OP-TEE: REE filesystem TA

⚠️ The code is based on: https://gitlab.com/riseproject/riscv-optee/optee_os/-/tree/dev-optee-mpxy

Commit ID: 75df9ba41a404aec897399ead0ff0aebcbff48ca

• Reference:

  Trusted Applications — OP-TEE documentation documentation

• ree_fs_ta_open()
  • Call rpc_load() to request TA from tee-supplicant.
  • Validate the loaded TA.
• rpc_load()
  • Call thread_rpc_cmd() with OPTEE_RPC_CMD_LOAD_TA RPC command without struct thread_param_memref parameter to request the size of TA.
    • OPTEE_RPC_CMD_LOAD_TA RPC command is saved to struct optee_msg_arg.cmd.
    • struct optee_msg_arg is stored in the shared memory shared with the untrusted domain.
  • Call thread_rpc_alloc_payload() to allocate data for TA.
    • Call thread_rpc_alloc() to allocate shared memory for TA.
      • Call thread_rpc() with rpc_args (rv[THREAD_RPC_NUM_ARGS]). rpc_args’s first element is set to OPTEE_ABI_RETURN_RPC_CMD function. The RPC command is set to OPTEE_RPC_CMD_SHM_ALLOC to allocate the shared memory for TA.
  • Call thread_rpc_cmd() with OPTEE_RPC_CMD_LOAD_TA RPC command again with struct thread_param_memref parameter to load TA.