kernel-image: build a btf file

Older kernels (e.g., 4.19) do not support /sys/kernel/btf/, so just
generate and add the btf file  into the kernel images.

Signed-off-by: Kornilios Kourtis <[email protected]>

Author: kkourt

dockerfiles/kernel-image

@@ -8,6 +8,9 @@ RUN lvh kernels --dir . fetch     2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . configure 2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . build     2>&1 ${KERNEL_VER}
 
+COPY scripts/generate-btf.sh /tmp/
+RUN /tmp/generate-btf.sh /data/kernels/${KERNEL_VER}/tar-install
+
 FROM busybox
 ARG KERNEL_VER=bpf-next
 COPY --from=builder /data/kernels/${KERNEL_VER}/tar-install /data/kernels/${KERNEL_VER}

dockerfiles/kernel-image-4.19

@@ -8,6 +8,9 @@ RUN lvh kernels --dir . fetch     2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . configure 2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . build     2>&1 ${KERNEL_VER}
 
+COPY scripts/generate-btf.sh /tmp/
+RUN /tmp/generate-btf.sh /data/kernels/${KERNEL_VER}/tar-install
+
 FROM busybox
 ARG KERNEL_VER=4.19
 COPY --from=builder /data/kernels/${KERNEL_VER}/tar-install /data/kernels/${KERNEL_VER}

dockerfiles/kernel-image-5.10

@@ -8,6 +8,9 @@ RUN lvh kernels --dir . fetch     2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . configure 2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . build     2>&1 ${KERNEL_VER}
 
+COPY scripts/generate-btf.sh /tmp/
+RUN /tmp/generate-btf.sh /data/kernels/${KERNEL_VER}/tar-install
+
 FROM busybox
 ARG KERNEL_VER=5.10
 COPY --from=builder /data/kernels/${KERNEL_VER}/tar-install /data/kernels/${KERNEL_VER}

dockerfiles/kernel-image-5.4

@@ -8,6 +8,9 @@ RUN lvh kernels --dir . fetch     2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . configure 2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . build     2>&1 ${KERNEL_VER}
 
+COPY scripts/generate-btf.sh /tmp/
+RUN /tmp/generate-btf.sh /data/kernels/${KERNEL_VER}/tar-install
+
 FROM busybox
 ARG KERNEL_VER=5.4
 COPY --from=builder /data/kernels/${KERNEL_VER}/tar-install /data/kernels/${KERNEL_VER}

dockerfiles/kernel-image-bpf-next

@@ -8,6 +8,9 @@ RUN lvh kernels --dir . fetch     2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . configure 2>&1 ${KERNEL_VER}
 RUN lvh kernels --dir . build     2>&1 ${KERNEL_VER}
 
+COPY scripts/generate-btf.sh /tmp/
+RUN /tmp/generate-btf.sh /data/kernels/${KERNEL_VER}/tar-install
+
 FROM busybox
 ARG KERNEL_VER=bpf-next
 COPY --from=builder /data/kernels/${KERNEL_VER}/tar-install /data/kernels/${KERNEL_VER}

scripts/generate-btf.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+
+set -e
+
+if [ -z $1 ]; then
+	echo "Usage: $0 <kernel_install_dir>"
+	exit 1
+fi
+
+dir="$1"
+bootdir="$dir/boot"
+
+for fname in $bootdir/vmlinux-*; do
+	kernel=$(basename $fname)
+	ver=$(echo $kernel | sed -e 's/vmlinux-//')
+	outfile="$bootdir/kernel-${ver}.btf"
+	rm -f $outfile
+	pahole --btf_encode_detached=$outfile $fname
+	echo "Generated $outfile"
+done