The TTBR0_EL2 characteristics are:
When the Effective value of HCR_EL2.E2H is not 1, holds the base address of the translation table for the initial lookup for stage 1 of an address translation in the EL2 translation regime, and other information for this translation regime.
When the Effective value of HCR_EL2.E2H is 1, holds the base address of the translation table for the initial lookup for stage 1 of the translation of an address from the lower VA range in the EL2&0 translation regime, and other information for this translation regime.
AArch64 System register TTBR0_EL2 bits [47:1] are architecturally mapped to AArch32 System register HTTBR[47:1].
If EL2 is not implemented, this register is RES0 from EL3.
This register has no effect if EL2 is not enabled in the current Security state.
TTBR0_EL2 is a 128-bit register that can also be accessed as a 64-bit value. If it is accessed as a 64-bit register, accesses read and write bits [63:0] and do not modify bits [127:64].
TTBR0_EL2 is a:
| 127 | 126 | 125 | 124 | 123 | 122 | 121 | 120 | 119 | 118 | 117 | 116 | 115 | 114 | 113 | 112 | 111 | 110 | 109 | 108 | 107 | 106 | 105 | 104 | 103 | 102 | 101 | 100 | 99 | 98 | 97 | 96 |
| RES0 | |||||||||||||||||||||||||||||||
| 95 | 94 | 93 | 92 | 91 | 90 | 89 | 88 | 87 | 86 | 85 | 84 | 83 | 82 | 81 | 80 | 79 | 78 | 77 | 76 | 75 | 74 | 73 | 72 | 71 | 70 | 69 | 68 | 67 | 66 | 65 | 64 |
| RES0 | BADDR[55:5][50:43] | RES0 | |||||||||||||||||||||||||||||
| 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 |
| ASID | BADDR[55:5][42:0] | ||||||||||||||||||||||||||||||
| 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 |
| BADDR[55:5][42:0] | RES0 | SKL | CnP | ||||||||||||||||||||||||||||
Reserved, RES0.
Translation table base address:
Address bit x is the minimum address bit required to align the translation table to the size of the table. x is calculated based on LOG2(StartTableSize), as described in VMSAv9-128. The smallest permitted value of x is 5.
The BADDR[55:5] field is split as follows:
The reset behavior of this field is:
Reserved, RES0.
When the Effective value of HCR_EL2.E2H is 1, it holds an ASID for the translation table base address. The TCR_EL2.A1 field selects either TTBR0_EL2.ASID or TTBR1_EL2.ASID.
If the implementation has only 8 bits of ASID, then the upper 8 bits of this field are RES0.
The reset behavior of this field is:
Reserved, RES0.
Reserved, RES0.
Skip Level associated with translation table walks using TTBR0_EL2.
This determines the number of levels to be skipped from the regular start level of the stage 1 EL2&0 translation table walks using TTBR0_EL2.
| SKL | Meaning |
|---|---|
| 0b00 |
Skip 0 level from the regular start level. |
| 0b01 |
Skip 1 level from the regular start level. |
| 0b10 |
Skip 2 levels from the regular start level. |
| 0b11 |
Skip 3 levels from the regular start level. |
The reset behavior of this field is:
Common not Private. This bit indicates whether each entry that is pointed to by TTBR0_EL2 is a member of a common set that can be used by every PE in the Inner Shareable domain for which the value of TTBR0_EL2.CnP is 1.
| CnP | Meaning |
|---|---|
| 0b0 | The translation table entries pointed to by TTBR0_EL2 for the current translation regime, and ASID if applicable, are permitted to differ from corresponding entries for TTBR0_EL2 for other PEs in the Inner Shareable domain. This is not affected by:
|
| 0b1 | The translation table entries pointed to by TTBR0_EL2 are the same as the translation table entries for every other PE in the Inner Shareable domain for which the value of TTBR0_EL2.CnP is 1 and all of the following apply:
|
This bit is permitted to be cached in a TLB.
If the value of the TTBR0_EL2.CnP bit is 1 on multiple PEs in the same Inner Shareable domain and those TTBR0_EL2s do not point to the same translation table entries when the other conditions specified for the case when the value of CnP is 1 apply, then the results of translations are CONSTRAINED UNPREDICTABLE, see 'CONSTRAINED UNPREDICTABLE behaviors due to caching of control or data values'.
The reset behavior of this field is:
Reserved, RES0.
| 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 |
| ASID | BADDR[47:1] | ||||||||||||||||||||||||||||||
| BADDR[47:1] | CnP | ||||||||||||||||||||||||||||||
When the Effective value of HCR_EL2.E2H is not 1, this field is RES0.
When the Effective value of HCR_EL2.E2H is 1, it holds an ASID for the translation table base address. The TCR_EL2.A1 field selects either TTBR0_EL2.ASID or TTBR1_EL2.ASID.
If the implementation has only 8 bits of ASID, then the upper 8 bits of this field are RES0.
The reset behavior of this field is:
Reserved, RES0.
Translation table base address:
Address bit x is the minimum address bit required to align the translation table to the size of the table. The AArch64 Virtual Memory System Architecture chapter describes how x is calculated based on the value of TCR_EL2.T0SZ, the translation stage, and the translation granule size.
If the value of TCR_EL2.{I}PS is not 0b110, then:
The BADDR field represents a 52-bit address if one of the following applies:
When TTBR0_EL2.BADDR represents a 52-bit addresses, all of the following apply:
If BADDR represents a 52-bit address, and the translation table has fewer than eight entries, the table must be aligned to 64 bytes. Otherwise the translation table must be aligned to the size of the table.
The OA size specified by TCR_EL2.{I}PS is determined as follows:
For the 64KB granule, if FEAT_LPA is not implemented, and the value of TCR_EL2.{I}PS is 0b110, one the following IMPLEMENTATION DEFINED behaviors occur:
When the value of ID_AA64MMFR0_EL1.PARange indicates that the implementation supports a 56 bit PA size, bits A[55:52] of the stage 1 translation table base address are zero.
If any register bit[47:1] that is defined as RES0 has the value 1 when a translation table walk is done using TTBR0_EL2, then the translation table base address might be misaligned, with effects that are CONSTRAINED UNPREDICTABLE, and must be one of the following:
The reset behavior of this field is:
Common not Private. This bit indicates whether each entry that is pointed to by TTBR0_EL2 is a member of a common set that can be used by every PE in the Inner Shareable domain for which the value of TTBR0_EL2.CnP is 1.
| CnP | Meaning |
|---|---|
| 0b0 | The translation table entries pointed to by TTBR0_EL2 for the current translation regime, and ASID if applicable, are permitted to differ from corresponding entries for TTBR0_EL2 for other PEs in the Inner Shareable domain. This is not affected by:
|
| 0b1 | The translation table entries pointed to by TTBR0_EL2 are the same as the translation table entries for every other PE in the Inner Shareable domain for which the value of TTBR0_EL2.CnP is 1 and all of the following apply:
|
This bit is permitted to be cached in a TLB.
If the value of the TTBR0_EL2.CnP bit is 1 on multiple PEs in the same Inner Shareable domain and those TTBR0_EL2s do not point to the same translation table entries when the other conditions specified for the case when the value of CnP is 1 apply, then the results of translations are CONSTRAINED UNPREDICTABLE, see 'CONSTRAINED UNPREDICTABLE behaviors due to caching of control or data values'.
The reset behavior of this field is:
Reserved, RES0.
When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL2 using the accessor name TTBR0_EL2 or TTBR0_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:
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b100 | 0b0010 | 0b0000 | 0b000 |
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 X[t, 64] = TTBR0_EL2<63:0>; elsif PSTATE.EL == EL3 then X[t, 64] = TTBR0_EL2<63:0>;
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b100 | 0b0010 | 0b0000 | 0b000 |
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 TTBR0_EL2<63:0> = X[t, 64]; elsif PSTATE.EL == EL3 then TTBR0_EL2<63:0> = X[t, 64];
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b000 | 0b0010 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.TRVM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.TTBR0_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then X[t, 64] = NVMem[0x200]; else X[t, 64] = TTBR0_EL1<63:0>; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then X[t, 64] = TTBR0_EL2<63:0>; else X[t, 64] = TTBR0_EL1<63:0>; elsif PSTATE.EL == EL3 then X[t, 64] = TTBR0_EL1<63:0>;
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b000 | 0b0010 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.TVM == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.TTBR0_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EffectiveHCR_EL2_NVx() IN {'111'} then NVMem[0x200] = X[t, 64]; else TTBR0_EL1<63:0> = X[t, 64]; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then TTBR0_EL2<63:0> = X[t, 64]; else TTBR0_EL1<63:0> = X[t, 64]; elsif PSTATE.EL == EL3 then TTBR0_EL1<63:0> = X[t, 64];
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b100 | 0b0010 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x14); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.D128En == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.D128En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x14); else (X[t2, 64], X[t, 64]) = Split(TTBR0_EL2, 64); elsif PSTATE.EL == EL3 then (X[t2, 64], X[t, 64]) = Split(TTBR0_EL2, 64);
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b100 | 0b0010 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64.SystemAccessTrap(EL2, 0x14); else UNDEFINED; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.D128En == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.D128En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x14); else TTBR0_EL2<127:0> = X[t2, 64]:X[t, 64]; elsif PSTATE.EL == EL3 then TTBR0_EL2<127:0> = X[t2, 64]:X[t, 64];
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b000 | 0b0010 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.D128En == '0' then UNDEFINED; elsif EL2Enabled() && HCR_EL2.TRVM == '1' then AArch64.SystemAccessTrap(EL2, 0x14); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGRTR_EL2.TTBR0_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x14); elsif EL2Enabled() && (!IsHCRXEL2Enabled() || HCRX_EL2.D128En == '0') then AArch64.SystemAccessTrap(EL2, 0x14); elsif HaveEL(EL3) && SCR_EL3.D128En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x14); elsif EffectiveHCR_EL2_NVx() IN {'111'} then (X[t2, 64], X[t, 64]) = Split(NVMem[0x200, 128], 64); else (X[t2, 64], X[t, 64]) = Split(TTBR0_EL1, 64); elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.D128En == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.D128En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x14); elsif ELIsInHost(EL2) then (X[t2, 64], X[t, 64]) = Split(TTBR0_EL2, 64); else (X[t2, 64], X[t, 64]) = Split(TTBR0_EL1, 64); elsif PSTATE.EL == EL3 then (X[t2, 64], X[t, 64]) = Split(TTBR0_EL1, 64);
| op0 | op1 | CRn | CRm | op2 |
|---|---|---|---|---|
| 0b11 | 0b000 | 0b0010 | 0b0000 | 0b000 |
if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.D128En == '0' then UNDEFINED; elsif EL2Enabled() && HCR_EL2.TVM == '1' then AArch64.SystemAccessTrap(EL2, 0x14); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGWTR_EL2.TTBR0_EL1 == '1' then AArch64.SystemAccessTrap(EL2, 0x14); elsif EL2Enabled() && (!IsHCRXEL2Enabled() || HCRX_EL2.D128En == '0') then AArch64.SystemAccessTrap(EL2, 0x14); elsif HaveEL(EL3) && SCR_EL3.D128En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x14); elsif EffectiveHCR_EL2_NVx() IN {'111'} then NVMem[0x200, 128] = X[t2, 64]:X[t, 64]; else TTBR0_EL1<127:0> = X[t2, 64]:X[t, 64]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3.D128En == '0' then UNDEFINED; elsif HaveEL(EL3) && SCR_EL3.D128En == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x14); elsif ELIsInHost(EL2) then TTBR0_EL2<127:0> = X[t2, 64]:X[t, 64]; else TTBR0_EL1<127:0> = X[t2, 64]:X[t, 64]; elsif PSTATE.EL == EL3 then TTBR0_EL1<127:0> = X[t2, 64]:X[t, 64];
26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6
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