/* syscall.c
 *
 * Simple system calls to printk and return. Hard coded into the kernel.
 * Has calls with return value (241) and return value with parameter (242)
 *
 */

/* kernel programming */
#ifndef LINUX
#define LINUX
#endif

#ifndef __KERNEL__
#define __KERNEL__
#endif

#include <linux/kernel.h>      /* for KERN_ALERT */

/* Prototypes */
asmlinkage void my_syscall(void);
asmlinkage int my_syscall_ret(void);
asmlinkage int my_syscall_parm(char *);

/*
 * My new system call 240
 */

asmlinkage void my_syscall(void)
{
  /* The following messages appear in /var/log/syslog */
  printk(KERN_ALERT "my_syscall: entering. \n");
  printk(KERN_ALERT "my_syscall: leaving. \n");
}

/*
 * My new system call 241 with return value
 */

asmlinkage int my_syscall_ret(void)
{
  /* The following messages appear in /var/log/syslog */
  printk(KERN_ALERT "my_syscall_ret: entering. \n");
  printk(KERN_ALERT "my_syscall_ret: leaving. \n");
  return 7;
}

/*
 * My new system call 242 with parameters and return value
 */

asmlinkage int my_syscall_parm(char * msg)
{
  /* The following messages appear in /var/log/syslog */
  printk(KERN_ALERT "my_syscall_parm: entering. \n");
  printk(KERN_ALERT "message from user: %s\n", msg);
  printk(KERN_ALERT "my_syscall_parm: leaving. \n");
  return 11;
}