From 3effc06a4dde3e2f6ee3d82e59d97ec357802a4b Mon Sep 17 00:00:00 2001 From: Jean-Philippe Brucker Date: Wed, 30 Sep 2020 11:36:01 +0200 Subject: [PATCH] selftests/bpf: Fix alignment of .BTF_ids 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 Signed-off-by: Alexei Starovoitov Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20200930093559.2120126-1-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) -- 2.20.1