BRB IALL, Invalidate the Branch Record Buffer

The BRB IALL characteristics are:

Purpose

Invalidates all Branch records in the Branch Record Buffer.

Configuration

This instruction is present only when FEAT_BRBE is implemented. Otherwise, direct accesses to BRB IALL are UNDEFINED.

Attributes

BRB IALL is a 64-bit System instruction.

Field descriptions

This instruction has no applicable fields.

The value in the register specified by <Xt> is ignored.

Executing BRB IALL

Rt should be encoded as 0b11111. If the Rt field is not set to 0b11111, it is CONSTRAINED UNPREDICTABLE whether:

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

BRB IALL

op0op1CRnCRmop2
0b010b0010b01110b00100b100

if PSTATE.EL == EL0 then UNDEFINED; elsif PSTATE.EL == EL1 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE IN {'x0'} && SCR_EL3.NS == '1' then UNDEFINED; elsif EL2Enabled() && IsFeatureImplemented(FEAT_FGT) && (!HaveEL(EL3) || SCR_EL3.FGTEn == '1') && HFGITR_EL2.nBRBIALL == '0' then AArch64.SystemAccessTrap(EL2, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE IN {'x0'} && SCR_EL3.NS == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else BRB_IALL(); elsif PSTATE.EL == EL2 then if HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then UNDEFINED; elsif HaveEL(EL3) && EL3SDDUndefPriority() && MDCR_EL3.SBRBE IN {'x0'} && SCR_EL3.NS == '1' then UNDEFINED; elsif HaveEL(EL3) && MDCR_EL3.SBRBE != '11' && SCR_EL3.NS == '0' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); elsif HaveEL(EL3) && MDCR_EL3.SBRBE IN {'x0'} && SCR_EL3.NS == '1' then if EL3SDDUndef() then UNDEFINED; else AArch64.SystemAccessTrap(EL3, 0x18); else BRB_IALL(); elsif PSTATE.EL == EL3 then BRB_IALL();


26/03/2024 09:49; 67c0ae5282a7629ba0ea0ba7267b43cd4f7939f6

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