Intel 253666-024US - Manual (Page 546)

3-500 Vol. 2A IRET/IRETD—Interrupt Return
INSTRUCTION SET REFERENCE, A-M
If the stack segment selector RPL is not equal to the RPL of the
return code segment selector.
#SS(0) If an attempt to pop a value off the stack violates the SS limit.
If an attempt to pop a value off the stack causes a non-canonical
address to be referenced.
#NP(selector) If the return code or stack segment is not present.
#PF(fault-code) If a page fault occurs.
#AC(0) If an unaligned memory reference occurs when the CPL is 3 and
alignment checking is enabled.
#UD If the LOCK prefix is used.