[jdk21u-dev] RFR: 8345296: AArch64: VM crashes with SIGILL when prctl is disallowed [v3]

[Kerem Kat]

> Ref. https://github.com/openjdk/jdk/pull/22479
> 
>> We have caught this in some prod environments, where prctl is forbidden by the sandboxing mechanism. This fails the JVM
> 
> Does not apply cleanly, the backport depends on `FloatRegister` changes from [JDK-8339063](https://bugs.openjdk.org/browse/) which are included in `src/hotspot/cpu/aarch64/register_aarch64.hpp`.
> 
> Additional testing:
> 
> - [x] Verified the bug is fixed with the seccomp repro from [JDK-8345296](https://bugs.openjdk.org/browse/JDK-8345296?focusedId=14727386&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-14727386): Segfault without the patch, works with.

Kerem Kat has updated the pull request incrementally with one additional commit since the last revision:

  Fix linux-cross-compile aarch64 build.

-------------

Changes:
  - all: https://git.openjdk.org/jdk21u-dev/pull/1222/files
  - new: https://git.openjdk.org/jdk21u-dev/pull/1222/files/3fc28084..704459c2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1222&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1222&range=01-02

  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1222.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1222/head:pull/1222

PR: https://git.openjdk.org/jdk21u-dev/pull/1222