5 files changed, 61 insertions, 20 deletions

diff --git a/drivers/acpi/acpica/acglobal.h b/drivers/acpi/acpica/acglobal.h
index 2b2e61ed373e..a419fe98a5fc 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_xpm1a_enable;
 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
diff --git a/drivers/acpi/acpica/actables.h b/drivers/acpi/acpica/actables.h
index 8ff3b741df28..fc52b6f2d69c 100644
--- a/drivers/acpi/acpica/actables.h
+++ b/drivers/acpi/acpica/actables.h
@@ -107,6 +107,8 @@ u8 acpi_tb_checksum(u8 *buffer, u32 length);
 acpi_status
 acpi_tb_verify_checksum(struct acpi_table_header *table, u32 length);
 
+void acpi_tb_check_dsdt_header(void);
+
 void
 acpi_tb_install_table(acpi_physical_address address,
                       char *signature, u32 table_index);
diff --git a/drivers/acpi/acpica/psxface.c b/drivers/acpi/acpica/psxface.c
index 6064dd4e94c2..67e7ad517051 100644
--- a/drivers/acpi/acpica/psxface.c
+++ b/drivers/acpi/acpica/psxface.c
@@ -220,6 +220,10 @@ acpi_status acpi_ps_execute_method(struct acpi_evaluate_info *info)
 
         ACPI_FUNCTION_TRACE(ps_execute_method);
 
+        /* Quick validation of DSDT header */
+
+        acpi_tb_check_dsdt_header();
+
         /* Validate the Info and method Node */
 
         if (!info || !info->resolved_node) {
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
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);