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14.
03.
2008
Avoiding Timing Channels in Fixed-Priority Schedulers
Marcus Völp
TU Dresden
A practically feasible modification to fixed-priority schedulers
allows to avoid timing channels despite threads having access to
precise clocks. This modification is rather simple: we compute at
admission time a static predicate that states whether a thread may
possibly leak information; if such a thread blocks we switch to the
idle thread instead. We describe the modified scheduler, provide a
mechanical PVS-based proof of noninterference and show how common
admission algorithms can be reused to give real-time guarantees for
this modified scheduler. While providing similar isolation
guarantees, our approach outperforms time-partitioning schedulers in
terms of achieved real-time guarantees.
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