Re: [Xen-devel] [PATCH v2] xen/arm: Fix the issue in cmp_mmio_handler used in find_mmio_handler

[Julien Grall <julien.grall@xxxxxxx>]

Hi Bhupinder,

On 09/29/2017 01:33 AM, Bhupinder Thakur wrote:
> This function returns true/false based on whether the key value
Technically, this function returns 3 values: -1/0/1. The commit message 
should be updated to reflect that.
> is in the range (start, start+size). However, it should check against
> (start, start+size-1) because start+size falls outside the range.
>
> This resulted in returning a wrong mmio_handler for a given mmio address which
> happened to be start+size.
>
> This bug was introduced when the mmio region search was switched from
> linear search to binary search in the following commit:
>
> 8047e09 "xen/arm: io: Use binary search for mmio handler lookup".
>
> This change may have to be back-ported to 4.8 also.
FIY, this does not need to be in the commit message. You could add after 
"---". When committed, it will get removed.
> Signed-off-by: Bhupinder Thakur <bhupinder.thakur@xxxxxxxxxx>
> ---
> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> CC: Julien Grall <julien.grall@xxxxxxx>
>
>   xen/arch/arm/io.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/io.c b/xen/arch/arm/io.c
> index e216128..c748d8f 100644
> --- a/xen/arch/arm/io.c
> +++ b/xen/arch/arm/io.c
> @@ -79,7 +79,7 @@ static int cmp_mmio_handler(const void *key, const void *elem)
>       if ( handler0->addr < handler1->addr )
>           return -1;
>   
> -    if ( handler0->addr > (handler1->addr + handler1->size) )
> +    if ( handler0->addr >= (handler1->addr + handler1->size) )
>           return 1;
>   
>       return 0;
Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel