kernel/linux.git/tools/testing/selftests/bpf/testing_helpers.c, branch v6.18.22

selftests/bpf: Add stress test for rqspinlock in NMI

2025-09-28T10:18:40+00:00

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

2024-10-10T17:44:03+00:00

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: Fix incorrect parameters in NULL pointer checking

2024-08-28T15:44:29+00:00

Smatch reported the following warning: ./tools/testing/selftests/bpf/testing_helpers.c:455 get_xlated_program() warn: variable dereferenced before check 'buf' (see line 454) It seems correct,so let's modify it based on it's suggestion. Actually,commit b23ed4d74c4d ("selftests/bpf: Fix invalid pointer check in get_xlated_program()") fixed an issue in the test_verifier.c once,but it was reverted this time. Let's solve this issue with the minimal changes possible. Reported-by: Dan Carpenter Closes: https://lore.kernel.org/all/1eb3732f-605a-479d-ba64-cd14250cbf91@stanley.mountain/ Fixes: b4b7a4099b8c ("selftests/bpf: Factor out get_xlated_program() helper") Signed-off-by: Hao Ge Link: https://lore.kernel.org/r/20240820023622.29190-1-hao.ge@linux.dev Signed-off-by: Alexei Starovoitov

selftests/bpf: Fix arg parsing in veristat, test_progs

2024-07-30T20:45:44+00:00

Current code parses arguments with strtok_r() using a construct like char *state = NULL; while ((next = strtok_r(state ? NULL : input, ",", &state))) { ... } where logic assumes the 'state' var can distinguish between first and subsequent strtok_r() calls, and adjusts parameters accordingly. However, 'state' is strictly internal context for strtok_r() and no such assumptions are supported in the man page. Moreover, the exact behaviour of 'state' depends on the libc implementation, making the above code fragile. Indeed, invoking "./test_progs -t " on mips64el/musl will hang, with the above code in an infinite loop. Similarly, we see strange behaviour running 'veristat' on mips64el/musl: $ ./veristat -e file,prog,verdict,insns -C two-ok add-failure Can't specify more than 9 stats Rewrite code using a counter to distinguish between strtok_r() calls. Fixes: 61ddff373ffa ("selftests/bpf: Improve by-name subtest selection logic in prog_tests") Fixes: 394169b079b5 ("selftests/bpf: add comparison mode to veristat") Fixes: c8bc5e050976 ("selftests/bpf: Add veristat tool for mass-verifying BPF object files") Signed-off-by: Tony Ambardar Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/392d8bf5559f85fa37926c1494e62312ef252c3d.1722244708.git.tony.ambardar@gmail.com

selftests/bpf: extract utility function for BPF disassembly

2024-07-29T22:05:05+00:00

struct bpf_insn *disasm_insn(struct bpf_insn *insn, char *buf, size_t buf_sz); Disassembles instruction 'insn' to a text buffer 'buf'. Removes insn->code hex prefix added by kernel disassembly routine. Returns a pointer to the next instruction (increments insn by either 1 or 2). Acked-by: Andrii Nakryiko Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20240722233844.1406874-5-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Andrii Nakryiko

selftests/bpf: Fix wq test.

2024-04-24T21:05:05+00:00

The wq test was missing destroy(skel) part which was causing bpf progs to stay loaded. That was causing test_progs to complain with "Failed to unload bpf_testmod.ko from kernel: -11" message, but adding destroy() wasn't enough, since wq callback may be delayed, so loop on unload of bpf_testmod if errno is EAGAIN. Acked-by: Andrii Nakryiko Fixes: 8290dba51910 ("selftests/bpf: wq: add bpf_wq_start() checks") Signed-off-by: Alexei Starovoitov

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

2024-02-22T20:26:41+00:00

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

2024-01-24T04:26:17+00:00

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

2024-01-23T22:40:22+00:00

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

2024-01-23T22:40:21+00:00

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