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BPIALL, Branch Predictor Invalidate All

The BPIALL characteristics are:

Purpose

Invalidate all entries from branch predictors.

Configuration

This instruction is present only when AArch32 is supported at any Exception level. Otherwise, direct accesses to BPIALL are UNKNOWN.

In an implementation where the branch predictors are architecturally invisible, this instruction can execute as a NOP.

Attributes

BPIALL is a 32-bit System instruction.

Field descriptions

BPIALL 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 BPIALL instruction

The PE ignores the value of <Rt>. Software does not have to write a value to this register before issuing this instruction.

When HCR.FB is 1, at Non-secure EL1 this instruction executes as a BPIALLIS.

Accesses to this instruction use the following encodings:

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

coprocopc1CRnCRmopc2
0b11110b0000b01110b01010b110
if PSTATE.EL == EL0 then
    UNDEFINED;
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 EL2Enabled() && ELUsingAArch32(EL2) && HCR.FB == '1' then
        BPIALLIS();
    else
        BPIALL();
elsif PSTATE.EL == EL2 then
    BPIALL();
elsif PSTATE.EL == EL3 then
    BPIALL();