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Date: Wed, 31 Jan 2018 11:01:19 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: David Woodhouse <dwmw2@infradead.org>,
	Thomas Gleixner <tglx@linutronix.de>, linux-kernel@vger.kernel.org,
	Dave Hansen <dave.hansen@intel.com>,
	Ashok Raj <ashok.raj@intel.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Greg KH <gregkh@linuxfoundation.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	Andi Kleen <ak@linux.intel.com>,
	Arjan Van De Ven <arjan.van.de.ven@intel.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Jun Nakajima <jun.nakajima@intel.com>,
	Asit Mallick <asit.k.mallick@intel.com>,
	Jason Baron <jbaron@akamai.com>
Subject: Re: [PATCH 20/24] objtool: Another static block fail
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On Tue, Jan 30, 2018 at 09:12:21PM -0600, Josh Poimboeuf wrote:
> 
> Or, maybe we should just forget the whole thing and just stick with the
> dynamic IBRS checks with lfence.  Yes, it's less ideal for the kernel,
> but adding these acrobatics to objtool also has a cost.

For now, IBRS seems off the table entirely. But no, I really don't want
to have to unconditionally eat the LFENCE cost in all those sites.