SCTLR2

When the Effective value of HCR_EL2.{E2H, TGE} is {1, 1}, these controls also apply to execution at EL0.

Configuration

This register is present only when FEAT_SCTLR2 is implemented. Otherwise, direct accesses to SCTLR2_EL2 are UNDEFINED.

This register has no effect if EL2 is not enabled in the current Security state.

Attributes

Field descriptions

Bits [63:13]

CPTM0, bit [12]
When FEAT_CPA2 is implemented and the Effective value of HCR_EL2.E2H is 1:

This field controls unprivileged Checked Pointer Arithmetic for Multiplication.

CPTM0	Meaning
0b0	Pointer Arithmetic for Multiplication is not checked.
0b1	Pointer Arithmetic for Multiplication is checked.

If HCR_EL2.TGE == 0b0, the field is IGNORED for all purposes other than direct reads and writes of the register.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

If the Effective value of SCTLR2_EL2.CPTA0 is 0, then the Effective value of this field is 0.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

CPTM, bit [11]
When FEAT_CPA2 is implemented:

This field controls Checked Pointer Arithmetic for Multiplication at EL2.

CPTM	Meaning
0b0	Pointer Arithmetic for Multiplication is not checked.
0b1	Pointer Arithmetic for Multiplication is checked.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

If the Effective value of SCTLR2_EL2.CPTA is 0, then the Effective value of this field is 0.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

CPTA0, bit [10]
When FEAT_CPA2 is implemented and the Effective value of HCR_EL2.E2H is 1:

This field controls unprivileged Checked Pointer Arithmetic for Addition.

CPTA0	Meaning
0b0	Pointer Arithmetic for Addition is not checked.
0b1	Pointer Arithmetic for Addition is checked.

If HCR_EL2.TGE == 0b0, the field is IGNORED for all purposes other than direct reads and writes of the register.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

CPTA, bit [9]
When FEAT_CPA2 is implemented:

Otherwise:

EnPACM0, bit [8]
When FEAT_PAuth_LR is implemented and the Effective value of HCR_EL2.E2H is 1:

PACM Enable at EL0. Controls the effect of a PACM instruction at EL0.

EnPACM0	Meaning
0b0	The effects of PACM are disabled at EL0.
0b1	A PACM instruction at EL0 causes PSTATE.PACM to be set to 0b1.

If HCR_EL2.TGE == 0b0, the field is IGNORED for all purposes other than direct reads and writes of the register.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

EnPACM, bit [7]
When FEAT_PAuth_LR is implemented:

EnPACM	Meaning
0b0	The effects of PACM are disabled at EL2.
0b1	A PACM instruction at EL2 causes PSTATE.PACM to be set to 0b1.

Otherwise:

EnIDCP128, bit [6]
When FEAT_SYSREG128 is implemented:

Enables access to IMPLEMENTATION DEFINED 128-bit System registers.

EnIDCP128	Meaning
0b0	Accesses at EL0 to IMPLEMENTATION DEFINED 128-bit System registers are trapped to EL2 using an ESR_EL2.EC value of 0x14, unless the access generates a higher priority exception. Disables the functionality of the 128-bit IMPLEMENTATION DEFINED System registers that are accessible at EL2.
0b1	No accesses are trapped by this control.

EnIDCP128

Meaning

0b0

Accesses at EL0 to IMPLEMENTATION DEFINED 128-bit System registers are trapped to EL2 using an ESR_EL2.EC value of 0x14, unless the access generates a higher priority exception.

Disables the functionality of the 128-bit IMPLEMENTATION DEFINED System registers that are accessible at EL2.

0b1

No accesses are trapped by this control.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

EASE, bit [5]
When FEAT_DoubleFault2 is implemented:

External Aborts to SError exception vector.

EASE	Meaning
0b0	Synchronous External abort exceptions taken to EL2 are taken to the appropriate synchronous exception vector offset from VBAR_EL2.
0b1	Synchronous External abort exceptions taken to EL2 are taken to the appropriate SError exception vector offset from VBAR_EL2.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

EnANERR, bit [4]
When FEAT_ANERR is implemented:

Enable Asynchronous Normal Read Error.

EnANERR	Meaning
0b0	External aborts on Normal memory reads generate synchronous Data Abort exceptions in the EL2 and EL2&0 translation regimes.
0b1	External aborts on Normal memory reads generate synchronous Data Abort or asynchronous SError exceptions in the EL2 and EL2&0 translation regimes.

It is implementation-specific whether this field applies to memory reads generated by each of the following:

When FEAT_SME is implemented:
- SVE register loads when the PE is in Streaming SVE mode.
- SME register loads.
When FEAT_LSE is implemented, LD<op>, SWP and CAS{P} Atomic instructions that return a value to the PE.
When FEAT_LS64_V is implemented, LD64B and ST64BV{0} instructions that return a value to the PE.
When FEAT_THE is implemented, RCW instructions that return a value to the PE.

Setting this field to 0 does not guarantee that the PE is able to take a synchronous Data Abort exception for an External abort on a Normal memory read in every case. There might be implementation-specific circumstances when an error on a load cannot be taken synchronously. These circumstances should be rare enough that treating such occurrences as fatal does not cause a significant increase in failure rate.

If FEAT_SVE is implemented, SCTLR2_EL2.EnADERR is 0, and the access generating the External abort is due to any Active element of an SVE Non-fault vector load instruction or an Active element that is not the first Active element of an SVE First-fault vector load instruction, then no exception is generated and the External abort is reported in the FFR.

Setting this field to 0 might have a performance impact for Normal memory reads.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

Otherwise, this field is ignored by the PE and treated as one when all of the following are true:

FEAT_ADERR is implemented.
ID_AA64MMFR3_EL1.ANERR reads as 0b0010.
SCTLR2_EL2.EnADERR is 1.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

EnADERR, bit [3]
When FEAT_ADERR is implemented:

Enable Asynchronous Device Read Error.

EnADERR	Meaning
0b0	External aborts on Device memory reads generate synchronous Data Abort exceptions in the EL2 and EL2&0 translation regimes.
0b1	External aborts on Device memory reads generate synchronous Data Abort or asynchronous SError exceptions in the EL2 and EL2&0 translation regimes.

It is implementation-specific whether this field applies to memory reads generated by each of the following:

SIMD&FP register loads.
When FEAT_SVE is implemented, SVE register loads.
When FEAT_SME is implemented, SME register loads.
When FEAT_LSE is implemented, LD<op>, SWP and CAS{P} Atomic instructions that return a value to the PE.
When FEAT_LS64_V is implemented, LD64B and ST64BV{0} instructions that return a value to the PE.
When FEAT_THE is implemented, RCW instructions that return a value to the PE.

Setting this field to 0 does not guarantee that the PE is able to take a synchronous Data Abort exception for an External abort on a Device memory read in every case. There might be implementation-specific circumstances when an error on a load cannot be taken synchronously. These circumstances should be rare enough that treating such occurrences as fatal does not cause a significant increase in failure rate.

Setting this field to 0 might have a performance impact for Device memory reads.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

Otherwise, this field is ignored by the PE and treated as one when all of the following are true:

FEAT_ANERR is implemented.
ID_AA64MMFR3_EL1.ADERR reads as 0b0010.
SCTLR2_EL2.EnANERR is 1.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

NMEA, bit [2]
When FEAT_DoubleFault2 is implemented:

Non-maskable External Aborts. Controls whether PSTATE.A masks SError exceptions at EL2.

NMEA	Meaning
0b0	SError exceptions are not taken at EL2 if PSTATE.A == 1, unless routed to a higher Exception level.
0b1	SError exceptions are taken at EL2 regardless of the value of PSTATE.A, unless routed to a higher Exception level.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

EMEC, bit [1]
When FEAT_MEC is implemented:

Enables MEC. When enabled, memory accesses to the Realm physical address space are associated with a MECID.

EMEC	Meaning
0b0	MEC is not enabled for the Realm physical address space.
0b1	MEC is enabled for the Realm physical address space.

This bit is permitted to be cached in a TLB.

When EL3 is implemented and SCR_EL3.SCTLR2En == 0, this field is ignored by the PE and treated as zero.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

Bit [0]

Accessing SCTLR2_EL2

When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL2 using the accessor name SCTLR2_EL2 or SCTLR2_EL1 are not guaranteed to be ordered with respect to accesses using the other accessor name.

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

MRS <Xt>, SCTLR2_EL2

op0	op1	CRn	CRm	op2
0b11	0b100	0b0001	0b0000	0b011

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.SCTLR2En == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.SCTLR2En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else X[t, 64] = SCTLR2_EL2; elsif PSTATE.EL == EL3 then X[t, 64] = SCTLR2_EL2;

MSR SCTLR2_EL2, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b100	0b0001	0b0000	0b011

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.SCTLR2En == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.SCTLR2En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else SCTLR2_EL2 = X[t, 64]; elsif PSTATE.EL == EL3 then SCTLR2_EL2 = X[t, 64];

MRS <Xt>, SCTLR2_EL1

op0	op1	CRn	CRm	op2
0b11	0b000	0b0001	0b0000	0b011

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.SCTLR2En == '0' then UNDEFINED; elsif EL2Enabled() && HCR_EL2.TRVM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.SCTLR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && (!IsHCRXEL2Enabled() || HCRX_EL2.SCTLR2En == '0') then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3.SCTLR2En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then X[t, 64] = NVMem[0x278]; else X[t, 64] = SCTLR2_EL1; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.SCTLR2En == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.SCTLR2En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif ELIsInHost(EL2) then X[t, 64] = SCTLR2_EL2; else X[t, 64] = SCTLR2_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = SCTLR2_EL1;

MSR SCTLR2_EL1, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b000	0b0001	0b0000	0b011

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.SCTLR2En == '0' then UNDEFINED; elsif EL2Enabled() && HCR_EL2.TVM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.SCTLR_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && (!IsHCRXEL2Enabled() || HCRX_EL2.SCTLR2En == '0') then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3.SCTLR2En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then NVMem[0x278] = X[t, 64]; else SCTLR2_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.SCTLR2En == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.SCTLR2En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif ELIsInHost(EL2) then SCTLR2_EL2 = X[t, 64]; else SCTLR2_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then SCTLR2_EL1 = X[t, 64];

63	62	61	60	59	58	57	56	55	54	53	52	51	50	49	48	47	46	45	44	43	42	41	40	39	38	37	36	35	34	33	32
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
RES0
RES0																			CPTM0	CPTM	CPTA0	CPTA	EnPACM0	EnPACM	EnIDCP128	EASE	EnANERR	EnADERR	NMEA	EMEC	RES0

SCTLR2_EL2, System Control Register (EL2)

Purpose

Configuration

Attributes

Field descriptions

Bits [63:13]

CPTM0, bit [12]
When FEAT_CPA2 is implemented and the Effective value of HCR_EL2.E2H is 1:

Otherwise:

CPTM, bit [11]
When FEAT_CPA2 is implemented:

Otherwise:

CPTA0, bit [10]
When FEAT_CPA2 is implemented and the Effective value of HCR_EL2.E2H is 1:

Otherwise:

CPTA, bit [9]
When FEAT_CPA2 is implemented:

Otherwise:

EnPACM0, bit [8]
When FEAT_PAuth_LR is implemented and the Effective value of HCR_EL2.E2H is 1:

Otherwise:

EnPACM, bit [7]
When FEAT_PAuth_LR is implemented:

Otherwise:

EnIDCP128, bit [6]
When FEAT_SYSREG128 is implemented:

Otherwise:

EASE, bit [5]
When FEAT_DoubleFault2 is implemented:

Otherwise:

EnANERR, bit [4]
When FEAT_ANERR is implemented:

Otherwise:

EnADERR, bit [3]
When FEAT_ADERR is implemented:

Otherwise:

NMEA, bit [2]
When FEAT_DoubleFault2 is implemented:

Otherwise:

EMEC, bit [1]
When FEAT_MEC is implemented:

Otherwise:

Bit [0]

Accessing SCTLR2_EL2

MRS <Xt>, SCTLR2_EL2

MSR SCTLR2_EL2, <Xt>

MRS <Xt>, SCTLR2_EL1

MSR SCTLR2_EL1, <Xt>

SCTLR2_EL2, System Control Register (EL2)

Purpose

Configuration

Attributes

Field descriptions

Bits [63:13]

CPTM0, bit [12]When FEAT_CPA2 is implemented and the Effective value of HCR_EL2.E2H is 1:

Otherwise:

CPTM, bit [11]When FEAT_CPA2 is implemented:

Otherwise:

CPTA0, bit [10]When FEAT_CPA2 is implemented and the Effective value of HCR_EL2.E2H is 1:

Otherwise:

CPTA, bit [9]When FEAT_CPA2 is implemented:

Otherwise:

EnPACM0, bit [8]When FEAT_PAuth_LR is implemented and the Effective value of HCR_EL2.E2H is 1:

Otherwise:

EnPACM, bit [7]When FEAT_PAuth_LR is implemented:

Otherwise:

EnIDCP128, bit [6]When FEAT_SYSREG128 is implemented:

Otherwise:

EASE, bit [5]When FEAT_DoubleFault2 is implemented:

Otherwise:

EnANERR, bit [4]When FEAT_ANERR is implemented:

Otherwise:

EnADERR, bit [3]When FEAT_ADERR is implemented:

Otherwise:

NMEA, bit [2]When FEAT_DoubleFault2 is implemented:

Otherwise:

EMEC, bit [1]When FEAT_MEC is implemented:

Otherwise:

Bit [0]

Accessing SCTLR2_EL2

MRS <Xt>, SCTLR2_EL2

MSR SCTLR2_EL2, <Xt>

MRS <Xt>, SCTLR2_EL1

MSR SCTLR2_EL1, <Xt>

CPTM0, bit [12]
When FEAT_CPA2 is implemented and the Effective value of HCR_EL2.E2H is 1:

CPTM, bit [11]
When FEAT_CPA2 is implemented:

CPTA0, bit [10]
When FEAT_CPA2 is implemented and the Effective value of HCR_EL2.E2H is 1:

CPTA, bit [9]
When FEAT_CPA2 is implemented:

EnPACM0, bit [8]
When FEAT_PAuth_LR is implemented and the Effective value of HCR_EL2.E2H is 1:

EnPACM, bit [7]
When FEAT_PAuth_LR is implemented:

EnIDCP128, bit [6]
When FEAT_SYSREG128 is implemented:

EASE, bit [5]
When FEAT_DoubleFault2 is implemented:

EnANERR, bit [4]
When FEAT_ANERR is implemented:

EnADERR, bit [3]
When FEAT_ADERR is implemented:

NMEA, bit [2]
When FEAT_DoubleFault2 is implemented:

EMEC, bit [1]
When FEAT_MEC is implemented: