Q: My car leaked all the oil from underneath the car

This suggests you may have a leak resulting from a failing gasket somewhere in your engine. As you know, there are many different places in your motor that are sealed by gaskets. I would suggest narrowing this down by placing a piece of cardboard underneath the vehicle when parking it at night to test for a couple of things. Number one, does it leak when the motor is not running or otherwise under pressure and two, approximately where under the vehicle does the leak come from. Gaskets can fail over time due to excessive heat and will eventually shrink causing them to fail and leak. The white smoke is likely the oil leaking and being burned off on the hot engine or potentially being burnt inside the motor as a result of an internal oil leak. I would recommend having an expert from YourMechanic come to your location to diagnose and repair your oil leak.