+#ifndef STACK_RND_MASK
+#define STACK_RND_MASK (0x7ff >> (PAGE_SHIFT - 12)) /* 8MB of VA */
+#endif
+
+unsigned long randomize_stack_top(unsigned long stack_top)
+{
+ unsigned long random_variable = 0;
+
+ if (current->flags & PF_RANDOMIZE) {
+ random_variable = get_random_long();
+ random_variable &= STACK_RND_MASK;
+ random_variable <<= PAGE_SHIFT;
+ }
+#ifdef CONFIG_STACK_GROWSUP
+ return PAGE_ALIGN(stack_top) + random_variable;
+#else
+ return PAGE_ALIGN(stack_top) - random_variable;
+#endif
+}
+