selftests/bpf: Add kfunc __arena and __arena__nullable argument tests

Add arena-argument kfuncs to bpf_testmod, which also exercises the
argument rebasing on module kfuncs, and tests covering the accepted
argument forms (arena pointer, low 32 bits as a scalar, full user
address as a scalar), the exact rebase semantics via capture kfuncs
returning the raw argument (zero low 32 bits arrive as the arena kernel
base under __arena and as NULL under __arena__nullable), five arena
arguments in one call, a mixed __arena plus __arena__nullable call
exercising both bitmasks on one call site, a kernel-side dereference of
an unpopulated page recovering through the scratch page, and the
rejections (no arena in the program, incompatible register type).

The tests run on x86-64 and skip elsewhere, as programs with
arena-tagged kfunc args fail verification where the JIT lacks support.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://patch.msgid.link/20260808003938.3486067-9-memxor@gmail.com
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>

0 files changed, 0 insertions, 0 deletions