11/02

informative system calls

• kernel/sys.c
  • sethostname, gethostname
  • about copy_to_user/copy_from_user
• kernel/hrtimer.c
  • nanosleep
  • about timespec
• kernel/posix-timers.c
  • clock_gettime
  • about timespec
• kernel/module.c
  • delete_module
  • about strncpy_from_user
• kernel/printk.c
  • about __LOG_BUF_LEN/access_ok

testing new_debug syscall

• windell57:i386 s0711489$ make -j2

  Kernel: arch/x86/boot/bzImage is ready  (#3)
  

• s0711489@ubuntu-lucid:~$ sudo /mnt/hgfs/tools/install.sh
• s0711489@ubuntu-lucid:~$ sudo reboot

• s0711489@ubuntu-lucid:~$ cat > new_debug-sys.c
• s0711489@ubuntu-lucid:~$ gcc -I /lib/modules/2.6.35.14/build/arch/x86/include/ new_debug-sys.c

• s0711489@ubuntu-lucid:~$ ./a.out

  new_debug()
  

• s0711489@ubuntu-lucid:~$ dmesg | tail -n 2

  [    6.833440] dhclient3 used greatest stack depth: 5560 bytes left
  [  579.378377] new_debug()
  

• s0711489@ubuntu-lucid:~$ ./a.out hoge fuga piyo

  [-570566464.-1216585740] hoge
  [0.000000000] fuga
  [0.000000000] piyo
  

• s0711489@ubuntu-lucid:~$ dmesg | tail -n 5

  [    6.833440] dhclient3 used greatest stack depth: 5560 bytes left
  [  579.378377] new_debug()
  [  596.785236] hoge
  [  596.785274] fuga
  [  596.785282] piyo
  

maybe useful

• ​http://hira-consulting.com/wiki/index.php?linux2.6%2Farch%2Fi386%2Flib%2Fusercopy.c
• ​http://hira-consulting.com/wiki/?linux2.6%2Finclude%2Flinux%2Ferr.h
• IS_ERR_OR_NULL
• __LOG_BUF_LEN

• ​https://www.codeblog.org/blog/gniibe/20060323.html
• ​get_user/put_user, set_fs のまとめ
• ​http://www.ibm.com/developerworks/jp/linux/library/l-system-calls/ の「copy_to_user」の定義が変

  unsigned long copy_from_user( void *to, const void __user *from, unsigned long n );
  unsigned long copy_to_user( void *to, const void __user *from, unsigned long n );
  

  • 以下が正しい

    unsigned long copy_from_user( void *to, const void __user *from, unsigned long n );
    unsigned long copy_to_user( void __user *to, const void *from, unsigned long n );
    

11/04

• define as static char __log_buf[__LOG_BUF_LEN] in printk.c
• sys_clock_gettime uses copy_to_user in its code