User

usr

The normal ARM program execution mode

FIQ

fiq

Used for most performance-critical interrupts in a system

IRQ

irq

Used for general-purpose interrupt handling

Supervisor

svc

Protected mode for the operating system

Abort mode

abt

Entered after a Data Abort or instruction Prefetch Abort

System

sys

A privileged User mode for the operating system

Undefined

und

Entered when an Undefined Instruction is executed