RFR: 8283689: Update the foreign linker VM implementation [v7]

[Jorn Vernee]

On Wed, 11 May 2022 16:38:54 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

>> If you want to avoid processing asynchronous exceptions during this upcall you could block them (check NoAsyncExceptionDeliveryMark in JavaThread::exit()). Seems you could set the flag in ProgrammableUpcallhandler::on_entry() and unset it back on ProgrammableUpcallhandler::on_exit(). While that flag is set any asynchronous exception in the handshake queue of this thread will be skipped from processing. Maybe we should add a public method in the JavaThread class, block_async_exceptions()/unblock_async_exceptions() so we hide the handshake implementation.
>
> Oh nice! I was just thinking that the only possible way out of this conundrum would be to somehow block the delivery of async exceptions (at least outside of the user's exception handler). So, that seems to be exactly what we need :)

I went ahead and implemented this suggestion. Now we block async exceptions in on_entry, and unblock in on_exit.

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PR: https://git.openjdk.java.net/jdk/pull/7959