Apparatus and method for managing processor configuration data

A method of managing processor configuration data in a data processing apparatus comprising a processor operable in a plurality of modes and a plurality of domains, said plurality of domains comprising a secure domain and a non-secure domain, said plurality of modes including at least one non-secure mode being a mode in the non-secure domain, at least one secure mode being a mode in the secure domain, and a monitor mode, said processor being operable such that when executing a program in a secure mode said program has access to secure data which is not accessible when said processor is operating in a non-secure mode, said method comprising the steps of:

• executing on said processor at least partially in said monitor mode a monitor program to manage switching between said secure domain and said non-secure domain, including performing the step of switching the processor configuration data between secure processor configuration data and non-secure processor configuration data;
• when in said monitor mode, said monitor program using monitor mode specific processor configuration data, thereby ensuring that operation of the processor in said monitor mode is unaffected by the switching of the processor configuration data.

A computer program operable to configure a processor in a data processing apparatus to manage processor configuration data, the processor being operable in a plurality of modes and a plurality of domains, said plurality of domains comprising a secure domain and a non-secure domain, said plurality of modes including at least one non-secure mode being a mode in the non-secure domain, at least one secure mode being a mode in the secure domain, and a monitor mode, said processor being operable such that when executing a program in a secure mode said program has access to secure data which is not accessible when said processor is operating in a non-secure mode, said computer program being operable to perform the steps of:

• whilst at least partially in said monitor mode, managing switching between said secure domain and said non-secure domain, including performing the step of switching the processor configuration data between secure processor configuration data and non-secure processor configuration data;
• and
• when in said monitor mode, using monitor mode specific processor configuration data, thereby ensuring that operation of the processor in said monitor mode is unaffected by the switching of the processor configuration data.