1. A system comprising: a secure processing system, including: a hardware memory protection unit (HMPU) comprising a shared memory, wherein the HMPU is configured to restrict access to the secure processing system, a secure memory configured to store a security policy, and a secure processor device configured to execute secure code, wherein the secure processor device is configured to determine, based on the security policy, whether to grant a request to access a secure service from the secure processing system; and a first processor device physically isolated from the secure processing system and a set of system peripherals, wherein the first processor device is configured to: execute code under the direction of the secure processor device, and place, in the shared memory, the request to access the secure service.