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Date: Thu, 1 Feb 2018 16:11:36 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Josh Poimboeuf <jpoimboe@redhat.com>, 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>
Subject: Re: [PATCH 4/7] x86,nospec: Annotate indirect calls/jumps
Message-ID: <20180201151136.GX2249@hirez.programming.kicks-ass.net>
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On Thu, Feb 01, 2018 at 02:55:26PM +0000, David Woodhouse wrote:
> 
> 
> On Thu, 2018-02-01 at 15:34 +0100, Peter Zijlstra wrote:
> > 
> >   * These are the bare retpoline primitives for indirect jmp and call.
> >   * Do not use these directly; they only exist to make the ALTERNATIVE
> >   * invocation below less ugly.
> > @@ -102,9 +114,9 @@
> >  .macro JMP_NOSPEC reg:req
> >  #ifdef CONFIG_RETPOLINE
> >         ANNOTATE_NOSPEC_ALTERNATIVE
> > -       ALTERNATIVE_2 __stringify(jmp *\reg),                           \
> > +       ALTERNATIVE_2 __stringify(ANNOTATE_RETPOLINE_SAFE; jmp *\reg),  \
> >                 __stringify(RETPOLINE_JMP \reg), X86_FEATURE_RETPOLINE, \
> > -               __stringify(lfence; jmp *\reg), X86_FEATURE_RETPOLINE_AMD
> > +               __stringify(lfence; ANNOTATE_RETPOLINE_SAFE; jmp *\reg), X86_FEATURE_RETPOLINE_AMD
> >  #else
> >         jmp     *\reg
> >  #endif
> 
> The first one, yes. But the second one for the AMD retpoline is
> redundant, isn't it? Objtool isn't going to look there.

It was when I wrote it.. lemme try again.