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