Linear Address Tag Table Hardware Memory Isolation
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Solution Overview
Problem
Current computer processors lack effective memory isolation between software components, leading to security vulnerabilities where a bug in one component can compromise the entire application, and existing solutions like process isolation result in performance and memory overhead.
Innovation Solution
Implementing a linear address tag table (LATT) that extends page table lookups with metadata tags, allowing hardware-enforced memory isolation between components within the same address space, using a sandbox instruction set architecture to ensure memory access tags match the current sandbox ID and raising faults for mismatches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If process isolation is used to isolate software components, then security is improved, but memory overhead and performance latency increase
Solution Approach 1:
The patent divides the address space into compartments using a compartment identifier (CID) that is integrated into the address translation structure. Each software component is assigned a specific CID, creating logical segmentation without requiring separate process address spaces. This allows multiple components to coexist in the same address space with hardware-enforced isolation, eliminating the memory overhead of process isolation while maintaining security boundaries.
Solution Approach 2:
The patent nests the compartment identifier within the existing page table structure by integrating it into the translation lookaside buffer (TLB) entries and address translation logic. The CID is embedded alongside traditional page table information, creating a nested structure where compartmentalization metadata is contained within the existing memory management framework. This avoids the need for separate isolation mechanisms and reduces overall system overhead.
2Reliability
If process isolation is used to isolate software components, then security is improved, but performance latency increases
Solution Approach 1:
The patent implements fine-grained compartmentalization at the component level rather than process level, allowing each software component to have its own security boundary within the same address space. This segmentation enables more efficient resource sharing and reduces the overhead of context switching and address space management, thereby improving performance latency while maintaining security isolation.
Solution Approach 2:
The patent merges compartmentalization functionality directly into the existing address translation and memory management hardware structures, such as the TLB and page tables. By combining security enforcement with standard memory management operations, the system avoids additional latency from separate isolation checks, as the compartment identifier is validated as part of the normal address translation process.
3Device complexity
If traditional page tables are used without metadata tags, then address translation is simple, but memory isolation between components is not enforced
Solution Approach 1:
The patent makes the address translation structure multi-functional by integrating both traditional page table functionality and compartmentalization enforcement into the same hardware structures. The translation lookaside buffer and page tables simultaneously handle address translation and compartment identifier validation, eliminating the need for separate isolation mechanisms while maintaining security boundaries between software components.
Solution Approach 2:
The patent nests the compartment identifier metadata within the existing page table entry structure, embedding security information alongside traditional translation data. This nested approach allows the address translation hardware to enforce memory isolation without requiring a completely separate metadata structure, thereby maintaining relative simplicity while adding enforcement capability.
Data Source
AI summary
An apparatus and method for memory management using compartmentalization. For example, one embodiment of a processor comprises: execution circuitry to execute instructions and process data, at least one instruction to generate a system memory access request using a first linear address; and address translation circuitry to perform a first walk operation through a set of one or more address translation tables to translate the first linear address to a first physical address, the address translation circuitry to concurrently perform a second walk operation through a set of one or more linear address metadata tables to identify metadata associated with the linear address, and to use one or more portions of the metadata to validate access by the at least one instruction to the first physical address.