We could see jtreg test failure in TestJhsdbJstackMixedWithXComp.java due to unable unwinding from continuation stub. SA could unwind mixed call stacks since [JDK-8377946](https://bugs.openjdk.org/browse/JDK-8377946), and enabled TestJhsdbJstackMixedWithXComp tests in it. Hence the problem has been suffered. The problem was reported in Valhalla, but it is potential to happen on upstream, thus I proposed the fix to upstream.
There are 2 problems in LinuxAARCH64CFrame: 1. On AArch64 which disables `PreserveFramePointer`, we cannot believe FP to unwind call stacks, thus we might not be able to unwind call stacks from Java frame (includes code blobs). 2. In continuation stub, we need to get SP/FP/PC from continuation entry. So I fixed them in this PR, and it works on both upstream and Valhalla. --------- - [x] I confirm that I make this contribution in accordance with the [OpenJDK Interim AI Policy](https://openjdk.org/legal/ai). ------------- Commit messages: - 8382548: serviceability/sa/TestJhsdbJstackMixedWithXComp.java#xcomp-disable-tiered-compilation failed with Test failed! Changes: https://git.openjdk.org/jdk/pull/30959/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=30959&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8382548 Stats: 29 lines in 1 file changed: 21 ins; 0 del; 8 mod Patch: https://git.openjdk.org/jdk/pull/30959.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/30959/head:pull/30959 PR: https://git.openjdk.org/jdk/pull/30959
