Hey, I just recently realized that we are still missing multi-kprobe support for ARM64, which depends on CONFIG_FPROBE. And CONFIG_FPROBE seems to require CONFIG_HAVE_RETHOOK, which, it turns out, is not implemented for ARM64. It took me a while to realize what's going on, as I roughly remembered (and confirmed through lore search) that Masami's original rethook patches had arm64-specific bits. Long story short: 0f8f8030038a Revert "arm64: rethook: Add arm64 rethook implementation" 83acdce68949 arm64: rethook: Add arm64 rethook implementation The patch was landed and then reverted. I found some discussion online and it seems like the plan was to land arch-specific bits shortly after bpf-next PR. But it seems like that never happened. Why? I see s390x, RISC-V, loongarch (I'm not even mentioning x86-64) all have CONFIG_HAVE_RETHOOK, even powerpc is getting one (see [0]), it seems. How come ARM64 is the one left out? Can anyone please provide some context? And if that's just an oversight, can we prioritize landing this for ARM64 ASAP? [0] https://lore.kernel.org/bpf/20240830113131.7597-1-adubey@xxxxxxxxxxxxx/ -- Andrii
