Re: [PATCH 1/4] selftests/bpf: Elide a check for LLVM versions that can't compile it
From: Nick Desaulniers <ndesaulniers@google.com>
Date: 2020-02-11 18:20:54
Also in:
bpf, linux-kselftest, lkml, netdev
On Mon, Jan 27, 2020 at 6:14 PM 'Palmer Dabbelt' via Clang Built Linux [off-list ref] wrote:
The current stable LLVM BPF backend fails to compile the BPF selftests due to a compiler bug. The bug has been fixed in trunk, but that fix hasn't landed in the binary packages I'm using yet (Fedora arm64). Without this workaround the tests don't compile for me. This patch triggers a preprocessor warning on LLVM versions that definitely have the bug. The test may be conservative (ie, I'm not sure if 9.1 will have the fix), but it should at least make the current set of stable releases work together.
Do older versions of clang still work? Should there be a lower bounds?
quoted hunk ↗ jump to hunk
See https://reviews.llvm.org/D69438 for more information on the fix. I obtained the workaround from https://lore.kernel.org/linux-kselftest/aed8eda7-df20-069b-ea14-f06628984566@gmail.com/T/ (local) Fixes: 20a9ad2e7136 ("selftests/bpf: add CO-RE relocs array tests") Signed-off-by: Palmer Dabbelt <redacted> --- .../testing/selftests/bpf/progs/test_core_reloc_arrays.c | 8 ++++++++ 1 file changed, 8 insertions(+)diff --git a/tools/testing/selftests/bpf/progs/test_core_reloc_arrays.c b/tools/testing/selftests/bpf/progs/test_core_reloc_arrays.c index bf67f0fdf743..c9a3e0585a84 100644 --- a/tools/testing/selftests/bpf/progs/test_core_reloc_arrays.c +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_arrays.c@@ -40,15 +40,23 @@ int test_core_arrays(void *ctx) /* in->a[2] */ if (BPF_CORE_READ(&out->a2, &in->a[2])) return 1; +#if defined(__clang__) && (__clang_major__ < 10) && (__clang_minor__ < 1) +# warning "clang 9.0 SEGVs on multidimensional arrays, see https://reviews.llvm.org/D69438" +#else /* in->b[1][2][3] */ if (BPF_CORE_READ(&out->b123, &in->b[1][2][3])) return 1; +#endif /* in->c[1].c */ if (BPF_CORE_READ(&out->c1c, &in->c[1].c)) return 1; +#if defined(__clang__) && (__clang_major__ < 10) && (__clang_minor__ < 1) +# warning "clang 9.0 SEGVs on multidimensional arrays, see https://reviews.llvm.org/D69438" +#else /* in->d[0][0].d */ if (BPF_CORE_READ(&out->d00d, &in->d[0][0].d)) return 1; +#endif return 0; } --2.25.0.341.g760bfbb309-goog -- You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20200128021145.36774-2-palmerdabbelt%40google.com.
-- Thanks, ~Nick Desaulniers _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel