Messages in this thread | | | Date | Fri, 23 Aug 2019 16:02:33 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v8 11/27] x86/mm: Introduce _PAGE_DIRTY_SW |
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On Tue, Aug 13, 2019 at 01:52:09PM -0700, Yu-cheng Yu wrote:
> +static inline pte_t pte_move_flags(pte_t pte, pteval_t from, pteval_t to) > +{ > + if (pte_flags(pte) & from) > + pte = pte_set_flags(pte_clear_flags(pte, from), to); > + return pte; > +}
Aside of the whole conditional thing (I agree it would be better to have this unconditionally); the function doesn't really do as advertised.
That is, if @from is clear, it doesn't endeavour to make sure @to is also clear.
Now it might be sufficient, but in that case it really needs a comment and or different name.
An implementation that actually moves the bit is something like:
pteval_t a,b;
a = native_pte_value(pte); b = (a >> from_bit) & 1; a &= ~((1ULL << from_bit) | (1ULL << to_bit)); a |= b << to_bit; return make_native_pte(a);
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