path: root/scripts/
diff options
authorAndrii Nakryiko <>2019-04-02 09:49:50 -0700
committerDaniel Borkmann <>2019-04-03 00:53:07 +0200
commite83b9f55448afce3fe1abcd1d10db9584f8042a6 (patch)
tree4a8ccfba6f274d3b7d4e61c0d11789d9bc0706bb /scripts/
parent99182beed858a1bde22f60046602b9b223225f73 (diff)
kbuild: add ability to generate BTF type info for vmlinux
This patch adds new config option to trigger generation of BTF type information from DWARF debuginfo for vmlinux and kernel modules through pahole, which in turn relies on libbpf for btf_dedup() algorithm. The intent is to record compact type information of all types used inside kernel, including all the structs/unions/typedefs/etc. This enables BPF's compile-once-run-everywhere ([0]) approach, in which tracing programs that are inspecting kernel's internal data (e.g., struct task_struct) can be compiled on a system running some kernel version, but would be possible to run on other kernel versions (and configurations) without recompilation, even if the layout of structs changed and/or some of the fields were added, removed, or renamed. This is only possible if BPF loader can get kernel type info to adjust all the offsets correctly. This patch is a first time in this direction, making sure that BTF type info is part of Linux kernel image in non-loadable ELF section. BTF deduplication ([1]) algorithm typically provides 100x savings compared to DWARF data, so resulting .BTF section is not big as is typically about 2MB in size. [0] [1] Cc: Masahiro Yamada <> Cc: Arnaldo Carvalho de Melo <> Cc: Daniel Borkmann <> Cc: Alexei Starovoitov <> Cc: Yonghong Song <> Cc: Martin KaFai Lau <> Signed-off-by: Andrii Nakryiko <> Acked-by: David S. Miller <> Acked-by: Alexei Starovoitov <> Acked-by: Daniel Borkmann <> Signed-off-by: Daniel Borkmann <>
Diffstat (limited to 'scripts/')
1 files changed, 19 insertions, 1 deletions
diff --git a/scripts/ b/scripts/
index dc0e8c5a1402..dd2b31ccca6a 100755
--- a/scripts/
+++ b/scripts/
@@ -35,7 +35,7 @@ set -e
if [ "${quiet}" != "silent_" ]; then
- printf " %-7s %s\n" ${1} ${2}
+ printf " %-7s %s\n" "${1}" "${2}"
@@ -91,6 +91,20 @@ vmlinux_link()
+# generate .BTF typeinfo from DWARF debuginfo
+ local pahole_ver;
+ pahole_ver=$(${PAHOLE} --version | sed -E 's/v([0-9]+)\.([0-9]+)/\1\2/')
+ if [ "${pahole_ver}" -lt "113" ]; then
+ info "BTF" "${1}: pahole version $(${PAHOLE} --version) is too old, need at least v1.13"
+ exit 0
+ fi
+ info "BTF" ${1}
# Create ${2} .o file with all symbols from the ${1} object file
@@ -248,6 +262,10 @@ fi
info LD vmlinux
vmlinux_link "${kallsymso}" vmlinux
+if [ -n "${CONFIG_DEBUG_INFO_BTF}" ]; then
+ gen_btf vmlinux
info SORTEX vmlinux
sortextable vmlinux