RFR: 8376269: Mixed jstack cannot find function in vDSO [v4]

[Kevin Walls]

On Tue, 3 Feb 2026 10:24:43 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

>> Some functions / signal trampoline would be provided by vDSO in Linux. However SA cannot find symbols in it because it is not a regular ELF, it is on the memory only.
>> For example, mixed jstack could not decode the symbol in the coredump crashed in gettimeofday(2) as following:
>> 
>> 
>> 0x00007faae3dd0818      VMError::report_and_die(Thread*, unsigned int, unsigned char*, void const*, void const*) + 0x58
>> 0x00007faae3aff1ba      JVM_handle_linux_signal + 0x42a
>> 0x00007faae4ad9290      <signal handler called>
>> 0x00007faae4cd8e69              ????????
>> 0x00007faaca78ffa1      <nep_invoker_blob>
>> 0x00007faaca73fd48      * java.lang.invoke.LambdaForm$MH+0x0000000028156c00.invoke(java.lang.Object, long, long, long) bci:12 (Interpreted frame)
>> 
>> 
>> It should be:
>> 
>> 
>> 0x00007fb5841d0818      VMError::report_and_die(Thread*, unsigned int, unsigned char*, void const*, void const*) + 0x58
>> 0x00007fb583eff1ba      JVM_handle_linux_signal + 0x42a
>> 0x00007fb584fd9290      <signal handler called>
>> 0x00007fb5851d8e69      __cvdso_gettimeofday_data.constprop.0 + 0x99
>> 0x00007fb56a78f321      <nep_invoker_blob>
>> 0x00007fb56a73fd48      * java.lang.invoke.LambdaForm$MH+0x000000000e156c00.invoke(java.lang.Object, long, long, long) bci:12 (Interpreted frame)
>> 
>> 
>> Some platforms (Ubuntu 24.04 and Fedora 43 at least) provide vDSO binary in `/lib/modules/<kernel version>/vdso`. This patch attempts to load it if we can refer it because we want to use debuginfo of vDSO if possible. Otherwise load vDSO memory.
>
> 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 eight additional commits since the last revision:
> 
>  - Update testcase to skip if kernel debuginfo is not available
>  - Merge branch 'master' into JDK-8376269
>  - Add new function to handle vDSO
>  - Remove unneeded change
>  - Remove 32 bit support
>  - Update src/jdk.hotspot.agent/linux/native/libsaproc/ps_core.c
>    
>    Co-authored-by: Chris Plummer <chris.plummer at oracle.com>
>  - Update src/jdk.hotspot.agent/linux/native/libsaproc/ps_core.c
>    
>    Co-authored-by: Chris Plummer <chris.plummer at oracle.com>
>  - 8376269: Mixed jstack cannot find function in vDSO

OK great, I see I have the vdso file in /lib/modules on my Oracle Linux, so that should work for me also.  Added a couple of questions, thanks.

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PR Comment: https://git.openjdk.org/jdk/pull/29400#issuecomment-3847125286