Re: cannot find bounds of function error

[vijay nag <vijunag at gmail dot com>]

On Wed, Jul 24, 2013 at 6:58 PM, vijay nag <vijunag@gmail.com> wrote:
> On Wed, Jul 24, 2013 at 6:19 PM, vijay nag <vijunag@gmail.com> wrote:
>>
>>
>> On Wednesday, July 24, 2013, Jan Kratochvil <jan.kratochvil@redhat.com>
>> wrote:
>>> On Wed, 24 Jul 2013 11:44:15 +0200, vijay nag wrote:
>>>> My latest gdb-7.5  barfs out  "cannot find bounds of current function"
>>>> error when it encounters GNU_IFUNC while executing one line of code at
>>>> a time using "next" command
>>>
>>> Sorry I did not analyze exactly your case but ensure your glibc contains
>>> this
>>> patch fixing how GDB deals with gnu-ifuncs:
>>>
>>>         commit f85fa27058eb7d4b56b8deaf885064cf8d730f68
>>>         Author: H.J. Lu <hjl.tools@gmail.com>
>>>         Date:   Thu Aug 9 16:04:37 2012 -0700
>>>             Avoid DWARF definition DIE on ifunc symbols
>>>
>>> Besides that there is already stable gdb-7.6 but I do not know about any
>>> specific change there for gnu-ifunc.
>>>
>>>
>>> Jan
>>>
>> Nice to hear from you again and I appreciate your quick turn-around. I shall
>> patch the changes to my glibc and check if that is just enough for the
>> gdb-7.5 to get going.
>>
>> Thanks
>
>
> I do see the patch in my glibc-2.17. What could be the issue here ?

Jan,

First of all,  glibc-2.17 seems to be having the fix that you mentioned.

Second of all, I upgraded gdb to 7.6 and still encountering the same problem.

Gdb is confused when the program jumps to PLT in-order to execute
GNU-IFUNC and any number of "Next" command will not make the program
proceed any further.

(gdb) p $eip
$1 = (void (*)()) 0x8048430
(gdb) n
Cannot find bounds of current function
(gdb) n
Cannot find bounds of current function
(gdb) n
Cannot find bounds of current function
(gdb) display $eip

1: $eip = (void (*)()) 0x8048430
(gdb)
(gdb) n
Cannot find bounds of current function
(gdb) n
Cannot find bounds of current function
(gdb) n
Cannot find bounds of current function
(gdb) n
Cannot find bounds of current function
(gdb) p $eip
$2 = (void (*)()) 0x8048430
(gdb)


I was looking the code diff of "step_once" function in the version 7.6 and 6.3

infcmd.c
       const char *name;

        if (find_pc_partial_function (pc, &name,
              &tp->control.step_range_start,
              &tp->control.step_range_end) == 0)
    error (_("Cannot find bounds of current function"));

        target_terminal_ours ();
        printf_filtered (_("Single stepping until exit from function %s,"
         "\nwhich has no line number information.\n"),
             name);
      }

Earlier version had  a plain printf for the error line, where as in
the newer versions it has been replaced by error_() which seems to be
unwinding the current gdb stack by doing a long-jump.  Any statements
after error() are superfluously existing without any effect.