🚀 go-pugleaf

Emmett Witchel from MIT will be giving a talk next Thursday
(the 10th) at 10:00am. He's interviewing for a position in
ECE, but would probably work with people in CS as well. Please
come to the talk if you're interested. There will also be an
informal lunch following the talk from 12:00-1:00 in 8th floor
conference rooms. I'll post information about the talk location

If you would like to sign up to talk to Emmett, either let me
know or contact carrol.kalafus@colorado.edu directly to arrange
a time on the 10th or 11th.

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Mondriaan Memory Protection

Modern computer systems implement memory protection as part of virtual
address translation, limiting it to the granularity of whole pages,
which have grown to be 4KB or more.  System developers tolerate this
antique form of memory protection because previous attempts at
fine-grained memory protection, for example capabilities or
segmentation, have proven ungainly to program and difficult to
engineer for high performance.  Efficient fine-grained memory
protection would remove the need for the cumbersome workarounds that
appear regularly in research conferences, and would enable a new class
of robust extensible software systems.

This talk presents a new solution for fine-grained memory protection
called Mondriaan Memory Protection (MMP).  MMP supports multiple
protection domains sharing the same address space.  Each domain has
its own permissions table which supports (32-bit) word-level
protection for arbitrary runs of words at any word boundary.  Space
overheads are reduced with a compressed permissions table structure,
and run-time overheads are reduced by using two-levels of hardware
permissions caching.  Even under heavy use, space overhead is less
than 9% and memory reference overhead is less than 8%.  MMP works with
linear addresses and so is compatible with existing instruction sets
and operating systems.

The talk will cover the obvious and non-obvious data structures that
are required for MMP's good performance.  The talk will also discuss
extensions to MMP, and present preliminary data on using MMP to
enforce module boundaries in the Linux kernel.