+/*******************************************************************************
+ *
+ * FUNCTION: acpi_tb_check_xsdt
+ *
+ * PARAMETERS: address - Pointer to the XSDT
+ *
+ * RETURN: status
+ * AE_OK - XSDT is okay
+ * AE_NO_MEMORY - can't map XSDT
+ * AE_INVALID_TABLE_LENGTH - invalid table length
+ * AE_NULL_ENTRY - XSDT has NULL entry
+ *
+ * DESCRIPTION: validate XSDT
+******************************************************************************/
+
+static acpi_status
+acpi_tb_check_xsdt(acpi_physical_address address)
+{
+ struct acpi_table_header *table;
+ u32 length;
+ u64 xsdt_entry_address;
+ u8 *table_entry;
+ u32 table_count;
+ int i;
+
+ table = acpi_os_map_memory(address, sizeof(struct acpi_table_header));
+ if (!table)
+ return AE_NO_MEMORY;
+
+ length = table->length;
+ acpi_os_unmap_memory(table, sizeof(struct acpi_table_header));
+ if (length < sizeof(struct acpi_table_header))
+ return AE_INVALID_TABLE_LENGTH;
+
+ table = acpi_os_map_memory(address, length);
+ if (!table)
+ return AE_NO_MEMORY;
+
+ /* Calculate the number of tables described in XSDT */
+ table_count =
+ (u32) ((table->length -
+ sizeof(struct acpi_table_header)) / sizeof(u64));
+ table_entry =
+ ACPI_CAST_PTR(u8, table) + sizeof(struct acpi_table_header);
+ for (i = 0; i < table_count; i++) {
+ ACPI_MOVE_64_TO_64(&xsdt_entry_address, table_entry);
+ if (!xsdt_entry_address) {
+ /* XSDT has NULL entry */
+ break;
+ }
+ table_entry += sizeof(u64);
+ }
+ acpi_os_unmap_memory(table, length);
+
+ if (i < table_count)
+ return AE_NULL_ENTRY;
+ else
+ return AE_OK;
+}