From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Tue, 5 May 2020 20:18:18 +0200 Subject: [PATCH V2] mkimage: fit: Do not tail-pad fitImage with external data In-Reply-To: <20200505180648.GZ12564@bill-the-cat> References: <20200501154026.79169-1-marex@denx.de> <20200504112749.GE12564@bill-the-cat> <20200505175022.GW12564@bill-the-cat> <20200505175554.GX12564@bill-the-cat> <2fafc257-b22c-9eda-2cd3-53eefcd09a0d@denx.de> <20200505180648.GZ12564@bill-the-cat> Message-ID: <8491a801-bfbf-c2e6-0357-78608aa69102@denx.de> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de On 5/5/20 8:06 PM, Tom Rini wrote: > On Tue, May 05, 2020 at 07:59:24PM +0200, Marek Vasut wrote: >> On 5/5/20 7:55 PM, Tom Rini wrote: >>> On Tue, May 05, 2020 at 07:53:42PM +0200, Marek Vasut wrote: >>>> On 5/5/20 7:50 PM, Tom Rini wrote: >>>>> On Tue, May 05, 2020 at 06:39:58PM +0200, Marek Vasut wrote: >>>>>> On 5/5/20 6:37 PM, Alex Kiernan wrote: >>>>>>> On Tue, May 5, 2020 at 2:28 PM Marek Vasut wrote: >>>>>>>> >>>>>>>> On 5/5/20 3:22 PM, Alex Kiernan wrote: >>>>>>>>> On Mon, May 4, 2020 at 12:28 PM Tom Rini wrote: >>>>>>>>>> >>>>>>>>>> On Fri, May 01, 2020 at 05:40:25PM +0200, Marek Vasut wrote: >>>>>>>>>> >>>>>>>>>>> There is no reason to tail-pad fitImage with external data to 4-bytes, >>>>>>>>>>> while fitImage without external data does not have any such padding and >>>>>>>>>>> is often unaligned. DT spec also does not mandate any such padding. >>>>>>>>>>> >>>>>>>>>>> Moreover, the tail-pad fills the last few bytes with uninitialized data, >>>>>>>>>>> which could lead to a potential information leak. >>>>>>>>>>> >>>>>>>>>>> $ echo -n xy > /tmp/data ; \ >>>>>>>>>>> ./tools/mkimage -E -f auto -d /tmp/data /tmp/fitImage ; \ >>>>>>>>>>> hexdump -vC /tmp/fitImage | tail -n 3 >>>>>>>>>>> >>>>>>>>>>> before: >>>>>>>>>>> 00000260 61 2d 6f 66 66 73 65 74 00 64 61 74 61 2d 73 69 |a-offset.data-si| >>>>>>>>>>> 00000270 7a 65 00 00 78 79 64 64 |ze..xydd| >>>>>>>>>>> ^^ ^^ ^^ >>>>>>>>>>> after: >>>>>>>>>>> 00000260 61 2d 6f 66 66 73 65 74 00 64 61 74 61 2d 73 69 |a-offset.data-si| >>>>>>>>>>> 00000270 7a 65 00 78 79 |ze.xy| >>>>>>>>>>> >>>>>>>>>>> Signed-off-by: Marek Vasut >>>>>>>>>>> Reviewed-by: Simon Glass >>>>>>>>>>> Cc: Heinrich Schuchardt >>>>>>>>>>> Cc: Tom Rini >>>>>>>>>> >>>>>>>>>> Applied to u-boot/master, thanks! >>>>>>>>>> >>>>>>>>> >>>>>>>>> This breaks booting on my board (am3352, eMMC boot, FIT u-boot, >>>>>>>>> CONFIG_SPL_LOAD_FIT). Not got any useful diagnostics - if I boot it >>>>>>>>> from eMMC I get nothing at all on the console, if I boot over ymodem >>>>>>>>> it stalls at 420k, before continuing to 460k. My guess is there's some >>>>>>>>> error going to the console at the 420k mark, but obviously it's lost >>>>>>>>> in the ymodem... I have two DTBs in the FIT image, 420k would about >>>>>>>>> align to the point between them. >>>>>>>> >>>>>>>> My bet would be on some padding / unaligned access problem that this >>>>>>>> patch uncovered. Can you take a look ? >>>>>>> >>>>>>> Seems plausible. With this change my external data starts at 0x483 and >>>>>>> everything after it is non-aligned: >>>>>> >>>>>> Should the beginning of external data be aligned ? >>>>> >>>>> If in U-Boot we revert e8c2d25845c72c7202a628a97d45e31beea40668 does the >>>>> problem go away? If so, that's not a fix outright, it means we need to >>>>> dig back in to the libfdt thread and find the "make this work without >>>>> killing performance everywhere all the time" option. >>>> >>>> Still, my question is, should the beginning of external data be aligned >>>> ? And if so, to what, 4 bytes like FDT entries OR 8 bytes to cater for >>>> arm64/rv64 ? >>> >>> Is "external data" the kernel in this case? If so, I swear Linux >>> mandates 8 byte alignment for arm32 as well. >> >> External data can be anything, and if it is supposed to be 8 bytes, we >> already failed at that since forever. > > I would be entirely unsurprised at things working through a combination > of luck and co-incidence in our previous padding working out. So, what > typically is "external data" in this context? Anything you can bundle into the fitImage, -E just puts the content at the end of the fitImage and places a reference into the fitImage itself.