From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 600BD27A93A; Sun, 13 Jul 2025 15:42:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752421367; cv=none; b=n05Qm5yejqWFBka4t4kyV+UZJqNqu5qszsnJmbvIaK9Fcx42onK/Brx9/0HR99rcB0ftk4nCn6tzg1SbWTXSmC1YPVOm4iHCPXD5hmMM4MpzQ0263pqFcL1fC9QBu5nhTa6odJYuLvKz63FlR9dN1x6lz/wL/6cfPIo3z/d8DQc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752421367; c=relaxed/simple; bh=9fVhK2Qao63Mjl2DZ29F7+k43ObqsGR4PEs/d+j2wE0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=rMixFpz+L7HozpCYxUEgmPsBXDxq6K5dAlLntNFjMjVHxQVBmqmYPCSN5ybwUfn1+WPpvqdxksF+y0UN6yCFDUYsrJTdjRvg9xNE63iLY0+6OrmrMivFPip+qrAqVvfBdwOcnmztZ2LDO7cjRqPt8fD4bo9ls8B2ouBMfcmkg20= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rdngM802; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rdngM802" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C757C4CEE3; Sun, 13 Jul 2025 15:42:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1752421365; bh=9fVhK2Qao63Mjl2DZ29F7+k43ObqsGR4PEs/d+j2wE0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rdngM802gkniy+dZxOTlJI6Mc25MkfsVUm567ZU00qL/JdKDVxdVPjqqZAM5EAPaT pDW/uW7OL7j9SaAnYL/GSSPupnTzIeszG/SID3TGiaGhkCwCRg7jmdiRk0CNyZWtb3 p4rXSv4XiduNl4nXKgIHNMffqSnfgS/GMZ5MxQBA= Date: Sun, 13 Jul 2025 17:42:43 +0200 From: Greg KH To: srini@kernel.org Cc: linux-kernel@vger.kernel.org, "Michael C. Pratt" , INAGAKI Hiroshi , stable@vger.kernel.org Subject: Re: [PATCH 1/2] nvmem: layouts: u-boot-env: remove crc32 endianness conversion Message-ID: <2025071313-zippy-boneless-da1c@gregkh> References: <20250712181729.6495-1-srini@kernel.org> <20250712181729.6495-2-srini@kernel.org> <2025071308-upfront-romp-fa1e@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2025071308-upfront-romp-fa1e@gregkh> On Sun, Jul 13, 2025 at 05:41:45PM +0200, Greg KH wrote: > On Sat, Jul 12, 2025 at 07:17:26PM +0100, srini@kernel.org wrote: > > From: "Michael C. Pratt" > > > > On 11 Oct 2022, it was reported that the crc32 verification > > of the u-boot environment failed only on big-endian systems > > for the u-boot-env nvmem layout driver with the following error. > > > > Invalid calculated CRC32: 0x88cd6f09 (expected: 0x096fcd88) > > > > This problem has been present since the driver was introduced, > > and before it was made into a layout driver. > > > > The suggested fix at the time was to use further endianness > > conversion macros in order to have both the stored and calculated > > crc32 values to compare always represented in the system's endianness. > > This was not accepted due to sparse warnings > > and some disagreement on how to handle the situation. > > Later on in a newer revision of the patch, it was proposed to use > > cpu_to_le32() for both values to compare instead of le32_to_cpu() > > and store the values as __le32 type to remove compilation errors. > > > > The necessity of this is based on the assumption that the use of crc32() > > requires endianness conversion because the algorithm uses little-endian, > > however, this does not prove to be the case and the issue is unrelated. > > > > Upon inspecting the current kernel code, > > there already is an existing use of le32_to_cpu() in this driver, > > which suggests there already is special handling for big-endian systems, > > however, it is big-endian systems that have the problem. > > > > This, being the only functional difference between architectures > > in the driver combined with the fact that the suggested fix > > was to use the exact same endianness conversion for the values > > brings up the possibility that it was not necessary to begin with, > > as the same endianness conversion for two values expected to be the same > > is expected to be equivalent to no conversion at all. > > > > After inspecting the u-boot environment of devices of both endianness > > and trying to remove the existing endianness conversion, > > the problem is resolved in an equivalent way as the other suggested fixes. > > > > Ultimately, it seems that u-boot is agnostic to endianness > > at least for the purpose of environment variables. > > In other words, u-boot reads and writes the stored crc32 value > > with the same endianness that the crc32 value is calculated with > > in whichever endianness a certain architecture runs on. > > > > Therefore, the u-boot-env driver does not need to convert endianness. > > Remove the usage of endianness macros in the u-boot-env driver, > > and change the type of local variables to maintain the same return type. > > > > If there is a special situation in the case of endianness, > > it would be a corner case and should be handled by a unique "compatible". > > > > Even though it is not necessary to use endianness conversion macros here, > > it may be useful to use them in the future for consistent error printing. > > > > Fixes: d5542923f200 ("nvmem: add driver handling U-Boot environment variables") > > Note, this is a 6.1 commit id, but: > > > Reported-by: INAGAKI Hiroshi > > Link: https://lore.kernel.org/all/20221011024928.1807-1-musashino.open@gmail.com > > Cc: stable@vger.kernel.org # 6.12.x > > Cc: stable@vger.kernel.org # 6.6.x: f4cf4e5: Revert "nvmem: add new config option" > > Cc: stable@vger.kernel.org # 6.6.x: 7f38b70: of: device: Export of_device_make_bus_id() > > Cc: stable@vger.kernel.org # 6.6.x: 4a1a402: nvmem: Move of_nvmem_layout_get_container() in another header > > Cc: stable@vger.kernel.org # 6.6.x: fc29fd8: nvmem: core: Rework layouts to become regular devices > > Cc: stable@vger.kernel.org # 6.6.x: 0331c61: nvmem: core: Expose cells through sysfs > > Cc: stable@vger.kernel.org # 6.6.x: 401df0d: nvmem: layouts: refactor .add_cells() callback arguments > > Cc: stable@vger.kernel.org # 6.6.x: 6d0ca4a: nvmem: layouts: store owner from modules with nvmem_layout_driver_register() > > Cc: stable@vger.kernel.org # 6.6.x: 5f15811: nvmem: layouts: add U-Boot env layout > > Cc: stable@vger.kernel.org # 6.6.x > > That's a load of (short) git ids for just 6.6.y? What about 6.1.y? And really, ALL of those commits are needed for this very tiny patch? Reverting a config option? sysfs apis being added? Huh? confused, greg k-h