White substance beneath penis upper skin

From what you have described it appears like fungal balaniposthetis. It's fungal infection more commonly seen in uncircumcised males . You can consult your dr for further treatment in meantime I suggest following measures To prevent infections, the head of the penis and the foreskin should be kept clean and dry. Daily washing, with particular attention to cleaning the penis, is essential. Here are some hygiene tips: The foreskin should be pulled back so that the glans is exposed.The area should be washed thoroughly and gently with warm water. Soap may irritate, so it should be avoided.An aqueous cream or some other neutral nonsoap cleanser may be used, but it should be completely rinsed off.Before replacing the foreskin, the glans should be completely dry.Men who tend to develop balanitis after sex should wash their penis after engaging in sexual activity.