ASM_FMT_M40
op = ASM_OP_PROBE_RW_FAULT, fmt = ASM_FMT_M40;
op = ASM_OP_PROBE_R_FAULT, fmt = ASM_FMT_M40;
op = ASM_OP_PROBE_W_FAULT, fmt = ASM_FMT_M40;
case ASM_FMT_M40: /* 0 dst */