On Sun, Aug 7, 2022 at 10:51 AM Yonghong Song <yhs@xxxxxx> wrote:
>
> Add two program tests with kfunc return types u8/s16.
> With previous patch, xlated codes looks like below:
> ...
> ; return bpf_kfunc_call_test4((struct sock *)sk, (1 << 16) + 0xff00, (1 << 16) + 0xff);
> 5: (bf) r1 = r0
> 6: (b4) w2 = 130816
> 7: (b4) w3 = 65791
> 8: (85) call bpf_kfunc_call_test4#8931696
> 9: (67) r0 <<= 48
> 10: (c7) r0 s>>= 48
> 11: (bc) w6 = w0
> ; }
> 12: (bc) w0 = w6
> 13: (95) exit
> ...
> ; return bpf_kfunc_call_test5((struct sock *)sk, (1 << 8) + 1, (1 << 8) + 2);
> 5: (bf) r1 = r0
> 6: (b4) w2 = 257
> 7: (b4) w3 = 258
> 8: (85) call bpf_kfunc_call_test5#8931712
> 9: (67) r0 <<= 56
> 10: (77) r0 >>= 56
> 11: (bc) w6 = w0
> ; }
> 12: (bc) w0 = w6
> 13: (95) exit
>
> For return type s16, proper sign extension for the return value is done
> for kfunc bpf_kfunc_call_test4(). For return type s8, proper zero
> extension for the return value is done for bpf_kfunc_call_test5().
>
> Without the previous patch, the test kfunc_call will fail with
> ...
> test_main:FAIL:test4-retval unexpected test4-retval: actual 196607 != expected 4294967295
> ...
> test_main:FAIL:test5-retval unexpected test5-retval: actual 515 != expected 3
>
> Signed-off-by: Yonghong Song <yhs@xxxxxx>
> ---
> net/bpf/test_run.c | 12 +++++++
> .../selftests/bpf/prog_tests/kfunc_call.c | 10 ++++++
> .../selftests/bpf/progs/kfunc_call_test.c | 32 +++++++++++++++++++
> 3 files changed, 54 insertions(+)
>
> diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
> index cbc9cd5058cb..3a17ab4107f5 100644
> --- a/net/bpf/test_run.c
> +++ b/net/bpf/test_run.c
> @@ -551,6 +551,16 @@ struct sock * noinline bpf_kfunc_call_test3(struct sock *sk)
> return sk;
> }
>
> +s16 noinline bpf_kfunc_call_test4(struct sock *sk, u32 a, u32 b)
> +{
> + return a + b;
> +}
> +
> +u8 noinline bpf_kfunc_call_test5(struct sock *sk, u32 a, u32 b)
> +{
> + return a + b;
> +}
Is there any upside of adding this to net/bpf/test_run.c instead of
defining it in bpf_testmod?
> +
> struct prog_test_member1 {
> int a;
> };
[...]
