From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 1C710145B27; Fri, 23 May 2025 15:04:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748012649; cv=none; b=VD4btFh6F+vAjMFnXR+N6N27xVv3r0de2znhJbTYOkFCpRPSRUuuj+xjxTFUKay/OhqAGG/rADzYFNRyghzabiRYaDPDncET9rjz6J60HGvIhDQiEREaOM3BN1/8P/arA5Z/U3DUZRIFS7ZTJdT/XovywLePA+gRRBCM01ZwToc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748012649; c=relaxed/simple; bh=LgzZzvYlCla4L/rFHSdbF/gMPO8RB3+Aboi8mlRGv9Q=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=iwT0FGXoi/AT8ZJNAQHJWh0SzfzyWUjcgk/4y9JUbtY0xjT3Nmik4jR5AuddEAAI0+GJw5ooFnB674mB4Cov0Dd4wq3ZZgiL7LjDyeGcRM9M8BfOaxymQG2G1Gs/uxTDxgUV5KaNmCvmWBIltCTjqYU4staKZsVFSWUKfNy0GY4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id AFB781758; Fri, 23 May 2025 08:03:51 -0700 (PDT) Received: from [192.168.20.16] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7CD2E3F5A1; Fri, 23 May 2025 08:04:04 -0700 (PDT) Message-ID: Date: Fri, 23 May 2025 10:03:58 -0500 Precedence: bulk X-Mailing-List: linux-kbuild@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] scripts: add zboot support to extract-vmlinux To: Nathan Chancellor Cc: linux-kbuild@vger.kernel.org, masahiroy@kernel.org, nicolas.schier@linux.dev, linux-kernel@vger.kernel.org, Ard Biesheuvel References: <20250522172941.1669424-1-jeremy.linton@arm.com> <20250522231009.GA2020750@ax162> Content-Language: en-US From: Jeremy Linton In-Reply-To: <20250522231009.GA2020750@ax162> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi, Thanks for looking at this. On 5/22/25 6:10 PM, Nathan Chancellor wrote: > Hi Jeremy, > > On Thu, May 22, 2025 at 12:29:41PM -0500, Jeremy Linton wrote: >> Zboot compressed kernel images are used for arm 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 vmlinux 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 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. >> >> Signed-off-by: Jeremy Linton >> Cc: Ard Biesheuvel >> --- >> scripts/extract-vmlinux | 9 +++++---- >> 1 file changed, 5 insertions(+), 4 deletions(-) >> >> diff --git a/scripts/extract-vmlinux b/scripts/extract-vmlinux >> index 8995cd304e6e..edda1abe226c 100755 >> --- a/scripts/extract-vmlinux >> +++ b/scripts/extract-vmlinux >> @@ -12,10 +12,11 @@ >> >> check_vmlinux() >> { >> - # Use readelf to check if it's a valid ELF >> - # TODO: find a better to way to check that it's really vmlinux >> - # and not just an elf >> - readelf -h $1 > /dev/null 2>&1 || return 1 >> + file $1 |grep 'Linux kernel.*boot executable Image' > /dev/null >> + if [ "$?" -ne "0" ]; then > > Could these two lines be simplified to: > > if file $1 | grep 'Linux kernel.*boot executable Image' > /dev/null; then Yes, but it needs, a '!', which applies to the last operator in the pipeline and for clarity should probably drop the redirection, so I think it ends up: if ! file $1 | grep -q 'Linux kernel.*boot executable Image'; then But it mixes the condition checking and the execution, which is common but maybe not the best idea. Although, if I'm going to reroll this, i think the " Image" should be dropped since it can also have zImage and possibly other reports in the future and AFAIK there isn't any reason to exclude them. > >> + # Use readelf to check if it's a valid ELF, if 'file' fails >> + readelf -h $1 > /dev/null 2>&1 || return 1 >> + fi >> >> cat $1 >> exit 0 >> -- >> 2.49.0 >>