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| author |   Yonghong Song <yhs@fb.com> | 2020-05-13 11:02:15 -0700 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2020-05-13 12:30:49 -0700 |
| commit | 99aaf53e2f7c4a1b152b7f300c6b07ffbc2fe192 (patch) | |
| tree | 5fa064c03afbcde41ec88725b0bb720be64eb55c /tools/testing/selftests/bpf/README.rst | |
| parent | Merge branch 'benchmark-runner' (diff) | |
| download | linux-dev-99aaf53e2f7c4a1b152b7f300c6b07ffbc2fe192.tar.xz linux-dev-99aaf53e2f7c4a1b152b7f300c6b07ffbc2fe192.zip | |
tools/bpf: selftests : Explain bpf_iter test failures with llvm 10.0.0
Commit 6879c042e105 ("tools/bpf: selftests: Add bpf_iter selftests")
added self tests for bpf_iter feature. But two subtests
ipv6_route and netlink needs llvm latest 10.x release branch
or trunk due to a bug in llvm BPF backend. This patch added
the file README.rst to document these two failures
so people using llvm 10.0.0 can be aware of them.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200513180215.2949237-1-yhs@fb.com
Diffstat (limited to 'tools/testing/selftests/bpf/README.rst')
| -rw-r--r-- | tools/testing/selftests/bpf/README.rst | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/README.rst b/tools/testing/selftests/bpf/README.rst new file mode 100644 index 000000000000..0f67f1b470b0 --- /dev/null +++ b/tools/testing/selftests/bpf/README.rst @@ -0,0 +1,43 @@ +================== +BPF Selftest Notes +================== + +Additional information about selftest failures are +documented here. + +bpf_iter test failures with clang/llvm 10.0.0 +============================================= + +With clang/llvm 10.0.0, the following two bpf_iter tests failed: + * ``bpf_iter/ipv6_route`` + * ``bpf_iter/netlink`` + +The symptom for ``bpf_iter/ipv6_route`` looks like + +.. code-block:: c + + 2: (79) r8 = *(u64 *)(r1 +8) + ... + 14: (bf) r2 = r8 + 15: (0f) r2 += r1 + ; BPF_SEQ_PRINTF(seq, "%pi6 %02x ", &rt->fib6_dst.addr, rt->fib6_dst.plen); + 16: (7b) *(u64 *)(r8 +64) = r2 + only read is supported + +The symptom for ``bpf_iter/netlink`` looks like + +.. code-block:: c + + ; struct netlink_sock *nlk = ctx->sk; + 2: (79) r7 = *(u64 *)(r1 +8) + ... + 15: (bf) r2 = r7 + 16: (0f) r2 += r1 + ; BPF_SEQ_PRINTF(seq, "%pK %-3d ", s, s->sk_protocol); + 17: (7b) *(u64 *)(r7 +0) = r2 + only read is supported + +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. |