MetaTableLite: An Efficient Metadata Management Scheme for Tagged-Pointer-Based Spatial Safety

Abstract

A tagged-pointer-based memory spatial safety protection system utilizes the unused bits in a pointer to store the boundary information of an object. This paper proposed a hybrid metadata management scheme, MetaTableLite, for tagged-pointer-based protections. We observed that objects of a large size only take a minority part of all the objects in a program. However, recording their boundary metadata with traditional pointer tags will incur large memory overheads. Based on this observation, we introduce a small supplementary table to maintain metadata for these few large objects. For small ones, MetaTableLite represents their boundaries with a 14-bit pointer tag, well utilizing the unused 16 bits in a conventional 64-bit pointer. MetaTableLite can achieve a 6% average memory overhead without alternating the conventional pointer representation.