How to repair cracks in concrete overhang over entrance
You may need to approach this with some caution. It looks like the reinforcing steel is corroding from the picture. When this happens the steel expands and causes the concrete cover over the steel to spall off. Once the reinforcing bar looses its cover the rate of corrosion will increase and the bond between the steel and the concrete is substantially reduced. 

The problem is that just covering up the steel with a crack repair mortar may not fix the corrosion problem and either another section of the concrete could spall off or the repair mortar could spall off. I would suggest you get it looked at by a specialist. It doesn't look like it is in imminent risk of failure but just covering up the cracks may mean that you are hiding a long term problem.