Previously virt_to_phys/phys_to_virt macros were used such that they did a
blind offset translation for creating a pager internal virtual address for
user mappings.
This is now changed such that a properly bookkeeped virtual address pool is
used which will avoid any clashes on the virtual space.
- Fixed do_mmap() so that it returns mapped address, and various bugs.
- A child seems to fork with new setup, but with incorrect return value.
Need to use and test exregs() for fork + clone.
- Shmat searches an unmapped area if input arg is invalid, do_mmap()
should do this.
