Determines whether read access to the virtual address specified by
  __address bits {60:0} and the region register indexed by __address
  bits {63:61} is permitted at the privilege level given by __mode
  bits {1:0}.  It returns 1 if the access is permitted, and 0
  otherwise.

  This function can probe only with equal or lower privilege levels.
  If the specified privilege level is higher (lower number), then the
  probe is performed with the current privilege level.

  This function is the same as the Intel __probe_r function.

  Syntax:

       int __prober (__int64 __address, unsigned int __mode);