HCPTR

AArch32 System register HCPTR bits [31:0] are architecturally mapped to AArch64 System register CPTR_EL2[31:0].

This register is present only when EL2 is capable of using AArch32. Otherwise, direct accesses to HCPTR are UNDEFINED.

Attributes

Field descriptions

TCPAC, bit [31]

Traps Non-secure EL1 accesses to the CPACR to Hyp mode.

TCPAC	Meaning
0b0	This control does not cause any instructions to be trapped.
0b1	Non-secure EL1 accesses to the CPACR are trapped to Hyp mode.

Note

The CPACR is not accessible at EL0.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL3 or the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

TAM, bit [30]
When FEAT_AMUv1 is implemented:

Trap Activity Monitor access. Traps Non-secure EL1 and EL0 accesses to all Activity Monitor registers to EL2.

TAM	Meaning
0b0	Accesses from Non-secure EL1 and EL0 to Activity Monitor registers are not trapped.
0b1	Accesses from Non-secure EL1 and EL0 to Activity Monitor registers are trapped to Hyp mode.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL3 or the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Otherwise:

Bits [29:21]

TTA, bit [20]

Traps Non-secure System register accesses to all implemented trace registers to Hyp mode.

TTA

Meaning

0b0

This control does not cause any instructions to be trapped.

0b1

Any Non-secure System register access to an implemented trace register is trapped to Hyp mode, unless the access is trapped to EL1 by a CPACR or NSACR control, or the access is from Non-secure EL0 and the definition of the register in the appropriate trace architecture specification indicates that the register is not accessible from EL0. A trapped instruction generates:

A Hyp Trap exception, if the exception is taken from Non-secure EL0 or EL1.
An Undefined Instruction exception taken to Hyp mode, if the exception is taken from Hyp mode.

If the implementation does not include a trace unit, or does not include a System register interface to the trace unit registers, it is IMPLEMENTATION DEFINED whether this bit:

Is RES0.
Is RES1.
Can be written from Hyp mode, and from Secure Monitor mode when SCR.NS is 1.

If EL3 is implemented and is using AArch32, and the value of NSACR.NSTRCDIS is 1, in Non-secure state this field behaves as RAO/WI, regardless of its actual value.

Note

The ETMv4 architecture and ETE do not permit EL0 to access the trace registers. If the trace unit implements FEAT_ETMv4 or FEAT_ETE, EL0 accesses to the trace registers are UNDEFINED, and a resulting Undefined Instruction exception is higher priority than a HCPTR.TTA Hyp Trap exception.
The Arm architecture does not provide traps on trace register accesses through the optional memory-mapped debug interface.

System register accesses to the trace registers can have side-effects. When a System register access is trapped, any side-effects that are normally associated with the access do not occur before the exception is taken.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL3 or the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Bits [19:16]

TASE, bit [15]

Traps Non-secure execution of Advanced SIMD instructions to Hyp mode when the value of HCPTR.TCP10 is 0.

TASE

Meaning

0b0

This control does not cause any instructions to be trapped.

0b1

When the value of HCPTR.TCP10 is 0, any attempt to execute an Advanced SIMD instruction in Non-secure state is trapped to Hyp mode, unless it is trapped to EL1 by a CPACR or NSACR control. A trapped instruction generates:

A Hyp Trap exception, if the exception is taken from Non-secure EL0 or EL1.
An Undefined Instruction exception taken to Hyp mode, if the exception is taken from Hyp mode.

When the value of HCPTR.TCP10 is 1, the value of this field is ignored.

If the implementation does not include Advanced SIMD and floating-point functionality, this field is RES1. Otherwise, it is IMPLEMENTATION DEFINED whether this field is implemented as a RW field. If it is not implemented as a RW field, then it is RAZ/WI.

If EL3 is implemented and is using AArch32, and the value of NSACR.NSASEDIS is 1, in Non-secure state this field behaves as RAO/WI, regardless of its actual value. This applies even if the field is implemented as RAZ/WI.

For the list of instructions affected by this field, see 'Controls of Advanced SIMD operation that do not apply to floating-point operation'.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL3 or the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Bit [14]

Bits [13:12]

TCP11, bit [11]
When FEAT_FP is implemented and FEAT_AdvSIMD is implemented:

The value of this field is ignored. If this field is programmed with a different value to the TCP10 bit then this field is UNKNOWN on a direct read of the HCPTR.

If the implementation does not include Advanced SIMD and floating-point functionality, this field is RES1.

If EL3 is implemented and is using AArch32, and the value of NSACR.cp10 is 0, in Non-secure state this field behaves as RAO/WI, regardless of its actual value.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL3 or the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Accessing this field has the following behavior:

Access is RAO/WI if all of the following are true:
- EL3 is implemented
- EL3 is using AArch32
- !IsCurrentSecurityState(SS_Secure)
- NSACR.cp10 == 0

Otherwise:

TCP10, bit [10]
When FEAT_FP is implemented and FEAT_AdvSIMD is implemented:

Trap Non-secure accesses to Advanced SIMD and floating-point functionality to Hyp mode:

TCP10

Meaning

0b0

This control does not cause any instructions to be trapped.

0b1

Any attempted access to Advanced SIMD and floating-point functionality from Non-secure state is trapped to Hyp mode, unless it is trapped to EL1 by a CPACR or NSACR control. A trapped instruction generates:

A Hyp Trap exception, if the exception is taken from Non-secure EL0 or EL1.
An Undefined Instruction exception taken to Hyp mode, if the exception is taken from Hyp mode.

The Advanced SIMD and floating-point features controlled by these fields are:

Execution of any floating-point or Advanced SIMD instruction.
Any access to the Advanced SIMD and floating-point registers D0-D31 and their views as S0-S31 and Q0-Q15.
Any access to the FPSCR, FPSID, MVFR0, MVFR1, MVFR2, or FPEXC System registers.

If the implementation does not include Advanced SIMD and floating-point functionality, this field is RES1.

If EL3 is implemented and is using AArch32, and the value of NSACR.cp10 is 0, in Non-secure state this field behaves as RAO/WI, regardless of its actual value.

The reset behavior of this field is:

On a Warm reset:
- When the highest implemented Exception level is EL3 or the highest implemented Exception level is EL2, this field resets to 0.
- Otherwise, this field resets to an architecturally UNKNOWN value.

Accessing this field has the following behavior:

Access is RAO/WI if all of the following are true:
- EL3 is implemented
- EL3 is using AArch32
- !IsCurrentSecurityState(SS_Secure)
- NSACR.cp10 == 0

Otherwise:

Bits [9:0]

Accessing HCPTR

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

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coproc	opc1	CRn	CRm	opc2
0b1111	0b100	0b0001	0b0001	0b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T1 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T1 == '1' then AArch32.TakeHypTrapException(0x03); else UNDEFINED; elsif PSTATE.EL == EL2 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then UNDEFINED; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.AArch32SystemAccessTrap(EL3, 0x03); else R[t] = HCPTR; elsif PSTATE.EL == EL3 then if SCR.NS == '0' then UNDEFINED; else R[t] = HCPTR;

MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coproc	opc1	CRn	CRm	opc2
0b1111	0b100	0b0001	0b0001	0b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T1 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T1 == '1' then AArch32.TakeHypTrapException(0x03); else UNDEFINED; elsif PSTATE.EL == EL2 then if Halted() && HaveEL(EL3) && EDSCR.SDD == '1' && boolean IMPLEMENTATION_DEFINED "EL3 trap priority when SDD == '1'" && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then UNDEFINED; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.TCPAC == '1' then if Halted() && EDSCR.SDD == '1' then UNDEFINED; else AArch64.AArch32SystemAccessTrap(EL3, 0x03); else HCPTR = R[t]; elsif PSTATE.EL == EL3 then if SCR.NS == '0' then UNDEFINED; else HCPTR = R[t];

HCPTR, Hyp Architectural Feature Trap Register

Purpose

Configuration

Attributes

Field descriptions

TCPAC, bit [31]

TAM, bit [30]
When FEAT_AMUv1 is implemented:

Otherwise:

Bits [29:21]

TTA, bit [20]

Bits [19:16]

TASE, bit [15]

Bit [14]

Bits [13:12]

TCP11, bit [11]
When FEAT_FP is implemented and FEAT_AdvSIMD is implemented:

Otherwise:

TCP10, bit [10]
When FEAT_FP is implemented and FEAT_AdvSIMD is implemented:

Otherwise:

Bits [9:0]

Accessing HCPTR

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

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
TCPAC	TAM	RES0									TTA	RES0				TASE	RES0	RES1		TCP11	TCP10	RES1

HCPTR, Hyp Architectural Feature Trap Register

Purpose

Configuration

Attributes

Field descriptions

TCPAC, bit [31]

TAM, bit [30]When FEAT_AMUv1 is implemented:

Otherwise:

Bits [29:21]

TTA, bit [20]

Bits [19:16]

TASE, bit [15]

Bit [14]

Bits [13:12]

TCP11, bit [11]When FEAT_FP is implemented and FEAT_AdvSIMD is implemented:

Otherwise:

TCP10, bit [10]When FEAT_FP is implemented and FEAT_AdvSIMD is implemented:

Otherwise:

Bits [9:0]

Accessing HCPTR

MRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

TAM, bit [30]
When FEAT_AMUv1 is implemented:

TCP11, bit [11]
When FEAT_FP is implemented and FEAT_AdvSIMD is implemented:

TCP10, bit [10]
When FEAT_FP is implemented and FEAT_AdvSIMD is implemented: