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From: "wcohen at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: systemtap@sourceware.org
Subject: [Bug runtime/19360] New: Verify that examples and tapsets with return probes  use @entry for function arguments
Date: Fri, 11 Dec 2015 22:34:00 -0000
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X-Bugzilla-Component: runtime
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X-Bugzilla-Who: wcohen at redhat dot com
X-Bugzilla-Status: NEW
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https://sourceware.org/bugzilla/show_bug.cgi?id=3D19360

            Bug ID: 19360
           Summary: Verify that examples and tapsets with return probes
                    use @entry for function arguments
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: runtime
          Assignee: systemtap at sourceware dot org
          Reporter: wcohen at redhat dot com
  Target Milestone: ---

When reviewing test results on aarch64 I found that the systemtap lwtools
examples fslatency-nd.stp and fsslower-nd.stp were not using correct values=
 of
arguments for return probe.  This is because the aarch64 arguments are stor=
ed
in registers that can be overwritten in the function.  These uses should be
wrapped by @entry to make sure the value from the function entry is used.  =
It
would be very wise to review the other scripts and tapsets in systemtap to
ensure that this problem is not lurking elsewhere. For problem entries do
something like what is done in:

https://sourceware.org/git/gitweb.cgi?p=3Dsystemtap.git;a=3Dcommit;h=3D3d0c=
2f452f09a64b800aabe68508f8f0183f0ea1

--=20
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