From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Kiernan Date: Wed, 6 May 2020 16:43:48 +0100 Subject: [PATCH V2] mkimage: fit: Do not tail-pad fitImage with external data In-Reply-To: References: <20200505175022.GW12564@bill-the-cat> <1073087038ce37a09715bcb5054c7931@walle.cc> <20200506134857.GE12564@bill-the-cat> <20200506142754.GH12564@bill-the-cat> <04369d83-daef-03c3-7a9e-7a6c83f9a5a3@denx.de> <20200506143724.GI12564@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 Wed, May 6, 2020 at 3:41 PM Marek Vasut wrote: > > On 5/6/20 4:37 PM, Tom Rini wrote: > > On Wed, May 06, 2020 at 04:33:37PM +0200, Marek Vasut wrote: > >> On 5/6/20 4:27 PM, Tom Rini wrote: > >>> On Wed, May 06, 2020 at 04:17:35PM +0200, Marek Vasut wrote: > >>>> On 5/6/20 3:48 PM, Tom Rini wrote: > >>>>> On Tue, May 05, 2020 at 11:17:19PM +0200, Michael Walle wrote: > >>>>>> Hi all, > >>>>>> > >>>>>> Am 2020-05-05 20:41, schrieb Simon Glass: > >>>>>>> Hi Tom, > >>>>>>> > >>>>>>> On Tue, 5 May 2020 at 11:50, 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. > >>>>>>> > >>>>>>> If it is a device tree, it must be 32-bit aligned. > >>>>>> > >>>>>> This commit actually breaks my board too (which I was just about to send > >>>>>> upstream, but realized it was broken). > >>>>>> > >>>>>> Said board uses SPL and main U-Boot. SPL runs fine and main u-boot doesn't > >>>>>> output anything. The only difference which I found is that fit-dtb.blob is > >>>>>> 2 bytes shorter. And the content is shifted by one byte although > >>>>>> data-offset is the same. Strange. In the non-working case, the inner > >>>>>> FDT magic isn't 4 byte aligned. > >>>>>> > >>>>>> You can find the two fit-dtb.blobs here: > >>>>>> > >>>>>> https://walle.cc/u-boot/fit-dtb.blob.working > >>>>>> https://walle.cc/u-boot/fit-dtb.blob.non-working > >>>>>> > >>>>>> > >>>>>> Reverting e8c2d25845c72c7202a628a97d45e31beea40668 doesn't help (I might > >>>>>> reverted it the wrong way, there is actually a conflict). > >>>>>> > >>>>>> I'll dig deeper into that tomorrow, but maybe you have some pointers where > >>>>>> to look. > >>>>>> > >>>>>> For reference you can find the current patch here: > >>>>>> https://github.com/mwalle/u-boot/tree/sl28-upstream > >>>>> > >>>>> I think we have a few things to fix here. Marek's patch is breaking > >>>>> things and needs to be reverted. But it's showing a few underlying > >>>>> problems that need to be fixed too: > >>>>> - fit_extract_data() needs to use calloc() not malloc() so that we don't > >>>>> leak random data. > >>>>> - We need to 8-byte alignment on the external data. That's the > >>>>> requirement for Linux for device trees on both 32 and 64bit arm. > >>>>> Atish, does RISC-V require more than that? I don't see it in Linux's > >>>>> Documentation/riscv/boot-image-header.rst (and there's no booting.rst > >>>>> file like arm/arm64). > >>>> > >>>> Why 8-byte alignment ? The external data are copied into the target > >>>> location, so why do they need to be padded in any way? > >>> > >>> The start of the external data needs the alignment, to be clearer. > >> > >> Why ? > > > > Given that things which end up in external data have alignment > > requirements, we need to align and meet those requirements. And I noted > > why 8 above. > > If you end up with external data, then you need to move those blobs into > their target location anyway. That's what you specify in the load = <> > property in the .its . > Just reading common/spl/spl_fit.c, I think that'll try and parse in situ, rather than relocating it? -- Alex Kiernan