A mechanism is provided for accessing, by an application running on a first processor, operating system services from an operating system running on a second processor by performing an assisted call. A data plane processor first constructs a parameter area based on the input and output parameters for the function that requires control processor assistance. The current values for the input parameters are copied into the parameter area. An assisted call message is generated based on a combination of a pointer to the parameter area and a specific library function opcode for the library function that is being called. The assisted call message is placed into the processor's stack immediately following a stop-and-signal instruction. The control plane processor is signaled to perform the library function corresponding to the opcode on behalf of the data plane processor by executing a stop and signal instruction.