From: Palmer Dabbelt <palmerdabbelt@google.com>
To: Bjorn Topel <bjorn.topel@gmail.com>
Cc: daniel@iogearbox.net, ast@kernel.org, zlim.lnx@gmail.com,
catalin.marinas@arm.com, will@kernel.org, kafai@fb.com,
songliubraving@fb.com, yhs@fb.com, andriin@fb.com,
shuah@kernel.org, Palmer Dabbelt <palmerdabbelt@google.com>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
clang-built-linux@googlegroups.com, kernel-team@android.com
Subject: [PATCH 1/4] selftests/bpf: Elide a check for LLVM versions that can't compile it
Date: Mon, 27 Jan 2020 18:11:42 -0800 [thread overview]
Message-ID: <20200128021145.36774-2-palmerdabbelt@google.com> (raw)
In-Reply-To: <20200128021145.36774-1-palmerdabbelt@google.com>
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.
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/
Fixes: 20a9ad2e7136 ("selftests/bpf: add CO-RE relocs array tests")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
---
.../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
next prev parent reply other threads:[~2020-01-28 2:14 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-28 2:11 arm64: bpf: Elide some moves to a0 after calls Palmer Dabbelt
2020-01-28 2:11 ` Palmer Dabbelt [this message]
2020-02-11 18:20 ` [PATCH 1/4] selftests/bpf: Elide a check for LLVM versions that can't compile it Nick Desaulniers
2020-01-28 2:11 ` [PATCH 2/4] arm64: bpf: Convert bpf2a64 to a function Palmer Dabbelt
2020-01-28 2:11 ` [PATCH 3/4] arm64: bpf: Split the read and write halves of dst Palmer Dabbelt
2020-01-28 2:11 ` [PATCH 4/4] arm64: bpf: Elide some moves to a0 after calls Palmer Dabbelt
2020-02-04 19:13 ` Björn Töpel
2020-02-11 0:15 ` Alexei Starovoitov
2020-02-04 19:30 ` Björn Töpel
2020-02-04 20:33 ` John Fastabend
2020-02-18 19:28 ` Palmer Dabbelt
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