Do you trust your immediate supervisor? If not, it's probably a good idea to be looking elsewhere in any case. If you do, ask the direct question: "Am I on the list to be laid off?" Even if he or she "isn't allowed" to tell you, the true answer may be communicated anyway.
Even though it is a dumb question, your boss may ask "Why do you want to know?" (or similar). That gives you a perfect opening to say something such as "well, it would be bad faith on the company's part to fire me just short of my vesting time, wouldn't it?" If they know you are prepared to fight they might just pick someone else. Somewhat dog-eat-dog, but nobody else will care more about you than you yourself so you might as well be firm about it. Nice, but firm.
Sometimes people have good instincts about being on the layoff list, and sometimes fear is much greater than reality justifies. It's entirely possible that your boss could rightly reassure you that you are "safe" (at least for this round). Good luck to you, no matter what transpires.