AT S1E1A

Purpose

Performs a stage 1 address translation, while ignoring the permission checks using the following translation regime:

When EL2 is implemented and enabled in the Security state described by the current Effective value of SCR_EL3.{NSE, NS}:

If the Effective value of HCR_EL2.{E2H, TGE} is not {1, 1}, the EL1&0 translation regime, accessed from EL1.
If the Effective value of HCR_EL2.{E2H, TGE} is {1, 1}, the EL2&0 translation regime, accessed from EL2.

Otherwise, the EL1&0 translation regime, accessed from EL1.

When FEAT_RME is implemented, if the Effective value of SCR_EL3.{NSE, NS} is a reserved value, this instruction is UNDEFINED at EL3.

Configuration

This instruction is present only when FEAT_ATS1A is implemented. Otherwise, direct accesses to AT S1E1A are UNDEFINED.

Attributes

Field descriptions

IA, bits [63:0]

Executing AT S1E1A

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

AT S1E1A, <Xt>

op0	op1	CRn	CRm	op2
0b01	0b000	0b0111	0b1001	0b010

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if EL2Enabled() && HCR_EL2.AT == '1' then AArch64.SystemAccessTrap(EL2, 0x18); elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGITR_EL2.ATS1E1A == '1' then AArch64.SystemAccessTrap(EL2, 0x18); else AArch64.AT(X[t, 64], TranslationStage_1, EL1, ATAccess_Any); elsif PSTATE.EL == EL2 then AArch64.AT(X[t, 64], TranslationStage_1, EL1, ATAccess_Any); elsif PSTATE.EL == EL3 then AArch64.AT(X[t, 64], TranslationStage_1, EL1, ATAccess_Any);

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
IA
IA

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
IA
IA

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
IA
IA

AT S1E1A, Address Translate Stage 1 EL1 Without Permission checks