On Wed, Mar 05, 2025 at 10:00:15PM +0900, Vincent Mailhol via B4 Relay wrote: > From: Yury Norov <yury.norov@xxxxxxxxx> > > Add __GENMASK_t() which generalizes __GENMASK() to support different Is it with double underscore? I do not see it. _t is used for typedef simple types. It's unfortunate to have it in such a macro. Perhaps T or TYPE will suffice. Or perhaps we want __GENMASK_Uxx() here? > types, and implement fixed-types versions of GENMASK() based on it. > The fixed-type version allows more strict checks to the min/max values > accepted, which is useful for defining registers like implemented by > i915 and xe drivers with their REG_GENMASK*() macros. > > The strict checks rely on shift-count-overflow compiler check to fail > the build if a number outside of the range allowed is passed. > Example: > > #define FOO_MASK GENMASK_U32(33, 4) > > will generate a warning like: > > ../include/linux/bits.h:41:31: error: left shift count >= width of type [-Werror=shift-count-overflow] > 41 | (((t)~0ULL - ((t)(1) << (l)) + 1) & \ > | ^~ ... > + * __GENMASK_U*() depends on BITS_PER_TYPE() which would not work in the asm Where are the double underscore variants? I see it only for U128. > + * code as BITS_PER_TYPE() relies on sizeof(), something not available in > + * asm. Nethertheless, the concept of fixed width integers is a C thing which > + * does not apply to assembly code. -- With Best Regards, Andy Shevchenko
