Integrated circuit with restricted data access

摘要

A semiconductor integrated circuit includes a hardware mechanism arranged to ensure that associations between instructions and data are enforced so that a processor cannot fetch data from an instruction that is not authorised to do so. A Memory Protection Unit stores entries comprising instructions and associated data memory ranges. A hardware arrangement impairs the operation of the circuit if the CPU attempts to make a data fetch from an instruction that is outside the range associated with data in a Memory Protection Unit. Such functioning may be by issuing a chip reset. The Memory Protection Unit may be implemented in a Memory Management Unit having an extension so as to store a validity flag. The validity flag may only be set by a secure process such as the CPU well entrusted code or by a separate trusted hardware source. In this way, an operating system may function as normal referring to the Memory Management Unit as necessary, but security may be enforced through hardware.