Stack Pointer (EL0)
Holds the stack pointer associated with EL0. At higher Exception levels, this is used as the current stack pointer when the value of SPSel.SP is 0.
This register is present only when FEAT_AA64 is implemented. Otherwise, direct accesses to SP_EL0 are UNDEFINED.
SP_EL0 is a 64-bit register.
| 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 |
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Stack pointer.
The reset behavior of this field is:
When the value of PSTATE.SP is 0, this register is accessible at all Exception levels as the current stack pointer.
Accesses to this register use the following encodings in the System register encoding space:
MRS <Xt>, SP_EL0
(op0 = 0b11, op1 = 0b000, CRn = 0b0100, CRm = 0b0001, op2 = 0b000)
if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if PSTATE.SP == '0' then UNDEFINED; else X[t, 64] = SP_EL0; elsif PSTATE.EL == EL2 then if PSTATE.SP == '0' then UNDEFINED; else X[t, 64] = SP_EL0; elsif PSTATE.EL == EL3 then if PSTATE.SP == '0' then UNDEFINED; else X[t, 64] = SP_EL0;
MSR SP_EL0, <Xt>
(op0 = 0b11, op1 = 0b000, CRn = 0b0100, CRm = 0b0001, op2 = 0b000)
if !IsFeatureImplemented(FEAT_AA64) then UNDEFINED; elsif PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if PSTATE.SP == '0' then UNDEFINED; else SP_EL0 = X[t, 64]; elsif PSTATE.EL == EL2 then if PSTATE.SP == '0' then UNDEFINED; else SP_EL0 = X[t, 64]; elsif PSTATE.EL == EL3 then if PSTATE.SP == '0' then UNDEFINED; else SP_EL0 = X[t, 64];
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