Kernel APIs or using APIs in the kernel

I'd like to know if and how I can access API calls inside the kernel. I need them to preform several integrity checks on a program of mine running in user mode. But I don't know how I can access the APIs and function开发者_开发技巧s required to do so.

How do I obtain the process id of my user mode process? And how do I access all its memory to preform the check?

PS: I'm on a Windows XP machine.

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Yes, you can do that by creating a kernel mode driver and then communicating with your user mode process from the kernel space. You can refer this document for detailed information.