The security of computers is at risk because of information leaking through their power consumption. Attackers can use advanced signal measurement and analysis to recover sensitive data from this side channel.To address this problem, this paper presents Maya, a simple and effective defense against power side channels. The idea is to use formal control to re-shape the power dissipated by a computer in an application-transparent manner—preventing attackers from learning any information about the applications that are running. With formal control, a controller can reliably keep power close to a desired target function even when runtime conditions change unpredictably. By selecting the target function intelligently, the controller can make power to follow any desired shape, appearing to carry activity information which, in reality, is unrelated to the application. Maya can be implemented in privileged software, firmware, or simple hardware. In this paper, we implement Maya on three machines using privileged threads only, and show its effectiveness and ease of deployment. Maya has already thwarted a newly-developed remote power attack.

Since computers increasingly execute in constrained environments, they are being equipped with controllers for resource management. However, the operation of modern computer systems is structured in multiple layers, such as the hardware, OS, and networking layers—each with its own resources. Managing such a system scalably and portably requires that we have a controller in each layer, and that the different controllers coordinate their operation. In addition, such controllers should not rely on heuristics, but be based on formal control theory. This paper presents a new approach to build coordinated multilayer formal controllers for computers. The approach uses Structured Singular Value (SSV) controllers from Robust Control Theory. Such controllers are especially suited for multilayer computer system control. Indeed, SSV controllers can read signals from other controllers to coordinate multilayer operation. In addition, they allow designers to specify the discrete values allowed in each input, and the desired bounds on output value deviations. Finally, they accept uncertainty guardbands, which incorporate the effects of interference between the controllers. We call this approach Yukta. To assess its effectiveness, we prototype it in an 8-core big. LITTLE board. We build a two-layer SSV controller, and show that it is very effective. Yukta reduces the ExD and the execution time of a set of applications by an average of 50% and 38%, respectively, over advanced heuristic-based coordinated controllers.

Multicores increasingly execute in constrained environments, and are being equipped with controllers for resource management. However, modern multicore systems are structured in multiple complex layers, such as the hardware, OS, and networking layers, each with its own resources. Managing such a system scalably and portably requires that we have a controller in each layer, and that the different controllers coordinate their operation. We present a novel methodology to build coordinated multilevel formal controllers in computing. We consider Robust Control Theory, which focuses on decision making in uncertain environments, and pick the popular Structured Singular Value (SSV) controller. This is the first work to utilize Robust Control Theory for compute resource management. Our contribution are: 1) Novel interdisciplinary application of SSV controllers from robust control theory for coordinating multilayer controllers in computers; and 2) A practical methodology for independent teams to design coordinating multilayer SSV controllers.