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 [thread overview]
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.
prev parent reply other threads:[~2019-10-25 9:16 UTC|newest]
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 ` [PATCH v4 15/16] module: Move where we mark modules RO,X 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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