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 <ma...@denx.de> wrote: > >>>> > >>>> On 5/5/20 3:22 PM, Alex Kiernan wrote: > >>>>> On Mon, May 4, 2020 at 12:28 PM Tom Rini <tr...@konsulko.com> 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 <ma...@denx.de> > >>>>>>> Reviewed-by: Simon Glass <s...@chromium.org> > >>>>>>> Cc: Heinrich Schuchardt <xypron.g...@gmx.de> > >>>>>>> Cc: Tom Rini <tr...@konsulko.com> > >>>>>> > >>>>>> 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. -- Tom
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