6.5.1. Exception handling instructions

There are three exception handling instructions whose purpose it is to cause an exception to be taken. These are used to make a call to code that runs in a higher Exception level in the OS (EL1), the Hypervisor (EL2), or Secure Monitor (EL3):

The immediate value is made available to the handler in the Exception Syndrome Register. This is a change from ARMv7, where the immediate value had to be determined by reading the opcode of the calling instruction. See Chapter 10 AArch64 Exception Handling for further information.

To return from an exception, use the ERET instruction. This instruction restores processor state by copying SPSR_ELn to PSTATE and branches to the saved return address in ELR_ELn.

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