Bug 2182059

Summary:	eu-addr2line -i option to display inlined functions doesn't work with LTO (-flto) and Dwarf5
Product:	Red Hat Enterprise Linux 9	Reporter:	Mark Wielaard <mjw>
Component:	elfutils	Assignee:	Mark Wielaard <mjw>
elfutils sub component:	system-version	QA Contact:	Martin Cermak <mcermak>
Status:	CLOSED ERRATA	Docs Contact:	Petr Hybl <phybl>
Severity:	medium
Priority:	unspecified	CC:	casantos, lkuprova, mcermak, mjw, phybl, qe-baseos-tools-bugs, vikpatil, wcohen
Version:	9.2	Keywords:	Triaged
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	elfutils-0.189-1.el9	Doc Type:	Bug Fix
Doc Text:	.`eu-addr2line -C` now correctly recognizes other arguments Previously, when you used the `-C` argument in `eu-addr2line` command from `elfutils`, the following single character argument disappeared. Consequently, the `eu-addr2line -Ci` command behaved the same way as `eu-addr2line -C` while `eu-addr2line -iC` worked as expected. This bug has been fixed, and `eu-addr2line -Ci` now recognizes both arguments.	Story Points:	---
Clone Of:	2162495	Environment:
Last Closed:	2023-11-07 08:51:58 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:	2162495
Bug Blocks:

Description Mark Wielaard 2023-03-27 12:38:51 UTC

+++ This bug was initially created as a clone of Bug #2162495 +++

Description of problem:
eu-addr2line -i option to display inlined functions doesn't work with LTO (-flto) and Dwarf5

Version-Release number of selected component (if applicable):
elfutils-0.187-4.el8.x86_64 
gcc-toolset-11-elfutils-0.185-5.el8.x86_64

How reproducible:
every time

Steps to Reproduce:
1.From repro.sh found in repro_inlines.tgz

scl enable gcc-toolset-11 'gcc -O2 -flto -gdwarf-5 -g sample.c'

2.scl enable gcc-toolset-11 'eu-addr2line  -fCi -e a.out 0x401055'


Actual results:

"main
/mnt/data/RTVs/testIK8/elfutils/repro_inlines/sample.c:6:5"

Expected results:

# "FunctionToInline1
# /mnt/data/repro_inlines/sample.c:6
# FunctionToInline2
# /mnt/data/repro_inlines/sample.c:34
# FunctionToInline3
# /mnt/data/repro_inlines/sample.c:39
# FunctionToInline4
# /mnt/data/elfutils/repro_inlines/sample.c:43
# FunctionToInline5
# /mnt/data/repro_inlines/sample.c:47
# FunctionToInline6
# /mnt/data/repro_inlines/sample.c:51
# main
# /mnt/data/repro_inlines/sample.c:57
# "

Additional info:

--- Additional comment from Mark Wielaard on 2023-01-19 18:35:53 UTC ---

This is indeed an issue with eu-addr2line -i, also in upstream.
It doesn't seem to rely on the DWARF version with both gcc -O2 -flto -gdwarf-4 and -gdwarf-5 you don't actually get inlined subroutines.

It seems to be caused by including the -C flag:
  -C, --demangle[=ARG]       Show demangled symbols (ARG is always ignored)

Without it:

$ eu-addr2line -fi -e a.out 0x0000000000401055
FunctionToInline1 inlined at /tmp/repro_inlines/sample.c:34:5 in main
/tmp/repro_inlines/sample.c:6:5
FunctionToInline2
/tmp/repro_inlines/sample.c:34:5
FunctionToInline3
/tmp/repro_inlines/sample.c:39:5
FunctionToInline4
/tmp/repro_inlines/sample.c:43:5
FunctionToInline5
/tmp/repro_inlines/sample.c:47:5
FunctionToInline6
/tmp/repro_inlines/sample.c:51:5
main
/tmp/repro_inlines/sample.c:57:5

I'll investigate, it shouldn't matter whether or not we are demangling the symbols, but apparently it does.

Note that as a workaround you can probably use binutils addr2line which seems to work correctly with -fCi (at least upstream, and tested against binutils version 2.38)

--- Additional comment from Mark Wielaard on 2023-01-19 18:55:14 UTC ---

(In reply to Mark Wielaard from comment #1)
> It seems to be caused by including the -C flag:
>   -C, --demangle[=ARG]       Show demangled symbols (ARG is always ignored)
> 
> Without it:
> 
> $ eu-addr2line -fi -e a.out 0x0000000000401055
> FunctionToInline1 inlined at /tmp/repro_inlines/sample.c:34:5 in main
> /tmp/repro_inlines/sample.c:6:5
> FunctionToInline2
> /tmp/repro_inlines/sample.c:34:5
> FunctionToInline3
> /tmp/repro_inlines/sample.c:39:5
> FunctionToInline4
> /tmp/repro_inlines/sample.c:43:5
> FunctionToInline5
> /tmp/repro_inlines/sample.c:47:5
> FunctionToInline6
> /tmp/repro_inlines/sample.c:51:5
> main
> /tmp/repro_inlines/sample.c:57:5
> 
> I'll investigate, it shouldn't matter whether or not we are demangling the
> symbols, but apparently it does.

This is really an embarrassing bug. The problem is that -C takes an argument (which is always ignored).
The code simply treats anything as an argument, so if you use eu-readelf -fCi ... it takes that 'i' as argument to -C and ignores it.
So you don't get -i inlines...

The workaround is putting -C last (-fiC):

$ eu-addr2line -fiC -e a.out 0x0000000000401052
FunctionToInline1 inlined at /tmp/repro_inlines/sample.c:34:5 in main
/tmp/repro_inlines/sample.c:6:5
FunctionToInline2
/tmp/repro_inlines/sample.c:34:5
FunctionToInline3
/tmp/repro_inlines/sample.c:39:5
FunctionToInline4
/tmp/repro_inlines/sample.c:43:5
FunctionToInline5
/tmp/repro_inlines/sample.c:47:5
FunctionToInline6
/tmp/repro_inlines/sample.c:51:5
main
/tmp/repro_inlines/sample.c:57:5

--- Additional comment from Carlos Santos on 2023-01-20 13:43:57 UTC ---

The customer(In reply to Mark Wielaard from comment #2)
> (In reply to Mark Wielaard from comment #1)
> > It seems to be caused by including the -C flag:
> >   -C, --demangle[=ARG]       Show demangled symbols (ARG is always ignored)
> > 
> > Without it:
> > 
> > $ eu-addr2line -fi -e a.out 0x0000000000401055
> > FunctionToInline1 inlined at /tmp/repro_inlines/sample.c:34:5 in main
> > /tmp/repro_inlines/sample.c:6:5
> > FunctionToInline2
> > /tmp/repro_inlines/sample.c:34:5
> > FunctionToInline3
> > /tmp/repro_inlines/sample.c:39:5
> > FunctionToInline4
> > /tmp/repro_inlines/sample.c:43:5
> > FunctionToInline5
> > /tmp/repro_inlines/sample.c:47:5
> > FunctionToInline6
> > /tmp/repro_inlines/sample.c:51:5
> > main
> > /tmp/repro_inlines/sample.c:57:5
> > 
> > I'll investigate, it shouldn't matter whether or not we are demangling the
> > symbols, but apparently it does.
> 
> This is really an embarrassing bug. The problem is that -C takes an argument
> (which is always ignored).
> The code simply treats anything as an argument, so if you use eu-readelf
> -fCi ... it takes that 'i' as argument to -C and ignores it.
> So you don't get -i inlines...
> 
> The workaround is putting -C last (-fiC):
> 
> $ eu-addr2line -fiC -e a.out 0x0000000000401052
> FunctionToInline1 inlined at /tmp/repro_inlines/sample.c:34:5 in main
> /tmp/repro_inlines/sample.c:6:5
> FunctionToInline2
> /tmp/repro_inlines/sample.c:34:5
> FunctionToInline3
> /tmp/repro_inlines/sample.c:39:5
> FunctionToInline4
> /tmp/repro_inlines/sample.c:43:5
> FunctionToInline5
> /tmp/repro_inlines/sample.c:47:5
> FunctionToInline6
> /tmp/repro_inlines/sample.c:51:5
> main
> /tmp/repro_inlines/sample.c:57:5

The customer for whom we opened the bugs replied that the workaround does not work and I confirmed it:

$ rpm -q gcc-toolset-11
gcc-toolset-11-11.1-1.el8.x86_64

$ rpm -qf /bin/eu-addr2line
elfutils-0.187-4.el8.x86_64

$ scl enable gcc-toolset-11 'gcc -O2 -flto -gdwarf-5 -g sample.c'

$ scl enable gcc-toolset-11 'eu-addr2line  -fiC -e a.out 0x0000000000401052'
main
/work/XXXXXXXX/repro_inlines/sample.c:6:5

$ /bin/eu-addr2line  -fiC -e a.out 0x0000000000401052
main
/work/XXXXXXXX/repro_inlines/sample.c:6:5

--- Additional comment from Mark Wielaard on 2023-01-20 22:58:07 UTC ---

(In reply to Carlos Santos from comment #3)
> The customer for whom we opened the bugs replied that the workaround does
> not work and I confirmed it:
> 
> $ rpm -q gcc-toolset-11
> gcc-toolset-11-11.1-1.el8.x86_64
> 
> $ rpm -qf /bin/eu-addr2line
> elfutils-0.187-4.el8.x86_64
> 
> $ scl enable gcc-toolset-11 'gcc -O2 -flto -gdwarf-5 -g sample.c'
> 
> $ scl enable gcc-toolset-11 'eu-addr2line  -fiC -e a.out 0x0000000000401052'
> main
> /work/XXXXXXXX/repro_inlines/sample.c:6:5
> 
> $ /bin/eu-addr2line  -fiC -e a.out 0x0000000000401052

You are right.
I apparently hadn't tested with the -flto option, thinking that wasn't it. Sorry.
If you do use -flto then it really doesn't work with or without -C or placing it last.

I go and try to figure out what goes wrong when the binary is produced with -flto.
Upstream acts the same, so it isn't a RHEL specific bug.

--- Additional comment from Mark Wielaard on 2023-01-23 09:24:51 UTC ---

So there are two issues:

1) The demangle option -C prevents -i to work when used before it.
   So -Ci won't show inlines, but -iC does. Submitted an upstream patch to fix that:
   https://patchwork.sourceware.org/project/elfutils/patch/20230123091128.687801-1-mark@klomp.org/

2) The -i inlines option doesn't work when using -flto. This has now easy
   workaround. The issue is that with -flto the abstract origin of an inlined subroutine
   is in a separate "compile unit", which confused the libdw dwarf_getscopes function.
   Patch to fix that submitted upstream:
   https://patchwork.sourceware.org/project/elfutils/patch/20230123091520.688326-1-mark@klomp.org/

Comment 10 errata-xmlrpc 2023-11-07 08:51:58 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (elfutils bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2023:6609