On 7/8/20 6:04 PM, Nick Desaulniers wrote:
> This macro has a few expansion sites that pass literal 0s as parameters.
> Split these up so that we do the precise checks where we care about
> them.
>
> Suggested-by: Alex Elder <el...@linaro.org>
> Signed-off-by: Nick Desaulniers <ndesaulni...@google.com>
I do like this better. It makes it more obvious when only
the mask is being verified (in FIELD_FIT() for example).
I also appreciate that you distinguished the register
checks from the value checks.
- field masks must be (2^x - 1) << y, x > 0, and constant
- values must be representable within a field mask
- registers must be able to represent the field mask
Reviewed-by: Alex Elder <el...@linaro.org>
> ---
> Changes V1-V2:
> * New patch in v2.
> * Rebased on 0001.
>
> .../netronome/nfp/nfpcore/nfp_nsp_eth.c | 11 ++++----
> include/linux/bitfield.h | 26 +++++++++++++------
> 2 files changed, 24 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c
> b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c
> index 311a5be25acb..938fc733fccb 100644
> --- a/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c
> +++ b/drivers/net/ethernet/netronome/nfp/nfpcore/nfp_nsp_eth.c
> @@ -492,11 +492,12 @@ nfp_eth_set_bit_config(struct nfp_nsp *nsp, unsigned
> int raw_idx,
> return 0;
> }
>
> -#define NFP_ETH_SET_BIT_CONFIG(nsp, raw_idx, mask, val, ctrl_bit) \
> - ({ \
> - __BF_FIELD_CHECK(mask, 0ULL, val, "NFP_ETH_SET_BIT_CONFIG: "); \
> - nfp_eth_set_bit_config(nsp, raw_idx, mask, __bf_shf(mask), \
> - val, ctrl_bit); \
> +#define NFP_ETH_SET_BIT_CONFIG(nsp, raw_idx, mask, val, ctrl_bit)
> \
> + ({
> \
> + __BF_FIELD_CHECK_MASK(mask, "NFP_ETH_SET_BIT_CONFIG: ");
> \
> + __BF_FIELD_CHECK_VAL(mask, val, "NFP_ETH_SET_BIT_CONFIG: ");
> \
> + nfp_eth_set_bit_config(nsp, raw_idx, mask, __bf_shf(mask),
> \
> + val, ctrl_bit);
> \
> })
>
> /**
> diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
> index 4e035aca6f7e..79651867beb3 100644
> --- a/include/linux/bitfield.h
> +++ b/include/linux/bitfield.h
> @@ -41,18 +41,26 @@
>
> #define __bf_shf(x) (__builtin_ffsll(x) - 1)
>
> -#define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \
> +#define __BF_FIELD_CHECK_MASK(_mask, _pfx) \
> ({ \
> BUILD_BUG_ON_MSG(!__builtin_constant_p(_mask), \
> _pfx "mask is not constant"); \
> BUILD_BUG_ON_MSG((_mask) == 0, _pfx "mask is zero"); \
> + __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \
> + (1ULL << __bf_shf(_mask))); \
> + })
> +
> +#define __BF_FIELD_CHECK_VAL(_mask, _val, _pfx)
> \
> + ({ \
> BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \
> ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \
> _pfx "value too large for the field"); \
> - BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull, \
> + })
> +
> +#define __BF_FIELD_CHECK_REG(_mask, _reg, _pfx)
> \
> + ({ \
> + BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ULL, \
> _pfx "type of reg too small for mask"); \
> - __BUILD_BUG_ON_NOT_POWER_OF_2((_mask) + \
> - (1ULL << __bf_shf(_mask))); \
> })
>
> /**
> @@ -64,7 +72,7 @@
> */
> #define FIELD_MAX(_mask) \
> ({ \
> - __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_MAX: "); \
> + __BF_FIELD_CHECK_MASK(_mask, "FIELD_MAX: "); \
> (typeof(_mask))((_mask) >> __bf_shf(_mask)); \
> })
>
> @@ -77,7 +85,7 @@
> */
> #define FIELD_FIT(_mask, _val)
> \
> ({ \
> - __BF_FIELD_CHECK(_mask, 0ULL, 0ULL, "FIELD_FIT: "); \
> + __BF_FIELD_CHECK_MASK(_mask, "FIELD_FIT: "); \
> !((((typeof(_mask))_val) << __bf_shf(_mask)) & ~(_mask)); \
> })
>
> @@ -91,7 +99,8 @@
> */
> #define FIELD_PREP(_mask, _val)
> \
> ({ \
> - __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: "); \
> + __BF_FIELD_CHECK_MASK(_mask, "FIELD_PREP: "); \
> + __BF_FIELD_CHECK_VAL(_mask, _val, "FIELD_PREP: "); \
> ((typeof(_mask))(_val) << __bf_shf(_mask)) & (_mask); \
> })
>
> @@ -105,7 +114,8 @@
> */
> #define FIELD_GET(_mask, _reg)
> \
> ({ \
> - __BF_FIELD_CHECK(_mask, _reg, 0U, "FIELD_GET: "); \
> + __BF_FIELD_CHECK_MASK(_mask, "FIELD_GET: "); \
> + __BF_FIELD_CHECK_REG(_mask, _reg, "FIELD_GET: "); \
> (typeof(_mask))(((_reg) & (_mask)) >> __bf_shf(_mask)); \
> })
>
>
