Record which built-ins are optional and needed for some of recent BPF CO-RE subtests. Document Clang diff that fixed corner-case issue with __builtin_btf_type_id().
Suggested-by: Alexei Starovoitov <a...@kernel.org> Signed-off-by: Andrii Nakryiko <andr...@fb.com> --- tools/testing/selftests/bpf/README.rst | 21 +++++++++++++++++++ .../bpf/progs/test_core_reloc_type_id.c | 4 +++- 2 files changed, 24 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/README.rst b/tools/testing/selftests/bpf/README.rst index e885d351595f..66acfcf15ff2 100644 --- a/tools/testing/selftests/bpf/README.rst +++ b/tools/testing/selftests/bpf/README.rst @@ -43,3 +43,24 @@ This is due to a llvm BPF backend bug. The fix https://reviews.llvm.org/D78466 has been pushed to llvm 10.x release branch and will be available in 10.0.1. The fix is available in llvm 11.0.0 trunk. + +BPF CO-RE-based tests and Clang version +======================================= + +A set of selftests use BPF target-specific built-ins, which might require +bleeding-edge Clang versions (Clang 12 nightly at this time). + +Few sub-tests of core_reloc test suit (part of test_progs test runner) require +the following built-ins, listed with corresponding Clang diffs introducing +them to Clang/LLVM. These sub-tests are going to be skipped if Clang is too +old to support them, they shouldn't cause build failures or runtime test +failures: + + - __builtin_btf_type_id() ([0], [1], [2]); + - __builtin_preserve_type_info(), __builtin_preserve_enum_value() ([3], [4]). + + [0] https://reviews.llvm.org/D74572 + [1] https://reviews.llvm.org/D74668 + [2] https://reviews.llvm.org/D85174 + [3] https://reviews.llvm.org/D83878 + [4] https://reviews.llvm.org/D83242 diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_type_id.c b/tools/testing/selftests/bpf/progs/test_core_reloc_type_id.c index 23e6e6bf276c..22aba3f6e344 100644 --- a/tools/testing/selftests/bpf/progs/test_core_reloc_type_id.c +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_type_id.c @@ -75,10 +75,12 @@ int test_core_type_id(void *ctx) { /* We use __builtin_btf_type_id() in this tests, but up until the time * __builtin_preserve_type_info() was added it contained a bug that - * would make this test fail. The bug was fixed with addition of + * would make this test fail. The bug was fixed ([0]) with addition of * __builtin_preserve_type_info(), though, so that's what we are using * to detect whether this test has to be executed, however strange * that might look like. + * + * [0] https://reviews.llvm.org/D85174 */ #if __has_builtin(__builtin_preserve_type_info) struct core_reloc_type_id_output *out = (void *)&data.out; -- 2.24.1
