Hardware Pointer Revocation Pipeline for Temporal Memory Safety
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Solution Overview
Problem
Existing methods for improving temporal memory safety in computing systems often result in significant performance loss and memory usage, making them impractical for applications requiring low latency, such as vehicle safety systems.
Innovation Solution
A hardware revocation engine with a pipeline architecture that shares memory access with the main processor, allowing for efficient and low-latency scanning and invalidation of pointers to deallocated memory, utilizing a shadow memory system to track memory deallocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If software-based pointer revocation methods are used to ensure temporal memory safety, then memory safety is improved, but performance loss increases and memory usage increases
Solution Approach 1:
The patent replaces software-based pointer revocation mechanisms with a hardware-based revocation engine that operates in parallel with the main processor. This hardware engine includes a revocation pipeline with multiple stages that can scan and invalidate pointers to deallocated memory without blocking the main processor, thereby maintaining memory safety while minimizing performance impact.
Solution Approach 2:
The revocation pipeline is divided into multiple stages (first stage, second stage, etc.) that operate in parallel cycles. Each stage performs specific functions such as loading pointer values, checking shadow memory, and invalidating pointers. This segmentation allows the system to process multiple pointers simultaneously, improving throughput while maintaining safety.
2Reliability
If software-based pointer revocation methods are used to ensure temporal memory safety, then memory safety is improved, but memory usage increases
Solution Approach 1:
The patent introduces a hardware revocation engine with dedicated shadow memory that operates independently from the main memory system. This hardware-based approach uses specialized circuits and registers to track and revoke pointers, reducing the need for additional software data structures and minimizing overall memory consumption while maintaining safety guarantees.
3Productivity
If a hardware revocation engine with parallel pipeline is used, then performance impact is reduced, but device complexity increases
Solution Approach 1:
The revocation pipeline is integrated into the existing processor architecture, sharing resources such as the memory interface and operating in parallel with the main processor pipeline. This merging approach allows the system to benefit from hardware-accelerated pointer revocation while utilizing existing infrastructure, thereby reducing the overall complexity increase compared to a completely separate hardware system.
Data Source
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AI summary
A hardware revocation engine for invalidating a pointer, that refers to a deallocated object, from memory in a memory constrained system. The hardware revocation engine has a revocation pipeline coupled to a pipeline of a main processor of the memory constrained system. The revocation pipeline shares access to memory with the main pipeline, the revocation pipeline comprising at least a first stage and a subsequent second stage. In a first cycle of the revocation pipeline, the first stage of the revocation pipeline loads a first pointer-sized value from the memory. In a second cycle: the second stage checks whether the first loaded pointer-sized value is a pointer referring to deallocated memory. In a third cycle: in response to the outcome of the check indicating that the first loaded pointer-sized value is a pointer referring to deallocated memory, the first stage invalidates the first pointer-sized value.