System call from Kernel

[Hitendra Upadhyay]

Hi Everyone,
I have written a kernel module in which i need to call system calls.
Actually my requirement is to shutdown the system whenever i get a signal.
But the system ("shutdown") doesn't work in kernel module.
I 've heard that if we use system_call_table and system_call then we can. But not getting any link.
Please help.....

[alex1983-0112]

Hi Hitendra,

So we have 7 macroses in linux kernel named as _syscal0 - _syscall6. The number in macros name assume parameters count in system call. Firsts two parameters in
_syscall0-6 are returning value and system call name. So if we want to use system call without parameters(such as fork) we use _syscall0, with 1 param - _syscall1 and etc. Next pair of parameters assume getting type and variable.
For example for fork() system call:

_syscall0(int , fork)

For exit:

_syscall1(int, exit, int, exit_code)

In u case (shutdown):


_syscall1(void, system, const char*, cmd)

void my_shutdown(const char *cmd) {
system(cmd);
}


Hope this help.