linux-kernel - Re: [PATCH] x86/mm: Simplify redundant overlap calculation

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Date: Tue, 23 Jan 2024 08:47:08 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Dave Hansen <dave.hansen@...ux.intel.com>, linux-kernel@...r.kernel.org
Cc: David Binderman <dcb314@...mail.com>, Andy Lutomirski <luto@...nel.org>,
 Peter Zijlstra <peterz@...radead.org>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 x86@...nel.org
Subject: Re: [PATCH] x86/mm: Simplify redundant overlap calculation

On 1/23/24 08:36, Dave Hansen wrote:
> There have been a couple of reports that the two sides of the
> overlaps() calculation are redundant.  I spent way too much time
> looking at this, but I became convinced that they are redundant
> when a little test program of mine produced identical disassembly
> for both versions of the check.
> 
> Remove the second condition.  It is exactly the same as the first.
> 
> Fixes: 91ee8f5c1f50 ("x86/mm/cpa: Allow range check for static protections")
> Reported-by: David Binderman <dcb314@...mail.com>

Gah, that one escaped a moment too soon:

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>

.. obviously