ARM has been managing interruptible instructions with partial execution state for a long time. In ARM assembly syntax, the exclamation point in an addressing m

ARM has been managing interruptible instructions with partial execution state for a long time. In ARM assembly syntax, the exclamation point in an addressing mode indicates writeback. Its difficult to be certain without seeing the architecture reference manual, but it would be consistent for instruction to be writing back all three of the source pointer, destination pointer, and length registers. A memcpy is interruptible without replaying the entire instruction (say, because it hit a page that needed to be faulted-in by the operating system) if it wrote back a consistent view of all three registers prior to transferring control to an interrupt handler.