ARC Secure Service

Overview

This sample implements a simple secure service based on ARC SecureShield to demonstrate how a secure zephyr application runs together with a normal Zephyr application.

In this sample:

  • Secure application will be in the secure memory space defined in arc_mpu_regions.c. Half of RAM and ROM is allocated to secure world, the other half is allocated to normal world.
  • Memory not allocated to the secure application is allocated to the normal application.
  • By default, all the peripheral space is normal mode accessible, i.e., the peripherals are shared between normal mode and secure mode. If some peripherals are required by secure world, it can be done by adding static mpu entry in arc_mpu_regions.c.
  • The interrupts of two internal timers are configure as normal interrupts, so the normal zephyr’s kernel tick can work correctly.
  • Secure interrupts priority > secure threads priority > normal interrupts priority > normal threads priority.

Requirements

To use this sample, ARC processor should be equipped with ARC SecureShield. In Zephyr, the following board configurations are supported:

  • em_starterkit_em7d * secure application: em_starterkit_em7d_secure * normal application: em_starterkit_em7d_normal
  • nsim_sem * secure application: nsim_sem * normal application: nsim_sem_normal

Building and Running

Building

Secure application

First, you should build the secure application.

Using west:

west build -b em_starterkit_em7d_secure nsim_sem samples/boards/arc_secure_services

Using CMake and ninja:

cmake -B build -GNinja -DBOARD=em_starterkit_em7d_secure nsim_sem samples/boards/arc_secure_services
ninja -C build

Normal application

Currently, in normal application, MPU is not accessible, so no user space and mpu-based stack checking.

Here,take :ref:’dining-philosophers-sample’ as an example for normal application.

Using west:

west build -b em_starterkit_em7d_normal nsim_sem_normal samples/philosophers

Using CMake and ninja:

cmake -B build -GNinja -DBOARD=em_starterkit_em7d_normal nsim_sem_normal samples/philosophers
ninja -C build

Running

  • Run using the bootloader

The bootloader should load the secure and normal application into the correct place, then jump to the entry of the secure application. The entry of normal application is hardcoded in secure application. Secure application will boot normal application.

  • Run using the debugger (recommended)

Use the gdb debugger to load and run the two applications.

For em starter kit, run the following commands

# load secure application first
$ cd samples/boards/arc_secure_services/build
$ west debug
# load normal application
$ monitor load_image ../../../philosophers/build/zepher/zephyr.elf
$ c

For nsim sem, you need two consoles: one for application output, and one for debugger.

In the console for output:

# open debug server
$ cd samples/boards/arc_secure_services/build
$ west debugserver

In the console for debugger:

# open debug server
$ cd samples/boards/arc_secure_services/build
$ arc-elf32-gdb zephyr/zephyr.elf
$ target remote :3333
# load normal application
$ load ../../../philosophers/build/zepher/zephyr.elf
# load secure application
$ load
$ c