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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Miroslav Benes <mbenes@suse.cz>
Cc: Joe Lawrence <joe.lawrence@redhat.com>,
	Petr Mladek <pmladek@suse.com>,
	jikos@kernel.org, linux-kernel@vger.kernel.org,
	live-patching@vger.kernel.org
Subject: Re: [RFC PATCH 2/2] livepatch: Clear relocation targets on a module removal
Date: Wed, 4 Sep 2019 21:32:02 -0500
Message-ID: <20190905023202.ed7fecc22xze4pwj@treble> (raw)
In-Reply-To: <alpine.LSU.2.21.1909031447140.3872@pobox.suse.cz>

On Tue, Sep 03, 2019 at 03:02:34PM +0200, Miroslav Benes wrote:
> On Mon, 2 Sep 2019, Joe Lawrence wrote:
> 
> > On 9/2/19 12:13 PM, Miroslav Benes wrote:
> > >> I can easily foresee more problems like those in the future.  Going
> > >> forward we have to always keep track of which special sections are
> > >> needed for which architectures.  Those special sections can change over
> > >> time, or can simply be overlooked for a given architecture.  It's
> > >> fragile.
> > > 
> > > Indeed. It bothers me a lot. Even x86 "port" is not feature complete in
> > > this regard (jump labels, alternatives,...) and who knows what lurks in
> > > the corners of the other architectures we support.
> > > 
> > > So it is in itself reason enough to do something about late module
> > > patching.
> > > 
> > 
> > Hi Miroslav,
> > 
> > I was tinkering with the "blue-sky" ideas that I mentioned to Josh the other
> > day.
> 
> > I dunno if you had a chance to look at what removing that code looks
> > like, but I can continue to flesh out that idea if it looks interesting:
> 
> Unfortunately no and I don't think I'll come up with something useful 
> before LPC, so anything is really welcome.
> 
> > 
> >   https://github.com/joe-lawrence/linux/tree/blue-sky

I like this a lot.

> > A full demo would require packaging up replacement .ko's with a livepatch, as
> > well as "blacklisting" those deprecated .kos, etc.  But that's all I had time
> > to cook up last week before our holiday weekend here.
> 
> Frankly, I'm not sure about this approach. I'm kind of torn. The current 
> solution is far from ideal, but I'm not excited about the other options 
> either. It seems like the choice is basically between "general but 
> technically complicated fragile solution with nontrivial maintenance 
> burden", or "something safer and maybe cleaner, but limiting for 
> users/distros". Of course it depends on whether the limitation is even 
> real and how big it is. Unfortunately we cannot quantify it much and that 
> is probably why our opinions (in the email thread) differ.

How would this option be "limiting for users/distros"?  If the packaging
part of the solution is done correctly then I don't see how it would be
limiting.

-- 
Josh

  parent reply index

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-19 12:28 [RFC PATCH 0/2] " Miroslav Benes
2019-07-19 12:28 ` [PATCH 1/2] livepatch: Nullify obj->mod in klp_module_coming()'s error path Miroslav Benes
2019-07-28 19:45   ` Josh Poimboeuf
2019-08-19 11:26     ` Petr Mladek
2019-07-19 12:28 ` [RFC PATCH 2/2] livepatch: Clear relocation targets on a module removal Miroslav Benes
2019-07-22  9:33   ` Petr Mladek
2019-08-14 12:33     ` Miroslav Benes
2019-07-28 20:04   ` Josh Poimboeuf
2019-08-14 11:06     ` Miroslav Benes
2019-08-14 15:12       ` Josh Poimboeuf
2019-08-16  9:46         ` Petr Mladek
2019-08-22 22:36           ` Josh Poimboeuf
2019-08-23  8:13             ` Petr Mladek
2019-08-26 14:54               ` Josh Poimboeuf
2019-08-27 15:05                 ` Joe Lawrence
2019-08-27 15:37                   ` Josh Poimboeuf
2019-09-02 16:13                 ` Miroslav Benes
2019-09-02 17:05                   ` Joe Lawrence
2019-09-03 13:02                     ` Miroslav Benes
2019-09-04  8:49                       ` Petr Mladek
2019-09-04 16:26                         ` Joe Lawrence
2019-09-05  2:50                         ` Josh Poimboeuf
2019-09-05 11:09                           ` Petr Mladek
2019-09-05 11:19                             ` Jiri Kosina
2019-09-05 13:23                               ` Josh Poimboeuf
2019-09-05 13:31                                 ` Jiri Kosina
2019-09-05 13:42                                   ` Josh Poimboeuf
2019-09-05 11:39                             ` Joe Lawrence
2019-09-05 13:08                             ` Josh Poimboeuf
2019-09-05 13:15                               ` Josh Poimboeuf
2019-09-05 13:52                                 ` Petr Mladek
2019-09-05 14:28                                   ` Josh Poimboeuf
2019-09-05 12:03                           ` Miroslav Benes
2019-09-05 12:35                             ` Josh Poimboeuf
2019-09-05 12:49                               ` Miroslav Benes
2019-09-05 11:52                         ` Miroslav Benes
2019-09-05  2:32                       ` Josh Poimboeuf [this message]
2019-09-05 12:16                         ` Miroslav Benes
2019-09-05 12:54                           ` Josh Poimboeuf
2019-09-06 12:51                             ` Miroslav Benes
2019-09-06 15:38                               ` Joe Lawrence
2019-09-06 16:45                               ` Josh Poimboeuf
2019-08-26 13:44         ` Nicolai Stange
2019-08-26 15:02           ` Josh Poimboeuf

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