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software breakpoint

A breakpoint made by temporarily writing a special trap instruction over the program's code at the chosen spot.

A software breakpoint replaces the first byte(s) of the target instruction with a breakpoint instruction (x86-64 int3, 0xCC; ARM64 brk; RISC-V ebreak); executing it raises a debug trap the debugger receives, which restores the original bytes, rewinds the PC where needed and single-steps the real instruction before re-inserting the trap. There is no limit on how many can be set.

Examples

  • On x86-64 a debugger writes the 1-byte int3 (0xCC) over an instruction's first byte; on ARM64 it writes a brk instruction.

See also

breakpoint debugger
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