My understanding of the term 'patent troll' is that it only applies to companies that own but do not actually use their patents to bring things to market themselves. Thus, the companies you mention don't qualify. Not to say that what those companies do is all peaches and cream but it's not patent trolling.
Apple, Samsung, Google and Oracle are all practicing entities. They're not trolls.
What they're doing law-suit wise is a power-play, a tit-for-tat that's started to escalate into dangerous nuclear territory.
Although there is some debate about the exact meaning of "patent troll", I would think that using the threat of litigation to prevent innovation falls under this.