On Wed, Jan 24, 2024 at 12:25 AM Jose E. Marchesi
<jose.marchesi@xxxxxxxxxx> wrote:
>
>
> > On 1/23/24 10:59 AM, Jose E. Marchesi wrote:
> >> The definition of bpf_tail_call_static in tools/lib/bpf/bpf_helpers.h
> >> is guarded by a preprocessor check to assure that clang is recent
> >> enough to support it. This patch updates the guard so the function is
> >> compiled when using GCC as well.
> >>
> >> Tested in bpf-next master.
> >> No regressions.
> >>
> >> Signed-off-by: Jose E. Marchesi <jose.marchesi@xxxxxxxxxx>
> >> Cc: Yonghong Song <yhs@xxxxxxxx>
> >> Cc: Eduard Zingerman <eddyz87@xxxxxxxxx>
> >> Cc: david.faust@xxxxxxxxxx
> >> Cc: cupertino.miranda@xxxxxxxxxx
> >> ---
> >> tools/lib/bpf/bpf_helpers.h | 2 +-
> >> 1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
> >> index 2324cc42b017..3306f50c5081 100644
> >> --- a/tools/lib/bpf/bpf_helpers.h
> >> +++ b/tools/lib/bpf/bpf_helpers.h
> >> @@ -136,7 +136,7 @@
> >> /*
> >> * Helper function to perform a tail call with a constant/immediate map slot.
> >> */
> >> -#if __clang_major__ >= 8 && defined(__bpf__)
> >> +#if (!defined(__clang__) || __clang_major__ >= 8) && defined(__bpf__)
> >
> > Do you want to guard with a gcc version as well here or you assume any gcc which supports bpf
> > should be okay here?
>
> The second, because GCC versions that do not support
> bpf_tail_call_static are not capable of building the selftests for many
> other reasons, so there is little point to support them.
bpf_helpers.h is part of libbpf-provided API, and so it's going to be
used way beyond just BPF selftests. So I think it's prudent to guard
with version check just like we do it for clang. I assume you do know
GCC version that is meant to support this?
>
> >
> >> static __always_inline void
> >> bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
> >> {
>
