linux-kernel - Re: [PATCH 2/2] x86/mm/64: Add vsyscall page to /proc/kcore conditionally

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Date:   Mon, 5 Feb 2018 10:26:44 +0100
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jia Zhang <zhang.jia@...ux.alibaba.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] x86/mm/64: Add vsyscall page to /proc/kcore
 conditionally

On Tue, Jan 30, 2018 at 02:42:59PM +0800, Jia Zhang wrote:
> The vsyscall page should be visible only if
> vsyscall=emulate/native when dumping /proc/kcore.
> 
> Signed-off-by: Jia Zhang <zhang.jia@...ux.alibaba.com>
> ---
>  arch/x86/mm/init_64.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
> index dab78f6..3d4cf33 100644
> --- a/arch/x86/mm/init_64.c
> +++ b/arch/x86/mm/init_64.c
> @@ -1186,8 +1186,9 @@ void __init mem_init(void)
>  	register_page_bootmem_info();
>  
>  	/* Register memory areas for /proc/kcore */
> -	kclist_add(&kcore_vsyscall, (void *)VSYSCALL_ADDR,
> -		   PAGE_SIZE, KCORE_USER);
> +	if (get_gate_vma(&init_mm))
> +		kclist_add(&kcore_vsyscall, (void *)VSYSCALL_ADDR,
> +			   PAGE_SIZE, KCORE_USER);

nit, we use { } when there's more than 1 line code 

anyway the approach looks ok to me

Reviewed-by: Jiri Olsa <jolsa@...nel.org>

thanks,
jirka