Re: [PATCH bpf 1/2] bpf, libbpf: fix version info and add it to shared object

[Stanislav Fomichev <sdf@fomichev.me>]

On 03/23, Daniel Borkmann wrote:
> Even though libbpf's versioning script for the linker (libbpf.map)
> is pointing to 0.0.2, the BPF_EXTRAVERSION in the Makefile has
> not been updated along with it and is therefore still on 0.0.1.
> 
> While fixing up, I also noticed that the generated shared object
> versioning information is missing, typical convention is to have
> a linker name (libbpf.so), soname (libbpf.so.0) and real name
> (libbpf.so.0.0.2) for library management. This is based upon the
> LIBBPF_VERSION as well.
> 
> The build will then produce the following bpf libraries:
Thank you for taking care of this! Couple of nits/questions below.

> 
>   # ll libbpf*
>   libbpf.a
>   libbpf.so -> libbpf.so.0.0.2
>   libbpf.so.0 -> libbpf.so.0.0.2
>   libbpf.so.0.0.2
> 
> And the they are also properly installed:
> 
>   # rm -rf /tmp/bld; mkdir /tmp/bld; make -j$(nproc) O=/tmp/bld install
> 
>   Auto-detecting system features:
>   ...                        libelf: [ on  ]
>   ...                           bpf: [ on  ]
> 
>     CC       /tmp/bld/libbpf.o
>     CC       /tmp/bld/bpf.o
>     CC       /tmp/bld/nlattr.o
>     CC       /tmp/bld/btf.o
>     CC       /tmp/bld/libbpf_errno.o
>     CC       /tmp/bld/str_error.o
>     CC       /tmp/bld/netlink.o
>     CC       /tmp/bld/bpf_prog_linfo.o
>     CC       /tmp/bld/libbpf_probes.o
>     CC       /tmp/bld/xsk.o
>     LD       /tmp/bld/libbpf-in.o
>     LINK     /tmp/bld/libbpf.a
>     LINK     /tmp/bld/libbpf.so.0.0.2
>     LINK     /tmp/bld/test_libbpf
>     INSTALL  /tmp/bld/libbpf.a
>     INSTALL  /tmp/bld/libbpf.so.0.0.2
> 
>   # ll /usr/local/lib64/libbpf.*
>   /usr/local/lib64/libbpf.a
>   /usr/local/lib64/libbpf.so -> libbpf.so.0.0.2
>   /usr/local/lib64/libbpf.so.0 -> libbpf.so.0.0.2
>   /usr/local/lib64/libbpf.so.0.0.2
> 
> Fixes: 1bf4b05810fe ("tools: bpftool: add probes for eBPF program types")
> Fixes: 1b76c13e4b36 ("bpf tools: Introduce 'bpf' library and add bpf feature check")
> Reported-by: Stanislav Fomichev <sdf@google.com>
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> ---
>  tools/lib/bpf/Makefile | 42 ++++++++++++++++++++++++++++--------------
>  1 file changed, 28 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index 61aaacf..ada2e90a9 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -3,7 +3,7 @@
>  
>  BPF_VERSION = 0
>  BPF_PATCHLEVEL = 0
> -BPF_EXTRAVERSION = 1
> +BPF_EXTRAVERSION = 2
>  
>  MAKEFLAGS += --no-print-directory
>  
> @@ -79,8 +79,6 @@ export prefix libdir src obj
>  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)
> @@ -88,7 +86,10 @@ EXTRAVERSION	= $(BPF_EXTRAVERSION)
>  OBJ		= $@
>  N		=
>  
> -LIBBPF_VERSION = $(BPF_VERSION).$(BPF_PATCHLEVEL).$(BPF_EXTRAVERSION)
> +LIBBPF_VERSION	= $(BPF_VERSION).$(BPF_PATCHLEVEL).$(BPF_EXTRAVERSION)
> +
> +LIB_TARGET	= libbpf.a libbpf.so.$(LIBBPF_VERSION)
> +LIB_FILE	= libbpf.a libbpf.so*
>  
>  # Set compile option CFLAGS
>  ifdef EXTRA_CFLAGS
> @@ -128,16 +129,18 @@ 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
> +BPF_IN		:= $(OUTPUT)libbpf-in.o
> +VERSION_SCRIPT	:= libbpf.map
> +
> +LIB_TARGET	:= $(addprefix $(OUTPUT),$(LIB_TARGET))
> +LIB_FILE	:= $(addprefix $(OUTPUT),$(LIB_FILE))
>  
>  GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN) | \
>  			   awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {s++} END{print s}')
>  VERSIONED_SYM_COUNT = $(shell readelf -s --wide $(OUTPUT)libbpf.so | \
>  			      grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
>  
> -CMD_TARGETS = $(LIB_FILE)
> +CMD_TARGETS = $(LIB_TARGET)
>  
>  CXX_TEST_TARGET = $(OUTPUT)test_libbpf
>  
> @@ -170,9 +173,13 @@ $(BPF_IN): force elfdep bpfdep
>  	echo "Warning: Kernel ABI header at 'tools/include/uapi/linux/if_xdp.h' differs from latest version at 'include/uapi/linux/if_xdp.h'" >&2 )) || true
>  	$(Q)$(MAKE) $(build)=libbpf
>  
> -$(OUTPUT)libbpf.so: $(BPF_IN)
> -	$(QUIET_LINK)$(CC) --shared -Wl,--version-script=$(VERSION_SCRIPT) \
> -		$^ -o $@
> +$(OUTPUT)libbpf.so: $(OUTPUT)libbpf.so.$(LIBBPF_VERSION)
> +
> +$(OUTPUT)libbpf.so.$(LIBBPF_VERSION): $(BPF_IN)
> +	$(QUIET_LINK)$(CC) --shared -Wl,-soname,libbpf.so.$(LIBBPF_VERSION) \
Shouldn't it be -soname,libbpf.so.$(VERSION) ?

> +				    -Wl,--version-script=$(VERSION_SCRIPT) $^ -o $@
> +	@ln -sf $(@F) $(OUTPUT)libbpf.so
> +	@ln -sf $(@F) $(OUTPUT)libbpf.so.$(VERSION)
>  
>  $(OUTPUT)libbpf.a: $(BPF_IN)
>  	$(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^
> @@ -192,6 +199,12 @@ check_abi: $(OUTPUT)libbpf.so
>  		exit 1;							 \
>  	fi
>  
> +define do_install_mkdir
> +	if [ ! -d '$(DESTDIR_SQ)$1' ]; then		\
> +		$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$1';	\
> +	fi
> +endef
> +
>  define do_install
>  	if [ ! -d '$(DESTDIR_SQ)$2' ]; then		\
>  		$(INSTALL) -d -m 755 '$(DESTDIR_SQ)$2';	\
> @@ -200,8 +213,9 @@ define do_install
>  endef
>  
>  install_lib: all_cmd
> -	$(call QUIET_INSTALL, $(LIB_FILE)) \
> -		$(call do_install,$(LIB_FILE),$(libdir_SQ))
> +	$(call QUIET_INSTALL, $(LIB_TARGET)) \
> +		$(call do_install_mkdir,$(libdir_SQ)); \
> +		cp -fpR $(LIB_FILE) $(DESTDIR)$(libdir_SQ)
>  
>  install_headers:
>  	$(call QUIET_INSTALL, headers) \
> @@ -219,7 +233,7 @@ config-clean:
>  
>  clean:
>  	$(call QUIET_CLEAN, libbpf) $(RM) $(TARGETS) $(CXX_TEST_TARGET) \
> -		*.o *~ *.a *.so .*.d .*.cmd LIBBPF-CFLAGS
> +		*.o *~ *.a *.so *.so.$(VERSION) .*.d .*.cmd LIBBPF-CFLAGS
What about libbpf.so.$(LIBBPF_VERSION) ?

>  	$(call QUIET_CLEAN, core-gen) $(RM) $(OUTPUT)FEATURE-DUMP.libbpf
>  
>  
> -- 
> 2.9.5
>