Re: [m68k] res_init segfault, need help debugging

[Richard <rz@linux-m68k.org>]

On Sun, Jan 30, 2011 at 08:31:44PM +0000, Thorsten Glaser wrote:
> Dixi quod…
> 
> >ara2:~# cat >x.c
> >#include <netinet/in.h>
> >#include <arpa/nameser.h>
> >#include <resolv.h>
> >
> >int
> >main(void)
> >{
> >	return (res_init());
> >}
> >ara2:~# gcc x.c
> >ara2:~# ./a.out
> >Segmentation fault
> 
> >Basically, the segfault is on accessing _res.retrans
> >in line 67 (first access of _res)
> 
> Now, _res is at 0xc014ce58 and the code in question is:
> 
>    0xc00f1eb4 <__res_init>:     linkw %fp,#0
>    0xc00f1eb8 <__res_init+4>:   moveml %d2-%d5/%a2/%a5,%sp@-
>    0xc00f1ebc <__res_init+8>:   lea %pc@(0xc0148000),%a5
>    0xc00f1ec4 <__res_init+16>:  movel %a5,%d5
>    0xc00f1ec6 <__res_init+18>:  addil #9916,%d5
>    0xc00f1ecc <__res_init+24>:  movel %d5,%sp@-
>    0xc00f1ece <__res_init+26>:  movel %d5,%sp@
>    0xc00f1ed0 <__res_init+28>:  bsrl 0xc0040aa0 <__tls_get_addr@plt>
>    0xc00f1ed6 <__res_init+34>:  addql #4,%sp
> => 0xc00f1ed8 <__res_init+36>:  moveal %a0@,%a2

a0 is the plt addre returned by  bsrl 0xc0040aa0 and obviously does not
point to a valid address.

> If I read that right, it’s the equivalent of: mov a2,dword ptr [a0]

a0=tls_get_addr@plt(...)
a2=*(a0) 
in c-like pseudocode, but I do not know enough to make sense of the args to
tls_get_addr@plt.


Richard

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