Bug 1626614

Summary:	[LLNL 7.7 FEAT] readelf --unwind not supported
Product:	Red Hat Enterprise Linux 8	Reporter:	Ben Woodard <woodard>
Component:	binutils	Assignee:	Nick Clifton <nickc>
binutils sub component:	system-version	QA Contact:	qe-baseos-tools-bugs
Status:	CLOSED DUPLICATE	Docs Contact:
Severity:	medium
Priority:	unspecified	CC:	fweimer, jbastian, law, mprchlik, ohudlick, tgummels
Version:	8.2	Keywords:	FutureFeature, Triaged
Target Milestone:	rc
Target Release:	8.2
Hardware:	aarch64
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	1626622 1640745 (view as bug list)		Environment:
Last Closed:	2019-11-05 16:47:54 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1563291, 1593423, 1640745, 1746605

Description Ben Woodard 2018-09-07 17:48:03 UTC

Description of problem:
[ben@ulna2:~]$ readelf --unwind /usr/lib64/libm.so

The decoding of unwind sections for machine type AArch64 is not currently supported.


Version-Release number of selected component (if applicable):
binutils-2.27-28.base.el7_5.1.aarch64

How reproducible:
always

Steps to Reproduce:
see above.

Actual results:
The decoding of unwind sections for machine type AArch64 is not currently supported.


Expected results:
a dump of the .eh_frame section.

Additional info:
http://post-office.corp.redhat.com/archives/tools/2016-August/msg00054.html
May be slightly related to: https://bugzilla.redhat.com/enter_bug.cgi?product=Red%20Hat%20Enterprise%20Linux%207

Comment 2 Ben Woodard 2018-09-07 17:51:05 UTC

oops may be related to: https://bugzilla.redhat.com/show_bug.cgi?id=1626614

Comment 3 Ben Woodard 2018-09-07 19:49:15 UTC

Whoa this isn't just ARM evidently we can't process x86_64 either
[ben@Mustang ~]$ readelf -u /usr/lib64/libm.so.6 

The decoding of unwind sections for machine type Advanced Micro Devices X86-64 is not currently supported.

I thought it was just an ARM thing.

[ben@Mustang ~]$ rpm -q binutils
binutils-2.29.1-23.fc28.x86_64

Comment 4 Ben Woodard 2018-09-07 20:05:49 UTC

Useful information on how to read the .eh_frame section:
https://www.airs.com/blog/archives/460

Maybe the best plan is to extend readelf to process the .eh_frame sections for unwind info.

Comment 5 Ben Woodard 2018-09-11 00:48:32 UTC

A workaround is readelf -wF or -wf however, it is unclear to me why -u isn't wired up to do the same thing as -wf. Is that something worth considering?

Comment 6 Nick Clifton 2018-09-18 16:15:11 UTC

Hi Ben,

  Would you be terribly upset if I delayed this bug to say RHEL 7.7 ?

  It is a new feature request and I would prefer to have the feature
  implemented upstream first and then backported once it has been
  tested a bit...

Cheers
  Nick

Comment 7 Ben Woodard 2018-09-18 19:45:48 UTC

(In reply to Nick Clifton from comment #6)
> Hi Ben,
> 
>   Would you be terribly upset if I delayed this bug to say RHEL 7.7 ?

For this one — not a problem.

> 
>   It is a new feature request and I would prefer to have the feature
>   implemented upstream first and then backported once it has been
>   tested a bit...
> 
> Cheers
>   Nick

Comment 8 Ben Woodard 2018-10-18 16:22:11 UTC

The reason for this bug is that there is evidently a problem with the AARCH64 unwind information in some cases and the information doesn't match the .eh_frame debug data. I was hoping to use this feature to help debug the problem. I was unable to spot the problem when I was doing some testing and so the customer promised me a reproducer but got tied up with other problems. So the original problem report is on hold for the time being.

Even having a prototype decoder would be helpful when this problem report pops back up again.

Comment 10 Nick Clifton 2019-11-05 16:47:54 UTC


*** This bug has been marked as a duplicate of bug 1640745 ***