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From: Andy Lutomirski <luto@amacapital.net>
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Date: Mon, 29 Sep 2014 10:30:31 -0700
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To: Chuck Ebbert <cebbert.lkml@gmail.com>, Anish Bhatt <anish@chelsio.com>
CC: linux-kernel@vger.kernel.org, x86@kernel.org, tglx@linutronix.de,
        mingo@redhat.com, hpa@zytor.com, sebastian@fds-team.de
Subject: Re: [PATCH] x86 : Ensure X86_FLAGS_NT is cleared on syscall entry
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On 09/25/2014 04:00 PM, Chuck Ebbert wrote:
> #include <stdio.h>
> #include <unistd.h>
> 
> int main()
> {
> 	asm volatile("pushfq           \n\t" \
> 		     "pop %rax         \n\t" \
> 		     "or $0x4000,%rax  \n\t" \
> 		     "push %rax        \n\t" \
> 		     "popfq            \n\t");

You're missing clobbers here.  But fixing that has no effect.

> 	sleep(1);
> 
> 	return 0;
> }