/usr/src/linux-source-4.4.0/debian/scripts/retpoline-check is in linux-source-4.4.0 4.4.0-139.165.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 | #!/bin/bash
flavour="$1"
prev_abidir="$2"
curr_abidir="$3"
skipretpoline="$4"
echo "II: Checking retpoline indirections for $flavour...";
if [ "$skipretpoline" = 'true' ]; then
	echo "manual request ignoring retpoline delta"
fi
if [ -f "$prev_abidir/ignore.retpoline" -o \
     -f "$prev_abidir/$flavour.ignore.retpoline" ]; then
	echo "explicitly ignoring retpoline delta"
	skipretpoline='true'
fi
prev="$prev_abidir/$flavour.retpoline"
curr="$curr_abidir/$flavour.retpoline"
if [ ! -f "$prev" ]; then
	echo "previous retpoline file missing!"
	echo "   $prev"
	prev="/dev/null"
fi
if [ ! -f "$curr" ]; then
	echo "current retpoline file missing!"
	echo "   $curr"
	curr="/dev/null"
fi
echo "II: retpoline delta in this package..."
rc=0
diff -u "$prev" "$curr" || true
count=$( diff -u "$prev" "$curr" | grep '^+[^+]' | wc -l )
if [ "$count" != 0 ]; then
	rc=1
	echo "WW: $count new retpoline sequences detected"
fi
echo "II: Done";
if [ "$skipretpoline" = 'true' -a "$rc" -ne 0 ]; then
	echo "II: ignoring errors"
	exit 0
fi
exit "$rc"
 |