B2.20 ATCR_EL12 , Alias to Auxiliary Translation Control Register EL1

The ATCR_EL12 alias allows access to ATCR_EL1 at EL2 or EL3 when HCR_EL2.E2H is set to 1.

This register is only used when Page Based Hardware Attributes (PBHA) is configured by the core.

Usage constraints

Accessing the ATCR_EL12

To access the ATCR_EL1using the ATCR_EL12 alias:

MRS Xt , S< 3   5  c15   c7  0> ; Read ATCR_EL12/ATCR_EL1 into Xt  
MSR S < 3   5  c15   c7  0 > , Xt   ; Write Xt to ATCR_EL12/ATCR_EL1

This syntax is encoded with the following settings in the instruction encoding:

Op0 Op1 CRn CRm Op2
3 5 15 7 0
Accessibility

ATCR_EL12 is accessible as follows:

  Control Accessibility
E2H TGE NS EL0 EL1 EL2 EL3
ATCR_EL12 x x 0 - - n/a -
ATCR_EL12 0 0 1 - - - -
ATCR_EL12 0 1 1 - n/a - -
ATCR_EL12 1 0 1 - - ATCR_EL1 ATCR_EL1
ATCR_EL12 1 1 1 - n/a ATCR_EL1 ATCR_EL1
Traps and enables

All traps associated with the ATCR_EL1 register that apply at EL2 or EL3 also apply to the ATCR_EL12 alias.

This alias is only accessible when HCR_EL2.E2H == 1.

When HCR_EL2.E2H == 0, access to this alias is UNDEFINED.

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