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Milestone 8

Milestone 8 Status​

This milestone is planned.

Background​

OP-TEE requires support for NX, RO, RW permission expression for data in OP-TEE Core using the physical memory protections (PMP) as defined in the OpenSBI Domain Management Framework.  OP-TEE Core’s architecture-specific code responsible for expressing access attributes for code and data need to be extended for RISC-V

At present the Core and trusted application region is described in a single PMP unit in the OpenSBI Domain device tree settings.  OP-TEE Core’s .text and .data need different permission expressions using PMP.  OPTEE Core modifications are needed to put OP-TEE Core’s .text and .data sections into suitably separate address regions (from an NAPOT point of view).

Separating the core .text and .data sections into NAPOT-compatible regions allows the OpenSBI domain device tree to describe and enforce different access rights for each.

Milestone Description​

Milestone 8 gives OP-TEE core code and data distinct physical-memory permissions through the OpenSBI Domain Management Framework and RISC-V physical memory protection.

Requirements​

  • Express non-executable, read-only, and read-write data permissions for OP-TEE core through PMP.
  • Extend the RISC-V architecture-specific OP-TEE code that describes access attributes for code and data.
  • Place OP-TEE core .text and .data in separate address regions suitable for NAPOT representation.
  • Assign different permissions to the .text and .data regions.
  • Determine the start address and length of each region for use in the OpenSBI domain device tree.
  • Update the OpenSBI domain configuration to describe the separated regions and their permissions.
  • Validate that permitted accesses succeed and disallowed writes or instruction fetches are rejected.

Deliverables​

  • OP-TEE core layout changes that separate .text and .data into appropriately aligned regions.
  • An updated OpenSBI device tree describing the OP-TEE core regions and permissions.
  • Tests or documented procedures that verify the resulting access controls.