PJ40865: OPR-4 IN DATA COLLECTION

APAR status

• Closed as program error.

Error description

• See Problem Summary.
  

Local fix

• The fix in chsz.cpy:
     1741          ICSTK REG=R8 ZTPF11
     1742          LG    R8,CE2TOES(,R9)     Address of top of the
  stack (EVA)    ZTPF11
     1743          AGHI  R8,-ICST_LEN        Allocate minimum
  stack frame         ZTPF11
     1744          AGHI  R9,X'1000'          Address page 3 of the
  ECB            ZTPF11
     1745          STG   R8,CE3STK2C(,R9)    Store stack address
  (EVA)            ZTPF11
     1747          ST    R8,CE3CMSTK(,R9)
  

Problem summary

• APAR NUMBER:  PJ40865
  PRODUCT:  z/TPF
  FUNCTIONAL AREA:  DATA COLLECTION
  SHIPPED IN PUT:  10
  
  ABSTRACT:
  An OPR-4 or CTL-1 dump from CCDCOL may occur while running data
  collection.
  
  PACKAGE CONTENTS:
  Source Segments:
  (C) base/cp/chsz.cpy
  
  Object Only Binaries:
  None.
  
  Configuration Independent Binaries:
  None.
  
  Support Files:
  None.
  
  OTHER BINARIES TO BUILD: YES
  (C) <sys>/obj/ccnucl.o
  (C) <sys>/load/CPS0.so
  
  COMMENTS:
  When data collection is running, the low core hooks in CCHOOK
  are used to record program enters and backs. The CHK3_DACOL_EXT
  hook is used to record a C language function return. The
  CHK3_DACOL_EXT hook compares the stack frame to the cross
  module stack frame pointer (CE3CMSTK) to determine whether the
  function return is returning to a function within the same load
  module or to an external load module. If the stack frame is
  equal to CE3CMSTK, data collection assumes that this is a
  return to an external load module and this function return is
  recorded. If the function return is recorded, the PAT slot of
  the shared object that is being returned to is obtained from
  field ICST_PAT in the cross module stack frame.
  
  The problem is that cross module stack frame pointer (CE3CMSTK)
  is not initialized when an ECB is created. CE3CMSTK is set on
  the first call to a C program. However, certain libraries such
  as CTAL have a special linkage that does not set CE3CMSTK. If
  the ECB enters an assembler program and this assembler program
  does a CALLC to a function in CTAL, CE3CMSTK will not be set.
  In this case CE3CMSTK has garbage in it. If CTAL does a call to
  another function within CTAL, the PAT address is not saved in
  ICST_PAT. On return from the second function within CTAL, if
  the current stack frame is equal to the contents in CE3CMSTK,
  CHK3_DACOL_EXT will assume that this is a function return to an
  external load module. It will load the PAT address into R7 from
  ICST_PAT, which is not initialized. At this point, R7 has
  garbage in it. As a result, when CCDCOL attempts to use the PAT
  pointed to by R7 an OPR-4 or CTL-1 dump may occur. This OPR-4
  or CTL-1 dump may be accompanied by a CTL-572 dump.
  

Problem conclusion

• SOLUTION:
  The cross module stack frame pointer (CE3CMSTK) is initialized
  when an ECB is created.
  
  COREQS: NO
  None.
  
  MIGRATION CONSIDERATIONS: NO
  None.
  
  BUILD COMMANDS AND INSTRUCTIONS: YES
  #maketpf commands for linux
  maketpf -f CPS0 ccnucl.o
  maketpf CPS0 link
  
  UPDATED INFORMATION UNITS: NO
  None.
  
  See your IBM representative if you need additional information.
  
  DOWNLOAD INSTRUCTIONS:
  http://www.ibm.com/software/htp/tpf/maint/maintztpf.html
  
  APAR URL:
  http://www.ibm.com/software/htp/tpf/ztpfmaint/put10/PJ40865.htm
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  Z/TPF

• Fixed component ID

  5748T1501

Applicable component levels

• R110 PSY

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