System software uses access protection to protect sensitive memory locations from improper access. System software can restrict memory accesses for both user-mode and privileged-mode software. Restrictions can be placed on reads, writes, and instruction fetches. Access protection is available when virtual protected mode is enabled.
Access control applies to instruction fetches, data loads, and data stores. The TLB entry for a virtual page specifies the type of access allowed to the page.
The TLB entry also specifies a zone-protection field in the zone-protection register that is used to override the access controls specified by the TLB entry.