DOOM in the kernel, or fibers in eBPF

In the maker’s words

Some time ago my coworker who was working on first version of Perforator ( https://github.com/yandex/perforator ) kept talking about eBPF, so I got curious about its ISA and restrictions. That was around the time I read about DOOM on pregnancy test, so I thought: "what if someone run DOOM inside of Linux kernel in eBPF? Surely, with some restrictions, this should still be possible?" I started to play around with it somewhere in 2024 - first stripping DOOM to bare minimum that is needed for showcase, simplifying code and trying to pass first restrictions that I encountered - function limit, recursion, memory access and checks. I tried to do this by hand, but it was, well, tedious labor. So I changed direction and instead started to do some of the things with LLVM-passes - rewriting memory access, simplifying and rewriting loops etc. But there were just so many corners. And given absence o…

Where people found it

• Hacker NewsShow HN: DOOM in the kernel, or fibers in eBPF53 points14 comments24 days ago