MRS	DBGBCR2_EL1, R22                   // b60230d5
	MRS	DBGBCR3_EL1, R8                    // a80330d5
	MRS	DBGBCR4_EL1, R2                    // a20430d5
	MRS	DBGBCR5_EL1, R4                    // a40530d5
	MRS	DBGBCR6_EL1, R2                    // a20630d5
	MRS	DBGBCR7_EL1, R6                    // a60730d5
	MRS	DBGBCR8_EL1, R1                    // a10830d5
	MRS	DBGBCR9_EL1, R16                   // b00930d5

// func getisar0() uint64
TEXT ·getisar0(SB),NOSPLIT,$0-8
	// get Instruction Set Attributes 0 into x0
	// mrs x0, ID_AA64ISAR0_EL1 = d5380600
	WORD	$0xd5380600
	MOVD	R0, ret+0(FP)
	RET

// func getisar1() uint64
TEXT ·getisar1(SB),NOSPLIT,$0-8
	// get Instruction Set Attributes 1 into x0
	// mrs x0, ID_AA64ISAR1_EL1 = d5380620
	WORD	$0xd5380620
	MOVD	R0, ret+0(FP)
	RET

// func getpfr0() uint64

	MRS	ICC_EOIR1_EL1, R5                                // ERROR "system register is not readable"
	MRS	ICC_EOIR0_EL1, R5                                // ERROR "system register is not readable"
	MRS	ICC_DIR_EL1, R5                                  // ERROR "system register is not readable"
	MRS	ICC_ASGI1R_EL1, R5                               // ERROR "system register is not readable"

	"MOVH",
	"MOVHU",
	"MOVK",
	"MOVKW",
	"MOVN",
	"MOVNW",
	"MOVP",
	"MOVPD",
	"MOVPQ",
	"MOVPS",
	"MOVPSW",
	"MOVPW",
	"MOVW",
	"MOVWU",
	"MOVZ",
	"MOVZW",
	"MRS",
	"MSR",
	"MSUB",
	"MSUBW",
	"MUL",
	"MULW",
	"MVN",
	"MVNW",
	"NEG",
	"NEGS",
	"NEGSW",
	"NEGW",
	"NGC",
	"NGCS",
	"NGCSW",
	"NGCW",
	"NOOP",
	"ORN",

TEXT runtime·getCntxct(SB),NOSPLIT,$0
	MOVB	physical+0(FP), R0
	CMP	$0, R0
	BEQ	3(PC)

	// get CNTPCT (Physical Count Register) into R0
	MRS	CNTPCT_EL0, R0
	B	2(PC)

	// get CNTVCT (Virtual Count Register) into R0
	MRS	CNTVCT_EL0, R0

	MOVW	R0, ret+8(FP)
	RET

// func issetugid() int32
TEXT runtime·issetugid(SB),NOSPLIT|NOFRAME,$0
	MOVD $SYS_issetugid, R8
	SVC

	MSR $1, SPSel                              // bf4100d5
	MSR $9, DAIFSet                            // df4903d5
	MSR $6, DAIFClr                            // ff4603d5
	MRS ELR_EL1, R8                            // 284038d5
	MSR R16, ELR_EL1                           // 304018d5
	MRS DCZID_EL0, R3                          // e3003bd5
	MSUBW R1, R1, R12, R5                      // 8585011b
	MSUB R19, R16, R26, R2                     // 42c3139b

		o2 |= LSL0_64

	case 35: /* mov SPR,R -> mrs */
		o1 = c.oprrr(p, AMRS)

		// SysRegEnc function returns the system register encoding and accessFlags.
		_, v, accessFlags := SysRegEnc(p.From.Reg)
		if v == 0 {
			c.ctxt.Diag("illegal system register:\n%v", p)
		}
		if (o1 & (v &^ (3 << 19))) != 0 {
			c.ctxt.Diag("MRS register value overlap\n%v", p)
		}
		if accessFlags&SR_READ == 0 {