Subject: Re: [PATCH 4/5] powerpc/64: Add VIRTUAL_BUG_ON checks for __va and __pa addresses

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Wed, 24 Jul 2019 15:29:28 +0530

Nicholas Piggin <[email-masked]> writes:

> Ensure __va is given a physical address below PAGE_OFFSET, and __pa is
> given a virtual address above PAGE_OFFSET.
>

Reviewed-by: Aneesh Kumar K.V <[email-masked]>

> Signed-off-by: Nicholas Piggin <[email-masked]>
> ---
>  arch/powerpc/include/asm/page.h | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
> index 0d52f57fca04..c8bb14ff4713 100644
> --- a/arch/powerpc/include/asm/page.h
> +++ b/arch/powerpc/include/asm/page.h
> @@ -215,9 +215,19 @@ static inline bool pfn_valid(unsigned long pfn)
>  /*
>   * gcc miscompiles (unsigned long)(&static_var) - PAGE_OFFSET
>   * with -mcmodel=medium, so we use & and | instead of - and + on 64-bit.
> + * This also results in better code generation.
>   */
> -#define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) | PAGE_OFFSET))
> -#define __pa(x) ((unsigned long)(x) & 0x0fffffffffffffffUL)
> +#define __va(x)								\
> +({									\
> +	VIRTUAL_BUG_ON((unsigned long)(x) >= PAGE_OFFSET);		\
> +	(void *)(unsigned long)((phys_addr_t)(x) | PAGE_OFFSET);	\
> +})

Can we make that static inline? Is there a need for __pa and __va to be
#define like we do #ifndef anywhere?

> +
> +#define __pa(x)								\
> +({									\
> +	VIRTUAL_BUG_ON((unsigned long)(x) < PAGE_OFFSET);		\
> +	(unsigned long)(x) & 0x0fffffffffffffffUL;			\
> +})
>  
>  #else /* 32-bit, non book E */
>  #define __va(x) ((void *)(unsigned long)((phys_addr_t)(x) + PAGE_OFFSET - MEMORY_START))
> -- 
> 2.22.0