[RFC PATCH] riscv: Implement HAVE_DYNAMIC_FTRACE_WITH_CALL_OPS

[Puranjay Mohan]

Hi Björn,

On Fri, Mar 8, 2024 at 11:16 AM Björn Töpel <bjorn at kernel.org> wrote:
> >
> > If I remember from Steven's talk, x86 uses dynamically allocated trampolines
> > for per callsite tracers, would CALL_OPS provide better performance than that?
>
> Probably not, and it was really a tongue-in-cheek comment -- nothing I
> encourage you to do!
>
> Now, I think a better approach for RISC-V would be implementing what x86
> has (arch_ftrace_update_trampoline()), rather than CALL_OPS for RISC-V.
>
> Thoughts?

I am going to spin some patches for implementing
arch_ftrace_update_trampoline() for
RISC-V, then we can compare the two approaches and see which is
better. But I agree
that arch_ftrace_update_trampoline() is a better approach given that
we can jump anywhere
with auipc/jalr.

Thanks,
Puranjay