1. A system comprising: a register operable to store a first data value; an evaluation module to evaluate whether the first data value corresponds to a second data value; a processor to execute a set of instructions to be performed in a predetermined sequence, wherein executing the sequence of instructions causes operations to be performed, the operations comprising: processing an instruction in the set of instructions to determine whether the instruction is being executed according to the predetermined sequence; and sending the second data value to the evaluation module, the second data value being associated with the processed instruction and having a value that represents the processed instruction's place in the predetermined sequence; an update module to update the first data value in response to an update signal associated with the processor's execution of the instructions according to the predetermined sequence; and an output module to generate an output signal if the second value does not correspond to the first data value.