brk

Breakpoint

BRK #<imm>

Generates a Breakpoint instruction exception.

Details

Generate a breakpoint exception (ESR_ELx.EC = 0x3C). The 16-bit immediate is encoded in the instruction and passed to the exception handler but does not affect architectural state. Execution does not proceed to the next instruction unless the exception handler explicitly resumes. This is an AArch64-only instruction.

Pseudocode Operation

AArch64.SystemSideEffect()
ESR_ELx.EC ← 0x3C
ESR_ELx.ISS ← imm16
TakeSynchronousException(Breakpoint)

Example

BRK #16

Encoding

Binary Layout

11010100

001

imm16

000

Format Exception

Opcode 0xD4200000

Extension Base

Operands

imm
ID (16-bit)

Reference (Arm A64 ISA)

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0xD4200000	BRK #<imm>		A64		11010100 \| 001 \| imm16 \| 000 \| 00

Description

Breakpoint instruction. A BRK instruction generates a Breakpoint Instruction exception. The PE records the exception in ESR_ELx, using the EC value 0x3C, and captures the value of the immediate argument in ESR_ELx.ISS. Within a guarded memory region, while PSTATE.BTYPE != 0b00, a BRK instruction will not generate a Branch Target Exception and will generate a Breakpoint Instruction exception as normal. For more information, see PSTATE.BTYPE.

Operation

AArch64.SoftwareBreakpoint(imm16);