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Control MMU for TrustZone

thiet pv
Note: This was originally posted on 20th July 2011 at http://forums.arm.com

Dear all,
I am a new bie about TrustZone. I arm learning the effect of TrustZone to MMU. I have some problems about the mechanism to manage secure/non-secure region by MMU.
Please help me to understand about them.
My dubious point described as below:
   When translation virtual address to physical address, system will use TLB table. I know that, when have a miss occur on TLB, it will find physical page from page table.
From table index of virtual address and table base address, will have first-level descriptor, the first-level descriptor will be input for page table to get physical page table from page table
then fill it to TLB table.
If page table miss, it will find physical page form external memory (RAM) and fill it to page table with it's attribute.
So when cpu stay in secure world, and access to secure physical memory
     How to know the address that cpu access include secure physical memory region or no-secure physical memory region?
     How to partition the physical memory into secure and non-secure regions?
and if know secure attribute of secure region then
     How to fill secure attribute to page table?
Please help me.
Thank you very much,
Parents
  • Note: This was originally posted on 22nd July 2011 at http://forums.arm.com

    Thanks for reply,
    I still some dubious point.
    I know that each line on TLB has 2 attribute NS and NSTID. They will specify the descriptor and physical page on each line of TLB is secure or non-secure.
    But when has a miss TLB, it must find corresponding physical page at page table then fill it to TLB, so
        How to specify this physical page is secure or non-secure?
    and
        How will TLB update NS and NSTID for this entry?
    Can you indicate them for me?
Reply
  • Note: This was originally posted on 22nd July 2011 at http://forums.arm.com

    Thanks for reply,
    I still some dubious point.
    I know that each line on TLB has 2 attribute NS and NSTID. They will specify the descriptor and physical page on each line of TLB is secure or non-secure.
    But when has a miss TLB, it must find corresponding physical page at page table then fill it to TLB, so
        How to specify this physical page is secure or non-secure?
    and
        How will TLB update NS and NSTID for this entry?
    Can you indicate them for me?
Children
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