Bindings to kernel headers?

[akshayknarayan]

Hi, I am writing a simple program that reads the tcp/tcp_probe tracepoint.

A common programming technique when writing BPF programs is including kernel headers to access struct definitions. Indeed, kernelscript init does usefully auto-generate bindings to certain kernel definitions.

Is there an easy way to have kernelscript additionally generate bindings to other values or kernel headers without manually copying them? For tcp/tcp_probe specifically, parsing struct sockaddr_in is relevant.

[congwang]

Good question! Currently kernelscript init only pulls context-related kernel structs from BTF (probably also its dependencies). Without hard-coding, it does not have knowledge to pull other related structs like struct sockaddr_in. Do you have any better ideas here?

[akshayknarayan]

Thanks for the clarification! I agree that pulling in related structs automatically is going to be quite hard, since tracepoint defs erase type info.

A workaround might be to generate further bindings at compile time, with a statement such as the following (extrapolated from the syntax described here: https://github.com/multikernel/kernelscript/blob/main/SPEC.md#14-unified-import-and-include-system)

import "struct sockaddr_in" from "<uapi/linux/in.h>"

[congwang]

Good idea! I think that is feasible.