ACTLR_EL1

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ACTLR_EL1, Auxiliary Control Register (EL1)

Purpose

Provides IMPLEMENTATION DEFINED configuration and control options for execution at EL1 and EL0.

Configuration

AArch64 System register ACTLR_EL1 bits [31:0] are architecturally mapped to AArch32 System register ACTLR[31:0].

AArch64 System register ACTLR_EL1 bits [63:32] are architecturally mapped to AArch32 System register ACTLR2[31:0].

This register is present only when FEAT_AA64 is implemented. Otherwise, direct accesses to ACTLR_EL1 are UNDEFINED.

Attributes

Field descriptions

IMPLEMENTATION DEFINED, bits [63:0]

Accessing ACTLR_EL1

If the IMPLEMENTATION DEFINED ACTLR_EL12 accessor is implemented, the following behaviors are also implemented:

MRS/MSR to ACTLR_EL1 from EL2 when the Effective value of HCR_EL2.E2H is 1 accesses ACTLR_EL2.
MRS/MSR to ACTLR_EL1 from EL1 when the Effective value of HCR_EL2.{NV2, NV1, NV} is {1,0,1} accesses ACTLR_EL1 directly and is not transformed to a memory access.
MRS/MSR to ACTLRALIAS_EL1 behaves in the same way as ACTLR_EL1.

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

MRS <Xt>, ACTLR_EL1

op0	op1	CRn	CRm	op2
0b11	0b000	0b0001	0b0000	0b001

if !IsFeatureImplemented(FEAT_AA64) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2().TACR == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'1x1'} && (!ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") || EffectiveHCR_EL2_NVx() == '111') then X{64}(t) = NVMem(0x118); else X{64}(t) = ACTLR_EL1(); end; elsif PSTATE.EL == EL2 then if ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") && ELIsInHost(EL2) then X{64}(t) = ACTLR_EL2(); else X{64}(t) = ACTLR_EL1(); end; elsif PSTATE.EL == EL3 then X{64}(t) = ACTLR_EL1(); end;

MSR ACTLR_EL1, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b000	0b0001	0b0000	0b001

if !IsFeatureImplemented(FEAT_AA64) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2().TACR == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'1x1'} && (!ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") || EffectiveHCR_EL2_NVx() == '111') then NVMem(0x118) = X{64}(t); else if IsFeatureImplemented(FEAT_SRMASK) then ACTLR_EL1() = (X{64}(t) AND NOT EffectiveACTLRMASK_EL1()) OR (ACTLR_EL1() AND EffectiveACTLRMASK_EL1()); else ACTLR_EL1() = X{64}(t); end; end; elsif PSTATE.EL == EL2 then if ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") && ELIsInHost(EL2) then if IsFeatureImplemented(FEAT_SRMASK) then ACTLR_EL2() = (X{64}(t) AND NOT EffectiveACTLRMASK_EL2()) OR (ACTLR_EL2() AND EffectiveACTLRMASK_EL2()); else ACTLR_EL2() = X{64}(t); end; else ACTLR_EL1() = X{64}(t); end; elsif PSTATE.EL == EL3 then ACTLR_EL1() = X{64}(t); end;

When an implementation implements ACTLR_ELx accessor behavior and FEAT_VHE is implemented

MRS <Xt>, ACTLR_EL12

op0	op1	CRn	CRm	op2
0b11	0b101	0b0001	0b0000	0b001

if !IsFeatureImplemented(FEAT_AA64) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() == '101' then X{64}(t) = NVMem(0x118); elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then X{64}(t) = ACTLR_EL1(); else Undefined(); end; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then X{64}(t) = ACTLR_EL1(); else Undefined(); end; end;

When an implementation implements ACTLR_ELx accessor behavior and FEAT_VHE is implemented

MSR ACTLR_EL12, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b101	0b0001	0b0000	0b001

if !IsFeatureImplemented(FEAT_AA64) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() == '101' then NVMem(0x118) = X{64}(t); elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then ACTLR_EL1() = X{64}(t); else Undefined(); end; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then ACTLR_EL1() = X{64}(t); else Undefined(); end; end;

When FEAT_SRMASK is implemented

MRS <Xt>, ACTLRALIAS_EL1

op0	op1	CRn	CRm	op2
0b11	0b000	0b0001	0b0100	0b101

if !IsFeatureImplemented(FEAT_AA64) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2().TACR == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3().FGTEn2 == '0') || HFGRTR2_EL2().nACTLRALIAS_EL1 == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'1x1'} && (!ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") || EffectiveHCR_EL2_NVx() == '111') then X{64}(t) = NVMem(0x118); else X{64}(t) = ACTLR_EL1(); end; elsif PSTATE.EL == EL2 then if ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") && ELIsInHost(EL2) then X{64}(t) = ACTLR_EL2(); else X{64}(t) = ACTLR_EL1(); end; elsif PSTATE.EL == EL3 then X{64}(t) = ACTLR_EL1(); end;

When FEAT_SRMASK is implemented

MSR ACTLRALIAS_EL1, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b000	0b0001	0b0100	0b101

if !IsFeatureImplemented(FEAT_AA64) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2().TACR == '1' then AArch64_SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT2) && ((HaveEL(EL3) && SCR_EL3().FGTEn2 == '0') || HFGWTR2_EL2().nACTLRALIAS_EL1 == '0') then AArch64_SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'1x1'} && (!ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") || EffectiveHCR_EL2_NVx() == '111') then NVMem(0x118) = X{64}(t); else if IsFeatureImplemented(FEAT_SRMASK) then ACTLR_EL1() = (X{64}(t) AND NOT EffectiveACTLRMASK_EL1()) OR (ACTLR_EL1() AND EffectiveACTLRMASK_EL1()); else ACTLR_EL1() = X{64}(t); end; end; elsif PSTATE.EL == EL2 then if ImpDefBool("IMPLEMENTED_ACTLR_ELx accessor behavior") && ELIsInHost(EL2) then if IsFeatureImplemented(FEAT_SRMASK) then ACTLR_EL2() = (X{64}(t) AND NOT EffectiveACTLRMASK_EL2()) OR (ACTLR_EL2() AND EffectiveACTLRMASK_EL2()); else ACTLR_EL2() = X{64}(t); end; else ACTLR_EL1() = X{64}(t); end; elsif PSTATE.EL == EL3 then ACTLR_EL1() = X{64}(t); end;

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
IMPLEMENTATION DEFINED
IMPLEMENTATION DEFINED