On Mon, Jan 05, 2026 at 03:20:13PM -0800, Andrii Nakryiko wrote:

On Mon, Jan 5, 2026 at 2:33 PM Alexei Starovoitov
[off-list ref] wrote:

quoted

On Sun, Jan 4, 2026 at 4:28 AM Menglong Dong [off-list ref] wrote:

quoted

In current solution, we can't reuse the existing bpf_session_cookie() and
bpf_session_is_return(), as their prototype is different from
bpf_fsession_is_return() and bpf_fsession_cookie(). In
bpf_fsession_cookie(), we need the function argument "void *ctx" to get
the cookie. However, the prototype of bpf_session_cookie() is "void".

I think it's ok to change proto to bpf_session_cookie(void *ctx)
for kprobe-session. It's not widely used yet, so proto change is ok
if it helps to simplify this tramp-session code.
I see that you adjust get_kfunc_ptr_arg_type(), so the verifier
will enforce PTR_TO_CTX for kprobe and trampoline.
Potentially can relax and enforce r1==ctx only for trampoline,
but I would do it for both for consistency.

Yeah, I'd support that. It's early enough that this shouldn't be
breaking a lot of users (if any).

Jiri, do you guys use bpf_session_is_return() or bpf_session_cookie()
anywhere already?

np, we can still adjust, it's in PR that's not merged yet

jirka