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CP15DMB, Data Memory Barrier System instruction

The CP15DMB characteristics are:

Purpose

Performs a Data Memory Barrier.

Arm deprecates any use of this System instruction, and strongly recommends that software use the DMB instruction instead.

Configuration

Attributes

CP15DMB is a 32-bit System instruction.

Field descriptions

CP15DMB ignores the value in the register specified by the instruction encoding. Software does not have to write a value to the register before issuing this instruction.

Executing the CP15DMB instruction

Accesses to this instruction use the following encodings:

MCR{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <CRn>, <CRm>{, {#}<opc2>}

coprocopc1CRnCRmopc2
0b11110b0000b01110b10100b101
if PSTATE.EL == EL0 then
    if !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && SCTLR_EL1.CP15BEN == '0' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && SCTLR_EL2.CP15BEN == '0' then
        UNDEFINED;
    elsif ELUsingAArch32(EL1) && SCTLR.CP15BEN == '0' then
        UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> != '11' && HSTR_EL2.T7 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T7 == '1' then
        AArch32.TakeHypTrapException(0x03);
    else
        CP15DMB();
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && HSTR_EL2.T7 == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x03);
    elsif EL2Enabled() && ELUsingAArch32(EL2) && HSTR.T7 == '1' then
        AArch32.TakeHypTrapException(0x03);
    elsif ELUsingAArch32(EL1) && SCTLR.CP15BEN == '0' then
        UNDEFINED;
    else
        CP15DMB();
elsif PSTATE.EL == EL2 then
    if HSCTLR.CP15BEN == '0' then
        UNDEFINED;
    else
        CP15DMB();
elsif PSTATE.EL == EL3 then
    CP15DMB();


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