linux-kernel - Re: [PATCH v5 02/10] x86/jump_label: Use text_poke

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Date:   Tue, 20 Nov 2018 18:47:11 +0000
From:   Nadav Amit <namit@...are.com>
To:     "H. Peter Anvin" <hpa@...or.com>
CC:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        X86 ML <x86@...nel.org>, Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Damian Tometzki <linux_dti@...oud.com>,
        linux-integrity <linux-integrity@...r.kernel.org>,
        linux-security-module <linux-security-module@...r.kernel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCH v5 02/10] x86/jump_label: Use text_poke_early() during
 early init

> On Nov 20, 2018, at 10:23 AM, H. Peter Anvin <hpa@...or.com> wrote:
> 
> On 11/20/18 10:18 AM, Peter Zijlstra wrote:
>>> Can't we make this test in text_poke() directly, please?
>> 
>> He does that in 9/10 iirc.
> 
> No, in 9/10 he does that change locally for the jump_label, but there is
> absolutely no reason not to do that test in text_poke() proper, and
> simply use text_poke() everywhere in the kernel.

The decision in __jump_label_transform() is between text_poke_early() and
text_poke_bp() ( and not text_poke() ).

Moveover, text_poke_early() is also used when a module is loaded - a
decision which based on the “init" argument.

For these two reasons, I don’t see how the change you proposed can be
performed.