• State Not Answered
  • Locked Locked
  • Replies 7 replies
  • Subscribers 350 subscribers
  • Views 3506 views
  • Users 0 members are here
2025 survey

We are running a survey to help us improve the experience for all of our members. If you see the survey appear, please take the time to tell us about your experience if you can.

Options
Related
How was your experience today?
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

is there CPS instruction alternatives to jump from EL1 to EL0 at boot time?

kduplantier

Hello,

I would like to switch from EL1 to EL0 and update my PC in one instruction because I would like to prevent code execution in EL0 mode in my supervisor memory zone.

In order to do that I would like to use ERET instruction or to pop CPSR from stack at boot time instead of using CPS instruction.

I didn't find in the documentation a specific reason to not use ERET at boot time but when I am using it (or when i amp poping cpsr from stack "pop pc^") the behavior is erroneous.

  1. Can someone explain that?
  2. Is there a way  to update PC and CPSR in one instruction at boot time (without erroneous behavior)?

Thanks by advance,

Kevin

Parents
  • 0 in reply to 42Bastian Schick

    I am doing a first eret to jump to el1, then i am loading lrand spsr to do a second eret. After this point the software become unstable. Another company (which is specialized in rtos) has encountered the same problem. We will ask the manufacturer. If you are interested i can forward you the answers. For the moment i trig an hvc as a workaround. 

Reply
  • 0 in reply to 42Bastian Schick

    I am doing a first eret to jump to el1, then i am loading lrand spsr to do a second eret. After this point the software become unstable. Another company (which is specialized in rtos) has encountered the same problem. We will ask the manufacturer. If you are interested i can forward you the answers. For the moment i trig an hvc as a workaround. 

Children