Move distro hack to tools/vmlinux-distro-hack

debian/patches/dkms-use-debian-hack.patch → debian/patches/dkms-use-distro-hack.patch

@@ -4,7 +4,7 @@
  PACKAGE_NAME="mimic"
  PACKAGE_VERSION="0.4.2"
 -MAKE[0]="make KERNEL_UNAME=$kernelver"
-+MAKE[0]="make KERNEL_UNAME=$kernelver DEBIAN_HACK=1"
++MAKE[0]="make KERNEL_UNAME=$kernelver DISTRO_HACK=1"
  CLEAN="make clean"
  BUILT_MODULE_NAME[0]="mimic"
  DEST_MODULE_LOCATION[0]="/kernel/drivers/misc"

debian/patches/series

@@ -1 +1 @@
-dkms-use-debian-hack.patch
+dkms-use-distro-hack.patch

kmod/Makefile

@@ -1,62 +1,52 @@
 obj-m += mimic.o
+ccflags-y := -D_MIMIC_KMOD
 
 KERNEL_UNAME ?= $(shell uname -r)
-
 SYSTEM_BUILD_DIR := /lib/modules/$(KERNEL_UNAME)/build
-PWD := $(CURDIR)
-
-ccflags-y := -D_MIMIC_KMOD
 
-# Notes on Debian hack:
+# Notes on distro hack:
 #
-# Debian does not ship vmlinux nor resolve_btfids in
-# linux-headers like Arch Linux does, so we need to refer to externally
-# built one in order to build kernel module BTF successfully.
+# - Debian does not ship vmlinux nor resolve_btfids in
+#   linux-headers like Arch Linux does, so we need to refer to externally
+#   built one in order to build kernel module BTF successfully.
 #
-# Ubuntu does not ship vmlinux, but provides resolve_btfid, and there
-# might be dead symlinks (e.g. rust/) inside. This needs to work around as
-# well.
+# - Ubuntu does not ship vmlinux, but provides resolve_btfids, and there
+#   might be dead symlinks (e.g. rust/) inside. This needs to work around as
+#   well.
+#
+# - Fedora does not provide resolve_btfids. However they ship the source code
+#   of it inside /lib/modules/*.
+#
+# Other distributions lacking components necessary to build kernel module BTF
+# can also use the hack in packaging.
+
+ifdef DISTRO_HACK
+
+build_dir := build
+
+VMLINUX_DISTRO_HACK ?= /usr/lib/mimic/vmlinux-distro-hack
+RESOLVE_BTFIDS ?= /usr/lib/mimic/resolve_btfids
+
+export EXTRACT_VMLINUX ?= /usr/lib/mimic/extract-vmlinux
+export EXTRACT_BTF ?= /usr/lib/mimic/extract-btf
+export VMLINUX_SUFFIX ?= -$(KERNEL_UNAME)
 
-ifdef DEBIAN_HACK
-BUILD := build
 else
-BUILD := $(SYSTEM_BUILD_DIR)
+build_dir := $(SYSTEM_BUILD_DIR)
 endif
 
 all:
-ifdef DEBIAN_HACK
-	cp -rL $(SYSTEM_BUILD_DIR) $(BUILD) || true
-
-	if [ ! -f $(BUILD)/vmlinux ]; then \
-		if [ -f /boot/vmlinuz-$(KERNEL_UNAME) ]; then \
-			/usr/lib/mimic/extract-vmlinux /boot/vmlinuz-$(KERNEL_UNAME) > $(BUILD)/vmlinux; \
-			[ $? -eq 0 ] || /usr/lib/mimic/extract-btf /boot/vmlinuz-$(KERNEL_UNAME) > $(BUILD)/vmlinux; \
-			if [ $? -ne 0 ]; then \
-				echo ERROR: cannot extract BTF from boot image; \
-				exit 1; \
-			fi \
-		elif [ -f /boot/vmlinux-$(KERNEL_UNAME) ]; then \
-			if readelf -h /boot/vmlinux-$(KERNEL_UNAME) >/dev/null 2>/dev/null; then \
-				cp /boot/vmlinux-$(KERNEL_UNAME) $(BUILD)/vmlinux; \
-			else \
-				/usr/lib/mimic/extract-btf /boot/vmlinux-$(KERNEL_UNAME) > $(BUILD)/vmlinux; \
-				if [ $? -ne 0 ]; then \
-					echo ERROR: cannot extract BTF from boot image; \
-					exit 1; \
-				fi \
-			fi \
-		else \
-			echo ERROR: no boot image found; \
-			exit 1; \
-		fi \
-	fi
-
-	if [ ! -f $(BUILD)/tools/bpf/resolve_btfids/resolve_btfids ]; then \
-		install -Dm755 /usr/lib/mimic/resolve_btfids $(BUILD)/tools/bpf/resolve_btfids/resolve_btfids; \
+ifdef DISTRO_HACK
+	cp -rL $(SYSTEM_BUILD_DIR) $(build_dir) || true
+	$(VMLINUX_DISTRO_HACK) $(build_dir)
+	if [ ! -f $(build_dir)/tools/bpf/resolve_btfids/resolve_btfids ]; then \
+		install -Dm755 $(RESOLVE_BTFIDS) $(build_dir)/tools/bpf/resolve_btfids/resolve_btfids; \
 	fi
 endif
-	$(MAKE) -C $(BUILD) M=$(PWD) modules
+	$(MAKE) -C $(build_dir) M=$(CURDIR) modules
 
 clean:
-	rm -rf build
-	[ ! -d $(SYSTEM_BUILD_DIR) ] || $(MAKE) -C $(SYSTEM_BUILD_DIR) M=$(PWD) clean
+ifdef DISTRO_HACK
+	rm -rf $(build_dir)
+endif
+	[ ! -d $(SYSTEM_BUILD_DIR) ] || $(MAKE) -C $(SYSTEM_BUILD_DIR) M=$(CURDIR) clean

kmod/dkms.conf

@@ -1,6 +1,6 @@
 PACKAGE_NAME="mimic"
 PACKAGE_VERSION="0.4.2"
-MAKE[0]="make KERNEL_UNAME=$kernelver"
+MAKE[0]="make KERNEL_UNAME=$kernelver DISTRO_HACK=1"
 CLEAN="make clean"
 BUILT_MODULE_NAME[0]="mimic"
 DEST_MODULE_LOCATION[0]="/kernel/drivers/misc"

tools/vmlinux-distro-hack

@@ -0,0 +1,35 @@
+#!/bin/sh
+#
+# Extract vmlinux (either ELF with .BTF section or entirely BTF blob) when
+# distributions do not provide it in its module path.
+#
+# See kmod/Makefile for usage with automatic kernel building tool e.g. DKMS.
+
+module_dir="$1"
+: "${VMLINUX_SUFFIX:=-$(uname -r)}"
+: "${EXTRACT_VMLINUX:="$module_dir/scripts/extract-vmlinux"}"
+: "${EXTRACT_BTF:="out/extract-btf"}"
+
+if [ ! -f "$module_dir/vmlinux" ]; then
+  if [ -f "/boot/vmlinuz$VMLINUX_SUFFIX" ]; then
+    "$EXTRACT_VMLINUX" "/boot/vmlinuz$VMLINUX_SUFFIX" >"$module_dir/vmlinux"
+    [ $? -eq 0 ] || "$EXTRACT_BTF" "/boot/vmlinuz$VMLINUX_SUFFIX" >"$module_dir/vmlinux"
+    if [ $? -ne 0 ]; then
+      >&2 echo "ERROR: cannot extract BTF from '/boot/vmlinuz$VMLINUX_SUFFIX'"
+      exit 1
+    fi
+  elif [ -f "/boot/vmlinux$VMLINUX_SUFFIX" ]; then
+    if readelf -h "/boot/vmlinux$VMLINUX_SUFFIX" >/dev/null 2>/dev/null; then
+      cp "/boot/vmlinux$VMLINUX_SUFFIX" "$module_dir/vmlinux"
+    else
+      "$EXTRACT_BTF" "/boot/vmlinux$VMLINUX_SUFFIX" >"$module_dir/vmlinux"
+      if [ $? -ne 0 ]; then
+        >&2 echo "ERROR: cannot extract BTF from '/boot/vmlinux$VMLINUX_SUFFIX'"
+        exit 1
+      fi
+    fi
+  else
+    >&2 echo "ERROR: no boot image found"
+    exit 1
+  fi
+fi