tools/libbpf: Avoid counting local symbols in ABI check

Encountered the following failure building libbpf from kernel 5.8.5 sources with GCC 8.4.0 and binutils 2.34: (long paths shortened) Warning: Num of global symbols in sharedobjs/libbpf-in.o (234) does NOT match with num of versioned symbols in libbpf.so (236). Please make sure all LIBBPF_API symbols are versioned in libbpf.map. --- libbpf_global_syms.tmp 2020-09-02 07:30:58.920084380 +0000 +++ libbpf_versioned_syms.tmp 2020-09-02 07:30:58.924084388 +0000 @@ -1,3 +1,5 @@ +_fini +_init bpf_btf_get_fd_by_id bpf_btf_get_next_id bpf_create_map make[4]: *** [Makefile:210: check_abi] Error 1 Investigation shows _fini and _init are actually local symbols counted amongst global ones: $ readelf --dyn-syms --wide libbpf.so|head -10 Symbol table '.dynsym' contains 343 entries: Num: Value Size Type Bind Vis Ndx Name 0: 00000000 0 NOTYPE LOCAL DEFAULT UND 1: 00004098 0 SECTION LOCAL DEFAULT 11 2: 00004098 8 FUNC LOCAL DEFAULT 11 _init@@LIBBPF_0.0.1 3: 00023040 8 FUNC LOCAL DEFAULT 14 _fini@@LIBBPF_0.0.1 4: 00000000 0 OBJECT GLOBAL DEFAULT ABS LIBBPF_0.0.4 5: 00000000 0 OBJECT GLOBAL DEFAULT ABS LIBBPF_0.0.1 6: 0000ffa4 8 FUNC GLOBAL DEFAULT 12 bpf_object__find_map_by_offset@@LIBBPF_0.0.1 A previous commit filtered global symbols in sharedobjs/libbpf-in.o. Do the same with the libbpf.so DSO for consistent comparison. Fixes: 306b267 ("libbpf: Verify versioned symbols") Signed-off-by: Tony Ambardar <Tony.Ambardar@gmail.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Andrii Nakryiko <andriin@fb.com> Link: https://lore.kernel.org/bpf/20200905214831.1565465-1-Tony.Ambardar@gmail.com

Author: guidosarducci

tools/lib/bpf/Makefile

@@ -152,6 +152,7 @@ GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \
  awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
  sort -u | wc -l)
 VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
+ awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
  grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
 
 CMD_TARGETS = $(LIB_TARGET) $(PC_FILE)
@@ -219,6 +220,7 @@ check_abi: $(OUTPUT)libbpf.so
  awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'| \
  sort -u > $(OUTPUT)libbpf_global_syms.tmp; \
 readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
+ awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'| \
  grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | \
  sort -u > $(OUTPUT)libbpf_versioned_syms.tmp; \
 diff -u $(OUTPUT)libbpf_global_syms.tmp \