RFR: 8277204: Implement PAC-RET branch protection on Linux/AArch64 [v18]

[Andrew Haley]

On Mon, 7 Feb 2022 12:01:18 GMT, Alan Hayward <duke at openjdk.java.net> wrote:

> PreserveFramePointer is doing some additional stuff. I'll give it a test to make sure everything still works with PreserveFramePointer fully set. It would make things easier just to force it set with rop protection on.

Using PreserveFramePointer greatly simplifies the testing matrix, and has little adverse performance impact beyond disallowing C2 from allocating FP as a scratch register. It also simplifies this patch, which would be a very Good Thing. Let's do it.

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

PR: https://git.openjdk.java.net/jdk/pull/6334