iproute2: support eBFP/XDP object file loading, simplify linking libelf

Add build and runtime dependencies on libelf, allowing tc and ip-full
to load BPF and XDP object files respectively.

Define package 'tc' as a singleton package variant, which can be used to
enable additional functionality limited only to tc. Also set ip-tiny
as the default 'ip' variant.

Preserve optionality of libelf by having configuration script follow the
HAVE_ELF environment variable, used similarly to the HAVE_MNL variable.

Signed-off-by: Tony Ambardar <itugrok@yahoo.com>

package/network/utils/iproute2/Makefile

@@ -37,6 +37,7 @@ define Package/ip-tiny
 $(call Package/iproute2/Default)
  TITLE:=Routing control utility (Minimal)
  VARIANT:=tiny
+ DEFAULT_VARIANT:=1
  PROVIDES:=ip
  ALTERNATIVES:=200:/sbin/ip:/usr/libexec/ip-tiny
  DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl
@@ -48,55 +49,65 @@ $(call Package/iproute2/Default)
  VARIANT:=full
  PROVIDES:=ip
  ALTERNATIVES:=300:/sbin/ip:/usr/libexec/ip-full
- DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl
+ DEPENDS:=+libnl-tiny +libelf +(PACKAGE_devlink||PACKAGE_rdma):libmnl
 endef
 
 define Package/tc
 $(call Package/iproute2/Default)
   TITLE:=Traffic control utility
+  VARIANT:=tc
+  PROVIDES:=tc
   DEPENDS:=+kmod-sched-core +libxtables +libelf +(PACKAGE_devlink||PACKAGE_rdma):libmnl
 endef
 
 define Package/genl
 $(call Package/iproute2/Default)
   TITLE:=General netlink utility frontend
-  DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl
+  DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl +(PACKAGE_tc||PACKAGE_ip-full):libelf
 endef
 
 define Package/ip-bridge
 $(call Package/iproute2/Default)
   TITLE:=Bridge configuration utility from iproute2
-  DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl
+  DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl +(PACKAGE_tc||PACKAGE_ip-full):libelf
 endef
 
 define Package/ss
 $(call Package/iproute2/Default)
   TITLE:=Socket statistics utility
-  DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl
+  DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl +(PACKAGE_tc||PACKAGE_ip-full):libelf
 endef
 
 define Package/nstat
 $(call Package/iproute2/Default)
   TITLE:=Network statistics utility
-  DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl
+  DEPENDS:=+libnl-tiny +(PACKAGE_devlink||PACKAGE_rdma):libmnl +(PACKAGE_tc||PACKAGE_ip-full):libelf
 endef
 
 define Package/devlink
 $(call Package/iproute2/Default)
   TITLE:=Network devlink utility
-  DEPENDS:=+libmnl
+  DEPENDS:=+libmnl +(PACKAGE_tc||PACKAGE_ip-full):libelf
 endef
 
 define Package/rdma
 $(call Package/iproute2/Default)
   TITLE:=Network rdma utility
-  DEPENDS:=+libmnl
+  DEPENDS:=+libmnl +(PACKAGE_tc||PACKAGE_ip-full):libelf
 endef
 
 ifeq ($(BUILD_VARIANT),tiny)
   IP_CONFIG_TINY:=y
 endif
 
+ifeq ($(BUILD_VARIANT),full)
+  HAVE_ELF:=y
+endif
+
+ifeq ($(BUILD_VARIANT),tc)
+  HAVE_ELF:=y
+endif
+
 ifdef CONFIG_PACKAGE_devlink
   HAVE_MNL:=y
 endif
@@ -118,6 +129,7 @@ MAKE_FLAGS += \
 	KERNEL_INCLUDE="$(LINUX_DIR)/user_headers/include" \
 	SHARED_LIBS="" \
 	IP_CONFIG_TINY=$(IP_CONFIG_TINY) \
+	HAVE_ELF=$(HAVE_ELF) \
 	HAVE_MNL=$(HAVE_MNL) \
 	IPT_LIB_DIR=/usr/lib/iptables \
 	XT_LIB_DIR=/usr/lib/iptables \

package/network/utils/iproute2/patches/145-keep_libelf_optional.patch

@@ -0,0 +1,11 @@
+--- a/configure
++++ b/configure
+@@ -228,7 +228,7 @@ EOF
+ 
+ check_elf()
+ {
+-    if ${PKG_CONFIG} libelf --exists; then
++    if [ "${HAVE_ELF}" = "y" ] && ${PKG_CONFIG} libelf --exists; then
+ 	echo "HAVE_ELF:=y" >>$CONFIG
+ 	echo "yes"
+ 

package/network/utils/iproute2/patches/190-link-libelf-to-tc-only.patch

@@ -1,60 +0,0 @@
---- a/configure
-+++ b/configure
-@@ -231,8 +231,9 @@ check_elf()
- 	echo "HAVE_ELF:=y" >>$CONFIG
- 	echo "yes"
- 
--	echo 'CFLAGS += -DHAVE_ELF' `${PKG_CONFIG} libelf --cflags` >> $CONFIG
--	echo 'LDLIBS += ' `${PKG_CONFIG} libelf --libs` >>$CONFIG
-+	echo 'CFLAGS += -DHAVE_ELF' >> $CONFIG
-+	echo 'ELF_CFLAGS += ' `${PKG_CONFIG} libelf --cflags` >> $CONFIG
-+	echo 'ELF_LDLIBS += ' `${PKG_CONFIG} libelf --libs` >>$CONFIG
-     else
- 	echo "no"
-     fi
---- a/lib/Makefile
-+++ b/lib/Makefile
-@@ -11,9 +11,17 @@ UTILOBJ = utils.o rt_names.o ll_map.o ll
- 	inet_proto.o namespace.o json_writer.o json_print.o \
- 	names.o color.o bpf.o exec.o fs.o
- 
-+ELFOBJ=$(patsubst %.o,%.elf.o,$(UTILOBJ))
-+
- NLOBJ=libgenl.o libnetlink.o
- 
--all: libnetlink.a libutil.a
-+all: libnetlink.a libutil.a libutil-elf.a
-+
-+%.o: %.c
-+	$(QUIET_CC)$(CC) $(CFLAGS) -UHAVE_ELF $(EXTRA_CFLAGS) -c -o $@ $<
-+
-+%.elf.o: %.c
-+	$(QUIET_CC)$(CC) $(CFLAGS) $(ELF_CFLAGS) $(EXTRA_CFLAGS) -c -o $@ $<
- 
- libnetlink.a: $(NLOBJ)
- 	$(QUIET_AR)$(AR) rcs $@ $^
-@@ -21,7 +29,10 @@ libnetlink.a: $(NLOBJ)
- libutil.a: $(UTILOBJ) $(ADDLIB)
- 	$(QUIET_AR)$(AR) rcs $@ $^
- 
-+libutil-elf.a: $(ELFOBJ) $(ADDLIB)
-+	$(QUIET_AR)$(AR) rcs $@ $^
-+
- install:
- 
- clean:
--	rm -f $(NLOBJ) $(UTILOBJ) $(ADDLIB) libnetlink.a libutil.a
-+	rm -f $(NLOBJ) $(UTILOBJ) $(ELFOBJ) $(ADDLIB) libnetlink.a libutil.a libutil-elf.a
---- a/tc/Makefile
-+++ b/tc/Makefile
-@@ -133,8 +133,8 @@ MODDESTDIR := $(DESTDIR)$(LIBDIR)/tc
- 
- all: tc $(TCSO)
- 
--tc: $(TCOBJ) $(LIBNETLINK) libtc.a
--	$(QUIET_LINK)$(CC) $^ $(LDFLAGS) $(LDLIBS) -o $@
-+tc: $(TCOBJ) $(subst libutil.a,libutil-elf.a,$(LIBNETLINK)) libtc.a
-+	$(QUIET_LINK)$(CC) $^ $(LDFLAGS) $(LDLIBS) $(ELF_LDLIBS) -o $@
- 
- libtc.a: $(TCLIB)
- 	$(QUIET_AR)$(AR) rcs $@ $^