STORING SECURE MODE PAGE TABLE DATA IN SECURE AND NON-SECURE REGIONS OF MEMORY

摘要

The data processing apparatus 2 includes a processing circuit 8 operating in one or more security modes 40 and one or more unsecured modes 42. [ When operating in unsecured mode, one or more areas of memory are inaccessible. The memory management unit 24 manages access to the memory including the secure memory 22 and the non-secure memory 6 in response to the page table data. Security mode page table data 36, 38 is used when operating in one of the security modes. The page table entry in the layer of the page table of the secure mode page table data includes a table security field (not shown) indicating whether the additional page table indicated by the corresponding page table entry is stored in the secure memory 22 or in the non- 68, and 72, respectively. If any of the page tables associated with memory accesses are stored in the non-secure memory 6, the memory accesses are marked with a table attribute bit NST indicating that the memory accesses should be handled non-securely.