clrex

Clear Exclusive (System)

CLREX {#<imm>}

Clears the local monitor state (AArch64 variant).

Details

Clears the local monitor state associated with the current PE, removing any exclusive accesses held by this processor. Subsequent LDEX/STEX instructions will treat the exclusive monitor as clear. Does not update condition flags. AArch64 only; optional immediate operand is typically 0xF (ignored).

Pseudocode Operation

local_monitor_state ← CLEAR

Example

CLREX

Encoding

Binary Layout

11010101000000110011

CRm

010

11111

Format System

Opcode 0xD503305F

Extension Base (Atomic)

Operands

imm
Optional

Reference (Arm A64 ISA)

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xD503305F	CLREX {#<imm>}		A64		11010101000000110011 \| CRm \| 010 \| 11111

Description

Clear Exclusive clears the local monitor of the executing PE.

Operation

ClearExclusiveLocal(ProcessorID());