What kind of damage is in this attic wall?
Looks like, but may not be,  water staining on concrete which in and of itself is not damage per-say. 

But it raises the question of  how and why did water get to it and what water damage may or may not be in the non-concrete construction part of the house above it. 

I would guess a roof leak around where this concrete exits the roof or compromise in the concrete itself above the roof line. 

No way to know about the cost of repairs until one knows the extent of damage, if any, to the rest of the house.