[Q] need help rooting my st15i topic

Hi i need help rooting my st15i. Here some information about my phone

Android version: 2.3.4
Baseband version: 8x55A- AAABQOAZM-203028D-86
Kernel version: 2.6.32.9-perf SEMCUser@SEMCHost#1
Build number: 4.0.2.A.0.84

Do i need to upgrade anything?