[PATCH] arm64: Correct virt_addr_valid

[Will Deacon]

On Wed, Dec 11, 2013 at 01:23:02AM +0000, Laura Abbott wrote:
> The definition of virt_addr_valid is that virt_addr_valid should
> return true if and only if virt_to_page returns a valid pointer.
> The current definition of virt_addr_valid only checks against the
> virtual address range. There's no guarantee that just because a
> virtual address falls bewteen PAGE_OFFSET and high_memory the
> associated physical memory has a valid backing struct page. Follow
> the example of other architectures and convert to pfn_valid to
> verify that the virtual address is actually valid.
> 
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Will Deacon <will.deacon at arm.com>
> Cc: Nicolas Pitre <nico at linaro.org>
> Signed-off-by: Laura Abbott <lauraa at codeaurora.org>
> ---
>  arch/arm64/include/asm/memory.h |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index 3776217..9dc5dc3 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -146,8 +146,7 @@ static inline void *phys_to_virt(phys_addr_t x)
>  #define ARCH_PFN_OFFSET		PHYS_PFN_OFFSET
>  
>  #define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
> -#define	virt_addr_valid(kaddr)	(((void *)(kaddr) >= (void *)PAGE_OFFSET) && \
> -				 ((void *)(kaddr) < (void *)high_memory))
> +#define	virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)

Hmm, this is pretty expensive on both arm and arm64, since we end up doing a
binary search through all of the memblocks.

Are you seeing real problems with the current code?

Will