Re: [PATCH] ARM: module: treat exit sections the same as init sections when !CONFIG_MODULE_UNLOAD

[Jessica Yu]

+++ Russell King - ARM Linux admin [07/05/21 13:30 +0100]:
> On Fri, May 07, 2021 at 02:13:22PM +0200, Jessica Yu wrote:
> > Dynamic code patching (alternatives, jump_label and static_call) can
> > have sites in __exit code, even if __exit is never executed. Therefore
> > __exit must be present at runtime, at least for as long as __init code is.
> ...
> > Previously, the module loader never loaded the exit sections in the first
> > place when CONFIG_MODULE_UNLOAD=n. Commit 33121347fb1c ("module: treat exit
> > sections the same as init sections when !CONFIG_MODULE_UNLOAD") addressed
> > the issue by having the module loader load the exit sections and then making
> > __exit identify as __init for !MODULE_UNLOAD. Then, since they are treated
> > like init sections, they will be also discarded after init.
> >
> > That commit satisfied the above requirements for jump_labels and
> > static_calls by modifying the checks in the core module_init_section()
> > function in kernel/module.c to include exit sections. However, ARM
> > overrides these and implements their own module_{init,exit}_section()
> > functions. Add a similar check for exit sections to ARM's
> > module_init_section() function so that all arches are on the same page.
>
> Shouldn't the module core code itself be doing:
>
> 	module_init_section(name) || module_exit_section(name)
>
> itself when CONFIG_MODULE_UNLOAD is not set, rather than pushing this
> logic down into every module_init_section() implementation?

Yeah, that sounds better. Originally, I had wanted to keep the #ifndef
in one place to keep the churn to a minimum.

But seeing that we have to patch up ARM too, it's probably the less
ugly option now. Let me cook up an alternative patch and resend.

Thanks,

Jessica