PERMISSION CONTROL FOR CONTINGENT MEMORY ACCESS PROGRAM INSTRUCTION

A DATA PROCESSING APPARATUS AND METHOD SERVE TO MANAGE ACCESS PERMISSION CHECKING IN RESPECT OF CONTINGENT MEMORY ACCESS OPERATIONS (THE ACCESS PERMISSION FAILURE OF WHICH DOES NOT ALTER PROGRAM FLOW) IN DEPENDENCE OF A CONTINGENT-ACCESS PERMISSION CHECKING DISABLE FLAG. IF THE CONTINGENT ACCESS DISABLE FLAG HAS A FIRST VALUE, THEN THIS DISABLES MEMORY PERMISSION CIRCUITRY E.G. A WALK STATE MACHINE 22, FROM PERFORMING A CHECK AS TO WHETHER OR NOT THE MEMORY ACCESS CIRCUITRY IS PERMITTED TO PERFORM A REQUESTED MEMORY ACCESS. NON-CONTINGENT MEMORY ACCESSES ARE ABLE TO UTILISE THE MEMORY PERMISSION CIRCUITRY IRRESPECTIVE OF THE VALUE OF THE CONTINGENT-ACCESS PERMISSION CHECKING DISABLE FLAG. (FIGURE 9)