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  1. JDK
  2. JDK-8158318

JVM on PPC64 LE crashes due to an illegal instruction in JITed code

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P4
    • Resolution: Duplicate
    • Affects Version/s: 8u91, 9
    • Fix Version/s: None
    • Component/s: hotspot
    • Labels:
      None
    • Subcomponent:
    • CPU:
      ppc
    • OS:
      linux

      Description

      [from http://mail.openjdk.java.net/pipermail/ppc-aix-port-dev/2016-May/002534.html]

      The following test case has been isolated by Hiroshi Horii and generates
      the illegal instruction, crashing the JVM on PPC64 LE:

      UnalignedUnsafeAccess.java:
      http://hastebin.com/raw/uqegukific

      $ javac UnalignedUnsafeAccess.java
      $ java -Xcomp -Xbatch UnalignedUnsafeAccess

      The issue can be reproduced on OpenJDK 8 downstream, OpenJDK 8, and
      OpenJDK 9 - hs_err logs:

      OpenJDK 9, tag 0be6f4f5d186 jdk-9+120:
      http://hastebin.com/raw/ecuhukutur

      OpenJDK 8, tag 5aaa43d91c73 tip:
      http://hastebin.com/raw/ipohoyafos

      OpenJDK 8 downstream:

      Ubuntu 16.04 LTS
      build 1.8.0_91-8u91-b14-0ubuntu4~16.04.1-b14
      http://hastebin.com/raw/yetizebofo

      RHEL 7.2:
      build 1.8.0_91-b14
      http://hastebin.com/raw/irequfawaw

      The crash happens when an illegal instruction - 0xea2f0013 - is executed.

      The backtrace shows:

      Stack: [0x00003fff56030000,0x00003fff56430000], sp=0x00003fff5642b8d0, free space=4078k
      Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
      V [libjvm.so+0x162104] loadI2LNode::emit(CodeBuffer&, PhaseRegAlloc*) const+0x194
      V [libjvm.so+0x8ece28] Compile::fill_buffer(CodeBuffer*, unsigned int*)+0x4e8
      V [libjvm.so+0x368e08] Compile::Code_Gen()+0x3c8
      V [libjvm.so+0x369e04] Compile::Compile(ciEnv*, C2Compiler*, ciMethod*, int, bool, bool, bool)+0xf64
      V [libjvm.so+0x271380] C2Compiler::compile_method(ciEnv*, ciMethod*, int)+0x1f0
      V [libjvm.so+0x3785a4] CompileBroker::invoke_compiler_on_method(CompileTask*)+0xd54
      V [libjvm.so+0x379dc8] CompileBroker::compiler_thread_loop()+0x488
      V [libjvm.so+0xa5de90] compiler_thread_entry(JavaThread*, Thread*)+0x20
      V [libjvm.so+0xa690c8] JavaThread::thread_main_inner()+0x178
      V [libjvm.so+0x8c8c10] java_start(Thread*)+0x170
      C [libpthread.so.0+0x833c] start_thread+0xfc
      C [libc.so.6+0x12b014] clone+0xe4

      loadI2LNode class is generated according to the following ADL code in
      ppc.ad file:

      instruct loadI2L(iRegLdst dst, memory mem) %{
        match(Set dst (ConvI2L (LoadI mem)));
        predicate(_kids[0]->_leaf->as_Load()->is_unordered());
        ins_cost(MEMORY_REF_COST);

        format %{ "LWA $dst, $mem \t// loadI2L" %}
        size(4);
        ins_encode %{
          // TODO: PPC port $archOpcode(ppc64Opcode_lwa);
          int Idisp = $mem$$disp + frame_slots_bias($mem$$base, ra_);
          __ lwa($dst$$Register, Idisp, $mem$$base$$Register);
        %}
        ins_pipe(pipe_class_memory);
      %}

      So the generated illegal instruction comes from:
      lwa 17,17,15 (DS-form: lwa RT, DS, RA)

      As DS field must always be 4-byte aligned (i.e. DS field is always
      concatenated with 0b00), 17 as DS (middle 17 value) is illegal,
      generating the illegal instruction in question:

      11101010000000000000000000000010: LWA
      00000010001000000000000000000000: 17
      00000000000000000000000000010001: 17
      00000000000011110000000000000000: 15
      --------------------------------
      11101010001011110000000000010011: 0xEA2F0013 => Illegal instruction

      The following change is proposed to fix the issue and deals with the
      unaligned displacements:

      OpenJDK 9 webrev:
      81.de.7a9f.ip4.static.sl-reverse.com./illegal/9

      OpenJDK 8 webrev:
      81.de.7a9f.ip4.static.sl-reverse.com./illegal/8

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              • Assignee:
                Unassigned
                Reporter:
                andrew Andrew Hughes
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                Dates

                • Created:
                  Updated:
                  Resolved: