GCSPUSHM -- A64

GCSPUSHM

Guarded Control Stack push

This instruction decrements the current GCS pointer register by the size of a GCS procedure return record and stores an entry to the Guarded Control Stack.

For more information, see GCSPUSHM, Guarded Control Stack Push.

This is an alias of SYS. This means:

The encodings in this description are named to match the encodings of SYS.
The description of SYS gives the operational pseudocode, any constrained unpredictable behavior, and any operational information for this instruction.

System
(FEAT_GCS)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	0	1	0	1	0	1	0	0	0	0	1	0	1	1	0	1	1	1	0	1	1	1	0	0	0	Rt
										L			op1			CRn				CRm				op2

Encoding

GCSPUSHM <Xt>

is equivalent to

SYS #3, C7, C7, #0, <Xt>

and is always the preferred disassembly.

Assembler Symbols

<Xt>	Is the 64-bit name of the general-purpose source register, encoded in the "Rt" field.

Operation

The description of SYS gives the operational pseudocode for this instruction.

2026-03_rel 2026-03-26 20:48:11

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	0	1	0	1	0	1	0	0	0	0	1	0	1	1	0	1	1	1	0	1	1	1	0	0	0	Rt
										L			op1			CRn				CRm				op2

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	0	1	0	1	0	1	0	0	0	0	1	0	1	1	0	1	1	1	0	1	1	1	0	0	0	Rt
										L			op1			CRn				CRm				op2

GCSPUSHM

System(FEAT_GCS)

Encoding

Assembler Symbols

Operation

System
(FEAT_GCS)

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	0	1	0	1	0	1	0	0	0	0	1	0	1	1	0	1	1	1	0	1	1	1	0	0	0	Rt
										L			op1			CRn				CRm				op2