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DISR: Deferred Interrupt Status Register

Purpose

Records that an SError exception has been consumed by an ESB instruction.

Configuration

AArch32 System register DISR bits [31:0] are architecturally mapped to AArch64 System register DISR_EL1[31:0].

This register is present only when FEAT_RAS is implemented. Otherwise, direct accesses to DISR are UNDEFINED.

Attributes

DISR is a 32-bit register.

Field descriptions

When the ESB instruction is executed at EL2:

313029282726252423222120191817161514131211109876543210
ARES0AETEARES0DFSC

A, bit [31]

Set to 1 when an ESB instruction defers an asynchronous SError exception. If the implementation does not include any sources of SError exception that can be synchronized by an Error Synchronization Barrier, then this bit is RES0.

The reset behavior of this field is:

Bits [30:12]

Reserved, RES0.

AET, bits [11:10]

Asynchronous Error Type. See the description of HSR.AET for an SError exception.

The reset behavior of this field is:

EA, bit [9]

External abort Type. See the description of HSR.EA for an SError exception.

The reset behavior of this field is:

Bits [8:6]

Reserved, RES0.

DFSC, bits [5:0]

Fault Status Code. See the description of HSR.DFSC for an SError exception.

The reset behavior of this field is:

When the ESB instruction is executed at EL0 or EL1 and where TTBCR.EAE == 0:

313029282726252423222120191817161514131211109876543210
ARES0AETRES0ExTRES0FS[4]LPAERES0FS[3:0]

A, bit [31]

Set to 1 when an ESB instruction defers an asynchronous SError exception. If the implementation does not include any sources of SError exception that can be synchronized by an Error Synchronization Barrier, then this bit is RES0.

The reset behavior of this field is:

Bits [30:16]

Reserved, RES0.

AET, bits [15:14]

Asynchronous Error Type. See the description of DFSR.AET for an SError exception.

The reset behavior of this field is:

Bit [13]

Reserved, RES0.

ExT, bit [12]

External abort Type. See the description of DFSR.ExT for an SError exception.

The reset behavior of this field is:

Bit [11]

Reserved, RES0.

FS, bits [10, 3:0]

Fault Status Code. See the description of DFSR.FS for an SError exception.

The FS field is split as follows:

The reset behavior of this field is:

LPAE, bit [9]

Format.

LPAEMeaning
0b0

Using the Short-descriptor translation table format.

The reset behavior of this field is:

Bits [8:4]

Reserved, RES0.

When the ESB instruction is executed at EL0 or EL1 and where TTBCR.EAE == 1:

313029282726252423222120191817161514131211109876543210
ARES0AETRES0ExTRES0LPAERES0STATUS

A, bit [31]

Set to 1 when an ESB instruction defers an asynchronous SError exception. If the implementation does not include any sources of SError exception that can be synchronized by an Error Synchronization Barrier, then this bit is RES0.

The reset behavior of this field is:

Bits [30:16]

Reserved, RES0.

AET, bits [15:14]

Asynchronous Error Type. See the description of DFSR.AET for an SError exception.

The reset behavior of this field is:

Bit [13]

Reserved, RES0.

ExT, bit [12]

External abort Type. See the description of DFSR.ExT for an SError exception.

The reset behavior of this field is:

Bits [11:10]

Reserved, RES0.

LPAE, bit [9]

Format.

LPAEMeaning
0b1

Using the Long-descriptor translation table format.

The reset behavior of this field is:

Bits [8:6]

Reserved, RES0.

STATUS, bits [5:0]

Fault Status Code. See the description of DFSR.FS for an SError exception.

The reset behavior of this field is:

Accessing DISR

An indirect write to DISR made by an ESB instruction does not require an explicit synchronization operation for the value that is written to be observed by a direct read of DISR occurring in program order after the ESB instruction.

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

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

coprocopc1CRnCRmopc2
0b11110b0000b11000b00010b001

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T12 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T12 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && (HCR_EL2.AMO == '1' || (IsFeatureImplemented(FEAT_DoubleFault2) && IsHCRXEL2Enabled() && HCRX_EL2.TMEA == '1')) then R[t] = VDISR_EL2<31:0>; elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.AMO == '1' then R[t] = VDISR; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && !Halted() && SCR_EL3.EA == '1' then R[t] = Zeros(32); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && !Halted() && SCR.EA == '1' then R[t] = Zeros(32); else R[t] = DISR; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && !Halted() && SCR_EL3.EA == '1' then R[t] = Zeros(32); elsif HaveEL(EL3) && ELUsingAArch32(EL3) && !Halted() && SCR.EA == '1' then R[t] = Zeros(32); else R[t] = DISR; elsif PSTATE.EL == EL3 then R[t] = DISR;

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

coprocopc1CRnCRmopc2
0b11110b0000b11000b00010b001

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T12 == '1' then AArch64.AArch32SystemAccessTrap(EL2, 0x03); elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T12 == '1' then AArch32.TakeHypTrapException(0x03); elsif EL2Enabled() && !ELUsingAArch32(EL2) && (HCR_EL2.AMO == '1' || (IsFeatureImplemented(FEAT_DoubleFault2) && IsHCRXEL2Enabled() && HCRX_EL2.TMEA == '1')) then VDISR_EL2 = R[t]; elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.AMO == '1' then VDISR = R[t]; elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && !Halted() && SCR_EL3.EA == '1' then return; elsif HaveEL(EL3) && ELUsingAArch32(EL3) && !Halted() && SCR.EA == '1' then return; else DISR = R[t]; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && !ELUsingAArch32(EL3) && !Halted() && SCR_EL3.EA == '1' then return; elsif HaveEL(EL3) && ELUsingAArch32(EL3) && !Halted() && SCR.EA == '1' then return; else DISR = R[t]; elsif PSTATE.EL == EL3 then DISR = R[t];