Live-Patching Archive on lore.kernel.org
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From: Peter Zijlstra <peterz@infradead.org>
To: Petr Mladek <pmladek@suse.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	rostedt@goodmis.org, mhiramat@kernel.org, bristot@redhat.com,
	jbaron@akamai.com, torvalds@linux-foundation.org,
	tglx@linutronix.de, mingo@kernel.org, namit@vmware.com,
	hpa@zytor.com, luto@kernel.org, ard.biesheuvel@linaro.org,
	jeyu@kernel.org, live-patching@vger.kernel.org
Subject: Re: [PATCH v4 15/16] module: Move where we mark modules RO,X
Date: Fri, 25 Oct 2019 11:16:34 +0200
Message-ID: <20191025091634.GA4114@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191025064456.6jjrngm4m3mspaxw@pathway.suse.cz>

On Fri, Oct 25, 2019 at 08:44:56AM +0200, Petr Mladek wrote:
> On Thu 2019-10-24 15:16:34, Peter Zijlstra wrote:

> > Right, that really should be able to run early. Esp. after commit
> > 
> >   11e86dc7f274 ("x86/paravirt: Detect over-sized patching bugs in paravirt_patch_call()")
> > 
> > paravirt patching is unconditional. We _never_ run with the indirect
> > call except very early boot, but modules should have them patched way
> > before their init section runs.
> > 
> > We rely on this for spectre-v2 and friends.
> 
> Livepatching has the same requirement. The module code has to be fully
> livepatched before the module gets actually used.

Right, and that is just saying that all paravirt RELAs (pv_ops) can
basically be deleted from modules.

Which avoids the reported problem in yet another way.

> It means before mod->init() is called and before the module is moved
> into MODULE_STATE_LIVE state.

Funny thing, currently ftrace is running code before all that. It runs
code before klp_module_coming(), before jump_label patching.

My other patch in this thread fixes that.

      parent reply index

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20191018073525.768931536@infradead.org>
     [not found] ` <20191018074634.801435443@infradead.org>
     [not found]   ` <20191021135312.jbbxsuipxldocdjk@treble>
     [not found]     ` <20191021141402.GI1817@hirez.programming.kicks-ass.net>
     [not found]       ` <20191023114835.GT1817@hirez.programming.kicks-ass.net>
2019-10-23 17:00         ` Josh Poimboeuf
2019-10-24 13:16           ` Peter Zijlstra
2019-10-25  6:44             ` Petr Mladek
2019-10-25  8:43               ` Peter Zijlstra
2019-10-25 10:06                 ` Peter Zijlstra
2019-10-25 13:50                   ` Josh Poimboeuf
2019-10-26  1:17                   ` Josh Poimboeuf
2019-10-28 10:07                     ` Peter Zijlstra
2019-10-28 10:43                     ` Peter Zijlstra
2019-10-25  9:16               ` Peter Zijlstra [this message]

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