On Mon, 17 Mar 2025 19:37:48 GMT, Jiangli Zhou <jian...@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/Sou rceDebugExtension.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()); > } This seems reasonable to me. A couple of nits. Thanks src/hotspot/share/prims/jvmtiAgent.cpp line 360: > 358: // to try lookup_Agent_OnLoad_entry_point for Agent_OnLoad as well. > 359: OnLoadEntry_t on_load_entry = lookup_JVM_OnLoad_entry_point( > 360: this, /* vm exit on error */ false); Suggestion: OnLoadEntry_t on_load_entry = lookup_JVM_OnLoad_entry_point(this, /* vm exit on error */ false); src/hotspot/share/prims/jvmtiAgent.cpp line 365: > 363: if (on_load_entry == nullptr) { > 364: on_load_entry = lookup_Agent_OnLoad_entry_point( > 365: this, /* vm exit on error */ true); Suggestion: on_load_entry = lookup_Agent_OnLoad_entry_point(this, /* vm exit on error */ true); ------------- Marked as reviewed by dholmes (Reviewer). PR Review: https://git.openjdk.org/jdk/pull/24086#pullrequestreview-2692846277 PR Review Comment: https://git.openjdk.org/jdk/pull/24086#discussion_r2000148624 PR Review Comment: https://git.openjdk.org/jdk/pull/24086#discussion_r2000148978
