The rate is more like 0.1% than 3% and facebook has published a paper on it too.

Google references a few techniques for working around the issue, and has made libraries for reliable cryptography, but does not link to them.

On Linux thread affinity can be set to select cpu cores: https://man7.org/linux/man-pages/man3/pthread_setaffinity_np.3.html

Google recommends triplicating on different cores crucial tasks.  I suppose you would want to triplicate also the tallying of the results and the verification of being on separate cores.  They link to well-studied techniques in the paper.

The problem is supposed to only affect you if you run a datacenter with thousands of machines, so stop spilling coffee on your mobile phone while running it during an x-ray.

(I recently replaced my copy of raspbian's latest openssl .deb with a handbuilt library because it kept giving me occasional valgrind failures and incorrect digests.)

Obviously this is not a problem that ethereum would ever have.