In a data/information processing system, a nested privilege protection is
employed to protect the system when executing instructions. A first
privilege protection having at least two privilege levels is enforced.
Additionally, a second privilege protection having at least two
sub-privilege levels is further enforced for at least one privilege level
of the first privilege protection to further differentiate the privileges
otherwise afforded. In one embodiment, core system services, programming
language runtime support and application programs are afforded the same
privilege level of the first privilege protection, and the different types
of programs are afforded different sub-privilege levels of the second
privilege protection to differentiate the privileges afforded by the first
privilege protection. In one embodiment, the differential sub-privilege
level protection is further extended to application programs of different
sources, making the system particularly suitable for networked
applications, such as accessing web servers on the Internet. In one
embodiment, the first privilege protection is hardware facilitated, while
the second privilege protection is software facilitated.
