Interrupt Handling
==================

Interrupt handling in Cheriette uses a vector table at EL2, which sets up a
secure call return capability to the interrupted task, 
and then calls the interrupt handler as if it had been called by a normal secure call.

When the interrupt handler returns, it does so thorugh the secure call
primitive and returns directly to the interrupted task.

User space tasks can register interrupts using a system call,
and must provide a stack that the interrupt handler is executed with.