This discussion has been locked.
You can no longer post new replies to this discussion. If you have a question you can start a new discussion

What will I get if I operate p15 to switch to TZ mode when I'm right in TZ mode.

As above~

Parents
  • My question is that when my chip is running in secure mode (trustzone for ARM), and I operate the coprocessor (No.15) trying to switch the ARM mode to Trustzone, i.e.,  secure mode, will that lead to some kind of abort or exception, I'm doing this because I don't know which mode my chip is in.

    So I mean, does ARM core respond to such redundancy operates with some mechanisms to inform me that the chip is already in secure mode.

    Switching worlds directly via the NS bit in CP15 is not recommended, as it is an unmanaged world change. It is recommended that privileged code executes an SMC instruction to cause a transition via the monitor mode / monitor code which manages safe state safe/restore.

    HTH,
    Pete

Reply
  • My question is that when my chip is running in secure mode (trustzone for ARM), and I operate the coprocessor (No.15) trying to switch the ARM mode to Trustzone, i.e.,  secure mode, will that lead to some kind of abort or exception, I'm doing this because I don't know which mode my chip is in.

    So I mean, does ARM core respond to such redundancy operates with some mechanisms to inform me that the chip is already in secure mode.

    Switching worlds directly via the NS bit in CP15 is not recommended, as it is an unmanaged world change. It is recommended that privileged code executes an SMC instruction to cause a transition via the monitor mode / monitor code which manages safe state safe/restore.

    HTH,
    Pete

Children