Phone holders in cars

On my next trip, I'm renting a car. While that car will probably have a good satnav built in, I like to have a backup, which will be my phone.

I wondered if it's legal to use a phone mount that utilises a suction cup on the windscreen. I figured that will be the most universally fitting mounting option, as I can't be sure if any other type of mount will fit, or even stay in place.

I know it's not legal everywhere in the world, so I thought better safe than sorry and ask. It's surprisingly hard to find this kind of information.

Now I do see that Yodobashi sells this type of product, but that doesn't neccesarily say anything about where I'm allowed to mount it, or even if those are even meant for windscreen mounting in the first place.