IJ56399: JAVA JIT: CRASH IN REPLACETRAMPOLINE() ON JAVA 11+

APAR status

• Closed as program error.

Error description

• Error Message: SIG_SEGV in the JIT runtime method
  replaceTrampoline().
  .
  Stack Trace: libj9jit29.so:
  _ZN3OMR9CodeCache17replaceTrampolineEP20TR_OpaqueMethodBlockPvS3
  _S3_b
  libj9jit29.so:
  _ZN3OMR16CodeCacheManager17replaceTrampolineEP20TR_OpaqueMethodB
  lockPvS3_S3_S3_b
  libj9jit29.so: mcc_replaceTrampoline
  libj9jit29.so: _Z15ppcCodePatchingPvS_S_S_S_S_
  libj9jit29.so:
  _ZN3OMR9CodeCache14patchCallPointEP20TR_OpaqueMethodBlockPvS3_S3
  _
  libj9jit29.so: mcc_callPointPatching_unwrapper
  libj9jit29.so: old_slow_jitCallCFunction
  .
  The issue can only occur on Java 11 or higher and only on POWER
  hardware. The problem is timing sensitive so the issue will be
  intermittent. Other platforms alike Z or x86 are not effects by
  this issue since the problem existed in POWER specific code.
  

Local fix

• The chances of hitting this issue can be greatly reduced by
  using the following java command line parameter, but please
  note, this option will have a significant effect on performance:
  -Xjit:inhibitRecompilation
  

Problem summary

• Starting with Java11 (due to JEP 181) the javac compiler can use
  the "invokevirtual" bytecode to invoke private methods. The way
  the POWER code generator handled this situation allowed for a
  small timing window where it would think it could patch the call
  site, which is not possible under this scenario. The attempt to
  patch would result in a crash because the required runtime data
  does not exist to support the patching procedure.
  

Problem conclusion

• The JIT was modified so that it would detect this situation and
  abort the patching attempt.
  https://github.com/eclipse-openj9/openj9/pull/22714
  .
  This APAR will be fixed in the following Releases:
  .
  IBM Semeru Runtimes
   21 21.0.10.0
   21 21.0.10.0
   17 17.0.18.0
   11 11.0.30.0
  .
  Downloads and supplementary documentation can be found at the
  following locations:
  - For non z/OS operating systems:
   - IBM Semeru Runtimes, Version 11 and later
   https://www.ibm.com/semeru-runtimes/downloads/
   - IBM SDK, Java Technology Edition, Version 8
   https://www.ibm.com/support/pages/java-sdk-downloads/
  - For the z/OS operating system:
   - Java SDK Products on z/OS
   https://www.ibm.com/support/pages/java-sdk-products-zos
  

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