linux-kernel - Re: [PATCH v3] x86/vmware: use unsigned integer for shifting

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Message-ID: <YpIpL728ii08D9uK@worktop.programming.kicks-ass.net>
Date:   Sat, 28 May 2022 15:52:47 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Shreenidhi Shedi <yesshedi@...il.com>
Cc:     srivatsa@...il.mit.edu, amakhalov@...are.com, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        hpa@...or.com, virtualization@...ts.linux-foundation.org,
        pv-drivers@...are.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Shreenidhi Shedi <sshedi@...are.com>
Subject: Re: [PATCH v3] x86/vmware: use unsigned integer for shifting

On Fri, May 27, 2022 at 11:27:37PM +0530, Shreenidhi Shedi wrote:
> From: Shreenidhi Shedi <sshedi@...are.com>
> 
> Shifting signed 32-bit value by 31 bits is implementation-defined
> behaviour. Using unsigned is better option for this.

The kernel builds with -fno-strict-overflow and as such this behaviour
is well defined.

> Fixes: 4cca6ea04d31 ("x86/apic: Allow x2apic without IR on VMware platform")

Nothing broken, therefore nothing fixed.