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Unformatted text preview: Process 2: 0 PP 8 VP 1
VP 2 ... ... N-‐1 Address TranslaMon M-‐1 (e.g., read-‐only library code) University of Washington VM for ProtecMon and Sharing ¢ The mapping of VPs to PPs provides a simple mechanism for protecKng memory and for sharing memory btw. processes § Sharing: just map virtual pages in separate address spaces to the same physical page (here: PP 6) § ProtecKon: process simply can’t access physical pages it doesn’t have a mapping for (here: Process 2 can’t access PP 2) Address 0 0 Physical Virtual translaKon
Address Address VP 1
Space for Process 1: VP 2 PP 2 ... Space (DRAM) N-‐1 PP 6 Virtual Address Space for Process 2: 0 PP 8 VP 1
VP 2 ... ... N-‐1 Address TranslaMon M-‐1 (e.g., read-‐only library code) University of Washington Memory ProtecMon Within a Single Process ¢
¢ Extend PTEs with permission bits MMU checks these permission bits on every memory access § If violated, raises excepKon and OS sends SIGSEGV signal to process Process...
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This document was uploaded on 04/04/2014.
- Fall '09