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    SubjectRe: [PATCH v3 1/3] bits: introduce fixed-type genmasks
    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@intel.com> 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().


    > > -#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.

    > > +#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



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