Protection domains in a single address space
US5845129A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 22, 1996 |
| Grant date | Dec 1, 1998 |
| Priority date | — |
| Expiry date | Mar 22, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F12/1491
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
Protection among threads executing in the same address space of a computer system is provided without using virtual memory techniques. This is achieved by grouping the threads into protection domains, each of the threads in a protection domain having the same rights to access memory as the other threads in that protection domain, so that each thread in a protection domain can access all the information available to the others. At least one protection domain, referred to herein as the "system" domain, which typically is the protection domain of the operating system and has unrestricted access to the entire memory, is predefined prior to execution of any threads. Prior to execution, the single address space is divided into non-overlapping pages. Each page has at least one access permission set for it. Only threads that belong to a protection domain having permission to access a page may do so. During operation, when a request to access memory is issued by an executing thread, it is determined whether or not the protection domain of the executing thread has permission to perform the requested type of access. If the protection domain of the executing thread is permitted to perform the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.