LPC55S69 : Secure boot vs TrustZone

trescurieux — Tue, 13 Oct 2020 09:28:06 GMT

* I have a simple FreeRTOS "blink" app, it works fine when flashed as plain app

* If i sign it, flash it as signed app: It boots fine ( i have serial output), which leads me to believe the signing is ok. But it crashes as soon as freeRTOS scheduler is started

Looking closer, the crash happens when doing the EXC_RETURN call to switch to the 1st thread

The main difference i've spotted so far is that :

* The "plain app" is running with PSP=PSP_S => Secure mode

* The "signed app" is running with PSP=PSP_NS => unsecure mode

I tried doing the provisioning with elf2sb gui with Use Header/TZ Enabled/TZ disabled => not better

(with TZ enabled i dont even reach the serial output)

So the question : Is there an assumption that TrustZone is enabled when using secure boot ?

What's the proper way to have it behave like "plain" app ? It helps as a first step to go the full trustZone way.

Any additional information would be appreciated

Thank you in advance

Tres

Re: LPC55S69 : Secure boot vs TrustZone

trescurieux — Tue, 13 Oct 2020 13:57:43 GMT

Found it :

"enableTrustZone": true in the json configuration file
Works now

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LPC55S69 : Secure boot vs TrustZone

Re: LPC55S69 : Secure boot vs TrustZone