what Ossiblue said. See the glob of cement on top of the fallen tile? That was under the flashing. Cut tile with a small grinder and a diamond blade. Shove it back up there and install with a dab of glue (put a little more then that, will ya Sid). Not sure if drilling new holes that close to the edge without cracking the tile is possible. I have done it with 50% success. That would be the best way to ensure that the mechanical fastener will make it stay put for good even if the mastic fails. Most roofer just mastic along with cement and call it the day. They stay put pretty well until the big earthquake.
You will be fine.
Whenyou get up there, seal up that crack or opening with something to keep bees or other insect from entering the home.