linux-kernel - Re: [PATCH] of: Fix memory block alignment in early_init_dt_add_memory

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Message-Id: <20140827103048.80BBBC409CB@trevor.secretlab.ca>
Date:	Wed, 27 Aug 2014 11:30:48 +0100
From:	Grant Likely <grant.likely@...aro.org>
To:	Geert Uytterhoeven <geert+renesas@...der.be>,
	Rob Herring <robh+dt@...nel.org>
Cc:	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Geert Uytterhoeven <geert+renesas@...der.be>
Subject: Re: [PATCH] of: Fix memory block alignment in
 early_init_dt_add_memory_arch()

On Wed, 20 Aug 2014 17:10:31 +0200, Geert Uytterhoeven <geert+renesas@...der.be> wrote:
> If a memory block is not aligned to PAGE_SIZE, its base address must be
> rounded up, not down, and its size must be reduced.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>

Looks reasonable. What is the situation that exposed this problem?
Should size be checked for page alignment also?

g.

> ---
>  drivers/of/fdt.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index f46a24ffa3fe..95fa81b8ca19 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -928,7 +928,11 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
>  void __init __weak early_init_dt_add_memory_arch(u64 base, u64 size)
>  {
>  	const u64 phys_offset = __pa(PAGE_OFFSET);
> -	base &= PAGE_MASK;
> +
> +	if (!PAGE_ALIGNED(base)) {
> +		size -= PAGE_SIZE - (base & ~PAGE_MASK);
> +		base = PAGE_ALIGN(base);
> +	}
>  	size &= PAGE_MASK;
>  
>  	if (base > MAX_PHYS_ADDR) {
> -- 
> 1.9.1
> 

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