E. Christopher Lewis

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Commodity operating systems entrusted with securing sensitive data are remarkably large and complex, and consequently, frequently prone to compromise. To address this limitation, we introduce a virtual-machine-based system called Overshadow that protects the privacy and integrity of application data, even in the event of a total OScompromise. Overshadow(More)
<b>Dynamic Instruction Stream Editing (DISE)</b> is a cooperative software-hardware scheme for efficiently adding customization functionality---e.g, safety/security checking, profiling, dynamic code decompression, and dynamic optimization---to an application. In DISE, application customization functions (ACFs) are formulated as rules for macro-expanding(More)
It is generally acknowledged that developing correct multi-threaded codes is difficult, because threads may interact with each other in unpredictable ways. The goal of this work is to discover common multi-threaded programming pitfalls, the knowledge of which will be useful in instructing new programmers and in developing tools to aid in multi-threaded(More)
Hardware transactional memory has great potential to simplify the creation ofcorrect and efficient multithreaded programs, allowing programmers to exploitmore effectively the soon-to-be-ubiquitous multi-core designs. Several recentproposals have extended the original bounded transactional memory to unboundedtransactional memory, a crucial step toward(More)
The goal of producing architecture-independent parallel programs is complicated by the competing need for high performance. The ZPL programming language achieves both goals by building upon an abstract parallel machine and by providing programming constructs that allow the programmer to " see " this underlying machine. This paper describes ZPL and provides(More)
Code compression coupled with dynamic decompression is an important technique for both embedded and general-purpose microprocessors. <i>Post-fetch decompression</i>, in which decompression is performed after the compressed instructions have been fetched, allows the instruction cache to store compressed code but requires a highly efficient decompression(More)
Array languages such as Fortran 90, HPF and ZPL have many benefits in simplifying array-based computations and expressing data parallelism. However, they can suffer large performance penalties because they introduce intermediate arrays---both at the source level and during the compilation process---which increase memory usage and pollute the cache. Most(More)
Stack-smashing by buffer overflow is a common tactic used by viruses and worms to crash or hijack systems. Exploiting a bounds-unchecked copy into a stack buffer, an attacker can---by supplying a specially-crafted and unexpectedly long input---overwrite a stored return address and trigger the execution of code of her choosing. In this paper, we propose to(More)
Most array languages, including Fortran 90, Matlab, and APL, provide support for referencing arrays by extending the traditional array subscripting construct found in scalar languages. We present an alternative to subscripting that exploits the concept of <i>regions</i>---an index set representation that can be named, manipulated with high-level operators,(More)
ZPL is a parallel array language designed for high performance scientific and engineering computations. Unlike other parallel languages, ZPL is founded on a machine model (the CTA) that accurately abstracts contemporary MIMD parallel computers. This makes it possible to correlate ZPL programs with machine behavior. As a result, programmers can reason about(More)