[Bug libc/17176] New: backtrace() not working on ARMv7a

["prafulla.fin at gmail dot com" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=17176

            Bug ID: 17176
           Summary: backtrace() not working on ARMv7a
           Product: glibc
           Version: 2.18
            Status: NEW
          Severity: normal
          Priority: P2
         Component: libc
          Assignee: unassigned at sourceware dot org
          Reporter: prafulla.fin at gmail dot com
                CC: drepper.fsp at gmail dot com

Created attachment 7716
  --> https://sourceware.org/bugzilla/attachment.cgi?id=7716&action=edit
c file to simulate the error.

Hi,

I am trying to generate a call stack trace using backtrace() API which is part
of libbacktrace. The idea is to catch a SIGSEGV signal and call backtrace() to
print all the address values and compare the obtained addresses from objdump -D
of executable. Attached is a simplified version of the application. Following
is the output seen on ARMv7a platform with buildroot cross-toolchain (gcc-
4.8.2, binutis-2.18.1).

To compile the application:
${CROSS_COMPILE}gcc -o crash_test -O0 -funwind-tables -rdynamic crash_test.c

ARMv7a# ./crash_test
Trying to access NULL pointer!
SIGSEGV Handler!
Got Backtrace Size=2
0x00008724
0x000087c4
ARMv7a#

The above function call trace is only that of the signal hander
(print_back_trace, sigsegv_handler) and does not show the entire call stack for
the function where program crashed (print_back_trace, sigsegv_handler, func2,
main).

On x86 host same program shows a deeper function call trace right up to the
main function and even beyond:
x86-RHEL5-host$./crash_test
Trying to access NULL pointer!
SIGSEGV Handler!
Got Backtrace Size=7
0x00400939
0x004009ab
0x30930302f0
0x004009d3
0x00400a7b
0x309301d994
0x00400889
x86-RHEL5-host$

Can someone please comment on what is going wrong. Any special flags that need
to be used while compiling/linking the program.

http://lists.uclibc.org/pipermail/uclibc/2013-September/047932.html

Similar issue in uclibc was solved by creating a patch to uclibc files, can
some one let me know if there is any existing patch is available for glibc
similar to this?, if not can anyone help me in providing the similar patch for
glibc.

Please let me know if i can provide any info.

/Thanks
Prafulla

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