Re: [PATCH bpf-next v5 1/6] arm64: ftrace: Add ftrace direct call support

[KP Singh]

On Wed, May 18, 2022 at 3:53 PM Xu Kuohai <xukuohai@xxxxxxxxxx> wrote:
>
> Add ftrace direct support for arm64.
>
> 1. When there is custom trampoline only, replace the fentry nop to a
>    jump instruction that jumps directly to the custom trampoline.
>
> 2. When ftrace trampoline and custom trampoline coexist, jump from
>    fentry to ftrace trampoline first, then jump to custom trampoline
>    when ftrace trampoline exits. The current unused register
>    pt_regs->orig_x0 is used as an intermediary for jumping from ftrace
>    trampoline to custom trampoline.
>
> Signed-off-by: Xu Kuohai <xukuohai@xxxxxxxxxx>
> Acked-by: Song Liu <songliubraving@xxxxxx>

Acked-by: KP Singh <kpsingh@xxxxxxxxxx>