Is it possible to get the cores privilege state in user mode ?

[martinschulthei]

Hi,

as mentioned in the question, I want to know if there is a possibility to read out a e.g. core register to get the current privilege state in user mode. (MSR PR-Bit).

Problem is that the MSR is not readable in user mode.

We'd like to add a mechanism to determine whether we need a system call to access specific memory regions (e.g. peripherals which are only accessible in supervisor mode) or not (Performance issues).

The solution should be usable for all e200zX cores.

Thank you in advance and best regards

Martin

[davidtosenovjan]

Hi, as MSR register cannot be read in user mode it can only be done by system call the same way as you would switch to user mode but you would not edit SRR1 content. Thus you will return to user mode, but you may store MSR content (stored in SRR1 during system call).