linux-kernel - Re: [PATCH V2 04/20] x86: kcore: Give entry trampolines all the same offset in kcore

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Message-ID: <47ed588e-c4d6-1e69-d9da-e4d41e448ef4@linux.intel.com>
Date:   Thu, 17 May 2018 10:54:18 -0700
From:   Dave Hansen <dave.hansen@...ux.intel.com>
To:     Adrian Hunter <adrian.hunter@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...ux.intel.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>, Jiri Olsa <jolsa@...hat.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH V2 04/20] x86: kcore: Give entry trampolines all the same
 offset in kcore

On 05/17/2018 02:21 AM, Adrian Hunter wrote:
> @@ -149,9 +149,9 @@ static void __init setup_cpu_entry_area(int cpu)
>  
>  	cea_set_pte(&get_cpu_entry_area(cpu)->entry_trampoline,
>  		     __pa_symbol(_entry_trampoline), PAGE_KERNEL_RX);
> -	kclist_add(&per_cpu(kcore_entry_trampoline, cpu),
> -		   &get_cpu_entry_area(cpu)->entry_trampoline, PAGE_SIZE,
> -		   KCORE_TEXT);
> +	kclist_add_remap(&per_cpu(kcore_entry_trampoline, cpu),
> +			 _entry_trampoline,
> +			 &get_cpu_entry_area(cpu)->entry_trampoline, PAGE_SIZE);
>  #endif
>  	percpu_setup_debug_store(cpu);
>  }

Why do you bother adding then immediately removing this code?