8349374: [JVMCI] concurrent use of HotSpotSpeculationLog can crash

[tkrodriguez]

This ensures that collectFailedSpeculations sees the initialization of the recently allocated failedSpeculationsAddress memory.

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Issue

• JDK-8349374: [JVMCI] concurrent use of HotSpotSpeculationLog can crash (Bug - P4)

Reviewers

• Doug Simon (@dougxc - Reviewer) Review applies to aefc1dfd
• Vladimir Kozlov (@vnkozlov - Reviewer)

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[openjdk]

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

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8349374: [JVMCI] concurrent use of HotSpotSpeculationLog can crash

Reviewed-by: kvn, dnsimon

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At the time when this comment was updated there had been 17 new commits pushed to the master branch:

• 379c3f9: 8347836: Disabled PopupMenu shows shortcuts on Mac
• 82bc0a7: 8344316: security/auth/callback/TextCallbackHandler/Password.java make runnable with JTReg and add the UI
• 2f2f7cf: 8349084: Update vectors used in several PQC benchmarks
• b9b62a0: 8346792: serviceability/jvmti/vthread/GetThreadState/GetThreadState.java testObjectWaitMillis failed
• 6b994cd: 8333697: C2: Hit MemLimit in PhaseCFG::global_code_motion
• 2ff8440: 8349344: Clarify documentation of Arena.ofConfined
• 19399d2: 8348572: C2 compilation asserts due to unexpected irreducible loop
• 6146588: 8348190: Framework for tracing makefile inclusion and parsing
• 66a3898: 8348659: AArch64: IR rule failure with compiler/loopopts/superword/TestSplitPacks.java
• 40603a5: 8349214: Improve size optimization flags for MSVC builds
• ... and 7 more: https://git.openjdk.org/jdk/compare/b985347c2383a7a637ffa9a4a8687f7f7cde1369...master

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• 01: Full - Incremental (459f5c36)
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[dougxc]

It's still possible for getFailedSpeculationsAddress() to return 0 (i.e. when managesFailedSpeculations is false). So I think this should be:

diff --git a/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotSpeculationLog.java b/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotSpeculationLog.java
index fd46e281c3b..a861c00d77d 100644
--- a/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotSpeculationLog.java
+++ b/src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotSpeculationLog.java
@@ -171,8 +171,9 @@ public String toString() {

     @Override
     public void collectFailedSpeculations() {
-        if (failedSpeculationsAddress != 0 && UnsafeAccess.UNSAFE.getLong(failedSpeculationsAddress) != 0) {
-            failedSpeculations = compilerToVM().getFailedSpeculations(failedSpeculationsAddress, failedSpeculations);
+        long address = getFailedSpeculationsAddress();
+        if (address != 0 && UnsafeAccess.UNSAFE.getLong(address) != 0) {
+            failedSpeculations = compilerToVM().getFailedSpeculations(address, failedSpeculations);
             assert failedSpeculations.getClass() == byte[][].class;
         }
     }

[tkrodriguez]

I'm filtering out 0 above this line and getFailedSpeculationsAddress() can't return 0 if failedSpeculationsAddress is already non-zero.

failedSpeculationsAddress also can't be 0 if managesFailedSpeculations is false since we throw IllegalArgumentException in that case.

[dougxc]

failedSpeculationsAddress also can't be 0 if managesFailedSpeculations is false since we throw IllegalArgumentException in that case.

Ok, I'd forgotten about that invariant. Might be worth reminding the reader of it with a comment in collectFailedSpeculations.

[tkrodriguez]

I've updated the javadoc for getFailedSpeculationsAddress to specify that it always returns non-zero. I also expanded the comments in collectFailedSpeculations and call getFailedSpeculationsAddress() to get the value. I think it's clearer what's going on now.

[vnkozlov]

Seems fine.

[tkrodriguez]

Thanks!

/integrate

[openjdk]

Going to push as commit 7f6c687.
Since your change was applied there have been 52 commits pushed to the master branch:

• bd9b24c: 8349512: Duplicate PermittedSubclasses entries with doclint enabled
• b40f8ee: 8337251: C1: Improve Class.isInstance intrinsic
• 88a8483: 8349121: SSLParameters.setApplicationProtocols() ALPN example could be clarified
• fb847bb: 8349493: Replace sun.util.locale.ParseStatus usage with java.text.ParsePosition
• 7cd5cb2: 8349532: Refactor ./util/Pem/encoding.sh to run in java
• 86cec4e: 8343782: G1: Use one G1CardSet instance for multiple old gen regions
• 006ed5c: 8349375: Cleanup AIX special file build settings
• 3989a19: 8344925: translet-name ignored when package-name is also set
• 1eb54e4: 8346049: jdk/test/lib/security/timestamp/TsaServer.java warnings
• a0c7f66: 8349508: runtime/cds/appcds/TestParallelGCWithCDS.java should not check for specific output
• ... and 42 more: https://git.openjdk.org/jdk/compare/b985347c2383a7a637ffa9a4a8687f7f7cde1369...master

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[openjdk]

@tkrodriguez Pushed as commit 7f6c687.

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