Re: Bug in powerpc gdb?

[Francois Taiani <f.taiani@computer.org>]

Hi Royer,

I've encountered the same problem. It seems to be an issue with the 
newer version of gdb, but I don't know if it has been reported yet. Have 
you seen

http://sourceware.org/ml/gdb/2004-11/msg00060.html

for a nice small example?

The problem seems to be related to optimization and code relocation (PIC 
means position independant code if I'm correct).

Cheers

Francois

Roger Leigh wrote:
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> Hi folks,
>
> I've come across some stack corruption when debugging a program with
> gdb.  I thought this was a problem with my code, but it's (AFAICT)
> verifiably correct, and shows no stack corruption on i386.  As a
> result, I think this is a powerpc/gdb bug.
>
> Please could someone try to reproduce this on their powerpc system?
>
> Steps to reproduce:
> 1. Download testcase from
>    http://www.whinlatter.ukfsn.org/gtk/uterm-stacks-0.1.0.tar.bz2
> 2. Configure with
>    CC=c99 ./configure --prefix=/tmp/inst
> 3. make all install
> 4. cd utils
> 5. ./uterm-register [confirm the program runs OK]
> 6. Debug:
>
> rleigh@hardknott:/tmp/uterm-stacks-0.1.0/utils$ gdb .libs/uterm-register
> GNU gdb 6.3-debian
> [...]
> This GDB was configured as "powerpc-linux"...Using host libthread_db library "/lib/libthread_db.so.1".
>
> (gdb) break main
> Breakpoint 1 at 0x1000167c: file uterm-register.c, line 37.
> (gdb) break uterm_control_register_module
> Breakpoint 2 at 0x10011c8c
> (gdb) run
> Starting program: /tmp/uterm-stacks-0.1.0/utils/.libs/uterm-register
> Breakpoint 2 at 0xffaf1a4: file uterm-control.c, line 142.
>
> Breakpoint 1, main () at uterm-register.c:37
> 37        GModule *module = uterm_control_register_module("iso646-c0");
> (gdb) bt
> #0  main () at uterm-register.c:37
> (gdb) c
> Continuing.
>
> Breakpoint 2, uterm_control_register_module (module=0x7ffffb20 "")
>     at uterm-control.c:142
> 142       g_return_val_if_fail(module != NULL, NULL);
> (gdb) bt
> #0  uterm_control_register_module (module=0x7ffffb20 "")
>     at uterm-control.c:142
> #1  0x0ffaf19c in uterm_control_register_module (module=0x7ffffb20 "")
>     at uterm-control.c:141
> #2  0x0ffaf19c in uterm_control_register_module (module=0x7ffffb20 "")
>     at uterm-control.c:141
> #3  0x0ffaf19c in uterm_control_register_module (module=0x7ffffb20 "")
>     at uterm-control.c:141
> Previous frame inner to this frame (corrupt stack?)
>
> I'm fairly certain this is bogus.  This is current Debian unstable,
> with Linux 2.6.11.8.
>
>
> Regards,
> Roger
>
> - -- 
> Roger Leigh
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