Techniques for signal handling between programs associated with different addressing modes in a computer system are described herein. An aspect includes, based on a signal occurring during execution of a first program in a first runtime environment, wherein the first program and the first runtime environment are associated with a first addressing mode, invoking a first signal exit routine associated with the first addressing mode. Another aspect includes allocating a signal information area (SIA) by the first signal exit routine. Another aspect includes calling a second signal exit routine associated with a second addressing mode that is different from the first addressing mode with an address of the SIA. Another aspect includes allocating a mirror SIA by the second signal exit routine. Another aspect includes handling the signal, and resuming execution based on the handling of the signal.