如何在linux模块中使用systemcalls

I attempted to use systemcalls such as sys_sendto when programming a kernel module. But the compiler warned me that the symbol 'sys_sendto' is undefined. I'm sure I have inculded the header file syscalls.h, so please help me and thank you. P.S: My linux version is 2.6.32I attempted to use systemcalls such as sys_send