linux-kernel - Re: [PATCH v4 06/10] modpost: Add modinfo flag to livepatch modules

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Message-ID: <CAK7LNAQuS-YcXecfJ21BGzc0CimzWxQcYST5-1xRgnCQGtcL4A@mail.gmail.com>
Date:   Wed, 31 Jul 2019 14:58:27 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Joe Lawrence <joe.lawrence@...hat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        live-patching@...r.kernel.org,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>
Subject: Re: [PATCH v4 06/10] modpost: Add modinfo flag to livepatch modules

Hi Joe,


On Thu, May 9, 2019 at 11:39 PM Joe Lawrence <joe.lawrence@...hat.com> wrote:
>
> From: Miroslav Benes <mbenes@...e.cz>
>
> Currently, livepatch infrastructure in the kernel relies on
> MODULE_INFO(livepatch, "Y") statement in a livepatch module. Then the
> kernel module loader knows a module is indeed livepatch module and can
> behave accordingly.
>
> klp-convert, on the other hand relies on LIVEPATCH_* statement in the
> module's Makefile for exactly the same reason.
>
> Remove dependency on modinfo and generate MODULE_INFO flag
> automatically in modpost when LIVEPATCH_* is defined in the module's
> Makefile. Generate a list of all built livepatch modules based on
> the .livepatch file and store it in (MODVERDIR)/livepatchmods. Give
> this list as an argument for modpost which will use it to identify
> livepatch modules.
>
> As MODULE_INFO is no longer needed, remove it.


I do not understand this patch.
This makes the implementation so complicated.

I think MODULE_INFO(livepatch, "Y") is cleaner than
LIVEPATCH_* in Makefile.


How about this approach?


[1] Make modpost generate the list of livepatch modules.
    (livepatch-modules)

[2] Generate Symbols.list in scripts/Makefile.modpost
    (vmlinux + modules excluding livepatch-modules)

[3] Run klp-convert for modules in livepatch-modules.


If you do this, you can remove most of the build system hacks
can't you?


I attached an example implementation for [1].

Please check whether this works.

Thanks.



-- 
Best Regards
Masahiro Yamada

View attachment "0001-livepatch-make-modpost-generate-the-list-of-livepatc.patch" of type "text/x-patch" (3983 bytes)