Exception Vector Table Selection Using Processor Operating Mode

A method, comprising:

• operating, by a processor circuit, in a current processor mode of a plurality of processor modes, wherein the current processor mode indicates a particular set of memory access permissions;
• receiving, by the processor circuit, an indication of an assertion of a particular exception signal of a plurality of exception signals;
• selecting, by the processor circuit using a determined processor mode of the plurality of processor modes, one vector table of a plurality of vector tables;
• identifying, by the processor circuit, a particular exception vector of a plurality of exception vectors in the selected vector table;
• and
• issuing, by the processor circuit using the identified particular exception vector, a request for a first instruction of an exception handler routine.

A non-transitory, computer-readable storage medium storing program instructions that include one or more instances of an instruction that is executable by a processor circuit of a computer system to request an agent transition including a change from a current value of an agent index to a new value, a value of the agent index being indicative of a software agent that is currently executing on the processor circuit, wherein execution of a particular instance of the instruction causes the processor circuit to:

• assert a particular exception signal of a plurality of exception signals;
• based on a particular value of the agent index, determine one vector table of a plurality of vector tables to access;
• based on the particular exception signal, access a particular exception vector from the one vector table;
• and
• fetch a first instruction located at an address identified by the particular exception vector.