psargs.c

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/******************************************************************************
 *
 * Module Name: psargs - Parse AML opcode arguments
 *
 *****************************************************************************/

/*
 * Copyright (C) 2000 - 2006, 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/acnamesp.h>
#include <acpi/acdispat.h>

#define _COMPONENT          ACPI_PARSER
ACPI_MODULE_NAME("psargs")

/* Local prototypes */
static u32
acpi_ps_get_next_package_length(struct acpi_parse_state *parser_state);

static union acpi_parse_object *acpi_ps_get_next_field(struct acpi_parse_state
						       *parser_state);

/*******************************************************************************
 *
 * FUNCTION:    acpi_ps_get_next_package_length
 *
 * PARAMETERS:  parser_state        - Current parser state object
 *
 * RETURN:      Decoded package length. On completion, the AML pointer points
 *              past the length byte or bytes.
 *
 * DESCRIPTION: Decode and return a package length field.
 *              Note: Largest package length is 28 bits, from ACPI specification
 *
 ******************************************************************************/

static u32
acpi_ps_get_next_package_length(struct acpi_parse_state *parser_state)
{
	u8 *aml = parser_state->aml;
	u32 package_length = 0;
	acpi_native_uint byte_count;
	u8 byte_zero_mask = 0x3F;	/* Default [0:5] */

	ACPI_FUNCTION_TRACE("ps_get_next_package_length");

	/*
	 * Byte 0 bits [6:7] contain the number of additional bytes
	 * used to encode the package length, either 0,1,2, or 3
	 */
	byte_count = (aml[0] >> 6);
	parser_state->aml += (byte_count + 1);

	/* Get bytes 3, 2, 1 as needed */

	while (byte_count) {
		/*
		 * Final bit positions for the package length bytes:
		 *      Byte3->[20:27]
		 *      Byte2->[12:19]
		 *      Byte1->[04:11]
		 *      Byte0->[00:03]
		 */
		package_length |= (aml[byte_count] << ((byte_count << 3) - 4));

		byte_zero_mask = 0x0F;	/* Use bits [0:3] of byte 0 */
		byte_count--;
	}

	/* Byte 0 is a special case, either bits [0:3] or [0:5] are used */

	package_length |= (aml[0] & byte_zero_mask);
	return_UINT32(package_length);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ps_get_next_package_end
 *
 * PARAMETERS:  parser_state        - Current parser state object
 *
 * RETURN:      Pointer to end-of-package +1
 *
 * DESCRIPTION: Get next package length and return a pointer past the end of
 *              the package.  Consumes the package length field
 *
 ******************************************************************************/

u8 *acpi_ps_get_next_package_end(struct acpi_parse_state *parser_state)
{
	u8 *start = parser_state->aml;
	u32 package_length;

	ACPI_FUNCTION_TRACE("ps_get_next_package_end");

	/* Function below updates parser_state->Aml */

	package_length = acpi_ps_get_next_package_length(parser_state);

	return_PTR(start + package_length);	/* end of package */
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ps_get_next_namestring
 *
 * PARAMETERS:  parser_state        - Current parser state object
 *
 * RETURN:      Pointer to the start of the name string (pointer points into
 *              the AML.
 *
 * DESCRIPTION: Get next raw namestring within the AML stream.  Handles all name
 *              prefix characters.  Set parser state to point past the string.
 *              (Name is consumed from the AML.)
 *
 ******************************************************************************/

char *acpi_ps_get_next_namestring(struct acpi_parse_state *parser_state)
{
	u8 *start = parser_state->aml;
	u8 *end = parser_state->aml;

	ACPI_FUNCTION_TRACE("ps_get_next_namestring");

	/* Point past any namestring prefix characters (backslash or carat) */

	while (acpi_ps_is_prefix_char(*end)) {
		end++;
	}

	/* Decode the path prefix character */

	switch (*end) {
	case 0:

		/* null_name */

		if (end == start) {
			start = NULL;
		}
		end++;
		break;

	case AML_DUAL_NAME_PREFIX:

		/* Two name segments */

		end += 1 + (2 * ACPI_NAME_SIZE);
		break;

	case AML_MULTI_NAME_PREFIX_OP:

		/* Multiple name segments, 4 chars each, count in next byte */

		end += 2 + (*(end + 1) * ACPI_NAME_SIZE);
		break;

	default:

		/* Single name segment */

		end += ACPI_NAME_SIZE;
		break;
	}

	parser_state->aml = end;
	return_PTR((char *)start);
}

/*******************************************************************************
 *
 * FUNCTION:    acpi_ps_get_next_namepath
 *
 * PARAMETERS:  parser_state        - Current parser state object
 *              Arg                 - Where the namepath will be stored
 *              arg_count           - If the namepath points to a control method
 *                                    the method's argument is returned here.
 *              possible_method_call - Whether the namepath can possibly be the
 *                                    start of a method call
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Get next name (if method call, return # of required args).
 *              Names are looked up in the internal namespace to determine
 *              if the name represents a control method.  If a method
 *              is found, the number of arguments to the method is returned.
 *              This information is critical for parsing to continue correctly.
 *
 ******************************************************************************/

acpi_status
acpi_ps_get_next_namepath(struct acpi_walk_state *walk_state,
			  struct acpi_parse_state *parser_state,
			  union acpi_parse_object *arg, u8 possible_method_call)
{
	char *path;
	union acpi_parse_object *name_op;
	acpi_status status;
	union acpi_operand_object *method_desc;
	struct acpi_namespace_node *node;
	union acpi_generic_state scope_info;

	ACPI_FUNCTION_TRACE("ps_get_next_namepath");

	path = acpi_ps_get_next_namestring(parser_state);
	acpi_ps_init_op(arg, AML_INT_NAMEPATH_OP);

	/* Null path case is allowed, just exit */

	if (!path) {
		arg->common.value.name = path;
		return_ACPI_STATUS(AE_OK);
	}

	/* Setup search scope info */

	scope_info.scope.node = NULL;
	node = parser_state->start_node;
	if (node) {
		scope_info.scope.node = node;
	}

	/*
	 * Lookup the name in the internal namespace. We don't want to add
	 * anything new to the namespace here, however, so we use MODE_EXECUTE.
	 * Allow searching of the parent tree, but don't open a new scope -
	 * we just want to lookup the object (must be mode EXECUTE to perform
	 * the upsearch)
	 */
	status =
	    acpi_ns_lookup(&scope_info, path, ACPI_TYPE_ANY, ACPI_IMODE_EXECUTE,
			   ACPI_NS_SEARCH_PARENT | ACPI_NS_DONT_OPEN_SCOPE,
			   NULL, &node);

	/*
	 * If this name is a control method invocation, we must
	 * setup the method call
	 */
	if (ACPI_SUCCESS(status) &&
	    possible_method_call && (node->type == ACPI_TYPE_METHOD)) {
		/* This name is actually a control method invocation */

		method_desc = acpi_ns_get_attached_object(node);
		ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
				  "Control Method - %p Desc %p Path=%p\n", node,
				  method_desc, path));

		name_op = acpi_ps_alloc_op(AML_INT_NAMEPATH_OP);
		if (!name_op) {
			return_ACPI_STATUS(AE_NO_MEMORY);
		}

		/* Change Arg into a METHOD CALL and attach name to it */

		acpi_ps_init_op(arg, AML_INT_METHODCALL_OP);
		name_op->common.value.name = path;

		/* Point METHODCALL/NAME to the METHOD Node */

		name_op->common.node = node;
		acpi_ps_append_arg(arg, name_op);

		if (!method_desc) {
			ACPI_ERROR((AE_INFO,
				    "Control Method %p has no attached object",
				    node));
			return_ACPI_STATUS(AE_AML_INTERNAL);
		}

		ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
				  "Control Method - %p Args %X\n",
				  node, method_desc->method.param_count));

		/* Get the number of arguments to expect */

		walk_state->arg_count = method_desc->method.param_count;
		return_ACPI_STATUS(AE_OK);
	}

	/*
	 * Special handling if the name was not found during the lookup -
	 * some not_found cases are allowed
	 */
	if (status == AE_NOT_FOUND) {
		/* 1) not_found is ok during load pass 1/2 (allow forward references) */

		if ((walk_state->parse_flags & ACPI_PARSE_MODE_MASK) !=
		    ACPI_PARSE_EXECUTE) {
			status = AE_OK;
		}

		/* 2) not_found during a cond_ref_of(x) is ok by definition */

		else if (walk_state->op->common.aml_opcode ==
			 AML_COND_REF_OF_OP) {
			status = AE_OK;
		}

		/*
		 * 3) not_found while building a Package is ok at this point, we
		 * may flag as an error later if slack mode is not enabled.
		 * (Some ASL code depends on allowing this behavior)
		 */
		else if ((arg->common.parent) &&
			 ((arg->common.parent->common.aml_opcode ==
			   AML_PACKAGE_OP)
			  || (arg->common.parent->common.aml_opcode ==
			      AML_VAR_PACKAGE_OP))) {
			status = AE_OK;
		}
	}

	/* Final exception check (may have been changed from code above) */

	if (ACPI_FAILURE(status)) {
		ACPI_ERROR_NAMESPACE(path, status);

		if ((walk_state->parse_flags & ACPI_PARSE_MODE_MASK) ==
		    ACPI_PARSE_EXECUTE) {
			/* Report a control method execution error */

			status = acpi_ds_method_error(status, walk_state);
		}
	}