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

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Message-ID: <20180129192108.GR2249@hirez.programming.kicks-ass.net>
Date:   Mon, 29 Jan 2018 20:21:08 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
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 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.