linux-kernel - Re: [PATCH] arm64: remove kaslr-seed node when it had used

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Message-ID: <20231117112936.GA28997@willie-the-truck>
Date:   Fri, 17 Nov 2023 11:29:37 +0000
From:   Will Deacon <will@...nel.org>
To:     Enlin Mu <enlin.mu@...look.com>
Cc:     catalin.marinas@....com, enlin.mu@...soc.com, enlinmu@...il.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64: remove kaslr-seed node when it had used

On Tue, Nov 14, 2023 at 09:55:51PM +0800, Enlin Mu wrote:
> From: Enlin Mu <enlin.mu@...soc.com>
> 
> If this node value is zero,it means that kaslr is enabled.
> Removing it for the system safe,nobody knows if this feature is
> enable or not.
> 
> Signed-off-by: Enlin Mu <enlin.mu@...soc.com>
> ---
>  arch/arm64/kernel/pi/kaslr_early.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/kernel/pi/kaslr_early.c b/arch/arm64/kernel/pi/kaslr_early.c
> index 17bff6e399e4..bc35d4ed84b7 100644
> --- a/arch/arm64/kernel/pi/kaslr_early.c
> +++ b/arch/arm64/kernel/pi/kaslr_early.c
> @@ -81,7 +81,7 @@ static u64 get_kaslr_seed(void *fdt)
>  		return 0;
>  
>  	ret = fdt64_to_cpu(*prop);
> -	*prop = 0;
> +	fdt_nop_property(fdt, node, "kaslr-seed");
>  	return ret;
>  }

Why is it a problem to know that KASLR is enabled? Wouldn't the presence
of the FDT_NOPs also give a pretty good hint?

Will