linux-kernel - Re: module: s390: keep mod_arch_specific for livepatch modules

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Message-ID: <20160204210318.GP22854@treble.redhat.com>
Date:	Thu, 4 Feb 2016 15:03:18 -0600
From:	Josh Poimboeuf <jpoimboe@...hat.com>
To:	Jessica Yu <jeyu@...hat.com>
Cc:	Rusty Russell <rusty@...tcorp.com.au>,
	Seth Jennings <sjenning@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Vojtech Pavlik <vojtech@...e.com>,
	Jonathan Corbet <corbet@....net>,
	Miroslav Benes <mbenes@...e.cz>, linux-api@...r.kernel.org,
	live-patching@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: module: s390: keep mod_arch_specific for livepatch modules

On Wed, Feb 03, 2016 at 08:37:52PM -0500, Jessica Yu wrote:
> +++ Jessica Yu [03/02/16 20:11 -0500]:
> >Livepatch needs to utilize the symbol information contained in the
> >mod_arch_specific struct in order to be able to call the s390
> >apply_relocate_add() function to apply relocations. Keep a reference to
> >syminfo if the module is a livepatch module. Remove the redundant vfree()
> >in module_finalize() since module_arch_freeing_init() (which also frees
> >those structures) is called in do_init_module(). If the module isn't a
> >livepatch module, we free the structures in module_arch_freeing_init() as
> >usual.
> >
> >Signed-off-by: Jessica Yu <jeyu@...hat.com>
> >---
> >arch/s390/kernel/module.c | 7 +++++--
> >1 file changed, 5 insertions(+), 2 deletions(-)
> 
> I must note that I have verified that the patchset boots on s390 and
> that the sample livepatch module still works ...so that's good, but
> not saying much since what we really want is to test the relocation
> code. The kpatch build scripts however currently only support x86, so
> the next step is for me to port the kpatch scripts to s390 before I
> can really test this patchset. This in itself might take a while, so
> in the meantime I'd like to just collect another round of comments and
> feedback for v4.

I haven't reviewed the code yet, but otherwise I'm thinking it would
actually be fine to merge this patch set before testing with s390
relocations.  They aren't implemented on s390 today anyway, so there
can't be a regression if nobody is using it.

-- 
Josh