Memory Address Decoding Prioritization for Security
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Solution Overview
Problem
In computer systems, overlapping memory address ranges can lead to unpredictable behavior and compromise security by allowing unauthorized access to privileged software and hardware modules, as existing address decoding methods lack a systematic prioritization mechanism.
Innovation Solution
Introducing a system-wide decoding priority value for base address registers, which dictates the order of address decoding operations, ensuring that the highest priority register is used for decoding, even in cases of overlapping ranges, and allowing configuration by firmware or privileged software for enhanced security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If overlapping memory address ranges are assigned to various devices, then device flexibility and adaptability are improved, but system reliability and security are worsened due to unpredictable behavior and unauthorized access
Solution Approach 1:
The patent applies local quality by assigning different decoding priorities to different base address registers based on the security sensitivity of each device. Critical devices like SMM and SGX receive higher priorities while less critical devices receive lower priorities. This localized differentiation maintains the flexibility to assign overlapping ranges while ensuring predictable decoding behavior for security-critical regions, thus resolving the contradiction between adaptability and reliability.
2Device complexity
If existing address decoding methods are used without prioritization, then device complexity is reduced, but security is worsened due to lack of protection against memory remapping attacks
Solution Approach 1:
The patent implements preliminary action by pre-configuring decoding priorities for base address registers during system initialization. The firmware or privileged software establishes the priority order before any memory access occurs, so that when overlapping addresses are encountered, the highest priority register is automatically selected without requiring complex real-time arbitration logic. This preliminary setup enhances security against memory remapping attacks while keeping the decoding mechanism relatively simple.
3Object-affected harmful factors
If highest priority is always assigned to SMM register, then security is improved by preventing unauthorized access, but adaptability is worsened due to restricted memory range configuration
Solution Approach 1:
The patent applies dynamics by making the priority assignment configurable rather than fixed. The firmware or privileged software can dynamically adjust which base address registers receive highest priorities based on the specific security requirements and memory mapping needs of different systems. This dynamic configurability allows the system to maintain strong security protection for critical regions like SMM and SGX while still providing the flexibility to adapt to different hardware configurations and security scenarios.
Data Source
AI summary
System and methods for address decoding prioritization. An example processing system may comprise: a plurality of base address registers, wherein each base address registers specifies an address range and a decoding priority associated with the address range; and an address decoding circuit coupled to the plurality of base address registers, the address decoding circuit to: receive a memory address identified by a memory access transaction, and produce a decoded address by decoding the memory address using the plurality of base address registers in an order of respective decoding priorities.