Hi Mathieu,
I've finished the verification of STM master stuff on Juno. We indeed don't need to care about which master the trace data should go from software side.
The attachments are the result, one is the trace output from Ftrace another is the decoding result with Mike's CS-STM decoding library.
FYI:
The CPUs and associated STM Mater id on Juno are: CPU Master ID 0 A53 core0 0x44 1 A57 core0 0x40 2 A57 core1 0x41 3 A53 core1 0x45 4 A53 core2 0x46 5 A53 core3 0x47
Regard, Chunyan