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Date: Fri, 11 Apr 2014 15:18:24 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Andy Lutomirski <luto@amacapital.net>,
	"H. Peter Anvin" <hpa@linux.intel.com>
CC: Brian Gerst <brgerst@gmail.com>, Ingo Molnar <mingo@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>, stable@vger.kernel.org
Subject: Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit
 kernels
References: <tip-kicdm89kzw9lldryb1br9od0@git.kernel.org> <CAMzpN2jx4H4p8fQr-WHxVyCHhWi0iO3WZZKyxYD7Dfa7pWkEgg@mail.gmail.com> <53483487.6030103@zytor.com> <53485BB8.1000106@mit.edu> <53485D95.9030301@zytor.com> <5348643F.1020405@mit.edu> <534865DF.2090703@linux.intel.com> <CALCETrX4BLLL1Con7+Fr5cfodHQs40qA4TE39yop2NeARdwA+A@mail.gmail.com>
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On 04/11/2014 03:15 PM, Andy Lutomirski wrote:
> 
> I just looked up my hideous code.  I was doing this to test the
> now-deleted int 0xcc vsyscall stuff.  I used modify_ldt because either
> I didn't realize that __USER32_CS was usable or I didn't think it was
> ABI.  Or I was just being silly.
> 
> But yes, breaking my hack would not matter. :)
> 

Either way, it wouldn't break it.

	-hpa