btfdiff

#!/bin/bash
# SPDX-License-Identifier: GPL-2.0-only
# Copyright © 2019 Red Hat Inc, Arnaldo Carvalho de Melo <acme@redhat.com>
# Use pahole to produce output from BTF and from DWARF, then do a diff
# Use --flat_arrays with DWARF as BTF, like CTF, flattens arrays.
# Use --show_private_classes as BTF shows all structs, while pahole knows
# if some struct is defined only inside another struct/class or in a function,
# this information is not available when loading from BTF.

if [ $# -eq 0 ] ; then
	echo "Usage: btfdiff <filename_with_DWARF_and_maybe_BTF_info> [<filename_with_BTF_info>]"
	exit 1
fi

dwarf_input=$1
btf_input=$dwarf_input

if [ $# -eq 2 ] ; then
	btf_input=$2
fi

btf_output=$(mktemp /tmp/btfdiff.btf.XXXXXX)
dwarf_output=$(mktemp /tmp/btfdiff.dwarf.XXXXXX)
pahole_bin=${PAHOLE-"pahole"}

${pahole_bin} -E -F dwarf \
	      --flat_arrays \
	      --sort \
	      --jobs \
	      --suppress_aligned_attribute \
	      --suppress_force_paddings \
	      --suppress_packed \
	      --lang_exclude rust \
	      --show_private_classes $dwarf_input > $dwarf_output &
dwarf=$!

${pahole_bin} -E -F btf \
	      --sort \
	      --suppress_aligned_attribute \
	      --suppress_packed \
	      $btf_input > $btf_output

wait $dwarf

diff -up $dwarf_output $btf_output

rm -f $btf_output $dwarf_output
exit 0