In the vicinity of a Schwarzchild black hole, spacetime looks like this (at least according to a quick google search). Here, the centre of the black hole is supposed to be at $x=0$ and the event horizon at $x=3$. And outside the event horizon, the future light cones look pretty normal, except they kind of bend upwards.
But what would a diagram like this look like if we swapped the black hole for a white hole? Which way would the light cones bend?