SP_EL0, Stack Pointer (EL0)

The SP_EL0 characteristics are:

Purpose

Holds the capability stack pointer associated with EL0 and Executive state. At higher Exception levels, this is used as the current capability stack pointer when the value of SPSel.SP is 0 and the PE is in Executive.

Configuration

RW fields in this register reset to architecturally UNKNOWN values.

Attributes

SP_EL0 is a 129-bit register.

Field descriptions

The SP_EL0 bit assignments are:

When Morello is implemented:

Bits [128:0]

Stack pointer

This field resets to an architecturally UNKNOWN value.

When Morello is not implemented:

6362616059585756555453525150494847464544434241403938373635343332
Stack pointer
Stack pointer
313029282726252423222120191817161514131211109876543210

Bits [63:0]

Stack pointer.

This field resets to an architecturally UNKNOWN value.

Accessing the SP_EL0

When the value of PSTATE.SP is 0 and the PE is in Executive, this register is accessible at all Exception levels as the current stack pointer.

Accesses to this register use the following encodings:

MRS <Xt>, SP_EL0

op0op1CRnCRmop2
0b110b0000b01000b00010b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; else return SP_EL0<63:0>; elsif PSTATE.EL == EL2 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; else return SP_EL0<63:0>; elsif PSTATE.EL == EL3 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; else return SP_EL0<63:0>;

MSR SP_EL0, <Xt>

op0op1CRnCRmop2
0b110b0000b01000b00010b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; else SP_EL0 = ZeroExtend(X[t]); elsif PSTATE.EL == EL2 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; else SP_EL0 = ZeroExtend(X[t]); elsif PSTATE.EL == EL3 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; else SP_EL0 = ZeroExtend(X[t]);

MRS <Ct>, CSP_EL0

op0op1CRnCRmop2
0b110b0000b01000b00010b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; elsif CPACR_EL1.CEN == 'x0' then AArch64.SystemAccessTrap(EL1, 0x29); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.E2H != '1' && CPTR_EL2.TC == '1' then AArch64.SystemAccessTrap(EL2, 0x29); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.E2H == '1' && CPTR_EL2.CEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x29); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.EC == '0' then AArch64.SystemAccessTrap(EL3, 0x29); else return SP_EL0; elsif PSTATE.EL == EL2 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; elsif HCR_EL2.E2H == '0' && CPTR_EL2.TC == '1' then AArch64.SystemAccessTrap(EL2, 0x29); elsif HCR_EL2.E2H == '1' && CPTR_EL2.CEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x29); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.EC == '0' then AArch64.SystemAccessTrap(EL3, 0x29); else return SP_EL0; elsif PSTATE.EL == EL3 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; elsif CPTR_EL3.EC == '0' then AArch64.SystemAccessTrap(EL3, 0x29); else return SP_EL0;

MSR CSP_EL0, <Ct>

op0op1CRnCRmop2
0b110b0000b01000b00010b000

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; elsif CPACR_EL1.CEN == 'x0' then AArch64.SystemAccessTrap(EL1, 0x29); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.E2H != '1' && CPTR_EL2.TC == '1' then AArch64.SystemAccessTrap(EL2, 0x29); elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.E2H == '1' && CPTR_EL2.CEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x29); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.EC == '0' then AArch64.SystemAccessTrap(EL3, 0x29); else SP_EL0 = C[t]; elsif PSTATE.EL == EL2 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; elsif HCR_EL2.E2H == '0' && CPTR_EL2.TC == '1' then AArch64.SystemAccessTrap(EL2, 0x29); elsif HCR_EL2.E2H == '1' && CPTR_EL2.CEN == 'x0' then AArch64.SystemAccessTrap(EL2, 0x29); elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && CPTR_EL3.EC == '0' then AArch64.SystemAccessTrap(EL3, 0x29); else SP_EL0 = C[t]; elsif PSTATE.EL == EL3 then if PSTATE.SP == '0' then UNDEFINED; elsif IsFeatureImplemented("Morello") && IsInRestricted() && !Halted() then UNDEFINED; elsif CPTR_EL3.EC == '0' then AArch64.SystemAccessTrap(EL3, 0x29); else SP_EL0 = C[t];




12/01/2022 09:56; 05a4944b4b04e7ab50def8c126b479d22136f35b

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