bpftool: add host build

Besides probing BPF information in running system, bpftool is also used in
generating skeleton, dumping BTF, etc. that is widely used in modern BPF
development. Make it available as a host tool so that we can use it in
package build.

Tested build targeting malta/le on Arch Linux x86_64. bpftools currently
does not support processing cross-endian BPF objects, so big-endian host
is needed to build for big-endian targets using bpftools.

Signed-off-by: Eric Long <i@hack3r.moe>
Link: https://github.com/openwrt/openwrt/pull/16122
Signed-off-by: Robert Marko <robimarko@gmail.com>

diff --git a/package/network/utils/bpftool/Makefile b/package/network/utils/bpftool/Makefile
index 45f8904d8ddf74def5d10d0041b2ba792ded0e47..f2726d189690901aa07fb7bef3fff97dc45338a7 100644 (file)
--- a/package/network/utils/bpftool/Makefile
+++ b/package/network/utils/bpftool/Makefile
@@ -22,8 +22,11 @@ PKG_BUILD_FLAGS:=no-mips16 gc-sections lto
 PKG_BUILD_PARALLEL:=1
 PKG_INSTALL:=1
 
+HOST_BUILD_PARALLEL:=1
+
 include $(INCLUDE_DIR)/package.mk
 include $(INCLUDE_DIR)/nls.mk
+include $(INCLUDE_DIR)/host-build.mk
 
 define Package/bpftool/Default
   SECTION:=net
@@ -88,5 +91,30 @@ define Package/bpftool-$(BUILD_VARIANT)/install
                $(1)/usr/libexec/bpftool-$(BUILD_VARIANT)
 endef
 
+HOST_MAKE_FLAGS += \
+       OUTPUT="$(HOST_BUILD_DIR)/" \
+       prefix="/usr" \
+       $(if $(findstring c,$(OPENWRT_VERBOSE)),V=1,V='') \
+       check_feat=0 \
+       feature-clang-bpf-co-re=0 \
+       feature-libbfd=1 \
+       feature-llvm=0 \
+       feature-libcap=0 \
+       feature-disassembler-four-args=1 \
+       feature-disassembler-init-styled=1
+
+HOST_MAKE_PATH = src
+
+define Host/Install
+       $(INSTALL_DIR) $(STAGING_DIR_HOST)/usr/sbin
+       $(INSTALL_BIN) $(HOST_BUILD_DIR)/bpftool \
+               $(STAGING_DIR_HOST)/usr/sbin/bpftool
+endef
+
+define Host/Clean
+       rm -f $(STAGING_DIR_HOST)/usr/sbin/bpftool
+endef
+
 $(eval $(call BuildPackage,bpftool-full))
 $(eval $(call BuildPackage,bpftool-minimal))
+$(eval $(call HostBuild))