path: root/scripts/livepatch/klp-build

#!/bin/bash
# SPDX-License-Identifier: GPL-2.0
#
# Build a livepatch module

# shellcheck disable=SC1090,SC2155,SC2164

if (( BASH_VERSINFO[0]  < 4 || \
     (BASH_VERSINFO[0] == 4 && BASH_VERSINFO[1] < 4) )); then
		echo "error: this script requires bash 4.4+" >&2
	exit 1
fi

set -o errtrace
set -o pipefail
set -o nounset

# Allow doing 'cmd | mapfile -t array' instead of 'mapfile -t array < <(cmd)'.
# This helps keep execution in pipes so pipefail+ERR trap can catch errors.
shopt -s lastpipe

unset DEBUG_CLONE DIFF_CHECKSUM SKIP_CLEANUP VERBOSE XTRACE

REPLACE=1
SHORT_CIRCUIT=0
JOBS="$(getconf _NPROCESSORS_ONLN)"
shopt -o xtrace | grep -q 'on' && XTRACE=1

# Avoid removing the previous $TMP_DIR until args have been fully processed.
KEEP_TMP=1

SCRIPT="$(basename "$0")"
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
FIX_PATCH_LINES="$SCRIPT_DIR/fix-patch-lines"

OBJTOOL="$PWD/tools/objtool/objtool"
CONFIG="$PWD/.config"
TMP_DIR="$PWD/klp-tmp"

ORIG_DIR="$TMP_DIR/1-orig"
PATCHED_DIR="$TMP_DIR/2-patched"
ORIG_CSUM_DIR="$TMP_DIR/3-checksum-orig"
PATCHED_CSUM_DIR="$TMP_DIR/3-checksum-patched"
DIFF_DIR="$TMP_DIR/4-diff"
KMOD_DIR="$TMP_DIR/5-kmod"

STASH_DIR="$TMP_DIR/stash"
TIMESTAMP="$TMP_DIR/timestamp"
PATCH_TMP_DIR="$TMP_DIR/tmp"

KLP_DIFF_LOG="$DIFF_DIR/diff.log"

# Terminal output colors
read -r COLOR_RESET COLOR_BOLD COLOR_ERROR COLOR_WARN <<< ""
if [[ -t 1 && -t 2 ]]; then
	COLOR_RESET="\033[0m"
	COLOR_BOLD="\033[1m"
	COLOR_ERROR="\033[0;31m"
	COLOR_WARN="\033[0;33m"
fi

grep0() {
	# shellcheck disable=SC2317
	command grep "$@" || true
}

# Because pipefail is enabled, the grep0 helper should be used instead of
# grep, otherwise a failed match can propagate to an error.
grep() {
	echo "error: $SCRIPT: use grep0 or 'command grep' instead of bare grep" >&2
	exit 1
}

status() {
	echo -e "${COLOR_BOLD}$*${COLOR_RESET}"
}

warn() {
	echo -e "${COLOR_WARN}warning${COLOR_RESET}: $SCRIPT: $*" >&2
}

die() {
	echo -e "${COLOR_ERROR}error${COLOR_RESET}: $SCRIPT: $*" >&2
	exit 1
}

declare -a STASHED_FILES

stash_file() {
	local file="$1"
	local rel_file="${file#"$PWD"/}"

	[[ ! -e "$file" ]] && die "no file to stash: $file"

	mkdir -p "$STASH_DIR/$(dirname "$rel_file")"
	cp -f "$file" "$STASH_DIR/$rel_file"

	STASHED_FILES+=("$rel_file")
}

restore_files() {
	local file

	for file in "${STASHED_FILES[@]}"; do
		mv -f "$STASH_DIR/$file" "$PWD/$file" || warn "can't restore file: $file"
	done

	STASHED_FILES=()
}

cleanup() {
	set +o nounset
	revert_patches
	restore_files
	[[ "$KEEP_TMP" -eq 0 ]] && rm -rf "$TMP_DIR"
	return 0
}

trap_err() {
	die "line ${BASH_LINENO[0]}: '$BASH_COMMAND'"
}

trap cleanup  EXIT INT TERM HUP
trap trap_err ERR

__usage() {
	cat <<EOF
Usage: $SCRIPT [OPTIONS] PATCH_FILE(s)
Generate a livepatch module.

Options:
   -f, --show-first-changed	Show address of first changed instruction
   -j, --jobs=<jobs>		Build jobs to run simultaneously [default: $JOBS]
   -o, --output=<file.ko>	Output file [default: livepatch-<patch-name>.ko]
       --no-replace		Disable livepatch atomic replace
   -v, --verbose		Pass V=1 to kernel/module builds

Advanced Options:
   -d, --debug			Show symbol/reloc cloning decisions
   -S, --short-circuit=STEP	Start at build step (requires prior --keep-tmp)
				   1|orig		Build original kernel (default)
				   2|patched		Build patched kernel
				   3|checksum		Generate checksums
				   4|diff		Diff objects
				   5|kmod		Build patch module
   -T, --keep-tmp		Preserve tmp dir on exit

EOF
}

usage() {
	__usage >&2
}

process_args() {
	local keep_tmp=0
	local short
	local long
	local args
	local patch

	short="hfj:o:vdS:T"
	long="help,show-first-changed,jobs:,output:,no-replace,verbose,debug,short-circuit:,keep-tmp"

	args=$(getopt --options "$short" --longoptions "$long" -- "$@") || {
		echo; usage; exit
	}
	eval set -- "$args"

	while true; do
		case "$1" in
			-h | --help)
				usage
				exit 0
				;;
			-f | --show-first-changed)
				DIFF_CHECKSUM=1
				shift
				;;
			-j | --jobs)
				JOBS="$2"
				shift 2
				;;
			-o | --output)
				[[ "$2" != *.ko ]] && die "output filename should end with .ko"
				OUTFILE="$2"
				NAME="$(basename "$OUTFILE")"
				NAME="${NAME%.ko}"
				NAME="$(module_name_string "$NAME")"
				shift 2
				;;
			--no-replace)
				REPLACE=0
				shift
				;;
			-v | --verbose)
				VERBOSE=1
				shift
				;;
			-d | --debug)
				DEBUG_CLONE=1
				keep_tmp=1
				shift
				;;
			-S | --short-circuit)
				[[ ! -d "$TMP_DIR" ]] && die "--short-circuit requires preserved klp-tm