Debug Kernel Modules With KGDB

[Freeman Zhang]

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
>>>>
>>>>          
>>>>
>>>>
>>>>
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>>>> Kernelnewbies at kernelnewbies.org
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