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 B3EF02701CE; Wed, 16 Jul 2025 09:42:08 +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=1752658928; cv=none; b=EXKsG7VCYs30OyBQgWT6ki0DOdpgf4KmgT+ya3tG4CMhJ6KUHA7wa5BhJKOOaT9L8OVgkRX7FK38IZ1//z7x3FLyiXnlwsq4UcysA3HUiBqG2slCWGfxvKUVdmIMM3nxQfVfM5LMz3patAdfKLoMhysbiyh2eulWFQBYYbBeOMk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752658928; c=relaxed/simple; bh=sn26vG9Lu7xSLIkMBif0HOVxMMvKjr4ApngzjQSu0Vk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=R54nduzIvV4naAgbrevCOEX+R/gv1VVuN27DO/akd+Y38hTHMn71cD6TfBbAqQpwUEWoEq85ic5Ono/o+tKOhmE7iTtKOuUOzoSkPfbWZcaCp0xE0U6gRPeiXudPkBCg1eT8HwmtHmW23sYCDei8f0r58nTIfPm8X5uClfv91xU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Al71AiLa; 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="Al71AiLa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B65AEC4CEF0; Wed, 16 Jul 2025 09:42:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1752658928; bh=sn26vG9Lu7xSLIkMBif0HOVxMMvKjr4ApngzjQSu0Vk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Al71AiLaI/dpXeER9zPwY30mq0qNyAGHefX0OEvfJFBjNNKE4WmSEyVWgKckjuIVC srJxfiYeO+d6AoPSqqK6HyCsZuIUkokJaMZ1L3/VDbN92IJPTYtZvbQ1X5e5mXJ6Z+ tUP2o9EwGzHBHGUOnow0nKfE+XNRyt5NwOIaF+Bk= Date: Wed, 16 Jul 2025 11:42:05 +0200 From: Greg KH To: Srinivas Kandagatla 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: <2025071656-heap-student-9163@gregkh> References: <20250712181729.6495-1-srini@kernel.org> <20250712181729.6495-2-srini@kernel.org> <2025071308-upfront-romp-fa1e@gregkh> <2025071313-zippy-boneless-da1c@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: On Tue, Jul 15, 2025 at 04:44:00PM +0100, Srinivas Kandagatla wrote: > > > On 7/13/25 4:42 PM, Greg KH wrote: > > 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? > May be not, AFAIU Fixes: d5542923f200 ("nvmem: add driver handling > U-Boot environment variables") should be enough. Great, can you fix this up and resend? thanks, greg k-h