Re: [PATCH] crypto: ccree - avoid out-of-range warnings from clang

[Gilad Ben-Yossef]

Hi,

Thank you Arnd.

On Mon, Sep 27, 2021 at 3:18 PM Arnd Bergmann <arnd@xxxxxxxxxx> wrote:
>
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> clang points out inconsistencies in the FIELD_PREP() invocation in
> this driver that result from the 'mask' being a 32-bit value:
>
> drivers/crypto/ccree/cc_driver.c:117:18: error: result of comparison of constant 18446744073709551615 with expression of type 'u32' (aka 'unsigned int') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
>         cache_params |= FIELD_PREP(mask, val);
>                         ^~~~~~~~~~~~~~~~~~~~~
> include/linux/bitfield.h:94:3: note: expanded from macro 'FIELD_PREP'
>                 __BF_FIELD_CHECK(_mask, 0ULL, _val, "FIELD_PREP: ");    \
>                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> include/linux/bitfield.h:52:28: note: expanded from macro '__BF_FIELD_CHECK'
>                 BUILD_BUG_ON_MSG((_mask) > (typeof(_reg))~0ull,         \
>                 ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> This does not happen in other places that just pass a constant here.
>
> Work around the warnings by widening the type of the temporary variable.
>
> Fixes: 05c2a705917b ("crypto: ccree - rework cache parameters handling")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Acked-by: Gilad ben-Yossef <gilad@xxxxxxxxxxxxx>

Gilad



-- 
Gilad Ben-Yossef
Chief Coffee Drinker

values of β will give rise to dom!