kernel/tools/testing/selftests/bpf/testing_helpers.h, branch linux-rolling-stable

selftests/bpf: Add stress test for rqspinlock in NMI

2025-09-28T10:18:40Z

Introduce a kernel module that will exercise lock acquisition in the NMI path, and bias toward creating contention such that NMI waiters end up being non-head waiters. Prior to the rqspinlock fix made in the commit 0d80e7f951be ("rqspinlock: Choose trylock fallback for NMI waiters"), it was possible for the queueing path of non-head waiters to get stuck in NMI, which this stress test reproduces fairly easily with just 3 CPUs. Both AA and ABBA flavors are supported, and it will serve as a test case for future fixes that address this corner case. More information about the problem in question is available in the commit cited above. When the fix is reverted, this stress test will lock up the system. To enable this test automatically through the test_progs infrastructure, add a load_module_params API to exercise both AA and ABBA cases when running the test. Note that the test runs for at most 5 seconds, and becomes a noop after that, in order to allow the system to make forward progress. In addition, CPU 0 is always kept untouched by the created threads and NMIs. The test will automatically scale to the number of available online CPUs. Note that at least 3 CPUs are necessary to run this test, hence skip the selftest in case the environment has less than 3 CPUs available. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20250927205304.199760-1-memxor@gmail.com Signed-off-by: Alexei Starovoitov

selftests/bpf: Provide a generic [un]load_module helper

2024-10-10T17:44:03Z

Generalize the previous [un]load_bpf_testmod() helpers (in testing_helpers.c) to the more generic [un]load_module(), which can load an arbitrary kernel module by name. This allows future selftests to more easily load custom kernel modules other than bpf_testmod.ko. Refactor [un]load_bpf_testmod() to wrap this new helper. Signed-off-by: Simon Sundberg Acked-by: Jiri Olsa Acked-by: Kumar Kartikeya Dwivedi Signed-off-by: Toke Høiland-Jørgensen Link: https://lore.kernel.org/r/20241010-fix-kfunc-btf-caching-for-modules-v2-2-745af6c1af98@redhat.com Signed-off-by: Alexei Starovoitov

selftests/bpf: Test case for lacking CFI stub functions.

2024-02-22T20:26:41Z

Ensure struct_ops rejects the registration of struct_ops types without proper CFI stub functions. bpf_test_no_cfi.ko is a module that attempts to register a struct_ops type called "bpf_test_no_cfi_ops" with cfi_stubs of NULL and non-NULL value. The NULL one should fail, and the non-NULL one should succeed. The module can only be loaded successfully if these registrations yield the expected results. Signed-off-by: Kui-Feng Lee Link: https://lore.kernel.org/r/20240222021105.1180475-3-thinker.li@gmail.com Signed-off-by: Martin KaFai Lau

selftests/bpf: Move is_jit_enabled() into testing_helpers

2024-01-24T04:26:17Z

Currently, is_jit_enabled() is only used in test_progs, move it into testing_helpers so that it can be used in test_verifier. While at it, remove the second argument "0" of open() as Hou Tao suggested. Signed-off-by: Tiezhu Yang Signed-off-by: Andrii Nakryiko Acked-by: Hou Tao Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20240123090351.2207-2-yangtiezhu@loongson.cn

selftests/bpf: detect testing prog flags support

2024-01-23T22:40:22Z

Various tests specify extra testing prog_flags when loading BPF programs, like BPF_F_TEST_RND_HI32, and more recently also BPF_F_TEST_REG_INVARIANTS. While BPF_F_TEST_RND_HI32 is old enough to not cause much problem on older kernels, BPF_F_TEST_REG_INVARIANTS is very fresh and unconditionally specifying it causes selftests to fail on even slightly outdated kernels. This breaks libbpf CI test against 4.9 and 5.15 kernels, it can break some local development (done outside of VM), etc. To prevent this, and guard against similar problems in the future, do runtime detection of supported "testing flags", and only provide those that host kernel recognizes. Acked-by: Song Liu Acked-by: Jiri Olsa Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20240109231738.575844-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov

selftests/bpf: Factor out get_xlated_program() helper

2024-01-23T22:40:21Z

Both test_verifier and test_progs use get_xlated_program(), so moving the helper into testing_helpers.h to reuse it. Acked-by: Eduard Zingerman Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20240105104819.3916743-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov

selftests/bpf: Check VLAN tag and proto in xdp_metadata

2023-12-14T00:16:41Z

Verify, whether VLAN tag and proto are set correctly. To simulate "stripped" VLAN tag on veth, send test packet from VLAN interface. Also, add TO_STR() macro for convenience. Acked-by: Stanislav Fomichev Signed-off-by: Larysa Zaremba Link: https://lore.kernel.org/r/20231205210847.28460-19-larysa.zaremba@intel.com Signed-off-by: Alexei Starovoitov

selftests/bpf: Move get_time_ns to testing_helpers.h

2023-08-21T22:51:26Z

We'd like to have single copy of get_time_ns used b bench and test_progs, but we can't just include bench.h, because of conflicting 'struct env' objects. Moving get_time_ns to testing_helpers.h which is being included by both bench and test_progs objects. Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20230809083440.3209381-19-jolsa@kernel.org Signed-off-by: Alexei Starovoitov

selftests/bpf: Use un/load_bpf_testmod functions in tests

2023-05-17T05:09:23Z

Now that we have un/load_bpf_testmod helpers in testing_helpers.h, we can use it in other tests and save some lines. Acked-by: David Vernet Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20230515133756.1658301-7-jolsa@kernel.org Signed-off-by: Alexei Starovoitov

selftests/bpf: Move test_progs helpers to testing_helpers object

2023-05-17T05:09:23Z

Moving test_progs helpers to testing_helpers object so they can be used from test_verifier in following changes. Also adding missing ifndef header guard to testing_helpers.h header. Using stderr instead of env.stderr because un/load_bpf_testmod helpers will be used outside test_progs. Also at the point of calling them in test_progs the std files are not hijacked yet and stderr is the same as env.stderr. Acked-by: David Vernet Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20230515133756.1658301-4-jolsa@kernel.org Signed-off-by: Alexei Starovoitov