How to determine whether an address in the field of system DLL

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Win32

DLL

I HOOK an API, I would like to determine if when is called return address is on the user's area, what I think is, if not on the field of system DLL will think he is on the user's area, the question now is, how to determine whether the address is on the areas of system DLL

ps:I can't speak English, I use BING translation, so if you don't understand it doesn't matter