IZ64807: JAVA JIT COMPILER CRASH ON IA32 IN USESREGISTER

APAR status

• Closed as program error.

Error description

• Error Message: A SIGSEGV/GPF is raised in the JIT compiler
  module while a method is being compiled. The crashing function
  is TR_IA32VirtualGuardNOPInstruction::usesRegister(). The
  problem only occurs rarely on IA32. The problem may occur with
  both Java 5 and Java 6.
  .
  Stack Trace:
  j9jit23!TR_IA32VirtualGuardNOPInstruction::usesRegister+0x1d
  j9jit23!TR_X86CodeGenerator::pickNOPRegister+0x69
  j9jit23!TR_X86CodeGenerator::generatePadding+0x4e
  j9jit23!TR_IA32BoundaryAvoidanceInstruction::generateBinaryEncod
  ing+0xc9
  j9jit23!TR_Instruction::generateBinaryEncoding+0xe
  j9jit23!TR_X86CodeGenerator::doCodeGeneration+0x28e
  j9jit23!TR_CodeGenerator::generateCode+0x4b4
  j9jit23!TR_Compilation::compile+0x22a
  j9jit23!TR_CompilationInfo::compile+0x2ed
  j9jit23!TR_CompilationInfo::wrappedCompile+0x3c6
  J9PRT23!j9sig_protect+0x41
  j9jit23!TR_CompilationInfo::compile+0x111
  j9jit23!protectedCompilationThreadProc+0x1cf
  J9PRT23!j9sig_protect+0x41
  j9jit23!compilationThreadProc+0xa5
  J9THR23!thread_wrapper+0xbf
  .
  

Local fix

• This issue can be avoided using the
  -Xjit:disableVirtualGuardNOPing option. Note that this option
  can incur a performance impact of approximately 4% to 10% (in
  the worst case), depending on the nature of the Java
  application.
  

Problem summary

• The problem is caused by a defect in the JIT compiler which
  leaves a certain data field uninitialized. The value of the
  field is later used in the computation of a memory address. The
  incorrect memory address then causes a crash when it is
  accessed.
  

Problem conclusion

• This defect will be fixed in:
  5.0.0 SR12
  6.0.0 SR8
  .
  The JIT compiler has been updated to initialize the data field
  properly.
  .
  To obtain the fix:
  Install build 20091127 or later
  

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:

  IZ64833

Fix information

• Fixed component name

  JAVA 5 JIT

• Fixed component ID

  620500124

Applicable component levels

• R500 PSN

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