Memory stack for ring protection architecture

Claim 2

In a multiprocessing/multiprogramming computer system having a ring architecture comprised of at least four rings numbered 0-3 with the innermost ring being assigned an identity of 0 and the outermost ring being assigned an identity of 3, and with the innermost ring being the highest level of privilege, a plurality of processors for executing procedures thereon, a software operating system for supervising/scheduling the execution of the procedures, each procedure and the software operating system having a predetermined level of privilege, each of said procedures for executing at its predetermined level of privilege, a software/firmware mechanism for permitting a procedure executing at a lower level of privilege to execute at a higher level of privilege (i.e., inward call to a lower ring number) comprising: (a) a call instruction implemented partly in firmware and partly in software; (b) a stack mechanism for storing hardware managed control information in a control frame and a software controlled data in a data frame.

Claim 3

The computer system as recited in Claim 1 wherein the stack mechanism is comprised of stacks in separate stack segments, ring 0 stack segment to ring 3 stack segment.

Claim 4

The computer system as recited in Claim 2 wherein the ring 0 stack segment is a hardwired stack segment utilized for operating system (OS) procedures which cannot tolerate page faults.

Claim 5

The computer system as recited in Claim 3 wherein the ring 1-3 stack segments are non-wired ring stack segments (one per ring) supporting path control, and data storage utilized by user procedures.

Claim 6

5 . The computer system as recited in Claim 4 including first address means for providing an address for a non-wired stack segment.

Claim 7

The apparatus as recited in Claim 5 including second address means for providing an address for a wired stack segment.

Claim 8

7 . The apparatus as recited in Claim 6 wherein the second means stores a partial stack base address and a ring number which are concatenated to provide a ring 0 segment stack base address.

Claim 9

In a multiprocessing/multiprogramming computer system having a ring architecture comprised of at least four rings numbered 0-3 with the innermost ring being assigned an identity of 0 and the outermost ring being assigned an identity of 3, and with the innermost ring being the highest level of privilege, a plurality of processors for executing procedures thereon, firmware instruction and software instruction, a software operating system for supervising/scheduling the execution of the procedures, each procedure and the software operating system having a predetermined level of privilege, each of said procedures for executing at its predetermined level of privilege, a method for permitting a procedure executing at a lower level of privilege to execute at a higher level of privilege (i.e., inward call to a lower ring number) comprising: (a) changing the level of privilege of a procedure by utilizing a firmware instruction to perform a portion of the change and utilizing a software instruction to perform another portion of the change; and (b) providing a stack mechanism for storing hardware managed control information in a control frame and a software controlled data in a data frame.

Claim 10

In a multiprocessing/multiprogramming computer system having a ring architecture comprised of at least four rings numbered 0-3 with the innermost ring being assigned an identity of 0 and the outermost ring being assigned an identity of 3, and with the innermost ring being the highest level of privilege, a plurality of processors for executing procedures thereon, firmware instruction and software instruction, a software operating system for supervising/scheduling the execution of the procedures, each procedure and the software operating system having a predetermined level of privilege, each of said procedures for executing at its predetermined level of privilege, a method for permitting a procedure executing at a lower level of privilege to execute at a higher level of privilege (i.e., inward call to a lower ring number) comprising: (a) changing the level of privilege of a procedure by utilizing a firmware instruction to perform a portion of the change and utilizing a software instruction to perform another portion of the change; and (b) providing a stack mechanism for storing hardware managed control information in a control frame and a software controlled data in a data frame.