Auxiliary Control Register (EL1)
Provides IMPLEMENTATION DEFINED configuration and control options for execution at EL1 and EL0.
Arm recommends the contents of this register have no effect on the PE when the Effective value of HCR_EL2.{E2H, TGE} is {1, 1}, and instead the configuration and control fields are provided by the ACTLR_EL2 register. This avoids the need for software to manage the contents of these register when switching between a Guest OS and a Host OS.
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.
ACTLR_EL1 is a 64-bit register.
| 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 | |||||||||||||||||||||||||||||||
IMPLEMENTATION DEFINED.
The reset behavior of this field is:
If the IMPLEMENTATION DEFINED ACTLR_EL12 accessor is implemented, the following behaviors are also implemented:
Accesses to this register use the following encodings in the System register encoding space:
MRS <Xt>, ACTLR_EL1
(op0 = 0b11, op1 = 0b000, CRn = 0b0001, CRm = 0b0000, op2 = 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'} && (!boolean IMPLEMENTATION_DEFINED "IMPLEMENTED_ACTLR_ELx accessor behavior" || EffectiveHCR_EL2_NVx() == '111') then X[t, 64] = NVMem[0x118]; else X[t, 64] = ACTLR_EL1; elsif PSTATE.EL == EL2 then if boolean IMPLEMENTATION_DEFINED "IMPLEMENTED_ACTLR_ELx accessor behavior" && ELIsInHost(EL2) then X[t, 64] = ACTLR_EL2; else X[t, 64] = ACTLR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = ACTLR_EL1;
MSR ACTLR_EL1, <Xt>
(op0 = 0b11, op1 = 0b000, CRn = 0b0001, CRm = 0b0000, op2 = 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'} && (!boolean IMPLEMENTATION_DEFINED "IMPLEMENTED_ACTLR_ELx accessor behavior" || EffectiveHCR_EL2_NVx() == '111') then NVMem[0x118] = X[t, 64]; else if IsFeatureImplemented(FEAT_SRMASK) then ACTLR_EL1 = (X[t, 64] AND NOT EffectiveACTLRMASK_EL1()) OR (ACTLR_EL1 AND EffectiveACTLRMASK_EL1()); else ACTLR_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then if boolean IMPLEMENTATION_DEFINED "IMPLEMENTED_ACTLR_ELx accessor behavior" && ELIsInHost(EL2) then if IsFeatureImplemented(FEAT_SRMASK) then ACTLR_EL2 = (X[t, 64] AND NOT EffectiveACTLRMASK_EL2()) OR (ACTLR_EL2 AND EffectiveACTLRMASK_EL2()); else ACTLR_EL2 = X[t, 64]; else ACTLR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then ACTLR_EL1 = X[t, 64];
MRS <Xt>, ACTLR_EL12
(op0 = 0b11, op1 = 0b101, CRn = 0b0001, CRm = 0b0000, op2 = 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[t, 64] = NVMem[0x118]; elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then X[t, 64] = ACTLR_EL1; else UNDEFINED; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then X[t, 64] = ACTLR_EL1; else UNDEFINED;
MSR ACTLR_EL12, <Xt>
(op0 = 0b11, op1 = 0b101, CRn = 0b0001, CRm = 0b0000, op2 = 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[t, 64]; elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x18); else UNDEFINED; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then ACTLR_EL1 = X[t, 64]; else UNDEFINED; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then ACTLR_EL1 = X[t, 64]; else UNDEFINED;
MRS <Xt>, ACTLRALIAS_EL1
(op0 = 0b11, op1 = 0b000, CRn = 0b0001, CRm = 0b0100, op2 = 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'} && (!boolean IMPLEMENTATION_DEFINED "IMPLEMENTED_ACTLR_ELx accessor behavior" || EffectiveHCR_EL2_NVx() == '111') then X[t, 64] = NVMem[0x118]; else X[t, 64] = ACTLR_EL1; elsif PSTATE.EL == EL2 then if boolean IMPLEMENTATION_DEFINED "IMPLEMENTED_ACTLR_ELx accessor behavior" && ELIsInHost(EL2) then X[t, 64] = ACTLR_EL2; else X[t, 64] = ACTLR_EL1; elsif PSTATE.EL == EL3 then X[t, 64] = ACTLR_EL1;
MSR ACTLRALIAS_EL1, <Xt>
(op0 = 0b11, op1 = 0b000, CRn = 0b0001, CRm = 0b0100, op2 = 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'} && (!boolean IMPLEMENTATION_DEFINED "IMPLEMENTED_ACTLR_ELx accessor behavior" || EffectiveHCR_EL2_NVx() == '111') then NVMem[0x118] = X[t, 64]; else if IsFeatureImplemented(FEAT_SRMASK) then ACTLR_EL1 = (X[t, 64] AND NOT EffectiveACTLRMASK_EL1()) OR (ACTLR_EL1 AND EffectiveACTLRMASK_EL1()); else ACTLR_EL1 = X[t, 64]; elsif PSTATE.EL == EL2 then if boolean IMPLEMENTATION_DEFINED "IMPLEMENTED_ACTLR_ELx accessor behavior" && ELIsInHost(EL2) then if IsFeatureImplemented(FEAT_SRMASK) then ACTLR_EL2 = (X[t, 64] AND NOT EffectiveACTLRMASK_EL2()) OR (ACTLR_EL2 AND EffectiveACTLRMASK_EL2()); else X[t, 64] = ACTLR_EL2; else ACTLR_EL1 = X[t, 64]; elsif PSTATE.EL == EL3 then ACTLR_EL1 = X[t, 64];
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