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trustzone translation table

yaoyao wang
Note: This was originally posted on 15th November 2011 at http://forums.arm.com

After reading the documents in the website, i am quite puzzled about the trustzone feature.
1. Can i disable trustzone extension?
2. Each world has its own virtual processor, virtual mmu and translation table. How to make sure that the normal world can't access the secure world memory? The normal world can't see the physical address of the secure world? Or it can translate the virtual address to the physical address of the secure world, but it can't access that region of memory?
3. Normal world ignores the NS bit in the translation table. So it can access all the physical memory in normal world?
I have read the book: ARM Security Technology: Building a Secure System Using TrustZone Technology, ARM Architecure Reference Manual and ARM Cortex-A programming guide. Did i miss the important part? Can anyone advise me some books regarding the arm cortex-a architecture? I am a beginner at ARM. Thanks.
Parents
  • Note: This was originally posted on 15th November 2011 at http://forums.arm.com

    [color=#222222][size=2]Thanks for your answer, ttfn.[/size][/color]
    [size=2]1. for the second answer, how does the system know it's a secure access. because you mention that all accesses are non-secure in the normal world, though the physical memory is marked as secure in the secure world.[/size]
    [size=2]2. for the third, i mean how to initialize the translation table. If you want initialize the translation table, you should divide the physical space into secure and non-secure. and if you want divide the physical address, you should refer to the NS bit in the translation table. I am confused about this initialization.[/size]
    [size=2]
    [/size]
    [size=2]Thanks.[/size]
Reply
  • Note: This was originally posted on 15th November 2011 at http://forums.arm.com

    [color=#222222][size=2]Thanks for your answer, ttfn.[/size][/color]
    [size=2]1. for the second answer, how does the system know it's a secure access. because you mention that all accesses are non-secure in the normal world, though the physical memory is marked as secure in the secure world.[/size]
    [size=2]2. for the third, i mean how to initialize the translation table. If you want initialize the translation table, you should divide the physical space into secure and non-secure. and if you want divide the physical address, you should refer to the NS bit in the translation table. I am confused about this initialization.[/size]
    [size=2]
    [/size]
    [size=2]Thanks.[/size]
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