Add negative tests that verify the kfunc (rejecting kfunc call
with >8 byte struct as stack argument) and the verifier
(rejecting invalid uses of r11 for stack arguments).
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260513045132.2398371-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
