From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Rini Date: Tue, 5 May 2020 14:06:48 -0400 Subject: [PATCH V2] mkimage: fit: Do not tail-pad fitImage with external data In-Reply-To: <2fafc257-b22c-9eda-2cd3-53eefcd09a0d@denx.de> 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> Message-ID: <20200505180648.GZ12564@bill-the-cat> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de 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? -- Tom -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 659 bytes Desc: not available URL: