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xen-devel
Re: [Xen-devel] [PATCH 2/2] x86: add pte_set_flags/clear_flags for ptefl
>>> Jeremy Fitzhardinge <jeremy@xxxxxxxx> 22.01.09 23:24 >>>
>+static inline pte_t pte_set_flags(pte_t pte, pteval_t set)
>+{
>+ pteval_t v = native_pte_val(pte);
>+
>+ return native_make_pte(v | set);
>+}
>+
>+static inline pte_t pte_clear_flags(pte_t pte, pteval_t clear)
>+{
>+ pteval_t v = native_pte_val(pte);
>+
>+ return native_make_pte(v & ~clear);
>+}
I think a comment (or event a BUG_ON()) should be added here to make
clear that this absolutely must not be used to toggle the present bit. I
even view toggling _PAGE_PSE as dangerous this way.
And alternative would be to make these macros and #undef them (or keep
them inline functions but add destructive #define-s) after all their users.
Jan
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