Re: Help !! calling function in module from a user program

[Srinivas Chinta <chintasrinivas_tech@yahoo.com>]

[-- Attachment #1: Type: text/plain, Size: 1264 bytes --]

Hi,
One way of doing this is , by hooking up your function
inside the module as a system call.
Here i'm sending two files, module.c and user_space.c.
first do "insmod module.o" and then run
"./user_space".
As i'm also a newbee, i'm not aware of the
disadvantages of this approach.

thanks,
Srinivasu Chinta.

--- Sudharsan Vijayaraghavan <svijayar@cisco.com>
wrote:
> Hi,
> 
> Am a new bee to linux internals.
> I am trying to make a simple program witch will call
> a function from a 
> module. I made a module compiled it and INSMOD-it
> into kernel, that works 
> fine. I would like to call from my user program a
> function defined in my 
> kernel module.
> 
> Please suggest any method thro' which this could be
> accomplished.
> The only way i did it was by running my new module
> as insmod mymodule.o and 
> get my job done.
> 
> Thanks,
> Sudharsan.
> 
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[-- Attachment #2: module.c --]
[-- Type: text/plain, Size: 463 bytes --]

#define MODULE
#define __KERNEL__
#include <linux/module.h>
#include <linux/kernel.h>

extern void *sys_call_table[];
void * org_func;

static void my_func()
{
        printk("Executing my_func...!");
}
int init_module(void)
{
        printk("init_module ...!");
        org_func = sys_call_table[250];
        sys_call_table[250] = my_func;
        return 0;
}
void cleanup_module()
{
        sys_call_table[250] = org_func;
        printk("cleaning up...!");
}

[-- Attachment #3: user_space.c --]
[-- Type: text/plain, Size: 145 bytes --]

#include <stdio.h>
#include <errno.h>
#include <asm/unistd.h>
#define __NR_my_func 250

_syscall0(void, my_func);

main()
{
        my_func();
}