ACPICA: Add detection of corrupted/replaced DSDT

This change adds support to detect a DSDT that has been corrupted
and/or replaced from outside the OS (by firmware). This is
typically catastrophic for the system, but has been seen on
some machines.

https://bugzilla.kernel.org/show_bug.cgi?id=14679

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/acpica/acglobal.h b/drivers/acpi/acpica/acglobal.h
index 2b2e61e..a419fe9 100644
--- a/drivers/acpi/acpica/acglobal.h
+++ b/drivers/acpi/acpica/acglobal.h
@@ -165,6 +165,11 @@
 ACPI_EXTERN struct acpi_generic_address acpi_gbl_xpm1b_status;
 ACPI_EXTERN struct acpi_generic_address acpi_gbl_xpm1b_enable;
 
+/* DSDT information. Used to check for DSDT corruption */
+
+ACPI_EXTERN struct acpi_table_desc *acpi_gbl_DSDT;
+ACPI_EXTERN struct acpi_table_header acpi_gbl_original_dsdt_header;
+
 /*
  * Handle both ACPI 1.0 and ACPI 2.0 Integer widths. The integer width is
  * determined by the revision of the DSDT: If the DSDT revision is less than