gdbserver, find_extend_vma(), and VM_GROWSDOWN

gdbserver, find_extend_vma(), and VM_GROWSDOWN

[Kent Borg]

I am having gdbserver problems.  I can run gdbserver and attach to it
with gdb, but the peeks into the application space are failing.

For example, in debugging the peek for the first instruction of my
application, there is a call to find_extend_vma() (in mm/mmap.c).  The
test for:

  vma->vm_start <= addr

fails, and as this vms is VM_GROWSUP (and not VM_GROWSDOWN), the next
if-statement returns a NULL.  That percolates up until ptrace returns
zero.

This application code runs pretty well without gdbserver, what should
I look for next?  Is it indeed perverse for the addr to be below the
start?  Who is likely to blame for that?  Where should I look next?
Do I start grepping for every instance of PT_PTRACED in arch/ppc?


Thanks,

-kb, the Kent whose gdbserver Makefile says it is 4.12.3, and whose
kernel is quite close to 2.4.21.rc1.

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Re: gdbserver, find_extend_vma(), and VM_GROWSDOWN

[Wolfgang Denk]

In message <20030707120523.B4527@borg.org> you wrote:
>
> I am having gdbserver problems.  I can run gdbserver and attach to it
> with gdb, but the peeks into the application space are failing.

Where did you get your (Cross-) GDB and  gdbserver  from,  and  which
versions are these?


Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
We have phasers, I vote we blast 'em!
	-- Bailey, "The Corbomite Maneuver", stardate 1514.2

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Re: gdbserver, find_extend_vma(), and VM_GROWSDOWN

[Wolfgang Denk]

In message <200307071642.h67GguN01169@hyper.wm.sps.mot.com> you wrote:
>
> >Where did you get your (Cross-) GDB and  gdbserver  from,  and  which
> >versions are these?
>
> I pulled those together for Kent.  The gdb is gdb-5.3, and the gdbserver
> is from gdb-5.3/gdb/gdbserver, both configured for ppc-linux.

Did you try GDB/gdbserver from the ELDK?


Best regards,

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
Too much of anything, even love, isn't necessarily a good thing.
	-- Kirk, "The Trouble with Tribbles", stardate 4525.6

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Re: gdbserver, find_extend_vma(), and VM_GROWSDOWN

[Wolfgang Denk]

In message <200307071705.h67H5MD01399@hyper.wm.sps.mot.com> you wrote:
>
> >Did you try GDB/gdbserver from the ELDK?
>
> No.

Try it, then.

> Where did the gdbserver in ELDK come from and how is it different from
> gdbserver from gdb-5.3?

It's based on GDB-5.1, and we fixed a couple of problems.



Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
"In matters of principle, stand like a rock;  in  matters  of  taste,
swim with the current."                            - Thomas Jefferson

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