Re: [uml-devel] Am I doing something wrong with -skas0?

[Bodo Stroesser <bstroesser@fujitsu-siemens.com>]

Rob Landley wrote:
> On Wednesday 13 July 2005 07:11, Bodo Stroesser wrote:
> 
>>Rob Landley wrote:
>>
>>>Am I doing it right?  Is there anything I can do to help track this down?
>>>
>>>Rob
>>
>>The value of EIP reported in your earlier mail is quite surprising.
>>Could you please "objdump" vmlinux and send the part of
>>"stub_segv_handler"?
>>
>> Bodo
> 
> 
> I'm guessing you want objdump -d, and here's stub_segv_handler from that:
> 
> 081020b0 <stub_segv_handler>:
>  81020b0:       8b 44 24 5c             mov    0x5c(%esp),%eax
>  81020b4:       a3 04 f0 ff bf          mov    %eax,0xbffff004
>  81020b9:       8b 44 24 3c             mov    0x3c(%esp),%eax
>  81020bd:       a3 00 f0 ff bf          mov    %eax,0xbffff000
>  81020c2:       8b 44 24 38             mov    0x38(%esp),%eax
>  81020c6:       a3 08 f0 ff bf          mov    %eax,0xbffff008
>  81020cb:       b8 14 00 00 00          mov    $0x14,%eax
>  81020d0:       cd 80                   int    $0x80
>  81020d2:       89 c3                   mov    %eax,%ebx
>  81020d4:       b8 25 00 00 00          mov    $0x25,%eax
>  81020d9:       b9 0a 00 00 00          mov    $0xa,%ecx
>  81020de:       cd 80                   int    $0x80
>  81020e0:       58                      pop    %eax
>  81020e1:       58                      pop    %eax
>  81020e2:       58                      pop    %eax
>  81020e3:       b8 77 00 00 00          mov    $0x77,%eax
>  81020e8:       cd 80                   int    $0x80
>  81020ea:       c3                      ret
> 
> Rob
Hi Jeff,

stub_segv_handler misses the "push ebp" at the beginning. As you
do the normally corresponding "pop eax" explicitly, I think stack
pointer is wrong on call of sigreturn.

I have no idea, what makes happen this. Maybe it depends on compiler
version?

	Bodo

P.S.:
Normally, stub_segv_handler should look like this:

a02090d0 <stub_segv_handler>:
a02090d0:       55                      push   %ebp
a02090d1:       89 e5                   mov    %esp,%ebp
a02090d3:       8b 45 60                mov    0x60(%ebp),%eax
a02090d6:       a3 04 f0 ff bf          mov    %eax,0xbffff004
a02090db:       8b 45 40                mov    0x40(%ebp),%eax
a02090de:       a3 00 f0 ff bf          mov    %eax,0xbffff000
a02090e3:       8b 45 3c                mov    0x3c(%ebp),%eax
a02090e6:       a3 08 f0 ff bf          mov    %eax,0xbffff008
a02090eb:       b8 14 00 00 00          mov    $0x14,%eax
a02090f0:       cd 80                   int    $0x80
a02090f2:       89 c3                   mov    %eax,%ebx
a02090f4:       b8 25 00 00 00          mov    $0x25,%eax
a02090f9:       b9 0a 00 00 00          mov    $0xa,%ecx
a02090fe:       cd 80                   int    $0x80
a0209100:       58                      pop    %eax
a0209101:       58                      pop    %eax
a0209102:       58                      pop    %eax
a0209103:       b8 77 00 00 00          mov    $0x77,%eax
a0209108:       cd 80                   int    $0x80
a020910a:       5d                      pop    %ebp
a020910b:       c3                      ret


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