From: Paolo Bonzini <pbonzini@redhat.com>
To: Valdis.Kletnieks@vt.edu, Aurelien Jarno <aurelien@aurel32.net>
Cc: Gleb Natapov <gleb@kernel.org>,
x86@kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Aruna Hewapathirane <aruna.hewapathirane@gmail.com>
Subject: Re: Silence compiler warning in arch/x86/kvm/emulate.c
Date: Fri, 19 Feb 2016 18:56:05 +0100 [thread overview]
Message-ID: <56C75735.3010602@redhat.com> (raw)
In-Reply-To: <10537.1455904440@turing-police.cc.vt.edu>
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On 19/02/2016 18:54, Valdis.Kletnieks@vt.edu wrote:
> la can get changed here - but there's 2 cases to consider. If it's
> in a 32-bit kernel, anding with -1 is a no-op.
>
> Now if we're on a 64-bit kernel, the 'and' clears the high 32
> bits.
>
> But under what conditions is 'la' a 64-bit quantity that has any
> bits set in the high 32 bits (meaning it's a pointer to something
> over the 4G line) - but it's still valid to smash those bits?
That can happen for example if there is a non-zero segment base. Then
the linear address wraps at 4G.
Paolo
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next prev parent reply other threads:[~2016-02-19 17:56 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-29 21:49 Silence compiler warning in arch/x86/kvm/emulate.c Valdis Kletnieks
2016-02-19 11:11 ` Aurelien Jarno
2016-02-19 12:05 ` Paolo Bonzini
2016-02-19 17:04 ` Aurelien Jarno
2016-02-19 16:45 ` Aurelien Jarno
2016-02-19 17:54 ` Valdis.Kletnieks
2016-02-19 17:56 ` Paolo Bonzini [this message]
2016-02-20 0:33 ` Valdis.Kletnieks
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