Hardware Support for Safety-Critical Java Scope Checks

Phone +45 4525 3351 compute@compute.dtu.dk www.compute.dtu.dk IMM-PhD-2014-340 Summary (English) Safety-critical systems are real-time systems whose failure can have severe or catastrophic consequences, possibly endangering human life. Many safety-critical systems incorporate embedded computers used to control different tasks. Software running on safety-critical systems needs to be certified before its deployment and the most time-consuming step of this process is the testing and verification phase. Due to the increasing complexity in safety-critical systems there is a need for new technologies that can facilitate testing and verification activities.The safety-critical specification for Java aims at providing a reduced set of the Java programming language that can be used for systems that need to be certified at the highest levels of criticality. Safety-critical Java (SCJ) restricts how a developer can structure an application by providing a specific programming model and by restricting the set of methods and libraries that can be used. Furthermore, its memory model do not use a garbage-collected heap but scoped memories.In this thesis we examine the use of the SCJ specification through an implementation in a time-predictable, FPGA-based Java processor. The specification is now in a mature state and with our implementation we have proved its feasibility in an embedded platform. Moreover, we have explored how simple hardware extensions can reduce the execution time of time-critical operations required by the SCJ specification.The scoped memory model used in SCJ is perhaps one of its most difficult features to use correctly. Therefore, in this work we have also studied practical aspects of its usage by developing scoped memory use patterns and reusable libraries aiming at facilitating the development of complex software systems.ii Summary (Danish)Sikkerhedskritiske systemer er realtidssystemer. Hvis sådanne systemer fejler, kan det have alvorlige eller katastrofale konsekvenser, muligvis livsfarlige konsekvenser. Mange sikkerhedskritiske systemer inkorporerer embeddede computere, som bruges til at kontrollere forskellige opgaver. Software, som kører på sikkerhedskritiske systemer, skal certificeres, før softwaren udrulles, og det mest tidskraevende skridt i denne proces er test-og verifikationsfasen. På grund af den stigende kompleksitet i sikkerhedskritiske systemer er der behov for nye teknologier til at facilitere test-og verifikationsaktiviteter.Den sikkerhedskritiske specifikation for Java har til formål at levere en reduceret udgave af Java-programmeringssproget, som kan bruges til systemer, der skal kunne certificeres på de højeste kritikalitetsniveauer. Safety Critical Java (SCJ) begraenser, hvordan en udvikler kan strukturere en applikation, ved at levere en specifik programmeringsmodel og ved at begraense de metoder og biblioteker, som kan anvendes. Derudover benytter hukommelsesmodellen i SCJ ikke en heap, der er garbage-collected, men afgraensede hukommelser.I denne afhandling undersøger vi brugen a...

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“…Hardware Support for Safety-Critical Java Scope Checks [103]. In Section 3.6 we describe the facilities to interact with external devices, i.e.…”

Section: Safety-critical Java On An Embedded Java Processormentioning

confidence: 99%

Safety‐critical Java for embedded systems

Schoeberl

Dalsgaard

Hansen

et al. 2016

Concurrency and Computation

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“…One can assign level 0 for immortal memory, level 1 for the initial mission memory, level 2 for the initial private memory, and so on. These levels, statically assigned to each memory area, can be used to simplify the reference assignment checks [13]. A reference field of an object at level n may only point to an object allocated at level m ≤ n. Static fields are allocated in immortal memory and therefore, their level is 0.…”

Section: A Scope Memoriesmentioning

confidence: 99%

An Evaluation of Safety-Critical Java on a Java Processor

Rios¹,

Schoeberl²

2014

2014 IEEE 17th International Symposium on Object/Component/Service-Oriented Real-Time Distributed Computing

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Abstract-The safety-critical Java (SCJ) specification provides a restricted set of the Java language intended for applications that require certification. In order to test the specification, implementations are emerging and the need to evaluate those implementations in a systematic way is becoming important.In this paper we evaluate our SCJ implementation which is based on the Java Optimized Processor JOP and we measure different performance and timeliness criteria relevant to hard real-time systems. Our implementation targets Level 0 and Level 1 of the specification and to test it we use a series of micro benchmarks, an application-based benchmark, and a reduced set of a SCJ technology compatibility kit. We evaluate the accuracy of periods, linear-time memory allocation, aperiodic event handling, dispatch latency for interrupts, context switch preemption latency, and synchronization.

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“…A hardware implementation of the scope checking was presented by Rios et al [31], showing that such checking can be done very efficiently for SCJ in hardware due to the simple stack structure of the memory scopes in use.…”

Section: Memory Safetymentioning

confidence: 99%

Certifiable Java for Embedded Systems

Schoeberl

Dalsgaard

Hansen

et al. 2014

Proceedings of the 12th International Workshop on Java Technologies for Real-Time and Embedded Systems

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The Certifiable Java for Embedded Systems (CJ4ES) project aimed to develop a prototype development environment and platform for safety-critical software for embedded applications. There are three core constituents: A profile of the Java programming language that is tailored for safety-critical applications, a predictable Java processor built with FPGA technology, and an Eclipse based application development environment that binds the profile and the platform together and provides analyses that help to provide evidence that can be used as part of a safety case. This paper summarizes key contributions within these areas during the three-year project period. In the conclusion the overall result of the project is assessed.

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Hardware Support for Safety-Critical Java Scope Checks

Cited by 6 publications

References 9 publications

Safety‐critical Java for embedded systems

Safety‐critical Java for embedded systems

An Evaluation of Safety-Critical Java on a Java Processor

Certifiable Java for Embedded Systems

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