Debug Kernel Modules With KGDB

Freeman Zhang freeman.zhang1992 at gmail.com
Mon Dec 1 06:30:42 EST 2014


Hi Raghavendra,

Yes, you are right, 'sudo' isn't implemented in android. However, `su`
enable me to read the .text as root. It's the same, 0x00000000.

So I guess something else should be wrong.


Thanks anyway!

Freeman Zhang

-------- Original Message --------
> Hi Zhang,
> 
> On Monday 01 December 2014 04:32 PM, Freeman Zhang wrote:
>> Hi Raghavendra,
>>
>> Thanks for your reply, but `sudo` doesn't solve the problem :(
> Well then I guess 'sudo' isn't implemented in android. Any way,
> ultimately you may wan't to login as root and then try reading the file
> in order to get the address.
> Regards,
> Raghavendra
>>
>> All the best!
>>
>> Freeman Zhang
>>
>> -------- Original Message --------
>>> On Monday 01 December 2014 03:26 PM, Freeman Zhang wrote:
>>>> Hi list,
>>>>
>>>> I've been trying to setup a debug environment for linux
>>>> kernel(v3.4,Android,ARM) with kgdb. It worked fine untill I tried to
>>>> use
>>>> it to debug a module. Under the instruction from LDD, I add module
>>>> debug
>>>> info in gdb with command:
>>>>
>>>>      add-symbol-file test-module.ko  address
>>>>
>>>> LDD uses `cat /sys/module/test-module/sections/.text` to get the
>>>> address
>>>> where the module has been loaded. However, I got:
>>>>           0x00000000
>>> Try reading the file as a root.
>>> $ sudo cat /sys/module/test-module/sections/.text
>>>> When I use `lsmod`, I got:
>>>>
>>>>      test-module 15278 0 - Live 0x00000000 (O)
>>>>
>>>> Why nothing but 0x00000000 ??
>>>>
>>>> So I have to do some research in kernel/module.c, and find out that
>>>> struct module -> module_core = 0xbf000000. But when I try these in gdb:
>>>>
>>>>      add-symbol-file test-module.ko  0xbf000000
>>>>      break one_of_my_function
>>>>
>>>> I got:
>>>>
>>>>      Cannot access memory at address 0xbf002350
>>>>
>>>> :(
>>>> Could somebody help?
>>>>
>>>>
>>>> All the best!
>>>> Freeman Zhang
>>>>
>>>>          
>>>>
>>>>
>>>>
>>>> _______________________________________________
>>>> Kernelnewbies mailing list
>>>> Kernelnewbies at kernelnewbies.org
>>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>>>
>>> -------------------------------------------------------------------------------------------------------------------------------
>>>
>>>
>>> [ C-DAC is on Social-Media too. Kindly follow us at:
>>> Facebook: https://www.facebook.com/CDACINDIA & Twitter: @cdacindia ]
>>>
>>> This e-mail is for the sole use of the intended recipient(s) and may
>>> contain confidential and privileged information. If you are not the
>>> intended recipient, please contact the sender by reply e-mail and
>>> destroy
>>> all copies and the original message. Any unauthorized review, use,
>>> disclosure, dissemination, forwarding, printing or copying of this email
>>> is strictly prohibited and appropriate legal action will be taken.
>>> -------------------------------------------------------------------------------------------------------------------------------
>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> Kernelnewbies mailing list
>>> Kernelnewbies at kernelnewbies.org
>>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>>>
> 
> 
> -------------------------------------------------------------------------------------------------------------------------------
> 
> [ C-DAC is on Social-Media too. Kindly follow us at:
> Facebook: https://www.facebook.com/CDACINDIA & Twitter: @cdacindia ]
> 
> This e-mail is for the sole use of the intended recipient(s) and may
> contain confidential and privileged information. If you are not the
> intended recipient, please contact the sender by reply e-mail and destroy
> all copies and the original message. Any unauthorized review, use,
> disclosure, dissemination, forwarding, printing or copying of this email
> is strictly prohibited and appropriate legal action will be taken.
> -------------------------------------------------------------------------------------------------------------------------------
> 
> 

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: OpenPGP digital signature
Url : http://lists.kernelnewbies.org/pipermail/kernelnewbies/attachments/20141201/be2301f2/attachment.bin 


More information about the Kernelnewbies mailing list