Here's v3. It fixes the "dazed and confused" issue, I hope. It's also
probably a good general attack surface reduction, and it replaces some
scary code with IMO less scary code.
Also, servers and embedded systems should probably turn off modify_ldt.
This makes that possible.
Xen people, can you take a look at this?
Willy and Kees: I left the config option alone. The -tiny people will
like it, and we can always add a sysctl of some sort later.
Changes from v3:
- Hopefully fixed Xen.
- Fixed 32-bit test case on 32-bit native kernel.