TrustZone example on i.MX6

Markku Ahvenjärvi markku.ahvenjarvi at nomovok.com
Tue Dec 23 14:39:09 CET 2014


Hello hackers,

I'm trying to run Fiasco.OC in secure world and Linux in non-secure 
world on i.MX6Q. For this I'm using the TrustZone example 
(pkg/examples/sys/vm-tz). To secure world I have given 128MB RAM 
starting from 0x10000000 and I modified the example to give NS world 
256MB starting from 0x20000000. I've replaced atags with dtb of my board 
and it is copied to NS side like kernel and initrd.

At first I encountered runtime exception, which I fixed by implementing 
following to arm_em_tz builds
Thread::arch_ext_vcpu_enabled() { return true; }

Now I'm having problems at early stages of NS boot, where Linux kernel 
is checking for the dtb magic. The code loads the dtb magic from the 
address I'm giving in r2 register (0x21000000), but the magic value 
usually have one byte or all of them incorrect.

I've used JDB to dump the area of dtb after hitting that error and it 
shows the dtb magic properly. So for some reason the NS-world gets 
mangled value. Any idea what might be causing this?

Thanks,
Markku



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