[$] Avoiding retpolines with static calls

Post Syndicated from corbet original https://lwn.net/Articles/815908/rss

January 2018 was a sad time in the kernel community. The Meltdown and
Spectre vulnerabilities had finally been disclosed, and the required
workarounds hurt kernel performance in a number of ways. One of those
workarounds — retpolines
continues to cause pain, with developers going
out of their way to avoid indirect calls, since they must now be implemented
with retpolines. In some cases, though, there may be a way to
avoid retpolines and regain much of the lost performance;
after a long gestation period, the “static calls” mechanism may finally be
nearing the point where it can be merged upstream.