Re: Re: [PATCH v3 1/3] bits: introduce fixed-type genmasks

[Lucas De Marchi]

On Wed, Feb 21, 2024 at 11:04:22PM +0200, Andy Shevchenko wrote:
> On Wed, Feb 21, 2024 at 10:30:02PM +0200, Dmitry Baryshkov wrote:
> > On Thu, 8 Feb 2024 at 09:45, Lucas De Marchi <lucas.demarchi@xxxxxxxxx> wrote:
>
> ...
>
> > > +#define BITS_PER_TYPE(type)    (sizeof(type) * BITS_PER_BYTE)
>
> Can sizeof() be used in assembly?
>
> ...
>
> > > -#define __GENMASK(h, l) \
> > > -       (((~UL(0)) - (UL(1) << (l)) + 1) & \
> > > -        (~UL(0) >> (BITS_PER_LONG - 1 - (h))))
> > > -#define GENMASK(h, l) \
> > > -       (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
>
> > > +#define __GENMASK(t, h, l) \
> > > +       (GENMASK_INPUT_CHECK(h, l) + \
> > > +        (((t)~0ULL - ((t)(1) << (l)) + 1) & \
> > > +        ((t)~0ULL >> (BITS_PER_TYPE(t) - 1 - (h)))))
>
> Nevertheless, the use ~0ULL is not proper assembly, this broke initial
> implementation using UL() / ULL().

indeed.

> > > -#define __GENMASK_ULL(h, l) \
> > > -       (((~ULL(0)) - (ULL(1) << (l)) + 1) & \
> > > -        (~ULL(0) >> (BITS_PER_LONG_LONG - 1 - (h))))
> > > -#define GENMASK_ULL(h, l) \
> > > -       (GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l))
>
> Ditto.

problem here seems actually because of the cast to the final type. My
previous impl was avoiding that, but was too verbose compared to this.

I will look at reverting this.

Lucas De Marchi

> > > +#define GENMASK(h, l)          __GENMASK(unsigned long,  h, l)
> > > +#define GENMASK_ULL(h, l)      __GENMASK(unsigned long long, h, l)
> > > +#define GENMASK_U8(h, l)       __GENMASK(u8,  h, l)
> > > +#define GENMASK_U16(h, l)      __GENMASK(u16, h, l)
> > > +#define GENMASK_U32(h, l)      __GENMASK(u32, h, l)
> > > +#define GENMASK_U64(h, l)      __GENMASK(u64, h, l)
> >
> > This breaks drm-tip on arm64 architecture:
> >
> > arch/arm64/kernel/entry-fpsimd.S: Assembler messages:
> > 465arch/arm64/kernel/entry-fpsimd.S:271: Error: found 'l', expected: ')'
> > 466arch/arm64/kernel/entry-fpsimd.S:66: Info: macro invoked from here
> > 467arch/arm64/kernel/entry-fpsimd.S:271: Error: found 'l', expected: ')'
> > 468arch/arm64/kernel/entry-fpsimd.S:66: Info: macro invoked from here
> > 469arch/arm64/kernel/entry-fpsimd.S:271: Error: found 'l', expected: ')'
> > 470arch/arm64/kernel/entry-fpsimd.S:66: Info: macro invoked from here
> > 471arch/arm64/kernel/entry-fpsimd.S:271: Error: found 'l', expected: ')'
> > 472arch/arm64/kernel/entry-fpsimd.S:66: Info: macro invoked from here
> > 473arch/arm64/kernel/entry-fpsimd.S:271: Error: unexpected characters
> > following instruction at operand 3 -- `bic x2,x1,(0+(((unsigned
> > long)~0ULL-((unsigned long)(1)<<(0))+1)&((unsigned
> > long)~0ULL>>((sizeof(unsigned long)*8)-1-(3)))))'
> > 474arch/arm64/kernel/entry-fpsimd.S:66: Info: macro invoked from here
> > 475arch/arm64/kernel/entry-fpsimd.S:282: Error: found 'l', expected: ')'
> > 476arch/arm64/kernel/entry-fpsimd.S:98: Info: macro invoked from here
> > 477arch/arm64/kernel/entry-fpsimd.S:282: Error: found 'l', expected: ')'
> > 478arch/arm64/kernel/entry-fpsimd.S:98: Info: macro invoked from here
> > 479arch/arm64/kernel/entry-fpsimd.S:282: Error: found 'l', expected: ')'
> > 480arch/arm64/kernel/entry-fpsimd.S:98: Info: macro invoked from here
> > 481arch/arm64/kernel/entry-fpsimd.S:282: Error: found 'l', expected: ')'
> > 482arch/arm64/kernel/entry-fpsimd.S:98: Info: macro invoked from here
> > 483arch/arm64/kernel/entry-fpsimd.S:282: Error: unexpected characters
> > following instruction at operand 3 -- `bic x2,x1,(0+(((unsigned
> > long)~0ULL-((unsigned long)(1)<<(0))+1)&((unsigned
> > long)~0ULL>>((sizeof(unsigned long)*8)-1-(3)))))'
> > 484arch/arm64/kernel/entry-fpsimd.S:98: Info: macro invoked from here
>
> --
> With Best Regards,
> Andy Shevchenko