On 17/11/2020 16.42, Janosch Frank wrote:
> Query/feature bits are commonly tested via MSB bit numbers on
> s390. Let's add test bit functions, so we don't need to copy code to
> test query bits.
>
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> ---
> lib/s390x/asm/bitops.h | 16 ++++++++++++++++
> lib/s390x/asm/facility.h | 3 ++-
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/lib/s390x/asm/bitops.h b/lib/s390x/asm/bitops.h
> index e7cdda9..a272dd7 100644
> --- a/lib/s390x/asm/bitops.h
> +++ b/lib/s390x/asm/bitops.h
> @@ -7,4 +7,20 @@
>
> #define BITS_PER_LONG 64
>
> +static inline bool test_bit(unsigned long nr,
> + const volatile unsigned long *ptr)
> +{
> + const volatile unsigned char *addr;
> +
> + addr = ((const volatile unsigned char *)ptr);
> + addr += (nr ^ (BITS_PER_LONG - 8)) >> 3;
> + return (*addr >> (nr & 7)) & 1;
> +}
> +
> +static inline bool test_bit_inv(unsigned long nr,
> + const volatile unsigned long *ptr)
> +{
> + return test_bit(nr ^ (BITS_PER_LONG - 1), ptr);
> +}
I think you should mention in the patch description that these functions
match the implementations in the kernel (and thus are good for kernel
developers who are used to these).
Thus I think you should also now add a license statement to this file
("SPDX-License-Identifier: GPL-2.0" or so).
With these modifications:
Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
