Re: [PATCH bpf v2 2/2] selftests/bpf: Test r0 bounds after BPF to BPF call with abnormal return

[Eduard Zingerman <eddyz87@xxxxxxxxx>]

On Mon, 2024-12-16 at 18:39 +0100, Arthur Fabre wrote:

[...]

> It might not be possible to do them both entirely: clang also doesn't
> know that bpf_tail_call() can return, so it assumes the callee() will
> return a constant r0. It sometimes optimizes branches / loads out
> because of this.

Hm, haven't thought about this.
You would need assembly to hide the r0 indeed.