Debug Kernel Modules With KGDB

[Raghavendra]

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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