Messages in this thread | | | From | Andy Lutomirski <> | Date | Thu, 16 Jan 2020 12:20:59 -0800 | Subject | Re: [RFC PATCH v4 10/11] lib: vdso: Allow arches to override the ns shift operation |
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On Thu, Jan 16, 2020 at 11:57 AM Thomas Gleixner <tglx@linutronix.de> wrote: > > Andy Lutomirski <luto@kernel.org> writes: > > On Thu, Jan 16, 2020 at 9:58 AM Christophe Leroy > > > > Would mul_u64_u64_shr() be a good alternative? Could we adjust it to > > assume the shift is less than 32? That function exists to benefit > > 32-bit arches. > > We'd want mul_u64_u32_shr() for this. The rules for mult and shift are: >
That's what I meant to type...
> 1 <= mult <= U32_MAX > > 1 <= shift <= 32 > > If we want to enforce a shift < 32 we need to limit that conditionally > in the calculation/registration function. > > Thanks, > > tglx >
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