psloop.c

/******************************************************************************
 *
 * Module Name: psloop - Main AML parse loop
 *
 *****************************************************************************/

/*
 * 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.
 */

/*
 * 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 <acpi/acparser.h>
#include <acpi/acdispat.h>
#include <acpi/amlcode.h>

#define _COMPONENT          ACPI_PARSER
ACPI_MODULE_NAME("psloop")

static u32 acpi_gbl_depth = 0;

/*******************************************************************************
 *
 * FUNCTION:    acpi_ps_parse_loop
 *
 * PARAMETERS:  walk_state          - Current state
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Parse AML (pointed to by the current parser state) and return
 *              a tree of ops.
 *
 ******************************************************************************/

acpi_status acpi_ps_parse_loop(struct acpi_walk_state *walk_state)
{
	acpi_status status = AE_OK;
	acpi_status status2;
	union acpi_parse_object *op = NULL;	/* current op */
	union acpi_parse_object *arg = NULL;
	union acpi_parse_object *pre_op = NULL;
	struct acpi_parse_state *parser_state;
	u8 *aml_op_start = NULL;

	ACPI_FUNCTION_TRACE_PTR("ps_parse_loop", walk_state);

	if (walk_state->descending_callback == NULL) {
		return_ACPI_STATUS(AE_BAD_PARAMETER);
	}

	parser_state = &walk_state->parser_state;
	walk_state->arg_types = 0;

#if (!defined (ACPI_NO_METHOD_EXECUTION) && !defined (ACPI_CONSTANT_EVAL_ONLY))

	if (walk_state->walk_type & ACPI_WALK_METHOD_RESTART) {
		/* We are restarting a preempted control method */

		if (acpi_ps_has_completed_scope(parser_state)) {
			/*
			 * We must check if a predicate to an IF or WHILE statement
			 * was just completed
			 */
			if ((parser_state->scope->parse_scope.op) &&
			    ((parser_state->scope->parse_scope.op->common.
			      aml_opcode == AML_IF_OP)
			     || (parser_state->scope->parse_scope.op->common.
				 aml_opcode == AML_WHILE_OP))
			    && (walk_state->control_state)
			    && (walk_state->control_state->common.state ==
				ACPI_CONTROL_PREDICATE_EXECUTING)) {
				/*
				 * A predicate was just completed, get the value of the
				 * predicate and branch based on that value
				 */
				walk_state->op = NULL;
				status =
				    acpi_ds_get_predicate_value(walk_state,
								ACPI_TO_POINTER
								(TRUE));
				if (ACPI_FAILURE(status)
				    && ((status & AE_CODE_MASK) !=
					AE_CODE_CONTROL)) {
					if (status == AE_AML_NO_RETURN_VALUE) {
						ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
								  "Invoked method did not return a value, %s\n",
								  acpi_format_exception
								  (status)));

					}
					ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
							  "get_predicate Failed, %s\n",
							  acpi_format_exception
							  (status)));
					return_ACPI_STATUS(status);
				}

				status =
				    acpi_ps_next_parse_state(walk_state, op,
							     status);
			}

			acpi_ps_pop_scope(parser_state, &op,
					  &walk_state->arg_types,
					  &walk_state->arg_count);
			ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
					  "Popped scope, Op=%p\n", op));
		} else if (walk_state->prev_op) {
			/* We were in the middle of an op */

			op = walk_state->prev_op;
			walk_state->arg_types = walk_state->prev_arg_types;
		}
	}
#endif

	/* Iterative parsing loop, while there is more AML to process: */

	while ((parser_state->aml < parser_state->aml_end) || (op)) {
		aml_op_start = parser_state->aml;
		if (!op) {
			/* Get the next opcode from the AML stream */

			walk_state->aml_offset =
			    (u32) ACPI_PTR_DIFF(parser_state->aml,
						parser_state->aml_start);
			walk_state->opcode = acpi_ps_peek_opcode(parser_state);

			/*
			 * First cut to determine what we have found:
			 * 1) A valid AML opcode
			 * 2) A name string
			 * 3) An unknown/invalid opcode
			 */
			walk_state->op_info =
			    acpi_ps_get_opcode_info(walk_state->opcode);
			switch (walk_state->op_info->class) {
			case AML_CLASS_ASCII:
			case AML_CLASS_PREFIX:
				/*
				 * Starts with a valid prefix or ASCII char, this is a name
				 * string.  Convert the bare name string to a namepath.
				 */
				walk_state->opcode = AML_INT_NAMEPATH_OP;
				walk_state->arg_types = ARGP_NAMESTRING;
				break;

			case AML_CLASS_UNKNOWN:

				/* The opcode is unrecognized.  Just skip unknown opcodes */

				ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
						  "Found unknown opcode %X at AML address %p offset %X, ignoring\n",
						  walk_state->opcode,
						  parser_state->aml,
						  walk_state->aml_offset));

				ACPI_DUMP_BUFFER(parser_state->aml, 128);

				/* Assume one-byte bad opcode */

				parser_state->aml++;
				continue;

			default:

				/* Found opcode info, this is a normal opcode */

				parser_state->aml +=
				    acpi_ps_get_opcode_size(walk_state->opcode);
				walk_state->arg_types =
				    walk_state->op_info->parse_args;
				break;
			}

			/* Create Op structure and append to parent's argument list */

			if (walk_state->op_info->flags & AML_NAMED) {
				/* Allocate a new pre_op if necessary */

				if (!pre_op) {
					pre_op =
					    acpi_ps_alloc_op(walk_state->
							     opcode);
					if (!pre_op) {
						status = AE_NO_MEMORY;
						goto close_this_op;
					}
				}

				pre_op->common.value.arg = NULL;
				pre_op->common.aml_opcode = walk_state->opcode;

				/*
				 * Get and append arguments until we find the node that contains
				 * the name (the type ARGP_NAME).
				 */
				while (GET_CURRENT_ARG_TYPE
				       (walk_state->arg_types)
				       &&
				       (GET_CURRENT_ARG_TYPE
					(walk_state->arg_types) != ARGP_NAME)) {
					status =
					    acpi_ps_get_next_arg(walk_state,
								 parser_state,
								 GET_CURRENT_ARG_TYPE
								 (walk_state->
								  arg_types),
								 &arg);
					if (ACPI_FAILURE(status)) {
						goto close_this_op;
					}

					acpi_ps_append_arg(pre_op, arg);
					INCREMENT_ARG_LIST(walk_state->
							   arg_types);
				}

				/*
				 * Make sure that we found a NAME and didn't run out of
				 * arguments
				 */
				if (!GET_CURRENT_ARG_TYPE
				    (walk_state->arg_types)) {
					status = AE_AML_NO_OPERAND;
					goto close_this_op;
				}

				/* We know that this arg is a name, move to next arg */

				INCREMENT_ARG_LIST(walk_state->arg_types);

				/*
				 * Find the object.  This will either insert the object into
				 * the namespace or simply look it up
				 */
				walk_state->op = NULL;

				status =
				    walk_state->descending_callback(walk_state,
								    &op);
				if (ACPI_FAILURE(status)) {
					ACPI_DEBUG_PRINT((ACPI_DB_ERROR,
							  "During name lookup/catalog, %s\n",
							  acpi_format_exception
							  (status)));
					goto close_this_op;
				}

				if (!op) {
					continue;
				}

				status =
				    acpi_ps_next_parse_state(walk_state, op,
							     status);
				if (status == AE_CTRL_PENDING) {
					status = AE_OK;
					goto close_this_op;
				}

				if (ACPI_FAILURE(status)) {
					goto close_this_op;
				}

				acpi_ps_append_arg(op,
						   pre_op->common.value.arg);
				acpi_gbl_depth++;

				if (op->common.aml_opcode == AML_REGION_OP) {
					/*
					 * Defer final parsing of an operation_region body,
					 * because we don't have enough info in the first pass
					 * to parse it correctly (i.e., there may be method
					 * calls within the term_arg elements of the body.)
					 *
					 * However, we must continue parsing because
					 * the opregion is not a standalone package --
					 * we don't know where the end is at this point.
					 *
					 * (Length is unknown until parse of the body complete)
					 */
					op->named.data = aml_op_start;
					op->named.length = 0;
				}
			} else {
				/* Not a named opcode, just allocate Op and append to parent */

				walk_state->op_info =
				    acpi_ps_get_opcode_info(walk_state->opcode);
				op = acpi_ps_alloc_op(walk_state->opcode);
				if (!op) {
					status = AE_NO_MEMORY;
					goto close_this_op;
				}

				if (walk_state->op_info->flags & AML_CREATE) {
					/*
					 * Backup to beginning of create_xXXfield declaration
					 * body_length is unknown until we parse the body
					 */
					op->named.data = aml_op_start;
					op->named.length = 0;
				}

				acpi_ps_append_arg(acpi_ps_get_parent_scope
						   (parser_state), op);

				if ((walk_state->descending_callback != NULL)) {
					/*
					 * Find the object. This will either insert the object into
					 * the namespace or simply look it up
					 */
					walk_state->op = op;

					status =
					    walk_state->
					    descending_callback(walk_state,
								&op);
					status =
					    acpi_ps_next_parse_state(walk_state,
								     op,
								     status);
					if (status == AE_CTRL_PENDING) {
						status = AE_OK;
						goto close_this_op;
					}

					if (ACPI_FAILURE(status)) {
						goto close_this_op;
					}
				}
			}

			op->common.aml_offset = walk_state->aml_offset;

			if (walk_state->op_info) {
				ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
						  "Opcode %4.4X [%s] Op %p Aml %p aml_offset %5.5X\n",
						  (u32) op->common.aml_opcode,
						  walk_state->op_info->name, op,
						  parser_state->aml,
						  op->common.aml_offset));
			}
		}

		/*
		 * Start arg_count at zero because we don't know if there are
		 * any args yet
		 */
		walk_state->arg_count = 0;

		/* Are there any arguments that must be processed? */

		if (walk_state->arg_types) {
			/* Get arguments */

			switch (op->common.aml_opcode) {
			case AML_BYTE_OP:	/* AML_BYTEDATA_ARG */
			case AML_WORD_OP:	/* AML_WORDDATA_ARG */
			case AML_DWORD_OP:	/* AML_DWORDATA_ARG */
			case AML_QWORD_OP:	/* AML_QWORDATA_ARG */
			case AML_STRING_OP:	/* AML_ASCIICHARLIST_ARG */

				/* Fill in constant or string argument directly */

				acpi_ps_get_next_simple_arg(parser_state,
							    GET_CURRENT_ARG_TYPE
							    (walk_state->
							     arg_types), op);
				break;

			case AML_INT_NAMEPATH_OP:	/* AML_NAMESTRING_ARG */

				status =
				    acpi_ps_get_next_namepath(walk_state,
							      parser_state, op,
							      1);
				if (ACPI_FAILURE(status)) {
					goto close_this_op;
				}

				walk_state->arg_types = 0;
				break;

			default:
				/*
				 * Op is not a constant or string, append each argument
				 * to the Op
				 */
				while (GET_CURRENT_ARG_TYPE
				       (walk_state->arg_types)
				       && !walk_state->arg_count) {
					walk_state->aml_offset = (u32)
					    ACPI_PTR_DIFF(parser_state->aml,
							  parser_state->
							  aml_start);

					status =
					    acpi_ps_get_next_arg(walk_state,
								 parser_state,
								 GET_CURRENT_ARG_TYPE
								 (walk_state->
								  arg_types),
								 &arg);
					if (ACPI_FAILURE(status)) {
						goto close_this_op;
					}

					if (arg) {
						arg->common.aml_offset =
						    walk_state->aml_offset;
						acpi_ps_append_arg(op, arg);
					}
					INCREMENT_ARG_LIST(walk_state->
							   arg_types);
				}

				/* Special processing for certain opcodes */

				/* TBD (remove): Temporary mechanism to disable this code if needed */

#ifdef ACPI_ENABLE_MODULE_LEVEL_CODE

				if ((walk_state->pass_number <=
				     ACPI_IMODE_LOAD_PASS1)
				    &&
				    ((walk_state->
				      parse_flags & ACPI_PARSE_DISASSEMBLE) ==
				     0)) {
					/*
					 * We want to skip If/Else/While constructs during Pass1
					 * because we want to actually conditionally execute the
					 * code during Pass2.
					 *
					 * Except for disassembly, where we always want to
					 * walk the If/Else/While packages
					 */
					switch (op->common.aml_opcode) {
					case AML_IF_OP:
					case AML_ELSE_OP:
					case AML_WHILE_OP:

						ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
								  "Pass1: Skipping an If/Else/While body\n"));

						/* Skip body of if/else/while in pass 1 */

						parser_state->aml =
						    parser_state->pkg_end;
						walk_state->arg_count = 0;
						break;

					default:
						break;
					}
				}
#endif
				switch (op->common.aml_opcode) {
				case AML_METHOD_OP:

					/*
					 * Skip parsing of control method
					 * because we don't have enough info in the first pass
					 * to parse it correctly.
					 *
					 * Save the length and address of the body
					 */
					op->named.data = parser_state->aml;
					op->named.length =
					    (u32) (parser_state->pkg_end -
						   parser_state->aml);

					/* Skip body of method */

					parser_state->aml =
					    parser_state->pkg_end;
					walk_state->arg_count = 0;
					break;

				case AML_BUFFER_OP:
				case AML_PACKAGE_OP:
				case AML_VAR_PACKAGE_OP:

					if ((op->common.parent) &&
					    (op->common.parent->common.
					     aml_opcode == AML_NAME_OP)
					    && (walk_state->pass_number <=
						ACPI_IMODE_LOAD_PASS2)) {
						/*
						 * Skip parsing of Buffers and Packages
						 * because we don't have enough info in the first pass
						 * to parse them correctly.
						 */
						op->named.data = aml_op_start;
						op->named.length =
						    (u32) (parser_state->
							   pkg_end -
							   aml_op_start);

						/* Skip body */

						parser_state->aml =
						    parser_state->pkg_end;
						walk_state->arg_count = 0;
					}
					break;

				case AML_WHILE_OP:

					if (walk_state->control_state) {
						walk_state->control_state->
						    control.package_end =
						    parser_state->pkg_end;
					}
					break;

				default:

					/* No action for all other opcodes */
					break;
				}
				break;
			}
		}

		/* Check for arguments that need to be processed */

		if (walk_state->arg_count) {
			/*
			 * There are arguments (complex ones), push Op and
			 * prepare for argument
			 */
			status = acpi_ps_push_scope(parser_state, op,
						    walk_state->arg_types,
						    walk_state->arg_count);
			if (ACPI_FAILURE(status)) {
				goto close_this_op;
			}
			op = NULL;
			continue;
		}

		/*
		 * All arguments have been processed -- Op is complete,
		 * prepare for next
		 */
		walk_state->op_info =
		    acpi_ps_get_opcode_info(op->common.aml_opcode);
		if (walk_state->op_info->flags & AML_NAMED) {
			if (acpi_gbl_depth) {
				acpi_gbl_depth--;
			}

			if (op->common.aml_opcode == AML_REGION_OP) {
				/*
				 * Skip parsing of control method or opregion body,
				 * because we don't have enough info in the first pass
				 * to parse them correctly.
				 *
				 * Completed parsing an op_region declaration, we now
				 * know the length.
				 */
				op->named.length =
				    (u32) (parser_state->aml - op->named.data);
			}
		}

		if (walk_state->op_info->flags & AML_CREATE) {
			/*
			 * Backup to beginning of create_xXXfield declaration (1 for
			 * Opcode)
			 *
			 * body_length is unknown until we parse the body
			 */
			op->named.length =
			    (u32) (parser_state->aml - op->named.data);
		}

		/* This op complete, notify the dispatcher */

		if (walk_state->ascending_callback != NULL) {
			walk_state->op = op;
			walk_state->opcode = op->common.aml_opcode;

			status = walk_state->ascending_callback(walk_state);
			status =
			    acpi_ps_next_parse_state(walk_state, op, status);
			if (status == AE_CTRL_PENDING) {
				status = AE_OK;
				goto close_this_op;
			}
		}

	      close_this_op:
		/*
		 * Finished one argument of the containing scope
		 */
		parser_state->scope->parse_scope.arg_count--;

		/* Finished with pre_op */

		if (pre_op) {
			acpi_ps_free_op(pre_op);
			pre_op = NULL;
		}

		/* Close this Op (will result in parse subtree deletion) */

		status2 = acpi_ps_complete_this_op(walk_state, op);
		if (ACPI_FAILURE(status2)) {
			return_ACPI_STATUS(status2);
		}
		op = NULL;

		switch (status) {
		case AE_OK:
			break;

		case AE_CTRL_TRANSFER:

			/* We are about to transfer to a called method. */

			walk_state->prev_op = op;
			walk_state->prev_arg_types = walk_state->arg_types;
			return_ACPI_STATUS(status);

		case AE_CTRL_END:

			acpi_ps_pop_scope(parser_state, &op,
					  &walk_state->arg_types,
					  &walk_state->arg_count);

			if (op) {
				walk_state->op = op;
				walk_state->op_info =
				    acpi_ps_get_opcode_info(op->common.
							    aml_opcode);
				walk_state->opcode = op->common.aml_opcode;

				status =
				    walk_state->ascending_callback(walk_state);
				status =
				    acpi_ps_next_parse_state(walk_state, op,
							     status);

				status2 =
				    acpi_ps_complete_this_op(walk_state, op);
				if (ACPI_FAILURE(status2)) {
					return_ACPI_STATUS(status2);
				}
				op = NULL;
			}
			status = AE_OK;
			break;

		case AE_CTRL_BREAK:
		case AE_CTRL_CONTINUE:

			/* Pop off scopes until we find the While */

			while (!op || (op->common.aml_opcode != AML_WHILE_OP)) {
				acpi_ps_pop_scope(parser_state, &op,
						  &walk_state->arg_types,
						  &walk_state->arg_count);
			}

			/* Close this iteration of the While loop */

			walk_state->op = op;
			walk_state->op_info =
			    acpi_ps_get_opcode_info(op->common.aml_opcode);
			walk_state->opcode = op->common.aml_opcode;

			status = walk_state->ascending_callback(walk_state);
			status =
			    acpi_ps_next_parse_state(walk_state, op, status);

			status2 = acpi_ps_complete_this_op(walk_state, op);
			if (ACPI_FAILURE(status2)) {
				return_ACPI_STATUS(status2);
			}
			op = NULL;

			status = AE_OK;
			break;

		case AE_CTRL_TERMINATE:

			status = AE_OK;

			/* Clean up */
			do {
				if (op) {
					status2 =
					    acpi_ps_complete_this_op(walk_state,
								     op);
					if (ACPI_FAILURE(status2)) {
						return_ACPI_STATUS(status2);
					}
				}
				acpi_ps_pop_scope(parser_state, &op,
						  &walk_state->arg_types,
						  &walk_state->arg_count);

			} while (op);

			return_ACPI_STATUS(status);

		default:	/* All other non-AE_OK status */

			do {
				if (op) {
					status2 =
					    acpi_ps_complete_this_op(walk_state,
								     op);
					if (ACPI_FAILURE(status2)) {
						return_ACPI_STATUS(status2);
					}
				}
				acpi_ps_pop_scope(parser_state, &op,
						  &walk_state->arg_types,
						  &walk_state->arg_count);

			} while (op);

			/*
			 * TBD: Cleanup parse ops on error
			 */
#if 0
			if (op == NULL) {
				acpi_ps_pop_scope(parser_state, &op,
						  &walk_state->arg_types,
						  &walk_state->arg_count);
			}
#endif
			walk_state->prev_op = op;
			walk_state->prev_arg_types = walk_state->arg_types;
			return_ACPI_STATUS(status);
		}

		/* This scope complete? */

		if (acpi_ps_has_completed_scope(parser_state)) {
			acpi_ps_pop_scope(parser_state, &op,
					  &walk_state->arg_types,
					  &walk_state->arg_count);
			ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
					  "Popped scope, Op=%p\n", op));
		} else {
			op = NULL;
		}

	}			/* while parser_state->Aml */

	/*
	 * Complete the last Op (if not completed), and clear the scope stack.
	 * It is easily possible to end an AML "package" with an unbounded number
	 * of open scopes (such as when several ASL blocks are closed with
	 * sequential closing braces).  We want to terminate each one cleanly.
	 */
	ACPI_DEBUG_PRINT((ACPI_DB_PARSE, "AML package complete at Op %p\n",
			  op));
	do {
		if (op) {
			if (walk_state->ascending_callback != NULL) {
				walk_state->op = op;
				walk_state->op_info =
				    acpi_ps_get_opcode_info(op->common.
							    aml_opcode);
				walk_state->opcode = op->common.aml_opcode;

				status =
				    walk_state->ascending_callback(walk_state);
				status =
				    acpi_ps_next_parse_state(walk_state, op,
							     status);
				if (status == AE_CTRL_PENDING) {
					status = AE_OK;
					goto close_this_op;
				}

				if (status == AE_CTRL_TERMINATE) {
					status = AE_OK;

					/* Clean up */
					do {
						if (op) {
							status2 =
							    acpi_ps_complete_this_op
							    (walk_state, op);
							if (ACPI_FAILURE
							    (status2)) {
								return_ACPI_STATUS
								    (status2);
							}
						}

						acpi_ps_pop_scope(parser_state,
								  &op,
								  &walk_state->
								  arg_types,
								  &walk_state->
								  arg_count);

					} while (op);

					return_ACPI_STATUS(status);
				}

				else if (ACPI_FAILURE(status)) {
					/* First error is most important */

					(void)
					    acpi_ps_complete_this_op(walk_state,
								     op);
					return_ACPI_STATUS(status);
				}
			}

			status2 = acpi_ps_complete_this_op(walk_state, op);
			if (ACPI_FAILURE(status2)) {
				return_ACPI_STATUS(status2);
			}
		}

		acpi_ps_pop_scope(parser_state, &op, &walk_state->arg_types,
				  &walk_state->arg_count);

	} while (op);

	return_ACPI_STATUS(status);
}