How to identify processes running in user mode and kernel mode
 

I am somewhat new to linux and I am finding difficulty to understand some differences. Here is my question: I would like to know the way to find the processes which is running in user mode and which is running in kernel mode. Is there any command to execute for the above? I am confused with the user mode and kernel mode context most of the times. Please help me.

The details of invoking kernel call directly are outdated as it references kernel 2.4, but the diagram here gives you a general idea of the general flow:

http://ar.linux.it/docs/ksys/ksys.html

Google 'kernel space' for more info.