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Date: Wed, 10 Jan 2018 09:01:02 +0100
From: Ingo Molnar <mingo@kernel.org>
To: Willy Tarreau <w@1wt.eu>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
        Andy Lutomirski <luto@kernel.org>,
        Borislav Petkov <bp@alien8.de>,
        Brian Gerst <brgerst@gmail.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Kees Cook <keescook@chromium.org>
Subject: Re: [RFC PATCH v2 3/6] x86/pti: add a per-cpu variable pti_disable
Message-ID: <20180110080102.7ggggtruidb53yfu@gmail.com>
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* Willy Tarreau <w@1wt.eu> wrote:

> [...] If we had "pit_enabled", something like this could be confusing because 
> it's not obvious whether this pti_enabled *enforces* PTI or if its absence 
> disables it :
> 
> 	cmpb $0, PER_CPU_VAR(pti_enabled)
> 	jz .Lend\@

The natural sequence would be:

	cmpb $1, PER_CPU_VAR(pti_enabled)
	jne .Lend\@

which is not confusing to me at all.

Thanks,

	Ingo