There is no such thing as "reverse racism" or "reverse sexism". Reverse racism is racism. Reverse sexism is sexism.
Racism is discriminating against an individual based on their race. Regardless of what their race is. Same goes for sexism.
Being racist or sexist has nothing to do with the general attitude of society or a history of oppression. It is about plain discrimination which means "reverse racism/ sexism" are terms devoid of any form of rationality.