[Banana Pi] Fatal kernel mode data abort: 'Alignment Fault' on read

Lars Engels lars.engels at 0x20.net
Thu Nov 5 20:42:14 UTC 2015


On Thu, Nov 05, 2015 at 08:12:54PM +0100, Hans Petter Selasky wrote:
> On 11/05/15 16:34, Lars Engels wrote:
> > On Thu, Nov 05, 2015 at 01:14:11PM +0100, Hans Petter Selasky wrote:
> >> On 11/05/15 13:09, Lars Engels wrote:
> >>> On Thu, Nov 05, 2015 at 12:02:06PM +0100, Hans Petter Selasky wrote:
> >>>> On 11/05/15 11:48, Lars Engels wrote:
> >>>>> Using FreeBSD-armv6-11.0-A20-290366.img I can reproducible crash the
> >>>>> kernel by USB-tethering the Banana Pi to a mobile phone and run "
> >>>>> pkg bootstrap". It looks like this:
> >>>>>
> >>>>> root at bananapi:/ # pkg bootstrap
> >>>>> The package management tool is not yet installed on your system.
> >>>>> Do you want to fetch and install it now? [y/N]: y
> >>>>> Bootstrapping pkg from pkg+http://pkg.FreeBSD.org/FreeBSD:11:armv6/latest, please wait...
> >>>>> Fatal kernel mode data abort: 'Alignment Fault' on read
> >>>>> trapframe: 0xea576a90
> >>>>> FSR=00000001, FAR=c43a1d6e, spsr=60000113
> >>>>> r0 =00000014, r1 =0000003c, r2 =0000003c, r3 =00000903
> >>>>> r4 =00000000, r5 =c43a1d6a, r6 =00000028, r7 =c43a1d56
> >>>>> r8 =00000000, r9 =00000014, r10=00000028, r11=ea576bf8
> >>>>> r12=00000000, ssp=ea576b20, slr=c061aba4, pc =c04f68e8
> >>>>>
> >>>>> [ thread pid 13 tid 100024 ]
> >>>>> Stopped at      tcp_input+0x820:        ldr     r0, [r5, #0x004]
> >>>>
> >>>> Hi,
> >>>>
> >>>> Could you "objdump -Dx --source /boot/kernel/kernel" and figure out
> >>>> which code line "tcp_input+0x820" corresponds to?
> >>>
> >>> You mean like "objdump ... | grep -C10 tcp_input+0x820"?
> >>>
> >>> I started that half an hour ago and it's still not finished.
> >>>
> >>
> >> No, you need to find where tcp_input starts, by less-ing it, then add
> >> 0x820 to that address and then verify that the assembly instruction
> >> there matches.
> >
> > Ok, I have no idea what I am doing, but here's what I did:
> >   # objdump -Dx --source /boot/kernel/kernel --start-address="0xc04f51c8" --stop-address="0xC04F59E8"
> >
> > The result is a 1,3MB text file at:
> > http://bsd-geek.de/FreeBSD/objdump.txt
> >
> > Can you see anything there?
> >
> 
> Hi,
> 
> I cannot find "ldr r0, [r5, #4]" at the given location, though if that 
> is the faulting instruction, it might be related to an unaligned SACK 
> option. Can you test a new kernel with a patch?

I think I could build an image with crochet, so if you have a patch, I
can try.
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