International Business Machines Corporation
Page frame security

Abstract:

Memory management that includes allocating physical memory having an append-only permission associated therewith to requesting user space applications is described. If a page frame is append-only, then data written to the page frame cannot be overwritten. Rather, any new data written to an append-only page frame must be written beginning at the next available write location within the page frame. An MMU determines whether a write request is requesting an append-only page frame, in which case, the MMU reserves the append-only page frame for the write request and consults a corresponding entry in a page table append to determine whether an offset associated with the write request is larger than a stored value in the entry that indicates the next available write location in the page frame. If so, the write request is executed and the data is written to the page frame beginning at the next available write location.