linux-kernel - Re: [x86, build] 6dafca9780: WARNING:at_arch/x86/kernel/ftrace.c:#ftrace_verify

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Message-ID: <YD4DM6uAETid7j4l@hirez.programming.kicks-ass.net>
Date:   Tue, 2 Mar 2021 10:19:47 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Sami Tolvanen <samitolvanen@...gle.com>,
        kernel test robot <oliver.sang@...el.com>,
        Kees Cook <keescook@...omium.org>,
        LKML <linux-kernel@...r.kernel.org>, lkp@...ts.01.org,
        kernel test robot <lkp@...el.com>
Subject: Re: [x86, build] 6dafca9780:
 WARNING:at_arch/x86/kernel/ftrace.c:#ftrace_verify_code

On Mon, Mar 01, 2021 at 08:15:26PM -0500, Steven Rostedt wrote:
> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
> index 7edbd5ee5ed4..e8afc765e00a 100644
> --- a/arch/x86/kernel/ftrace.c
> +++ b/arch/x86/kernel/ftrace.c
> @@ -36,6 +36,7 @@
>  #ifdef CONFIG_DYNAMIC_FTRACE
>  
>  static int ftrace_poke_late = 0;
> +static const char p6_nop[] = { P6_NOP5 };

I don't understand this approach, why not simply rewrite all the nops at
boot and not worry about it when modifying the code later?