Bug 671004 - user-space probes wrongly reject repnz;ret instructions
user-space probes wrongly reject repnz;ret instructions
Status: CLOSED ERRATA
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: systemtap (Show other bugs)
6.1
x86_64 Unspecified
low Severity medium
: rc
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Assigned To: Frank Ch. Eigler
qe-baseos-tools
:
Depends On:
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Reported: 2011-01-19 16:44 EST by Frank Ch. Eigler
Modified: 2011-05-19 09:54 EDT (History)
2 users (show)

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Fixed In Version: systemtap-1.4-2.el6
Doc Type: Bug Fix
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Last Closed: 2011-05-19 09:54:50 EDT
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RHEL 7.3 requirements from Atomic Host:


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Description Frank Ch. Eigler 2011-01-19 16:44:30 EST
GCC sometimes emits the code sequence "repnz;ret" to end a function.
systemtap's uprobes module rejects that as an unknown instruction
sequence, but this is unnecessary.  We have a patch in hand to let
such instructions be treated just like "rep;ret" = "ret".  This
should let stap run even with such optimized gcc code, without
risk.

commit 9ee518c4d6c36770aa5da534ae85754962bfe305
Author: Roland McGrath <roland@redhat.com>
Date:   Wed Jan 19 11:23:43 2011 -0800

    PR12419: fix x86 uprobes decoding of "repnz ret"
Comment 3 errata-xmlrpc 2011-05-19 09:54:50 EDT
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 therefore 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/RHBA-2011-0651.html

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