path: root/tools
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authorAndrey Ignatov <rdna@fb.com>2018-11-23 16:44:34 -0800
committerAlexei Starovoitov <ast@kernel.org>2018-11-26 18:57:14 -0800
commit306b267cb3c4c2a3d12138041fed10478804da82 (patch)
treef6e05c4f5e0bbe196ba95db92615597a15e509ae /tools
parentlibbpf: Add version script for DSO (diff)
libbpf: Verify versioned symbols
Since ABI versioning info is kept separately from the code it's easy to forget to update it while adding a new API. Add simple verification that all global symbols exported with LIBBPF_API are versioned in libbpf.map version script. The idea is to check that number of global symbols in libbpf-in.o, that is the input to the linker, matches with number of unique versioned symbols in libbpf.so, that is the output of the linker. If these numbers don't match, it may mean some symbol was not versioned and make will fail. "Unique" means that if a symbol is present in more than one version of ABI due to ABI changes, it'll be counted once. Another option to calculate number of global symbols in the "input" could be to count number of LIBBPF_ABI entries in C headers but it seems to be fragile. Example of output when a symbol is missing in version script: ... LD libbpf-in.o LINK libbpf.a LINK libbpf.so Warning: Num of global symbols in libbpf-in.o (115) does NOT match with num of versioned symbols in libbpf.so (114). Please make sure all LIBBPF_API symbols are versioned in libbpf.map. make: *** [check_abi] Error 1 Signed-off-by: Andrey Ignatov <rdna@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools')
1 files changed, 18 insertions, 1 deletions
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 22c5ffe22825..34d9c3619c96 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -147,6 +147,11 @@ BPF_IN := $(OUTPUT)libbpf-in.o
LIB_FILE := $(addprefix $(OUTPUT),$(LIB_FILE))
VERSION_SCRIPT := libbpf.map
+GLOBAL_SYM_COUNT = $(shell readelf -s $(BPF_IN) | \
+ awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {s++} END{print s}')
+VERSIONED_SYM_COUNT = $(shell readelf -s $(OUTPUT)libbpf.so | \
+ grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
CXX_TEST_TARGET = $(OUTPUT)test_libbpf
@@ -159,7 +164,7 @@ TARGETS = $(CMD_TARGETS)
all: fixdep all_cmd
-all_cmd: $(CMD_TARGETS)
+all_cmd: $(CMD_TARGETS) check
$(BPF_IN): force elfdep bpfdep
@(test -f ../../include/uapi/linux/bpf.h -a -f ../../../include/uapi/linux/bpf.h && ( \
@@ -186,6 +191,18 @@ $(OUTPUT)libbpf.a: $(BPF_IN)
$(OUTPUT)test_libbpf: test_libbpf.cpp $(OUTPUT)libbpf.a
$(QUIET_LINK)$(CXX) $^ -lelf -o $@
+check: check_abi
+check_abi: $(OUTPUT)libbpf.so
+ @if [ "$(GLOBAL_SYM_COUNT)" != "$(VERSIONED_SYM_COUNT)" ]; then \
+ echo "Warning: Num of global symbols in $(BPF_IN)" \
+ "($(GLOBAL_SYM_COUNT)) does NOT match with num of" \
+ "versioned symbols in $^ ($(VERSIONED_SYM_COUNT))." \
+ "Please make sure all LIBBPF_API symbols are" \
+ "versioned in $(VERSION_SCRIPT)." >&2; \
+ exit 1; \
+ fi
define do_install
if [ ! -d '$(DESTDIR_SQ)$2' ]; then \
$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$2'; \