Peripheral Device Protection Circuit for Data Processing Apparatus

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Solution Overview

Problem

Existing data processing systems face reliability issues due to the need for individual access control settings for each program, which can be error-prone and vulnerable to hardware errors, especially when untrusted programs are involved, leading to potential malfunctions and reduced system reliability.

Innovation Solution

A data processing apparatus with an arithmetic circuit operating at multiple authority levels and a peripheral device protection circuit that uses dual preset values for access control, where the higher-level preset value overrides lower-level settings, ensuring access permissions or denials are determined based on both values, thereby enhancing system reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If individual access control settings are performed for each program, then access control precision is improved, but system reliability deteriorates due to error-prone settings and hardware errors

Engineering Contradiction:

Improveaccess control precisionVSAvoidsystem reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by establishing a higher-level protection preset value that serves as a safety net. This higher-level setting is configured in advance to override lower-level settings, providing a compensatory mechanism that prevents system failure when errors occur in individual program settings or due to hardware errors.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The patent changes the parameter of protection level by introducing a hierarchical structure with multiple preset values at different protection levels. The higher-level preset value acts as an override mechanism, changing the effective protection parameter when errors are detected or when higher security is required, thus maintaining reliability while preserving access control precision.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If access control settings are stored in registers, then ease of operation is improved, but reliability deteriorates due to vulnerability to hardware errors and soft errors

Engineering Contradiction:

Improveease of settingVSAvoidsetting stability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies beforehand cushioning by storing multiple preset values at different protection levels, with the higher-level value serving as a backup that activates when hardware errors or soft errors affect the lower-level settings. This compensatory structure maintains ease of operation while protecting against reliability issues.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The higher-level protection preset value acts as an intermediary layer between the arithmetic circuit and the peripheral devices. It mediates the access control decisions, overriding potentially erroneous lower-level settings and ensuring reliable operation even when register contents are compromised by hardware or soft errors.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If untrusted programs are supplied by multiple vendors, then adaptability is improved, but reliability deteriorates due to likely errors in access control settings

Engineering Contradiction:

Improveprogram compatibilityVSAvoidaccess control reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies universality by establishing a higher-level protection preset value that universally applies to all programs regardless of vendor or source. This higher-level setting serves as a common safety mechanism that works across all untrusted programs, maintaining adaptability while ensuring reliable access control through the override capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The higher-level protection preset value is configured in advance as a universal safety net that compensates for potential errors in access control settings from any vendor. This beforehand cushioning mechanism ensures that even when untrusted programs contain errors, the system maintains reliability through the higher-level override setting.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Data Source

PatentUS8209448B2Data processing apparatus and method of protecting a peripheral device in data processing apparatus

Publication Date: 2012.06.26 RENESAS ELECTRONICS CORP

AI summary

A data processing apparatus includes an arithmetic circuit and a peripheral device protection circuit that controls access of the arithmetic circuit to the peripheral devices. The peripheral device protection circuit has a first protection preset value and a second protection preset value set as a protection level higher than that of the first protection preset value. The peripheral device protection circuit includes: a setting selection circuit that generates access permission/denial information by referring to the first protection preset value and the second protection preset value when the arithmetic circuit operates at a first operation authority level, or by referring to the second protection preset value when the arithmetic circuit operates at the second operation authority level. An access protection circuit that determines permission/denial of access to the peripheral devices based on access information output from the arithmetic circuit and the access permission/denial information.