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# SPSR_EL3, Saved Program Status Register (EL3)

The SPSR_EL3 characteristics are:

## Purpose

Holds the saved process state when an exception is taken to EL3.

## Configuration

AArch64 System register SPSR_EL3 bits [31:0] can be mapped to AArch32 System register SPSR_mon[31:0] , but this is not architecturally mandated.

RW fields in this register reset to architecturally UNKNOWN values.

## Attributes

SPSR_EL3 is a 64-bit register.

## Field descriptions

The SPSR_EL3 bit assignments are:

### When exception taken from AArch32 state:

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
RES0
N | Z | C | V | Q | IT[1:0] | DIT | SSBS | PAN | SS | IL | GE | IT[7:2] | E | A | I | F | T | M[4] | M[3:0]
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

An exception return from EL3 using AArch64 makes SPSR_EL1 become UNKNOWN.

#### Bits [63:32]

Reserved, RES0.

#### N, bit [31]

Negative Condition flag. Set to the value of PSTATE.N on taking an exception to EL3, and copied to PSTATE.N on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### Z, bit [30]

Zero Condition flag. Set to the value of PSTATE.Z on taking an exception to EL3, and copied to PSTATE.Z on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### C, bit [29]

Carry Condition flag. Set to the value of PSTATE.C on taking an exception to EL3, and copied to PSTATE.C on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### V, bit [28]

Overflow Condition flag. Set to the value of PSTATE.V on taking an exception to EL3, and copied to PSTATE.V on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### Q, bit [27]

Overflow or saturation flag. Set to the value of PSTATE.Q on taking an exception to EL3, and copied to PSTATE.Q on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### IT[1:0], bits [26:25]

If-Then. Set to the value of PSTATE.IT[1:0] on taking an exception to EL3, and copied to PSTATE.IT[1:0] on executing an exception return operation in EL3.

On executing an exception return operation in EL3 SPSR_EL1.IT must contain a value that is valid for the instruction being returned to.

This field resets to an architecturally UNKNOWN value.

#### DIT, bit [24]
When ARMv8.4-DIT is implemented:

Data Independent Timing. Set to the value of PSTATE.DIT on taking an exception to EL3, and copied to PSTATE.DIT on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

####
Otherwise:

Reserved, RES0.

#### SSBS, bit [23]
When ARMv8.0-SSBS is implemented:

Speculative Store Bypass. Set to the value of PSTATE.SSBS on taking an exception to EL3, and copied to PSTATE.SSBS on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

####
Otherwise:

Reserved, RES0.

#### PAN, bit [22]
When ARMv8.1-PAN is implemented:

Privileged Access Never. Set to the value of PSTATE.PAN on taking an exception to EL3, and copied to PSTATE.PAN on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

####
Otherwise:

Reserved, RES0.

#### SS, bit [21]

Software Step. Set to the value of PSTATE.SS on taking an exception to EL3, and conditionally copied to PSTATE.SS on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### IL, bit [20]

Illegal Execution state. Set to the value of PSTATE.IL on taking an exception to EL3, and copied to PSTATE.IL on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### GE, bits [19:16]

Greater than or Equal flags. Set to the value of PSTATE.GE on taking an exception to EL3, and copied to PSTATE.GE on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### IT[7:2], bits [15:10]

If-Then. Set to the value of PSTATE.IT[7:2] on taking an exception to EL3, and copied to PSTATE.IT[7:2] on executing an exception return operation in EL3.

SPSR_EL1.IT must contain a value that is valid for the instruction being returned to.

This field resets to an architecturally UNKNOWN value.

#### E, bit [9]

Endianness. Set to the value of PSTATE.E on taking an exception to EL3, and copied to PSTATE.E on executing an exception return operation in EL3.

If the implementation does not support big-endian operation, SPSR_EL1.E is RES0. If the implementation does not support little-endian operation, SPSR_EL1.E is RES1. On executing an exception return operation in EL3, if the implementation does not support big-endian operation at the Exception level being returned to, SPSR_EL1.E is RES0, and if the implementation does not support little-endian operation at the Exception level being returned to, SPSR_EL1.E is RES1.

This field resets to an architecturally UNKNOWN value.

#### A, bit [8]

SError interrupt mask. Set to the value of PSTATE.A on taking an exception to EL3, and copied to PSTATE.A on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### I, bit [7]

IRQ interrupt mask. Set to the value of PSTATE.I on taking an exception to EL3, and copied to PSTATE.I on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### F, bit [6]

FIQ interrupt mask. Set to the value of PSTATE.F on taking an exception to EL3, and copied to PSTATE.F on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### T, bit [5]

T32 Instruction set state. Set to the value of PSTATE.T on taking an exception to EL3, and copied to PSTATE.T on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### M[4], bit [4]

Execution state. Set to 0b1, the value of PSTATE.nRW, on taking an exception to EL3 from AArch32 state, and copied to PSTATE.nRW on executing an exception return operation in EL3.

M[4] | Meaning
--- | ---
0b1 | AArch32 execution state.

This field resets to an architecturally UNKNOWN value.

#### M[3:0], bits [3:0]

AArch32 Mode. Set to the value of PSTATE.M[3:0] on taking an exception to EL3, and copied to PSTATE.M[3:0] on executing an exception return operation in EL3.

M[3:0] | Meaning
--- | ---
0b0000 | User.
0b0001 | FIQ.
0b0010 | IRQ.
0b0011 | Supervisor.
0b0110 | Monitor.
0b0111 | Abort.
0b1010 | Hyp.
0b1011 | Undefined.
0b1111 | System.

Other values are reserved. If SPSR_EL1.M[3:0] has a Reserved value, or a value for an unimplemented Exception level, executing an exception return operation in EL3 is an illegal return event, as described in 'Illegal return events from AArch64 state' in the Arm®Architecture Reference Manual, Armv8, for Armv8-A architecture profile.

This field resets to an architecturally UNKNOWN value.

### When exception taken from AArch64 state:

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
RES0
N | Z | C | V | RES0 | TCO | DIT | UAO | PAN | SS | IL | RES0 | SSBS | BTYPE | D | A | I | F | RES0 | M[4] | M[3:0]
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

An exception return from EL3 using AArch64 makes SPSR_EL1 become UNKNOWN.

#### Bits [63:32]

Reserved, RES0.

#### N, bit [31]

Negative Condition flag. Set to the value of PSTATE.N on taking an exception to EL3, and copied to PSTATE.N on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### Z, bit [30]

Zero Condition flag. Set to the value of PSTATE.Z on taking an exception to EL3, and copied to PSTATE.Z on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### C, bit [29]

Carry Condition flag. Set to the value of PSTATE.C on taking an exception to EL3, and copied to PSTATE.C on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### V, bit [28]

Overflow Condition flag. Set to the value of PSTATE.V on taking an exception to EL3, and copied to PSTATE.V on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### Bits [27:26]

Reserved, RES0.

#### TCO, bit [25]
When ARMv8.5-MemTag is implemented:

Tag Check Override. Set to the value of PSTATE.TCO on taking an exception to EL3, and copied to PSTATE.TCO on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

####
Otherwise:

Reserved, RES0.

#### DIT, bit [24]
When ARMv8.4-DIT is implemented:

Data Independent Timing. Set to the value of PSTATE.DIT on taking an exception to EL3, and copied to PSTATE.DIT on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

####
Otherwise:

Reserved, RES0.

#### UAO, bit [23]
When ARMv8.2-UAO is implemented:

User Access Override. Set to the value of PSTATE.UAO on taking an exception to EL3, and copied to PSTATE.UAO on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

####
Otherwise:

Reserved, RES0.

#### PAN, bit [22]
When ARMv8.1-PAN is implemented:

Privileged Access Never. Set to the value of PSTATE.PAN on taking an exception to EL3, and copied to PSTATE.PAN on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

####
Otherwise:

Reserved, RES0.

#### SS, bit [21]

Software Step. Set to the value of PSTATE.SS on taking an exception to EL3, and conditionally copied to PSTATE.SS on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### IL, bit [20]

Illegal Execution state. Set to the value of PSTATE.IL on taking an exception to EL3, and copied to PSTATE.IL on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### Bits [19:13]

Reserved, RES0.

#### SSBS, bit [12]
When ARMv8.0-SSBS is implemented:

Speculative Store Bypass. Set to the value of PSTATE.SSBS on taking an exception to EL3, and copied to PSTATE.SSBS on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

####
Otherwise:

Reserved, RES0.

#### BTYPE, bits [11:10]
When ARMv8.5-BTI is implemented:

Branch Type Indicator. Set to the value of PSTATE.BTYPE on taking an exception to EL3, and copied to PSTATE.BTYPE on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

####
Otherwise:

Reserved, RES0.

#### D, bit [9]

Debug exception mask. Set to the value of PSTATE.D on taking an exception to EL3, and copied to PSTATE.D on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### A, bit [8]

SError interrupt mask. Set to the value of PSTATE.A on taking an exception to EL3, and copied to PSTATE.A on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### I, bit [7]

IRQ interrupt mask. Set to the value of PSTATE.I on taking an exception to EL3, and copied to PSTATE.I on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### F, bit [6]

FIQ interrupt mask. Set to the value of PSTATE.F on taking an exception to EL3, and copied to PSTATE.F on executing an exception return operation in EL3.

This field resets to an architecturally UNKNOWN value.

#### Bit [5]

Reserved, RES0.

#### M[4], bit [4]

Execution state. Set to 0b0, the value of PSTATE.nRW, on taking an exception to EL3 from AArch64 state, and copied to PSTATE.nRW on executing an exception return operation in EL3.

M[4] | Meaning
--- | ---
0b0 | AArch64 execution state.

If AArch32 is not supported at any Exception level, this bit is RES0.

This field resets to an architecturally UNKNOWN value.

#### M[3:0], bits [3:0]

AArch64 Exception level and selected Stack Pointer.

M[3:0] | Meaning
--- | ---
0b0000 | EL0t.
0b0100 | EL1t.
0b0101 | EL1h.
0b1000 | EL2t.
0b1001 | EL2h.
0b1100 | EL3t.
0b1101 | EL3h.

Other values are reserved. If SPSR_EL1.M[3:0] has a Reserved value, or a value for an unimplemented Exception level, executing an exception return operation in EL3 is an illegal return event, as described in 'Illegal return events from AArch64 state' in the Arm®Architecture Reference Manual, Armv8, for Armv8-A architecture profile.

The bits in this field are interpreted as follows:

- M[3:2] is set to the value of PSTATE.EL on taking an exception to EL3 and copied to PSTATE.EL on executing an exception return operation in EL3.
- M[1] is unused and is 0 for all non-reserved values.
- M[0] is set to the value of PSTATE.SP on taking an exception to EL3 and copied to PSTATE.SP on executing an exception return operation in EL3

This field resets to an architecturally UNKNOWN value.

## Accessing the SPSR_EL3

Accesses to this register use the following encodings:

#### MRS <Xt>, SPSR_EL3

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b110 | 0b0100 | 0b0000 | 0b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then UNDEFINED; elsif PSTATE.EL == EL2 then UNDEFINED; elsif PSTATE.EL == EL3 then return SPSR_EL3;

#### MSR SPSR_EL3, <Xt>

op0 | op1 | CRn | CRm | op2
--- | --- | --- | --- | ---
0b11 | 0b110 | 0b0100 | 0b0000 | 0b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then UNDEFINED; elsif PSTATE.EL == EL2 then UNDEFINED; elsif PSTATE.EL == EL3 then SPSR_EL3 = X[t];

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

27/03/2019 21:59; e5e4db499bf9867a4b93324c4dbac985d3da9376

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