From c7e3acf5d096c4830504916ba65a5c1a52cbae9e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Toke=20H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>
Date: Wed, 29 Sep 2021 01:43:35 +0200
Subject: [PATCH] common.mk: support generating skeletons for BPF object files
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Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
 .gitignore    | 1 +
 configure     | 2 ++
 lib/common.mk | 8 ++++++--
 3 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/.gitignore b/.gitignore
index da4413f..e4b5e9d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -3,3 +3,4 @@ config.mk
 compile_commands.json
 *.ll
 *.o
+*.skel.h
diff --git a/configure b/configure
index 4564156..18d13c8 100755
--- a/configure
+++ b/configure
@@ -17,6 +17,7 @@ check_toolchain()
     : ${CC=gcc}
     : ${CLANG=clang}
     : ${LLC=llc}
+    : ${BPFTOOL=bpftool}
 
     for TOOL in $PKG_CONFIG $CC $CLANG $LLC; do
         if [ ! $(command -v ${TOOL} 2>/dev/null) ]; then
@@ -29,6 +30,7 @@ check_toolchain()
     echo "CC:=${CC}" >>$CONFIG
     echo "CLANG:=${CLANG}" >>$CONFIG
     echo "LLC:=${LLC}" >>$CONFIG
+    echo "BPFTOOL:=${BPFTOOL}" >>$CONFIG
 }
 
 check_elf()
diff --git a/lib/common.mk b/lib/common.mk
index e9c06ed..afe2164 100644
--- a/lib/common.mk
+++ b/lib/common.mk
@@ -12,6 +12,7 @@
 #
 BPF_C = ${BPF_TARGETS:=.c}
 BPF_OBJ = ${BPF_C:.c=.o}
+BPF_SKEL = ${BPF_SKEL_OBJ:.o=.skel.h}
 USER_C := ${USER_TARGETS:=.c}
 USER_OBJ := ${USER_C:.c=.o}
 BPF_OBJ_INSTALL ?= $(BPF_OBJ)
@@ -51,7 +52,7 @@ BPF_CFLAGS += -I$(INCLUDE_DIR) -I$(HEADER_DIR) $(EXTRA_CFLAGS)
 
 BPF_HEADERS := $(wildcard $(HEADER_DIR)/*/*.h) $(wildcard $(INCLUDE_DIR)/*/*.h)
 
-all: $(USER_TARGETS) $(BPF_OBJ) $(EXTRA_TARGETS)
+all: $(USER_TARGETS) $(BPF_OBJ) $(EXTRA_TARGETS) $(BPF_SKEL)
 
 .PHONY: clean
 clean::
@@ -70,7 +71,7 @@ LIB_H := ${LIB_OBJS:.o=.h}
 $(LIB_OBJS): %.o: %.c %.h $(LIB_H)
 	$(Q)$(MAKE) -C $(dir $@) $(notdir $@)
 
-$(USER_TARGETS): %: %.c  $(OBJECT_LIBBPF) $(OBJECT_LIBXDP) $(LIBMK) $(LIB_OBJS) $(KERN_USER_H) $(EXTRA_DEPS) $(EXTRA_USER_DEPS)
+$(USER_TARGETS): %: %.c  $(OBJECT_LIBBPF) $(OBJECT_LIBXDP) $(LIBMK) $(LIB_OBJS) $(KERN_USER_H) $(EXTRA_DEPS) $(EXTRA_USER_DEPS) $(BPF_SKEL)
 	$(QUIET_CC)$(CC) -Wall $(CFLAGS) $(LDFLAGS) -o $@ $(LIB_OBJS) \
 	 $< $(LDLIBS)
 
@@ -86,6 +87,9 @@ $(BPF_OBJ): %.o: %.c $(KERN_USER_H) $(EXTRA_DEPS) $(BPF_HEADERS) $(LIBMK)
 	    -O2 -emit-llvm -c -g -o ${@:.o=.ll} $<
 	$(QUIET_LLC)$(LLC) -march=bpf -filetype=obj -o $@ ${@:.o=.ll}
 
+$(BPF_SKEL): %.skel.h: %.o
+	$(QUIET_GEN)$(BPFTOOL) gen skeleton ${@:.skel.h=.o} > $@
+
 
 .PHONY: test
 ifeq ($(TEST_FILE),)