linux-kernel - Re: [PATCH v7 2/2] ARM hibernation / suspend-to-disk

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Date:	Thu, 6 Mar 2014 20:42:51 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Sebastian Capella <sebastian.capella@...aro.org>
Cc:	linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	linaro-kernel@...ts.linaro.org,
	linux-arm-kernel@...ts.infradead.org,
	Len Brown <len.brown@...el.com>,
	Russell King <linux@....linux.org.uk>,
	Jonathan Austin <jonathan.austin@....com>,
	Victor Kamensky <victor.kamensky@...aro.org>,
	Nicolas Pitre <nico@...aro.org>,
	Will Deacon <will.deacon@....com>,
	Uwe Kleine-K??nig <u.kleine-koenig@...gutronix.de>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Laura Abbott <lauraa@...eaurora.org>,
	Sricharan R <r.sricharan@...com>,
	Ben Dooks <ben.dooks@...ethink.co.uk>,
	Russ Dill <Russ.Dill@...com>,
	Catalin Marinas <catalin.marinas@....com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Stefano Stabellini <stefano.stabellini@...citrix.com>,
	Jiang Liu <liuj97@...il.com>
Subject: Re: [PATCH v7 2/2] ARM hibernation / suspend-to-disk

On 03/05, Sebastian Capella wrote:
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index 8756e4b..d32adbb 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -291,6 +291,7 @@ static inline void *phys_to_virt(phys_addr_t x)
>   */
>  #define __pa(x)			__virt_to_phys((unsigned long)(x))
>  #define __va(x)			((void *)__phys_to_virt((phys_addr_t)(x)))
> +#define __pa_symbol(x)		__pa((unsigned long)(x))

Thanks for removing RELOC_HIDE, as Russell already stated it's
never been necessary on ARM.

Looking at this definition now it doesn't look right. Isn't
&__nosave_begin a virtual address? Casting it to an unsigned long
isn't going to give you a physical address. Why can't we use
__pa()?

> +extern const void __nosave_begin, __nosave_end;
> +
> +int pfn_is_nosave(unsigned long pfn)
> +{
> +	unsigned long nosave_begin_pfn =
> +			__pa_symbol(&__nosave_begin) >> PAGE_SHIFT;
> +	unsigned long nosave_end_pfn =
> +			PAGE_ALIGN(__pa_symbol(&__nosave_end)) >> PAGE_SHIFT;
> +
> +	return (pfn >= nosave_begin_pfn) && (pfn < nosave_end_pfn);
> +}

Perhaps this code could be:

	unsigned long nosave_begin_pfn = virt_to_pfn(&__nosave_begin);
	unsigned long nosave_end_pfn = virt_to_pfn(&__nosave_end);

	return (pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn);

or if virt_to_pfn() doesn't exist on ARM and we can't add it for
some reason:

	unsigned long nosave_begin_pfn = __phys_to_pfn(__pa(&__nosave_begin));
	unsigned long nosave_end_pfn = __phys_to_pfn(__pa(&__nosave_end));

	return (pfn >= nosave_begin_pfn) && (pfn <= nosave_end_pfn);

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