package/libbpf: build for host

Signed-off-by: Francis Laniel <flaniel@linux.microsoft.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/libbpf/libbpf.mk

@@ -10,6 +10,7 @@ LIBBPF_LICENSE = GPL-2.0, LGPL-2.1, BSD-2-Clause
 LIBBPF_LICENSE_FILES = LICENSE LICENSE.BSD-2-Clause LICENSE.LGPL-2.1
 LIBBPF_CPE_ID_VENDOR = libbpf_project
 LIBBPF_DEPENDENCIES = host-bison host-flex host-pkgconf elfutils zlib
+HOST_LIBBPF_DEPENDENCIES = host-bison host-flex host-pkgconf host-elfutils host-zlib
 LIBBPF_INSTALL_STAGING = YES
 
 define LIBBPF_BUILD_CMDS
@@ -38,4 +39,27 @@ define LIBBPF_INSTALL_TARGET_CMDS
 		-C $(@D)/src install DESTDIR=$(TARGET_DIR)
 endef
 
+# We need to install_uapi_headers so we have btf.h to compile
+# host-pahole.
+# Nonetheless, this target adds bpf.h which generates a conflict when
+# building the kernel:
+# In file included from libbpf_internal.h:17:0, from strset.c:9:
+# relo_core.h:10:6: error: nested redefinition of 'enum bpf_core_relo_kind'
+# enum bpf_core_relo_kind {
+# ^~~~~~~~~~~~~~~~~~
+# relo_core.h:10:6: error: redeclaration of 'enum bpf_core_relo_kind'
+# In file included from libbpf_legacy.h:13:0,
+# 		from libbpf_internal.h:16,
+# 		from strset.c:9:
+# /home/francis/buildroot/output/host/include/linux/bpf.h:6497:6: note: originally defined here
+# enum bpf_core_relo_kind {
+# So, better to remove remove it now since we do not need it to build
+# host-pahole, the only user of host-libbpf.
+define HOST_LIBBPF_INSTALL_CMDS
+	$(HOST_MAKE_ENV) $(HOST_CONFIGURE_OPTS) $(MAKE) \
+		-C $(@D)/src install install_uapi_headers DESTDIR=$(HOST_DIR)
+	rm $(HOST_DIR)/include/linux/bpf.h
+endef
+
 $(eval $(generic-package))
+$(eval $(host-generic-package))