Execution Limiting Circuitry for Privilege-Aware Instruction Control
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Solution Overview
Problem
Existing data processing systems lack effective mechanisms to control and limit the execution capabilities of software at different privilege levels without creating additional execution levels, processes, or page tables, which can compromise security and resource access.
Innovation Solution
An apparatus and method that utilize an access control register to apply execution controls of a less privileged level for specific functionalities, using limitation circuitry to restrict register and instruction access without affecting the active execution level, through configuration values and context-aware permission management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional execution levels, processes, or page tables are created to control software execution capabilities, then security and resource access control are improved, but device complexity and system overhead increase
Solution Approach 1:
The patent extracts the limitation functionality from the execution level structure itself, creating a separate limitation circuitry that can independently restrict software capabilities without modifying the execution level hierarchy. This allows security controls to be applied by removing specific capabilities rather than adding complex execution levels.
Solution Approach 2:
The patent segments the control mechanism into a dedicated limitation circuitry that operates independently from the execution level circuitry. This segmentation allows fine-grained control over specific functionalities (register access, instruction execution) without affecting the overall execution level structure or requiring additional page tables.
2Reliability
If additional execution levels are created to limit software capabilities, then access control is improved, but loss of time and processing overhead increase
Solution Approach 1:
The limitation circuitry is configured to apply restrictions proactively before unauthorized access attempts occur. By pre-defining which functionalities are restricted for each software instance, the system prevents security violations before they can impact performance or require time-consuming intervention.
Solution Approach 2:
The limitation circuitry autonomously enforces capability restrictions without requiring intervention from execution level transitions or additional processing layers. The circuitry self-manages the restriction of register access and instruction execution based on configured parameters, eliminating the need for time-consuming checks at multiple execution levels.
3Reliability
If execution controls are applied by changing active execution level, then security is improved, but adaptability and flexibility are reduced
Solution Approach 1:
The limitation circuitry provides dynamic capability restriction that can be independently configured for different software instances without changing their execution levels. This allows the system to adaptively control access to specific functionalities (registers, instructions) while maintaining the flexibility of the existing execution level structure for other operations.
Data Source
AI summary
An apparatus is provided that includes an access control register that stores a configuration value and processing circuitry executes instructions. Execution level circuitry applies execution limits of an active execution level for a functionality. Limitation circuitry applies one or more execution limits of a less privileged execution level than the active execution level for the functionality, without affecting the active execution level, in response to the configuration value being a particular value.