Re: [RFC][PATCH 0/4] Make bpf_jit and kprobes work with CONFIG_MODULES=n

From: Song Liu <song@kernel.org>
To: Calvin Owens <jcalvinowens@gmail.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
	Christophe Leroy <christophe.leroy@csgroup.eu>,
	 Mike Rapoport <rppt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	 Alexei Starovoitov <ast@kernel.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	 Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	 Masami Hiramatsu <mhiramat@kernel.org>,
	Naveen N Rao <naveen.n.rao@linux.ibm.com>,
	 Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
	David S Miller <davem@davemloft.net>,
	 Thomas Gleixner <tglx@linutronix.de>,
	bpf@vger.kernel.org, linux-modules@vger.kernel.org,
	 linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH 0/4] Make bpf_jit and kprobes work with CONFIG_MODULES=n
Date: Wed, 6 Mar 2024 17:58:14 -0800	[thread overview]
Message-ID: <CAPhsuW4UA9uCRK7EVCJGUvmroQhZZZiVdXotri4oO7+WRQr3sg@mail.gmail.com> (raw)
In-Reply-To: <Zej66vQInnDYgpNy@gmail.com>

Hi Calvin,

It is great to hear from you! :)

On Wed, Mar 6, 2024 at 3:23 PM Calvin Owens <jcalvinowens@gmail.com> wrote:
>
> On Wednesday 03/06 at 13:34 -0800, Luis Chamberlain wrote:
> > On Wed, Mar 06, 2024 at 12:05:07PM -0800, Calvin Owens wrote:
> > > Hello all,
> > >
> > > This patchset makes it possible to use bpftrace with kprobes on kernels
> > > built without loadable module support.
> >
> > This is a step in the right direction for another reason: clearly the
> > module_alloc() is not about modules, and we have special reasons for it
> > now beyond modules. The effort to share a generalize a huge page for
> > these things is also another reason for some of this but that is more
> > long term.
> >
> > I'm all for minor changes here so to avoid regressions but it seems a
> > rename is in order -- if we're going to all this might as well do it
> > now. And for that I'd just like to ask you paint the bikeshed with
> > Song Liu as he's been the one slowly making way to help us get there
> > with the "module: replace module_layout with module_memory",
> > and Mike Rapoport as he's had some follow up attempts [0]. As I see it,
> > the EXECMEM stuff would be what we use instead then. Mike kept the
> > module_alloc() and the execmem was just a wrapper but your move of the
> > arch stuff makes sense as well and I think would complement his series
> > nicely.
>
> I apologize for missing that. I think these are the four most recent
> versions of the different series referenced from that LWN link:
>
>   a) https://lore.kernel.org/all/20230918072955.2507221-1-rppt@kernel.org/
>   b) https://lore.kernel.org/all/20230526051529.3387103-1-song@kernel.org/
>   c) https://lore.kernel.org/all/20221107223921.3451913-1-song@kernel.org/
>   d) https://lore.kernel.org/all/20201120202426.18009-1-rick.p.edgecombe@intel.com/
>
> Song and Mike, please correct me if I'm wrong, but I think what I've
> done here (see [1], sorry for not adding you initially) is compatible
> with everything both of you have recently proposed above. How do you
> feel about this as a first step?

I agree that the work here is compatible with other efforts. I have no
objection to making this the first step.

>
> For naming, execmem_alloc() seems reasonable to me? I have no strong
> feelings at all, I'll just use that going forward unless somebody else
> expresses an opinion.

I am not good at naming things. No objection from me to "execmem_alloc".

Thanks,
Song