Mid-Point Metadata Relocation for Memory Safety
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Solution Overview
Problem
Existing memory safety mechanisms, such as memory tagging technology, incur high overheads due to increased pointer sizes, poor locality, and redundant metadata storage, leading to significant memory waste and performance impacts, particularly in managing memory allocations for large datasets.
Innovation Solution
The proposed solution involves storing tag metadata at the mid-point of a memory allocation, using a power of two encoding to determine the mid-point, and encoding this metadata once per allocation, which reduces memory overhead and improves cache locality by allowing direct access to metadata without redundant storage or updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If memory tagging technology uses a repeating memory tag for every data block, then memory safety can be ensured, but memory overhead increases significantly
Solution Approach 1:
The patent merges the metadata storage with the data storage by placing the memory tag at the mid-point of the memory allocation rather than storing separate tags for each data block. This consolidation reduces the total memory overhead while maintaining safety functionality.
Solution Approach 2:
The patent segments the memory allocation into three parts: data before the mid-point, metadata at the mid-point, and data after the mid-point. This segmentation allows the memory tag to be centrally located and accessed efficiently without requiring redundant storage throughout the entire data structure.
2Reliability
If metadata is stored separately for each memory block, then memory safety can be maintained, but cache locality deteriorates
Solution Approach 1:
By merging the metadata storage location with the data storage location (placing the tag at the mid-point of the allocation), the patent improves cache locality. The metadata is now co-located with the data it describes, eliminating the need to access separate metadata structures and reducing cache line misses.
3Reliability
If redundant metadata storage is used, then memory safety can be ensured, but performance deteriorates due to multiple redundant memory accesses
Solution Approach 1:
The patent extracts the essential safety information (the memory tag) from the redundant metadata storage and consolidates it into a single location at the mid-point of the allocation. This extraction eliminates the need for multiple redundant memory accesses while preserving the safety checking functionality.
Data Source
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AI summary
Technologies disclosed herein provide one example of a system that includes processor circuitry to be communicatively coupled to a memory circuitry. The processor circuitry is to receive a memory access request corresponding to an application for access to an address range in a memory allocation of the memory circuitry and to locate a metadata region within the memory allocation. The processor circuitry is also to, in response to a determination that the address range includes at least a portion of the metadata region, obtain first metadata stored in the metadata region, use the first metadata to determine an alternate memory address in a relocation region, and read, at the alternate memory address, displaced data from the portion of the metadata region included in the address range of the memory allocation. The address range includes one or more bytes of an expected allocation region of the memory allocation.