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>

1 files changed, 38 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/tbutils.c b/drivers/acpi/acpica/tbutils.c
index f47a70e20063..07bc7437f82b 100644
--- a/drivers/acpi/acpica/tbutils.c
+++ b/drivers/acpi/acpica/tbutils.c
@@ -349,6 +349,44 @@ u8 acpi_tb_checksum(u8 *buffer, u32 length)
 
 /*******************************************************************************
  *
+ * FUNCTION:    acpi_tb_check_dsdt_header
+ *
+ * PARAMETERS:  None
+ *
+ * RETURN:      None
+ *
+ * DESCRIPTION: Quick compare to check validity of the DSDT. This will detect
+ *              if the DSDT has been replaced from outside the OS and/or if
+ *              the DSDT header has been corrupted.
+ *
+ ******************************************************************************/
+
+void acpi_tb_check_dsdt_header(void)
+{
+
+        /* Compare original length and checksum to current values */
+
+        if (acpi_gbl_original_dsdt_header.length !=
+            acpi_gbl_DSDT->pointer->length
+            || acpi_gbl_original_dsdt_header.checksum !=
+            acpi_gbl_DSDT->pointer->checksum) {
+                ACPI_ERROR((AE_INFO,
+                            "The DSDT has been corrupted or replaced - old, new headers below"));
+                acpi_tb_print_table_header(0, &acpi_gbl_original_dsdt_header);
+                acpi_tb_print_table_header(acpi_gbl_DSDT->address,
+                                           acpi_gbl_DSDT->pointer);
+
+                /* Disable further error messages */
+
+                acpi_gbl_original_dsdt_header.length =
+                    acpi_gbl_DSDT->pointer->length;
+                acpi_gbl_original_dsdt_header.checksum =
+                    acpi_gbl_DSDT->pointer->checksum;
+        }
+}
+
+/*******************************************************************************
+ *
  * FUNCTION:    acpi_tb_install_table
  *
  * PARAMETERS:  Address                 - Physical address of DSDT or FACS