linux-kernel - Re: [PATCH] MIPS: generic: Fix KASLR for generic kernel.

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Date:   Mon, 17 Oct 2016 11:22:31 +0100
From:   James Hogan <james.hogan@...tec.com>
To:     Matt Redfearn <matt.redfearn@...tec.com>
CC:     Ralf Baechle <ralf@...ux-mips.org>, <linux-mips@...ux-mips.org>,
        <linux-kernel@...r.kernel.org>,
        Paul Burton <paul.burton@...tec.com>
Subject: Re: [PATCH] MIPS: generic: Fix KASLR for generic kernel.

Hi Matt,

On Mon, Oct 17, 2016 at 11:05:09AM +0100, Matt Redfearn wrote:
> The KASLR code requires that the plat_get_fdt() function return the
> address of the device tree, and it must be available early in the boot,
> before prom_init() is called. Move the code determining the address of
> the device tree into plat_get_fdt, and call that from prom_init().
> 
> The fdt pointer will be set up by plat_get_fdt() called from
> relocate_kernel initially and once the relocated kernel has started,
> prom_init() will use it again to determine the address in the relocated
> image.
> 
> Fixes: eed0eabd12ef

I believe this is the preferred form:

Fixes: eed0eabd12ef ("MIPS: generic: Introduce generic DT-based board support")

Otherwise looks good to me

Reviewed-by: James Hogan <james.hogan@...tec.com>

Cheers
James

> Signed-off-by: Matt Redfearn <matt.redfearn@...tec.com>
> ---
> 
>  arch/mips/generic/init.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/mips/generic/init.c b/arch/mips/generic/init.c
> index 0ea73e845440..d493ccbf274a 100644
> --- a/arch/mips/generic/init.c
> +++ b/arch/mips/generic/init.c
> @@ -30,9 +30,19 @@ static __initdata const void *mach_match_data;
>  
>  void __init prom_init(void)
>  {
> +	plat_get_fdt();
> +	BUG_ON(!fdt);
> +}
> +
> +void __init *plat_get_fdt(void)
> +{
>  	const struct mips_machine *check_mach;
>  	const struct of_device_id *match;
>  
> +	if (fdt)
> +		/* Already set up */
> +		return (void *)fdt;
> +
>  	if ((fw_arg0 == -2) && !fdt_check_header((void *)fw_arg1)) {
>  		/*
>  		 * We booted using the UHI boot protocol, so we have been
> @@ -75,12 +85,6 @@ void __init prom_init(void)
>  		/* Retrieve the machine's FDT */
>  		fdt = mach->fdt;
>  	}
> -
> -	BUG_ON(!fdt);
> -}
> -
> -void __init *plat_get_fdt(void)
> -{
>  	return (void *)fdt;
>  }
>  
> -- 
> 2.7.4
> 
> 

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