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Re: stap is getting a segmentation fault on RHEL 5.1 bets

Frank Ch. Eigler wrote:
dwilder wrote:

[...] To recap my problem is that stap is getting a segmentation
fault on s390, RHEL5.1 beta.  This happens anytime I attempting to
probe modules.


Adding the -g flag did not add much more to the backtrace.  So I did
a little brute force troubleshooting.  What I found is that
dwarf_diename() is returning a bad pointer causing the segmentation

It could be an elfutils bug.

[...]  Any ideas?  I am going to try building new debug info files
and see if it helps.

You could also try elfutils 0.129.

- FChE

The problem only occurs when using the debuginfo files built from the kernel src.rpm. Here is what I did. Installed and built all the kernel rpms from kernel-2.6.18-48.el5.src.rpm (rpmbuild -ba). Installed the debug kernel and the associated debuginfo and kernel devel rpms. (note I chose the debug kernel but the problem happens on the non-debug kernel also.)

I ran stap probing a function in the qdio module, stap faulted!
I replace the qdio.ko.debug file in /usr/lib/debug... with the
qdio.ko file left over in the rpm build directory (/usr/src/redhat/BUILD/kernel...).

Now when I run my stap scrip it works fine. It looks like the rpm build is doing something to the debuginfo files. The sizes are slightly different, but not as small as the running module in /lib/modules.

ls -l qdio*
-rw-r--r-- 1 root root 1373490 Oct  3 10:27 qdio.ko.debug
-rwxr--r-- 1 root root 1199376 Oct  2 20:56 qdio.ko.debug.orig

file qdio*
qdio.ko.debug: ELF 64-bit MSB relocatable, IBM S/390, version 1 (SYSV), not stripped
qdio.ko.debug.orig: ELF 64-bit MSB relocatable, IBM S/390, version 1 (SYSV), not stripped

Any idea what rpmbuild could be doing to the debuginfo files?
I looked through the kernel.spec file and found no clues, but I am unfamiliar with rpm spec files, so I may have missed something.

I have not tried upgrading elfutils yet as you suggested.

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