GCSPOPCX Guarded Control Stack Pop and Compare exception return record when FEAT_GCS is implemented and FEAT_AA64 is implemented Loads a GCS exception return record from the location indicated by the current GCS pointer register, compares the values loaded with the current ELR_ELx, SPSR_ELx, and LR, and increments the current GCS pointer register by the size of a GCS exception return record. GCSE Instructions GCSPOPCX is a 64-bit System instruction. Rt should be encoded as 0b11111. If the Rt field is not set to 0b11111, it is CONSTRAINED UNPREDICTABLE whether: The instruction is UNDEFINED. The instruction behaves as if the Rt field is set to 0b11111. This system instruction is an alias of the SYS instruction. GCSPOPCX if !(IsFeatureImplemented(FEAT_GCS) && IsFeatureImplemented(FEAT_AA64)) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if IsFeatureImplemented(FEAT_GCS) && GetCurrentEXLOCKEN() && !Halted() && PSTATE.EXLOCK == '1' then EXLOCKException(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3().FGTEn == '1') && HFGITR_EL2().nGCSEPP == '0' then AArch64_SystemAccessTrap(EL2, 0x18); elsif GCSEnabled(EL1) then GCSPOPCX(); end; elsif PSTATE.EL == EL2 then if IsFeatureImplemented(FEAT_GCS) && GetCurrentEXLOCKEN() && !Halted() && PSTATE.EXLOCK == '1' then EXLOCKException(); elsif GCSEnabled(EL2) then GCSPOPCX(); end; elsif PSTATE.EL == EL3 then if IsFeatureImplemented(FEAT_GCS) && GetCurrentEXLOCKEN() && !Halted() && PSTATE.EXLOCK == '1' then EXLOCKException(); elsif GCSEnabled(EL3) then GCSPOPCX(); end; end; 2026-03-26 20:27:25 2026-03_rel