From: Hilko Bengen <bengen@debian.org>
Date: Sun, 02 Dec 2018 23:26:03 +0000
Subject: libbpf: add SONAME to shared object

tools/lib/bpf/libbpf: Add proper version to the shared object.

Add versioning to the shared object to make it easier on distros to
distribute the library without having to watch for API/ABI versioning.

This is similar to the change made to tools/lib/lockdep/Makefile in
be227b45fb228adff4371b8de9e3989904209ff4.

Signed-off-by: Hilko Bengen <bengen@debian.org>
[bwh: Drop unnecessary changes]
---
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -94,7 +94,7 @@ export prefix libdir src obj
 libdir_SQ = $(subst ','\'',$(libdir))
 libdir_relative_SQ = $(subst ','\'',$(libdir_relative))
 
-LIB_FILE = libbpf.a libbpf.so
+LIB_FILE = libbpf.a libbpf.so.$(LIBBPF_VERSION)
 
 VERSION		= $(BPF_VERSION)
 PATCHLEVEL	= $(BPF_PATCHLEVEL)
@@ -103,7 +103,7 @@ EXTRAVERSION	= $(BPF_EXTRAVERSION)
 OBJ		= $@
 N		=
 
-LIBBPF_VERSION = $(BPF_VERSION).$(BPF_PATCHLEVEL).$(BPF_EXTRAVERSION)
+LIBBPF_VERSION = $(shell make --no-print-directory -sC ../../.. kernelversion | cut -d. -f1,2)
 
 # Set compile option CFLAGS
 ifdef EXTRA_CFLAGS
@@ -169,8 +169,8 @@ $(BPF_IN): force elfdep bpfdep
 	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 $^ -o $@
+$(OUTPUT)libbpf.so.$(LIBBPF_VERSION): $(BPF_IN)
+	$(QUIET_LINK)$(CC) --shared $^ -Wl,-soname,$(@F) -o $@
 
 $(OUTPUT)libbpf.a: $(BPF_IN)
 	$(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^
@@ -185,6 +185,7 @@ endef
 install_lib: all_cmd
 	$(call QUIET_INSTALL, $(LIB_FILE)) \
 		$(call do_install,$(LIB_FILE),$(libdir_SQ))
+	$(Q)ln -sf libbpf.so.$(LIBBPF_VERSION) $(DESTDIR_SQ)$(libdir_SQ)/libbpf.so
 
 install_headers:
 	$(call QUIET_INSTALL, headers) \