8373110: jstack --mixed frames are broken on macOS after JDK-8371194 #28686

YaSuenag · 2025-12-06T02:35:03Z

JDK-8371194 (PR #28284) has broken PStack (jstack --mixed) behavior on macOS. It affects both AMD64 and AArch64. See JBS for details.

This PR fixes it to implement CFrame::toFrame.

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⚠️ Found leading lowercase letter in issue title for 8373110: jstack --mixed frames are broken on macOS after JDK-8371194

Issue

JDK-8373110: jstack --mixed frames are broken on macOS after JDK-8371194 (Bug - P3)

Reviewers

Chris Plummer (@plummercj - Reviewer)
Kevin Walls (@kevinjwalls - Reviewer)

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$ git fetch https://git.openjdk.org/jdk.git pull/28686/head:pull/28686
$ git checkout pull/28686

Update a local copy of the PR:
$ git checkout pull/28686
$ git pull https://git.openjdk.org/jdk.git pull/28686/head

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$ git pr checkout 28686

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bridgekeeper · 2025-12-06T02:36:38Z

👋 Welcome back ysuenaga! 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 · 2025-12-06T02:37:33Z

@YaSuenag 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:

8373110: jstack --mixed frames are broken on macOS after JDK-8371194

Reviewed-by: cjplummer, kevinw

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

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

3f20eb9: 8372348: Adjust some UL / JFR string deduplication output messages
a31e6e0: 8373593: Support latest VS2026 MSC_VER in abstract_vm_version.cpp
8598306: 8364766: C2: Improve Value() of DivI and DivL for non-constant inputs
... and 154 more: https://git.openjdk.org/jdk/compare/b0f59f6021a00dc569e08810b34db21553a5b68d...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

openjdk · 2025-12-06T02:38:07Z

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

serviceability

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.

mlbridge · 2025-12-07T01:42:36Z

Webrevs

shipilev

Drive-by comment:

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/bsd/aarch64/BsdAARCH64CFrame.java

plummercj · 2025-12-08T20:37:04Z

macosx-aarch64 looks fine, but it looks like there is still an issue on macosx-x64. Stack traces are empty:

"Reference Handler" #15 daemon prio=10 tid=0x00007f94c0820010 nid=29955 waiting on condition [0x000070000e080000]
   java.lang.Thread.State: RUNNABLE
   JavaThread state: _thread_blocked
0x00007ff803c3b6f6		????????

Before this change you at least got a partial stack followed by the UnsupportedPlatformException.

…sd/aarch64/BsdAARCH64CFrame.java Co-authored-by: Aleksey Shipilëv <shipilev@amazon.de>

YaSuenag · 2025-12-08T23:44:46Z

@plummercj

there is still an issue on macosx-x64. Stack traces are empty

Does it happen always? or intermittently?

Before this change you at least got a partial stack followed by the UnsupportedPlatformException.

I'm not sure, but I guess jstack could not unwind frame at some point(s) due to unwind info like DWARF on Linux - jstack might not handle call frame because the symbol could not be resolved.

plummercj · 2025-12-08T23:47:45Z

Does it happen always? or intermittently?

Always. Every thread and with every run. All of the thread stack traces just have the one empty frame.

YaSuenag · 2025-12-09T01:03:41Z

@plummercj Maybe it was fixed in the latest commit on this PR. Could you check again?

plummercj · 2025-12-09T02:42:42Z

@plummercj Maybe it was fixed in the latest commit on this PR. Could you check again?

That seems to have fixed it. Thanks!

plummercj · 2025-12-09T03:53:48Z

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/bsd/aarch64/BsdAARCH64CFrame.java

-      if ((fp == null) || fp.lessThan(rsp)) {
-        return null;
+   @Override
+   public CFrame sender(ThreadProxy thread, Address nextSP, Address nextFP, Address nextPC) {


Why is it that for aarch64 these are all "next" arguments, but for AMD64 they are not?

I want to declare like sender(ThreadProxy th, Address sp, Address fp, Address pc) as defined in CFrame, however name of parameters (sp, fp, pc) have already declared as class members in BsdAARCH64CFrame. Thus I added next as a prefix of parameter name.

Ok. Looks like that was also the case with LunuxAARCH64CFrame.

YaSuenag · 2025-12-17T13:31:02Z

PING: Can I get second reviewer(s)? Thanks!

kevinjwalls · 2025-12-17T19:06:22Z

src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/debugger/bsd/aarch64/BsdAARCH64CFrame.java

+        CodeCache cc = VM.getVM().getCodeCache();
+        CodeBlob currentBlob = cc.findBlobUnsafe(pc());
+
+        // This case is different from HotSpot. See JDK-8371194 for details.


Looks good overall I think.
What does "different from HotSpot" mean?
I see we used that phrase in 8371194 also in LinuxAARCH64CFrame.java
Maybe it is saying that these codeBlobs are handled differently from other code?

Yes. We were trying to implement similar code with NativeStackPrinter used in generating hs_err log in HotSpot, but this condition is different with it.

Comments in 8371195 says:

The special case for currentBlob.isContinuationStub() || currentBlob.isNativeMethod()) is needed compared to os::get_sender_for_C_frame because, unlike in the VM, here we are walking those frames as native C frames. Without the special case we depend on nextFP which might not be valid unless -XX:+PreserveFramePointer is used.

In os_bsd_aarch64.cpp, comment of get_sender_for_C_frame() says JVM compiled with -fno-omit-frame-pointer, but we can override CFLAGS with configure options. Thus I think it is better to align with Linux AArch64. Actually I heard this code works fine on Mac AArch64 - mixed jstack unwinded native methods successfully like java.lang.ref.Reference.waitForReferencePendingList().

OK, so this is different to the HotSpot NativeStackPrinter and the frame::next_frame() method.
As we already have the comment in a similar method maybe no need to change it here.
Thanks.

YaSuenag · 2025-12-18T13:14:38Z

Thanks a lot for your review!

/integrate

openjdk · 2025-12-18T13:15:38Z

Going to push as commit b848ddf.
Since your change was applied there have been 165 commits pushed to the master branch:

3258e4d: 8373068: Revisit details of Float16 to decimal conversion algorithm
629e4ac: 8372661: Add a null-safe static factory method to "jdk.test.lib.net.SimpleSSLContext"
2c0d9a7: 8373396: Min and Max Ideal missing AddNode::Ideal optimisations
... and 162 more: https://git.openjdk.org/jdk/compare/b0f59f6021a00dc569e08810b34db21553a5b68d...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-12-18T13:15:48Z

@YaSuenag Pushed as commit b848ddf.

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

8373110: jstack --mixed frames are broken on macOS after JDK-8371194

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openjdk bot added the serviceability serviceability-dev@openjdk.org label Dec 6, 2025

Override 2 "sender" method in Bsd CFrame classes

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YaSuenag marked this pull request as ready for review December 7, 2025 01:38

openjdk bot added the rfr Pull request is ready for review label Dec 7, 2025

shipilev reviewed Dec 8, 2025

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…sd/aarch64/BsdAARCH64CFrame.java Co-authored-by: Aleksey Shipilëv <shipilev@amazon.de>

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YaSuenag deleted the JDK-8373110 branch December 18, 2025 13:15

8373110: jstack --mixed frames are broken on macOS after JDK-8371194 #28686

8373110: jstack --mixed frames are broken on macOS after JDK-8371194 #28686

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