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DC CGVAC, Data, Allocation Tag or unified Cache line Clean of Allocation Tags by VA to PoC

The DC CGVAC characteristics are:

Purpose

Clean Allocation Tags in data cache by address to Point of Coherency.

Configuration

This instruction is present only when ARMv8.5-MemTag is implemented. Otherwise, direct accesses to DC CGVAC are UNDEFINED.

Attributes

DC CGVAC is a 64-bit System instruction.

Field descriptions

The DC CGVAC input value bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
Virtual address to use
Virtual address to use
313029282726252423222120191817161514131211109876543210

Bits [63:0]

Virtual address to use. No alignment restrictions apply to this VA.

Executing the DC CGVAC instruction

If EL0 access is enabled, when executed at EL0, this instruction requires read access permission to the VA, otherwise it generates a Permission Fault, subject to the constraints described in 'Permission fault' in the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile.

Execution of this instruction might require an address translation from VA to PA, and that translation might fault. For more information, see 'The data cache maintenance instruction (DC)' in the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile.

Accesses to this instruction use the following encodings:

DC CGVAC, <Xt>

op0CRnop1op2CRm
0b010b01110b0110b0110b1010
if PSTATE.EL == EL0 then
    if !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && SCTLR_EL1.UCI == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.SystemAccessTrap(EL2, 0x18);
        else
            AArch64.SystemAccessTrap(EL1, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> != '11' && HCR_EL2.TPCP == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCTLR_EL2.UCI == '0' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        DC_CGVAC(X[t]);
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TPCP == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    else
        DC_CGVAC(X[t]);
elsif PSTATE.EL == EL2 then
    DC_CGVAC(X[t]);
elsif PSTATE.EL == EL3 then
    DC_CGVAC(X[t]);
              


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