RFR: 8268339: Upstream: 8267989: Exceptions thrown during upcalls should be handled (Pt. 2)

[openjdk-notifier [bot]]

On Mon, 7 Jun 2021 16:38:01 GMT, Jorn Vernee <jvernee at openjdk.org> wrote:

> Hi,
> 
> This is part 2 of a two part upstreaming process of the patch mentioned in the subject line. The patch was split into 2 in order to document 2 separate specification changes that arose from a change in the implementation, with 2 separate CSRs. The first patch can be found here: https://github.com/openjdk/jdk/pull/4395
> 
> This patch adds uniform exception handling for exceptions thrown during FLA upcalls. Currently, these exceptions are either handled similarly to the VMs `CATCH` macro, or ignored after which control returns to unsuspecting native code, until control returns to Java, which will then handle the exception. The handling depends on the invocation mode.
> 
> Both of these are bad. The former because a stack trace is not printed and instead the VM exits with a fatal error. The latter is bad because an upcall completing abruptly and returning to native code which has no idea an exception occurred is unsafe, in the sense that invariants about the state of the program that the native code depends on might no longer hold.
> 
> This patch adds uniform exception handling that replaces both of these cases (see `SharedUtils::handleUncaughtException`), which prints the exception stack trace, and then unconditionally exits the VM, which is the only safe course of action at that point.
> 
> Exceptions thrown by upcalls should instead be handled during the upcall itself, for instance by translating the exception into an error code that is then returned to the native caller, which can deal with it appropriately.
> 
> See also the original review for panama-foreign: https://github.com/openjdk/panama-foreign/pull/543
> 
> Thanks,
> Jorn
> 
> Testing: `jdk_foreign` test suite.
> 
> Thanks,
> Jorn

The dependent pull request has now been integrated, and the target branch of this pull request has been updated. This means that changes from the dependent pull request can start to show up as belonging to this pull request, which may be confusing for reviewers. To remedy this situation, simply merge the latest changes from the new target branch into this pull request by running commands similar to these in the local repository for your personal fork:


git checkout Upstream_Excp_Hndl
git fetch https://git.openjdk.java.net/jdk master
git merge FETCH_HEAD
# if there are conflicts, follow the instructions given by git merge
git commit -m "Merge master"
git push

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PR: https://git.openjdk.java.net/jdk/pull/4396