GCSPR_EL1

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GCSPR_EL1, Guarded Control Stack Pointer Register (EL1)

Purpose

Configuration

This register is present only when FEAT_GCS is implemented. Otherwise, direct accesses to GCSPR_EL1 are UNDEFINED.

Attributes

Field descriptions

PTR[63:3], bits [63:3]

Bits [2:0]

Accessing GCSPR_EL1

When the Effective value of HCR_EL2.E2H is 1, without explicit synchronization, accesses from EL3 using the accessor name GCSPR_EL1 or GCSPR_EL12 are not guaranteed to be ordered with respect to accesses using the other accessor name.

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

MRS <Xt>, GCSPR_EL1

op0	op1	CRn	CRm	op2
0b11	0b000	0b0010	0b0101	0b001

if !IsFeatureImplemented(FEAT_GCS) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().GCSEn == '0' then Undefined(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3().FGTEn == '1') && HFGRTR_EL2().nGCS_EL1 == '0' then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3().GCSEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif EffectiveHCR_EL2_NVx() IN {'111'} then X{64}(t) = NVMem(0x8C0); else X{64}(t) = GCSPR_EL1(); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().GCSEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().GCSEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif ELIsInHost(EL2) then X{64}(t) = GCSPR_EL2(); else X{64}(t) = GCSPR_EL1(); end; elsif PSTATE.EL == EL3 then X{64}(t) = GCSPR_EL1(); end;

MSR GCSPR_EL1, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b000	0b0010	0b0101	0b001

if !IsFeatureImplemented(FEAT_GCS) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().GCSEn == '0' then Undefined(); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3().FGTEn == '1') && HFGWTR_EL2().nGCS_EL1 == '0' then AArch64_SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && SCR_EL3().GCSEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif EffectiveHCR_EL2_NVx() IN {'111'} then NVMem(0x8C0) = X{64}(t); else GCSPR_EL1() = X{64}(t); end; elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().GCSEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().GCSEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; elsif ELIsInHost(EL2) then GCSPR_EL2() = X{64}(t); else GCSPR_EL1() = X{64}(t); end; elsif PSTATE.EL == EL3 then GCSPR_EL1() = X{64}(t); end;

When FEAT_VHE is implemented

MRS <Xt>, GCSPR_EL12

op0	op1	CRn	CRm	op2
0b11	0b101	0b0010	0b0101	0b001

if !IsFeatureImplemented(FEAT_GCS) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() == '101' then X{64}(t) = NVMem(0x8C0); elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().GCSEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().GCSEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else X{64}(t) = GCSPR_EL1(); end; else Undefined(); end; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then X{64}(t) = GCSPR_EL1(); else Undefined(); end; end;

When FEAT_VHE is implemented

MSR GCSPR_EL12, <Xt>

op0	op1	CRn	CRm	op2
0b11	0b101	0b0010	0b0101	0b001

if !IsFeatureImplemented(FEAT_GCS) then Undefined(); elsif PSTATE.EL == EL0 then Undefined(); elsif PSTATE.EL == EL1 then if EffectiveHCR_EL2_NVx() == '101' then NVMem(0x8C0) = X{64}(t); elsif EffectiveHCR_EL2_NVx() IN {'xx1'} then AArch64_SystemAccessTrap(EL2, 0x18); else Undefined(); end; elsif PSTATE.EL == EL2 then if ELIsInHost(EL2) then if HaveEL(EL3) && EL3SDDUndefPriority() && SCR_EL3().GCSEn == '0' then Undefined(); elsif HaveEL(EL3) && SCR_EL3().GCSEn == '0' then if EL3SDDUndef() then Undefined(); else AArch64_SystemAccessTrap(EL3, 0x18); end; else GCSPR_EL1() = X{64}(t); end; else Undefined(); end; elsif PSTATE.EL == EL3 then if ELIsInHost(EL2) then GCSPR_EL1() = X{64}(t); else Undefined(); end; end;

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
PTR[63:3]
PTR[63:3]																													RES0