GCSPOPCX

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GCSPOPCX, Guarded Control Stack Pop and Compare exception return record

Purpose

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.

Configuration

This instruction is present only when FEAT_GCS is implemented and FEAT_AA64 is implemented. Otherwise, direct accesses to GCSPOPCX are UNDEFINED.

Attributes

Field descriptions

Executing GCSPOPCX

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.

Accesses to this instruction use the following encodings in the System instruction encoding space:

GCSPOPCX

op0	op1	CRn	CRm	op2
0b01	0b000	0b0111	0b0111	0b101

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;