Apparatus and method for handling exceptions

A method of handling exceptions within an apparatus, comprising:

• executing, on processing circuitry operable in one of a plurality of security domains comprising at least a secure domain and a less secure domain, program code that includes a plurality of exception handling routines executed in response to corresponding exceptions;
• storing in a plurality of registers data for access by the processing circuitry when executing the program code, the plurality of registers comprising a first subset of registers and a second subset of registers non-overlapping with the first subset of registers;
• employing exception control circuitry, in response to occurrence of a given exception from background processing, to trigger a state saving operation to save data from the plurality of registers before triggering the processing circuitry to execute a given exception handling routine corresponding to the given exception;
• storing configuration information used to categorize exception handling routines within the plurality of exception handling routines;
• determining with reference to the configuration information whether the given exception handling routine is of a first category or a second category within the one of the plurality of security domains that the given exception handling routine will be executed in;
• and, causing the exception control circuitry, when triggering the state saving operation, to trigger saving the data from the first subset of registers when the given exception handling routine is of the first category, and to trigger saving the data from both the first subset and the second subset of registers when the given exception handling routine is of the second category;
• wherein determining with reference to the configuration information whether the given exception handling routine is of the first category or the second category is independent of whether any change in security domain will occur when transitioning from the background processing to execution of the given exception handling routine.

A non-transitory computer-readable medium storing a computer program for controlling a host data processing apparatus to provide an instruction execution environment, comprising:

• processing program logic, operable in one of a plurality of security domains comprising at least a secure domain and a less secure domain, to execute program code that includes a plurality of exception handling routines executed in response to corresponding exceptions;
• data structure emulating program logic to maintain a plurality of register data structures to store data for access by the processing program logic when executing the program code, the plurality of register data structures comprising a first subset of data structures and a second subset of data structures non-overlapping with the first subset of data structures;
• and exception control program logic, responsive to occurrence of a given exception from background processing, to trigger a state saving operation to save data from the plurality of register data structures before triggering the processing program logic to execute a given exception handling routine corresponding to the given exception;
• wherein the data structure emulating program logic is further configured to maintain a configuration data structure to store configuration information used to categorize exception handling routines within the plurality of exception handling routines;
• and, wherein the exception control program logic is configured to determine with reference to the configuration information whether the given exception handling routine is of a first category or a second category within the one of the plurality of security domains that the given exception handling routine will be executed in, and is configured, when triggering the state saving operation, to trigger saving the data from the first subset of data structures when the given exception handling routine is of the first category, and to trigger saving the data from both the first subset and the second subset of data structures when the given exception handling routine is of the second category;
• and
• the exception control program logic is configured to determine with reference to the configuration information whether the given exception handling routine is of the first category or the second category independent of whether any change in security domain will occur when transitioning from the background processing to execution of the given exception handling routine.