[Crash-utility] source line numbers and modules

[Dave Anderson]

Alan Tyson wrote:
> Hi,
> 
> Could someone please explain why we cannot get source line numbers when 
> disassembling modules?  Is the problem missing functionality in 
> store_load_module_symbols() or is there an inherent limitation with the 
> gdb linked in with crash in that it cannot accept additional debug_line 
> information for modules?  I ask because gdb has this functionality for 
> user-space shared libraries and it seems to work OK.  Or am I missing 
> something which is much more complex?
> 
> Thanks,
> 
> Alan Tyson,
> Hewlett-Packard.

What architecture?

I'm presuming that you're running the "mod" command to load
the debuginfo data from the target module:

# crash
...
crash> dis -l ext3_count_dirs
0xe08aa000 <ext3_count_dirs>:   push   %edi
0xe08aa001 <ext3_count_dirs+1>: mov    %eax,%edi
0xe08aa003 <ext3_count_dirs+3>: push   %esi
0xe08aa004 <ext3_count_dirs+4>: xor    %esi,%esi
0xe08aa006 <ext3_count_dirs+6>: push   %ebx
0xe08aa007 <ext3_count_dirs+7>: xor    %ebx,%ebx
0xe08aa009 <ext3_count_dirs+9>: jmp    0xe08aa021
0xe08aa00b <ext3_count_dirs+11>:        xor    %ecx,%ecx
0xe08aa00d <ext3_count_dirs+13>:        mov    %ebx,%edx
0xe08aa00f <ext3_count_dirs+15>:        mov    %edi,%eax
0xe08aa011 <ext3_count_dirs+17>:        call   0xe08a809b <ext3_get_group_desc>
0xe08aa016 <ext3_count_dirs+22>:        test   %eax,%eax
0xe08aa018 <ext3_count_dirs+24>:        je     0xe08aa020
0xe08aa01a <ext3_count_dirs+26>:        movzwl 0x10(%eax),%eax
0xe08aa01e <ext3_count_dirs+30>:        add    %eax,%esi
0xe08aa020 <ext3_count_dirs+32>:        inc    %ebx
0xe08aa021 <ext3_count_dirs+33>:        mov    0x160(%edi),%eax
0xe08aa027 <ext3_count_dirs+39>:        cmp    0x24(%eax),%ebx
0xe08aa02a <ext3_count_dirs+42>:        jb     0xe08aa00b
0xe08aa02c <ext3_count_dirs+44>:        mov    %esi,%eax
0xe08aa02e <ext3_count_dirs+46>:        pop    %ebx
0xe08aa02f <ext3_count_dirs+47>:        pop    %esi
0xe08aa030 <ext3_count_dirs+48>:        pop    %edi
0xe08aa031 <ext3_count_dirs+49>:        ret
crash> mod -s ext3
  MODULE   NAME                  SIZE  OBJECT FILE
e08c4f80  ext3                123337 
/lib/modules/2.6.18-53.el5/kernel/fs/ext3/ext3.ko
crash> dis -l ext3_count_dirs
/usr/src/debug/kernel-2.6.18/linux-2.6.18.i686/fs/ext3/ialloc.c: 746
0xe08aa000 <ext3_count_dirs>:   push   %edi
0xe08aa001 <ext3_count_dirs+1>: mov    %eax,%edi
0xe08aa003 <ext3_count_dirs+3>: push   %esi
0xe08aa004 <ext3_count_dirs+4>: xor    %esi,%esi
0xe08aa006 <ext3_count_dirs+6>: push   %ebx
0xe08aa007 <ext3_count_dirs+7>: xor    %ebx,%ebx
0xe08aa009 <ext3_count_dirs+9>: jmp    0xe08aa021 <ext3_count_dirs+33>
/usr/src/debug/kernel-2.6.18/linux-2.6.18.i686/fs/ext3/ialloc.c: 751
0xe08aa00b <ext3_count_dirs+11>:        xor    %ecx,%ecx
0xe08aa00d <ext3_count_dirs+13>:        mov    %ebx,%edx
0xe08aa00f <ext3_count_dirs+15>:        mov    %edi,%eax
0xe08aa011 <ext3_count_dirs+17>:        call   0xe08a809b <ext3_get_group_desc>
/usr/src/debug/kernel-2.6.18/linux-2.6.18.i686/fs/ext3/ialloc.c: 752
0xe08aa016 <ext3_count_dirs+22>:        test   %eax,%eax
0xe08aa018 <ext3_count_dirs+24>:        je     0xe08aa020 <ext3_count_dirs+32>
/usr/src/debug/kernel-2.6.18/linux-2.6.18.i686/fs/ext3/ialloc.c: 754
0xe08aa01a <ext3_count_dirs+26>:        movzwl 0x10(%eax),%eax
0xe08aa01e <ext3_count_dirs+30>:        add    %eax,%esi
/usr/src/debug/kernel-2.6.18/linux-2.6.18.i686/fs/ext3/ialloc.c: 750
0xe08aa020 <ext3_count_dirs+32>:        inc    %ebx
0xe08aa021 <ext3_count_dirs+33>:        mov    0x160(%edi),%eax
0xe08aa027 <ext3_count_dirs+39>:        cmp    0x24(%eax),%ebx
0xe08aa02a <ext3_count_dirs+42>:        jb     0xe08aa00b <ext3_count_dirs+11>
/usr/src/debug/kernel-2.6.18/linux-2.6.18.i686/fs/ext3/ialloc.c: 757
0xe08aa02c <ext3_count_dirs+44>:        mov    %esi,%eax
0xe08aa02e <ext3_count_dirs+46>:        pop    %ebx
0xe08aa02f <ext3_count_dirs+47>:        pop    %esi
0xe08aa030 <ext3_count_dirs+48>:        pop    %edi
0xe08aa031 <ext3_count_dirs+49>:        ret
crash>