There are some issues with the bpf/nat6to4.c building.

1. It use TEST_CUSTOM_PROGS, which will add the nat6to4.o to
   kselftest-list file and run by common run_tests.
2. When building the test via `make -C tools/testing/selftests/
   TARGETS="net"`, the nat6to4.o will be build in selftests/net/bpf/
   folder. But in test udpgro_frglist.sh it refers to ../bpf/nat6to4.o.
   The correct path should be ./bpf/nat6to4.o.
3. If building the test via `make -C tools/testing/selftests/ TARGETS="net"
   install`. The nat6to4.o will be installed to kselftest_install/net/
   folder. Then the udpgro_frglist.sh should refer to ./nat6to4.o.

To fix the confusing test path, let's just move the nat6to4.c to net folder
and build it as TEST_GEN_FILES.

Fixes: edae34a3ed92 ("selftests net: add UDP GRO fraglist + bpf self-tests")
Tested-by: Björn Töpel <bjorn@kernel.org>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20230118020927.3971864-1-liuhangbin@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

The BPF Makefile in net/bpf did incorrect path substitution for O=dir
builds, e.g.

  make O=/tmp/kselftest headers
  make O=/tmp/kselftest -C tools/testing/selftests

would fail in selftest builds [1] net/ with

  clang-16: error: no such file or directory: 'kselftest/net/bpf/nat6to4.c'
  clang-16: error: no input files

Add a pattern prerequisite and an order-only-prerequisite (for
creating the directory), to resolve the issue.

[1] https://lore.kernel.org/all/202212060009.34CkQmCN-lkp@intel.com/

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 837a3d66d698 ("selftests: net: Add cross-compilation support for BPF programs")
Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Link: https://lore.kernel.org/r/20221206102838.272584-1-bjorn@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

The selftests/net does not have proper cross-compilation support, and
does not properly state libbpf as a dependency. Mimic/copy the BPF
build from selftests/bpf, which has the nice side-effect that libbpf
is built as well.

Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Anders Roxell <anders.roxell@linaro.org>
Link: https://lore.kernel.org/r/20221119171841.2014936-1-bjorn@kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

The incorrect path is causing the following error when trying to run net
kselftests:

In file included from bpf/nat6to4.c:43:
../../../lib/bpf/bpf_helpers.h:11:10: fatal error: 'bpf_helper_defs.h' file not found
         ^~~~~~~~~~~~~~~~~~~
1 error generated.

Fixes: cf67838c4422 ("selftests net: fix bpf build error")
Signed-off-by: Coleman Dietsch <dietschc@csp.edu>
Link: https://lore.kernel.org/r/20220628174744.7908-1-dietschc@csp.edu
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bpf_helpers.h has been moved to tools/lib/bpf since 5.10, so add more
including path.

Fixes: edae34a3ed92 ("selftests net: add UDP GRO fraglist + bpf self-tests")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Lina Wang <lina.wang@mediatek.com>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20220606064517.8175-1-lina.wang@mediatek.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

When NET_F_F_GRO_FRAGLIST is enabled and bpf_skb_change_proto is used,
check if udp packets and tcp packets are successfully delivered to user
space. If wrong udp packets are delivered, udpgso_bench_rx will exit
with "Initial byte out of range"

Signed-off-by: Maciej enczykowski <maze@google.com>
Signed-off-by: Lina Wang <lina.wang@mediatek.com>
Signed-off-by: David S. Miller <davem@davemloft.net>