Re: [PATCH v3] PowerPC: Replace kretprobe with rethook

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Tue, 09 Jul 2024 12:28:29 +0530
Naveen N Rao <naveen@kernel.org> wrote:

> Masami Hiramatsu wrote:
> > On Thu, 27 Jun 2024 09:21:01 -0400
> > Abhishek Dubey <adubey@linux.ibm.com> wrote:
> > 
> >> +/* rethook initializer */
> >> +int __init arch_init_kprobes(void)
> >> +{
> >> +	return register_kprobe(&trampoline_p);
> >> +}
> > 
> > No, please don't use arch_init_kprobes() for initializing rethook, since
> > rethook is used from fprobe too (at this moment).
> > 
> > If you want to make it relays on kprobes, you have to make a dependency
> > in powerpc's kconfig, e.g.
> > 
> > select HAVE_RETHOOK if KPROBES
> > 
> > But I don't recommend it.
> 
> Given that kretprobe has always worked this way on powerpc, I think this
> is a fair tradeoff. We get to enable fprobes on powerpc only if kprobes
> is also enabled.
> 
> Longer term, it would certainly be nice to get rid of that probe, and to
> expand the trampoline to directly invoke the rethook callback.

OK. In longer term, rethook will be only for kretprobe, and kretprobe
will be replaced by fprobe[1]. So please comment it and add that 

[1] https://lore.kernel.org/all/172000134410.63468.13742222887213469474.stgit@devnote2/

Thank you,

> 
> 
> Thanks,
> Naveen


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>