Rooting of Rollipop for Xperia Z2 - Temporary solution
Currently, andriod 5.0.2 firmwares for Xperia Z2/Z3 were released over only Northen EU.
However, unfortunately, the recovery for Rollipop is not available yet at this moment since it might be difficult to port Busybox (maybe due to a new security routine).
We have to wait DualRecovery from XDA to get full root.
I have tried to get root with the similar procedure of 4.4.4, and got the root without Recovery. However, if I upgraded busybox (to enable some APKs that needs Busybox), all things were be messed up.
Anyway, here are my procedure to get root - just keep root without any further manipulation after installation.
1. Get the 5.0.2 firmware from Sony. After that, make FTF by FlashTool. Using the FTF, create your ZIP file to be flashed at Recovery. (Same routine to that of 4.4.4)
http://forum.xda-developers.com/crossdevice-dev/sony/tool-prfcreator-easily-create-pre-t2859904
2. Similar to the case of 4.4.4, we have to downgrade to 4.4.2 to port DualRecovery. After porting DualRecovery, we can enter TWRP. At this time, we have to boot without any manipulation. After booting, by using NDR Util, set the recovery to Phils and go into Phils Recovery.
3. At Phils Recovery, do Erase for "New Rom" + "Dalvik" + "Cache". After Erasing, port "5.0.2 ZIP file" + SuperSU + DualRecovery. Then, reboot.
4. If you enter a new 5.0.2 phone, you can see with Root Explorer that you have "/" directory R/W as default. It means the root is obtained.
5. You cannot write External SD. Then, you search and get the hacked "platform.xml" from XDA. After porting it, you can modify the external SD.. From my experience, if you move Very Large file to External SD, sometimes, you can see the popup that you cannot modify SD. So, please move files with small amount things.
However, I would like to recommend you to wait DualRecovery for getting stable rooting.