gcsstr

Guarded Control Stack Store

GCSSTR <Xt>, [<Xn|SP>]

Stores a value to the GCS (Control Flow Integrity).

Pseudocode Operation

No pseudocode available.

Encoding

Binary Layout

11011001000111110

31:15

000

14:12

11:10

9:5

4:0

Format Load/Store

Opcode 0xD91F0C00

Extension FEAT_GCS

Reference

View in Arm A64 ISA Reference ↗ Arm A64 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xD91F0C00	GCSSTR <Xt>, [<Xn\|SP>]		A64		11011001000111110 \| 000 \| 11 \| Rn \| Rt

Description

Guarded Control Stack Store stores a doubleword from a register to memory. The address that is used for the store is calculated from a base register.

Operation

bits(64) address;
bits(64) data;

bits(2) effective_el = PSTATE.EL;

if effective_el == PSTATE.EL then
    CheckGCSSTREnabled();

AccessDescriptor accdesc = CreateAccDescGCS(effective_el, MemOp_STORE);

if n == 31 then
    CheckSPAlignment();
    address = SP[];
else
    address = X[n, 64];

data = X[t, 64];
Mem[address, 8, accdesc] = data;