AUTOSAR

AUTOSAR

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  • Arun Pulinatu
    Arun Pulinatu
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    Memory Protection in AUTOSAR
    Hi All,

    Can someone please tell me how memory protection is implemented in AUTOSAR 3.0.
    Suppose I am using target processor as PowerPC (which has MPU), how can OS, configured
    under SC3/SC4 ensure memory protection?

    My requirement is specifically for scenario where multiple applications reside on the same ECU.
    Hence I need a mechanism to ensure the read/write protection of:
    1. Stack area of each Task
    2. NvM allocated to each application

    Although NvM has a NvM_SetBlockProtection API, this API cannot differentiate between different applications
    and Fee blocks/Nv Blocks assigned to different applications.

    So, how is a rougue application prevented from accessing data that it should not access.

    Also, in AUTOSAR do we have any concept of RAM protection (other than through private stack of each task)?
    For, if we have RAM variables that are global, they will be accessible to all software.

    Warm Regards,
    Arun
    • 11 Aug 2010, 11:27 am
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    Jean-Luc Béchennec
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    Re: Memory Protection in AUTOSAR
    Hi Arun

    Arun Pulinatu a écrit:
    Hi All,
     
    Can someone please tell me how memory protection is implemented in AUTOSAR 3.0.
    Suppose I am using target processor as PowerPC (which has MPU), how can OS, configured
    under SC3/SC4 ensure memory protection?
    I can explain how I implemented it in Trampoline 2

    Each non-trusted task/ISR2 has r/w access to 3 data memory regions :
    its stack (1 MPU descriptor)
    its data (1 MPU descriptor)
    the data of the OS Application the task/ISR2 belongs to (1 MPU descriptor)

    In the memory mapping I interleave the stack of tasks/ISR then the private data then the data of the OS Applications
    That way, a stack cannot overflow or underflow in the data.

    Consts and programs are contiguous and protected against writing (in the case they are located in RAM)

    The rest of memory space cannot be accessed (I/O and unmapped memory regions)

    No special configuration is required, the system generation tool (goil in our case) generates a MemMap.h with segments for each task/ISR. It generates also a link script to map these regions. Memory regions descriptors used to program the MPU when the kernel (OS) switches context are also generated. A different generation tool should do the same

    One of the Memory Protection AUTOSAR requirements is not yet supported: the access to I/O.

     
    My requirement is specifically for scenario where multiple applications reside on the same ECU.
    Hence I need a mechanism to ensure the read/write protection of:
    1. Stack area of each Task
    2. NvM allocated to each application
     
    Although NvM has a NvM_SetBlockProtection API, this API cannot differentiate between different applications
    and Fee blocks/Nv Blocks assigned to different applications.
     
    For NvM, I don't know

    So, how is a rougue application prevented from accessing data that it should not access.
     
    Also, in AUTOSAR do we have any concept of RAM protection (other than through private stack of each task)?
    Yes, see above

    For, if we have RAM variables that are global, they will be accessible to all software.
    No, these variables should be in an OS Application data region

    But consts are accessible

    Best regards
    This post was modified on 20 Oct 2010 at 12:24 pm.
    • 20 Oct 2010, 12:04 pm
  • Yannick Moreaux
    Yannick Moreaux
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    Re^2: Memory Protection in AUTOSAR
    Hello,

    You have some problems, in AutoSAR Release R3.0 specifications, Memory Protection in only defined for AUTOSAR OS, but not for RTE... . If you want to develop an AUTOSAR application with AutoSAR Software Components( SW-Cs) and Memory Protection you need AutoSAR Release R4.0. I am not sure that there are already AutoSAR R4.0 tools and COTS on the market.

    You can use Memory Protection with your AUTOSAR OS R3.0 if you don't need Memory Protection between SW-Cs.

    The configuration of Memory Protection for AUTOSAR OS R3.0 is not standardized. It is specific to the OS vendor. You have to look to your OS manual.

    You can protect the stack of your tasks without Memory Protection. It is in OSEK specifications, and so in AUTOSAR OS. But the check of the integrity of the stack is only realized at tasks switch. It is generally implemented just with a tag value in stack bottom.

    The NvM_SetBlockProtection API is something different from Memory Protection of RAM memory. If just an API to toggle a flag located in the EEPROM and associated with the NvM Block you want to modify.


    Best Regards and salutations to IRCCyN
    This post was modified on 23 Oct 2010 at 11:47 am.
    • 23 Oct 2010, 11:35 am
  • Arun Pulinatu
    Arun Pulinatu
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    Re^3: Memory Protection in AUTOSAR
    Thank you all for your feedback.

    Regards,
    Arun
    • 05 Jan 2011, 07:23 am