[RFC PATCH v4 10/11] lib: vdso: Allow arches to override the ns shift operation
tglx at linutronix.de
Thu Jan 16 11:57:03 PST 2020
Andy Lutomirski <luto at 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:
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.
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