#ifndef STACK_RND_MASK
#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12))     /* 8MB of VA */
#endif

static unsigned long randomize_stack_top(unsigned long stack_top)
{
   unsigned int random_variable = 0;

   if ((current->flags & PF_RANDOMIZE) &&
       !(current->personality & ADDR_NO_RANDOMIZE)) {
       random_variable = get_random_int() & STACK_RND_MASK;
       random_variable <<= PAGE_SHIFT;
   }
}