SoC Trace Probe Firewall for Cohort-Isolated Secure Debugging
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Solution Overview
Problem
Existing SoC debug architectures face challenges in balancing observability during trace-based debugging with security, as debug instruments can be exploited as backdoors for attacks, and fixed solutions are inflexible and unable to adapt to zonal architectures requiring virtualization and secure tracing over shared interconnects.
Innovation Solution
Implementing a software-based firewall at each interconnect trace probe with cohort ID-based filtering and a secure trace enable multiplexer to selectively enable packet access, ensuring that only authorized cohorts can trace data, thereby preventing unauthorized access to secure data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If debug instruments are added to facilitate trace-based debugging, then observability during debugging is improved, but security of the SoC deteriorates as debug instruments can be exploited as backdoors for attacks
Solution Approach 1:
The patent segments the SoC into multiple isolated cohorts, each with its own debug instruments and trace probes. This segmentation ensures that debug capabilities are distributed and isolated rather than centralized, preventing any single debug instrument from becoming a system-wide backdoor while maintaining individual observability for each cohort.
Solution Approach 2:
The patent introduces a security manager as an intermediary component that mediates between debug instruments and the SoC resources. The security manager authenticates and authorizes access to trace probes, acting as a buffer that prevents direct exploitation of debug instruments while maintaining debugging functionality.
2Object-affected harmful factors
If fixed configuration register values are used to tag assets with owner identification, then security is improved, but adaptability to zonal architectures requiring virtualization deteriorates
Solution Approach 1:
The patent replaces fixed configuration register values with dynamic cohort identification values that are assigned at runtime. Each cohort receives a unique identifier when created, allowing the same hardware infrastructure to adapt to different virtualized architectures and usage scenarios without requiring redesign of the security mechanism.
Solution Approach 2:
The patent creates a universal security manager that can manage multiple cohorts with different identifiers and access requirements through a single unified system. This multi-functional approach allows the same debug infrastructure to serve multiple zonal architectures and virtualization scenarios without requiring architecture-specific customization.
3Reliability
If fixed debug instrument solutions are used, then trace protection within specific nodes is provided, but flexibility to specify security features for all access use cases deteriorates
Solution Approach 1:
The patent segments trace protection into individual cohort-level security contexts managed by the security manager. Each cohort can have its own security policies and access rights defined independently, allowing flexible specification of security features for different access use cases while maintaining reliable trace protection for each segment.
4Measurement precision
If debug instruments are enabled for trace-based debugging, then observability is improved, but ability to prevent unauthorized access to secure data deteriorates
Solution Approach 1:
The security manager acts as an intermediary between trace probes and the data they observe. It intercepts access requests to secure data, authenticates the requesting cohort, and authorizes or denies access based on cohort identity and security policies, thereby preventing unauthorized access while maintaining observability for authorized cohorts.
Solution Approach 2:
The system implements feedback mechanisms where the security manager continuously monitors and responds to access requests based on cohort identifiers. When a cohort attempts to access trace data, the security manager receives the cohort ID, evaluates security policies, and provides feedback by allowing or blocking the access, creating a closed-loop security system.
Data Source
AI summary
An apparatus and method are disclosed for a System on Chip (SoC) which includes a central interconnect fabric connected between a plurality of initiators and targets, where the central interconnect includes one or more debug trace probes for connection to a debugger, where each debug trace probe is connected with debug firewall control logic configured to allow a data trace packet from a first cohort to be traced out to the debug trace probe only if the data trace packet includes a CID value associated with the first cohort that matches a CCID value associated with a configuring cohort which configures the debug trace probe, and where the debug firewall control logic includes a secure trace enable multiplexer connected to packet capture control logic which is configured to output a packet capture enable signal indicating whether the data trace packet is a secure packet or unsecure packet.