Re: [PATCH v4 14/15] kprobes: remove dependency on CONFIG_MODULES

Mike Rapoport
2024-04-20T07:35:01Z

On Fri, Apr 19, 2024 at 03:59:40PM +0000, Christophe Leroy wrote:
>
>
> Le 19/04/2024 à 17:49, Mike Rapoport a écrit :
> > Hi Masami,
> >
> > On Thu, Apr 18, 2024 at 06:16:15AM +0900, Masami Hiramatsu wrote:
> >> Hi Mike,
> >>
> >> On Thu, 11 Apr 2024 19:00:50 +0300
> >> Mike Rapoport <rppt@kernel.org> wrote:
> >>
> >>> From: "Mike Rapoport (IBM)" <rppt@kernel.org>
> >>>
> >>> kprobes depended on CONFIG_MODULES because it has to allocate memory for
> >>> code.
> >>>
> >>> Since code allocations are now implemented with execmem, kprobes can be
> >>> enabled in non-modular kernels.
> >>>
> >>> Add #ifdef CONFIG_MODULE guards for the code dealing with kprobes inside
> >>> modules, make CONFIG_KPROBES select CONFIG_EXECMEM and drop the
> >>> dependency of CONFIG_KPROBES on CONFIG_MODULES.
> >>
> >> Thanks for this work, but this conflicts with the latest fix in v6.9-rc4.
> >> Also, can you use IS_ENABLED(CONFIG_MODULES) instead of #ifdefs in
> >> function body? We have enough dummy functions for that, so it should
> >> not make a problem.
> >
> > The code in check_kprobe_address_safe() that gets the module and checks for
> > __init functions does not compile with IS_ENABLED(CONFIG_MODULES).
> > I can pull it out to a helper or leave #ifdef in the function body,
> > whichever you prefer.
>
> As far as I can see, the only problem is MODULE_STATE_COMING.
> Can we move 'enum module_state' out of #ifdef CONFIG_MODULES in module.h ?

There's dereference of 'struct module' there:

(*probed_mod)->state != MODULE_STATE_COMING) {
...
}

so moving out 'enum module_state' won't be enough.

> >
> >> --
> >> Masami Hiramatsu
> >

--
Sincerely yours,
Mike.