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Bug 152440 - ppc64 arches can crash when single setpping a debugger through syscall return code
ppc64 arches can crash when single setpping a debugger through syscall return...
Status: CLOSED ERRATA
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: kernel (Show other bugs)
4.0
powerpc Linux
medium Severity medium
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Assigned To: Neil Horman
Brian Brock
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Depends On:
Blocks: 154907 156322
  Show dependency treegraph
 
Reported: 2005-03-29 10:25 EST by Neil Horman
Modified: 2007-11-30 17:07 EST (History)
4 users (show)

See Also:
Fixed In Version: RHSA-2005-514
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Environment:
Last Closed: 2005-10-05 08:55:12 EDT
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RHEL 7.3 requirements from Atomic Host:
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Attachments (Terms of Use)
patch to swap stack restore/RI clear ordering (479 bytes, patch)
2005-03-29 10:25 EST, Neil Horman
no flags Details | Diff

  None (edit)
Description Neil Horman 2005-03-29 10:25:58 EST
Description of problem:
ppc64 arches can crash when single setpping a debugger through syscall return
code.  Currently the ppc64 user stack is restored before clearing the RI bit in
the MSR.  Before the RI bit is cleared, traps are allowed, and if one is taken
after the stack is resored, but before the RI bit is cleared, unpredictable and
fatal results (oopses) can occur.

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

How reproducible:
always

Steps to Reproduce:
1. Use a hardware/jtag debugger to write software interrupt instructions
(software breakpoints), to the code addresses between the instructions in
entry.S where the user stack is restored and the RI bit is cleared in the
syscall_exit code.

2. execute a syscall in user space.
  
Actual results:
System will crash

Expected results:
Breakpoint is handled, system does not crash

Additional info:
Comment 1 Neil Horman 2005-03-29 10:25:59 EST
Created attachment 112418 [details]
patch to swap stack restore/RI clear ordering
Comment 2 Neil Horman 2005-03-29 10:26:53 EST
attached patch has been accepted on rhkernel-list for RHEL4-U2.
Comment 6 Red Hat Bugzilla 2005-10-05 08:55:12 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 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-2005-514.html

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