ring0 priviledged actions

kernel_module/ring0.c

@@ -0,0 +1,33 @@
+/*
+This illustrates operations which are only possible in ring 0.
+https://stackoverflow.com/questions/7415515/how-to-access-the-control-registers-cr0-cr2-cr3-from-a-program-getting-segmenta/7419306#7419306
+
+It only works for x86_64.
+
+Then try to run this on userland and see the process be killed:
+
+    /ring0.out
+*/
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include "ring0.h"
+
+static int myinit(void)
+{
+#if defined(__x86_64__) || defined(__i386__)
+	Ring0Regs ring0_regs;
+	ring0_get_control_regs(&ring0_regs);
+	pr_info("cr0 = 0x%8.8llX\n", (unsigned long long)ring0_regs.cr0);
+	pr_info("cr2 = 0x%8.8llX\n", (unsigned long long)ring0_regs.cr2);
+	pr_info("cr3 = 0x%8.8llX\n", (unsigned long long)ring0_regs.cr3);
+#endif
+    return 0;
+}
+
+static void myexit(void) {}
+
+module_init(myinit)
+module_exit(myexit)
+MODULE_LICENSE("GPL");