ACPICA 20050708 from Bob Moore <robert.moore@intel.com>

The use of the CPU stack in the debug version of the
subsystem has been considerably reduced.  Previously, a
debug structure was declared in every function that used
the debug macros.  This structure has been removed in
favor of declaring the individual elements as parameters
to the debug functions.  This reduces the cumulative stack
use during nested execution of ACPI function calls at the
cost of a small increase in the code size of the debug
version of the subsystem.  With assistance from Alexey
Starikovskiy and Len Brown.

Added the ACPI_GET_FUNCTION_NAME macro to enable the
compiler-dependent headers to define a macro that will
return the current function name at runtime (such as
__FUNCTION__ or _func_, etc.) The function name is used
by the debug trace output.  If ACPI_GET_FUNCTION_NAME
is not defined in the compiler-dependent header, the
function name is saved on the CPU stack (one pointer per
function.) This mechanism is used because apparently there
exists no standard ANSI-C defined macro that that returns
the function name.

Alexey Starikovskiy redesigned and reimplemented the
"Owner ID" mechanism used to track namespace objects
created/deleted by ACPI tables and control method
execution.  A bitmap is now used to allocate and free the
IDs, thus solving the wraparound problem present in the
previous implementation.  The size of the namespace node
descriptor was reduced by 2 bytes as a result.

Removed the UINT32_BIT and UINT16_BIT types that were used
for the bitfield flag definitions within the headers for
the predefined ACPI tables.  These have been replaced by
UINT8_BIT in order to increase the code portability of
the subsystem.  If the use of UINT8 remains a problem,
we may be forced to eliminate bitfields entirely because
of a lack of portability.

Alexey Starikovksiy enhanced the performance of
acpi_ut_update_object_reference.  This is a frequently used
function and this improvement increases the performance
of the entire subsystem.

Alexey Starikovskiy fixed several possible memory leaks
and the inverse - premature object deletion.

Signed-off-by: Len Brown <len.brown@intel.com>

39 files changed, 664 insertions, 540 deletions

diff --git a/drivers/acpi/dispatcher/dsinit.c b/drivers/acpi/dispatcher/dsinit.c
index d7790db50178..ebc07aab710c 100644
--- a/drivers/acpi/dispatcher/dsinit.c
+++ b/drivers/acpi/dispatcher/dsinit.c
@@ -99,7 +99,7 @@ acpi_ds_init_one_object (
 	 * was just loaded
 	 */
 	if (((struct acpi_namespace_node *) obj_handle)->owner_id !=
-			info->table_desc->table_id) {
+			info->table_desc->owner_id) {
 		return (AE_OK);
 	}
 
@@ -168,7 +168,7 @@ acpi_ds_init_one_object (
 		 */
 		acpi_ns_delete_namespace_subtree (obj_handle);
 		acpi_ns_delete_namespace_by_owner (
-			((struct acpi_namespace_node *) obj_handle)->object->method.owning_id);
+			((struct acpi_namespace_node *) obj_handle)->object->method.owner_id);
 		break;
 
 
@@ -237,7 +237,7 @@ acpi_ds_initialize_objects (
 
 	ACPI_DEBUG_PRINT_RAW ((ACPI_DB_INIT,
 		"\nTable [%4.4s](id %4.4X) - %hd Objects with %hd Devices %hd Methods %hd Regions\n",
-		table_desc->pointer->signature, table_desc->table_id, info.object_count,
+		table_desc->pointer->signature, table_desc->owner_id, info.object_count,
 		info.device_count, info.method_count, info.op_region_count));
 
 	ACPI_DEBUG_PRINT ((ACPI_DB_DISPATCH,
diff --git a/drivers/acpi/dispatcher/dsmethod.c b/drivers/acpi/dispatcher/dsmethod.c
index c9d9a6c45ae3..1b90813cbde1 100644
--- a/drivers/acpi/dispatcher/dsmethod.c
+++ b/drivers/acpi/dispatcher/dsmethod.c
@@ -77,7 +77,6 @@ acpi_ds_parse_method (
 	union acpi_operand_object       *obj_desc;
 	union acpi_parse_object         *op;
 	struct acpi_namespace_node      *node;
-	acpi_owner_id                   owner_id;
 	struct acpi_walk_state          *walk_state;
 
 
@@ -132,15 +131,18 @@ acpi_ds_parse_method (
 	 * objects (such as Operation Regions) can be created during the
 	 * first pass parse.
 	 */
-	owner_id = acpi_ut_allocate_owner_id (ACPI_OWNER_TYPE_METHOD);
-	obj_desc->method.owning_id = owner_id;
+	status = acpi_ut_allocate_owner_id (&obj_desc->method.owner_id);
+	if (ACPI_FAILURE (status)) {
+		goto cleanup;
+	}
 
 	/* Create and initialize a new walk state */
 
-	walk_state = acpi_ds_create_walk_state (owner_id, NULL, NULL, NULL);
+	walk_state = acpi_ds_create_walk_state (
+			  obj_desc->method.owner_id, NULL, NULL, NULL);
 	if (!walk_state) {
 		status = AE_NO_MEMORY;
-		goto cleanup;
+		goto cleanup2;
 	}
 
 	status = acpi_ds_init_aml_walk (walk_state, op, node,
@@ -148,7 +150,7 @@ acpi_ds_parse_method (
 			  obj_desc->method.aml_length, NULL, 1);
 	if (ACPI_FAILURE (status)) {
 		acpi_ds_delete_walk_state (walk_state);
-		goto cleanup;
+		goto cleanup2;
 	}
 
 	/*
@@ -162,13 +164,16 @@ acpi_ds_parse_method (
 	 */
 	status = acpi_ps_parse_aml (walk_state);
 	if (ACPI_FAILURE (status)) {
-		goto cleanup;
+		goto cleanup2;
 	}
 
 	ACPI_DEBUG_PRINT ((ACPI_DB_PARSE,
 		"**** [%4.4s] Parsed **** named_obj=%p Op=%p\n",
 		acpi_ut_get_node_name (obj_handle), obj_handle, op));
 
+cleanup2:
+	(void) acpi_ut_release_owner_id (obj_desc->method.owner_id);
+
 cleanup:
 	acpi_ps_delete_parse_tree (op);
 	return_ACPI_STATUS (status);
@@ -265,7 +270,7 @@ acpi_ds_call_control_method (
 {
 	acpi_status                     status;
 	struct acpi_namespace_node      *method_node;
-	struct acpi_walk_state          *next_walk_state;
+	struct acpi_walk_state          *next_walk_state = NULL;
 	union acpi_operand_object       *obj_desc;
 	struct acpi_parameter_info      info;
 	u32                             i;
@@ -289,20 +294,23 @@ acpi_ds_call_control_method (
 		return_ACPI_STATUS (AE_NULL_OBJECT);
 	}
 
-	obj_desc->method.owning_id = acpi_ut_allocate_owner_id (ACPI_OWNER_TYPE_METHOD);
+	status = acpi_ut_allocate_owner_id (&obj_desc->method.owner_id);
+	if (ACPI_FAILURE (status)) {
+		return_ACPI_STATUS (status);
+	}
 
 	/* Init for new method, wait on concurrency semaphore */
 
 	status = acpi_ds_begin_method_execution (method_node, obj_desc,
 			  this_walk_state->method_node);
 	if (ACPI_FAILURE (status)) {
-		return_ACPI_STATUS (status);
+		goto cleanup;
 	}
 
 	if (!(obj_desc->method.method_flags & AML_METHOD_INTERNAL_ONLY)) {
 		/* 1) Parse: Create a new walk state for the preempting walk */
 
-		next_walk_state = acpi_ds_create_walk_state (obj_desc->method.owning_id,
+		next_walk_state = acpi_ds_create_walk_state (obj_desc->method.owner_id,
 				  op, obj_desc, NULL);
 		if (!next_walk_state) {
 			return_ACPI_STATUS (AE_NO_MEMORY);
@@ -332,7 +340,7 @@ acpi_ds_call_control_method (
 
 	/* 2) Execute: Create a new state for the preempting walk */
 
-	next_walk_state = acpi_ds_create_walk_state (obj_desc->method.owning_id,
+	next_walk_state = acpi_ds_create_walk_state (obj_desc->method.owner_id,
 			  NULL, obj_desc, thread);
 	if (!next_walk_state) {
 		status = AE_NO_MEMORY;
@@ -383,6 +391,7 @@ acpi_ds_call_control_method (
 	/* On error, we must delete the new walk state */
 
 cleanup:
+	(void) acpi_ut_release_owner_id (obj_desc->method.owner_id);
 	if (next_walk_state && (next_walk_state->method_desc)) {
 		/* Decrement the thread count on the method parse tree */
 
@@ -584,7 +593,7 @@ acpi_ds_terminate_control_method (
 		 * Delete any namespace entries created anywhere else within
 		 * the namespace
 		 */
-		acpi_ns_delete_namespace_by_owner (walk_state->method_desc->method.owning_id);
+		acpi_ns_delete_namespace_by_owner (walk_state->method_desc->method.owner_id);
 		status = acpi_ut_release_mutex (ACPI_MTX_NAMESPACE);
 		if (ACPI_FAILURE (status)) {
 			return_ACPI_STATUS (status);
diff --git a/drivers/acpi/executer/exconfig.c b/drivers/acpi/executer/exconfig.c
index 8bfa6effaa0c..76c6ebd0231f 100644
--- a/drivers/acpi/executer/exconfig.c
+++ b/drivers/acpi/executer/exconfig.c
@@ -487,7 +487,7 @@ acpi_ex_unload_table (
 	 * Delete the entire namespace under this table Node
 	 * (Offset contains the table_id)
 	 */
-	acpi_ns_delete_namespace_by_owner (table_info->table_id);
+	acpi_ns_delete_namespace_by_owner (table_info->owner_id);
 
 	/* Delete the table itself */
 
diff --git a/drivers/acpi/executer/exdump.c b/drivers/acpi/executer/exdump.c
index 7007abb6051e..6158f5193f4a 100644
--- a/drivers/acpi/executer/exdump.c
+++ b/drivers/acpi/executer/exdump.c
@@ -819,7 +819,7 @@ acpi_ex_dump_object_descriptor (
 		acpi_ex_out_integer ("param_count", obj_desc->method.param_count);
 		acpi_ex_out_integer ("Concurrency", obj_desc->method.concurrency);
 		acpi_ex_out_pointer ("Semaphore",   obj_desc->method.semaphore);
-		acpi_ex_out_integer ("owning_id",   obj_desc->method.owning_id);
+		acpi_ex_out_integer ("owner_id",    obj_desc->method.owner_id);
 		acpi_ex_out_integer ("aml_length",  obj_desc->method.aml_length);
 		acpi_ex_out_pointer ("aml_start",   obj_desc->method.aml_start);
 		break;
diff --git a/drivers/acpi/executer/exoparg1.c b/drivers/acpi/executer/exoparg1.c
index 131f49acb1df..c1ba8b48228e 100644
--- a/drivers/acpi/executer/exoparg1.c
+++ b/drivers/acpi/executer/exoparg1.c
@@ -904,6 +904,7 @@ acpi_ex_opcode_1A_0T_1R (
 			 */
 			return_desc = acpi_ns_get_attached_object (
 					  (struct acpi_namespace_node *) operand[0]);
+			acpi_ut_add_reference (return_desc);
 		}
 		else {
 			/*
@@ -953,20 +954,10 @@ acpi_ex_opcode_1A_0T_1R (
 					 * add another reference to the referenced object, however.
 					 */
 					return_desc = *(operand[0]->reference.where);
-					if (!return_desc) {
-						/*
-						 * We can't return a NULL dereferenced value.  This is
-						 * an uninitialized package element and is thus a
-						 * severe error.
-						 */
-						ACPI_DEBUG_PRINT ((ACPI_DB_ERROR,
-							"NULL package element obj %p\n",
-							operand[0]));
-						status = AE_AML_UNINITIALIZED_ELEMENT;
-						goto cleanup;
+					if (return_desc) {
+	                    acpi_ut_add_reference (return_desc);
 					}
 
-					acpi_ut_add_reference (return_desc);
 					break;
 
 
diff --git a/drivers/acpi/executer/exresop.c b/drivers/acpi/executer/exresop.c
index d8b470eefe7a..aaba7abcb52d 100644
--- a/drivers/acpi/executer/exresop.c
+++ b/drivers/acpi/executer/exresop.c
@@ -426,6 +426,10 @@ acpi_ex_resolve_operands (
 
 				return_ACPI_STATUS (status);
 			}
+
+			if (obj_desc != *stack_ptr) {
+				acpi_ut_remove_reference (obj_desc);
+			}
 			goto next_operand;
 
 
@@ -448,6 +452,10 @@ acpi_ex_resolve_operands (
 
 				return_ACPI_STATUS (status);
 			}
+
+			if (obj_desc != *stack_ptr) {
+				acpi_ut_remove_reference (obj_desc);
+			}
 			goto next_operand;
 
 
@@ -471,6 +479,10 @@ acpi_ex_resolve_operands (
 
 				return_ACPI_STATUS (status);
 			}
+
+			if (obj_desc != *stack_ptr) {
+				acpi_ut_remove_reference (obj_desc);
+			}
 			goto next_operand;
 
 
@@ -515,6 +527,10 @@ acpi_ex_resolve_operands (
 				if (ACPI_FAILURE (status)) {
 					return_ACPI_STATUS (status);
 				}
+
+				if (obj_desc != *stack_ptr) {
+					acpi_ut_remove_reference (obj_desc);
+				}
 				break;
 
 			default:
diff --git a/drivers/acpi/namespace/nsaccess.c b/drivers/acpi/namespace/nsaccess.c
index 9df0a64ba9e9..0bda88d18685 100644
--- a/drivers/acpi/namespace/nsaccess.c
+++ b/drivers/acpi/namespace/nsaccess.c
@@ -163,7 +163,7 @@ acpi_ns_root_initialize (
 
 				/*
 				 * i_aSL Compiler cheats by putting parameter count
-				 * in the owner_iD
+				 * in the owner_iD (param_count max is 7)
 				 */
 				new_node->owner_id = obj_desc->method.param_count;
 #else
diff --git a/drivers/acpi/namespace/nsalloc.c b/drivers/acpi/namespace/nsalloc.c
index 3f94b0806ecf..edbf1db36b68 100644
--- a/drivers/acpi/namespace/nsalloc.c
+++ b/drivers/acpi/namespace/nsalloc.c
@@ -190,7 +190,7 @@ acpi_ns_install_node (
 	struct acpi_namespace_node      *node,          /* New Child*/
 	acpi_object_type                type)
 {
-	u16                             owner_id = 0;
+	acpi_owner_id                   owner_id = 0;
 	struct acpi_namespace_node      *child_node;
 #ifdef ACPI_ALPHABETIC_NAMESPACE
 
@@ -559,7 +559,7 @@ acpi_ns_remove_reference (
 
 void
 acpi_ns_delete_namespace_by_owner (
-	u16                             owner_id)
+	acpi_owner_id                    owner_id)
 {
 	struct acpi_namespace_node      *child_node;
 	struct acpi_namespace_node      *deletion_node;
@@ -635,6 +635,7 @@ acpi_ns_delete_namespace_by_owner (
 		}
 	}
 
+	(void) acpi_ut_release_owner_id (owner_id);
 	return_VOID;
 }
 
diff --git a/drivers/acpi/namespace/nsdump.c b/drivers/acpi/namespace/nsdump.c
index c9f35dd7a431..d86ccbc8a134 100644
--- a/drivers/acpi/namespace/nsdump.c
+++ b/drivers/acpi/namespace/nsdump.c
@@ -203,7 +203,7 @@ acpi_ns_dump_one_object (
 
 	/* Check if the owner matches */
 
-	if ((info->owner_id != ACPI_UINT32_MAX) &&
+	if ((info->owner_id != ACPI_OWNER_ID_MAX) &&
 		(info->owner_id != this_node->owner_id)) {
 		return (AE_OK);
 	}
@@ -598,7 +598,7 @@ acpi_ns_dump_objects (
 	acpi_object_type                type,
 	u8                              display_type,
 	u32                             max_depth,
-	u32                             owner_id,
+	acpi_owner_id                   owner_id,
 	acpi_handle                     start_handle)
 {
 	struct acpi_walk_info           info;
@@ -643,7 +643,7 @@ acpi_ns_dump_entry (
 
 
 	info.debug_level = debug_level;
-	info.owner_id = ACPI_UINT32_MAX;
+	info.owner_id = ACPI_OWNER_ID_MAX;
 	info.display_type = ACPI_DISPLAY_SUMMARY;
 
 	(void) acpi_ns_dump_one_object (handle, 1, &info, NULL);
@@ -694,7 +694,7 @@ acpi_ns_dump_tables (
 	}
 
 	acpi_ns_dump_objects (ACPI_TYPE_ANY, ACPI_DISPLAY_OBJECTS, max_depth,
-			ACPI_UINT32_MAX, search_handle);
+			ACPI_OWNER_ID_MAX, search_handle);
 	return_VOID;
 }
 #endif	/* _ACPI_ASL_COMPILER */
diff --git a/drivers/acpi/namespace/nsparse.c b/drivers/acpi/namespace/nsparse.c
index f81b836e77f1..64e0b2b9f55c 100644
--- a/drivers/acpi/namespace/nsparse.c
+++ b/drivers/acpi/namespace/nsparse.c
@@ -87,7 +87,7 @@ acpi_ns_one_complete_parse (
 
 	/* Create and initialize a new walk state */
 
-	walk_state = acpi_ds_create_walk_state (table_desc->table_id,
+	walk_state = acpi_ds_create_walk_state (table_desc->owner_id,
 			   NULL, NULL, NULL);
 	if (!walk_state) {
 		acpi_ps_free_op (parse_root);
diff --git a/drivers/acpi/parser/psloop.c b/drivers/acpi/parser/psloop.c
index decb2e9a049d..095672a1a722 100644
--- a/drivers/acpi/parser/psloop.c
+++ b/drivers/acpi/parser/psloop.c
@@ -407,9 +407,14 @@ acpi_ps_parse_loop (
 					INCREMENT_ARG_LIST (walk_state->arg_types);
 				}
 
+
 				/* Special processing for certain opcodes */
 
-				if ((walk_state->pass_number <= ACPI_IMODE_LOAD_PASS1) &&
+	/* TBD (remove): Temporary mechanism to disable this code if needed */
+
+#ifndef ACPI_NO_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
@@ -434,7 +439,7 @@ acpi_ps_parse_loop (
 						break;
 					}
 				}
-
+#endif
 				switch (op->common.aml_opcode) {
 				case AML_METHOD_OP:
 
diff --git a/drivers/acpi/parser/psxface.c b/drivers/acpi/parser/psxface.c
index dba893648e84..5279b51e7787 100644
--- a/drivers/acpi/parser/psxface.c
+++ b/drivers/acpi/parser/psxface.c
@@ -138,11 +138,14 @@ acpi_psx_execute (
 	 * objects (such as Operation Regions) can be created during the
 	 * first pass parse.
 	 */
-	obj_desc->method.owning_id = acpi_ut_allocate_owner_id (ACPI_OWNER_TYPE_METHOD);
+	status = acpi_ut_allocate_owner_id (&obj_desc->method.owner_id);
+	if (ACPI_FAILURE (status)) {
+		goto cleanup2;
+	}
 
 	/* Create and initialize a new walk state */
 
-	walk_state = acpi_ds_create_walk_state (obj_desc->method.owning_id,
+	walk_state = acpi_ds_create_walk_state (obj_desc->method.owner_id,
 			   NULL, NULL, NULL);
 	if (!walk_state) {
 		status = AE_NO_MEMORY;
diff --git a/drivers/acpi/tables/tbinstal.c b/drivers/acpi/tables/tbinstal.c
index 629b64c8193d..2ad72f204551 100644
--- a/drivers/acpi/tables/tbinstal.c
+++ b/drivers/acpi/tables/tbinstal.c
@@ -251,6 +251,7 @@ acpi_tb_init_table_descriptor (
 {
 	struct acpi_table_list          *list_head;
 	struct acpi_table_desc          *table_desc;
+	acpi_status                     status;
 
 
 	ACPI_FUNCTION_TRACE_U32 ("tb_init_table_descriptor", table_type);
@@ -263,6 +264,13 @@ acpi_tb_init_table_descriptor (
 		return_ACPI_STATUS (AE_NO_MEMORY);
 	}
 
+	/* Get a new owner ID for the table */
+
+	status = acpi_ut_allocate_owner_id (&table_desc->owner_id);
+	if (ACPI_FAILURE (status)) {
+		return_ACPI_STATUS (status);
+	}
+
 	/* Install the table into the global data structure */
 
 	list_head = &acpi_gbl_table_lists[table_type];
@@ -325,8 +333,6 @@ acpi_tb_init_table_descriptor (
 	table_desc->aml_start           = (u8 *) (table_desc->pointer + 1),
 	table_desc->aml_length          = (u32) (table_desc->length -
 			 (u32) sizeof (struct acpi_table_header));
-	table_desc->table_id            = acpi_ut_allocate_owner_id (
-			 ACPI_OWNER_TYPE_TABLE);
 	table_desc->loaded_into_namespace = FALSE;
 
 	/*
@@ -339,7 +345,7 @@ acpi_tb_init_table_descriptor (
 
 	/* Return Data */
 
-	table_info->table_id        = table_desc->table_id;
+	table_info->owner_id        = table_desc->owner_id;
 	table_info->installed_desc  = table_desc;
 
 	return_ACPI_STATUS (AE_OK);
diff --git a/drivers/acpi/tables/tbrsdt.c b/drivers/acpi/tables/tbrsdt.c
index 13c6ddb2f546..069d498465d0 100644
--- a/drivers/acpi/tables/tbrsdt.c
+++ b/drivers/acpi/tables/tbrsdt.c
@@ -96,32 +96,13 @@ acpi_tb_verify_rsdp (
 		return_ACPI_STATUS (AE_BAD_PARAMETER);
 	}
 
-	/*
-	 *  The signature and checksum must both be correct
-	 */
-	if (ACPI_STRNCMP ((char *) rsdp, RSDP_SIG, sizeof (RSDP_SIG)-1) != 0) {
-		/* Nope, BAD Signature */
-
-		status = AE_BAD_SIGNATURE;
-		goto cleanup;
-	}
-
-	/* Check the standard checksum */
+	/* Verify RSDP signature and checksum */
 
-	if (acpi_tb_checksum (rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
-		status = AE_BAD_CHECKSUM;
+	status = acpi_tb_validate_rsdp (rsdp);
+	if (ACPI_FAILURE (status)) {
 		goto cleanup;
 	}
 
-	/* Check extended checksum if table version >= 2 */
-
-	if (rsdp->revision >= 2) {
-		if (acpi_tb_checksum (rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0) {
-			status = AE_BAD_CHECKSUM;
-			goto cleanup;
-		}
-	}
-
 	/* The RSDP supplied is OK */
 
 	table_info.pointer     = ACPI_CAST_PTR (struct acpi_table_header, rsdp);
diff --git a/drivers/acpi/tables/tbxface.c b/drivers/acpi/tables/tbxface.c
index 0c0b9085dbeb..ca2dbdd23ed3 100644
--- a/drivers/acpi/tables/tbxface.c
+++ b/drivers/acpi/tables/tbxface.c
@@ -260,8 +260,7 @@ acpi_unload_table (
 		 * "Scope" operator.  Thus, we need to track ownership by an ID, not
 		 * simply a position within the hierarchy
 		 */
-		acpi_ns_delete_namespace_by_owner (table_desc->table_id);
-
+		acpi_ns_delete_namespace_by_owner (table_desc->owner_id);
 		table_desc = table_desc->next;
 	}
 
diff --git a/drivers/acpi/tables/tbxfroot.c b/drivers/acpi/tables/tbxfroot.c
index fe9c8317df46..abb4c9346560 100644
--- a/drivers/acpi/tables/tbxfroot.c
+++ b/drivers/acpi/tables/tbxfroot.c
@@ -65,6 +65,51 @@ acpi_tb_scan_memory_for_rsdp (
 
 /*******************************************************************************
  *
+ * FUNCTION:    acpi_tb_validate_rsdp
+ *
+ * PARAMETERS:  Rsdp        - Pointer to unvalidated RSDP
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Validate the RSDP (ptr)
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_tb_validate_rsdp (
+	struct rsdp_descriptor          *rsdp)
+{
+	ACPI_FUNCTION_ENTRY ();
+
+
+	/*
+	 *  The signature and checksum must both be correct
+	 */
+	if (ACPI_STRNCMP ((char *) rsdp, RSDP_SIG, sizeof (RSDP_SIG)-1) != 0) {
+		/* Nope, BAD Signature */
+
+		return (AE_BAD_SIGNATURE);
+	}
+
+	/* Check the standard checksum */
+
+	if (acpi_tb_checksum (rsdp, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
+		return (AE_BAD_CHECKSUM);
+	}
+
+	/* Check extended checksum if table version >= 2 */
+
+	if ((rsdp->revision >= 2) &&
+		(acpi_tb_checksum (rsdp, ACPI_RSDP_XCHECKSUM_LENGTH) != 0)) {
+		return (AE_BAD_CHECKSUM);
+	}
+
+	return (AE_OK);
+}
+
+
+/*******************************************************************************
+ *
  * FUNCTION:    acpi_tb_find_table
  *
  * PARAMETERS:  Signature           - String with ACPI table signature
@@ -218,19 +263,11 @@ acpi_get_firmware_table (
 			acpi_gbl_RSDP = address.pointer.logical;
 		}
 
-		/* The signature and checksum must both be correct */
-
-		if (ACPI_STRNCMP ((char *) acpi_gbl_RSDP, RSDP_SIG,
-				sizeof (RSDP_SIG)-1) != 0) {
-			/* Nope, BAD Signature */
+		/* The RDSP signature and checksum must both be correct */
 
-			return_ACPI_STATUS (AE_BAD_SIGNATURE);
-		}
-
-		if (acpi_tb_checksum (acpi_gbl_RSDP, ACPI_RSDP_CHECKSUM_LENGTH) != 0) {
-			/* Nope, BAD Checksum */
-
-			return_ACPI_STATUS (AE_BAD_CHECKSUM);
+		status = acpi_tb_validate_rsdp (acpi_gbl_RSDP);
+		if (ACPI_FAILURE (status)) {
+			return_ACPI_STATUS (status);
 		}
 	}
 
@@ -414,9 +451,9 @@ acpi_tb_scan_memory_for_rsdp (
 	u8                              *start_address,
 	u32                             length)
 {
+	acpi_status                     status;
 	u8                              *mem_rover;
 	u8                              *end_address;
-	u8                              checksum;
 
 
 	ACPI_FUNCTION_TRACE ("tb_scan_memory_for_rsdp");
@@ -428,45 +465,25 @@ acpi_tb_scan_memory_for_rsdp (
 
 	for (mem_rover = start_address; mem_rover < end_address;
 		 mem_rover += ACPI_RSDP_SCAN_STEP) {
-		/* The signature and checksum must both be correct */
+		/* The RSDP signature and checksum must both be correct */
 
-		if (ACPI_STRNCMP ((char *) mem_rover,
-				RSDP_SIG, sizeof (RSDP_SIG) - 1) != 0) {
-			/* No signature match, keep looking */
-
-			continue;
-		}
-
-		/* Signature matches, check the appropriate checksum */
-
-		if ((ACPI_CAST_PTR (struct rsdp_descriptor, mem_rover))->revision < 2) {
-			/* ACPI version 1.0 */
-
-			checksum = acpi_tb_checksum (mem_rover, ACPI_RSDP_CHECKSUM_LENGTH);
-		}
-		else {
-			/* Post ACPI 1.0, use extended_checksum */
-
-			checksum = acpi_tb_checksum (mem_rover, ACPI_RSDP_XCHECKSUM_LENGTH);
-		}
-
-		if (checksum == 0) {
-			/* Checksum valid, we have found a valid RSDP */
+		status = acpi_tb_validate_rsdp (ACPI_CAST_PTR (struct rsdp_descriptor, mem_rover));
+		if (ACPI_SUCCESS (status)) {
+			/* Sig and checksum valid, we have found a real RSDP */
 
 			ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
 				"RSDP located at physical address %p\n", mem_rover));
 			return_PTR (mem_rover);
 		}
 
-		ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
-			"Found an RSDP at physical address %p, but it has a bad checksum\n",
-			mem_rover));
+		/* No sig match or bad checksum, keep searching */
 	}
 
 	/* Searched entire block, no RSDP was found */
 
 	ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
-		"Searched entire block, no valid RSDP was found.\n"));
+		"Searched entire block from %p, valid RSDP was not found\n",
+		start_address));
 	return_PTR (NULL);
 }
 
@@ -554,7 +571,7 @@ acpi_tb_find_rsdp (
 			acpi_os_unmap_memory (table_ptr, ACPI_EBDA_WINDOW_SIZE);
 
 			if (mem_rover) {
-				/* Found it, return the physical address */
+				/* Return the physical address */
 
 				physical_address += ACPI_PTR_DIFF (mem_rover, table_ptr);