IJ10871: DATA EXCEPTION THROWN BY VCVBG INSTRUCTION

APAR status

• Closed as program error.

Error description

• Error Message: A VCVBG instruction throws a data exception (0C7
  abend on z/OS - SIGFPE on Linux on Z).
  .
  Stack Trace: The problematic instructions come from usage of the
  Data Access Accelerator (DAA) API, specifically
  com/ibm/dataaccess/DecimalData.convertPackedDecimalToLong_(<OSB>
  BIIZ)J
  .
  This problem can only happen on IBM Z on z14 or later systems.
  The problem is introduced in Java 8 SR5.
  

Local fix

• -Xjit:disableIntrinsics
  Note: this will turn off DAA optimizations decreasing
  performance of the DAA API.
  

Problem summary

• An off-by-one error is made in the JIT compiled instructions
  associated with
  com/ibm/dataaccess/DecimalData.convertPackedDecimalToLong_(<OSB>
  BIIZ)J
  A vector load instruction VLRLR loads one more least significant
  byte than it should which means the data is invalid and likely
  contains an invalid sign bit in BCD format. When the subsequent
  VCVBG instruction tries to operate on the data it throws a data
  exception as a result of the invalid sign bit.
  

Problem conclusion

• This problem has been fixed by
  https://github.com/eclipse/openj9/pull/29
  .
  This APAR will be fixed in the following Java Releases:
   8 SR5 FP10 (8.0.5.10)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
   https://www.ibm.com/developerworks/java/jdk/
  

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:

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels