SWRU626 December 2025 CC3501E , CC3551E
When handling exceptions:
Software can configure the priorities of these interrupts. Exceptions can be specified as either Secure or Nonsecure. When an exception is taken the processor switches to the associated security state. The priority of Secure and Non-secure exceptions can be programmed independently. It is possible to deprioritize Nonsecure configurable exceptions using the AIRCR.PRIS bit field to enable Secure interrupts to take priority.
When taking and returning from an exception, the register state is always stored using the stack pointer associated with the background security state. When taking a Non-secure exception from Secure state, all the register state is stacked and then registers are cleared to prevent Secure data being available to the Non-secure handler. The vector base address is banked between Secure and Non-secure state. VTOR_S contains the Secure vector base address, and VTOR_NS contains the Non-secure vector base address. These registers can be programmed by software, and also initialized at reset by the system.