linux-kernel - Re: [PATCH] ARM: module: treat exit sections the same as init sections when !CONFIG_MODULE

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Message-ID: <20210507123054.GD1336@shell.armlinux.org.uk>
Date:   Fri, 7 May 2021 13:30:55 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Jessica Yu <jeyu@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ARM: module: treat exit sections the same as init
 sections when !CONFIG_MODULE_UNLOAD

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?

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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