Red Hat Bugzilla – Bug 162545
wrong dwarf register numbers generated
Last modified: 2007-11-30 17:07:19 EST
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):
Steps to Reproduce:
dwarf2 output shows rdx used
rbx in dwarf2 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.
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/x86_64/__longjmp.S: cfi_def_cfa(%rdi, 0)
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.