ARM trustzone usage

Question

I would like to ask some questions about ARM trustzone.

1.) Can anyone give me the concrete example: when trustzone is needed and how it helps to solve security problems?

2.) I heared that FIQs could be configured as "secure interrupts". Does it mean that my FIQ handlers will be situated in secure world?

3.) When this FIQ secure / non secure configuration is done? I think the answer is somewhere in the GIC registers. Could i read this registers to be sure about secure / non secure FIQ configuration?

Thanks.

Answer 1

1. It provides an additional level of privilege separation, extended into the interconnect, permitting some other software to run more privileged than (and hence protected from) the main operating system.

2. If you configure Secure interrupts to be delivered as FIQs to Secure world, then the Secure world exception vector table is the one that is used.

3. Whenever you feel like, but generally as part of a Secure OS startup. You can read these registers from Secure world - the Secure registers are not readable from Normal world.

The GIC architecture specification can be downloaded (with registration) from http://infocenter.arm.com/help/topic/com.arm.doc.ihi0048b/index.html