On Thu, Nov 18, 2021 at 06:39:49PM +0000, Song Liu wrote: > > You're going to have to do that anyway if you're going to write to the > > directmap while executing from the alias. > > Not really. If you look at current version 7/7, the logic is mostly > straightforward. We just make all the writes to the directmap, while > calculate offset from the alias. Then you can do the exact same thing but do the writes to a temp buffer, no different. > >> The BPF program could have up to 1000000 (BPF_COMPLEXITY_LIMIT_INSNS) > >> instructions (BPF instructions). So it could easily go beyond a few > >> pages. Mapping the 2MB page all together should make the logic simpler. > > > > Then copy it in smaller chunks I suppose. > > How fast/slow is the __text_poke routine? I guess we cannot do it thousands > of times per BPF program (in chunks of a few bytes)? You can copy in at least 4k chunks since any 4k will at most use 2 pages, which is what it does. If that's not fast enough we can look at doing bigger chunks.
