Re: [Xen-devel] [PATCH v5 08/12] arm/mem_access: Introduce GENMASK_ULL bit operation

[Julien Grall <julien.grall@xxxxxxx>]

Hi Sergej,

On 06/27/2017 12:52 PM, Sergej Proskurin wrote:
> The current implementation of GENMASK is capable of creating bitmasks of
> 32-bit values on AArch32 and 64-bit values on AArch64. As we need to
> create masks for 64-bit values on AArch32 as well, in this commit we
> introduce the GENMASK_ULL bit operation.
>
> Signed-off-by: Sergej Proskurin <proskurin@xxxxxxxxxxxxx> > ---
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> ---
>   xen/include/asm-arm/config.h | 2 ++ >   xen/include/xen/bitops.h     | 2 ++
This is common code and the relevant maintainers should have been CCed.

This is not the first time we are trying to introduce GENMASK_ULL. I 
would recommend you to read the following discussion:
https://patchwork.kernel.org/patch/9665869/

Cheers,

>   2 files changed, 4 insertions(+)
>
> diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
> index 5b6f3c985d..7fa412f1b1 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 64
> +
>   /* 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 bd0883ab22..47170c9bfd 100644
> --- a/xen/include/xen/bitops.h
> +++ b/xen/include/xen/bitops.h
> @@ -9,6 +9,8 @@
>    */
>   #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
--
Julien Grall

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