[PATCH 5.14 216/334] libbpf: Re-build libbpf.so when libbpf.map changes

Greg Kroah-Hartman
2021-09-13T14:40:31Z

From: Andrii Nakryiko <andrii@kernel.org>

[ Upstream commit 61c7aa5020e98ac2fdcf07d07eec1baf2e9f0a08 ]

Ensure libbpf.so is re-built whenever libbpf.map is modified. Without this,
changes to libbpf.map are not detected and versioned symbols mismatch error
will be reported until `make clean && make` is used, which is a suboptimal
developer experience.

Fixes: 306b267cb3c4 ("libbpf: Verify versioned symbols")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210815070609.987780-8-andrii@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/lib/bpf/Makefile | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index ec14aa725bb0..74c3b73a5fbe 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -4,8 +4,9 @@
RM ?= rm
srctree = $(abs_srctree)

+VERSION_SCRIPT := libbpf.map
LIBBPF_VERSION := $(shell \
- grep -oE '^LIBBPF_([0-9.]+)' libbpf.map | \
+ grep -oE '^LIBBPF_([0-9.]+)' $(VERSION_SCRIPT) | \
sort -rV | head -n1 | cut -d'_' -f2)
LIBBPF_MAJOR_VERSION := $(firstword $(subst ., ,$(LIBBPF_VERSION)))

@@ -110,7 +111,6 @@ SHARED_OBJDIR := $(OUTPUT)sharedobjs/
STATIC_OBJDIR := $(OUTPUT)staticobjs/
BPF_IN_SHARED := $(SHARED_OBJDIR)libbpf-in.o
BPF_IN_STATIC := $(STATIC_OBJDIR)libbpf-in.o
-VERSION_SCRIPT := libbpf.map
BPF_HELPER_DEFS := $(OUTPUT)bpf_helper_defs.h

LIB_TARGET := $(addprefix $(OUTPUT),$(LIB_TARGET))
@@ -163,10 +163,10 @@ $(BPF_HELPER_DEFS): $(srctree)/tools/include/uapi/linux/bpf.h

$(OUTPUT)libbpf.so: $(OUTPUT)libbpf.so.$(LIBBPF_VERSION)

-$(OUTPUT)libbpf.so.$(LIBBPF_VERSION): $(BPF_IN_SHARED)
+$(OUTPUT)libbpf.so.$(LIBBPF_VERSION): $(BPF_IN_SHARED) $(VERSION_SCRIPT)
$(QUIET_LINK)$(CC) $(LDFLAGS) \
--shared -Wl,-soname,libbpf.so.$(LIBBPF_MAJOR_VERSION) \
- -Wl,--version-script=$(VERSION_SCRIPT) $^ -lelf -lz -o $@
+ -Wl,--version-script=$(VERSION_SCRIPT) $< -lelf -lz -o $@
@ln -sf $(@F) $(OUTPUT)libbpf.so
@ln -sf $(@F) $(OUTPUT)libbpf.so.$(LIBBPF_MAJOR_VERSION)

@@ -181,7 +181,7 @@ $(OUTPUT)libbpf.pc:

check: check_abi

-check_abi: $(OUTPUT)libbpf.so
+check_abi: $(OUTPUT)libbpf.so $(VERSION_SCRIPT)
@if [ "$(GLOBAL_SYM_COUNT)" != "$(VERSIONED_SYM_COUNT)" ]; then \
echo "Warning: Num of global symbols in $(BPF_IN_SHARED)" \
"($(GLOBAL_SYM_COUNT)) does NOT match with num of" \
--
2.30.2