.. _mpu_test:
Memory Protection Unit (MPU) Sample
###################################
Overview
********
This application provides a set options to check the correct MPU configuration
against the following security issues:
* Read at an address that is reserved in the memory map.
* Write into the boot Flash/ROM.
* Run code located in SRAM.
If the MPU configuration is correct each option selected ends up in an MPU
fault.
Building and Running
********************
This project can be built and executed as follows:
.. zephyr-app-commands::
:zephyr-app: samples/mpu/mpu_test
:board: v2m_beetle
:goals: build flash
:compact:
To build the single thread version, use the supplied configuration file for
single thread: :file:`prj_single.conf`:
.. zephyr-app-commands::
:zephyr-app: samples/mpu/mpu_test
:board: v2m_beetle
:conf: prj_single.conf
:goals: run
:compact:
To build a version that allows writes to the flash device, edit
``prj.conf``, and follow the directions in the comments to enable the
proper configs.
Sample Output
=============
.. code-block:: console
uart:~$ mpu read
<err> os: ***** BUS FAULT *****
<err> os: Precise data bus error
<err> os: BFAR Address: 0x24000000
<err> os: r0/a1: 0x00009a5c r1/a2: 0x00000008 r2/a3: 0x20001aa8
<err> os: r3/a4: 0x24000000 r12/ip: 0x00000000 r14/lr: 0x000029b7
<err> os: xpsr: 0x21000000
<err> os: Faulting instruction address (r15/pc): 0x000003c8
<err> os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0
<err> os: Current thread: 0x20000708 (shell_uart)
<err> os: Halting system
.. code-block:: console
uart:~$ mpu write
write address: 0x4000
<err> os: ***** MPU FAULT *****
<err> os: Data Access Violation
<err> os: MMFAR Address: 0x4000
<err> os: r0/a1: 0x00000000 r1/a2: 0x0000000e r2/a3: 0x0badc0de
<err> os: r3/a4: 0x00004000 r12/ip: 0x00000004 r14/lr: 0x000003ab
<err> os: xpsr: 0x61000000
<err> os: Faulting instruction address (r15/pc): 0x000003b2
<err> os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0
<err> os: Current thread: 0x20000708 (shell_uart)
<err> os: Halting system
.. code-block:: console
uart:~$ mpu run
<err> os: ***** MPU FAULT *****
<err> os: Instruction Access Violation
<err> os: r0/a1: 0x00009a5c r1/a2: 0x00000001 r2/a3: 0x20001aa8
<err> os: r3/a4: 0x20000000 r12/ip: 0x00000000 r14/lr: 0x00006673
<err> os: xpsr: 0x60000000
<err> os: Faulting instruction address (r15/pc): 0x20000000
<err> os: >>> ZEPHYR FATAL ERROR 0: CPU exception on CPU 0
<err> os: Current thread: 0x20000708 (shell_uart)
<err> os: Halting system
17d64e0bf9