[Ksummit-2013-discuss] [ARM ATTEND] Trustzone-based security solution for ARM Linux

[Dave Martin]

On Fri, Aug 16, 2013 at 10:39:20AM +0800, Barry Song wrote:
> >> >>
> >> >> Isn't that up to the hardware?  Nothing that Linux can do about that.
> >> >
> >> > right. but linux need to assign interrupts to right group in GIC
> >> > hardware. now it doesn't care.
> >>
> >> I strongly hope that whatever is the secure OS is setting up these
> >> routings, and the HW prevents the non-secure OS from modifying them and
> >> hence never attempts to. Otherwise, the non-secure OS is able to affect
> >> the functioning of the secure OS, which seems like a bad thing.
> >
> > Typically, the master controls are hard-wired for Secure-only access in
> > hardware: so assigning GIC interrupts to groups is something the secure
> > OS/firmware has to take care of.
> >
> > Of course, if Linux is acting as secure OS, it might have to understand
> > what controls exist and to do some of that configuration itself.
> 
> that is just what i want. linux need to realize whether it is running
> in security or non-security.
> for example, if one irq is assigned to security, even though users
> want to get it in non-security, linux should make it fail.
> linux need security/non-security realization in GIC.

For just telling Linux where it is and what peripherals are available,
DT feels like the right answer: if Linux is booted Secure, it would have
a different DT from the one it would be given in the Normal World.

The DT provided to Linux in the Normal World might depend on configuration
choices made in the Secure World -- so it might be generated from the
Secure World DT and passed to the Normal World boot stack.  But initially
it's simpler to keep all that stuff static.

Cheers
---Dave