SP_EL3 Stack Pointer (EL3) when EL3 is implemented and FEAT_AA64 is implemented Holds the stack pointer associated with EL3. The value of SPSel.SP determines the current stack pointer. Special SP_EL3 is a 64-bit register. StackPointer Stack pointer 63 0 63:0 Stack pointer. AU This register is not accessible using MRS and MSR instructions. When the value of SPSel.SP is 1, this register is accessible at EL3 as the current stack pointer. When the value of SPSel.SP is 0, SP_EL0 is used as the current stack pointer at all Exception levels. 2026-03-26 20:27:25 2026-03_rel