[PATCH bpf-next] bpf, arm64: sign return address for jited code

[Daniel Borkmann]

On 3/18/22 11:29 AM, Xu Kuohai wrote:
> Sign return address for jited code when the kernel is built with pointer
> authentication enabled.
> 
> 1. Sign lr with paciasp instruction before lr is pushed to stack. Since
>     paciasp acts like landing pads for function entry, no need to insert
>     bti instruction before paciasp.
> 
> 2. Authenticate lr with autiasp instruction after lr is poped from stack.
> 
> Signed-off-by: Xu Kuohai <xukuohai at huawei.com>

This would need a rebase, but please also use the commit description to provide
some more details how this inter-operates wrt BPF infra such as tail calls and
BPF-2-BPF calls when we look back into this in few months from now.

Thanks,
Daniel