Bug 16832 - Erroneous backtrace on avrxmega architectures
Summary: Erroneous backtrace on avrxmega architectures
Alias: None
Product: gdb
Classification: Unclassified
Component: backtrace (show other bugs)
Version: 7.7
: P2 normal
Target Milestone: ---
Assignee: Pierre Langlois
Depends on:
Reported: 2014-04-11 08:44 UTC by Pierre Langlois
Modified: 2014-04-11 09:34 UTC (History)
0 users

See Also:
Target: avr
Last reconfirmed:

Simple test program (52.79 KB, application/x-gzip)
2014-04-11 08:44 UTC, Pierre Langlois

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Description Pierre Langlois 2014-04-11 08:44:14 UTC
Created attachment 7548 [details]
Simple test program

Stack unwinding does not work properly for avrxmega architectures with more than 128k of flash memory.

This is due to GDB not being aware of avrxmega architectures, and defaulting having 2 bytes on the stack for the program counter when devices with more than 128k of memory store it in 3 bytes.

This GDB session was done with the axtenge256a3bu chip, debugged with AVaRice.

GNU gdb (AVR 8-bit toolchain (built 20140310))
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This GDB was configured as "--host=x86_64-unknown-linux-gnu --target=avr".
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(gdb) file atxmega-test.elf 
Reading symbols from atxmega-test.elf...done.
(gdb) target remote :4242
Remote debugging using :4242
0x00000000 in __vectors ()
(gdb) b multiply 
Breakpoint 1 at 0x21a: file main.c, line 8.
(gdb) c
Note: automatically using hardware breakpoints for read-only addresses.

Breakpoint 1, multiply (a=3, b=6) at main.c:8
8	  return a * b;
(gdb) bt
#0  multiply (a=3, b=6) at main.c:8
#1  0x0001f000 in ?? ()
(gdb) q
A debugging session is active.

	Inferior 1 [Remote target] will be killed.

Quit anyway? (y or n) 
Comment 1 Pierre Langlois 2014-04-11 08:46:52 UTC
Fixed by commit 9c97a0704e03c662b6afd92032c171fe6714b42d

Comment 2 cvs-commit@gcc.gnu.org 2014-04-11 09:34:59 UTC
This is an automated email from the git hooks/post-receive script. It was
generated because a ref change was pushed to the repository containing
the project "gdb and binutils".

The branch, gdb-7.7-branch has been updated
       via  999686dbc169a7beb0e7e88f5c76dca12174fdbf (commit)
      from  7456303a042711adee7c0ab3ec76df6e29616c88 (commit)

Those revisions listed above that are new to this repository have
not appeared on any other notification email; so we list those
revisions in full, below.

- Log -----------------------------------------------------------------

commit 999686dbc169a7beb0e7e88f5c76dca12174fdbf
Author: Pierre Langlois <pierre.langlois@embecosm.com>
Date:   Fri Mar 21 19:46:07 2014 +0000

    Erroneous backtrace on AVR.
    	PR backtrace/16721
    	PR backtrace/16832
    	* avr-tdep.c (struct gdbarch_tdep): Mention avrxmega in the comment.
    	(avr_gdbarch_init): Add xmega architectures given by bfd_architecture
    	when setting the size of call_length.
    	(avr_scan_prologue): Accept push r1 instruction for small stack
    	* MAINTAINERS (Write After Approval): Add "Pierre Langlois".


Summary of changes:
 gdb/ChangeLog   |   11 +++++++++++
 gdb/MAINTAINERS |    1 +
 gdb/avr-tdep.c  |   11 +++++++++--
 3 files changed, 21 insertions(+), 2 deletions(-)