8264358: Don't create invalid oop in method handle tracing

[stefank]

The mh field in:

struct MethodHandleStubArguments {
  const char* adaptername;
  oopDesc* mh;
  intptr_t* saved_regs;
  intptr_t* entry_sp;
};

doesn't always point to a valid object. The oopDesc* is then implicitly converted to an oop here:

void trace_method_handle_stub_wrapper(MethodHandleStubArguments* args) {
  trace_method_handle_stub(args->adaptername,
                           args->mh,
                           args->saved_regs,
                           args->entry_sp);
}

This gets caught by my ad-hoc verification code that verifies oops when they are created/used.

I propose that we don't create an oop until it mh is actually used, and it has been checked that the argument should contain a valid oop. I started with a more elaborate fix that changed the type of mh to be void*, but then reverted to a more targetted fix to remove the early oopDesc* > oop conversion.

One thing that I am curious about is this code inside trace_method_handle_stub:

if (has_mh && oopDesc::is_oop(mh)) {
  mh->print_on(&ls);

Delaying the oopDesc* > oop conversion to after the has_mh check solves my verification failure, but I wonder if the oopDesc::is_oop(mh) call is really needed when we have the has_mh check?

---

Progress

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Issue

• JDK-8264358: Don't create invalid oop in method handle tracing

Reviewers

• Nils Eliasson (@neliasso - Reviewer)

Reviewing

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[mlbridge]

Webrevs

• 00: Full (00c9e57)

[stefank]

Could I get a review for this? It is a super small change.

[neliasso]

Looks good.

[openjdk]

@stefank This change now passes all automated pre-integration checks.

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After integration, the commit message for the final commit will be:

8264358: Don't create invalid oop in method handle tracing

Reviewed-by: neliasso

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At the time when this comment was updated there had been 157 new commits pushed to the master branch:

• b3782ea: 8264918: [JVMCI] getVtableIndexForInterfaceMethod doesn't check that type and method are related
• f7a6c63: 8259822: [PPC64] Support the prefixed instruction format added in POWER10
• a45733f: 8264779: Fix doclint warnings in java/nio
• 3e57924: 8264885: Fix the code style of macro in aarch64_neon_ad.m4
• 051c117: 8264923: PNGImageWriter.write_zTXt throws Exception with a typo
• 1c6b113: 8264513: Cleanup CardTableBarrierSetC2::post_barrier
• 666fd62: 8264881: Remove the old development option MemProfiling
• 951f277: 8264874: Build interim-langtools for HotSpot only if Graal is enabled
• 719f95e: 8260693: Provide the support for specifying a signer in keytool -genkeypair
• 77b1673: 8256245: AArch64: Implement Base64 decoding intrinsic
• ... and 147 more: https://git.openjdk.java.net/jdk/compare/aefc1560b51f0ce96d8f5ce396ba0d2fe08fd650...master

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[stefank]

Thanks, @neliasso.
/integrate

[TobiHartmann]

Looks good to me too.

[openjdk]

@stefank Since your change was applied there have been 173 commits pushed to the master branch:

• 627ad9f: 8262328: Templatize JVMFlag boilerplate access methods
• c15680e: 8264868: Reduce inclusion of registerMap.hpp and register.hpp
• 5784f6b: 8264948: Check for TLS extensions total length
• 42f4d70: 8264649: runtime/InternalApi/ThreadCpuTimesDeadlock.java crash in fastdebug C2 with -XX:-UseTLAB
• 76bd313: 8264872: Dependencies: Migrate to PerfData counters
• 07c8ff4: 8264871: Dependencies: Miscellaneous cleanups in dependencies.cpp
• 863feab: 8005295: Use mandated information for printing of repeating annotations
• f26cd2a: 8264997: Remove SystemDictionary::cache_get
• 9ebc497: 8264765: BreakIterator sees bogus sentence boundary in parenthesized “i.e.” phrase
• ec31b3a: 8264727: Shenandoah: Remove extraneous whitespace from phase timings report
• ... and 163 more: https://git.openjdk.java.net/jdk/compare/aefc1560b51f0ce96d8f5ce396ba0d2fe08fd650...master

Your commit was automatically rebased without conflicts.

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[stefank]

Thanks, @TobiHartmann