Date: Thu, 23 Jul 2015 21:02:58 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Jason Baron <jasonbaron0@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>, Borislav Petkov <bp@alien8.de>,
        Andy Lutomirski <luto@amacapital.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Mikulas Patocka <mpatocka@redhat.com>,
        Paul Mackerras <paulus@samba.org>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Vince Weaver <vince@deater.net>, "hillf.zj" <hillf.zj@alibaba-inc.com>,
        Valdis Kletnieks <Valdis.Kletnieks@vt.edu>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Kernel broken on processors without performance counters
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On Thu, Jul 23, 2015 at 01:33:36PM -0400, Jason Baron wrote:
> > That would be bad, how can we force it to emit 5 bytes?

> hmm....I don't think that's an issue, the patching code can
> detect if its a 2-byte jump - 0xeb, or 5-byte: 0xe9, and do
> the correct no-op. Same going the other way. See the code
> I posted a few mails back. In fact, this gets us to the
> smaller 2-byte no-ops in cases where we are initialized
> to jump.

Ah yes, I looked right over that.

I think that if we want to go do that, it should be a separate patch
though.
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