linux-kernel - Re: [PATCH 03/24] x86/paravirt: Annotate indirect calls

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Message-ID: <20180130160237.nimxrlykl4ttsfuk@treble>
Date:   Tue, 30 Jan 2018 10:02:37 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     David Woodhouse <dwmw2@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, Dave Hansen <dave.hansen@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Arjan Van De Ven <arjan.van.de.ven@...el.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jun Nakajima <jun.nakajima@...el.com>,
        Asit Mallick <asit.k.mallick@...el.com>,
        Jason Baron <jbaron@...mai.com>
Subject: Re: [PATCH 03/24] x86/paravirt: Annotate indirect calls

On Mon, Jan 29, 2018 at 08:21:08PM +0100, Peter Zijlstra wrote:
> On Mon, Jan 29, 2018 at 12:38:50PM -0600, Josh Poimboeuf wrote:
> > On Tue, Jan 23, 2018 at 04:25:42PM +0100, Peter Zijlstra wrote:
> > > Paravirt emits indirect calls which get flagged by objtool retpoline
> > > checks, annotate it away because all these indirect calls will be
> > > patched out before we start userspace.
> > 
> > There's one condition where this isn't true: the 'noreplace-paravirt'
> > cmdline option.  I have no idea why that option exists but we should
> > consider just removing it.
> 
> Smells like a debug remnant from back when all this patching crap was
> new. And yes, that sounds like something that should maybe go away. Esp.
> for retpoline builds.

Ok, I'll whip up a patch to remove it and see if anybody complains.

-- 
Josh