Rivendell was under siege by Sauron's army for a large part of the Second Age, so I should imagine that Sauron knew pretty much where it was.
Lorien was, as FinII has said, assailed by Sauron's forces during the War of the Ring so ditto.
With regard to Rivendell at least, this knowledge pre-dated Saruman's arrival in Middle-earth.
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Do you mind? I'm busy doing the fishstick. It's a very delicate state of mind!
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