From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: ast@kernel.org, daniel@iogearbox.net
Cc: shuah@kernel.org, kafai@fb.com, songliubraving@fb.com,
yhs@fb.com, andriin@fb.com, john.fastabend@gmail.com,
kpsingh@chromium.org, jolsa@kernel.org, bpf@vger.kernel.org,
Jean-Philippe Brucker <jean-philippe@linaro.org>
Subject: [PATCH bpf-next] selftests/bpf: Fix alignment of .BTF_ids
Date: Wed, 30 Sep 2020 11:36:01 +0200 [thread overview]
Message-ID: <20200930093559.2120126-1-jean-philippe@linaro.org> (raw)
Fix a build failure on arm64, due to missing alignment information for
the .BTF_ids section:
resolve_btfids.test.o: in function `test_resolve_btfids':
tools/testing/selftests/bpf/prog_tests/resolve_btfids.c:140:(.text+0x29c): relocation truncated to fit: R_AARCH64_LDST32_ABS_LO12_NC against `.BTF_ids'
ld: tools/testing/selftests/bpf/prog_tests/resolve_btfids.c:140: warning: one possible cause of this error is that the symbol is being referenced in the indicated code as if it had a larger alignment than was declared where it was defined
In vmlinux, the .BTF_ids section is aligned to 4 bytes by vmlinux.lds.h.
In test_progs however, .BTF_ids doesn't have alignment constraints. The
arm64 linker expects the btf_id_set.cnt symbol, a u32, to be naturally
aligned but finds it misaligned and cannot apply the relocation. Enforce
alignment of .BTF_ids to 4 bytes.
Fixes: cd04b04de119 ("selftests/bpf: Add set test to resolve_btfids")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
tools/testing/selftests/bpf/prog_tests/resolve_btfids.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c b/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c
index 8826c652adad..6ace5e9efec1 100644
--- a/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c
+++ b/tools/testing/selftests/bpf/prog_tests/resolve_btfids.c
@@ -28,6 +28,12 @@ struct symbol test_symbols[] = {
{ "func", BTF_KIND_FUNC, -1 },
};
+/* Align the .BTF_ids section to 4 bytes */
+asm (
+".pushsection " BTF_IDS_SECTION " ,\"a\"; \n"
+".balign 4, 0; \n"
+".popsection; \n");
+
BTF_ID_LIST(test_list_local)
BTF_ID_UNUSED
BTF_ID(typedef, S)
--
2.28.0
next reply other threads:[~2020-09-30 9:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-30 9:36 Jean-Philippe Brucker [this message]
2020-09-30 11:52 ` [PATCH bpf-next] selftests/bpf: Fix alignment of .BTF_ids Jiri Olsa
2020-10-01 1:30 ` patchwork-bot+bpf
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