Function dr_switch_to_dr_state_ex 

pub unsafe extern "C" fn dr_switch_to_dr_state_ex(
    drcontext: *mut c_void,
    flags: dr_state_flags_t,
)

Should only be called after calling dr_switch_to_app_state() (or the _ex version), or in certain cases where a client is running its own code in an application state. Swaps from the application version of system state for the given thread back to the DR and client version.

This function does not affect whether the current machine context (registers) contains application state or not.

A client must call dr_switch_to_dr_state() in order to safely call private library routines if it is running in an application context where dr_using_app_state() returns true. On Windows, this is the case for any application context, as the system state is always swapped. On Linux, however, execution of application code in the code cache only swaps the machine context and not the system state. Thus, on Linux, while in the code cache, dr_using_app_state() will return false, and it is safe to invoke private library routines without calling dr_switch_to_dr_state(). Only if client or client-invoked code will examine a segment selector or descriptor does the state need to be swapped. A state swap is much more expensive on Linux (it requires a system call) than on Windows.

The same flags that were passed to dr_switch_to_app_state_ex() should be passed here.