From 8a4c3d2eaafc1870c000071ef682e31853690558 Mon Sep 17 00:00:00 2001
From: Grzegorz Nosek <grzegorz.nosek@sysdig.com>
Date: Wed, 5 Jul 2023 16:24:23 +0200
Subject: [PATCH] cleanup(build): self-contained BPF probe build

The BPF build now no longer touches the source directory
and does not depend on any files outside the (generated)
source directory.

Signed-off-by: Grzegorz Nosek <grzegorz.nosek@sysdig.com>
---
 driver/bpf/CMakeLists.txt            | 46 ++++++++++++++++++++--------
 driver/bpf/{Makefile => Makefile.in} | 11 +------
 driver/bpf/filler_helpers.h          |  2 +-
 driver/bpf/fillers.h                 |  6 ++--
 driver/bpf/probe.c                   |  4 +--
 5 files changed, 41 insertions(+), 28 deletions(-)
 rename driver/bpf/{Makefile => Makefile.in} (86%)

diff --git a/driver/bpf/CMakeLists.txt b/driver/bpf/CMakeLists.txt
index b3e4a06e0b1..3a1128b1c7a 100644
--- a/driver/bpf/CMakeLists.txt
+++ b/driver/bpf/CMakeLists.txt
@@ -9,6 +9,32 @@ configure_file(../driver_config.h.in ${CMAKE_CURRENT_SOURCE_DIR}/../driver_confi
 
 option(BUILD_BPF "Build the BPF driver on Linux" OFF)
 
+# Note: probe.c *must* be the first entry to generate a proper Makefile
+set(BPF_SOURCES
+	probe.c
+	bpf_helpers.h
+	builtins.h
+	filler_helpers.h
+	fillers.h
+	maps.h
+	missing_definitions.h
+	plumbing_helpers.h
+	quirks.h
+	ring_helpers.h
+	types.h
+	${CMAKE_CURRENT_SOURCE_DIR}/../driver_config.h
+	../ppm_api_version.h
+	../ppm_events_public.h
+	../feature_gates.h
+	../ppm_version.h
+	../ppm_fillers.h
+	../ppm_flag_helpers.h
+	../ppm.h
+	../ppm_consumer.h
+	../capture_macro.h
+	../systype_compat.h
+	)
+
 if(BUILD_BPF)
 	# Check minimum kernel version
 	set(bpf_min_kver_map_x86_64 4.14)
@@ -18,25 +44,21 @@ if(BUILD_BPF)
 		message(WARNING "[BPF] To run this driver you need a Linux kernel version >= ${bpf_min_kver_map_${TARGET_ARCH}} but actual kernel version is: ${UNAME_RESULT}")
 	endif()
 
+	foreach(FILENAME IN LISTS BPF_SOURCES)
+		get_filename_component(BASENAME ${FILENAME} NAME)
+		configure_file(${FILENAME} src/${BASENAME} COPYONLY)
+		string(APPEND BPF_DEPENDENCIES "$(src)/${BASENAME} ")
+	endforeach()
+
 	add_custom_target(bpf ALL
 		COMMAND make
 		COMMAND "${CMAKE_COMMAND}" -E copy_if_different probe.o "${CMAKE_CURRENT_BINARY_DIR}"
-		WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
+		WORKING_DIRECTORY "${CMAKE_CURRENT_BINARY_DIR}/src"
 		VERBATIM)
 endif()
 
 install(FILES
-	bpf_helpers.h
-	builtins.h
-	filler_helpers.h
-	fillers.h
+	${BPF_SOURCES}
 	Makefile
-	maps.h
-	plumbing_helpers.h
-	probe.c
-	quirks.h
-	ring_helpers.h
-	missing_definitions.h
-	types.h
 	DESTINATION "src/${DRIVER_PACKAGE_NAME}-${DRIVER_VERSION}/bpf"
 	COMPONENT ${DRIVER_COMPONENT_NAME})
diff --git a/driver/bpf/Makefile b/driver/bpf/Makefile.in
similarity index 86%
rename from driver/bpf/Makefile
rename to driver/bpf/Makefile.in
index 48a3529f253..eae26ff30fc 100644
--- a/driver/bpf/Makefile
+++ b/driver/bpf/Makefile.in
@@ -41,16 +41,7 @@ clean:
 	$(MAKE) -C $(KERNELDIR) M=$$PWD clean
 	@rm -f *~
 
-$(obj)/probe.o: $(src)/probe.c \
-		$(src)/bpf_helpers.h \
-		$(src)/filler_helpers.h \
-		$(src)/fillers.h \
-		$(src)/maps.h \
-		$(src)/plumbing_helpers.h \
-		$(src)/quirks.h \
-		$(src)/ring_helpers.h \
-		$(src)/missing_definitions.h \
-		$(src)/types.h
+$(obj)/probe.o: @BPF_DEPENDENCIES@
 	$(CLANG) $(LINUXINCLUDE) \
 		$(KBUILD_CPPFLAGS) \
 		$(KBUILD_EXTRA_CPPFLAGS) \
diff --git a/driver/bpf/filler_helpers.h b/driver/bpf/filler_helpers.h
index 25e8a0baa83..722fa8414ab 100644
--- a/driver/bpf/filler_helpers.h
+++ b/driver/bpf/filler_helpers.h
@@ -18,7 +18,7 @@ or GPL2.txt for full copies of the license.
 #include <linux/fdtable.h>
 #include <linux/net.h>
 
-#include "../ppm_flag_helpers.h"
+#include "ppm_flag_helpers.h"
 #include "builtins.h"
 
 // Old kernels (like 4.14) have too strict limits on the bpf program length to support 32 path components. For the moment we decrease the limit to 16.
diff --git a/driver/bpf/fillers.h b/driver/bpf/fillers.h
index 2a2bef549fd..26fdbf211f2 100644
--- a/driver/bpf/fillers.h
+++ b/driver/bpf/fillers.h
@@ -9,9 +9,9 @@ or GPL2.txt for full copies of the license.
 #ifndef __FILLERS_H
 #define __FILLERS_H
 
-#include "../systype_compat.h"
-#include "../ppm_flag_helpers.h"
-#include "../ppm_version.h"
+#include "systype_compat.h"
+#include "ppm_flag_helpers.h"
+#include "ppm_version.h"
 #include "bpf_helpers.h"
 #include "missing_definitions.h"
 
diff --git a/driver/bpf/probe.c b/driver/bpf/probe.c
index d885ff18260..c856537a9ac 100644
--- a/driver/bpf/probe.c
+++ b/driver/bpf/probe.c
@@ -15,8 +15,8 @@ or GPL2.txt for full copies of the license.
 #endif
 #include <linux/sched.h>
 
-#include "../driver_config.h"
-#include "../ppm_events_public.h"
+#include "driver_config.h"
+#include "ppm_events_public.h"
 #include "bpf_helpers.h"
 #include "types.h"
 #include "maps.h"