linux-kernel - Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64

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Message-ID: <20181129115524.3fb7d994@gandalf.local.home>
Date:   Thu, 29 Nov 2018 11:55:24 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...capital.net>,
        Andrew Lutomirski <luto@...nel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, mhiramat@...nel.org,
        jbaron@...mai.com, Jiri Kosina <jkosina@...e.cz>,
        David.Laight@...lab.com, bp@...en8.de, julia@...com,
        jeyu@...nel.org, Peter Anvin <hpa@...or.com>
Subject: Re: [PATCH v2 4/4] x86/static_call: Add inline static call
 implementation for x86-64

On Thu, 29 Nov 2018 08:50:16 -0800
Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> Instead, I'd suggest:
> 
>  - just restart the instruction (with the suggested "ptregs->rip --")
> 
>  - to avoid any "oh, we're not making progress" issues, just fix the
> instruction yourself to be the right call, by looking it up in the
> "what needs to be fixed" tables.

So basically this will cause the code to go into a spin while we are
doing the update, right?

-- Steve