8336768: Allow captureCallState and critical linker options to be combined #22327

JornVernee · 2024-11-22T14:31:23Z

Allow captureCallState and critical(true) linker options to be combined. This allows passing a Java array to capture call state.

One caveat is that the linker expects the memory to be aligned, which means that at least an int[] has to be used (i.e. byte[] will no work).

This patch contains two implementations: one for the linkers that use CallingSequenceBuilder. That one is quite straight-forward, as we can just mimic what we already do for other memory segment arguments, but also for the capture state segment. i.e. split it into base and offset, and pass that down to our downcall stub. The stub will then add the offset and oop together, and pass use the resulting address to write to.

The other implementation is for the fallback linker. This handles the capture state a little differently, but essentially currently just passes the native address to the back end for the native code to write the captured state into. I've just added another heap base parameter for that capture state segment to the back end, which is then turned into a native address using JNI's GetPrimitiveArrayCritical, similarly to what we do for other heap segments.

Testing: jdk_foreign test suite.

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Issues

JDK-8336768: Allow captureCallState and critical linker options to be combined (Enhancement - P3)
JDK-8345106: Allow captureCallState and critical linker options to be combined (CSR)

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Maurizio Cimadamore (@mcimadamore - Reviewer)

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bridgekeeper · 2024-11-22T14:32:30Z

👋 Welcome back jvernee! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2024-11-22T14:33:02Z

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

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

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

8336768: Allow captureCallState and critical linker options to be combined

Reviewed-by: mcimadamore

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At the time when this comment was updated there had been 168 new commits pushed to the master branch:

68b1b94: 8344904: Interned strings in old classes are not stored in CDS archive
1997e89: 8345346: Shenandoah: Description of ShenandoahGCMode still refers to incremental update mode
3a3bcd5: 8344800: Add W3C DTDs and XSDs to the JDK built-in Catalog
940aa7c: 8344397: Remove Security Manager dependencies from java.security and sun.security packages
3d0d0e6: 8345012: os::build_agent_function_name potentially wastes a byte when allocating the buffer
525f33b: 8345324: Update comment in SourceVersion for language evolution history for changes in 24
d6a5f1b: 8344768: Consider removing "sun.security.krb5.autodeducerealm" system property
7c944ee: 8345172: x86: Some CPU feature asserts are declared as 32-bit only
67f18cc: 8345142: Remove uses of SecurityManager in Printing related classes
352201d: 8343788: Provide means to alter lib/tzmappings entries on Windows
... and 158 more: https://git.openjdk.org/jdk/compare/82c3612d775840aa4b851a29b8ee3337950d5aeb...master

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openjdk · 2024-11-22T14:33:38Z

@JornVernee The following label will be automatically applied to this pull request:

core-libs

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

JornVernee · 2024-11-27T11:12:53Z

src/java.base/share/classes/jdk/internal/foreign/abi/fallback/FallbackLinker.java

            if (invData.capturedStateMask() != 0) {
                capturedState = SharedUtils.checkCaptureSegment((MemorySegment) args[argStart++]);
+                if (!invData.allowsHeapAccess) {
+                    SharedUtils.checkNative(capturedState);


I noticed that this check was missing in the fallback linker, and we were actually crashing when a heap segment was passed as the capture state segment. I've added a new test case that checks that this works as well.

JornVernee · 2024-11-27T11:27:03Z

/csr

openjdk · 2024-11-27T11:27:27Z

@JornVernee has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@JornVernee please create a CSR request for issue JDK-8336768 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.

mlbridge · 2024-11-27T11:30:52Z

Webrevs

01: Full - Incremental (2b332c33)
00: Full (f42f9515)

mcimadamore · 2024-11-27T19:21:30Z

src/java.base/share/classes/jdk/internal/foreign/abi/NativeEntryPoint.java

        if (methodType.parameterType(0) != long.class) {
            throw new AssertionError("Address expected as first param: " + methodType);
        }
        int checkIdx = 1;
        if ((needsReturnBuffer && methodType.parameterType(checkIdx++) != long.class)
-            || (savedValueMask != 0 && methodType.parameterType(checkIdx) != long.class)) {
+            || (savedValueMask != 0 &&


Maybe this routine is getting too complex and it would be better to split the checks (and add some comments) ? E.g. we need to check that if there's a return buffer, a certain low-level argument is long and, if there's need to capture state, we either have long, or an Object,long pair.

Perhaps, even throwing different assertion error might help

Yeah... I'll split this up a bit to make it more readable.

minborg · 2024-11-28T07:52:56Z

src/java.base/share/classes/jdk/internal/foreign/abi/CallingSequence.java

@@ -195,6 +195,10 @@ public boolean needsTransition() {
        return !linkerOptions.isCritical();
    }

+    public boolean usingAddressPairs() {


Nit: Copyright years

mcimadamore · 2024-11-28T12:06:13Z

src/java.base/share/classes/jdk/internal/foreign/abi/fallback/LibFallback.java

@@ -90,10 +90,11 @@ private static boolean tryLoadLibrary() {
     * @see jdk.internal.foreign.abi.CapturableState
     */
    static void doDowncall(MemorySegment cif, MemorySegment target, MemorySegment retPtr, MemorySegment argPtrs,
-                           MemorySegment capturedState, int capturedStateMask,
+                           Object captureStateHeapBase, MemorySegment capturedState, int capturedStateMask,


I find it a bit weird that this method is receiving both the captured segment base and the segment itself. It almost seems as if the checks we do in FallbackLinker should be done here?

I see what you mean, and I agree it looks a bit strange. but we also pass the array of heap bases separately here (which is more or less a forced move due to how the libffi API works). So, I think the current code is more inline with that. The LibFallback class is only supposed to be a thin wrapper around the native methods in fallbackLinker.c. The actual logic is all in FallbackLinker.

mcimadamore

Looks good - left some minor comments

JornVernee · 2024-12-03T12:27:37Z

/integrate

openjdk · 2024-12-03T12:28:22Z

Going to push as commit 8cad043.
Since your change was applied there have been 185 commits pushed to the master branch:

63af2f4: 8344414: ZGC: Another division by zero in rule_major_allocation_rate
077b842: 8345074: java.net.InterfaceAddress constructor could be made private
ec93cc5: 8343932: Error when parsing qualified generic type test pattern in switch
c330b90: 8343780: Add since checker tests to the Tools area modules and add missing @SInCE to jdk.jfr
8dada73: 8345120: A likely bug in StringSupport::chunkedStrlenShort
659f70b: 8343418: Unnecessary Hashtable usage in CSS.htmlAttrToCssAttrMap
5c8cb2e: 8337199: Add jcmd Thread.vthread_scheduler and Thread.vthread_pollers diagnostic commands
3eb5461: 8343791: Socket.connect API should document whether the socket will be closed when hostname resolution fails or another error occurs
4ac2e47: 8343800: Cleanup definition of NULL_WORD
a3b58ee: 8339983: [s390x] secondary_super_cache does not scale well: C1 and interpreter
... and 175 more: https://git.openjdk.org/jdk/compare/82c3612d775840aa4b851a29b8ee3337950d5aeb...master

Your commit was automatically rebased without conflicts.

openjdk · 2024-12-03T12:28:32Z

@JornVernee Pushed as commit 8cad043.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

dmlloyd · 2024-12-03T13:16:11Z

I've already tested this and it works great. Thanks!

Allow combining captureCallState and critical(true)

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openjdk bot added the core-libs core-libs-dev@openjdk.org label Nov 22, 2024

fallback impl

c119bac

JornVernee commented Nov 27, 2024

View reviewed changes

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JornVernee marked this pull request as ready for review November 27, 2024 11:26

openjdk bot added rfr Pull request is ready for review csr Pull request needs approved CSR before integration labels Nov 27, 2024

Add test for capture state alignment

8e5a753

mcimadamore reviewed Nov 27, 2024

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minborg reviewed Nov 28, 2024

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mcimadamore approved these changes Nov 28, 2024

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review comments

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mcimadamore approved these changes Nov 29, 2024

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openjdk bot added ready Pull request is ready to be integrated and removed csr Pull request needs approved CSR before integration labels Dec 2, 2024

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openjdk bot closed this Dec 3, 2024

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Dec 3, 2024

JornVernee deleted the Critical+Capture branch December 3, 2024 12:32

JornVernee mentioned this pull request Dec 3, 2024

8345389: Bump missed copyright years for JDK-8336768 #22513

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fangerer mentioned this pull request Dec 13, 2024

[GR-60395] Allow combination of captureCallState and critical(true). oracle/graal#10301

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8336768: Allow captureCallState and critical linker options to be combined #22327

8336768: Allow captureCallState and critical linker options to be combined #22327

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dmlloyd commented Dec 3, 2024

8336768: Allow captureCallState and critical linker options to be combined #22327

8336768: Allow captureCallState and critical linker options to be combined #22327

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