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

[Christophe Leroy]

Hi Nic,

Le 24/07/2019 à 10:46, Nicholas Piggin a écrit :
> Ensure __va is given a physical address below PAGE_OFFSET, and __pa is
> given a virtual address above PAGE_OFFSET.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
>   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);	\
> +})
> +
> +#define __pa(x)								\
> +({									\
> +	VIRTUAL_BUG_ON((unsigned long)(x) < PAGE_OFFSET);		\

With this, it is likely that virt_addr_valid() BUGs on a non valid address.

I think the purpose of virt_addr_valid() is to check addresses 
seamlessly, see check_heap_object()


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