[$] KAISER: hiding the kernel from user space

Since the beginning, Linux has mapped the kernel's memory into the addressspace of every running process. There are solid performance reasons fordoing this, and the processor's memory-management unit can ordinarily betrusted to prevent user space from accessing that memory. More recently,though, some more subtle security issues related to this mapping have cometo light, leading to the rapid development of a new patch set that ends thislongstanding practice for the x86 architecture.