SPRSP93 November 2024 F29H850TU , F29H859TU-Q1
ADVANCE INFORMATION
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A simplified view of the F29x Real-Time Security architecture in this device is shown in Figure 7-12. At the heart of the architecture is the Safety and Security Unit (SSU). The SSU acts as a firewall between the C29 CPUs and the memory and peripherals. The primary role of the SSU is to enforce user access protection policy every time the C29 CPU performs accesses to peripherals and memory on the chip. In addition, the SSU governs debug access and Flash Controller operations in the C29 application subsystem (note: the SSU has no control over the HSM Flash, or any other HSM resources). While the Hardware Security Module (HSM) provides cryptographic services and governs authentication, secure boot and secure key/code provisioning, the SSU is responsible for run-time safety and security protections in application CPU subsystems. Both the HSM and SSU govern debug access authorization; both must enable access to a specific resource for debug to be authorized.
The SSU is tightly coupled to the C29 CPUs and the Flash Controller. Each C29 CPU is designed to support hardware function isolation and protections using memory protection identifiers (LINKs), safety and security isolation contexts (STACKs), and debug access ZONEs. An example of a system SSU configuration, showing the relationship between access protection ranges, LINKs, STACKs and ZONEs is shown in Figure 7-13. When the CPU requests an instruction fetch, the SSU first decodes the instruction address to a LINK, STACK, and ZONE, and then passes that information back to the CPU along with the fetched data. The CPU retains this security context information together with the instruction throughout the execution pipeline, and passes the context along to the SSU when making a data memory read or write access.