[PATCH] extract-vmlinux: Check for uncompressed image as fallback

From: Helge Deller
Date: Tue Oct 16 2018 - 02:03:47 EST

As on x86-64 and other architectures, the boot kernel on parisc (vmlinuz
and bzImage) contains a full compressed copy of the final kernel
executable (vmlinux.bin.gz), which one should be able to extract with
the extract-vmlinux script.

But on parisc extracting the kernel with extract-vmlinux fails.
Currently the script first checks if the given file is an ELF file
(which is true on parisc) and if so returns it. Thus on parisc we
unexpectedly get back the vmlinuz boot file instead of the uncompressed
vmlinux image.

This patch fixes this issue by reverting the logic. It now first tries
to find a compression signature in the given file and if that fails it
checks the file itself as fallback.

Signed-off-by: Helge Deller <deller@xxxxxx>

diff --git a/scripts/extract-vmlinux b/scripts/extract-vmlinux
index e6239f39abad..85e1f32fb4a0 100755
--- a/scripts/extract-vmlinux
+++ b/scripts/extract-vmlinux
@@ -48,9 +48,6 @@ fi
tmp=$(mktemp /tmp/vmlinux-XXX)
trap "rm -f $tmp" 0

-# Initial attempt for uncompressed images or objects:
-check_vmlinux $img
# That didn't work, so retry after decompression.
try_decompress '\037\213\010' xy gunzip
try_decompress '\3757zXZ\000' abcde unxz
@@ -60,5 +57,8 @@ 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