Makefile improvements

[rafaeldtinoco]

What do you think about having static compilation for the Makefile, like the example bellow, so selftests can simply checkout a specific libbpf tag/id and do the tests ? IDEA: instead of having the "run.sh", you could simply change the submodule ID and do a "make".

Wouldn't that be better ?

I can add support for dynamic linking (OS libbpf) so it can be packaged for distros, dynamically linked to libbpf.so, but I thought having it statically compiled included was better for the selftests, as you can control the versions from your submodule tree (to get regressions and similar).

Note: I had issues with the LSM and kernel 5.8 so I wonder if there is a base kernel version for the lib to be based to for the tests.

Please ignore the full paths =o)

diff --git a/Makefile b/Makefile
index d6c26b5..f9de37a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,29 +1,66 @@
-TARGET_BPF := test/test.bpf.o
-VMLINUX_H = test/vmlinux.h
+CC = gcc
+CLANG = clang
+MAKEFLAGS = --jobs=$(shell nproc)
+ARCH = $(shell uname -m | sed 's/x86_64/x86/')
+BPFTOOL = $(shell which bpftool)
 
-GO_SRC := $(shell find . -type f -name '*.go')
-BPF_SRC := $(shell find . -type f -name '*.bpf.c')
-PWD := $(shell pwd)
+OUTPUT = ./output
 
-LIBBPF_HEADERS := /usr/include/bpf
-LIBBPF := "-lbpf"
+# bpf files
 
-.PHONY: all
-all: test
+CFLAGS := -g -O2 -Wall -fpie
+LDFLAGS :=
+BPF_SRC = $(shell find . -type f -name '*.bpf.c')
+BPF_OBJ = $(shell find . -type f -name '*.bpf.c' | sed 's:bpf\.c:bpf\.o:g')
+
+# golang
+
+CGO_CFLAGS = -I$(abspath $(OUTPUT))
+CGO_LDFLAGS = $(LIBBPF_OBJ)
+
+GO_SRC = $(shell find . -type f -name '*.go')
+
+# common
+
+VMLINUX_H := $(abspath $(OUTPUT)/vmlinux.h)
+
+LIBBPF_SRC := $(abspath ./selftest/libbpf-module/src)
+LIBBPF_OBJ := $(abspath ./$(OUTPUT)/libbpf.a)
+LIBBPF_OBJDIR := $(abspath ./$(OUTPUT)/libbpf)
+LIBBPF_DESTDIR := $(abspath ./$(OUTPUT))
+
+# libbpfgo
+
+LIBBPFGO = libbpfgo.go libbpf_cb.go
+
+all: LIBBPFGO
+
+LIBBPFGO: $(BPF_OBJ)
+   CC=$(CLANG) CGO_CFLAGS=$(CGO_CFLAGS) CGO_LDFLAGS=$(CGO_LDFLAGS) \
+       go test -a -x .
+
+$(BPF_OBJ): $(LIBBPF_OBJ) $(VMLINUX_H) | $(OUTPUT)
+   $(CLANG) $(CFLAGS) -target bpf -I $(OUTPUT) -c $(subst bpf.o,bpf.c,$@) -o $@
 
 $(VMLINUX_H):
-   bpftool btf dump file /sys/kernel/btf/vmlinux format c > test/vmlinux.h
+   $(BPFTOOL) btf dump file /sys/kernel/btf/vmlinux format c > $(VMLINUX_H)
+
+$(LIBBPF_OBJ): $(wildcard $(LIBBPF_SRC)/*.[ch]) | $(OUTPUT)/libbpf
+   CC="$(CC)" CFLAGS="$(CFLAGS)" LD_FLAGS="$(LDFLAGS)" \
+      $(MAKE) -C $(LIBBPF_SRC) \
+       BUILD_STATIC_ONLY=1 \
+       OBJDIR=$(LIBBPF_OBJDIR) \
+       DESTDIR=$(LIBBPF_DESTDIR) \
+       INCLUDEDIR= LIBDIR= UAPIDIR= install
 
-go_env := CC=gcc CGO_CFLAGS="-I $(LIBBPF_HEADERS)" CGO_LDFLAGS="$(LIBBPF)"
-.PHONY: test
-test: $(TARGET_BPF) $(GO_SRC)
-   $(go_env) go test -ldflags '-extldflags "-static"' .
+$(OUTPUT) $(OUTPUT)/libbpf:
+   mkdir -p $@
 
-$(TARGET_BPF): $(BPF_SRC) $(VMLINUX_H)
-   clang \
-       -g -O2 -c -target bpf \
-       -o $@ $<
+clean: clean-output clean-bpf clean-vmlinuxh
 
-.PHONY: clean
-clean: 
-   rm $(TARGET_BPF) $(VMLINUX_H)
+clean-output:
+   rm -rf $(OUTPUT)
+clean-bpf:
+   rm -rf $(BPF_OBJ)
+clean-vmlinuxh:
+   rm -rf $(VMLINUX_H)
diff --git a/libbpfgo.go b/libbpfgo.go
index 918b19c..cc58cc4 100644
--- a/libbpfgo.go
+++ b/libbpfgo.go
@@ -1,7 +1,8 @@
 package libbpfgo
 
 /*
-#cgo LDFLAGS: -lelf -lz
+#cgo LDFLAGS: -lelf -lz ${SRCDIR}/output/libbpf.a
+#cgo CFLAGS: -I${SRCDIR}/output/
 
 #include <bpf/bpf.h>
 #include <bpf/libbpf.h>
diff --git a/libbpfgo_test.go b/libbpfgo_test.go
index 08d92ba..87b2275 100644
--- a/libbpfgo_test.go
+++ b/libbpfgo_test.go
@@ -1,18 +1,17 @@
 package libbpfgo
 
 import (
-   "fmt"
    "testing"
 )
 
 func Test_LoadAndAttach(t *testing.T) {
    // load non exisiting file, should fail
-   module, err := NewModuleFromFile("test/foo.bpf.o")
+   module, err := NewModuleFromFile("/home/rafaeldtinoco/work/sources/upstream/libbpfgo/test/foo.bpf.o")
    if err == nil {
        t.Errorf("NewModuleFromFile returned nil error on non-existing file")
    }
 
-   module, err = NewModuleFromFile("test/test.bpf.o")
+   module, err = NewModuleFromFile("/home/rafaeldtinoco/work/sources/upstream/libbpfgo/test/test.bpf.o")
    if err != nil {
        t.Fatalf("NewModuleFromFile failed: %v", err)
    }
@@ -76,16 +75,6 @@ func Test_LoadAndAttach(t *testing.T) {
                return prog.AttachKretprobeLegacy(name)
            },
        },
-       {
-           prog: "socket_connect",
-           attachFn: func(prog *BPFProg, name string) (*BPFLink, error) {
-               if name != "" {
-                   // to make the check for attaching with "foo" happy
-                   return nil, fmt.Errorf("name not empty")
-               }
-               return prog.AttachLSM()
-           },
-       },
    }
 
    for i, test := range attachTests {
diff --git a/test/test.bpf.c b/test/test.bpf.c
index 1d5e1b2..061d6e6 100644
--- a/test/test.bpf.c
+++ b/test/test.bpf.c
@@ -24,8 +24,3 @@ SEC("kretprobe/get_task_pid")
 int kretprobe__get_task_pid(struct pt_regs *ctx) {
    return 0;
 }
-
-SEC("lsm/socket_connect")
-int BPF_PROG(socket_connect, struct socket *sock, struct sockaddr *address, int addrlen) {
-   return 0;
-}

$ sudo make
CC=clang CGO_CFLAGS=-I/home/rafaeldtinoco/work/sources/upstream/libbpfgo/output CGO_LDFLAGS=/home/rafaeldtinoco/work/sources/upstream/libbpfgo/output/libbpf.a \
	go test -a .
ok  	github.com/aquasecurity/libbpfgo	(cached)
[rafaeldtinoco@fujitsu:~/.../libbpfgo][main !?]$