In isolation level 3 partitions code/data in linker script are gathered together and aligned using information from manifest files. Currently there are 2 partitions that are not using manifest files, and instead have hand written load_info.c files. These partitions are: NS agent trust zone and idle partition.
When partition does not have manifest file then its code/data is not gathered together (as there is no manifest to provide needed information). This results in partition code/data being linked directly to SPM. Also code/data may be not correctly aligned (if platform requires special alignment for PSA/APP RoT partitions).
For example if platform define custom TFM_LINKER_PSA_ROT_LINKER_DATA_ALIGNMENT, NS agent TZ and idle partitions stacks will not be aligned properly.
This is a problem because resulting alignment is not sufficient for the platform, which means that functions that apply protections fail.
I see several solutions to this problem:
1. Add alignment to stack of these special partitions. Both the start and the size of the stack should be aligned to satisfy alignment requirements. This is fairly easy fix with small amount of changes. The problem is that code/data of these partitions will still be located in SPM code/data sections which is not ideal solution. I would say this is bare minimum solution, just to make things work. 2. Better solution might be to move these special partitions to now use manifest files. The problem I see is that these partition use special priorities values which are not supported by manifest tool. Also NS Agent TZ uses special PID = 0, which I believe is also not supported by manifest tool. I think this is more time consuming fix but overall this should result in better and easier to understand code.
Would be glad to hear a feedback on this topic.
Regards, Bohdan Hunko
Cypress Semiconductor Ukraine Engineer CSUKR CSS ICW SW FW Mobile: +38099 50 19 714 Bohdan.Hunko@infineon.commailto:Bohdan.Hunko@infineon.com