linux-kernel - Re: [PATCH v2 3/3] livepatch: Cleanup module page permission changes

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Message-ID: <871tc02j0b.fsf@rustcorp.com.au>
Date:	Mon, 09 Nov 2015 09:31:24 +1030
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Josh Poimboeuf <jpoimboe@...hat.com>,
	Petr Mladek <pmladek@...e.com>
Cc:	Seth Jennings <sjenning@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Vojtech Pavlik <vojtech@...e.com>,
	linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
	"Cyril B." <cbay@...aysdata.com>, Miroslav Benes <mbenes@...e.cz>
Subject: Re: [PATCH v2 3/3] livepatch: Cleanup module page permission changes

Josh Poimboeuf <jpoimboe@...hat.com> writes:
> On Fri, Nov 06, 2015 at 02:42:46PM +0100, Petr Mladek wrote:
>> naming schemes. What about adding into the public API?
>> 
>>   set_module_ro()
>>   set_module_rw()
>> 
>> It should modify everything: init, core, text, and data but only
>> the ro/rw flags.
>
> Even that naming is not without its problems.  For example,
> set_module_ro() is false advertising -- it wouldn't change *all* module
> memory to be read-only.  (It wouldn't touch the r/w data areas.)
>
> But I don't really care what the interfaces are called.  It's really
> Rusty's call.  I just stuck to the existing naming convention in the
> module code with the set/unset ro_nx stuff.

I'm looking at the ro/nx stuff now, and it seems like a mess.  For
example, set_all_modules_text_rw() and set_all_modules_text_ro() use
mod->core_text_size instead of mod->core_ro_size.  Which is probably
what they want (ftrace doesn't care about rodata) but pretty damn
confusing.

So I'll extend your cleanup.  Expect a patch for testing RSN...

Thanks,
Rusty.
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