You copied the Doc URL to your clipboard.

SPSel, Stack Pointer Select

The SPSel characteristics are:

Purpose

Allows the Stack Pointer to be selected between SP_EL0 and SP_ELx.

Configuration

There are no configuration notes.

Attributes

SPSel is a 64-bit register.

Field descriptions

The SPSel bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
RES0
RES0SP
313029282726252423222120191817161514131211109876543210

Bits [63:1]

Reserved, RES0.

SP, bit [0]

Stack pointer to use. Possible values of this bit are:

SPMeaning
0b0

Use SP_EL0 at all Exception levels.

0b1

Use SP_ELx for Exception level ELx.

On a Warm reset, this field resets to 1.

Accessing the SPSel

Accesses to this register use the following encodings:

MRS <Xt>, SPSel

op0op1CRnCRmop2
0b110b0000b01000b00100b000
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    return Zeros(63):PSTATE.SP;
elsif PSTATE.EL == EL2 then
    return Zeros(63):PSTATE.SP;
elsif PSTATE.EL == EL3 then
    return Zeros(63):PSTATE.SP;
              

MSR SPSel, <Xt>

op0op1CRnCRmop2
0b110b0000b01000b00100b000
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    PSTATE.SP = X[t]<0>;
elsif PSTATE.EL == EL2 then
    PSTATE.SP = X[t]<0>;
elsif PSTATE.EL == EL3 then
    PSTATE.SP = X[t]<0>;
              

MSR SPSel, #<imm>

op0op1CRnop2
0b000b0000b01000b101