lkml.org 
[lkml]   [2008]   [Sep]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: v2.6.27-rc7: x86: #GP on panic?
Ingo Molnar wrote:
> * Vegard Nossum <vegard.nossum@gmail.com> wrote:
>
>> Hi,
>>
>> With 2.6.27-rc7 on qemu-x86_64, it seems that panic will trigger a
>> General Protection Fault. I haven't seen it before.
>
>> [ 4.523641] Code: eb fd 55 48 89 e5 53 51 83 3d 25 e8 78 00 00 75
>> 1a 31 d2 31 f6 48 c7 c7 e1 9c 01 81 e8 f7 a4 03 00 9c 5b fa e8 94 09
>> 00 00 53 9d <5a> 5b c9 c3 55 31 c0 48 89 e5 89 04 25 b0 c0 5f ff 65 83
>> 04 25
>
> hm, 0x5a is a simple pop %rdx. A #GP there means the stack segment is
> bust?
>

No, that would be #SS (and segments don't really exist in 64-bit mode
anyway.) In 32-bit mode it could mean a code segment overrun.

*However*...

[ 4.523477] general protection fault: fff2 [1] SMP

There is an error code attached to the #GP, which is supposed to mean
that somehow a segment selector was involved. This doesn't look like a
very valid segment selector at all.

> hm:
>
>> ffffffff8101a6b9 <disable_local_APIC>
>> ffffffff81019d25: 53 push %rbx
>> ffffffff81019d26: 9d popfq
>> ffffffff81019d27: 5a pop %rdx
>
> so it's preceded by a popfq and on the next instruction we #GP.
>
> but the stack and flags state looks good:
>
> [ 4.523641] RSP: 0018:ffff880007867d70 EFLAGS: 00000286
>

My guess is that the popfq enables interrupts, and we try to take an
interrupt through an IDT entry which isn't set up correctly.

-hpa



\
 
 \ /
  Last update: 2008-09-25 10:57    [W:0.606 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site