[Crash-utility] dis command not correct in crash [ARM]

[Per Fransson]

Hi,

>> Are you able to test with the same GDB version that is embedded in crash?
>>
>> I'm running out of ideas (I sure hope Per figures out what is going on :-)).
>
> Thanks for that vote of confidence =o)
>
> Alas, I must confess,
> all I have is a guess
> that "dot text" is partly a mess
> ...no less
>
> /Per
>
>> Are you able to make the vmlinux/vmcore pair available to us?
>>

Short version:
##############
It's the compressed kernel, including decompression stub, occupying
the first 0x3ffe00 bytes of .text

Long version:
#############
I extracted the .text parts of the vmlinux and dump and diffed:

vmlinux
-------
.text:
start: 0x0081c0 = 33216
size:  0x4a85d4 = 4883924
dd bs=1 count=4883924 skip=33216 if=vmlinux of=vmlinux_text

dump
----
.text:
start: 0xc01081c0 - 0xc0000000 + 0x94 = 1081940
size:  0x4a85d4 = 4883924
dd bs=1 count=4883924 skip=1081940 if=233_0128.dump of=dump_text

First I thought I had made a mistake, because, to begin with, it's all
different, but then, after 0x3ffe00 bytes (that'd correspond to
virtual address 0xc01081c0+0x3ffe00=0xc0507fc0 in crash), it's all
identical (except for __v7_setup_stack, which for some reason is
placed in .text.) This made me run 'string' on the data in those first
0x3ffe00 bytes of .text and they looked kind of familiar, for example:

   3baf  -- System halted
   3bc1 Attempting division by 0!
   3bdb Uncompressing Linux...
   3bf2 decompressor returned an error
   3c11  done, booting the kernel.

and that's when I realized it was the image from
arch/arm/boot/compressed. I think you've loaded a new (capture?)
kernel at the location where the original one was loaded before
pulling out the dump. I also predict there will be a cut-off point at
virtual address 0xc0507fc0, with all the code at lower addresses being
bad and everything else being ok.

If you need to you can probably replace those 0x3ffe00 bytes of the
dump with those from the vmlinux.

Regards,
Per

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