[PATCH v2] arm64: implement support for static call trampolines

[Peter Zijlstra]

On Wed, Oct 28, 2020 at 07:41:14PM +0100, Ard Biesheuvel wrote:
> This turned nasty really quickly when I realized that any sleeping task
> could have been interrupted right in the middle of the ADRP/ADD pair
> that we emit for static call targets that are out of immediate branching
> range.

Ha! Yes, that's a 'problem' allright. On x86 we normally only patch a
single instruction because of this, however we have some kprobe code
that has this issue and there we use tasks_rcu when PREEMPT=y.

Now, let me try and read this patch properly..