RFR: 8282306: os::is_first_C_frame(frame*) crashes on invalid link access [v3]

[David Holmes]

On Wed, 23 Feb 2022 22:51:44 GMT, Johannes Bechberger <duke at openjdk.java.net> wrote:

>> This PR introduces a new method `can_access_link` into the frame class to check the accessibility of the link information. It furthermore adds a new `os::is_first_C_frame(frame*, Thread*)` that uses the `can_access_link` method
>> and the passed thread object to check the validity of frame pointer, stack pointer, sender frame pointer and sender stack pointer. This should reduce the possibilities for crashes.
>
> Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Use safefetch

This approach looks much better/cleaner - thanks.

Do we have any crash tests we can use to verify this?

Thanks,
David

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PR: https://git.openjdk.java.net/jdk/pull/7591