mac OSX Yosemite, safe mode?
After a quick search I found this information:


  If you're in Windows, you can switch to the Mac OS X partition using the Boot Camp icon in the System Tray. Click the gray diamond-shaped icon, and click "Restart in Mac OS" from the pop-up menu. Then, confirm your choice to reboot to Mac OS X.


When you back in OS X you can change the startup disk via sys. pref. > startup disk