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linux-next/tools/lib/bpf/Makefile
Andrey Ignatov 306b267cb3 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>
2018-11-26 18:57:14 -08:00

250 lines
7.3 KiB
Makefile
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# SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
# Most of this file is copied from tools/lib/traceevent/Makefile
BPF_VERSION = 0
BPF_PATCHLEVEL = 0
BPF_EXTRAVERSION = 1
MAKEFLAGS += --no-print-directory
ifeq ($(srctree),)
srctree := $(patsubst %/,%,$(dir $(CURDIR)))
srctree := $(patsubst %/,%,$(dir $(srctree)))
srctree := $(patsubst %/,%,$(dir $(srctree)))
#$(info Determined 'srctree' to be $(srctree))
endif
# Makefiles suck: This macro sets a default value of $(2) for the
# variable named by $(1), unless the variable has been set by
# environment or command line. This is necessary for CC and AR
# because make sets default values, so the simpler ?= approach
# won't work as expected.
define allow-override
$(if $(or $(findstring environment,$(origin $(1))),\
$(findstring command line,$(origin $(1)))),,\
$(eval $(1) = $(2)))
endef
# Allow setting CC and AR, or setting CROSS_COMPILE as a prefix.
$(call allow-override,CC,$(CROSS_COMPILE)gcc)
$(call allow-override,AR,$(CROSS_COMPILE)ar)
INSTALL = install
# Use DESTDIR for installing into a different root directory.
# This is useful for building a package. The program will be
# installed in this directory as if it was the root directory.
# Then the build tool can move it later.
DESTDIR ?=
DESTDIR_SQ = '$(subst ','\'',$(DESTDIR))'
include $(srctree)/tools/scripts/Makefile.arch
ifeq ($(LP64), 1)
libdir_relative = lib64
else
libdir_relative = lib
endif
prefix ?= /usr/local
libdir = $(prefix)/$(libdir_relative)
man_dir = $(prefix)/share/man
man_dir_SQ = '$(subst ','\'',$(man_dir))'
export man_dir man_dir_SQ INSTALL
export DESTDIR DESTDIR_SQ
include ../../scripts/Makefile.include
# copy a bit from Linux kbuild
ifeq ("$(origin V)", "command line")
VERBOSE = $(V)
endif
ifndef VERBOSE
VERBOSE = 0
endif
FEATURE_USER = .libbpf
FEATURE_TESTS = libelf libelf-mmap bpf reallocarray cxx
FEATURE_DISPLAY = libelf bpf
INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi
FEATURE_CHECK_CFLAGS-bpf = $(INCLUDES)
check_feat := 1
NON_CHECK_FEAT_TARGETS := clean TAGS tags cscope help
ifdef MAKECMDGOALS
ifeq ($(filter-out $(NON_CHECK_FEAT_TARGETS),$(MAKECMDGOALS)),)
check_feat := 0
endif
endif
ifeq ($(check_feat),1)
ifeq ($(FEATURES_DUMP),)
include $(srctree)/tools/build/Makefile.feature
else
include $(FEATURES_DUMP)
endif
endif
export prefix libdir src obj
# Shell quotes
libdir_SQ = $(subst ','\'',$(libdir))
libdir_relative_SQ = $(subst ','\'',$(libdir_relative))
LIB_FILE = libbpf.a libbpf.so
VERSION = $(BPF_VERSION)
PATCHLEVEL = $(BPF_PATCHLEVEL)
EXTRAVERSION = $(BPF_EXTRAVERSION)
OBJ = $@
N =
LIBBPF_VERSION = $(BPF_VERSION).$(BPF_PATCHLEVEL).$(BPF_EXTRAVERSION)
# Set compile option CFLAGS
ifdef EXTRA_CFLAGS
CFLAGS := $(EXTRA_CFLAGS)
else
CFLAGS := -g -Wall
endif
ifeq ($(feature-libelf-mmap), 1)
override CFLAGS += -DHAVE_LIBELF_MMAP_SUPPORT
endif
ifeq ($(feature-reallocarray), 0)
override CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
endif
# Append required CFLAGS
override CFLAGS += $(EXTRA_WARNINGS)
override CFLAGS += -Werror -Wall
override CFLAGS += -fPIC
override CFLAGS += $(INCLUDES)
override CFLAGS += -fvisibility=hidden
ifeq ($(VERBOSE),1)
Q =
else
Q = @
endif
# Disable command line variables (CFLAGS) override from top
# level Makefile (perf), otherwise build Makefile will get
# the same command line setup.
MAKEOVERRIDES=
all:
export srctree OUTPUT CC LD CFLAGS V
include $(srctree)/tools/build/Makefile.include
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)
CMD_TARGETS = $(LIB_FILE)
CXX_TEST_TARGET = $(OUTPUT)test_libbpf
ifeq ($(feature-cxx), 1)
CMD_TARGETS += $(CXX_TEST_TARGET)
endif
TARGETS = $(CMD_TARGETS)
all: fixdep all_cmd
all_cmd: $(CMD_TARGETS) check
$(BPF_IN): force elfdep bpfdep
@(test -f ../../include/uapi/linux/bpf.h -a -f ../../../include/uapi/linux/bpf.h && ( \
(diff -B ../../include/uapi/linux/bpf.h ../../../include/uapi/linux/bpf.h >/dev/null) || \
echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf.h' differs from latest version at 'include/uapi/linux/bpf.h'" >&2 )) || true
@(test -f ../../include/uapi/linux/bpf_common.h -a -f ../../../include/uapi/linux/bpf_common.h && ( \
(diff -B ../../include/uapi/linux/bpf_common.h ../../../include/uapi/linux/bpf_common.h >/dev/null) || \
echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/bpf_common.h' differs from latest version at 'include/uapi/linux/bpf_common.h'" >&2 )) || true
@(test -f ../../include/uapi/linux/netlink.h -a -f ../../../include/uapi/linux/netlink.h && ( \
(diff -B ../../include/uapi/linux/netlink.h ../../../include/uapi/linux/netlink.h >/dev/null) || \
echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/netlink.h' differs from latest version at 'include/uapi/linux/netlink.h'" >&2 )) || true
@(test -f ../../include/uapi/linux/if_link.h -a -f ../../../include/uapi/linux/if_link.h && ( \
(diff -B ../../include/uapi/linux/if_link.h ../../../include/uapi/linux/if_link.h >/dev/null) || \
echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/if_link.h' differs from latest version at 'include/uapi/linux/if_link.h'" >&2 )) || true
$(Q)$(MAKE) $(build)=libbpf
$(OUTPUT)libbpf.so: $(BPF_IN)
$(QUIET_LINK)$(CC) --shared -Wl,--version-script=$(VERSION_SCRIPT) \
$^ -o $@
$(OUTPUT)libbpf.a: $(BPF_IN)
$(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^
$(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'; \
fi; \
$(INSTALL) $1 $(if $3,-m $3,) '$(DESTDIR_SQ)$2'
endef
install_lib: all_cmd
$(call QUIET_INSTALL, $(LIB_FILE)) \
$(call do_install,$(LIB_FILE),$(libdir_SQ))
install_headers:
$(call QUIET_INSTALL, headers) \
$(call do_install,bpf.h,$(prefix)/include/bpf,644); \
$(call do_install,libbpf.h,$(prefix)/include/bpf,644);
$(call do_install,btf.h,$(prefix)/include/bpf,644);
install: install_lib
### Cleaning rules
config-clean:
$(call QUIET_CLEAN, config)
$(Q)$(MAKE) -C $(srctree)/tools/build/feature/ clean >/dev/null
clean:
$(call QUIET_CLEAN, libbpf) $(RM) $(TARGETS) $(CXX_TEST_TARGET) \
*.o *~ *.a *.so .*.d .*.cmd LIBBPF-CFLAGS
$(call QUIET_CLEAN, core-gen) $(RM) $(OUTPUT)FEATURE-DUMP.libbpf
PHONY += force elfdep bpfdep
force:
elfdep:
@if [ "$(feature-libelf)" != "1" ]; then echo "No libelf found"; exit 1 ; fi
bpfdep:
@if [ "$(feature-bpf)" != "1" ]; then echo "BPF API too old"; exit 1 ; fi
# Declare the contents of the .PHONY variable as phony. We keep that
# information in a variable so we can use it in if_changed and friends.
.PHONY: $(PHONY)
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