There are cases where clang compiler is packaged in a way
readelf is a symbolic link to llvm-readelf. In such cases,
llvm-readelf will be used instead of default binutils readelf,
and the following error will appear during libbpf build:
Warning: Num of global symbols in
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/build/libbpf/sharedobjs/libbpf-in.o (367)
does NOT match with num of versioned symbols in
/home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/build/libbpf/libbpf.so libbpf.map (383).
Please make sure all LIBBPF_API symbols are versioned in libbpf.map.
--- /home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/build/libbpf/libbpf_global_syms.tmp ...
+++ /home/yhs/work/bpf-next/tools/testing/selftests/bpf/tools/build/libbpf/libbpf_versioned_syms.tmp ...
@@ -324,6 +324,22 @@
btf__str_by_offset
btf__type_by_id
btf__type_cnt
+LIBBPF_0.0.1
+LIBBPF_0.0.2
+LIBBPF_0.0.3
+LIBBPF_0.0.4
+LIBBPF_0.0.5
+LIBBPF_0.0.6
+LIBBPF_0.0.7
+LIBBPF_0.0.8
+LIBBPF_0.0.9
+LIBBPF_0.1.0
+LIBBPF_0.2.0
+LIBBPF_0.3.0
+LIBBPF_0.4.0
+LIBBPF_0.5.0
+LIBBPF_0.6.0
+LIBBPF_0.7.0
libbpf_attach_type_by_name
libbpf_find_kernel_btf
libbpf_find_vmlinux_btf_id
make[2]: *** [Makefile:184: check_abi] Error 1
make[1]: *** [Makefile:140: all] Error 2
The above failure is due to different printouts for some ABS
versioned symbols. For example, with the same libbpf.so,
$ /bin/readelf --dyn-syms --wide tools/lib/bpf/libbpf.so | grep "LIBBPF" | grep ABS
134: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LIBBPF_0.5.0
202: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LIBBPF_0.6.0
...
$ /opt/llvm/bin/readelf --dyn-syms --wide tools/lib/bpf/libbpf.so | grep "LIBBPF" | grep ABS
134: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LIBBPF_0.5.0@@LIBBPF_0.5.0
202: 0000000000000000 0 OBJECT GLOBAL DEFAULT ABS LIBBPF_0.6.0@@LIBBPF_0.6.0
...
The binutils readelf doesn't print out the symbol LIBBPF_* version and llvm-readelf does.
Such a difference caused libbpf build failure with llvm-readelf.
To fix the issue, let us do proper filtering for LIBBPF_*@@LIBBPF_* symbols.
The proposed fix works for both binutils readelf and llvm-readelf.
Reported-by: Delyan Kratunov <delyank@xxxxxx>
Signed-off-by: Yonghong Song <yhs@xxxxxx>
---
tools/lib/bpf/Makefile | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index f947b61b2107..d1577c26c16b 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -132,7 +132,8 @@ GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \
VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
sed 's/\[.*\]//' | \
awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
- grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
+ grep -Eo '[^ ]+@LIBBPF_' | grep -Ev '^LIBBPF_' | \
+ cut -d@ -f1 | sort -u | wc -l)
CMD_TARGETS = $(LIB_TARGET) $(PC_FILE)
@@ -195,7 +196,8 @@ check_abi: $(OUTPUT)libbpf.so $(VERSION_SCRIPT)
readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
sed 's/\[.*\]//' | \
awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'| \
- grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | \
+ grep -Eo '[^ ]+@LIBBPF_' | grep -Ev '^LIBBPF_' | \
+ cut -d@ -f1 | \
sort -u > $(OUTPUT)libbpf_versioned_syms.tmp; \
diff -u $(OUTPUT)libbpf_global_syms.tmp \
$(OUTPUT)libbpf_versioned_syms.tmp; \
--
2.30.2
