ACPICA: Methods now implicitly return 0 in slack mode

Implemented an enhancement to the interpreter "slack mode". In the
absence of an explicit return or an implicitly returned object from
the last executed opcode, a control method will now implicitly
return an integer of value 0 for Microsoft compatibility.

http://www.acpica.org/bugzilla/show_bug.cgi?id=392

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/drivers/acpi/parser/psparse.c b/drivers/acpi/parser/psparse.c
index a8995ca52ee7..a4c4020c40e9 100644
--- a/drivers/acpi/parser/psparse.c
+++ b/drivers/acpi/parser/psparse.c
@@ -594,6 +594,30 @@ acpi_status acpi_ps_parse_aml(struct acpi_walk_state *walk_state)
                                  * The object is deleted
                                  */
                                 if (!previous_walk_state->return_desc) {
+                                        /*
+                                         * In slack mode execution, if there is no return value
+                                         * we should implicitly return zero (0) as a default value.
+                                         */
+                                        if (acpi_gbl_enable_interpreter_slack &&
+                                            !previous_walk_state->
+                                            implicit_return_obj) {
+                                                previous_walk_state->
+                                                    implicit_return_obj =
+                                                    acpi_ut_create_internal_object
+                                                    (ACPI_TYPE_INTEGER);
+                                                if (!previous_walk_state->
+                                                    implicit_return_obj) {
+                                                        return_ACPI_STATUS
+                                                            (AE_NO_MEMORY);
+                                                }
+
+                                                previous_walk_state->
+                                                    implicit_return_obj->
+                                                    integer.value = 0;
+                                        }
+
+                                        /* Restart the calling control method */
+
                                         status =
                                             acpi_ds_restart_control_method
                                             (walk_state,