Patent ID: 7874009

Claim:
A data processing device which has a processor that operates in accordance with a program, and operates by switching an operation mode between a normal mode and a protected mode, wherein, in the normal mode, a process being a unit of execution of the program runs, and in the protected mode, the process is restricted from running, the data processing device comprising: an access prohibit unit operable to, in the normal mode, permit a first process to access process-target data of the first process, and prohibit another process from accessing the process-target data of the first process; a detection unit operable to, in the normal mode, detect a call instruction from the first process to a second process; a switch unit operable to, if the detection unit detects the call instruction, switch the operation mode from the normal mode to the protected mode; a judgment unit operable to, in the protected mode, judge whether or not the second process is authorized to use the process-target data of the first process; and a control unit operable to control the access prohibit unit to permit the second process to access the process-target data of the first process in the normal mode, when the judgment unit, in the protected mode, judges that the second process is authorized to use the process-target data of the first process.