) {
 	case AE_CTRL_TERMINATE:
 		/*
 		 * A control method was terminated via a RETURN statement.
 		 * The walk of this method is complete.
 		 */
 		parser_state->aml = parser_state->aml_end;
 		status = AE_CTRL_TERMINATE;
 		break;

 	case AE_CTRL_BREAK:

 		parser_state->aml = walk_state->aml_last_while;
 		walk_state->control_state->common.value = FALSE;
 		status = AE_CTRL_BREAK;
 		break;

 	case AE_CTRL_CONTINUE:

 		parser_state->aml = walk_state->aml_last_while;
 		status = AE_CTRL_CONTINUE;
 		break;

 	case AE_CTRL_PENDING:

 		parser_state->aml = walk_state->aml_last_while;
 		break;

 #if 0
 	case AE_CTRL_SKIP:

 		parser_state->aml = parser_state->scope->parse_scope.pkg_end;
 		status = AE_OK;
 		break;
 #endif

 	case AE_CTRL_TRUE:
 		/*
 		 * Predicate of an IF was true, and we are at the matching ELSE.
 		 * Just close out this package
 		 */
 		parser_state->aml = acpi_ps_get_next_package_end(parser_state);
 		status = AE_CTRL_PENDING;
 		break;

 	case AE_CTRL_FALSE:
 		/*
 		 * Either an IF/WHILE Predicate was false or we encountered a BREAK
 		 * opcode.  In both cases, we do not execute the rest of the
 		 * package;  We simply close out the parent (finishing the walk of
 		 * this branch of the tree) and continue execution at the parent
 		 * level.
 		 */
 		parser_state->aml = parser_state->scope->parse_scope.pkg_end;

 		/* In the case of a BREAK, just force a predicate (if any) to FALSE */

 		walk_state->control_state->common.value = FALSE;
 		status = AE_CTRL_END;
 		break;

 	case AE_CTRL_TRANSFER:

 		/* A method call (invocation) -- transfer control */

 		status = AE_CTRL_TRANSFER;
 		walk_state->prev_op = op;
 		walk_state->method_call_op = op;
 		walk_state->method_call_node =
 		    (op->common.value.arg)->common.node;

 		/* Will return value (if any) be used by the caller? */

 		walk_state->return_used =
 		    acpi_ds_is_result_used(op, walk_state);
 		break;

 	default:

 		status = callback_status;
 		if ((callback_status & AE_CODE_MASK) == AE_CODE_CONTROL) {
 			status = AE_OK;
 		}
 		break;
 	}

 	return_ACPI_STATUS(status);
 }

 /*******************************************************************************
  *
  * FUNCTION:    acpi_ps_parse_aml
  *
  * PARAMETERS:  walk_state      - Current state
  *
  *
  * RETURN:      Status
  *
  * DESCRIPTION: Parse raw AML and return a tree of ops
  *
  ******************************************************************************/

 acpi_status acpi_ps_parse_aml(struct acpi_walk_state *walk_state)
 {
 	acpi_status status;
 	struct acpi_thread_state *thread;
 	struct acpi_thread_state *prev_walk_list = acpi_gbl_current_walk_list;
 	struct acpi_walk_state *previous_walk_state;

 	ACPI_FUNCTION_TRACE(ps_parse_aml);

 	ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 			  "Entered with WalkState=%p Aml=%p size=%X\n",
 			  walk_state, walk_state->parser_state.aml,
 			  walk_state->parser_state.aml_size));

 	if (!walk_state->parser_state.aml) {
 		return_ACPI_STATUS(AE_NULL_OBJECT);
 	}

 	/* Create and initialize a new thread state */

 	thread = acpi_ut_create_thread_state();
 	if (!thread) {
 		if (walk_state->method_desc) {

 			/* Executing a control method - additional cleanup */

 			acpi_ds_terminate_control_method(
 				walk_state->method_desc, walk_state);
 		}

 		acpi_ds_delete_walk_state(walk_state);
 		return_ACPI_STATUS(AE_NO_MEMORY);
 	}

 	walk_state->thread = thread;

 	/*
 	 * If executing a method, the starting sync_level is this method's
 	 * sync_level
 	 */
 	if (walk_state->method_desc) {
 		walk_state->thread->current_sync_level =
 		    walk_state->method_desc->method.sync_level;
 	}

 	acpi_ds_push_walk_state(walk_state, thread);

 	/*
 	 * This global allows the AML debugger to get a handle to the currently
 	 * executing control method.
 	 */
 	acpi_gbl_current_walk_list = thread;

 	/*
 	 * Execute the walk loop as long as there is a valid Walk State.  This
 	 * handles nested control method invocations without recursion.
 	 */
 	ACPI_DEBUG_PRINT((ACPI_DB_PARSE, "State=%p\n", walk_state));

 	status = AE_OK;
 	while (walk_state) {
 		if (ACPI_SUCCESS(status)) {
 			/*
 			 * The parse_loop executes AML until the method terminates
 			 * or calls another method.
 			 */
 			status = acpi_ps_parse_loop(walk_state);
 		}

 		ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 				  "Completed one call to walk loop, %s State=%p\n",
 				  acpi_format_exception(status), walk_state));

 		if (status == AE_CTRL_TRANSFER) {
 			/*
 			 * A method call was detected.
 			 * Transfer control to the called control method
 			 */
 			status =
 			    acpi_ds_call_control_method(thread, walk_state,
 							NULL);
 			if (ACPI_FAILURE(status)) {
 				status =
 				    acpi_ds_method_error(status, walk_state);
 			}

 			/*
 			 * If the transfer to the new method method call worked, a new walk
 			 * state was created -- get it
 			 */
 			walk_state = acpi_ds_get_current_walk_state(thread);
 			continue;
 		} else if (status == AE_CTRL_TERMINATE) {
 			status = AE_OK;
 		} else if ((status != AE_OK) && (walk_state->method_desc)) {

 			/* Either the method parse or actual execution failed */

 			ACPI_ERROR_METHOD("Method parse/execution failed",
 					  walk_state->method_node, NULL,
 					  status);

 			/* Check for possible multi-thread reentrancy problem */

 			if ((status == AE_ALREADY_EXISTS) &&
 			    (!(walk_state->method_desc->method.
 			       info_flags & ACPI_METHOD_SERIALIZED))) {
 				/*
 				 * Method is not serialized and tried to create an object
 				 * twice. The probable cause is that the method cannot
 				 * handle reentrancy. Mark as "pending serialized" now, and
 				 * then mark "serialized" when the last thread exits.
 				 */
 				walk_state->method_desc->method.info_flags |=
 				    ACPI_METHOD_SERIALIZED_PENDING;
 			}
 		}

 		/* We are done with this walk, move on to the parent if any */

 		walk_state = acpi_ds_pop_walk_state(thread);

 		/* Reset the current scope to the beginning of scope stack */

 		acpi_ds_scope_stack_clear(walk_state);

 		/*
 		 * If we just returned from the execution of a control method or if we
 		 * encountered an error during the method parse phase, there's lots of
 		 * cleanup to do
 		 */
 		if (((walk_state->parse_flags & ACPI_PARSE_MODE_MASK) ==
 		     ACPI_PARSE_EXECUTE) || (ACPI_FAILURE(status))) {
 			acpi_ds_terminate_control_method(walk_state->
 							 method_desc,
 							 walk_state);
 		}

 		/* Delete this walk state and all linked control states */

 		acpi_ps_cleanup_scope(&walk_state->parser_state);
 		previous_walk_state = walk_state;

 		ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
 				  "ReturnValue=%p, ImplicitValue=%p State=%p\n",
 				  walk_state->return_desc,
 				  walk_state->implicit_return_obj, walk_state));

 		/* Check if we have restarted a preempted walk */

 		walk_state = acpi_ds_get_current_walk_state(thread);
 		if (walk_state) {
 			if (ACPI_SUCCESS(status)) {
 				/*
 				 * There is another walk state, restart it.
 				 * If the method return value is not used by the parent,
 				 * The object is deleted
 				 */
 				if (!previous_walk_state->return_desc) {
 					/*
 					 * In slack mode execution, if there is no return value
 					 * we should implicitly return zero (0) as a default value.
 					 */
 					if (acpi_gbl_enable_interpreter_slack &&
 					    !previous_walk_state->
 					    implicit_return_obj) {
 						previous_walk_state->
 						    implicit_return_obj =
 						    acpi_ut_create_integer_object
 						    ((u64) 0);
 						if (!previous_walk_state->
 						    implicit_return_obj) {
 							return_ACPI_STATUS
 							    (AE_NO_MEMORY);
 						}
 					}

 					/* Restart the calling control method */

 					status =
 					    acpi_ds_restart_control_method
 					    (walk_state,
 					     previous_walk_state->
 					     implicit_return_obj);
 				} else {
 					/*
 					 * We have a valid return value, delete any implicit
 					 * return value.
 					 */
 					acpi_ds_clear_implicit_return
 					    (previous_walk_state);

 					status =
 					    acpi_ds_restart_control_method
 					    (walk_state,
 					     previous_walk_state->return_desc);
 				}
 				if (ACPI_SUCCESS(status)) {
 					walk_state->walk_type |=
 					    ACPI_WALK_METHOD_RESTART;
 				}
 			} else {
 				/* On error, delete any return object or implicit return */

 				acpi_ut_remove_reference(previous_walk_state->
 							 return_desc);
 				acpi_ds_clear_implicit_return
 				    (previous_walk_state);
 			}
 		}

 		/*
 		 * Just completed a 1st-level method, save the final internal return
 		 * value (if any)
 		 */
 		else if (previous_walk_state->caller_return_desc) {
 			if (previous_walk_state->implicit_return_obj) {
 				*(previous_walk_state->caller_return_desc) =
 				    previous_walk_state->implicit_return_obj;
 			} else {
 				/* NULL if no return value */

 				*(previous_walk_state->caller_return_desc) =
 				    previous_walk_state->return_desc;
 			}
 		} else {
 			if (previous_walk_state->return_desc) {

 				/* Caller doesn't want it, must delete it */

 				acpi_ut_remove_reference(previous_walk_state->
 							 return_desc);
 			}
 			if (previous_walk_state->implicit_return_obj) {

 				/* Caller doesn't want it, must delete it */

 				acpi_ut_remove_reference(previous_walk_state->
 							 implicit_return_obj);
 			}
 		}

 		acpi_ds_delete_walk_state(previous_walk_state);
 	}

 	/* Normal exit */

 	acpi_ex_release_all_mutexes(thread);
 	acpi_ut_delete_generic_state(ACPI_CAST_PTR
 				     (union acpi_generic_state, thread));
 	acpi_gbl_current_walk_list = prev_walk_list;
 	return_ACPI_STATUS(status);
 }
	/******************************************************************************
	*
	* Module Name: psparse - Parser top level AML parse routines
	*
	*****************************************************************************/

	/*
	* 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.
	*/

	/*
	* Parse the AML and build an operation tree as most interpreters,
	* like Perl, do. Parsing is done by hand rather than with a YACC
	* generated parser to tightly constrain stack and dynamic memory
	* usage. At the same time, parsing is kept flexible and the code
	* fairly compact by parsing based on a list of AML opcode
	* templates in aml_op_info[]
	*/

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

	#define _COMPONENT ACPI_PARSER
	ACPI_MODULE_NAME("psparse")

	/*******************************************************************************
	*
	* FUNCTION: acpi_ps_get_opcode_size
	*
	* PARAMETERS: Opcode - An AML opcode
	*
	* RETURN: Size of the opcode, in bytes (1 or 2)
	*
	* DESCRIPTION: Get the size of the current opcode.
	*
	******************************************************************************/
	u32 acpi_ps_get_opcode_size(u32 opcode)
	{

	/* Extended (2-byte) opcode if > 255 */

	if (opcode > 0x00FF) {
	return (2);
	}

	/* Otherwise, just a single byte opcode */

	return (1);
	}

	/*******************************************************************************
	*
	* FUNCTION: acpi_ps_peek_opcode
	*
	* PARAMETERS: parser_state - A parser state object
	*
	* RETURN: Next AML opcode
	*
	* DESCRIPTION: Get next AML opcode (without incrementing AML pointer)
	*
	******************************************************************************/

	u16 acpi_ps_peek_opcode(struct acpi_parse_state * parser_state)
	{
	u8 *aml;
	u16 opcode;

	aml = parser_state->aml;
	opcode = (u16) ACPI_GET8(aml);

	if (opcode == AML_EXTENDED_OP_PREFIX) {

	/* Extended opcode, get the second opcode byte */

	aml++;
	opcode = (u16) ((opcode << 8) \| ACPI_GET8(aml));
	}

	return (opcode);
	}

	/*******************************************************************************
	*
	* FUNCTION: acpi_ps_complete_this_op
	*
	* PARAMETERS: walk_state - Current State
	* Op - Op to complete
	*
	* RETURN: Status
	*
	* DESCRIPTION: Perform any cleanup at the completion of an Op.
	*
	******************************************************************************/

	acpi_status
	acpi_ps_complete_this_op(struct acpi_walk_state * walk_state,
	union acpi_parse_object * op)
	{
	union acpi_parse_object *prev;
	union acpi_parse_object *next;
	const struct acpi_opcode_info *parent_info;
	union acpi_parse_object *replacement_op = NULL;
	acpi_status status = AE_OK;

	ACPI_FUNCTION_TRACE_PTR(ps_complete_this_op, op);

	/* Check for null Op, can happen if AML code is corrupt */

	if (!op) {
	return_ACPI_STATUS(AE_OK); /* OK for now */
	}

	/* Delete this op and the subtree below it if asked to */

	if (((walk_state->parse_flags & ACPI_PARSE_TREE_MASK) !=
	ACPI_PARSE_DELETE_TREE)
	\|\| (walk_state->op_info->class == AML_CLASS_ARGUMENT)) {
	return_ACPI_STATUS(AE_OK);
	}

	/* Make sure that we only delete this subtree */

	if (op->common.parent) {
	prev = op->common.parent->common.value.arg;
	if (!prev) {

	/* Nothing more to do */

	goto cleanup;
	}

	/*
	* Check if we need to replace the operator and its subtree
	* with a return value op (placeholder op)
	*/
	parent_info =
	acpi_ps_get_opcode_info(op->common.parent->common.
	aml_opcode);

	switch (parent_info->class) {
	case AML_CLASS_CONTROL:
	break;

	case AML_CLASS_CREATE:

	/*
	* These opcodes contain term_arg operands. The current
	* op must be replaced by a placeholder return op
	*/
	replacement_op =
	acpi_ps_alloc_op(AML_INT_RETURN_VALUE_OP);
	if (!replacement_op) {
	status = AE_NO_MEMORY;
	}
	break;

	case AML_CLASS_NAMED_OBJECT:

	/*
	* These opcodes contain term_arg operands. The current
	* op must be replaced by a placeholder return op
	*/
	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_BUFFER_OP)
	\|\| (op->common.parent->common.aml_opcode ==
	AML_PACKAGE_OP)
	\|\| (op->common.parent->common.aml_opcode ==
	AML_BANK_FIELD_OP)
	\|\| (op->common.parent->common.aml_opcode ==
	AML_VAR_PACKAGE_OP)) {
	replacement_op =
	acpi_ps_alloc_op(AML_INT_RETURN_VALUE_OP);
	if (!replacement_op) {
	status = AE_NO_MEMORY;
	}
	} else
	if ((op->common.parent->common.aml_opcode ==
	AML_NAME_OP)
	&& (walk_state->pass_number <=
	ACPI_IMODE_LOAD_PASS2)) {
	if ((op->common.aml_opcode == AML_BUFFER_OP)
	\|\| (op->common.aml_opcode == AML_PACKAGE_OP)
	\|\| (op->common.aml_opcode ==
	AML_VAR_PACKAGE_OP)) {
	replacement_op =
	acpi_ps_alloc_op(op->common.
	aml_opcode);
	if (!replacement_op) {
	status = AE_NO_MEMORY;
	} else {
	replacement_op->named.data =
	op->named.data;
	replacement_op->named.length =
	op->named.length;
	}
	}
	}
	break;

	default:

	replacement_op =
	acpi_ps_alloc_op(AML_INT_RETURN_VALUE_OP);
	if (!replacement_op) {
	status = AE_NO_MEMORY;
	}
	}

	/* We must unlink this op from the parent tree */

	if (prev == op) {

	/* This op is the first in the list */

	if (replacement_op) {
	replacement_op->common.parent =
	op->common.parent;
	replacement_op->common.value.arg = NULL;
	replacement_op->common.node = op->common.node;
	op->common.parent->common.value.arg =
	replacement_op;
	replacement_op->common.next = op->common.next;
	} else {
	op->common.parent->common.value.arg =
	op->common.next;
	}
	}

	/* Search the parent list */

	else
	while (prev) {

	/* Traverse all siblings in the parent's argument list */

	next = prev->common.next;
	if (next == op) {
	if (replacement_op) {
	replacement_op->common.parent =
	op->common.parent;
	replacement_op->common.value.
	arg = NULL;
	replacement_op->common.node =
	op->common.node;
	prev->common.next =
	replacement_op;
	replacement_op->common.next =
	op->common.next;
	next = NULL;
	} else {
	prev->common.next =
	op->common.next;
	next = NULL;
	}
	}
	prev = next;
	}
	}

	cleanup:

	/* Now we can actually delete the subtree rooted at Op */

	acpi_ps_delete_parse_tree(op);
	return_ACPI_STATUS(status);
	}

	/*******************************************************************************
	*
	* FUNCTION: acpi_ps_next_parse_state
	*
	* PARAMETERS: walk_state - Current state
	* Op - Current parse op
	* callback_status - Status from previous operation
	*
	* RETURN: Status
	*
	* DESCRIPTION: Update the parser state based upon the return exception from
	* the parser callback.
	*
	******************************************************************************/

	acpi_status
	acpi_ps_next_parse_state(struct acpi_walk_state *walk_state,
	union acpi_parse_object *op,
	acpi_status callback_status)
	{
	struct acpi_parse_state *parser_state = &walk_state->parser_state;
	acpi_status status = AE_CTRL_PENDING;

	ACPI_FUNCTION_TRACE_PTR(ps_next_parse_state, op);

	switch (callback_status) {
	case AE_CTRL_TERMINATE:
	/*
	* A control method was terminated via a RETURN statement.
	* The walk of this method is complete.
	*/
	parser_state->aml = parser_state->aml_end;
	status = AE_CTRL_TERMINATE;
	break;

	case AE_CTRL_BREAK:

	parser_state->aml = walk_state->aml_last_while;
	walk_state->control_state->common.value = FALSE;
	status = AE_CTRL_BREAK;
	break;

	case AE_CTRL_CONTINUE:

	parser_state->aml = walk_state->aml_last_while;
	status = AE_CTRL_CONTINUE;
	break;

	case AE_CTRL_PENDING:

	parser_state->aml = walk_state->aml_last_while;
	break;

	#if 0
	case AE_CTRL_SKIP:

	parser_state->aml = parser_state->scope->parse_scope.pkg_end;
	status = AE_OK;
	break;
	#endif

	case AE_CTRL_TRUE:
	/*
	* Predicate of an IF was true, and we are at the matching ELSE.
	* Just close out this package
	*/
	parser_state->aml = acpi_ps_get_next_package_end(parser_state);
	status = AE_CTRL_PENDING;
	break;

	case AE_CTRL_FALSE:
	/*
	* Either an IF/WHILE Predicate was false or we encountered a BREAK
	* opcode. In both cases, we do not execute the rest of the
	* package; We simply close out the parent (finishing the walk of
	* this branch of the tree) and continue execution at the parent
	* level.
	*/
	parser_state->aml = parser_state->scope->parse_scope.pkg_end;

	/* In the case of a BREAK, just force a predicate (if any) to FALSE */

	walk_state->control_state->common.value = FALSE;
	status = AE_CTRL_END;
	break;

	case AE_CTRL_TRANSFER:

	/* A method call (invocation) -- transfer control */

	status = AE_CTRL_TRANSFER;
	walk_state->prev_op = op;
	walk_state->method_call_op = op;
	walk_state->method_call_node =
	(op->common.value.arg)->common.node;

	/* Will return value (if any) be used by the caller? */

	walk_state->return_used =
	acpi_ds_is_result_used(op, walk_state);
	break;

	default:

	status = callback_status;
	if ((callback_status & AE_CODE_MASK) == AE_CODE_CONTROL) {
	status = AE_OK;
	}
	break;
	}

	return_ACPI_STATUS(status);
	}

	/*******************************************************************************
	*
	* FUNCTION: acpi_ps_parse_aml
	*
	* PARAMETERS: walk_state - Current state
	*
	*
	* RETURN: Status
	*
	* DESCRIPTION: Parse raw AML and return a tree of ops
	*
	******************************************************************************/

	acpi_status acpi_ps_parse_aml(struct acpi_walk_state *walk_state)
	{
	acpi_status status;
	struct acpi_thread_state *thread;
	struct acpi_thread_state *prev_walk_list = acpi_gbl_current_walk_list;
	struct acpi_walk_state *previous_walk_state;

	ACPI_FUNCTION_TRACE(ps_parse_aml);

	ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
	"Entered with WalkState=%p Aml=%p size=%X\n",
	walk_state, walk_state->parser_state.aml,
	walk_state->parser_state.aml_size));

	if (!walk_state->parser_state.aml) {
	return_ACPI_STATUS(AE_NULL_OBJECT);
	}

	/* Create and initialize a new thread state */

	thread = acpi_ut_create_thread_state();
	if (!thread) {
	if (walk_state->method_desc) {

	/* Executing a control method - additional cleanup */

	acpi_ds_terminate_control_method(
	walk_state->method_desc, walk_state);
	}

	acpi_ds_delete_walk_state(walk_state);
	return_ACPI_STATUS(AE_NO_MEMORY);
	}

	walk_state->thread = thread;

	/*
	* If executing a method, the starting sync_level is this method's
	* sync_level
	*/
	if (walk_state->method_desc) {
	walk_state->thread->current_sync_level =
	walk_state->method_desc->method.sync_level;
	}

	acpi_ds_push_walk_state(walk_state, thread);

	/*
	* This global allows the AML debugger to get a handle to the currently
	* executing control method.
	*/
	acpi_gbl_current_walk_list = thread;

	/*
	* Execute the walk loop as long as there is a valid Walk State. This
	* handles nested control method invocations without recursion.
	*/
	ACPI_DEBUG_PRINT((ACPI_DB_PARSE, "State=%p\n", walk_state));

	status = AE_OK;
	while (walk_state) {
	if (ACPI_SUCCESS(status)) {
	/*
	* The parse_loop executes AML until the method terminates
	* or calls another method.
	*/
	status = acpi_ps_parse_loop(walk_state);
	}

	ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
	"Completed one call to walk loop, %s State=%p\n",
	acpi_format_exception(status), walk_state));

	if (status == AE_CTRL_TRANSFER) {
	/*
	* A method call was detected.
	* Transfer control to the called control method
	*/
	status =
	acpi_ds_call_control_method(thread, walk_state,
	NULL);
	if (ACPI_FAILURE(status)) {
	status =
	acpi_ds_method_error(status, walk_state);
	}

	/*
	* If the transfer to the new method method call worked, a new walk
	* state was created -- get it
	*/
	walk_state = acpi_ds_get_current_walk_state(thread);
	continue;
	} else if (status == AE_CTRL_TERMINATE) {
	status = AE_OK;
	} else if ((status != AE_OK) && (walk_state->method_desc)) {

	/* Either the method parse or actual execution failed */

	ACPI_ERROR_METHOD("Method parse/execution failed",
	walk_state->method_node, NULL,
	status);

	/* Check for possible multi-thread reentrancy problem */

	if ((status == AE_ALREADY_EXISTS) &&
	(!(walk_state->method_desc->method.
	info_flags & ACPI_METHOD_SERIALIZED))) {
	/*
	* Method is not serialized and tried to create an object
	* twice. The probable cause is that the method cannot
	* handle reentrancy. Mark as "pending serialized" now, and
	* then mark "serialized" when the last thread exits.
	*/
	walk_state->method_desc->method.info_flags \|=
	ACPI_METHOD_SERIALIZED_PENDING;
	}
	}

	/* We are done with this walk, move on to the parent if any */

	walk_state = acpi_ds_pop_walk_state(thread);

	/* Reset the current scope to the beginning of scope stack */

	acpi_ds_scope_stack_clear(walk_state);

	/*
	* If we just returned from the execution of a control method or if we
	* encountered an error during the method parse phase, there's lots of
	* cleanup to do
	*/
	if (((walk_state->parse_flags & ACPI_PARSE_MODE_MASK) ==
	ACPI_PARSE_EXECUTE) \|\| (ACPI_FAILURE(status))) {
	acpi_ds_terminate_control_method(walk_state->
	method_desc,
	walk_state);
	}

	/* Delete this walk state and all linked control states */

	acpi_ps_cleanup_scope(&walk_state->parser_state);
	previous_walk_state = walk_state;

	ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
	"ReturnValue=%p, ImplicitValue=%p State=%p\n",
	walk_state->return_desc,
	walk_state->implicit_return_obj, walk_state));

	/* Check if we have restarted a preempted walk */

	walk_state = acpi_ds_get_current_walk_state(thread);
	if (walk_state) {
	if (ACPI_SUCCESS(status)) {
	/*
	* There is another walk state, restart it.
	* If the method return value is not used by the parent,
	* The object is deleted
	*/
	if (!previous_walk_state->return_desc) {
	/*
	* In slack mode execution, if there is no return value
	* we should implicitly return zero (0) as a default value.
	*/
	if (acpi_gbl_enable_interpreter_slack &&
	!previous_walk_state->
	implicit_return_obj) {
	previous_walk_state->
	implicit_return_obj =
	acpi_ut_create_integer_object
	((u64) 0);
	if (!previous_walk_state->
	implicit_return_obj) {
	return_ACPI_STATUS
	(AE_NO_MEMORY);
	}
	}

	/* Restart the calling control method */

	status =
	acpi_ds_restart_control_method
	(walk_state,
	previous_walk_state->
	implicit_return_obj);
	} else {
	/*
	* We have a valid return value, delete any implicit
	* return value.
	*/
	acpi_ds_clear_implicit_return
	(previous_walk_state);

	status =
	acpi_ds_restart_control_method
	(walk_state,
	previous_walk_state->return_desc);
	}
	if (ACPI_SUCCESS(status)) {
	walk_state->walk_type \|=
	ACPI_WALK_METHOD_RESTART;
	}
	} else {
	/* On error, delete any return object or implicit return */

	acpi_ut_remove_reference(previous_walk_state->
	return_desc);
	acpi_ds_clear_implicit_return
	(previous_walk_state);
	}
	}

	/*
	* Just completed a 1st-level method, save the final internal return
	* value (if any)
	*/
	else if (previous_walk_state->caller_return_desc) {
	if (previous_walk_state->implicit_return_obj) {
	*(previous_walk_state->caller_return_desc) =
	previous_walk_state->implicit_return_obj;
	} else {
	/* NULL if no return value */

	*(previous_walk_state->caller_return_desc) =
	previous_walk_state->return_desc;
	}
	} else {
	if (previous_walk_state->return_desc) {

	/* Caller doesn't want it, must delete it */

	acpi_ut_remove_reference(previous_walk_state->
	return_desc);
	}
	if (previous_walk_state->implicit_return_obj) {

	/* Caller doesn't want it, must delete it */

	acpi_ut_remove_reference(previous_walk_state->
	implicit_return_obj);
	}
	}

	acpi_ds_delete_walk_state(previous_walk_state);
	}

	/* Normal exit */

	acpi_ex_release_all_mutexes(thread);
	acpi_ut_delete_generic_state(ACPI_CAST_PTR
	(union acpi_generic_state, thread));
	acpi_gbl_current_walk_list = prev_walk_list;
	return_ACPI_STATUS(status);
	}