IV38752: ILLEGAL INSTRUCTION IN JIT-COMPILED CODE

APAR status

• Closed as program error.

Error description

• Error Message: A SIGILL or ABEND is raised by a JIT-compiled
  method that is attempting to execute z196 instructions such as
  Load High (LFH) or Rotate Then Inserted Selected Bits (RISBGN).
  This only occurs on a system that is equipped with an older
  processor such as the z9 or the z10, but is running z/VM to
  emulate newer hardware.
  .
  Stack Trace: N/A
  .
  

Local fix

• The issue can be avoided by configuring z/VM correctly to
  reflect the true capabilities of the underlying hardware.
  

Problem summary

• The problem is caused by the deceptive configuration of z/VM,
  which makes the operating system report the type of the
  processor as a z196 (or newer). The Java JIT compiler uses the
  return value of a system call to determine the processor type,
  and generate instructions to exploit features on that processor
  type. The resulting instructions are not actually executable on
  the underlying hardware, and cause a hardware trap.
  

Problem conclusion

• This defect will be fixed in:
  6.0.1 SR6
  7.0.0 SR5
  6.0.0 SR14
  .
  The JIT compiler has been updated to query the hardware directly
  about available features, instead of relying on the operating
  system.
  

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

  JIT

• Fixed component ID

  620700124

Applicable component levels

• R260 PSY

     UP

• R600 PSY

     UP