From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marek Vasut Date: Tue, 5 May 2020 19:53:42 +0200 Subject: [PATCH V2] mkimage: fit: Do not tail-pad fitImage with external data In-Reply-To: <20200505175022.GW12564@bill-the-cat> References: <20200501154026.79169-1-marex@denx.de> <20200504112749.GE12564@bill-the-cat> <20200505175022.GW12564@bill-the-cat> Message-ID: 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 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 ?