Bug 162545

Summary:	wrong dwarf register numbers generated
Product:	Red Hat Enterprise Linux 4	Reporter:	Ulrich Drepper <drepper>
Component:	binutils	Assignee:	Jakub Jelinek <jakub>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	4.0
Target Milestone:	---
Target Release:	---
Hardware:	x86_64
OS:	Linux
URL:	http://sources.redhat.com/ml/binutils/2005-05/msg00243.html
Whiteboard:
Fixed In Version:	RHSA-2005-673	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2005-10-05 12:44:47 UTC	Type:	---
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:	156322

Description Ulrich Drepper 2005-07-06 04:02:50 UTC

Description of problem:
The assembler currently generated incorrect dwarf register numbers if symbolic
register names are used in cfi instructions.  This is on x86-64 only.  I expect
that ISVs will start using unwind info now since it is much more efficient then
old methods for thread cancellation.  And C++ unwinding needs the info in any
case and if exceptions need to be thrown throughasm code the ISVs hopefully will
use the cfi instructions and symbolic register names.

Version-Release number of selected component (if applicable):
2.15.92.0.2-13

How reproducible:
always

Steps to Reproduce:
1.use .cfi_register(rbx)
2.
3.
  
Actual results:
dwarf2 output shows rdx used

Expected results:
rbx in dwarf2 info

Additional info:
This bug has the potential to cause long standing problems in ISV applications
if the ISV starts using cfi instructions.  The patch is harmless and tested in FC4.

Comment 1 Jakub Jelinek 2005-07-06 09:57:59 UTC

The patch is http://sources.redhat.com/ml/binutils/2005-05/msg00243.html
The incorrectly numbered registers are rdx (ought to be 1, but gas emits 3),
rbx (should be 3 instead of 1), rsi (should be 4 instead of 5) and rdi (should be
5 instead of 4).

In glibc sources this problem occurs in 4 places:
./sysdeps/unix/sysv/linux/x86_64/setcontext.S:  cfi_def_cfa(%rdi, 0)
./sysdeps/unix/sysv/linux/x86_64/setcontext.S:  cfi_offset(%rbx,oRBX)
./sysdeps/x86_64/__longjmp.S:   cfi_def_cfa(%rdi, 0)
./sysdeps/x86_64/__longjmp.S:   cfi_offset(%rbx,JB_RBX*8)

Comment 5 Red Hat Bugzilla 2005-10-05 12:44:47 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2005-673.html