IZ87520: JAVA6 JIT: SIGTRAP ON POWER OR SIGSEGV ON X86 WHILE USING -XRS AND -XSHARECLASSES

APAR status

• Closed as program error.

Error description

• The Java process crashes with a core dump reporting a SIGTRAP
  when running on PowerPC or a SIGSEGV on x86.
  
  The problem can only occur on PowerPC and x86 machines
  (Intel/AMD). The problem will only occur when the JIT loads
  compiled code from the shared class cache (-Xshareclasses) where
  the JVM that generated the cached code is not using the -Xrs
  option and the JVM loading the cached code is using the -Xrs
  option.
  

Local fix

• To avoid this problem you must clear the shared class cache
  using -Xshareclasses:destroy before you add or remove the -Xrs
  option. You also need to be sure that all JVM's using the same
  shared class cache are consistent in regards to the use of the
  -Xrs option.
  

Problem summary

• Compiled code added to the shared class cache by a JVM not using
  the -Xrs option is loaded and executed by a JVM that is using
  the -Xrs option. This results in the "-Xrs" JVM executing code
  that uses TRAP instructions (PPC) or SIGSEGV signals (x86) to
  handle some types of Java exceptions. When using the -Xrs option
  the JVM does not install SIGTRAP or SIGSEGV signal handlers and
  therefore Java exceptions handled in this manner will result in
  a crash.
  

Problem conclusion

• The JVM has been changed to store information about the -Xrs
  switch in the share class cache, and will not use compiled code
  from the shared class cache if the -Xrs usage does not match.
  

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

• R600 PSY

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