ACPI_DEBUG_PRINT((ACPI_DB_DISPATCH, "[WHILE_OP] Op=%p\n", op));
- if (walk_state->control_state->common.value) {
+ control_state = walk_state->control_state;
+ if (control_state->common.value) {
- /* Predicate was true, go back and evaluate it again! */
+ /* Predicate was true, the body of the loop was just executed */
+ /*
+ * This loop counter mechanism allows the interpreter to escape
+ * possibly infinite loops. This can occur in poorly written AML
+ * when the hardware does not respond within a while loop and the
+ * loop does not implement a timeout.
+ */
+ control_state->control.loop_count++;
+ if (control_state->control.loop_count >
+ ACPI_MAX_LOOP_ITERATIONS) {
+ status = AE_AML_INFINITE_LOOP;
+ break;
+ }
+
+ /*
+ * Go back and evaluate the predicate and maybe execute the loop
+ * another time
+ */
status = AE_CTRL_PENDING;
walk_state->aml_last_while =
- walk_state->control_state->control.aml_predicate_start;
+ control_state->control.aml_predicate_start;
break;
}
#define ACPI_ROOT_TABLE_SIZE_INCREMENT 4
+/* Maximum number of While() loop iterations before forced abort */
+
+#define ACPI_MAX_LOOP_ITERATIONS 0xFFFF
+
/******************************************************************************
*
* ACPI Specification constants (Do not change unless the specification changes)
#define AE_AML_CIRCULAR_REFERENCE (acpi_status) (0x001E | AE_CODE_AML)
#define AE_AML_BAD_RESOURCE_LENGTH (acpi_status) (0x001F | AE_CODE_AML)
#define AE_AML_ILLEGAL_ADDRESS (acpi_status) (0x0020 | AE_CODE_AML)
+#define AE_AML_INFINITE_LOOP (acpi_status) (0x0021 | AE_CODE_AML)
-#define AE_CODE_AML_MAX 0x0020
+#define AE_CODE_AML_MAX 0x0021
/*
* Internal exceptions used for control
"AE_AML_CIRCULAR_REFERENCE",
"AE_AML_BAD_RESOURCE_LENGTH",
"AE_AML_ILLEGAL_ADDRESS",
+ "AE_AML_INFINITE_LOOP"
};
char const *acpi_gbl_exception_names_ctrl[] = {
union acpi_parse_object *predicate_op;
u8 *aml_predicate_start; /* Start of if/while predicate */
u8 *package_end; /* End of if/while block */
+ u32 loop_count; /* While() loop counter */
};
/*