From 35dac71cff8f68f065a6719631db919d0640d5e5 Mon Sep 17 00:00:00 2001 From: "Guilherme G. Piccoli" Date: Mon, 20 Jan 2025 16:04:26 -0300 Subject: scripts: add script to extract built-in firmware blobs There is currently no tool to extract a firmware blob that is built-in on vmlinux to the best of my knowledge. So if we have a kernel image containing the blobs, and we want to rebuild the kernel with some debug patches for example (and given that the image also has IKCONFIG=y), we currently can't do that for the same versions for all the firmware blobs, _unless_ we have exact commits of linux-firmware for the specific versions for each firmware included. Through the options CONFIG_EXTRA_FIRMWARE{_DIR} one is able to build a kernel including firmware blobs in a built-in fashion. This is usually the case of built-in drivers that require some blobs in order to work properly, for example, like in non-initrd based systems. Add hereby a script to extract these blobs from a non-stripped vmlinux, similar to the idea of "extract-ikconfig". The firmware loader interface saves such built-in blobs as rodata entries, having a field for the FW name as "_fw___bin"; the tool extracts files named "_" for each rodata firmware entry detected. It makes use of awk, bash, dd and readelf, pretty standard tooling for Linux development. With this tool, we can blindly extract the FWs and easily re-add them in the new debug kernel build, allowing a more deterministic testing without the burden of "hunting down" the proper version of each firmware binary. Link: https://lkml.kernel.org/r/20250120190436.127578-1-gpiccoli@igalia.com Signed-off-by: Guilherme G. Piccoli Suggested-by: Thadeu Lima de Souza Cascardo Reviewed-by: Thadeu Lima de Souza Cascardo Cc: Danilo Krummrich Cc: Greg Kroah-Hartman Cc: Luis Chamberalin Cc: Masahiro Yamada Cc: Nathan Chancellor Cc: Nicolas Schier Cc: "Rafael J. Wysocki" Cc: Russ Weight Signed-off-by: Andrew Morton --- scripts/extract-fwblobs | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100755 scripts/extract-fwblobs (limited to 'scripts/extract-fwblobs') diff --git a/scripts/extract-fwblobs b/scripts/extract-fwblobs new file mode 100755 index 000000000000..53729124e5a0 --- /dev/null +++ b/scripts/extract-fwblobs @@ -0,0 +1,30 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# ----------------------------------------------------------------------------- +# Extracts the vmlinux built-in firmware blobs - requires a non-stripped image +# ----------------------------------------------------------------------------- + +if [ -z "$1" ]; then + echo "Must provide a non-stripped vmlinux as argument" + exit 1 +fi + +read -r RD_ADDR_HEX RD_OFF_HEX <<< "$( readelf -SW "$1" |\ +grep -w rodata | awk '{print "0x"$5" 0x"$6}' )" + +FW_SYMS="$(readelf -sW "$1" |\ +awk -n '/fw_end/ { end=$2 ; print name " 0x" start " 0x" end; } { start=$2; name=$8; }')" + +while IFS= read -r entry; do + read -r FW_NAME FW_ADDR_ST_HEX FW_ADDR_END_HEX <<< "$entry" + + # Notice kernel prepends _fw_ and appends _bin to the FW name + # in rodata; hence we hereby filter that out. + FW_NAME=${FW_NAME:4:-4} + + FW_OFFSET="$(printf "%d" $((FW_ADDR_ST_HEX - RD_ADDR_HEX + RD_OFF_HEX)))" + FW_SIZE="$(printf "%d" $((FW_ADDR_END_HEX - FW_ADDR_ST_HEX)))" + + dd if="$1" of="./${FW_NAME}" bs="${FW_SIZE}" count=1 iflag=skip_bytes skip="${FW_OFFSET}" +done <<< "${FW_SYMS}" -- cgit v1.2.3