8283784: java_lang_String::as_platform_dependent_str stores to oop in native state

[jyma22]

Hi all,

This pull request contains a backport of commit c9a469a from the openjdk/jdk repository.

The commit being backported was authored by David Holmes on Mar 30 2022 and was reviewed by Kim Barrett, Aleksey Shipilev, and Stefan Karlsson.

Thanks!

---

Progress

• [x] Change must not contain extraneous whitespace
• [ ] JDK-8283784 needs maintainer approval
• [x] Commit message must refer to an issue

Issue

• JDK-8283784: java_lang_String::as_platform_dependent_str stores to oop in native state (Bug - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk17u-dev.git pull/3988/head:pull/3988
$ git checkout pull/3988

Update a local copy of the PR:
$ git checkout pull/3988
$ git pull https://git.openjdk.org/jdk17u-dev.git pull/3988/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 3988

View PR using the GUI difftool:
$ git pr show -t 3988

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk17u-dev/pull/3988.diff

[bridgekeeper[bot]]

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[openjdk[bot]]

❗ This change is not yet ready to be integrated. See the Progress checklist in the description for automated requirements.

[openjdk[bot]]

⚠️ @jyma22 This pull request contains merges that bring in commits not present in the target repository. Since this is not a "merge style" pull request, these changes will be squashed when this pull request in integrated. If this is your intention, then please ignore this message. If you want to preserve the commit structure, you must change the title of this pull request to Merge <project>:<branch> where <project> is the name of another project in the OpenJDK organization (for example Merge jdk:master).

[jyma22]

/signed

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[openjdk[bot]]

This backport pull request has now been updated with issue from the original commit.

[jyma22]

/approval request adjusts the block scope so that JNIHandles::destroy_local is called once we are back in VM, and so no longer safepoint-safe

[openjdk[bot]]

@jyma22 8283784: The approval request has been created successfully.

[mlbridge[bot]]

Webrevs

• 00: Full (0e1af44d)

[GoeLin]

HI @jyma22 please read https://wiki.openjdk.org/display/JDKUpdates/How+to+contribute+or+backport+a+fix and give a fix request comment with the required information.

[openjdk[bot]]

⚠️ @jyma22 This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[jyma22]

Fix Request 17u

Backprting this patch eliminates the critical JNIHandles safepoint safety issue. The change adjusts block scope to ensure JNIHandles::destroy_local is called when back in VM state, which is a targeted fix that doesn't affect core functionality. Path applies cleanly to 17u. Included test passes. Ran tier1-3 as sanity check with no regressions observed.