RFR: 8352098: -Xrunjdwp fails on static JDK [v2]

[Chris Plummer]

On Tue, 18 Mar 2025 16:54:51 GMT, Jiangli Zhou <jiangli at openjdk.org> wrote:

>> Please review this fix that avoids `JvmtiAgent::convert_xrun_agent` from prematurely exiting VM if `lookup_On_Load_entry_point` cannot load the agent using `JVM_OnLoad` symbol. Thanks
>> 
>> `lookup_On_Load_entry_point` first tries to load the builtin agent from the executable by checking the requested symbol (`JVM_OnLoad`). If no builtin agent is found, it then tries to load the agent shared library (e.g. `libjdwp.so`) by calling `load_library`. The issue is that `load_library` is called with `vm_exit_on_error` set to `true`, which causes the VM to exit immediately if the agent shared library is not loaded. Therefore, `JvmtiAgent::convert_xrun_agent` has no chance to try loading the agent using `Agent_OnLoad` symbol (https://github.com/openjdk/jdk/blob/19154f7af34bf6f13d61d7a9f05d6277964845d8/src/hotspot/share/prims/jvmtiAgent.cpp#L352). This is a hidden issue on regular JDK, since the `load_library` can successfully find the agent shared library when `JvmtiAgent::convert_xrun_agent` first tries to load the agent using `JVM_OnLoad` symbol. The issue is noticed on static JDK as there is no `libjdwp.so` in static JDK. It can be reproduced with jtreg `runtime/6294277/So
 urceDebugExtension.java` test.
>> 
>> As part of the fix, I cleaned up following in `invoke_JVM_OnLoad` and `invoke_Agent_OnLoad`. If there's an error, the VM should already have exited during `lookup_<JVM|Agent>_OnLoad_entry_point` in those cases.
>> 
>> 
>>   if (on_load_entry == nullptr) {
>>     vm_exit_during_initialization("Could not find ... function in -Xrun library", agent->name());
>>   }
>
> Jiangli Zhou has updated the pull request incrementally with two additional commits since the last revision:
> 
>  - Apply @dholmes-ora's edit suggestion.
>    
>    Co-authored-by: David Holmes <62092539+dholmes-ora at users.noreply.github.com>
>  - Apply @dholmes-ora's suggestion to use single line.
>    
>    Co-authored-by: David Holmes <62092539+dholmes-ora at users.noreply.github.com>

I had a look yesterday and it looked good, and your latest changes look good also.

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Marked as reviewed by cjplummer (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/24086#pullrequestreview-2695605225