Porting and Generalizing Dynamic Privilege in Linux
summary
Project ports a Dynamic Privilege mechanism from x86_64 to ARM64 by adding a K_elevate syscall and a task_struct flag to track elevation, with a working ARM64 implementation and lessons for RISC‑V. x86 needs an alternate exit path because sysenter/sysret (segment selector behavior) forces privilege drops; ARM uses PSTATE and the saved program status register to flip mode between SVC and return. A permissions fault on ARM leads to a pragmatic fix: a dynamic single-page PT mapping option passed to the syscall to make just the return page executable for elevated code.
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chapters (11)
- 0:00Introduction
- 1:49What is Dynamic Privilege
- 3:13Motivations
- 5:20System call interface
- 7:50Kernel changes overview
- 8:10x86 challenges
- 10:39ARM flexibility
- 13:12Privileged memory access
- 16:02RISC-V future work
- 17:28Process caching
- 18:33Q&A
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