RFR: 8374482: SA does not handle signal handler frame in mixed jstack [v4]

[Yasumasa Suenaga]

On Sun, 11 Jan 2026 07:33:12 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

>> SA does not handle signal handler frame in mixed jstack as following:
>> 
>> 
>> ----------------- 1789 -----------------
>> "main" #1 prio=5 tid=0x00007f654c010000 nid=0x6fd runnable [0x00007f6551c0b000]
>>    java.lang.Thread.State: RUNNABLE
>>    JavaThread state: _thread_in_native
>> 0x00007f6551c0e735 __GI_abort + 0x8b
>> 0x00007f65511feb39 _ZN2os5abortEbPvPKv + 0x19
>> 0x00007f6551427569 _ZN7VMError14report_and_dieEiPKcS1_P13__va_list_tagP6ThreadPhPvS7_S1_im + 0x579
>> 0x00007f6551427deb _ZN7VMError14report_and_dieEP6ThreadjPhPvS3_PKcz + 0x8b
>> 0x00007f6551427e1e _ZN7VMError14report_and_dieEP6ThreadjPhPvS3_ + 0x1e
>> 0x00007f6551209950 JVM_handle_linux_signal + 0x1c0
>> 0x00007f65511fd538 _ZL13signalHandleriP7siginfoPv + 0x38
>> 0x00007f6551c27290 ????????
>> 0x00007f653400f890 * NativeSEGV.doSEGV() bci:0 (Interpreted frame)
>> 0x00007f6534009c43 * NativeSEGV.main(java.lang.String[]) bci:76 line:37 (Interpreted frame)
>> 0x00007f6534000849 <StubRoutines>
>> 0x00007f6550e847e9 _ZN9JavaCalls11call_helperEP9JavaValueRK12methodHandleP17JavaCallArgumentsP6Thread + 0x3b9
>> 0x00007f6550eff1ba _ZL17jni_invoke_staticP7JNIEnv_P9JavaValueP8_jobject11JNICallTypeP10_jmethodIDP18JNI_ArgumentPusherP6Thread.isra.65.constprop.193 + 0x1ba
>> 0x00007f6550f01824 jni_CallStaticVoidMethod + 0x164
>> 0x00007f6551e0582d JavaMain + 0xe4d
>> 0x00007f6551c7f464 start_thread + 0x2e4
>> 
>> 0x7f6551c27290 is a signal handler frame, and its caller is native frame. However jstack reports the caller is Java frame (`NativeSEGV.doSEGV()`).
>> 
>> It should be like following:
>> 
>> 
>> 0x00007fdbd170321a JVM_handle_linux_signal + 0x42a
>> 0x00007fdbd267b290 <signal handler called>
>> 0x00007fdbc7ecb3b1 Java_NativeSEGV_doSEGV + 0x18
>> 0x00007fdbb67468ba * NativeSEGV.doSEGV() bci:0 (Interpreted frame)
>> 
>> 
>> This is long standing bug (since JDK 9 at least).
>
> Yasumasa Suenaga has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains five additional commits since the last revision:
> 
>  - Merge remote-tracking branch 'origin/master' into jhsdb-jstack-sighandler
>  - Merge remote-tracking branch 'origin/master' into jhsdb-jstack-sighandler
>  - Merge remote-tracking branch 'origin/master' into jhsdb-jstack-sighandler
>  - Fix
>  - 8374482: SA does not handle signal handler frame in mixed jstack

This PR aims to handle signal handler correctly - mixed jstack can be unwind the problematic call frame as a result. Then we can get correct SP/BP/PC, so we can unwind entire of call stacks including Java.
We can (should) use native debugger to analyze native frames of course, but it is difficult to unwind Java frames - I think Java frames is important for Java developers because most of native calls come from Java.

I completely agree this PR increases technical debt, so I give big +1 to use 3rd party unwinder like libunwind, but I think it is better to fix as possible if it is difficult to use it.

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PR Comment: https://git.openjdk.org/jdk/pull/29023#issuecomment-3752226194