linux-kernel - Re: [PATCH v2 0/6] x86/alternatives: text

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Message-ID: <20180906183157.GK24106@hirez.programming.kicks-ass.net>
Date:   Thu, 6 Sep 2018 20:31:57 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Andy Lutomirski <luto@...capital.net>
Cc:     Nadav Amit <namit@...are.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>, X86 ML <x86@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        linux-arch <linux-arch@...r.kernel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Jiri Kosina <jkosina@...e.cz>,
        Andy Lutomirski <luto@...nel.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v2 0/6] x86/alternatives: text_poke() fixes

On Thu, Sep 06, 2018 at 11:09:23AM -0700, Andy Lutomirski wrote:
> > On Sep 6, 2018, at 10:58 AM, Nadav Amit <namit@...are.com> wrote:
> > It depends what security you want. Some may consider even the short
> > time-window in which the kernel code is writable from other cores as
> > insufficient for security.
> > 
> > In addition, the set removes the need for remote TLB shootdowns that
> > text_poke() - with this fix - requires.
> > 
> 
> I’m personally in favor of not needing a global broadcast flush to install kprobes.

That's fine. But at that point its an optimization, not a correctness
issue.