How do I report the earnings on my roth ira withdrawal?

how do I report the earnings on my roth ira withdrawal?

i'm 63, i took an early withdrawal (held <5 years).

received a 1099-r that shows a gross distribution ($10k), the distribution code is t & shows tax amount not determined. 

is there a way to obtain the cost of the gross distribution. use box 8 and 9a for cost/contribution-withdrawal?