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1. Going beyond the Limits of SFI: Flexible and Secure Hardware-Assisted In-Process Isolation with HFI

   https://doi.org/10.1145/3582016.3582023  

   Narayan, Shravan; Garfinkel, Tal; Taram, Mohammadkazem; Rudek, Joey; Moghimi, Daniel; Johnson, Evan; Fallin, Chris; Vahldiek-Oberwagner, Anjo; LeMay, Michael; Sahita, Ravi; et al (March 2023, Proceedings of the 28th ACM International Conference on Architectural Support for Programming Languages and Operating Systems, Volume 3)

   We introduce Hardware-assisted Fault Isolation (HFI), a simple extension to existing processors to support secure, flexible, and efficient in-process isolation. HFI addresses the limitations of existing software-based isolation (SFI) systems including: runtime overheads, limited scalability, vulnerability to Spectre attacks, and limited compatibility with existing code. HFI can seamlessly integrate with current SFI systems (e.g., WebAssembly), or directly sandbox unmodi!ed native binaries. To ease adoption, HFI relies only on incremental changes to the data and control path of existing high-performance processors. We evaluate HFI for x86-64 using the gem5 simulator and compiler-based emulation on a mix of real and synthetic workloads. 

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2. Online Rotor Fault Detection and Isolation for Vertical Takeoff and Landing Vehicles

   https://doi.org/10.1109/IROS58592.2024.10802021  

   Lian, Jiaqi; Gandhi, Neeraj; Wang, Yifan; Xuan_Phan, Linh Thi (October 2024, IEEE)

   Vertical take-off and landing (VTOL) vehicles are becoming increasingly popular for real-world transport; but, as with any vehicle, guaranteeing safety is both extremely critical and highly challenging due to issues like rotor faults. Existing fault detection and isolation (FDI) techniques usually focus on multirotor systems or fixed wing systems, rather than the hybrid VTOLs. Since VTOLs have both rotors and ailerons, a fault in a rotor may be masked by the (correctly working) ailerons, making it much more difficult to detect faults. However, this masking only works when ailersons are used (e.g., during cruising), leaving the takeoff and landing vulnerable to crashes. This paper presents an online rotor fault detection and isolation (FDI) method for VTOLs. The approach uses pose analysis and aileron command data to quickly and accurately identify the faulty rotor and to compute the severity of the fault. Our method works for hard-to-detect fault scenarios, such as small-severity faults that are masked during cruise flight but not during vertical motion. We evaluated our technique in a SITL PX4 simulation of a modified Deltaquad QuadPlane. The results show that our FDI technique can quickly detect and isolate faults in real time (within 1s-2.5s) and achieve high isolation success rate (91.67%) across six rotors, and that it can estimate the severity of faults to within 2%. When applying a simple recovery process post-isolation, the system consistently achieved safe landing. 

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3. The Omnivisor: A Real-Time Static Partitioning Hypervisor Extension for Heterogeneous Core Virtualization over MPSoCs

   https://doi.org/10.4230/LIPIcs.ECRTS.2024.7  

   Ottaviano, Daniele; Ciraolo, Francesco; Mancuso, Renato; Cinque, Marcello (July 2024, Schloss Dagstuhl – Leibniz-Zentrum für Informatik)

   Pellizzoni, Rodolfo (Ed.)

   Following the needs of industrial applications, virtualization has emerged as one of the most effective approaches for the consolidation of mixed-criticality systems while meeting tight constraints in terms of space, weight, power, and cost (SWaP-C). In embedded platforms with homogeneous processors, a wealth of works have proposed designs and techniques to enforce spatio-temporal isolation by leveraging well-understood virtualization support. Unfortunately, achieving the same goal on heterogeneous MultiProcessor Systems-on-Chip (MPSoCs) has been largely overlooked. Modern hypervisors are designed to operate exclusively on main cores, with little or no consideration given to other co-processors within the system, such as small microcontroller-level CPUs or soft-cores deployed on programmable logic (FPGA). Typically, hypervisors consider co-processors as I/O devices allocated to virtual machines that run on primary cores, yielding full control and responsibility over them. Nevertheless, inadequate management of these resources can lead to spatio-temporal isolation issues within the system. In this paper, we propose the Omnivisor model as a paradigm for the holistic management of heterogeneous platforms. The model generalizes the features of real-time static partitioning hypervisors to enable the execution of virtual machines on processors with different Instruction Set Architectures (ISAs) within the same MPSoC. Moreover, the Omnivisor ensures temporal and spatial isolation between virtual machines by integrating and leveraging a variety of hardware and software protection mechanisms. The presented approach not only expands the scope of virtualization in MPSoCs but also enhances the overall system reliability and real-time performance for mixed-criticality applications. A full open-source reference implementation of the Omnivisor based on the Jailhouse hypervisor is provided, targeting ARM real-time processing units and RISC-V soft-cores on FPGA. Experimental results on real hardware show the benefits of the solution, including enabling the seamless launch of virtual machines on different ISAs and extending spatial/temporal isolation to heterogenous cores with enhanced regulation policies. 

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4. RedLeaf: Isolation and Communication in a Safe Operating System

   Narayanan, Vikram; Huang, Tianjiao; Detweiler, David; Appel, Dan; Li, Zhaofeng; Zellweger, Gerd; Burtsev, Anton (November 2020, USENIX Symposium on Operating Systems Design and Implementation (OSDI))

   null (Ed.)

   RedLeaf is a new operating system developed from scratch in Rust to explore the impact of language safety on operating system organization. In contrast to commodity systems, RedLeaf does not rely on hardware address spaces for isolation and instead uses only type and memory safety of the Rust language. Departure from costly hardware isolation mechanisms allows us to explore the design space of systems that embrace lightweight fine-grained isolation. We develop anew abstraction of a lightweight language-based isolation domain that provides a unit of information hiding and fault isolation. Domains can be dynamically loaded and cleanly terminated, i.e., errors in one domain do not affect the execution of other domains. Building on RedLeaf isolation mechanisms, we demonstrate the possibility to implement end-to-end zero-copy, fault isolation, and transparent recovery of device drivers. To evaluate the practicality of RedLeaf abstractions, we implement Rv6, a POSIX-subset operating system as a collection of RedLeaf domains. Finally, to demonstrate that Rust and fine-grained isolation are practical—we develop efficient versions of a 10Gbps Intel ixgbe network and NVMe solid-state disk device drivers that match the performance of the fastest DPDK and SPDK equivalents. 

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5. The co-occurrence of water insecurity and food insecurity among Daasanach pastoralists in northern Kenya

   https://doi.org/10.1017/S1368980022001689  

   Bethancourt, Hilary J; Swanson, Zane S; Nzunza, Rosemary; Young, Sera L; Lomeiku, Luke; Douglass, Matthew J; Braun, David R; Ndiema, Emmanuel K; Pontzer, Herman; Rosinger, Asher Yoel (March 2023, Public Health Nutrition)

   Abstract Objective: Water plays a critical role in the production of food and preparation of nutritious meals, yet few studies have examined the relationship between water and food insecurity. The primary objective of this study, therefore, was to examine how experiences of household water insecurity (HWI) relate to experiences of household food insecurity (HFI) among a pastoralist population living in an arid, water-stressed region of northern Kenya. Design: We implemented the twelve-item Household Water Insecurity Experiences (HWISE, range 0–36) Scale and the nine-item Household Food Insecurity Access Scale (HFIAS, range 0–27) in a cross-sectional survey to measure HWI and HFI, respectively. Data on socio-demographic characteristics and intake of meat and dairy in the prior week were collected as covariates of interest. Setting: Northern Kenya, June–July 2019. Participants: Daasanach pastoralist households ( n 136) from seven communities. Results: In the prior 4 weeks, 93·4 % and 98·5 % of households had experienced moderate-to-severe HWI and HFI, respectively. Multiple linear regression analyses indicated a strong association between HWI and HFI. Each point higher HWISE score was associated with a 0·44-point (95 % CI: 0·22, 0·66, P = 0·003) higher HFIAS score adjusting for socio-economic status and other covariates. Conclusions: These findings demonstrate high prevalence and co-occurrence of HWI and HFI among Daasanach pastoralists in northern Kenya. This study highlights the need to address HWI and HFI simultaneously when developing policies and interventions to improve the nutritional well-being of populations whose subsistence is closely tied to water availability and access. 

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