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Memory protection mechanisms have become important in an embedded system. Previously, embedded systems, especially small-size systems, did not need memory protection mechanisms. However, recent embedded systems require memory protection mechanisms. That is because large, complex programs in a large embedded system, such as car navigation systems an...
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... integrate the generic memory protection mechanism with the access control framework in TECS [3]. In TECS, a security component provides secure functionalities such access control and is inserted between components in the unprotected area and the protected area. An example of us- age of the security component is shown in Fig. 6. In this case, the security component restricts access from A to B. The security component is one of the cells (components) that control the access between ...
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Citations
Memory protection plays an important role in ensuring the safety of real-time embedded operating system. In order to solve the hardware support restriction in AUTOSAR OS memory protection approach, this paper proposes a software-based solution. This method creates a memory access vector table for each task, and corresponding algorithm is developed to reduce overheads. Moreover, this method uses random algorithm to increase the accuracy of stack measurement. The solution is implemented in SmartOSEK OS, experimental results in HCS12, HCS12X and MPC5634 hardware platforms show that this method enhances the efficiency of AUTOSAR OS memory protection software solution, and is not hardware related so it is more versatile.
A strategy and implementation for the isolation and protection mechanism of automotive embedded operating system is described. Upon limited hardware resources, the software mechanism satisfies the three-level isolation and protection requirements covering operating system, applications, tasks and interrupt service routines. A protection error handling mechanism is provided with the ability of restricting memory accessing errors to limited regions, reducing the probability of the whole system's failure. The number of memory pages is reduced apparently along with the improvement of operating system performance and utility of memory space. An automotive embedded operating system with isolation and protection mechanism can integrate software components of different sources and safety integration levels into a same ECU system.
Memory protection mechanisms have become important in embedded systems because programs are becoming larger and more complex, and the failure of one program can corrupt other programs. In order to isolate failures and to prevent the failure of one program from propagating throughout the system, memory protection is required.
Recently, memory protection is also required in safety-critical embedded systems.
In embedded systems, the memory protection mechanisms are used the memory management unit (MMU) function in a CPU. However, the overhead cost of system calls to the OS is very large because the system calls are implemented by a software trap, which decreases the system performance. The goal of the present study is to provide a lightweight memory protection mechanism in the privilege memory space in order to protect a real-time OS from unintended behaviors of application programs in the privilege memory space.
An application program in the privilege level in an embedded system, which is accessible to registers in peripheral devices and can execute privilege instructions for the embedded system, is crucial.
We design and implement the light memory protection mechanism in the privilege memory space in real-time OS using MMU in ARM processor.
We show that our memory protection mechanism is effective in a real application because of very small increase of execution time.
For Embedded Real Time OS, making use of the MMU features, especially memory protection, is important to meet the needs of those embedded real time applications which requires such support. This paper is meant to implement a memory protection system focused on embedded real time OS. The system is based on memory domain table management. The memory domain table is the data structure to manage memory blocks with access attribute based on MMU support. A suit of architecture independent APIs were provided to set the address and attributes of memory.
Recently, applications in embedded systems have increasingly become complex. This requires having tools to prevent or detect memory corruption errors during the software development process. Unfortunately, because of hardware cost and performance penalty, most of embedded processors lack to be equipped a MMU (Memory Management Units) which allows protecting memory accesses in general purpose computer systems. In this paper, an approach to detect memory corruption at run-time by combining hardware/software is presented. A FPGA-based off-chip detector is proposed. It is hooked on memory bus to monitor memory access for multitasking Real-time Operating System (RTOS) applications. Some testbeds are used for evaluating this model and they give good results. Besides, a comparison of real-time schedulability is also carried out. Our solution causes the real-time schedulability of the system dropped-off 9,63%.
Recently, application in embedded systems has increasingly become complex. This requires having tools to prevent or detect memory corruption errors during the software development process. Unfortunately, most of embedded processors lack to be equipped a MMU (Memory Management Units), one of hardware components supporting memory protection mechanism in general purpose computer system, because MMU-based memory protection methods cause embedded system incurred hardware cost and performance penalty. In this paper, an off-chip model is proposed to detect violated memory accesses at run-time without incurring hardware cost. It can efficiently detect errors for RTOS-based applications in cases of stack overflow, reading/writing to code/data segments of the other tasks or violated memory access to OS kernel. The hardware component based on FPGA is also built by hooking on memory system bus to monitor memory accesses. Once error detection phase is completed, the hardware prototype can be detached from the system. Some testbeds are used for this model and give good results.
To deploy a memory protection mechanism, it requires CPU support hardware components like Memory Management Unit (MMU) or Memory Protection Unit (MPU). However, in embedded system, most of microcontrollers lack to be equipped these features because they cause the system incurred hardware cost and performance penalty. In this paper, a method to detect memory corruption at run-time without incurring hardware cost is proposed. Embedded system processor does not require having MMU or MPU. Off-chip detection based on FPGA by hooking on memory bus to monitor memory access for multitasking Realtime Operating System (RTOS) application is explored. Our solution, called MemMON, by combining hardware/software can detect memory access error such as task's stack overflow, task's reading/writing to code/data segments of the other tasks or memory access violation to OS kernel efficiently. In experimental evaluation, a comparison of realtime schedulability is carried out for both using and not using MemMON. Using our MemMON causes realtime schedulability of the system dropped-off about 3 times.
