#!/bin/bash

set -e

export LC_COLLATE=C

usage()

{

	echo "Tool to generate list of symbols that are used to build kernel livepatches"

	echo

	echo "Usage: ${0##*/} kernel_build_dir klp_symbols"

	echo "  kernel_build_dir    Directory where to find the built kernel binaries"

	echo "  klp_symbols         Output file with the list of symbols"

}

if test "$1" == "-h" -o "$1" == "--help" -o $# -ne 2 ; then

	usage >&2

	exit 1

fi

KLP_DATA_VERSION="0.1"

KERNEL_BUILD_DIR="$1"

KLP_SYMBOLS="$2"

VMLINUX="$KERNEL_BUILD_DIR/vmlinux"

MODVER_DIR="$KERNEL_BUILD_DIR/.tmp_versions"

if ! test -f "$VMLINUX" ; then

	echo "Error: Cannot open file: $VMLINUX" >&2

	exit 1

fi

if ! test -d "$MODVER_DIR" ; then

	# kernel >= 5.3 has *.mod in the build tree

	mod_cnt=$(find "$KERNEL_BUILD_DIR" -name '*.mod' | wc -l)

	if [ $mod_cnt -eq 0 ]; then

		echo "Error: Directory does not exist: $MODVER_DIR" >&2

		exit 1

	fi

	MODVER_DIR="$KERNEL_BUILD_DIR"

fi

get_symbols()

{

	nm -f posix "$1" | grep -v '\( [UN] \)\|\(\.L\|__crc_\)' | cut -d\  -f1

}

echo "klp-convert-symbol-data.$KLP_DATA_VERSION" > "$KLP_SYMBOLS"

echo "*vmlinux" >> "$KLP_SYMBOLS"

get_symbols "$VMLINUX" >> "$KLP_SYMBOLS"

find "$MODVER_DIR" -iname '*.mod' | sort | while read KMOD ; do

    if [ "$MODVER_DIR" = "$KERNEL_BUILD_DIR" ]; then

        # kernel >= 5.3, just replace the suffix

        KO_FILE="${KMOD%.mod}.ko"

    else

        # kernel <= 5.2, read .ko path and file from .mod file

        KO_FILE="$(head -n1 $KMOD)"

    fi

    # obtain module name and its object file by processing .ko file name

    NO_SUFFIX="$(basename -s .ko $KO_FILE)"

    KMOD_NAME="$(echo $NO_SUFFIX | sed 's/-/_/g')"

    OBJ_FILE="$(dirname $KO_FILE)/$NO_SUFFIX.o"

    # write module name to Symbols file

    echo "*$KMOD_NAME" >> "$KLP_SYMBOLS"

    # extract symbols from object file and write them to Symbols file

    get_symbols "$OBJ_FILE" >> "$KLP_SYMBOLS"

done

exit 0