DSPSR | Jon's Arm Reference

Holds the saved process state for Debug state. On entering Debug state, PSTATE information is written to this register. On exiting Debug state, values are copied from this register to PSTATE.

Configuration

AArch32 System register DSPSR bits [31:0] are architecturally mapped to AArch64 System register DSPSR_EL0[31:0].

This register is present only when AArch32 is supported. Otherwise, direct accesses to DSPSR are UNDEFINED.

Attributes

Field descriptions

N, bit [31]

Negative Condition flag. Set to the value of PSTATE.N on entering Debug state, and copied to PSTATE.N on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Z, bit [30]

Zero Condition flag. Set to the value of PSTATE.Z on entering Debug state, and copied to PSTATE.Z on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

C, bit [29]

Carry Condition flag. Set to the value of PSTATE.C on entering Debug state, and copied to PSTATE.C on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

V, bit [28]

Overflow Condition flag. Set to the value of PSTATE.V on entering Debug state, and copied to PSTATE.V on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Q, bit [27]

Overflow or saturation flag. Set to the value of PSTATE.Q on entering Debug state, and copied to PSTATE.Q on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

IT, bits [15:10, 26:25]

If-Then. Set to the value of PSTATE.IT on entering Debug state, and copied to PSTATE.IT on exiting Debug state.

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

The IT field is split as follows:

IT[1:0] is DSPSR[26:25].
IT[7:2] is DSPSR[15:10].

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

DIT, bit [24]

When FEAT_DIT is implemented:

Data Independent Timing. Set to the value of PSTATE.DIT on entering Debug state, and copied to PSTATE.DIT on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Otherwise:

SSBS, bit [23]

When FEAT_SSBS is implemented:

Speculative Store Bypass. Set to the value of PSTATE.SSBS on entering Debug state, and copied to PSTATE.SSBS on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Otherwise:

PAN, bit [22]

When FEAT_PAN is implemented:

Privileged Access Never. Set to the value of PSTATE.PAN on entering Debug state, and copied to PSTATE.PAN on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Otherwise:

SS, bit [21]

Software Step. Set to the value of PSTATE.SS on entering Debug state, and conditionally copied to PSTATE.SS on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

IL, bit [20]

Illegal Execution state. Set to the value of PSTATE.IL on entering Debug state, and copied to PSTATE.IL on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, 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 entering Debug state, and copied to PSTATE.GE on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

E, bit [9]

Endianness. Set to the value of PSTATE.E on entering Debug state, and copied to PSTATE.E on exiting Debug state.

If the implementation does not support big-endian operation, DSPSR.E is RES0. If the implementation does not support little-endian operation, DSPSR.E is RES1. On exiting Debug state, if the implementation does not support big-endian operation at the Exception level being returned to, DSPSR.E is RES0, and if the implementation does not support little-endian operation at the Exception level being returned to, DSPSR.E is RES1.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

A, bit [8]

SError exception mask. Set to the value of PSTATE.A on entering Debug state, and copied to PSTATE.A on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

I, bit [7]

IRQ interrupt mask. Set to the value of PSTATE.I on entering Debug state, and copied to PSTATE.I on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

F, bit [6]

FIQ interrupt mask. Set to the value of PSTATE.F on entering Debug state, and copied to PSTATE.F on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

T, bit [5]

T32 Instruction set state. Set to the value of PSTATE.T on entering Debug state, and copied to PSTATE.T on exiting Debug state.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

M[4:0], bits [4:0]

Mode. Set to the value of PSTATE.M[4:0] on entering Debug state, and copied to PSTATE.M[4:0] on exiting Debug state.

M[4:0]	Meaning
0b10000	User.
0b10001	FIQ.
0b10010	IRQ.
0b10011	Supervisor.
0b10110	Monitor.
0b10111	Abort.
0b11010	Hyp.
0b11011	Undefined.
0b11111	System.

Other values are reserved. If DSPSR.M[4:0] has a Reserved value, or a value for an unimplemented Exception level, exiting Debug state is an illegal return event, as described in 'Illegal return events from AArch32 state'.

The reset behavior of this field is:

On a Warm reset, this field resets to an architecturally UNKNOWN value.

Accessing DSPSR

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

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b011	0b0100	0b0101	0b000

if !Halted() then UNDEFINED; else R[t] = DSPSR;

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

coproc	opc1	CRn	CRm	opc2
0b1111	0b011	0b0100	0b0101	0b000

if !Halted() then UNDEFINED; else DSPSR = R[t];

DSPSR: Debug Saved Program Status Register

Purpose

Configuration

Attributes

Field descriptions

N, bit [31]

Z, bit [30]

C, bit [29]

V, bit [28]

Q, bit [27]

IT, bits [15:10, 26:25]

DIT, bit [24]

When FEAT_DIT is implemented:

Otherwise:

SSBS, bit [23]

When FEAT_SSBS is implemented:

Otherwise:

PAN, bit [22]

When FEAT_PAN is implemented:

Otherwise:

SS, bit [21]

IL, bit [20]

GE, bits [19:16]

E, bit [9]

A, bit [8]

I, bit [7]

F, bit [6]

T, bit [5]

M[4:0], bits [4:0]

Accessing DSPSR

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

DSPSR: Debug Saved Program Status Register

Purpose

Configuration

Attributes

Field descriptions

N, bit [31]

Z, bit [30]

C, bit [29]

V, bit [28]

Q, bit [27]

IT, bits [15:10, 26:25]

DIT, bit [24]When FEAT_DIT is implemented:

Otherwise:

SSBS, bit [23]When FEAT_SSBS is implemented:

Otherwise:

PAN, bit [22]When FEAT_PAN is implemented:

Otherwise:

SS, bit [21]

IL, bit [20]

GE, bits [19:16]

E, bit [9]

A, bit [8]

I, bit [7]

F, bit [6]

T, bit [5]

M[4:0], bits [4:0]

Accessing DSPSR

DIT, bit [24]

When FEAT_DIT is implemented:

SSBS, bit [23]

When FEAT_SSBS is implemented:

PAN, bit [22]

When FEAT_PAN is implemented: