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, 12 insertions, 20 deletions

diff --git a/drivers/acpi/acpica/tbxface.c b/drivers/acpi/acpica/tbxface.c
index 684614d0d327..30565100b94c 100644
--- a/drivers/acpi/acpica/tbxface.c
+++ b/drivers/acpi/acpica/tbxface.c
@@ -518,33 +518,25 @@ static acpi_status acpi_tb_load_namespace(void)
 
         (void)acpi_ut_acquire_mutex(ACPI_MTX_TABLES);
 
+        acpi_gbl_DSDT = &acpi_gbl_root_table_list.tables[ACPI_TABLE_INDEX_DSDT];
+
         /*
-         * Load the namespace. The DSDT is required, but any SSDT and PSDT tables
-         * are optional.
+         * Load the namespace. The DSDT is required, but any SSDT and
+         * PSDT tables are optional. Verify the DSDT.
          */
         if (!acpi_gbl_root_table_list.count ||
-            !ACPI_COMPARE_NAME(&
-                               (acpi_gbl_root_table_list.
-                                tables[ACPI_TABLE_INDEX_DSDT].signature),
-                               ACPI_SIG_DSDT)
-            ||
-            ACPI_FAILURE(acpi_tb_verify_table
-                         (&acpi_gbl_root_table_list.
-                          tables[ACPI_TABLE_INDEX_DSDT]))) {
+            !ACPI_COMPARE_NAME(&acpi_gbl_DSDT->signature, ACPI_SIG_DSDT) ||
+            ACPI_FAILURE(acpi_tb_verify_table(acpi_gbl_DSDT))) {
                 status = AE_NO_ACPI_TABLES;
                 goto unlock_and_exit;
         }
 
-        /* A valid DSDT is required */
-
-        status =
-            acpi_tb_verify_table(&acpi_gbl_root_table_list.
-                                 tables[ACPI_TABLE_INDEX_DSDT]);
-        if (ACPI_FAILURE(status)) {
-
-                status = AE_NO_ACPI_TABLES;
-                goto unlock_and_exit;
-        }
+        /*
+         * Save the original DSDT header for detection of table corruption
+         * and/or replacement of the DSDT from outside the OS.
+         */
+        ACPI_MEMCPY(&acpi_gbl_original_dsdt_header, acpi_gbl_DSDT->pointer,
+                    sizeof(struct acpi_table_header));
 
         (void)acpi_ut_release_mutex(ACPI_MTX_TABLES);