IJ53429: JAVA (9+) JIT: OPTIMIZATION OF STRINGLATIN1 CLASS CAUSES SEGV

APAR status

• Closed as program error.

Error description

• Error Message: A SIG_SEGV is received when running JIT compiled
  code that includes the StringLatin1.inflate() code.
  .
  Stack Trace: This stack trace is one example of the problem, but
  since the JIT can inline the StringLatin1.inflate() method while
  compiling other methods (as is the case here) the stack trace
  could look different for other instances of the problem.
  0x100113985f4 {java/lang/String.getChars} JIT
  0x100117050e8 {org/jboss/modules/PathUtils.canonicalize} JIT
  0x100241debd0 {org/jboss/modules/Module.getResources} INT
  0x1002417b5f5
  {org/jboss/modules/ModuleClassLoader.findResources} INT
  0x1002417edc1
  {org/jboss/modules/ConcurrentClassLoader.getResources} INT
  .
  This issue is only possible in Java9 or better since the
  StringLatin1 class does not exist in Java8. The issue is only
  possible when running on a POWER machine (IBMZ and X86 CPU can
  not encounter this particular issue).
  

Local fix

• The problem can be avoided by exporting the following
  environment variable before starting the JVM.
  TR_DisableStringInflateIntrinsic=1
  This option should have a minor effect on performance unless
  very large string processing is the dominate workload in your
  Java application.
  

Problem summary

• The JIT failed to issue a sign extend instruction before
  performing an address calculation using a 32bit offset. The
  possibility of garbage in the upper 32bits of the 64bit register
  containing the 32bit offset could lead to an incorrect address
  resulting in a SEGV.
  

Problem conclusion

• The JIT was modified so that a sign extend instruction is issued
  prior to performing the address calculation.
  https://github.com/eclipse-openj9/openj9/pull/20970
  .
  This APAR will be fixed in the following Releases:
  .
  IBM Semeru Runtimes
   21 21.0.7.0
   17 17.0.15.0
   11 11.0.27.0
  .
  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