selftests/bpf: Add testcase for static kfunc with unused arg

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kfuncs are allowed to be static, or not use one or more of their
arguments. For example, bpf_xdp_metadata_rx_hash() in net/core/xdp.c is
meant to be implemented by drivers, with the default implementation just
returning -EOPNOTSUPP. As described in [0], such kfuncs can have their
arguments elided, which can cause BTF encoding to be skipped. The new
__bpf_kfunc macro should address this, and this patch adds a selftest
which verifies that a static kfunc with at least one unused argument can
still be encoded and invoked by a BPF program.

Signed-off-by: David Vernet <void@manifault.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20230201173016.342758-5-void@manifault.com

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David Vernet 2023-02-01 11:30:16 -06:00 • committed by Daniel Borkmann

parent 400031e05a

commit 6aed15e330

3 changed files with 18 additions and 0 deletions

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6

net/bpf/test_run.c

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1

tools/testing/selftests/bpf/prog_tests/kfunc_call.c

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11

tools/testing/selftests/bpf/progs/kfunc_call_test.c

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