Messages in this thread | | | Subject | Re: [PATCH v2 0/2] STM32 Extended TrustZone Protection driver | From | Robin Murphy <> | Date | Thu, 1 Mar 2018 14:19:16 +0000 |
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On 01/03/18 14:15, Benjamin Gaignard wrote: > 2018-03-01 15:02 GMT+01:00 Mark Rutland <mark.rutland@arm.com>: >> On Thu, Mar 01, 2018 at 02:58:04PM +0100, Benjamin Gaignard wrote: >>> On early boot stages STM32MP1 platform is able to dedicate some hardware blocks >>> to a secure OS running in TrustZone. >>> We need to avoid using those hardware blocks on non-secure context (i.e. kernel) >>> because read/write accesses could generate illegale access exceptions. >>> >>> Extended TrustZone Protection driver make sure that device is disabled if >>> non-secure world can't acces to it. >>> >>> version 2: >>> - do not use notifier anymore >>> - change status property value in device-tree if needed >>> - use a list of phandle instead of hard coded array >> >> As mentioned on v1, I don't think this should be done in Linux at all. >> >> If you wish to handle this dynamically, please fixup the DT *before* >> entering Linux. >> >> If you want a sane default in the dts file, put status = "disabled" on >> all nodes which the secure world might take ownership of. > > That is the case, nodes are disabled by ealier boot stages before entering > in Linux but, since mistakes and/or errors are always possible, fixup the DT > to avoid illegal access exceptions make sense for me.
So why not also run a test on the memory controller in case the bootloader made a mistake in the memory node too? As I mentioned before, if you can't trust the DT to describe your hardware correctly you've already lost.
Robin.
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