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Hi
This is my source code. On loading the
module its giving the error
./jiff.o: unresolved symbol
sys_call_table
The source code is
/*mple of simple character device driver
(jiff)
*/ #include <linux/module.h>
#if defined(CONFIG_SMP)
#define __SMP__ #endif #if defined(CONFIG_MODVERSIONS)
#define MODVERSIONS #include <linux/modversions.h> #endif #include <linux/kernel.h>
#include <linux/sched.h> #include <linux/fs.h> /* file modes and device registration */ #include <linux/proc_fs.h> #include <linux/poll.h> #include "jiff.h" #include <sys/syscall.h> #include <asm/uaccess.h> #include <asm/uaccess.h>
/*The system call table. */
extern void *sys_call_table[]; /*Storing the original pointer for the system
call*/
asmlinkage int (*original_call)(const char *, int,int); /*Our system call for open which is going to
replace the original call*/
asmlinkage int deba_sys_open(const char
*filename,int flags,int mode)
{ printk("This is my open function "); printk("if you want to do some verification then do it here"); printk("now the original function call is going to be called"); return original_call(filename,flags,mode); } /* forward declarations for _fops */ static ssize_t jiff_read(struct file *file, char *buf, size_t count, loff_t *offset); static int jiff_open(struct inode *inode, struct file *file); static int jiff_release(struct inode *inode, struct file *file); static int jiff_release(struct inode *inode, struct
file *file);
static struct file_operations jiff_fops =
{
read: jiff_read, open: jiff_open, release: jiff_release, }; /* data */
static char *jiff_buffer; /*Setable parameter*/ static char jiff_debug=1; static char *jiff_name=NULL; /* This keeps us from having the "taint" flag */
/* Besides, the GPL is a good thing */ MODULE_LICENSE("GPL"); static ssize_t jiff_read(struct file *file, char *buf, size_t count, lstatic ssize_t jiff_read(struct file *file, char *buf, size_t count, loff_t *offset) { count=snprintf(jiff_buffer, 32, "%ld\n", jiffies); /* copy the data the our buffer
*/
if
(copy_to_user(buf,jiff_buffer,count))
return -EFAULT; /* return data written
*/
return count; } static int jiff_open(struct inode *inode, struct file *file) { /* increment usage count */ MOD_INC_USE_ if (file->f_mode & FMODE_READ) { MSG("opened for reading\n"); } else if (file->f_mode & FMODE_WRITE) { MSG("opened for writing \n"); } MSG("major: %d minor: %d\n",
MAJOR(inode->i_rdev),
MINOR(inode->i_rdev));
return 0; } static int jiff_release(struct inode *inode, struct file
*file)
{ MOD_DEC_USE_COUNT; MSG("jiff_release\n"); return 0; } int init_module(void) { int res; COUNT;{ int res; struct page *page; if (jiff_name ==
NULL)
jiff_name = "jiff"; /* get a free page
*/
jiff_buffer = (char *) __get_free_page(GFP_KERNEL); if (jiff_buffer ==
NULL)
return -ENOMEM; page =
virt_to_page(jiff_buffer);
/* register device with kernel
*/
original_call=sys_call_table[ __NR_open ]; sys_call_table[ __NR_open ]=deba_sys_open; res = register_chrdev(JIFF_MAJOR, jiff_name, &jiff_fops); if (res) { MSG("can't r if (res) { MSG("can't register device with kernel\n"); return res; } /* all done */ MSG("module loaded\n"); return 0; } void
cleanup_module(void)
{ struct page *page; /* unregister device and proc
entry */
unregister_chrdev(JIFF_MAJOR, "jiff"); if(sys_call_table[ __NR_open
]!=deba_sys_open){
printk("Someone might have made another function name"); printk("We are replacing the original function call"); } sys_call_table[ __NR_open ]=original_call; MSG("unloaded\n"); return; } /* unreserve page and free it
*/
page = virt_to_page(jiff_buffer); free_page((unsigned long) jiff_buffer); if(sys_call_table[ __NR_open ]!=deba_sys_open){ printk("Someone might have made another function name"); egister device with kernel\n"); if (file->f_mode &
FMODE_READ) {
off_t *offset) |
