Alignment crashes debugging?

[Sriram V]

Hi Russell,

Unfortunately, I cannot as my Android system needs those SGX to boot
up. It happens all of a sudden after a few hours or so.
I could not find any relavant kernel patches to fix that. Therefore, I
suspect it might be due to memory corruption.

Are you aware of any patches which might fix this issue as my kernel is old
Also, I wanted to check if kdump works on AM437x arm system and will
it help if i get and analyse the dump?

Regards,
Sriram

On Mon, Sep 18, 2017 at 8:14 PM, Russell King - ARM Linux
<linux at armlinux.org.uk> wrote:
> On Mon, Sep 18, 2017 at 08:08:43PM +0530, Sriram V wrote:
>> [147278.696759] Alignment trap: not handling instruction e1901f9f at [<c010ad10>]
>
> Quite a right objection by the kernel...
>
>> [147278.714884] Unhandled fault: alignment exception (0x001) at 0xffffff7f
>> [147278.725921] Internal error: : 1 [#1] PREEMPT SMP ARM
>> [147278.731321] Modules linked in: omaplfb(O) pvrsrvkm(O)
>> pruss_remoteproc remoteproc virtio virtio_ring
>> [147278.741197] CPU: 0 PID: 21706 Comm: zygote Tainted: G           O 3.12.20+ #1
>> [147278.748893] task: ea86ebc0 ti: ec6cc000 task.ti: ec6cc000
>> [147278.754749] PC is at __destroy_inode+0xfc/0x14c
>> [147278.759676] LR is at _raw_spin_unlock+0x30/0x50
>> [147278.764596] pc : [<c010ad14>]    lr : [<c06d8918>]    psr: a00f0013
>> [147278.764596] sp : ec6cdd40  ip : ec6cdcf0  fp : ec6cdd54
>> [147278.777007] r10: dc0e77e0  r9 : e13b0c90  r8 : dc0e7778
>> [147278.782663] r7 : c06ed8f4  r6 : c06ed8f4  r5 : ece67b80  r4 : ece67b28
>> [147278.789705] r3 : 00000000  r2 : ec6cdcf0  r1 : 00000000  r0 : ffffff7f
>>...
>> [147279.166953] Code: 0affffdf e3a03000 ee073fba e1901f9f (e2411001)
>
>    0:   0affffdf        beq     0xffffff84
>    4:   e3a03000        mov     r3, #0
>    8:   ee073fba        mcr     15, 0, r3, cr7, cr10, {5}
>    c:   e1901f9f        ldrex   r1, [r0]                ; <=====
>   10:   e2411001        sub     r1, r1, #1
>
> As we can see, r0 is 0xffffff7f, which is definitely incorrect.
>
> Does this happen if you omit loading the out-of-tree modules?
>
> --
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