libbpf: Use .so dynamic symbols for abi check

Since dynamic symbols are used for dynamic linking it makes sense to
use them (readelf --dyn-syms) for abi check.

Found with some configuration on powerpc where linker puts
local *.plt_call.* symbols into .so.

Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200525061846.16524-1-yauheni.kaliuta@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index d02c4d9..bf8ed13 100644 (file)
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -151,7 +151,7 @@ GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \
                           sed 's/\[.*\]//' | \
                           awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
                           sort -u | wc -l)
-VERSIONED_SYM_COUNT = $(shell readelf -s --wide $(OUTPUT)libbpf.so | \
+VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
                              grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
 
 CMD_TARGETS = $(LIB_TARGET) $(PC_FILE)
@@ -218,7 +218,7 @@ check_abi: $(OUTPUT)libbpf.so
                    sed 's/\[.*\]//' |                                   \
                    awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'|  \
                    sort -u > $(OUTPUT)libbpf_global_syms.tmp;           \
-               readelf -s --wide $(OUTPUT)libbpf.so |                   \
+               readelf --dyn-syms --wide $(OUTPUT)libbpf.so |           \
                    grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 |             \
                    sort -u > $(OUTPUT)libbpf_versioned_syms.tmp;        \
                diff -u $(OUTPUT)libbpf_global_syms.tmp                  \