Core Special Function Register Change from User Mode

[User22023]

Hi all,

how can i change the CSFR´s when i´m in user mode? I´ve seen that with the syscall trap it is possible to get in the supervisor mode and now i want to change in the TrapHook for example the PSW.PRS bits but when i exit the syscall trap the upper and lower context is restored and so the changes are not accepted.
How can i make changes to the PSW and hold these changes after the rslcx and RFE at the end from the traphandler. I´ve tried to manipulate the CSA´s this worked, but i think this is not the way it has to be done.

BR Hennessy

[Darren_Galpin]

In most cases you cannot, and this is a deliberate safety mechanism to prevent unintended access. You must switch to supervisor mode to change register settings by software.

[indra]

Hi @User22023  @Darren_Galpin , I have a question how did you switch to user mode

[Vamshi_V]

Hi, @User22023 did you find any solution about how to change CSFR when you're in user mode or can you please explain how did you manipulate the CSA to change the contents of PSW ??