b9f75396ec
Zboot compressed kernel images are used for arm64 kernels on various distros. extract-vmlinux fails with those kernels because the wrapped image is another PE. While this could be a bit confusing, the tools primary purpose of unwrapping and decompressing the contained kernel image makes it the obvious place for this functionality. Add a 'file' check in check_vmlinux() that detects a contained PE image before trying readelf. Recent (FILES_39, Jun/2020) file implementations output something like: "Linux kernel ARM64 boot executable Image, little-endian, 4K pages" Which is also a stronger statement than readelf provides so drop that part of the comment. At the same time this means that kernel images which don't appear to contain a compressed image will be returned rather than reporting an error. Which matches the behavior for existing ELF files. The extracted PE image can then be inspected, or used as would any other kernel PE. Signed-off-by: Jeremy Linton <jeremy.linton@arm.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
1.6 KiB
Executable File
#!/bin/sh
SPDX-License-Identifier: GPL-2.0-only
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extract-vmlinux - Extract uncompressed vmlinux from a kernel image
Inspired from extract-ikconfig
(c) 2009,2010 Dick Streefland dick@streefland.net
(c) 2011 Corentin Chary corentin.chary@gmail.com
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check_vmlinux() { if file "$1" | grep -q 'Linux kernel.*boot executable' || readelf -h "$1" > /dev/null 2>&1 then cat "$1" exit 0 fi }
try_decompress() { # The obscure use of the "tr" filter is to work around older versions of # "grep" that report the byte offset of the line instead of the pattern.
# Try to find the header ($1) and decompress from here
for pos in `tr "$1\n$2" "\n$2=" < "$img" | grep -abo "^$2"`
do
pos=${pos%%:*}
tail -c+$pos "$img" | $3 > $tmp 2> /dev/null
check_vmlinux $tmp
done
}
Check invocation:
me=${0##*/} img=$1 if [ $# -ne 1 -o ! -s "$img" ] then echo "Usage: $me " >&2 exit 2 fi
Prepare temp files:
tmp=$(mktemp /tmp/vmlinux-XXX) trap "rm -f $tmp" 0
That didn't work, so retry after decompression.
try_decompress '\037\213\010' xy gunzip try_decompress '\3757zXZ\000' abcde unxz try_decompress 'BZh' xy bunzip2 try_decompress '\135\0\0\0' xxx unlzma try_decompress '\211\114\132' xy 'lzop -d' try_decompress '\002!L\030' xxx 'lz4 -d' try_decompress '(\265/\375' xxx unzstd
Finally check for uncompressed images or objects:
check_vmlinux $img
Bail out:
echo "$me: Cannot find vmlinux." >&2