Domain Prediction Circuitry for Secure Memory Access Control
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Solution Overview
Problem
Data processing systems with multiple security domains face bottlenecks due to the need to determine the domain of operation before performing processing actions, leading to critical path issues and timing constraints.
Innovation Solution
The implementation of prediction circuitry to generate domain predictions for determining whether processing actions should be performed in a secure or less secure domain, allowing for access control using appropriate memory permissions and reducing critical path requirements through domain prediction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If domain determination is performed before processing actions, then security control is ensured, but processing speed and performance deteriorate due to critical path issues
Solution Approach 1:
The patent applies preliminary action by generating domain predictions in advance before the actual processing actions need to occur. The prediction circuitry predicts the domain (secure or less secure) ahead of time, allowing the system to prepare access control settings beforehand. This eliminates the need to determine domains on the critical path during actual processing, thus maintaining security control while improving processing speed.
2Measurement precision
If domain determination is performed before processing actions, then access control accuracy is improved, but timing constraints and critical path requirements worsen
Solution Approach 1:
The prediction circuitry performs domain determination in advance, generating predictions that are stored and used during actual processing. This preliminary action allows access control decisions to be made without adding timing constraints to the critical path, as the domain information is already available when processing occurs.
3Loss of time
If domain determination is delayed until needed, then timing constraints are reduced, but security control and access control accuracy deteriorate
Solution Approach 1:
Rather than delaying domain determination, the patent performs it preliminarily through prediction circuitry that generates domain predictions in advance. These predictions are then used during actual processing, ensuring security control is maintained without imposing timing constraints on the critical path.
Data Source
AI summary
A data processing apparatus supports operation in both a secure domain and a less secure domain. The secure domain has access to data that is not accessible when operating the less secure domain. Prediction circuitry generates a domain prediction indicating whether a given processing action (such as a memory access) is to be performed in association with the secure domain or with the less secure domain. In this way, an appropriate set of memory permission data for controlling access by different privilege levels in the domains may be selected and applied by an appropriate memory protection unit. If the domain prediction is incorrect, then the processing is stalled and the given processing action retried.