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SubjectRe: [PATCH v2 2/9] mm: move __phys_to_pfn and __pfn_to_phys to asm/generic/memory_model.h
On Tue, 25 Aug 2015, Dan Williams wrote:

> From: Christoph Hellwig <hch@lst.de>
>
> Three architectures already define these, and we'll need them genericly
> soon.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> ---
> arch/arm/include/asm/memory.h | 6 ------
> arch/arm64/include/asm/memory.h | 6 ------
> arch/unicore32/include/asm/memory.h | 6 ------
> include/asm-generic/memory_model.h | 6 ++++++
> 4 files changed, 6 insertions(+), 18 deletions(-)
>
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index b7f6fb462ea0..98d58bb04ac5 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -119,12 +119,6 @@
> #endif
>
> /*
> - * Convert a physical address to a Page Frame Number and back
> - */
> -#define __phys_to_pfn(paddr) ((unsigned long)((paddr) >> PAGE_SHIFT))
> -#define __pfn_to_phys(pfn) ((phys_addr_t)(pfn) << PAGE_SHIFT)
> -
> -/*
> * Convert a page to/from a physical address
> */
> #define page_to_phys(page) (__pfn_to_phys(page_to_pfn(page)))

[...]

> diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
> index 14909b0b9cae..f20f407ce45d 100644
> --- a/include/asm-generic/memory_model.h
> +++ b/include/asm-generic/memory_model.h
> @@ -69,6 +69,12 @@
> })
> #endif /* CONFIG_FLATMEM/DISCONTIGMEM/SPARSEMEM */
>
> +/*
> + * Convert a physical address to a Page Frame Number and back
> + */
> +#define __phys_to_pfn(paddr) ((unsigned long)((paddr) >> PAGE_SHIFT))
> +#define __pfn_to_phys(pfn) ((pfn) << PAGE_SHIFT)
> +

This patch, currently in mainline as commit 012dcef3f0, breaks LPAE on
ARM32 with more than 4GB of RAM. The phys_addr_t cast in the original
ARM definition is important when LPAE is enabled as phys_addr_t is 64
bits while longs are 32 bits.


Nicolas


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