Re: [Xen-devel] [PATCH v5 01/30] bitops: add GENMASK_ULL

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 6 Apr 2017, Andre Przywara wrote:
> To safely handle 64-bit registers even on 32-bit systems, introduce
> a GENMASK_ULL variant (lifted from Linux).
> This adds a BITS_PER_LONG_LONG define as well.
> Also fix a bug in the comment for the existing GENMASK variant.
> 
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

> ---
>  xen/include/asm-arm/config.h | 2 ++
>  xen/include/xen/bitops.h     | 5 ++++-
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
> index b2edf95..1f730ce 100644
> --- a/xen/include/asm-arm/config.h
> +++ b/xen/include/asm-arm/config.h
> @@ -19,6 +19,8 @@
>  #define BITS_PER_LONG (BYTES_PER_LONG << 3)
>  #define POINTER_ALIGN BYTES_PER_LONG
>  
> +#define BITS_PER_LONG_LONG (sizeof (long long) * BITS_PER_BYTE)
> +
>  /* xen_ulong_t is always 64 bits */
>  #define BITS_PER_XEN_ULONG 64
>  
> diff --git a/xen/include/xen/bitops.h b/xen/include/xen/bitops.h
> index bd0883a..9261e06 100644
> --- a/xen/include/xen/bitops.h
> +++ b/xen/include/xen/bitops.h
> @@ -5,11 +5,14 @@
>  /*
>   * Create a contiguous bitmask starting at bit position @l and ending at
>   * position @h. For example
> - * GENMASK(30, 21) gives us the 32bit vector 0x01fe00000.
> + * GENMASK(30, 21) gives us the 32bit vector 0x7fe00000.
>   */
>  #define GENMASK(h, l) \
>      (((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
>  
> +#define GENMASK_ULL(h, l) \
> +    (((~0ULL) << (l)) & (~0ULL >> (BITS_PER_LONG_LONG - 1 - (h))))
> +
>  /*
>   * ffs: find first bit set. This is defined the same way as
>   * the libc and compiler builtin ffs routines, therefore
> -- 
> 2.8.2
> 

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